Living Without a Pulse

SteamyMobile writes "Can you live without a pulse? Yes, now you can. The reason why we have a pulse is because it's hard for evolution to result in turbines or continuously spinning things. The next generation of artificial hearts may have no pulse. They also have no bearings, so they should last much longer than previous attempts. In fact, engineers don't give a predicted lifespan on these models. How would your life be different without a pulse?"

Comments

Hmm

[grub]

How would your life be different without a pulse?

I would have had much more in common with my ex-wife.

Re:Hmm

[Ignignot]

How would your life be different without a pulse?

I would have had much more in common with my ex-wife.

We know you did it OJ! Just because you weren't convicted in court doesn't mean you weren't convicted in our minds!

He's Dead, Jim.

[mfh]

FTA: "The pump also has a curious side effect: people implanted with the device have no pulse."

They had better put an obvious port on it so paramedics know it's there before sending voltage through.

I can see the first really drunk guy with one of these taking a nap on the beach:

"ZZzzzzzzZZZZzzzzzZZ"

"Sir!"

"Oh my GOD! He's Dead, Jim!!!"

"He's got no pulse! Call an ambulance!"

(ambulance arrives, 10min later)

"This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal!"

"CLEAR!!!!!!!!!!!" "ZZZZAPP!!!!" /dies

Re:He's Dead, Jim.

[akadruid]

This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal
If they are so drunk they don't react in any noticable way to 10 minutes of CPR then they need the ambulance (probably just to cart of the body.)

Re:He's Dead, Jim.

[akiaki007]

(ambulance arrives, 10min later)

"This man has no pulse! I've been giving him CPR since I called you guys and I can't get a signal!"

While ths scenario is pretty funny...most CPR certified professionals check for breathing, not a pulse. And if they didn't, then they shouldn't be certified. Yes, they also check for a pulse, but not before they check for breathing. Depending on the body fat on a person, the pulse isn't always easily detected.

Re:He's Dead, Jim.

[sql*kitten]

most CPR certified professionals check for breathing, not a pulse.

Yup, ABC, Airway, Breathing, Circulation. One of the fist things they teach in First Aid class. You can have a hearbeat while not breathing, but you can't breathe without a heartbeat.

Re:He's Dead, Jim.

[finkployd]

You are correct, what everyone is being trained to check for now (at least with the Red Cross CPR training I just took) is "signs of life", not a pulse. This includes breathing, possibly pulse, etc. This is probably due to the difficulty in checking for a pulse in obese people and those with a faint pulse.

Finkployd

Re:He's Dead, Jim.

[tomknight]

Have yourself tatooed.

Reminds me of an article I read about an old lady who doesn't want to be revived if her heart stop (she seems to think that that's probabaly a good time to call it quits). The problem is no-one's going to check your wallet for a consent card for CPR, so she's had her chest tatooed with a warning saying something like "Get thos f*cking this away from my f*cking chest. If you revive me I'll sue your arse off!". No, what wasn't quite it.... but I wonder if she could sue someone for saving her life in that way (against her wishes? Would she be able to get some sort of support for the next time she falls ill and has to pay a shite load of dosh for pain releif (or whatever)?

Tom.

Re:He's Dead, Jim.

[SlamMan]

When you're unconscious, you still breathe.

Re:He's Dead, Jim.

[Atzanteol]

Actually, I just took the CPR course recently, and they specifically left out 'taking the persons pulse' and told us to rely on watching for signs of movement in the chest, and looking for breathing.

Apparently many people are very poor at checking for a pulse, and it was unreliable.

Re:He's Dead, Jim.

[SEWilco]

"CLEAR!!!!!!!!!!!" "ZZZZAPP!!!!" /dies

Why would he die?
Running electricity through where his heart used to be would not affect the insulated pump.

However, there should be a label: "Normal blood pressure 90 psi. Check oil every two years. Turn off this switch before autopsy or burial. Press red button before vigorous exercise."

Re:He's Dead, Jim.

[The Tyro]

They expand on the acronym in a couple of scenarios.

ATLS (Advanced Trauma Life Support, a program by the American College of Surgeons) expands that to ABCDE: Airway, Breathing, Circulation, Deficits in neurologic function, and Exposure (remove/cut off all clothing... easier to find injuries and wounds that way).

Also, the "C" in the old "ABC" acronym is also supposed to stand for Cerebral protection in addition to circulation. I've also heard CPR termed "cerebral pulmonary resuscitation." That's probably a fair substitution, since your main goal in CPR is to protect the brain by creating a low-flow rather than a zero-flow state (contrary to what some folks think, CPR doesn't restart the heart from a V-fib/V-tach arrest... generally only electricity can do that).

Once your brain's dead, you're dead... even if your heart, lungs, kidneys, etc are all working normally. Those folks become organ donors, or should...

Let me put in a plug here... PLEASE CONSIDER DONATING YOUR ORGANS. Please... talk to your family about it, get it on your driver's license or living will. Lots of people need organs, and if you don't need yours anymore (and you have no deep religious/philosophical objection), why not donate them? Just a thought...

Re:He's Dead, Jim.

[jburroug]

I think most paramedics would be clued in by the external battery and the power cord coming of the patients stomache that something about this patient was special. Also it's not as though people will be getting their hearts replaced with (well assisted by) these things willy-nilly they are only for people who have pretty much no other choice if they want to continue living. Also FTFA it will often be used as a temporary measure for people undergoing other treatment or who are waiting for transplants. The friends and family members of these people, the ones who might call the paramedics, will be well aware of the situation. In fact they'd probably call the cardiologist right after the paramedics in the event of an emergency who could relay special instructions. I also doubt this is a group of people that will be out in the wee hours of the morning bar hopping and getting falling down drunk.

So no this isn't a serious issue. It is, in fact, a non issue.

Re:He's Dead, Jim.

[Rob Carr]

But if you're breathing, it's safe to assume that your heart is working. That's basic physiology. And not quite true. I've had several patients without a pulse continue talking to me for a while. Looking over at the monitor revealed non-pulse producing rhythms to go along with the lack of pulse. Eventually, everyone went back to following standard physiology - one way or another. But those transients are memorable. (It's worth noting that there's a standard pre-hospital med that would cause asystole (flat line) for about 30 sec. The patient would report "feeling funny." The only problem was that patients would get upset when they'd see the heart monitor go flatline. There was a simple solution to this - we put the monitor where the patient couldn't see it.) Rob

Re:He's Dead, Jim.

[strike2867]

Actually I think it would go like this:

"ZZzzzzzzZZZZzzzzzZZ"

"Sir!"

Checks pulse "He has no pulse, start CPR."

"Get the hell off me."

"AAAAAAAA".

Re:He's Dead, Jim.

[ReTay]

"The problem is no-one's going to check your wallet for a consent card for CPR, so she's had her chest tatooed with a warning saying something like "Get thos f*cking this away from my f*cking chest. If you revive me I'll sue your arse off!". "

Kind of remindes me of my EMT instructor, She has three tattoos
There is an "X" two fingers above her zyphoid process (where you put your hand for chest compressions)
and underneath is says push here.
She has the outline of two fingers on her right wrist.
And a circle around her vein in her arm.

Lets just say that if she didn't train them she doesn't trust them.
Then again she is of the opinion that no matter how far along a woman is in labor when you pick them up in an ambulance if the baby is not born in a hospital your driver is to slow.

Re:He's Dead, Jim.

[Daniel Dvorkin]

The device you're thinking of is an AED, Automated External Defibrillator. Basically what it does is read the patient's EKG, compare it against a list of known arrhythmias, and decide whether it should deliver a jolt. I was skeptical about them at first -- being an EMT-D, i.e. an EMT with additional training to use manual defibs (and years of ER experience, not just a four-week class) I had been taught that human judgement was the gold standard -- but the fact is they've saved a lot of lives, and their judgement is often better than that of stressed-out emergency personnel.

Re:He's Dead, Jim.

[Dinosaur Neil]

What if someone is asleep or knocked unconsious?

Presumably, after indulging in an experimental and no doubt expensive procedure, I'm betting that the subject would be given a MedicAlert bracelet that would give the attending EMT a head's up...

Re:He's Dead, Jim.

[Frank T. Lofaro Jr.]

You can have a heartbeat while not breathing, but you can't breathe without a heartbeat.

Yes you can have breathing without a pulse. It is called agonal respiration.

Re:He's Dead, Jim.

[Anonymous Coward]

The process of organ donation is about as far removed from the eating a heart philosophically as it is physically.

In one case, you kill a man in an act of brutal violence, rip apart his chest, and eat the contents. The act is one of savage aggression, done not only out of the belief that life-force is absorbed, but also because the eating of another man is, in some respects, the ultimate form of degredation and dehumanization that you can subject him to.

I'd argue that the transplanting of organs can't really be construed as sucking the "life force" out of another so that one may live. Supposing that life force is indeed something real; surely, we can agree that it is not contained in the heart. If it is anywhere, it would have to be the brain. Whatever you think of the nature of our consciousness, you must agree that the brain inside our skulls is the physical container for it.

Organ donation isn't degrading to the donor or recipient. Whatever life force the former contained left him when his brain died. Perhaps you feel that it is degrading to consider ourselves as a collection of biological parts, like a machine, but with what we know today, this is demonstrably so. Further, I simply can't see why this could be construed as degrading: we are what we are.

