Gauging risks of sudden death

Richard Cohen started with goals similar to Kamm’s but with a focus on a specific group: people at risk for sudden cardiac death.

This condition claims the lives of 300,000 Americans yearly. Almost all die of arrhythmias–problems with the heart’s pacing machinery. An especially lethal arrhythmia is the one called ventricular fibrillation. The condition, which makes the heart’s all-important left ventricle vibrate rapidly, is often fatal.

An implantable defibrillator, which shocks an errant heart back onto a healthy beating timetable, can head off sudden cardiac death. But using these devices costs up to $80,000 a patient. “So the real question is, how do you decide who needs a defibrillator?” says Cohen, an HST faculty member.

Electrophysiological testing works, but the procedure–which requires introducing a catheter into the heart–is costly and inconvenient. Cohen has devised a non-invasive alternative based on tracking a tiny wrinkle in the heart rhythm.

This phenomenon, known as T-wave alternans, involves changes in the heartbeat from one beat to the next. Early studies found it in arrhythmia patients at serious risk of dying from a future pacing breakdown, but not in similar patients with more hopeful prospects.

Since the rhythm change is measured in millionths of a volt, though, it’s far too small to show up on conventional heart tests. “You’re not likely to see it on an electrocardiogram no matter how hard you look,” he says.

But Cohen’s group created a computer-based system that lets them tease out this signal from the many others that can cause ups and downs on an electrocardiogram. The technology has been licensed to a company Cohen helped found, and the firm is seeking federal approval to use it in predicting serious arrhythmia risks.

“I’d like to see it tried in patients with congestive heart failure,” Cohen says. “They’re at risk for sudden cardiac death, and it would be good to know if this system can help them.”

Meanwhile, Cohen has moved on to other challenges. One is to create a non-invasive test that would offer detailed 3-D depictions of the heart, pinpointing what heart-muscle regions are losing blood because of arterial blockages.

“Our goal is an inexpensive test physicians could use in their offices,” says Cohen. “We think it could someday replace the conventional exercise stress test.”

by Richard Anthony « Previous | Next »

On Topic: health science+technology