Wednesday, June 07, 2006

Defibrillation's Alternative

A new approach would stop ventricular fibrillation before it started.

By Duncan Graham-Rowe

Treating a failing heart by zapping it with a painful, powerful electrical shock has become the standard procedure. Now, a medical device company, based in West Henrietta, NY, has patented a technique that avoids the need for such dramatic treatment, by predicting the onset of fibrillation -- the heart rhythm that can lead to sudden death -- and treating it before it occurs.

The preventative treatment does, like defibrillation, involve electrically stimulating the heart, says Michael Weiner, CEO of Biophan Technologies. But this new technique's weak signal would be minuscule compared to the jolt that defibrillators normally deliver. "I know patients with defibrillators who live in fear of that son-of-a-gun going off," he says.

According to Weiner, the algorithms underpinning the technology could easily be programmed into new implantable cardioverter-defibrillators (ICDs). More importantly, because the technique uses only a fraction of the power needed for defibrillation, it could also be incorporated into pacemakers -- much smaller and cheaper devices normally used only to stop the heart rate from slowing by regulating it with regular low-power electrical pulses, compared with the one-off, high-powered shocks used by defibrillators to correct fast or erratic rhythms.

Ventricular fibrillation (VF, also known as "V fib")) occurs when the cells in the two lower chambers of the heart, the ventricles, stop beating in synchrony, causing them to start quivering. This can prevent the heart from pumping blood properly and, if untreated, can lead to death, usually within a few minutes.

Defibrillators attempt to resynchronize the cells by electrically shocking them, either through electrode paddles applied externally to the skin or through conducting leads that sit inside the heart, connected to an ICD. However, although ICDs have been effective in treating fibrillation, the experience is extremely unpleasant. "It's like dropping a bowling ball on someone's chest from a height of two meters," says Mark Spano, a "chaotician" who has made several studies of fibrillation at the Naval Surface Warfare Center in Silver Spring, MD.

Biophan's algorithms build on chaos theory, which has been used previously to highlight the early signs of VF. This earlier research suggested that by detecting changes in the nonlinear or chaotic signals within an EKG, it's possible to sense the first signs of VF. Then by applying a controlled but noisy or chaotic signal back into the heart, a normal rhythm can be regained and VF avoided altogether.

So far, the company has patented only the algorithms, which is the way cardiac companies work, says Weiner. Now that the patents have been issued, Biophan is seeking collaborators from the industry to put the theory into practice.