I'm rather curious as to how you perceive the body and mind... I suppose I see them as two completely separate things, interconnected to the degree that the former must support the latter... do you feel that they are one in a sense that biology does not fully explain, and that playing mix-and-match with parts of the body does something to upset this? If so, would you argue that recipients of donated organs are made less human in the process, or are somehow degraded?

I'm quite curious as to your opinions, because you're the first person who has voiced an objection to organ donation based on something other than religious belief, distrust of the medical profession, or vaguely described discomfort with the idea. I look forward to a reply.

I'd rather have a pulse.

[Anonymous Coward]

We can't be sure what the pulse controls, plus I would like to be able to tell if I'm still alive.

What will Nurses do...

[JagRoth]

... at the Doctors office without being able to take our pulse while they stall until there is a doctor available to see us?

Re:What will Nurses do...

[Bob McCown]

I guess they'll just put a timing light on my, er, finger, and check my RPM.

Re:What will Nurses do...

[akadruid]

... at the Doctors office without being able to take our pulse while they stall until there is a doctor available to see us?
You've never used the UK's National Health Service.
The nurses don't take your pulse while you wait for a doctor in our hospitals - after 4 hours of pulse taking, they would probably not have learnt a great deal more.
And that's the emergancy patients.

Re:What will Nurses do...

[fuzzybunny]

Well, at least if it's a cute nurse, she wouldn't be able to tell you're imagining her in her undies by your speeding pulse.

On the other hand, "My net blood flow through my impeller turbine surges when I think of you" just doesn't really sound all that romantic.

Nature's solution is best in at least a few ways.

[etymxris]

...the VentrAssist is less likely to damage red blood cells because it moves the blood more slowly with a bigger impeller.

That's why you haven't seen more propellor based solutions--they tend to chop up the cells. Propellors work great on something you don't mind mincing up, such as air for planes, water for boats, and ice for that delicious smoothie. But I'd be hesitant to send my red blood cells through a propellor. I know they're talking about impellers and not propellors, but I see little difference in damage capacity.

Just imagine ...

[sebounet666]

... waking up in a coffin because someone thought you were dead :(

variable speed

[tverbeek]

How would your life be different without a pulse?

I wouldn't be able to tell how hard I'm exercising. Which brings up the point that these turbines are going to have to be variable speed if they're going to accommodate humans' varying oxygen needs.

Re:variable speed

[Tassach]

Turbines are generally happiest when running at a constant speed. However, it's not necessary to vary the turbine's speed to duplicate the heart's action -- what you really need to vary is the net flow rate. A variable net flow rate can be achieved even with a constant-speed turbine with some valves and clever plumbing.

Re:variable speed

[SargonZ]

Actually, current pacemakers can only be set to one speed, so people who have these devices already have the limitation of non-variable heartrate. While this is a setback for the pacemaker-using crowd, almost all agree that having a non-variable heart rate is better than having no heart rate at all.

Re:variable speed

[Anonymous Coward]

"almost all"?

Re:variable speed

[Kupek]

I can generally tell how hard I'm exercising by how much it hurts.

Re:variable speed

[Rogue974]

This is something I know about, I am an engineer and work with centrifugal pumps (engineering classification of these impeller/turbine pumps. You can make them variable speed and use the speed of the impeller to control the flow of the medium being pumped. There are many advantages to this, but it is not the common flow control scheme. Most of the time, the speed of the impeller is held constant and a control valve on the discharge side of the pump is opened and closed. As the discharge vale is open, flow goes up, as the valve is closed, the flow goes down. I woudl venture to guess, that the muscles that apply pressure to arteries to direct the blood flow (an everyday normal activity in all human beigns) acts as the flow control and the pump just sits at normal speed. If you have a variable speed pump, they would have to tap into the nervous system to determine the blood needs of various organs/tissues and use that as speed control, not going to happen, or give you a rheostat on your side that you coudl turn up and down the spped of the impeller based on what you were doing (sarcasm). Summary, constant speed centrifigal pump with the flow control being down by the discharge valve (this case muscles on the arteries that are already there) and the pump impeller speed never changes.

Re:variable speed

[Rogue974]

Variable speed is unecessary. Not sure if you were saying that is the way and how it works when you replied, but you don't need to vary the speed at all. The speed of the pump is set to have the ability to deliver the maximum required flow and pressure (pump sizing exercise) and then the amount of flow is varied by the muslces that contract on the artieries. In other words, the body continues ot regulate the flow/need of the blood and the pump just supplies it. THat is the way a centrifigual pump works, the impeller goes the same speed all the time and has the potential to deliver the maximum flow, but does not deliver the maximum flow until the discharge valve (in this case the muscles the constrict the arteries) are open 100%. Simply put in the pump so that the blood flow capacity is there and then the bodies natural mechanisms that already directy the flow of blood would do the rest. Variable speed is near impossible (probably completely impossible) due to the control/decisions of speed/input needs etc that we don't know how to read from the human body.

Re:variable speed

[CharlieG]

What? Almost all current generation pacemakers are rate responsive - they have a minimum rate, max rate, and rate curves, and they use various sensors (usually activity (movement) from what I understand, but also breathing rate) to change from one setpoint to another.

I've been with my Dad when they check the programming of the resting and exercise rates on his pacemaker, and set them, and the transition point - It's all done with an inductive coil that is places over the main module of the pacemaker - they can even check the settings by phone

If I had no pulse...

[garcia]

I wouldn't have to take the two different high-blood pressure meds that I do now. That would save me about $35/month and the random side effects that go with taking these medicines (shortness of breath when exercising, dizziness when getting up to fast, etc).

Pulse

[kc0re]

I heard that people without pulse get a sense of disorientation and un-equilibrium. Especially those with screw drive hearts. Since the body has operated on a pulse for so many years, I have talked to people that have these screw drive heart devices, and they initially they couldn't even sleep at night because they didn't have the pulse in their ear.

cosmetic surgery?

[mblase]

I wonder how many goth vampire wannabes will elect to have these implanted, just to improve their authenticity?

Problems

[BWJones]

There are certain advantages to having a "pulse". Examples are: The alternating low and high pressures may allow the bodies baroreceptors to better control blood pressure and there are other important feedback mechanisms associated with having alternating high and low pressures in response to the heart contracting. I would worry that some of the new pumps could undermine those mechanisms.....

Re:Problems

[BWJones]

Perhaps I should have clarified some of this for the non-biologists here. Baroreceptors are receptors found in the aortic arch and internal carotid arteries that are sensitive not only to overall pressure in the cardiovascular system, but also to rates of pressure changes which are critically important in cases where you suddenly undergo rapid loss of blood pressure. (like when you are bleeding......alot). In cases like these, your body starts a series of physiologic changes to keep you alive and interfering with those sorts of things were what I was referring to.

These issues may also be important for maintaining cardiovascular fitness as well as recovering from myocardial infarcts, and because the alternating pulse pressure is eliminated in turbine models, I would worry about possible losses of negative feedback which might result in runaway blood pressure which could lead to hemorrhagic strokes, kidney damage and other such unpleasantries.

Oh, and since the Slashdot crowd appears to be preoccupied with sex, there is some evidence that penile erections are dependant upon alternating pressures to, ahem.....get the job done.

Re:Problems

[endx7]

The again, not having a working heart at all would probably undermine those mechanisms as well...

Interesting

[The-Bus]

I wonder what kind of effect this has on the body. Think about it, it's a pretty constant stream of blood flowing, as opposed to a stop/start of a pulse. Sure, there's several (I'd say at least... 5 or 6)* pulses per minute, but if I remember seeing video of a cellular level for vessels, it looked more like a semi-congested LA highway rather than a smooth flow. My guess is you'd probably need some sort of batteryless implant that would measure blood pressure as well.

* Very technical here.

still a pulse

[uid0mako]

from the article:
"LVADs are not designed to replace the heart but are implanted alongside it under the rib cage."

Therefore your heart is still there beating. This is just a supplement to it.

You have to rtfa

[bfree]

I can't believe that the body has no problem with living without a pulse! I would have expected complicated side effects (the lack of rythm disturbing some other micro or macro cycles). Any biologists in the house care to explain how far back in evolutionary terms it is since we last had no pulse? Does nothing depend on it or do we really have the diversity in our dna to adapt to the situation?

Internal Metronome

[the darn]

Then I'd not only lack rhythm, I'd have no beat, either!
Semi-seriously, though, would this eliminate the possibility of things, uh, throbbing?

'Detecting a pulse' for those who don't have one

[EnglishTim]

A few months back I did a first-aid course at work. One of the interesting things I found out was the technique they use for checking to see if someone's heart is beating:

Basically, you pinch their earlobe. This forces the blood out of the lobe, and then you let go. If colour returns to the lobe, then the heart is beating and blood has been pumped back in. If it does not then blood is no longer moving around the body.

This technique would probably also work for those with no pulse.

Whatever You Do...Don't. Fall. Asleep.

[GoatChunks]

With no pulse, I'd be afraid to take a nap in the park. "God damn it! I'm in the morgue again!"

What would be worse though...I imagine most of the people getting these will be rather up in years. And, as old people and dads do, they will inevitably fall asleep in front of the TV.

