On a Monday morning, it's MORNING EDITION, from NPR News. I'm Steve Inskeep.

In Your Health on this Monday, we take you to new frontiers of heart research. In a moment, we'll look at attempts to turn stem cells into heart tissue. First, the search for the perfect artificial heart.

After decades of trial and error, surgeons remain stymied in their quest for a machine that doesn't wear out, break down or cause clots or infections. Surgeons in Texas say they've developed a machine that could avoid all that with simple whirling rotors. It's a heart that has no heartbeat.

Carrie Feibel at member station KUHF in Houston has more.

CARRIE FEIBEL: For years, doctors believed that any artificial heart would have to mimic the real heart. It would have to pump rhythmically, squeezing and relaxing. After all, having a heartbeat, a pulse, is what it means to be alive.

But Dr. Billy Cohn at the Texas Heart Institute says we should just forget all that. To prove that it can work, he takes me inside the animal research laboratory to meet Abigail.

Dr. BILLY COHN (Texas Heart Institute): Good girl. She jumps up because she wants water.

FEIBEL: Abigail is an eighth-month-old calf with a soft, brown coat. Cohn and his partner Dr. Bud Frazier removed her heart and replaced it with two centrifugal pumps.

Dr. COHN: If you listened to her chest with a stethoscope, you wouldn't hear a heartbeat. If you examined her arteries, there's no pulse. If you hooked her up to an EKG, she'd be flat-lined.

FEIBEL: The pumps spin her blood and move it through her body.

Dr. COHN: By every metric we have to analyze patients, she's not living. But here you can see she's a vigorous, happy, playful calf, licking my hand.

FEIBEL: In March, after practicing on 38 calves, Cohn and Frazier felt confident enough to try their device on a patient. They chose Craig Lewis, a 55-year-old who was dying from amyloidosis. The disease causes a buildup of abnormal proteins. The proteins clog the organs so much that they stop working. In Lewis' case, his heart became so damaged, doctors said he had only 12 hours left to live. His wife Linda said they should try it.

Ms. LINDA LEWIS: He wanted to live, and we didn't want to lose him. So, you know, you never know how much time you have, but it was worth it.

FEIBEL: Lewis worked for the city of Houston. He helped maintain the city's vast system of wastewater pumps. In his garage at home, he dabbled in woodworking, metalsmithing and what Linda calls general piddling around.

Ms. LEWIS: He would go into his shop and create or fix or modify something to make it work.

FEIBEL: That's what his two doctors did, too. Linda says her husband appreciated how the doctors cobbled together the pulse-less heart from various materials. Again, Dr. Cohn.

Dr. COHN: Dacron on the inside and fiberglass impregnated silicon on the outside. Here's a little titanium piece that we machined that goes on here.

FEIBEL: Cohn and Frazier didn't start totally from scratch. What they did was hook together two medical implants known as ventricular assist devices. A ventricular assist device has a screw-like rotor of blades. The spinning screw pushes the blood forward in a continuous flow.

Thousands of people have one of these implanted near their hearts, including former Vice President Dick Cheney. But by using two, the doctors replaced both the right and left ventricles the entire heart.

Ms. LEWIS: They said do you want to hear it? And they put their and I listened, and it was a hum, you know, which is amazing. He didn't have a pulse.

FEIBEL: The doctors say the continuous-flow pump should last longer than other artificial hearts, and cause fewer problems. That's because each side has just one moving part: the constantly whirling rotor. But Cohn says they'll still have to convince the world that you don't need a pulse to live.

Dr. COHN: We look at all the animals - I mean, insects, fish, reptiles and certainly all mammals - and see a pulsatile circulation. And so all the early research and all the early efforts were directed at making pulsatile pumps.

FEIBEL: But when you think about it, there's only one reason why blood must be pumped rhythmically, as opposed to continuously. It's for the heart tissue itself.

Dr. COHN: The pulsatility of the flow is essential for the heart, because it can only get nourishment in between heartbeats. If you remove that from the system, none of the other organs seem to care much.

FEIBEL: After the implant, Craig Lewis woke up and recovered somewhat. He could speak and sit up in a chair. But then he began to fade as the disease attacked his liver and kidneys.

Ms. LEWIS: Amyloidosis is horrible. I could see the other organs were not cooperating.

FEIBEL: Lewis lived for more than a month with the pulse-less heart. When he died in April, it was because of the underlying disease. His doctors say the pumps themselves worked flawlessly.

Ms. LEWIS: We knew if it wasn't a success for Craig, if they could get data that would help them, if it helps the next person, then you did good.

FEIBEL: Biomedical companies around the world are still trying to perfect a pulsing artificial heart. But Cohn says they're like the last buggy-whip manufacturers: They're fine-tuning a product that will soon become obsolete. But he's sympathetic, too. The history of invention is full of such dead-ends.

Dr. COHN: When man first tried to come up with machines that flew, he looked around and saw bats and birds and butterflies and mosquitoes everything had wings that flapped.

FEIBEL: But what works for Mother Nature often isn't the only mechanical solution or even the best one.

Dr. COHN: When they saw that you could create wind, and that wind over a fixed wing was a great way to provide lift, then the whole field shifted. I mean there are very few flying machines in modern times that have flapping wings. And I think this is the same intellectual leap in pumping blood or pumping fluids.

FEIBEL: It will take a lot more to bring a continuous-flow artificial heart to the market. The doctors will have to decide on a final design, find a manufacturer, and get FDA approval. Even though there's more work to be done, Dr. Bud Frazier says he's confident the pulse-less approach will win out in the end.

Dr. FRAZIER: These pumps don't wear out. We haven't pumped one to failure to date.

FEIBEL: The tradeoff, of course, is the loss of the primordial ba-bum, ba-bum of the human heart. But for these surgeons that's a small poetic price to pay to make medical history.

For NPR News, I'm Carrie Feibel in Houston.

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