New heart uses parts from cows
Updated: 2013-07-28 08:29
By Anne Eisenberg(The New York Times)
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Scientists have long searched for a durable artificial heart that can work as efficiently as the one supplied by nature. Now, an artificial heart that a French company has fashioned in part from cow tissue will soon be tested in human patients.
Surfaces in the heart that touch human blood are made from cow tissue instead of artificial materials like plastic that can cause problems like clotting.
"The way they've incorporated biological surfaces for any place that contacts blood is a really nice advantage," said Dr. Joseph Rogers, an associate professor at Duke University in Durham, North Carolina, and medical director of its cardiac transplant and mechanical circulatory support program. "If they have this design right, this could be a game changer," lessening the need for anticoagulation medicines.
Fifteen years in development by Carmat, a company based in Paris, the heart has been approved for clinical trials at cardiac surgery centers in Belgium, Poland, Saudi Arabia and Slovenia.
In France, where the device is not yet cleared for human implantation, regulators have requested more animal tests; those tests are continuing.
This is the first artificial heart to use cow-derived materials - specifically, tissue from the pericardial sac that surrounds the heart. Biological tissue has been used in mechanical blood pumps only in valves, Dr. Rogers said.
When the natural heart is partly damaged or diseased, patients might keep it and have a mechanical aid implanted to bolster blood flow. Such pumps - especially those that aid the left side of the heart - are in wide use both as a bridge to a transplant and for lifetime therapy.
A totally artificial heart for extended use would be of great value, but it's far too early to know if the Carmat heart, as yet untried in humans, will be that device.
The cost of the Carmat heart would be about $200,000, said Dr. Piet Jansen, medical director at Carmat. He did not expect it to be brought to market in Europe before the end of 2014. Once the company gains momentum with its clinical studies, he said, it plans to start working through the regulatory process in the United States.
The Carmat heart has two chambers, each divided by a membrane. That membrane has cow tissue on one side - the side that is in contact with blood - and polyurethane on the other side, which touches the miniaturized pumping system of motors and hydraulic fluids that changes the membrane's shape. (The motion of the membrane pushes the blood out to the body.) The embedded electronics and software adjust the rate of blood flow. Patients can wear the batteries under the arm in a holster, or in a belt, among other options.
Cow tissue is also used for the heart's artificial valves, which were created by Dr. Alain Carpentier, a cardiac surgeon and a pioneer of heart valve repair who is also a founder of Carmat. The cow tissue is chemically treated so that it is sterile and biologically inert.
The device is regulated by sensors, software and microelectronics. And its power will come from two external, wearable lithium-ion batteries.
The heart's design and development relied heavily on aerospace testing strategies by EADS, the European Aeronautic Defense and Space Company, one of Carmat's backers, Dr. Jansen said.
Dr. Jansen said that one design requirement for the heart was that it last five years. The company has been doing bench tests to see whether it can last that long.
Dr. Lynne Warner Stevenson, director of the cardiomyopathy and heart-failure program at Brigham and Women's Hospital in Boston, is optimistic about the new device.
"I applaud the pioneers who developed it," she said, "and the patients and families who will go down this path for the first time."
The New York Times
(China Daily 07/28/2013 page11)