The first 6 or 7 times they do this, their family will think they're dead and will start going through his pockets. But then it becomes a "boy who cried wolf" scenario, and they think he's just sleeping when he's actually dead. Next thing you know, ol' grandpa has funked up the Lazy Boy, and they have to take him out in a bucket.

Re:Well

[nkh]

and what about love? would we feel the same without a pulse? (not that I know anything about it...)

predicted lifespan

[sacrilicious]

They also have no bearings, so they should last much longer than previous attempts. In fact, engineers don't give a predicted lifespan on these models.

Marketer: So what's the predicted lifespan for these models?
Engineer: We're, uh, not giving one.
Marketer: Because it's so long?
Engineer: I'm sorry, I didn't catch that. And now I have to go. (leaves)
Marketer: (calling after him) I'll hold you to that!

Hmmm....

[El_Ge_Ex]

He has no pulse sir.

He's the undead! SHOOT IT! SHOOT IT!!!!!!

Re:Hmm (ex wife, but seriously...)

[kiatoa]

I'm sure someone will be adding their favorite politician to this thread but seriously - I'd put money that there will be some consequences to not having a pulse. Valves will not get the exercise they need or something. N million years of evolution (or 7 days of design if that is what you buy into) means that there are probably lots of subtle interdepenancies of a pulsating blood supply. Of course some of the consequences might well be good...

Swoosh... Swoosh... Swoosh...

[waynelorentz]

I think this has happened before (someone living without a pulse). There was some old man in Kentucky in the last year or so who was hooked up to an external blood pumping device. He was on the news because he lived for a few months, setting a record for the person who lived the longest without a heart. He was asked by a television reporter what it was like to not have a heart, and the guy said not having a pulse was the strangest thing he'd ever experienced. He said it was really really eerily quiet. Gross.

How would the body react?

[akiaki007]

Considering our veins are outfitted with nice valves that prevent the backflow of blood in between pumps of the heart, what would happen to them when they are no longer needed? One would think that they just wouldn't close, which I suppose is fine, but it just seems that they might create an unwanted side-effect.

Also, it is possible that our organs aren't capabale of handling blood in a constant stream and they need those precious milliseconds of rest in between beats.

Perhaps I should've stayed in medicine and then I'd know these answers, but since I didn't, anyone know or have a better theoretical idea?

Re:How would the body react?

[RedWizzard]

Also, it is possible that our organs aren't capabale of handling blood in a constant stream and they need those precious milliseconds of rest in between beats.

If that's the case then the problem certainly isn't a severe one. According to TFA, the six patients who have received this device were all so sick that they could not have a transplant and had life expectancies of less than a year. I'm sure those patients organs were in a pretty delicate state. 3 of them have since died, but the others are doing very well. One of them is living at home 13 months later.

As an aside, there are an awful lot of posts here looking for problems and generally being pretty negative on the whole idea. It really says something depressing about the general tone of Slashdot at the moment. I wonder if it has occurred to any of those posters that the developers will have thought of these problems too, and either solved them or determined that they are not significant?

Time to lower /. dating standards

[Mr. Neutron]

"Must have a pulse" is no longer a requirement. :-)

Re:Time to lower /. dating standards

[Vexler]

Perhaps, but let's not confuse that with "Must have a heart". ;-)

We are the Borg...

[m0RpHeus]

Too bad this came in too late for Slashdot's previous poll regarding putting yourself on a robot body. Having these means we're one sep closer to becoming Borgs.

Zombies, obviously

[SadPenguin]

I would totally mess with people. I'd hang around in busy public areas claiming to be undead (or dead, not sure which is creepier) and then when people questioned me i'd be able to prove, by traditional metrics that i am dead (no pulse). then i would try to avoid the police, because, c'mon, people get creeped out pretty easily.

Re:Zombies, obviously

[jellybear]

Omigod that is so goth it would be awesome I would be so goth.

Re:What? No MD's here?

[stephenbooth]

The golf course hasn't put in WiFi yet.

Stephen

Re:Nature's solution is best in at least a few way

[Dr. Evil]

Well yeah, but this is for when natures's solution fails. Kidneys and bone marrow solve the blood cell damage problem. :-)

I'm wondering about the little one-way valves throughout the body which aid the pulse. Does such a system damage or suffocate those valves?

Aren't there other systems in the body which depend on the pulse? Could the move to a pulseless heart make a later transplant less likely to be successful?

Oh no, the porn industry!

[emorphien]

Hmm, this could be bad for any male porn star that needs a replacement heart. Aren't the male porn stars supposed to be able to hold a throbbing erection? Now it's gonna have the distinct hum of a turbine.

Could be good, could be bad. Hmm.

Re:'Detecting a pulse' for those who don't have on

[imag0]

Well, that and the guy you just checked screaming "OW! You just pinched me fucking ear!" will probably help as well.

Re:Nature's solution is best in at least a few way

[Anonymous Coward]

Similarly, I recall seeing a documentary on this, which mentioned that the pulse may in fact be necessary to control and stimulate the growth of vessel walls. Anyone know if the opinion on this has changed?

Re:'Detecting a pulse' for those who don't have on

[Anonymous Coward]

Not a reliable indication. You'd be amazed how much peripheral circulation shuts down in patients in shock as the body attempts to maintain blood pressure in the core. At best, refill at the lobe will give you a general idea that the patient may be perfusing well, but lack of refill is certainly not an indication of pulselessness. Circulation out at the skin layer is one of the first things the body cuts back on in an attempt to combat shock.

(IMHO - however I speak from many years of experience as a Paramedic.)

Had it in the lab, years ago...

[gillbates]

When I took my freshmen chemistry courses in college, we had electronic stirs - you'd drop this plastic coated magnetic "plug" in a beaker, and then set the beaker on the machine. An alternating magnetic field would cause the plug to spin, stirring the fluid.

And now, 15 years later, someone finally figured out that you could apply the same principle to moving blood. Amazing.

I've always wondered why people bleed to death on the operating room table from trauma. When I worked as a mechanic, I had a supply of various diameter tubings readily available so I could plug a vacuum leak when diagnosing a carburetor malfunction. I've never understood why surgeons can't do the same with blood vessels - the patient is bleeding from a major artery, and it never occurs to them that the could slice the artery in half and connect the ends with surgical tubing?

I had always thought that there must be some really scientific reason for this, but now it occurs to me that it might just be ignorance. It took medical science 15 years to figure out that a lab stir would work better than bearings? I knew that as a freshmen! Ask the hubble designers - it uses frictionless magnetic bearings - maybe they could have clued someone in?

Re:Had it in the lab, years ago...

[carlcmc]

the reason many times is more ominous than what you mention. Say you're operating on a patient who has received previous radiation therapy. Sometimes the vessels will be just like butter. you can't place a stitch without it tearing. Meanwhile you're trying to pump in blood faster than they are bleeding out.

say an artery is transected and the operating field fills with blood. They are bleeding out faster than 2 suckers can handle and you can't see to stop the bleed.

say there is a arterial-venous malformation making a venous lake. The entire operating field is all blood vessels and there is no where to place a stitch that will stop the bleeding and won't cause more...

Re:Had it in the lab, years ago...

[philip_bailey]

I've never understood why surgeons can't do the same with blood vessels - the patient is bleeding from a major artery, and it never occurs to them that the could slice the artery in half and connect the ends with surgical tubing?

The answer is that vascular surgeons have been doing exactly this since the 1950s.

Common procedures nowadays include replacing part of an aneurysmal abdominal aorta with a "Dacron" graft or bypassing stenosed or occluded arteries in the lower limbs with synthetic grafts.

Re:Hmm (ex wife, but seriously...)

[EpsCylonB]

I had a very similar reaction, IANAHS (I am not a Heart Surgeon) but in the article it says...

it only has one moving part, a spinning impeller that drives a continuous stream of blood.

Surely the human body is not designed for a continuous stream of blood ?.

Saying that I am sure that this has all been researched thorougly to get to this stage and my limited medical knowledge probably isn't very useful.

Re:Hmm (ex wife, but seriously...)

[arivanov]

You are absolutely correct. If you look at the internal surface of a major vein you will notice that it it is uneven. It does not allow blood to flow back and this works properly only with a pulse flow. It will not work properly with a constant flow. So people who rely entirely on a device like this will be prone to various vein problems - varicose veins, cirrose like vena portalis deformities, etc. So devices like this cannot replace a heart 100%. At the same time they may be enough to provide assistance for a week or failing heart (this is what these guys are claiming to do anyway).
While on the subject, continuous exposure of blood to a strong magnetic field is not something that has been investigated and there may be some long term problems associated with it.

With no pulse...

[Neil Watson]

..it's time to throw out your organ donar card.

Re:Nature's solution is best in at least a few way

[howlatthemoon]

There would still be a need for the valves in the veins for stopping backflow. The venous pressure is very low. If i remember right (my last physiology course was a long time ago), most of the return flow is added by movement (muscles squeezing the veins pushing blood through the valves and the breathing cycle which causes the large veins to expand and collapse which pulls blood back to the thorax and towards the heart.

This is a very simplistic explanation as I remember it, and I haven't had much coffee yet so the old gray matter is not ticking at full speed yet.

But seriously...

[The Tyro]

the procedure is actually to assess them first... something along the line of shaking them and asking "Annie! Annie! Are you OK?"

If they answer "yes," you're done.

