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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?"
How would your life be different without a pulse?
I would have had much more in common with my ex-wife.
Trolling is a art,
FTA: "The pump also has a curious side effect: people implanted with the device have no pulse."
/dies
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!!!!"
The dangers of knowledge trigger emotional distress in human beings.
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.
http://alternatives.rzero.com/
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.
I wonder how many goth vampire wannabes will elect to have these implanted, just to improve their authenticity?
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.....
Visit Jonesblog and say hello.
I guess they'll just put a timing light on my, er, finger, and check my RPM.
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.
- First they ignore you, then they laugh at you, then ???, then profit.
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...
90% of the wealth is in 2% of the pockets. Bummer to be in the majority.
"Must have a pulse" is no longer a requirement. :-)
dinner: it's what's for beer
The golf course hasn't put in WiFi yet.
Stephen
"Don't write down to your readers, the only people less intelligent than you can't read" - Sign on Newspaper Office Wall
Well, that and the guy you just checked screaming "OW! You just pinched me fucking ear!" will probably help as well.
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?
He's Dead Jim. No wait wait he's alive.
This
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.
Do really dense people warp space more than others?
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...
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
So basically most Americans effectively have no pulse already? I swear, we're always ahead of the curve.
You better watch out, there may be dogs about . .
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.
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.
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.
Never ascribe to malice that which can adequately be explained by tenure.
> (IMAD) I am a doctor.
;-)
Good thing your patients' lives don't depend on your ability to create acronyms.
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
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.
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.
Do not fold, spindle or mutilate.
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.
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...
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)
Well, this is a well-deserved flame.
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.
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.
https://app.box.com/WitthoftResume Code: https://github.com/cellocgw
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.
-=-=-=-=- osjedi uses Debian GNU/Linux. -=-=-=-=-
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.
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.
Even if a man chops off your hand with a sword, you still have two nice, sharp bones to stick in his eyes.
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.
Even if a man chops off your hand with a sword, you still have two nice, sharp bones to stick in his eyes.