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We have the technology
March 2, 2014 6:40 PM   Subscribe

A new 3D printed membrane acts like an artificial pericardium to continuously monitor and regulate the heart's beating
posted by T.D. Strange (23 comments total) 15 users marked this as a favorite

 
As I understand this, the membrane has some sort of scheme that tells it what the normal heart should be doing, and it will use certain tactics to restore the heart's normal rhythm when the heart malfunctions. I assume it can tell the difference between sleeping (on the one hand) and increased physical activity (on the other hand), and it won't bother the wearer during naps. Or sex.

Are we very far from having a device that can actually replace the heart? If this device can make a defective heart behave, why not just pull out the defective organ and put in a smart pump?
posted by mule98J at 7:17 PM on March 2


As I understand the article, it requires a 3D scan of the specific patient's heart to function? As in, not just a generic human heart's 3D model?

Do noninvasive scans offer enough resolution for that to be practical? Or would they have to 3D scan the heart somehow via surgical means?
posted by mccarty.tim at 7:26 PM on March 2


It's possible we got much closer to a practical, completely artificial heart when it was discovered that replicating the pulse of a heart is not necessarily important allowing for much simpler and therefore reliable devices to be used instead.
posted by WaylandSmith at 7:26 PM on March 2 [3 favorites]


Do noninvasive scans offer enough resolution for that to be practical? Or would they have to 3D scan the heart somehow via surgical means?

The device has only been developed on animals, human trials take years and years, I doubt they've crossed any of those bridges yet.
posted by T.D. Strange at 7:32 PM on March 2 [1 favorite]


I should've included a link to the Nature abstract. The full article is behind an extremely expensive academic paywall.
posted by T.D. Strange at 7:33 PM on March 2 [1 favorite]


replicating the pulse of a heart is not necessarily important

So some day I might be able to get elective cosmetic heart surgery to give me a double heartbeat, like Doctor Who? Sweet!
posted by XMLicious at 7:48 PM on March 2


Huh. I wonder what kind of 3-D printer they used. Anyway, good to know that scientists in my hometown are taking seriously my desire to become a Robotron by 2084.
posted by limeonaire at 9:50 PM on March 2 [3 favorites]


Also, re: "We have the technology": "We have the tools, we have the talent..."
posted by limeonaire at 9:55 PM on March 2


In effect, a super sophisticated pacemaker and cardioverter... pretty amazing.
posted by Pantengliopoli at 10:21 PM on March 2 [1 favorite]


Haven't we had artificial hearts for a few decades? Hasn't Cheney been using one since his corpse was re-animated after his second heart attack, back in '84?
posted by five fresh fish at 11:05 PM on March 2 [1 favorite]


As I understand this, the membrane has some sort of scheme that tells it what the normal heart should be doing, and it will use certain tactics to restore the heart's normal rhythm when the heart malfunctions. I assume it can tell the difference between sleeping (on the one hand) and increased physical activity (on the other hand), and it won't bother the wearer during naps. Or sex.

Are we very far from having a device that can actually replace the heart? If this device can make a defective heart behave, why not just pull out the defective organ and put in a smart pump?


Existing pacemakers/defibrillators have the ability to distinguish between normal rhythms and arrhythmias, as well as normal-but-slow or normal-but-fast rhythms. They have very sophisticated monitoring on board, and they're not usually trying to keep the patient's heart rate within a very tight range. It's more a matter of making sure nothing dramatic happens, and nudging the heart back towards a normal rate/rhythm when it gets a little out of whack. I'm sure this won't be approved for humans until it's got a similar level of sophistication in the heart rate detection and treatment.

As an example, my defibrillator notes whenever my heart rate goes below 50 or above 140. It rarely gets below 50 -- only 3 times in about 10 years, as a matter of fact, and only when I'm sleeping. If it stays low then it'll pace me a little to speed it back up, but that kind of pacing is painless and usually unnoticeable. It certainly wouldn't wake me up.

When it gets above 140 but is in normal (sinus) rhythm [sinus tachycardia, if you want to get technical about it] it'll record the episode but not treat it. If, however, it's at 145 and abnormal rhythm, then it will treat my heart to try to bring it back into rhythm. First it'll do what's called overdrive pacing, where the pacemaker actually tries to speed up my heart to get it under control before bringing it down safely -- I think of it kind of like steering into a skid, getting control, then steering back out. If that doesn't work, then I get the shock that's like a kick in the chest. Or if my arrhythmia's sufficiently out of whack the defib may just go straight to the shock.

My electrophysiologist (doctor with an electrical engineering degree, so in charge of my electrical system; known in the trade as "electricians" while regular cardiologists are "plumbers") has the ability to adjust my heart rate thresholds based on my own history and physiology. My defib threshold used to be at 150, I think, but then I had a series of tachyarrhythmias (fast irregular heartbeat) that were hovering just under 150, so failed to be treated. They had left my threshold fairly high since I'm young and can safely exercise, but it turns out that with my medication my heart rate rarely rises above 125 even during vigorous exercise. If it's in the 140s I probably have a problem anyway, so it was worth lowering the threshold. Since we lowered it I've had a couple of episodes where the defibrillator recorded a high pulse rate but didn't zap me because it was a sinus rhythm -- and when we looked at the records, I could actually remember what I was doing (hauling luggage and moving boxes) and that I had forgotten to take my medication on those days.