I realize you were only joking, but the entire clinical picture needs to be taken into account.

My favorite EMS call is the patient with a minor head injury who is rushed in with a "blown pupil." When you go see the patient, they're awake and alert, not vomiting, not somnolent, etc. It's usually someone who's new, and doesn't understand the pathophysiology behind Uncal Herniation and 3rd nerve compression.

Back to the topic at hand... I wonder if the lack (or blunting) of the systolic peak and diastolic trough in the blood pressure would lead to any physiologic problems? According to the article, the device is actually a Left Ventricular Assist Device (the ole' intra-aortic balloon pump is the classic example of such a device). It steals blood from the left ventricle and steadily pumps it into the aorta... but I wonder if it has any effect on the coronary arteries?

The coronary arteries mainly fill during diastole, when the aortic valve closes and blood floods the coronary sinuses on the aortic side of said valve... since this device essentially "steals" blood from the left ventricle and injects it somewhere downstream, I wonder if the coronaries get the same filling? (I suppose it's a question of where you place the downstream catheter.) It might not make a difference if you have clean coronaries, but if you've got a Left-main stenosis, it could be bad to drop that filling pressure...

In a perfect hydraulic system, it wouldn't matter, since pressure injected in one location would increase pressure in all locations... but arteries have compliance, and they can flex.

Interesting device... it'd be nice to know some more details.

Re:But seriously...

[magefile]

Show off ;-) But at least I know what atlantoaxial sublaxation and genu valgus are!

Red October of the Heart

[Venner]

Rock on caterpillar drive, I say. I'm thinking Hunt for Red October here.

Lol. As a former nuclear/plasma physics graduate student, it makes me laugh even more. Do you know how that caterpiller drive actually works? The field of study is called magnetohydrodynamics and is one of the most @*#%$!* involved things I've studied...

Basically, you have an electric field of some sort or readily available ions (think, salts in the ocean water), apply some strong magnetic fields of differing strength, and cause a forceful ion drift in the direction perpendicular. I just call it Evil Fluid Dynamics With 50 Other Variables.

As an aside, since there are relatively fewer dissolved salts, the Red October's caterpiller drive wouldn't work in fresh water. Neat eh? Not that there are terribly many huge bodies of fresh water where you'd worry about silent submaries. :-)

At any rate, there are dissolved salts in blood, aren't there? So you could theoretically do this for a heart pump. But who knows what the heck it'd do to the patient and I'm guessing you'd need a whole lot of auxiliary equipment.

Re:Red October of the Heart

[ultranova]

Basically, you have an electric field of some sort or readily available ions (think, salts in the ocean water), apply some strong magnetic fields of differing strength, and cause a forceful ion drift in the direction perpendicular. I just call it Evil Fluid Dynamics With 50 Other Variables

Um, no.

A magnetohydrodynamic drive works exactly like any other DC electrical engine. That is, it has an electrical conduit material in a strong magnetic field. When current is applied to that conduit, it creates a magnetic field around the conduit, and the interaction of these fields causes the conduit to experience a force.

In a "normal" submarine, you would use a copper wire as the conduit, and connect that wire to an axis to transfer the force to a propeller, which in turn would push water backwards. But in a magnetohydrodynamic submarine, you use seawater as the conduit. As a result, seawater experiences a force and is moved backwards (and the submarine experiences the counterforce and is moved forwards).

As an aside, since there are relatively fewer dissolved salts, the Red October's caterpiller drive wouldn't work in fresh water. Neat eh?

Unless the designers were smart enough to put saline injectors to the water intake valves...

Then again, tap water is notoriously conductive for electricity (or so all those bathtube electrocutions I keep hearing about would seem to suggest), so is your average river/lake really that unconductive ?

Not that there are terribly many huge bodies of fresh water where you'd worry about silent submaries. :-)

Loch Ness... Wouldn't want to wake the monster up ;).

Proof

[TheMadPenguin]

Darl McBride is living proof you can survive with no pulse.

Re:Nature's solution is best in at least a few way

[sql*kitten]

I'm wondering about the little one-way valves throughout the body which aid the pulse. Does such a system damage or suffocate those valves?

Also, the heart isn't the only pump in the body - the muscles in your legs help return blood to the heart when you run. That why if you run then stop abruptly you feel faint, because suddenly the load on your heart has suddenly increased and it needs to ramp up to pump blood all the way up to your head at a usable pressure (which is one reason you should warm down properly after exercising). How would the impeller interact with "pulses" from the legs?

Re:Nature's solution is best in at least a few way

[jdhawke]

As someone who has worked with impeller pumps for the last decade, there is going to be a significant difference in the amount of damage done to the cells. I have seen live sea-life on the output side of impeller based pumps, where a propeller style pump does as you say, chop every thing up.

Surprising

[maroberts]

IIRC, blood vessels contain a number of one way valves which open and close in response to a pulse, so I'm surprised that these don't fail and have problems in the absence of one.

Maybe the pulse is not totally absent, from the article, this only replaces half of the heart, presumably leaving the other half to pulse along as before.....

I presume that they can't really pulse the pump to truly simulate a heart operation, as that may have effects on its power consumption and reliability.

On another subject, is blood affected by magnetic fields? I just wonder if any problems are caused by the magnetic coil drive system of this thing.

Great for shooting!

[sc2_ct]

How would your life be different without a pulse?

---------------

Well, it would definately help tighten the groupings up at the shooting range. This could be a big boon to snipers :)

This would have really messed up Star Trek

[ellem]

He's Dead Jim. No wait wait he's alive.

Re:Hmm (ex wife, but seriously...)

[D3]

Actually, I read a Reader's Digest article about a similar pump a couple years ago. Some young girl in England had a viral heart infection and would have required a transplant. Instead, they stopped her heartbeat and implanted a constant pump like this. The doctors were all concerned about the effects of not having a pulse, not having 2 bounces for blood pressure measurements.

She lived quite well with the device and the stopping of her heart actually let the heart muscle repair itself. It turned out that resting the muscle was very good for it. She was eventually taken off the device and her heart restarted.

So no, there are not the adverse effects doctors had theorized about.

mdiarmspafpothama

[TamMan2000]

I had a very similar reaction, IANAHS (I am not a Heart Surgeon) but in the article it says...

it only has one moving part, a spinning impeller that drives a continuous stream of blood.

Surely the human body is not designed for a continuous stream of blood ?.

Saying that I am sure that this has all been researched thorougly to get to this stage and my limited medical knowledge probably isn't very useful.

mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate) and he agrees with you.

I told him about a woman in england that had an earlier version of one of these for several days while waiting for a real (human) heart (this was a few years ago). His imediate reaction was that pulsitile flow probably slows the build up of plaques in the arteries, and that people without a pulse would, IHNSHO (in his not so humble opinion), be more likely to experience blockages.

Of coarse that was just his gut reaction and he has not researched the topic...

Re:mdiarmspafpothama

[GPSguy]

Well, having actually spent some time doing partial and total artificial heart research, including about 6 years with the earlier LVAD (pulsatile) technology, I'm of two minds about this.

1. I don't believe we'll see increased atherosclerotic plaque deposition due to non-pulsatile flow. I'm currently subscribing to the theory that plaque is related in chronic bacterial infection of the vascular intima.
2. There was some evidence, but poorly followud up in the past, that renal function was on the short list of critical elements requiring pulsatile flow. One reason for inadequate continuing studies was that the problems with on-pump anticoagulation, infection and anesthesia tended to introduce enough variables to make isolation of the pulse issue too obscure.
3. There have been a number of reports in the past, some as long as 15 years ago, of surgeons using the Biomedicus BioPump, a similar design, for extracorporeal bridging support to transplantation, or similar to the anecdote below, to place the heart at rest to allow its recovery. I'm aware of many cases (I participated in at least 10) of multiple-day attempts, and at least 2 or 3 trials of several weeks. Realize that the patients were already moribund, so supporting them in bridging, awaiting a suitable donor, was their last and sole chance for survival. And, no, most of them didn't survive to transplant.

I'm intrigued. I'm out of the business now, but I'm convinced that we're overdue for some real breakthrough to make implantable artificial devices for continuous perfusion a viable alternative to transplantation with the limited pool of donors.

Re:mdiarmspafpothama

[Baseclass]

mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate)

You don't have to spell it out, we're all familiar with that acronym.

Re:mdiarmspafpothama

[dougmc]

His imediate reaction was that pulsitile flow probably slows the build up of plaques in the arteries, and that people without a pulse would, IHNSHO (in his not so humble opinion), be more likely to experience blockages.

Perhaps, though people should remeber that these artificial hearts are meant for people in extremely dire straights. Their life expectancy, even with the artificial heart, probably isn't long enough to allow the build up of plaques.

I noticed that the pump still has external wires for power. I thought it was generally believed that this was a bad idea, because the holes in the skin where the wires come out is a prime place for infections and such. I thought the `state of the art' was to have rechargable batteries inside, and charge them via an electromaget placed outside (basically it's a transformer.)

Re:mdiarmspafpothama

[Loco3KGT]

mdiarmspafpothama (My dad is a retired medical school professor and former president of the heart association midwest affiliate)

You don't have to spell it out, we're all familiar with that acronym.

