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Artificial Heart Recipient Has No Pulse
laggist writes "A heart patient in Singapore has been implanted with an artificial heart that pumps blood continuously, allowing her to live without a pulse. From the article: '... the petite Madam Salina, who suffers from end-stage heart failure, would not have been able to use the older and bulkier models because they can only be implanted in patients 1.7m or taller. The 30-year-old administrative assistant is the first recipient here to get a new artificial heart that pumps blood continuously, the reason why there are no beats on her wrist.'"
The story is light on details, but an article from last year in MIT's Technology Review explains a bit more about how a pulse-less artificial heart works.
The easiest way of moving a fluid is with a fan. It's trivial to make an artificial heart that works like that, but it has a disadvantage; the fan blades damage the blood cells. A few devices that work like this have been around for a while for emergency use (e.g. if the heart stops in the middle of an operation), but they can't be used for more than a couple of days without killing the patient (having a few blood cells killed is generally better than having no blood flowing, so they're fine for short-term use). I don't know how they solved that problem for this machine.
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Most of these artificial heart patients end up dying of strokes, caused of course by blood clots. It's theorized that such clots are easier to form in a pulse-less environment of steady-flow than in an environment where the blood is being "shaken" a bit, ie the pulse with each heartbeat.
occultae nullus est respectus musicae - originally a Greek proverb
Speaking as a biomedical engineer, there are no significant systems that we know of that require a varying pressure of blood to function correctly. The pulse as the blood gets pumped stretches the arterial and capillary walls slightly, but that's about it. Very few cells in the body experience the effects of the pulsing pressure to begin with, and those tend to be ones that can function despite the pulse rather than because of it.
Signatures are the new names.
Automated external defibrillators, such as the Physio-Control LifePak 500, will only administer a shock if they detect a valid shockable rhythm, i.e. ventricular fibrillation. This AED will not shock anyone or anything that does not have that rhythm present.
Manual external defibrillators, such as the Physio-Control LifePak 12, which may only be used by EMT-I or EMT-P (Paramedics) in my home state, can be used to administer a shock regardless of the presence or absence of any cardiac rhythm. This requires a manual override, and from what I have seen, is used even less often than the precordial thump.
Cardiac compression is the thin end of the wedge; Defibrillation would be real bad news.
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This device is bladeless. In fact, one of the major advantages of this artificial heart compared to the traditional ones, is that this damages less blood cells than all other artificial "pulsed" devices. It has other benefits, like smaller size and less energy consumption. Overall, it's a greatly improved system.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
***Well, for one, how do these people get their blood pressure measured?*** Good question. It would appear they don't -- at least not with a sphygmomanometer that depends on the Korotkoff sounds generated by cutting off pulsating blood flow. And they won't have a pulse either. Those characteristics would normally be symptomatic of being dead. Or maybe one can pump up the blood pressure cuff and listen for a single -- hopefully loud and distinct -- thunk when blood starts flowing. OTOH, not having a pulse or measurable blood pressure beats all hell out of having a pulse and not being functional. I can't imagine what they are going to put on her MedicAlert bracelet.
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
She is holding a Heart Mate II pump...most of our patients get this model...and NONE have a regular pulse. Funny since this is just breaking news and St Lukes Heart Transplant do it day in and day out, for a loooong time.
When the only tool you have is a hammer, every problem looks like a nail
the technical term for those wondering (this is/. afterall) is paristaltic pump
Breathing. One of the checks is not just a pulse, but breathing as well.
We're all hypocrites. We all have hidden parts, it's the contrast between them that make us more a hypocrite than others
According to the MIT write-up, you still have blood pressure. The device would pump more or less blood based on your body's need at the time. What you would NOT have is a systolic/diastolic reading. You'd have one pressure reading. No more 110/70 reading, perhaps a 85mmHg in its place.
The article (the second link) specifically mentions that the flow rate increases when the return rate increases meaning that yes, it can keep up, and may even out-perform her old heart in terms of flow.
-- Adam McCormick