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Artificial heart  (Source:
Currently, 50 calves and three humans are using the pump, which completely replaces their natural hearts

Researchers from the Texas Heart Institute have successfully replaced the human heart with a 10,000-RPM artificial pump, which leaves its patients with absolutely no pulse.

Popular Science described the artificial heart, which doesn't resemble an organic heart by any means. Currently, 50 calves and three humans are using the pump, which completely replaces their natural hearts.

Drs. O.H. "Bud" Frazier and Billy Cohn of the Texas Heart Institute in Houston are the creators of the artificial pump. It is able to fully replace the heart and even provide a continuous flow of blood throughout the body -- all without having to recreate a pulse.

Creating an artificial heart has been difficult up until now. Many have tried to make a metal and plastic heart that is capable of beating, but many were unable to continuously beat beyond an 18-month period. Also, metal and plastic have many limitations, such as the requirement of an air compressor outside of the body where a hose through the skin allows the compressor to fill a balloon inside a chamber, which pushes blood to the lungs. The other balloon inflates and deflates in an alternating pattern with the other to recreate the heart's beating rhythm. This is exactly what the Jarvik-7 -- the first machine to replace the human heart -- did in 1982.

There have been other devices, such as the HeartMate ll, which is an Archimedes' screw that assists failing hearts with magnets implanted in the axle and an electric coil in its case where a charge makes its way around the coil, moving the screw at 8,000 to 12,000 RPMs. The axle spins on a synthetic-ruby bearing, which is lubricated by blood, and it's all connected to a portable battery. But the HeartMate ll can't replace the heart entirely.

Cohn and Frazier's continuous-flow left ventricular assist device (LVAD), however, can replace the heart and doesn't require a compressor because the researchers discovered that recreating the pulse wasn't necessary. The trickiest part to creating an artificial heart was recreating the pulse, but Cohn and Frazier found that just using a continuous-flow heart solved the issue of longevity, which is the main issue. One of the turbines used in the artificial heart has been running in a lab continuously for eight years, and it runs on a small battery that the patient can easily carry on their shoulder.

Cohn and Frazier described a recent process where the LVAD was placed in a calf named Meeko, who lived on to lead a normal life. However, he didn't have a pulse whatsoever, which didn't seem to be a problem. Cohn performed the surgery by peeling tissue from around the heart and allowed a heart-lung machine to take over. The heart was cut free, and continued to beat outside of the body. Cohn then sewed collars of rubberized Dacron onto the atria. He then lifted the turbines from a dish of saline with the dolly dresses dangling from them. The dolly dresses were sewed onto the collars, and the turbines were activated.

“That’s what heart surgery is,” said Cohn. “It’s a script. To you, it probably looked like I was just sewing those collars into Meeko’s chest any old way. But every motion was planned, tested, practiced. Turn my hand eight degrees and poke the needle through; swivel my hand back 22 degrees and draw the needle up four inches; turn my hand back just so and bring it to the left a half inch: a precise number of stitches, pulled just so tight and no tighter. What heart surgery takes is remembering an incredibly long and complicated script and following it exactly, step by step.”

Source: PopSci

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RE: Blood pressure?
By Solandri on 3/5/2012 9:48:13 PM , Rating: 5
I wonder if this will reduce peak blood pressure. That alone could prolong lives by reducing the chance of aneurysms or other high blood pressure related issues.

I wouldn't be so sure. Other biological systems operate off of cyclic stresses. Bones for instance strengthen and weaken in response to repeated stress and relaxation cycles, not constant stress. At a microscopic level, tiny segments of the bone literally break under stress, and the repair process builds them thicker than they originally were, strengthening them. Simultaneously, the body is also eating away at all bone to recycle calcium. Consequently the bones which aren't being stressed end up with a net loss of strength. Astronauts who spend a lot of time on the space station have to deal with this bone loss when they return to Earth.

If the strength of blood vessel walls works the same way, the lack of peak blood pressure wouldn't necessarily result in a lower chance of stroke or aneurysm. Yes the peak pressure would drop. But it could also result in the vessel walls becoming weaker, and consequently more likely to burst under a pressure spike (like, say, lying down in bed).

RE: Blood pressure?
By bupkus on 3/6/2012 12:42:32 AM , Rating: 2
If the strength of blood vessel walls works the same way
I have a naturally low blood pressure. My systolic is what some others might call their diastolic, often 90 over 65. Would this mean my arteries get insufficient strengthening? Would people with high blood pressure have a responsive strengthening of their arteries and hence not need medications for treatment of their condition? You get what I'm saying?

RE: Blood pressure?
By dark matter on 3/6/2012 2:58:24 AM , Rating: 3
You are missing his point that even you low blood pressure fluctuates. Thus stressing and relaxing your blood vessels.

This would not happen with a constant flow. They would, in affect, not be used properly as they were designed, and so would likely result in atrophy.

RE: Blood pressure?
By Gondor on 3/6/2012 7:39:19 AM , Rating: 2
Precisely ! And this should be the real concern. Blood vessels can and do ruputure on their own, but does this constant pressure operation alleviate the problem (by avoiding pressure peaks) or does it worsen it (by making blood vessels weaker due to lack of "training") ?

RE: Blood pressure?
By JediJeb on 3/6/2012 3:46:43 PM , Rating: 3
Actually your blood vessels expand and contract more due to stress chemicals than just the pulsing of the heart beat. When you have high blood pressure, even though you are getting the pulses you are not strengthening your blood vessels but leading to a "hardening" of them. The constant stress of the higher pressure stiffens the blood vessels which is not good. The least amount of pressure you can have that will still cause sufficient flow is the best situation.

RE: Blood pressure?
By WLee40 on 3/6/2012 2:53:32 PM , Rating: 2
Very good point. I remember reading somewhere that vessels require the pulsations to remain strong which is why research on artificially grown vessels uses pulsatile flow.

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