Well now I feel like an idiot for going "em-dia-rmspaf-pothama... what the hell is that?" *click shortcut to open dictionary.com in new tab*

Re:mdiarmspafpothama

[DavidTC]

Pacemakers are just replaced, completely. As the battery lasts about ten years, and advances in technology happen during that time, it would be rather stupid to just replace the battery, especially considering you have to cut people open regardless. Plus, the ability to open a pacemaker would be another point for fluids in the body to sneak into the pacemaker.

The wires running to the heart, called 'pacer leads', are not replaced, though, so it's just a simple matter of slicing open the skin and hooking up a new pacemaker to the lead. (Usually they have two leads, so they can pick which ever one seems better, and have a backup if one breaks.)

Now, what would be vaguely useful would be a way to recharge them from outside, by induction, or, hell, body motion. They can be programmed from the outside, but not charged, which I think is stupid.

Of course, pacemakers use a lot less power than artifical hearts. Pacemakers just give the heart a very tiny shock to get it to automatically work, because the heart's natural pacemaker has been screwed up somehow. A lot of times they only have to do it every few seconds or so. Artifical hearts have to move a hell of a lot of blood continually around the body, whereas you could probably operate a pacemaker from a watch battery for quite some time.

I have some old pacemakers laying around (They give you the old one when you get a new one. Weird, eh?) and I've been tempted to take then apart to see how much is the battery. I suspect 90% of them.

Re:mdiarmspafpothama

[trentblase]

charge them via an electromaget placed outside (basically it's a transformer.)

Ok, so you've got a magnetic impeller inside as well as coiled wire to drive the impeller. Then you've got a big ass electromagnet outside... maybe this isn't such a good idea after all.

so what you're saying

[BitterAndDrunk]

"Depending on the body fat on a person, the pulse isn't always easily detected."

So basically most Americans effectively have no pulse already? I swear, we're always ahead of the curve.

Re:Hmm (ex wife, but seriously...)

[Politburo]

If you look at the internal surface of a major vein you will notice that it it is uneven. It does not allow blood to flow back and this works properly only with a pulse flow. It will not work properly with a constant flow.

But a flowback prevention device is only needed because of the pulsed flow. Without flowback prevention, blood could never reach the head as it would keep running back down the arteries as the heart cycled. As long as a continuous flow is of sufficient pressure, this problem is eliminated, and the need for flowback prevention is removed.

Re:'Detecting a pulse' for those who don't have on

[EnglishTim]

Apparently the reason they now teach this method is because it's more reliable for those who haven't had a great deal of training - i.e. most First Aiders.

Obviously the pulse check is only used after you've already checked for breathing.

You might be right

[TheLink]

The thing about a pulse is the blood vessel valves need only open at the peak pressure of the pulse. The rest of the time the blood pressure can be quite low. On average the blood will still flow the right way.

Whereas for a pulseless heart the blood pressure has to be at the peak continuously.
There are also other issues to do with general plumbing - I read somewhere that heart surgeons have found putting a slight twist in a bypass vein makes it less likely to clog up. Theory is that it causes the blood to swirl and that could help keep the vessels clear and healthy. I can't find the original article (New Scientist) but you can read about it here.

Quote: "They discovered that the smooth shear stress caused three genes to become more active (New Scientist, Science, 5 October 1996, p 17). Two of these code for enzymes that reduce blood clotting and protect cells from damage. The third gene produces a protein vital for the synthesis of nitric oxide, which inhibits the development of thrombi--blood clots--and prevents the surrounding layer of smooth muscle cells from overgrowing the endothelial layer. But the activities of these genes were barely detectable in cells that felt turbulent shear stress or no stress at all. Some stress, it seems, is a good thing. "

So without a pulse it is likely that the cells may not behave correctly.

Well at least you might have some fun with the old-style lie detector tests :).

BP and pulse are issues

[coyote_oww]

A lot of hospitals use automated blood pressure and pulse equipment to keep tabs on patients. Currently, this equipment can sound an alarm to attract the attention of a nurse if BP or pulse gets out of whack.

So... it appears we'll have to come up with a new way to measure blood pressure, particularly. Presumably, the best way to do this is to fit the turbine with inlet and discharge pressure sensors, and a flow meter. Step 2 is to establish some sort of numbers for what is "normal" for turbine heart patients.

This ups the ante for health care professionals by a bit. Not only do you need to know normal ranges, consequences, and treatments for standard BP and pulse ranges, you would need to be familiar with turbine pressure and flow ranges as well.

Re:Hmm (ex wife, but seriously...)

[Anonymous Coward]

Only arteries have a pulse. The blood flow is as follows: heart -> arteries -> capillaries -> veins -> heart. By the time the blood gets thru the capillaries to the veins the blood pressure is vastly reduced and the pulsatile flow generated by the heart is not felt in the veins. Hence veins do not have a pulse. The valves in the veins have nothing to do with the pulsatile flow of the heart and hence a constant flow heart will not affect the functioning of the veins in any way. Venous problems like varicose veins, cirrose like vena portalis deformities are not related to how the heart pumps.

Oh well...

[Jedi Holocron]

I just got a nifty heart monitor for running. Guess I should just go eBay it now...

Mechanical or Cloned Heart? Decisions,decisions...

[Phoenix666]

I have a low LVEF (Left Ventricular Ejection Fraction). A couple years ago while jogging I suffered a tachycardia (extremely rapid heart rate) that had me at around 300 beats a minute for 45 minutes. They gave me a defibrillator, but said that it was possible that the drugs might not be able to stop the decline of my LVEF and would require a heart transplant. Heart transplants are extremely hard to get, btw. Basically, if you need one, you're screwed.

So to me, this device looks pretty darn cool. The cloned hearts grown from your own cells method is also pretty darn neat. The prospect of being an actual Borg is enticing, but the reservations about secondary effects of not having a pulse do give one pause. Yet if going with a cloned heart encourages the cloning of other organs, then perhaps that would be a better way to go. Decisions, decisions...

Re:'Detecting a pulse' for those who don't have on

[Lord Bilbo]

Basically, you pinch their earlobe. This forces the blood out of the lobe, and then you let go. If colour returns to the lobe, then the heart is beating and blood has been pumped back in. If it does not then blood is no longer moving around the body. Now, what would happen to the person who gets this no beat heart? Will the heart continue to operate (not beat as we already know) after the person dies? If so, this test would show that circulation is still taking place!!! The person wouldn't be breathing, so the ear may turn an odd shade of blue when blood returns to the ear. I think this would confuse the hell out of the person expecting the color to be more of a pink, huh? Sorry for the morbidity of my further thoughts on this assumption:

1. Now, let's say that they determine that the guy with one of these hearts dies. If the heart just continues to operate, things could get
2. messy when he gets to the morgue! And the mortician may have some psychological problems after cutting open a dead person have having blood flow out of its body instead of just leak out since the artifical heart is still operating.

Before I go any further, I'll stop.

Loud Pulse?

[abb3w]

Um, I have NO medical training, but wouldn't your pulse being loud enough to hear be a sign of #$%^& high blood pressure... which would contribute to conditions that might need a heart replacement?

I wouldn't know; In high school, my BP tended in the uncomfortably low 80/50 range... which caused at least one school nurse much consternation, as she couldn't find my pulse in wrist or throat. "Dear, are you sure you're breathing?" Since getting out from my mother's obsessively healthy "low salt/low fat" cooking, I've achieved a more normal 100/70 normal BP.... but I still don't hear my heartbeat.

no pulse, no school?

[!splut]

Alas, some poor soul might not meet the primary requirement for our nation's great vocational colleges.

Re:Hmm (ex wife, but seriously...)

[StalinsNotDead]

I'm no medical proffessional, but isn't blood pressure measured by listening for the pulse while constricting the flow with a sphygmometer.

How would blood pressure be measured without this reference. Like air pressure in tires?

Re:Hmm (ex wife, but seriously...)

[GPSguy]

When you place the heart at rest, you remove the load it sees, and use an artificial pump to do the work.

You don't stop the heart. Even today, with cardioplegic solutions significantly advanced, supplemented with NAD-compounds and amino acids, stopping the heart bears the significant risk that you can't get it restarted again.

Cardioplegia for cardiac surgery involves infusing a potassium-rich solution into the coronary arteries, which stops the heart in diastole. Further, the solution is cold, and the heart is bathed in an iced saline slush to cool it further and diminish its metabolic requirements. At this point, the heart is *NOT* getting a blood rich perfusion (barring the use of blood-based cadioplegia, which I'm still not sure is as good an idea as some others think) medium.

If you were to start reperfusing the arrested heart with blood, with a normal electrolyte composition, the extra potassium would be washed out, the heart would rewarm, and if it has sufficient energy stores, and a sufficiently normal physiology, it would begin to contract again.

So: To put the heart at rest, you unload it, keep the blood chemistry as normal as possible, maintain good nutrition status (parenteral alementation), and see if the heart muscle recovers.

Military will be all over this.

[GR|MLOCK]

Now their snipers won't have to worry about firing in between heartbeats. Anybody want to bet on how long it'll be before we have black-ops cyborg snipers with no pulse?

Pulse-less-ness observed in cardiac-bypass

[Anonymous Coward]

Cardiac bypass, used commonly during a CABG (coronoary artery bypass graft) operation, involves an external pump, pumping blood around the body after gas exchange has occured outside the body (ie. carbon dioxide removed and oxygen added, plus some other bits'n'pieces). (Bypass is required during CABG because the operations are commonly performed with the heart 'stopped' for 30-60 minutes while the surgeon attaches the grafts. 'Off-pump' CABGs are sometimes performed where the surgeon operates on the beating heart, avoiding the need for bypass).

