I had a girlfriend with a similar device attached to her (an LVAD). At first it was a little unnerving seeing her unplug the batteries that were keeping her alive and charge them every night. It quickly became normal for me. Life with it seemed relatively normal except she had to have a purse with her at all times (it carried the batteries).
The interesting part was when she received a transplant and went cordless. After being attached to it for two years and not having a heartbeat the sound of her heat beating kept her up at night for a couple of weeks. I hadn't even considered the beating of a heart to be relevant to our daily lives until she had mentioned it once she heard hers beating again (an LVAD is just a constant velocity pump. The blood is always flowing).
Not sure how much it really adds to the conversation other than an interesting anecdote.
Do you have any idea if there have ever been studies on the effect of constant flow vs peristaltic flow on the circulatory system? I wonder if the constant flow creates or solves any issues.
I don't know the current state of the art, but there are definitely studies (the keyword is "pulsatile"). For example:
For comparison, here's a picture of some LVADs. The one I've seen in person (after it had been taken back out!) is the one on the far left. Flow issues aside, I can imagine the smaller ones are easier on the patient in general, just from the perspective of surgery trauma.
Current popular models are continuous flow rotors that are much smaller (enabling their use in almost anyone) and are non-pulsatile.
However, there's been a big push to move towards pulsatile devices. This is mostly driven by mechanobiolgy studies that show that there is a difference in the cellular programs of cells that are exposed to a continuous shear force versus a pulsatile shear force. Accordingly, to more closely replicate the natural physiology of the heart, there has been a big push towards using pulsatile devices.
The audible heartbeat is from the heart sliding in the pericardium sac when it beats, many people lose the audible heartbeat after having heart surgery when the pericardium sac has to be cut or removed completely e.g. if someone is having a bypass surgery.
Thanks for the great explanations!
Do they mean that blood pressure is stable too, since you presumably wouldn't have a diastolic reading - no pressure reduction between beats, since there are no beats?
When you usually measure blood pressure you increase the pressure to a value that's likely above the systolic value of the patient (say 180). Then you gradually release pressure. Once you hear a heartbeat that's the systolic value. Once you stop hearing the heartbeat that's the diastolic value, which is the vascular walls resisting the heartbeat
In this particular case instead of the usual heartbeat you'd likely hear something more like a constant flow but you'd still have systolic and diastolic values.
With a blood pressure cuff, what you are doing is collapsing the arterial wall with outside pressure. You increase the pressure above systolic blood pressure and then gradually reduce it until you hear a sound. This sound isn't the heartbeat, but is instead the result of turbulent flow in the blood vessel. While you are between systolic and diastolic pressure, only spurts of blood can flow through the vessel creating noise. Eventually, you reduce the pressure enough and blood even during diastole (which is lower pressure) can expand the walls of the artery against the blood pressure cuff.
So, in both cases what you are hearing is due to blood pushing open the vascular walls.
So that's how doctors do it with a manual pump and stethoscope. Never thought of asking one ...
Actually, watching a video, it looks like the tubes are for air maybe? Weird device in any case.
Reminds me of that procedure where a surgeon can freeze you, drain your blood, take out all your organs and then put them back in, stitch you up, pump blood back in and then warm you up and awaken you. It was like unplugging your PC, taking it apart and then putting it together and turning it back on.
edit: forgot the link!
I suspect they want to minimize the blood's contact with anything because blood likes to clot, so doing it longterm without blood thinners might not work so well.
That's what is so amazing about this device: All other devices before it threw off so many clots they killed the patient rapidly.
Lookup "Jarvik" for some of the history.
One problem ER docs see periodically is the CO2 "sensor" can become broken in patients with chronically high blood CO2 levels, i.e. people with certain types of COPD. They only breath when their blood O2 levels are low, and if you give them oxygen they just stop breathing.
We do have a hypoxic respiratory drive, but it is exceptionally weak, and unconsciousness will occur before any noticable distress is noted.
The hypercapnia alarm response we're all familiar with is tied to carbon dioxide levels, not oxygen.
Also search for “exit bag”. You’ll find instructional images, as well as an instructional video made for the sick and elderly, about using this technique to commit suicide.
I don't know why it's not universally used. I suppose it's some combination of tradition and a belief that executed criminals should suffer.
That's probably not a major asphyxiation risk unless you're trapped in a room with it, though, because, unlike inert gases like helium or nitrogen, sulfur compounds are irritating as hell - a UPS boiling its batteries will send you fleeing for the nearest source of fresh air, with eyes and nose streaming, before it'll suffocate you.
CO2 buildup is what drives the panicked "I can't breathe" response. If there's no CO2 buildup and no oxygen, it's a rapid and apparently peaceful lights out.
It's surprisingly loud
That would drive me crazy, but hey you get to live.
It starts with the Jarvik-7 artifical heart from the 1980s (first seen as a success, then as a failure) and then moves on to today's temporary and permanent artifical hearts.
- these new SynCardia artificial hearts are basically the same as old Jarvik-7 hearts (part that goes inside patient's chest), save for different sizes available today
- just the external part is now more modern (thanks to advances in power sources they can be now portable)
- big problem with Jarvik-7 at those earlier times were infections and blood clotting (leading to strokes), but doctors today know better how to manage this (as far as I understood, this is not due to better mechanical design of the heart but due to better medication / monitoring / protocols compared to ~30 years ago)
- these new SynCardia hearts were used for already ~1,600 patients (as "bridge" while waiting for heart transplant)
- FDA approved trial for use of these artificial hearts as permanent solution (no heart transplant needed), the first patient already got implanted this heart for permanent use
Not having a heart doesn't change his mood, his mood changes the heartbeat.
That's why there were so surprised he could play sports - without that acceleration he might not have enough bloodflow for his activities.
I wonder if it has a knob to manually adjust the flowrate.
Or maybe since it's mechanical it's fine for it to run at max at all times? That might not be good for the rest of the vascular system though.
If that's bad for the vascular system then an idea would be to measure O2 saturation in the toes, and adjust the flow if it gets low.
Note, I'm a lay person, and have no clue. Just pondering.
The above seems to be what Cheney was outfitted with.
The syncardia system mentioned in the article appears to be a full heart replacement unit.