Two alternatives to heart surgery, the Edwards and the CoreValve heart valves, offer a less invasive alternative to surgery but do so is very different ways.

The Edwards unit is bigger and is deployed when a heart specialist blows up a balloon to position it. The Corevalve heart valve expands into its original shape, giving structure to the the valve.

Specialists claim that the Edwards unit is more durable yet the Corvevalve unit is easier to use. The ease of use can costly though; many patients have had to recieve pace makers to restore the heart's rhythm. Concerns about the durability of the Corvevalve, which is made of a nickel and titanium alloy -- in contrast to the steel Edwards unit -- are also on the surface.

"For its part, the Edwards device also encountered problems during its development. In 2005, the company stopped an early study after several patients died. The company then revised the implant procedure."

To read the full article, including a nunmber of comments from doctors and physicians worldwide, click here: http://www.nytimes.com/2009/10/01/business/01valveside.html?scp=9&sq=October+1+2009&st=nyt