Anyway - the bypass pump commonly delivers continuous (ie. non-pulsatile) flow, even though most modern machines have the capability to deliver pulsatile flow. Research is somewhat inconclusive as to whether there is any disadvantage in delivering non-pulsatile flow in this setting, although in most situations where someone has poor kidney function the machine will be set to deliver a pseudo-pulsatile flow, in an attempt to mimic the normal physiology.

The rationale here is that some (inconclusive) research suggests that the kidney's may be damaged by non-pulsatile flow. As the kidney's receive such a large proportion of cardiac output (25% !), it;s wouldn't be surprising.

I would be surprised if a non-pulsatile flow didn't throw up some unexpected problem - but also, my time as an anaesthetist (or anaesthesiologist in the US) continually demonstrates the impressive adaptability of the human body!

(and regardless, being on bypass does all sorts of unpleasant things to the body, independent of the presence/absence of pulsatile pressures.)

As commonplace as pacemakers?

[maydog]

From the ventracor website:

"The VentrAssist(TM) LVAS has the potential to become as commonplace and reliable as pacemakers."

That seems to be a pretty bold statement considering that implanting one of these is a pretty invasive procedure and that the implant leaves you with wires penetrating the skin leaving a path for infection. This technology combined with the AbioCor (did I get that right) transdermal battery would be pretty cool.

I also do not see any valve in the design, so if the battery were to fail, the heart would not be able to pump.

There are pacemaker / defibrillator (CRT) devices on the market today that offer, long term, effective treatment for several types of heart failure (see the new england journal of medicine), they require a minimally invasive procedure, are completely implanted - no external wires, and the heart maintains some pumping ability in the event of a device failure. Also, the patient regains a quality of life and independence that you could not have with worrying about keeping your batteries charged and wires protruding from your abdomen.

The design of the device is novel and very interesting and , without a doubt, will benefit a small population of patients. I am waiting, however, for the next generations of treatments that target the tissue and biology repsonsible for the pathology. Gene therapy, stem cells, etc. offer greater hope and better long term outcomes for patients. Pumps are only for sustaining until something better can be found.

Re:Hmm (ex wife, but seriously...)

[baxissimo]

> (IMAD) I am a doctor.

Good thing your patients' lives don't depend on your ability to create acronyms. ;-)

Whole Heart Version?

[Xesdeeni]

I saw this technology in a documentary on PBS at least fifteen years ago, but it was for a full heart replacement. They were reviewing artificial heart research after the Jarvik-7 was implanted. The odd thing was that the show went into a bit of detail about a centrifugal pump and its power supply, but I haven't seen anything about it since then.

Apparently a small nuclear pellet was used in the battery, which was in a lead-lined container about the size of half a D-size battery. The battery could be implanted completely, unlike the Jarvik, which requires a dangerous (susceptible to infection) tube running through the skin to a suitcase sized pneumatic pump. The issue they focused on was the danger of the radioactive pellet. Apparently concern had been raised about the possibility of an artificial heart recipient being in a plane crash. The fear was that the radioactive battery would leak. So they went to great pains to test it, including shooting it out of a gun, to show it was safe.

IIRC, the concept of being without a pulse, and the need for more research about this, was mentioned almost as an afterthought. But I've wondered ever since then what happened to this type of artificial heart. A completely self-contained apparatus would seem to be a godsend. But I always assumed that lack of pulse was the gotcha.

I even discovered that Marilyn Vos Savant, whose Q&A column appears each week in the national Parade insert to many Sunday newspapers. is married to Robert Jarvik, and consdered writing him in care of her about this device. But I never got a round tuit.

Xesdeeni

Does anything depend on a pulse?

[Theovon]

Did you know that many clocks depend on your outlet current being exactly 60 (or 50) Hz? In the US, I believe federal regulations dictate that over some specified period of time, your wall outlet has to count to the right total number of oscillations. When load is high, causing the generators to spin slowly, the cycle count can get off by minutes, and the electric company has to make up for in off-peak periods by running the generators faster.

In biological systems, we often see unusual dependencies. I think I read somewhere that certain birds can't swallow without gravity. And why not? It's there! Make use of it! That's the way evolution works. Nothing is more redundant than it needs to be (well, we can talk about transposons later). In humans, bone density is dependent on load, which is why our bones atrophe in weightlessness.

So, given that we HAVE a pulse, I would be surprised if some part of your body didn't take advantage of it.

Re:Hmm (ex wife, but seriously...)

[lucifuge31337]

While I mostly agree with you, I have one nit-pick/addition. As a former meat wagon operator (oh, sorry...I mean paramedic), checking for blood flow in extremities can be done by checking capillary refill as well.

Huh? Yeah...push on your fingernail. The nailbed turns white. The time it takes to go back to pink/red is your capillary refill time. Should be 1-2 seconds max, or you've got problems....not necessarily low bp....dehydration and low o2 saturation will do it too.

That being said, no pulse....how the hell do I get a BP? I'm guessing my pulseox won't work either. Do they have an LCD control panel mounted on their chest so I can check and adjust their BP with a little screwdriver? I can see this type of thing really compilcating/confusing emergency medicine.

Living Without A Pulse

[Doc Miller]

I develped a pump for extracorporeal circulation of blood back in the mid 1970's and had to take a lot of these problems into account. My pump was pulsitile and had a very physiologic wave form including dichrotic notch. It also had 2 orders of magnitude less damage to red blood cells than the best pumps on the market at the time. (at least with the cow blood I experimented with) (Read on for an explanation of this) After spending a lot of money on patent lawyers, the device got shelved when I couldn't get a clear patent on it. I think people here on slashdot are missing the point of continuous (non-pulsitile) flow. The elasticity of the arteries especially the aorta actually adds to the pulsitile nature of blood flow. There is an artifact seen in blood pressure measurements called the dichrotic notch that is a direct result of this. If it is absent it is an indication that hardening of the arteries has taken place. The main purpose of circulation is to get blood to tissues and organs. Once there, it has to infiltrate the organs deeply in order to properly transfer oxygen and nutrients and carry away wastes. We were evolved with pulsitile flow and as a result the perfusion of organs and tissues is better with this type of fluid dynamic. That doesn't mean it won't work with constant flow, only that it won't be as efficient. It may take several years before these inefficencies result in some kind of problems. An increase in plaque deposition comes to mind because the tissues arent stretching and contracting. The other problem with turbines and impellers is the "waring blender effect" where the blood cells are "chopped up" by the spinning blades. This leads to hemolysis (release of hemoglobin into the blood form broken red blood cells) which puts a strain on the kidneys which aren't beilng perfused properly because of the non pulsitile flow, etc. etc. you get the picture. Anyway, it's interesting but not a permanent solution.

no heartbeat?

[gordona]

I can see it all now. Two lovers holding each other close. One says to the other: "I love to listen to the whirring of your heart!"

Re:Nature's solution is best in at least a few way

[Hungry Student]

I remember seeing a documentary about this a few years ago and yes, the fact that prop/impellers chop stuff to bits was a big problem for the doctors working on the project. However, they used very sophisticated modelling and milling techniques (I think the term "developed for the space industry" was banded about) and managed to produce a design that didn't mulch the red blood cells.

Re:Evolution?

[dupup]

"If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down." (i.e., an irreducibly complex system)

A classic example of [potentailly] irreducible complexity is the bombardier beetle. It's a funky little critter that, when annoyed, shoots steam out its ass. The tricksy part is how it manufactures that steam without exploding.

The bombardier beetle has been used by creationists as an example of intelligent design, i.e., something this complex could not have evolved, but must have been created.

I fall on the evolution side of the fence, but, I have to admit, it's definately a thought exercise to imagine how this little dude developed his superpowers through evolution.

Re:Evolution?

[Schmucky The Cat]

How does this creationist claptrap instantly get modded up for spouting off some Michael Behe irreducible complexity nonsense?

Creationist claptrap doesn't need to get peer reviewed to get published (and then subsequently spouted off on internet message boards). But since creationists like to talk about bacterial flagellums people have gone to the trouble to write peer reviewed published articles refuting the claptrap.

Is there some conspiracy of bible thumpers that come along and comment on slashdot biology threads and then up-moderate their co-horts or are there really enough fucking stupid slashdot readers that really think arguments like "irreducible complexity" have interesting merit?

Apologies...

[Orne]

If your heart is still contracting and it is not connected to the bloodstream, does it make a sound?

My dad had no pulse during heart surgery and

[Sethseekstruth]

..He could not get his sleep rhythms right for about a year, which the doctor who operated on him said was common, so no pulse may mess up your sleep cycles.

This was when they used a blood circulation device when his heart had to be worked on

Plausible explanation

[Peter Millerchip]

You said: Can anyone offer a plausible explanation for how any one of the pieces of a bacterial flagellum would offer that bacterium some sort of advantage?

Why yes, I think we can!

A nice quote from the conclusion: ...the very fact that a step-by-step Darwinian model can be constructed that is plausible and testable significantly weakens the suggestion that extraordinary explanations might be required.

Nice try though...