As far as replacing hearts with artificial organs, hearts are amazing hunks of muscle. Scientists do a great job of replicating some of the functions of a heart, but they haven't yet gotten anything that's as good -- in terms of safety, longevity, ability to dynamically adjust to circumstances, and minimal interference with a patient's life -- as even a fairly weak human heart. LVADs (left ventricular assist devices -- not artificial hearts, but pumps that take some of the load off a weak heart) are amazing, but they require the patient to have major surgery, undergo fairly intensive training, carry around battery packs, etc. It limits where and how much they can travel, and it even requires special equipment to take their pulse. My cousin's husband has one and it's been a new lease on life for him -- he was literally ready to lay down and die a couple of years ago, and now they're traveling and doing all the things he loves, so I'm a huge fan, but it's still a treatment best suited to those who are very very ill and not able to be rehabbed medically. Artificial hearts are improving, but again have the battery issue (surgery to replace them every 5 years is dangerous and expensive), the risks of rejection, and they still can't match all the subtle functions of the heart.

FTR, Cheney had an LVAD for some time and now he's got a transplant heart. Do *not* get cardiac ICU nurses talking about his transplant unless you've got some serious time to kill....
posted by katemonster at 12:19 AM on March 3 [32 favorites]


Thanks for the excellent and insightful comment, katemonster.
posted by marienbad at 1:45 AM on March 3 [3 favorites]


XMLicious: "So some day I might be able to get elective cosmetic heart surgery to give me a double heartbeat, like Doctor Who? Sweet!"

Go for a full on Cat heartbeat.
posted by Mitheral at 2:00 AM on March 3 [1 favorite]


The longer term future might now be, not in artificial stuff, but in using stem cells to make your own heart grow or regrow what it needs, mightn't it?
posted by Segundus at 2:53 AM on March 3


Do noninvasive scans offer enough resolution for that to be practical? Or would they have to 3D scan the heart somehow via surgical means?

Both CT scans and MRI scans can be used for high-resolution 3-D reconstruction with appropriate gating techniques.
posted by TedW at 5:29 AM on March 3


I'm looking forward to the first cease and desist order...

From katemonster's comment - I wonder why the artificial hearts have internal batteries and not, for example, a lead that runs to the armpit where a battery can be tucked under the skin instead of buried in the chest...
posted by sodium lights the horizon at 5:41 AM on March 3


To be clear, the article doesn't state that the elastic membrane was produced by a 3D printer. Instead, the mold used to shape the membrane was a 3D-printed model of the heart. Equally useful to be sure, but not what this post claims.
posted by rlk at 6:12 AM on March 3 [1 favorite]


One of the things that keeps artificial hearts from being anywhere near as good as the real thing is the difficulty in producing something that responds to all the endocrine signals and adrenergic regulation that muscle tissue is subject to. You've got the stuff we understand pretty well but can't effectively measure in-situ, and then a whole bunch of phosphorylation signaling that we don't really have a grasp on yet.

Muscle seems simple, but it is actually one of the harder organs to understand as a result of the internal stresses it deals with. Those stresses are now looking like even they are playing a regulatory role, but we really don't know.
posted by andorphin at 7:31 AM on March 3 [2 favorites]


From katemonster's comment - I wonder why the artificial hearts have internal batteries and not, for example, a lead that runs to the armpit where a battery can be tucked under the skin instead of buried in the chest...

Skin penetrations are infection vectors, and an infection vector straight from the outside of the body, through the pericardium and to the heart is very bad news indeed.
posted by atrazine at 7:55 AM on March 3 [2 favorites]


Well, plug ins do have certain issues. I had a few, of the plumbing variety, with chemo. One was the PICC line, the other was the center-line catheter. They each have their good points, and share the infection vector as a risk factor.

I was thinking about how we are regulated by an endocrine stew, and I can't even imagine how to get a machine to deal with this. Okay, I can imagine it, but it gets sort of Frankensteiney. Or maybe Matrixy.

Plumbers and electricians. Yeah. For a long time I've thought of surgeons as mechanics of a high order, and marveled at what they are able to do. Now it's time for the electricians to shine, I guess. The next step seems to be training the chefs who will flavor our endocrine stew: grow an new heart, and feel good about it.

Just spit-balling here: but would it be possible to place a rechargeable battery in a sac somewhere, with the leads affixed just under the skin? The idea here is to put the recharger onto the skin, and conduct a low current through the dermis to the leads. You could plug in at night while you watch the Super Bowl. The biggest drawback I see here would be trying to explain it to the guys at airport security.
posted by mule98J at 8:56 AM on March 3


Inductive charging might be what you're thinking of. As mentioned in the Wikipedia article, it's already used for charging surgically implanted batteries for medical devices.
posted by XMLicious at 9:40 AM on March 3


Armpit? Why not use the natural plug-in port — the bellybutton?
posted by five fresh fish at 10:24 AM on March 3


I'm curious about how the plan to implant such a device. Will they split the sternum and open the chest? Seems pretty radical for a pacemaker. They probably are thinking of using some sort of endoscope placement, but that would still be much more invasive than a current pacemaker implant. In fact, some companies are working on tiny devices that are completely contained in the right ventricle eliminating the need for leads or a subcutaneous pocket. This thing would have to have fantastic performance to compete with existing and soon-to-be technology.

OTOH, the precision offered by this technology would be just the thing for more complex situations, where aberrant conduction often leads to sustained ventricular tachycardia or even fibrillation and therapy directed by this device could head them off. Beats the heck out of a 32J shock from your implanted defibrillator knocking you flat should it fire when you're conscious.
posted by Mental Wimp at 12:01 PM on March 3


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