Defibrillation’s Alternative
A new approach would stop ventricular fibrillation before it started.
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.
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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.
Weiner is confident that the approach will work because there’s enough published research from the academic community to support it. In particular, Biophan’s patents build on work carried out by Spano and William Ditto, previously at Georgia Institute of Technology, now in the University of Florida’s Department of Biomedical Engineering in Gainesville.
In the 1990s, Spano and Ditto carried out work on animals and some limited tests on humans to demonstrate that some types of fibrillation can be corrected using low-power signals. This work is grounded in chaos control theory, says Spano. “It’s not much more complicated than a kid taking a baseball bat and balancing it vertically in the palm of their hand,” he says. But instead of nudging a bat, one is applying electrical signals to nudge the heart back into a healthy rhythm. “Once you get the heart back to a regular beat, it tends to revert and maintain a normal rhythm,” he says.
“There’s every reason to believe it would work,” says Ditto. And every reason to try: “A quarter of all deaths are ultimately due to ventricular fibrillation.”
Others are equally optimistic. Since evidence exists that early signs of epileptic attacks can be detected, it’s conceivable that similar early warning signs of fibrillation can be detected, says Andrew Grace, a consulting cardiologist at Papworth Hospital in Cambridge, England, and a research fellow at the University of Cambridge.
The catch is that it can be difficult to test predictive algorithms because, despite its role in many deaths, VF is quite a rare event, he says. “You can induce it, but then you are not allowing the natural conditions to occur.” Even so, the potential benefits to patients are great enough that the prospect of pre-empting VR should be encouraged, even though it’s difficult to test, says Grace. This is especially compelling since about one-third of shocks delivered by defibrillators turn out to come from false alarms.
If they can get the energy levels down to those of a pacemaker, it will dramatically change the way lives are saved, says Ditto. “It takes more energy to start a heart than it takes to start a car on a cold day,” he says. This reality makes defibrillators large, short-lived, and expensive.