Re:Evolution?

[shlashdot]

Thanks for posting that. Stuff like that is why I studied embryology, biomechanics, and evolution.

Unfortunately, this statement:
"While there may be circumstantial evidence to support either a continuous or discontinuous model of life, it is vitally important to recognize how one's starting assumptions affect one's conclusions."
is, in my opinion, typical of those made by people who have not studied biology but somehow can't come to grips with their beliefs being, um, wrong. There is no circumstantial evidence, or any other kind, for the discontinuous model. Sorry.
I admit I cannot draw you a picture of the stages in the evolution of flagella, but the more you study a variety of cellular phenomena you realize that there is only one possibility that is remotely self-consistent. Natural selection and evolution.

Re:lack of pulsatile flow and coronary vessles

[henryhbk]

I am an internist, but we deal a lot with cardiac surgery patients.

A major problem with continous flow would seem to be the diastolic part of the cardiac cycle (when the heart is refilling) is critical for back-flow from the body (arteries do not have valves) into the coronary artieres (the arteries that feed the heart). The aorta (main artery from the heart to the body) is elastic, so a large bolus (fluid surge) of blood is ejected into the aorta, stretching the aorta during systole (contraction of the heart). When the heart then relaxes (diastole) the stretched aorta recoils, and squeezes blood both forward and backwards. The heart has an output check valve at the aorta (aortic valve) which prevents it from completely flowing back; however a small takeoff (the sinus of valsalva) allows the blood to surge into the coronary arteries, and since the heart is relaxed, flow all the way to the muscle of the heart. I don't know if someone has looked into coronary blood flow during these continous pumps, but it might be useful to see, since these hearts are in bad enough shape without becoming ischemic (oxygen starved)

Re:Holy crap !

[beetle496]

You guys are not looking hard enough. Artificial heart was surgeon's last hope of saving Julie's Life

If you rest a torn muscle, it gets better. We thought if you could find a way of resting an acutely sick heart it might get better too

For six extraordinary days Julie Mills, a 21-year old student, survived in a hospital bed with no pulse and no heartbeat.

As she prepares to go back to college, almost fully recovered and take her place in medical history, her doctors have described how an artificial heart kept her alive, pumping her blood smoothly through her body in a continuous flow.

Her own heart, swollen and inflamed because of a virus infection, was allowed to rest completely and, as the cardiac experts hoped, it was simply given time to recover.

Classic example of creationist dishonesty

[Abies Bracteata]

........ This is not flamebait... lol...

Well, this is a well-deserved flame.

...In fact, run over to your library (bookshelf?) and grab a copy of Darwin's book "On the Origin of Species..." and turn to page 162. Read the section about the mousetrap. Darwin concludes that "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down." .....

Darwin doesn't even mention mousetraps in the chapter from which the individual whose propaganda you are parroting lifted this passage.

It's pretty clear that calebb is just another not-so-honest creationist who has taken (probably nth-hand) out-of-context a passage from a book he's possibly never even seen. Even if he has seen it, he certainly hasn't read it for comprehension.

Now, let's look at the rest of that passage, shall we? (emphasis added)

If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, round which, according to my theory, there has been much extinction. Or again, if we look to an organ common to all the members of a large class, for in this latter case the organ must have been first formed at an extremely remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has passed, we should have to look to very ancient ancestral forms, long since become extinct.

We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; thus the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire

It's absolutely appalling to see such worthless rubbish like calebb's post here modded up to a score greater than -1.

BTW, "On the Origin of Species..." can be found in its entirety on-line at http://www.talkorigins.org/faqs/origin.html.

Speed boost

[btwIANAL]

So, who do you think will be the first to overclock one of these. I can see it now:

Yeah my heart runs at 100 RPMs, but you see this button. If i'm ever in danger I just push this button, and wham up to 7200 for 20 seconds.

Re:lack of pulsatile flow and coronary vessles

[afidel]

Uh, isn't the entire point of these pumps to REPLACE the damaged heart? I mean if you have a low maintenance pump with little chance of failure why are you relying at all on the failing/failed natural heart?

Re:Evolution?

[kilfarsnar]

The page linked to Intelligent Design actually goes on to refute the idea that the Bombardier Beelte is an example of inteligent design. It is quite plausible that the beetle developed it's defense mechanism through natural selection.

Chronic bacterial infection?

[The Tyro]

I'd appreciate a link to that... I've been doing this for a long time, and I've never thought that belief was widely held. I've heard of theoretical links between C. pneumoniae, but that's about it (of course, C. pneumoniae has been theoretically linked to all kinds of things, including Chronic Fatigue Syndrome, among others).

I'd say the classical risk factors for heart disease still hold; smoking, hypertension, diabetes, the bad gene (usually a triglyceride or cholesterol metabolism problem), etc. This really isn't a flat-earth-round-earth debate... Any new theory had better be pretty compelling, particularly with the mountain of research backing up the standard risk factors.

The "bacterial infection" guys may turn out to be right... but they're going to have to prove it.

Re:Chronic bacterial infection?

[chadjg]

My dad has to take some pretty hefty doses of antibiotics before any dental work. Apparently he has some minor heart valve issues and the bacteria from his mouth can get into the blood stream when the dentist is doing his thing and cause havoc. Does this have anythign to do with what you are talking about? Is the dentist just covering his butt?

Re:Chronic bacterial infection?

[The Tyro]

No. Your dentist is actually doing the right thing.

Your dad has a valve problem in his heart, and dental work does cause a transient bacteremia (bacteria being released into the bloodstream). Most of the time your immune system will clear out those bacteria, no problem... most of the time.

If you have a damaged heart valve, those bacteria can infect the valve, leading to a condition called Bacterial Endocarditis. The bacteria grow on the valve, and can destroy that valve, as well as throwing infected bits downstream in your circulation, leading to brain abscesses, kidney and lung infections, and general sepsis.

Endocarditis is a nasty, nasty condition... probably most of the cases I've seen were IV drug users. It's a hell of a life; some of those folks will shoot up anything they can find, regardless of what's in it (ie. foreign material loaded with bacteria). Also, when they are re-using needles, the needles will eventually dull, and sometimes barb (painful!). To detect a barb, addicts will sometimes lick the needle tip, then shoot up if no barb is felt with the tongue... you can see where I'm going with this. The human mouth is only slightly less dirty than the human anus... they end up injecting tons of bacteria, and develop Endocarditis. To make matters worse, they never go to the doctor, except when they try to scam more narcotics, or inadvertantly overdose. By the time they do show up, their valves are shot, and they're almost dead. If they survive, they end up needed open-heart surgery and valve replacement.

Anyway, that's probably more than you wanted to know... but as far as dental procedures go, the antibiotics your dad takes are effective in preventing Endocarditis. He'd be well-advised to keep taking them as prescribed.

I don't think the original poster was referring to Endocarditis though... I'm fairly sure he was referring generally to Atherosclerotic Disease.

Re:lack of pulsatile flow and coronary vessles

[cellocgw]

Blood will always flow if there's pressure behind it (doh). I'd expect, based more on physics than any experience in cardiology, that a continuous flow at maybe 100mm (well below common systole) would work just fine without overstressing any part of the system.
But if future studies were to show that a pulsing system really does something useful, it shouldn't be too hard to put a controller chip that has the impeller spin up and spin down at some reasonable rate.
BTW, just because it's different from nature doesn't mean it's harmful. For example, it may have taken 50 years (largely due to politics) but it's now considered medically safe for women to take continuous contraceptives and go without menstrual cycles for all or most of the year.

Old Science Show . . .

[Dausha]

I recall an old science show that said that the pulsating pressure was actually important for the human body. As I recall (and it's been nearly 20 years), the pulse helps the blood travel down certain pathways it couldn't reach under a steady push, and that it gives the body more time to transfer the goods, so to speak, intra-pulse. The discovery was made because the old dialysis machines delivered steady stream and they learned that not all the blood was circulated (some pooled).

Not that I'm 100 percent sure about this. I like my ticker. I mean, with a non-pulse heart, if I were to pass out, they'd think I was dead.

You're referring to adenosine

[The Tyro]

or Adenocard (trade name in the US).

It can induce asystole for a few seconds... I've never seen it last for 30 seconds.

Patient reports of the adenosine experience vary greatly. Some don't mind it... others would rather have you cut their heart out than get adenosine. I'll never forget a biker guy I saw a couple of times for recurrent SVT (SuperVentricular Tachycardia). He hated adenosine (though it always worked); said it made him feel like he was dying. He was a great big muscular tattoo-covered man, and would cry like a little baby when you brought out the drug, literally weeping in terror.

To see a grown man reduced to that... my heart really went out to the poor guy.

Re:You're referring to adenosine

[Rob Carr]

I left the name off. I figured that some would know what I was talking about, most wouldn't care, and there's a few folks 'round here that might use it to wind up on the 11 o'clock news doing a "perp walk."

I've got a copy of at least one strip with 30 sec. of asystole in between SVT and NSR. Finding it would be the trick. The one I wish I'd have kept was from the guy in fine v-fib. Arrest witnessed by physician who didn't know CPR, down 5 minutes, when I called "clear" his eyes bugged out, he sat up and tried to strangle me. Scared the folks I was with, but I was more concerned with keeping my thumbs off the little red buttons. He screamed "NO!" in my face. After we pried him off me, we shocked him and got him back. Fellow actually woke up in the hospital...with no memory of why he'd yelled "NO!" I've always wondered....

