Decellularized Heart Valve Gets Market Go Ahead From FDA

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Main Category: Cardiovascular / Cardiology
Also Included In: Medical Devices;  Pediatrics / Children's Health
Article Date: 08 Feb 2008 - 9:00 PDT

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The US Food and Drug Administration (FDA) has given the go ahead for the first decellularized human heart valve to go on the market in the US.

A decellularized heart valve is a replacement heart valve made from donated human tissue with all trace of the donor's cells removed.

The traditional method for making a replacement heart valve is to remove it from a deceased donor heart, inspect, clean and decontaminate it so it does not introduce infection into the recipient. This is called an allograft product because it is a human as opposed to an animal heart valve, although the donor and recipient invariably have different genes.

Doctors would rather repair than replace heart valves where there is a choice, because this leaves patients with their own tissue which is more likely to resist infection and less likely to need blood thinners. However, in some cases, such as congenital heart problems, or where calcium deposits or rheumatism have damaged the valves, replacement is the only option.

Heart surgeons prefer to use allograft heart valves for children because they don't calcify as quickly and thus reduce the prolonged need for blood thinners, unlike valves from pigs and cows.

CryoLife Inc, based in Kennesaw, Georgia, who make the decellularized heart valve, take the traditional heart valve making process one step further, they remove the cells and cellular debris from the valve, leaving only the "scaffolding", the connective tissue. The decellularized heart valve still works like a heart valve, except the absence of donor cells and cellular traces means the recipient's immune system is less likely to attack it and trigger rejection.

Director of FDA's Center for Devices and Radiological Health, Dr Daniel Schultz said:

Today's clearance is a promising advance in allograft products." He said the FDA welcomed manufacturing innovations that gave patients more treatment options.

This particular CryoLife decellularized heart valve, which the FDA called the SynerGraft valve, is designed to replace the pulmonary heart valve, either as part of another surgical procedure, or because the original becomes diseased, doesn't work properly, or stops working altogether. The pulmonary valve makes blood flow from the heart's right ventricle to the lungs.

An example of where the new valve is used in conjunction with another procedure is in the reconstruction of the outflow tract of the right ventricle, which is commonly performed in children who are born with a defect in this part of the heart.

Another example is the Ross procedure, where a patient's defective aortic valve is removed, replaced with his or her own pulmonary valve, and the SynerGraft valve (which Cryolife call the CryoValve SG) is implanted in place of the re-located pulmonary valve.

The FDA gave the go ahead for CryoLife to market the SynerGraft after reviewing the clinical results of SynerGraft valve implants that took place between 2000 and 2004. These results compared the clinical results of 342 SynerGraft implants with 1,246 traditional allograft valve implants.

After comparing death rates, and events such as operations that had to be done again, deterioration of valve structure, inflammation of the inner lining of the heart (endocarditis), and blood clots for the two valve groups, the FDA concluded that the decellularized valves performed at least as well as the traditional ones.

President and CEO of Cryolife, Steven G Anderson said:

"CryoValve SG may offer an attractive valve replacement option for many children born with heart defects." He said the new valve could also be a:

"Good option for patients who have undergone valve replacement surgery as young children, but may require another valve replacement as they've grown into adulthood."

Welcoming the news, Professor of Cardiothoracic Surgery at the Indiana University School of Medicine, Indianapolis, Dr John W Brown, said that as a heart surgeon he was "very excited" to be able to offer children born with heart defects, who often face "frequent and challenging surgeries" this "great opportunity to live active, normal lives".

The FDA have asked CryoLife to continue to study the new valve after it is launched on the market, and collect evidence of its long term benefits and risks.

More specifically, the FDA has asked for the company to monitor: long-term safety and hemodynamic function, immune response, and explant analysis.

CryoLife said it believed this evidence will help to find out if the SynerGraft process reduces the likelihood and strength of immune system rejection in the recipient, and if the recipient's own cells start to grow in the new valve.

Click here to find out more about heart valve surgery (Mayo Clinic).

Sources: FDA News, Cryolife press statement, Mayo Clinic website.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
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