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Artificial heart  (Source: popsci.com)
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: Hmm..
By fleshconsumed on 3/6/2012 9:34:22 AM , Rating: 2
Don't you mean between taking breaths of air? Typical resting heart beat in a healthy male is between 40 and 60 beats per minute, that's one every 1-1.5 seconds, too fast to time your shot between heart beats.


RE: Hmm..
By 91TTZ on 3/6/2012 10:38:15 AM , Rating: 2
quote:
Don't you mean between taking breaths of air? Typical resting heart beat in a healthy male is between 40 and 60 beats per minute, that's one every 1-1.5 seconds, too fast to time your shot between heart beats.


Typical resting heart rate for a male is 60- 100 bpm. 40-60 is usually only found in athletes or people with problems.


RE: Hmm..
By Solandri on 3/6/2012 2:40:30 PM , Rating: 3
quote:
Typical resting heart beat in a healthy male is between 40 and 60 beats per minute, that's one every 1-1.5 seconds, too fast to time your shot between heart beats

No, it's between heartbeats. I used to do that all the time when taking handheld photos in low-light, before they came out with image stabilized lenses. You can brace your arms against your body to eliminate their motion (using the much larger mass of your torso as a stabilizer). But you can't stop your heart from beating. The camera movement due to your heartbeat is pretty obvious when hand-holding a mild telephoto like 100mm.

You train yourself to relax and your heartbeat lowers to around 60-70 bpm, and there's just enough time after the beat to snap the picture. The rule of thumb is you need a shutter speed of about 1/f.l. to avoid camera shake in a handheld shot, so with a 100mm you'd expect to need 1/100 sec or faster shutter speed. But I was regularly able to get clear shots down to 1/30 or 1/15 sec.


RE: Hmm..
By JediJeb on 3/6/2012 3:53:32 PM , Rating: 2
Yes, it is definitely between heartbeats for a gunshot. If you get much over a 4x scope on a rifle you will be able to see your pulse as the cross hairs move. Lying down prone helps but if shooting while resting your arms on your legs you will see it very well. One guy I know prefers to do up to 300 meter shots using non-optical sights simply because he is not distracted by this using them where he would be using a scope.


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