I never had anyone respond that way to Adenocard.

Unsedated cardioversion is a completely different story.

"Sir, you're not going to like me after I do this."

"That's ok. I don't like you now."

Evolution doesn't favor turbines? ERRR wrong

[Robert1]

Planaria have a unique system for excreting nitrogenous wastes. They have a secondary circulation system called a protonephridium, which consists of a connected system of "flame-bulbs." They essentially look like bulbs, with slits on the sides. At the top is a cap cell, which has cilia that descend into the hollow bulb. The cilia constantly spin, drawing water continuously, like a turbine, from the interstitial fluid through the slits. The reason they're called flame-bulbs is that the constant spinning of the cilia resembles a flame.

Re:Evolution?

[venomkid]

Irreducible complexity/intelligent design don't even pass muster under the most basic requirements of scientific inquiry and logic.

Affixing the word "theory" or "science" to them doesn't help. They predict nothing, they tell us nothing.

Marine snipers could take longer shots

[osjedi]

My pulse is my biggest hurdle when taking high-power rifle shots at long rages (>600 meters). Without a pulse I could hold steady on a much smaller target. If you've never shot a scoped rifle, your pulse makes the crosshairs bounce with each heartbeat. You can slow your heart-rate down and time the beats, but it would still be nice to be able to hold steady on a 1,000 meter target and not have any movement. If you get excited it all goes out the window - if your pulse quickens you might as well be riding on the back of a horse.

I imagine there are other tasks besides shooting that are impacted by pulse. I'm sure there are types of micro-surgery for example that could be negatively impacted by the surgeon's pulse.

Mean Arterial Pressure

[steelheals]

I'll bite: I'm not golfing because I don't have the patience. IAAS (I am a Surgeon) and it would not be that difficult to measure a continuous flow generated pressure instead of a pulsed pressure. Plus you wouldn't have to teach us about turbines and such. For example, currently a patient in the ICU may have their blood pressure measured with an indwelling arterial line rather than a transduced cuff. We follow Mean Arterial Pressure (MAP) in this setting. Here's a quick definition: http://www.globalrph.com/map.htm (It was easier to google than find a textbook but this is short and sweet)- "Equation: MAP = [(2 x diastolic)+systolic] / 3 Diastole counts twice as much as systole because 2/3 of the cardiac cycle is spent in diastole. An MAP of about 60 is necessary to perfuse coronary arteries, brain, kidneys. Usual range: 70-110." We could still measure the equivalent of a MAP with a continuous pump. Some of the bioengineers who commented above probably know better, but whatever the range of pressure in the system from continuous pumping (whether it's always the same or if there's a smaller variation than the normal systolic/diastolic) it could still be accounted for and easily monitored and used to guide therapy. Probably the bigger problems are those already mentioned: baroreceptors that will now be in a new range, changes in coagulation, and destruction of blood borne cellular elements.

Athletic performance

[michael_cain]

One of the factors that limits performance in athletic contests such as the recently completed Tour de France is cardiac output -- how much blood the rider's heart can pump. Fifty years from now will we have to have rules against riders with artificial hearts because they have an unfair advantage in cardiac capacity? Or will we borrow the kinds of regulations that the various auto racing organizations impose on engines? You can have an articial heart, but volume pumped must be constrained to be below X liters per minute, or the outlet into the aorta must be less than some number of square millimeters?

A valid fear

[The Tyro]

in some countries... I believe China still harvests organs from prisoners.

In the US there's so much oversight that I can't see it even being possible. Many transplants aren't even done in-house... the organ gets flown to where it needs to go (I've flown on a couple of those... you get to jump to the front of the line on the taxiway, even if there are 30 planes waiting to take off).

Seriously, there are so many ethical questions, paperwork to be filled out, different physicians involved... declaring someone brain-dead and pulling the plug is a big deal, even more so if it's an equivocal case; it requires multiple physicians to sign off, consultation with the family (and their physician), appropriate consultations and diagnostic testing, and often a review from the hospital ethics committee. Hell, half of the doctors that sit on those committees don't even like one another... they just tolerate each other. There's NO WAY they'd all agree, in some nepotistic star-chamber fashion, to something as evil as wrongfully terminating someone's life and harvesting their organs. No way.

I can't see that caper ever being pulled off and not coming to light.

Re:lack of pulsatile flow and coronary vessles

[PsiPsiStar]

Perhaps you're right regarding contraceptives and tinkering with human systems, but the reproductive system is one system that can be tinkered with or even removed without too much harm to the rest of the body (re: castrations and all). Especially after puberty. I'm not sure if this is the best proof if you want to make a general argument.

Re:Hmm (ex wife, but seriously...)

[Soruk]

Another problem that could occur... imagine if said transplantee were involved in an accident, and he got hurt, was unconscious. The first thing the rescuers would do would be to look for a pulse. On not finding one, would probably pronounce the victim dead at the scene and make no attempt to rescue him and get proper medical attention.

Re:Evolution?

[greg_barton]

A mousetrap has five essential pieces - and if any one of them is missing (i.e., the spring, the hammer, the catch, the platform or the holding bar), the trap will not function.

And yet we have the Venus Flytrap.

No pulse....

[thewiz]

As someone who was born with a congenital heart defect, has had three surgeries, and has been ticking with an artificial valve for the last 22 year, I'd be worried about not having a pulse.

One of the things doctors/surgeons have noticed with heart patients that have their hearts stopped is that they lose all sense of time. I noticed it after my surgeries. I don't know if anyone has done research into the beating of the heart and the mechanisms in the brain that allow us to perceive the passage of time. Does the beat of the heart interact with the area(s) of the brain that perceive the passge of time? Do other bodily processes require a heartbeat for a "timeing signal"? I'm sure there are other questions to ask about this subject.

Show me a man with a song in his heart and I'll show you a man with an AM/FM pacemaker!

Re:No pulse....

[aswang]

This is an interesting idea which sounds plausible. It's well known that our circadian rhythm is driven by pulsatile activity of our pineal glands, as well as certain nuclei in the brain. And reproduction is impossible without pulsatile release of GnRH (gonadotropin releasing hormone) from the hypothalamus. In fact, menstrual cycles can be stopped by providing a continous level of GnRH, whereas a pulse of GnRH will restart them again. Where do these pulsatile mechanisms in the body derive their timing from? What if it's from the heart? After all, the heart is one of the earliest organs that start functioning in the embryoobstetricians generally use the lack of a heartbeat on ultrasound as a sign that a miscarriage has occurred. Who knows what pulsatile processes will be driven out of whack by eliminating cardiac pulsatility?

Ahhhh . . . peaceful hangovers, at last!

[kmankmankman2001]

No more of that pounding thunder in my head!

Re:lack of pulsatile flow and coronary vessles

[bloggins02]

Well I'm not an internist, or a researcher, and my dad was definitely not a heart surgeon.... ... but I did stay at a Holiday Inn Express last night.

So I think I'm qualified to say this is bad, and that you should initialize the hydrogen recombiners before even attempting this procedure.

Link to PDF containing exploded detail...

[choovanski]

No one has linked to this yet? Are you kidding me?

Just in case you missed it, fascinating stuff. (Possible complications aside)

http://www.ventrassist.com/news/VentrAssist.pdf
from
http://www.ventrassist.com/product/descrip_ cont.ht ml

It's a "donation," not an auction

[The Tyro]

it's called organ "donation" for a reason... it's also called an anatomical "gift." You're giving somebody else life, with something you no longer need; it's strictly voluntary...nobody's going to force you.

So You're going to die and bury that organ... yet you're going to try to scratch and scrabble for that last thin dime, even as you die? You refuse to take part in a process that benefits others, simply because you cannot benefit yourself? No streak of altruism? Not one iota of selflessness in you? You were given life... yet you insist on being paid for giving others life, via something you were just going to throw away to rot?

Hmmmm... I'm guessing I won't be seeing you volunteering down at the homeless shelter much... suit yourself.

Warning!

[Paracelcus]

Tattoo on chest: Do not use defib, subject has no pulse, subject may not be dead, please call 1-888-heartless for more information.
Or call On-Star!

Have you heard of the scientific method?

[beetle496]

You have it exactly backwards. The theory of evolution is just that, a theory. This is how science works. One postulates a hypothesis. Only if it is useful, that is, it furthers our understanding, and allows testing against, is it kept. Theories that are not testable, like intelligent design, are not scientific, they are matters of faith. Theories can easily be proved false, all one needs is a single concrete counter example, but being mere theories, they are never quite proved true. If after years and years of being tested (and not once being false), and continuously demonstrated as being useful, theories are accepted as fact. The creationists like to put this backwards: concluding that since scientist cannot prove evolution, the competing model (ID) is on equal footing. ID is faith, it is by definition not testable, and it is not useful in science. You can feel free to believe it you wish, but your conclusion is not based on logic. Scientific models, laws even, do not have to be fully understood to be useful. The effects of gravity, for example, are well understood -- and we have plenty of equations for it -- even though science hasn't quite explained where gravity comes from (except that it is an intrinsic feature of mass). Gravity isn't mentioned in the Bible, so the religious nuts don't feel compelled to manufacture un-testable competing theories.