por Lynn Shapiro
, Writer | April 01, 2009
The minimally invasive technique "clearly has a very big advantage: being able to insert a valve without opening up the chest, in a beating heart, without the use of heart/lung bypass," Dr. Makkar says.
Explaining the workings of the valve, Dr. Makkar says that the Edwards SAPIEN valve is a frame; mounted inside the frame is a tissue valve that is crimped on a balloon. "You take this balloon, thread it through the artery in the groin and work your way into the heart. We position this valve at the site of the old valve and blow up the balloon, which pushes the old valve out to the side and the new valve instantly takes over all functioning."
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Dr. Makkar adds that those patients who are too frail for this approach, called the femoral approach, can be treated with a balloon that is inserted through the chest. This is called the transapical approach. Edwards has a transapical valve that goes through the bottom (apex) of the heart and then is deployed.
"As time goes by, catheter-based implants will be used on a widespread basis," Dr. Makkar says. "And the technique may have cost advantages. The fact that patients heal faster means hospital stays are shortened." (The technique is performed as a partnership by an interventional cardiologist and heart surgeon.)
Bench-testing for Product Lifespan
At present, Dr. Makkar's team is bench-testing the valves to see how long they'll last. One of the major determinants of lifespan is how the leaflets--the doorways that push blood out of the heart but prevent regurgitation--are processed and repaired.
"The hope is that they would last as long as tissue valves. The metal and plastic valves last forever but you need to take a blood thinner if you're using a metal valve," he says.
Dr. Makkar estimates there about 750,000 people in the U.S. who suffer from aortic stenosis and says that 2 percent to 4 percent of Americans older than 65 have some degree of this disease. Only severe cases need to be replaced, Dr. Makkar says. There are about 25,000 Americans who fit into the "severe" category. This population is due to increase, as millions of boomers reach 65 every year.
Read more about SAPIEN and watch a video:
*A Note of Correction: A previous version of this report incorrectly stated that the non-surgical portion of the PARTNER trial has just begun. In fact, both arms of the trial, surgical and non-surgical, have been underway since 2007. In device trials patients receive therapy as they are enrolled, unlike drug trials in which the entire cohort of subjects is enrolled and then treated.Back to HCB News