Implantable defibrillators are devices that can prevent sudden cardiac death in patients with ventricular tachycardia (VT), a potentially life-threatening fast heart rhythm that originates in one of the ventricles of the heart, by delivering a shock to terminate the abnormal rhythm.
While most patients tolerate these devices very well, the shocks are unpredictable, and for some people, even a few of them can be psychologically devastating. This uncertainty may cause tremendous anxiety that limits a patient’s quality of life.
Doctors often start medical therapy once a shock occurs, but this does not always prevent future shocks. For some of those patients, radiofrequency catheter ablation is needed to eliminate the short circuits causing the abnormal rhythm.
However, in patients with weak hearts, “the ablation procedure itself can be quite taxing,” says Pramod Bonde, M.D., assistant professor of surgery. “In fact, there are a lot of patients who are turned down for this procedure because of their poor heart function.” To give such patients an option, in October, Yale physicians successfully performed what they believe were Connecticut’s first ablations for VT using a new hybrid technique that takes advantage of an extracorporeal membrane oxygenation (ECMO) machine, which provides temporary support of heart and lung function for patients whose weak hearts would have otherwise made the ablation procedure extremely risky.
“With ECMO, patients with weak hearts become candidates for VT ablation. This is important for those who must endure repeated shocks from their defibrillators as a result,” says Bonde, director of Yale’s ECMO program, who performed the procedures alongside electrophysiologist Joseph G. Akar, M.D., Ph.D., associate professor of medicine and director of the Cardiac Electrophysiology Laboratory. “We can maximize their chances of survival and chances of success with this new technique.”
The first patient treated at Yale with the procedure was a man with a weak heart and so-called “VT storm,” characterized by incessant life-threatening heart rhythms that trigger multiple repetitive defibrillator shocks. The patient, who had already had two open-heart operations, had been receiving as many as six shocks in less than one minute from his defibrillator, and Akar wanted to perform a radiofrequency catheter ablation to pinpoint the source of the problem and treat it.
The physicians performed what they say is typically a 4- to 6-hour procedure with a team of about 15 people, including surgeons, electrophysiologists, nurses, perfusionists, technologists and others—a procedure that patients with weak hearts can tolerate with ECMO.
Akar was pleased that the ECMO support allowed him to take the time he needed to perform the ablation procedure carefully. Most importantly, he says, ECMO support allowed him to induce the dangerous heart rhythm long enough for him to locate its source.
“The VT procedure is potentially long and technically complicated,” Akar says. “Many patients have such severe underlying heart disease that they would really be unable to withstand the stress of this procedure if it was not for the hemodynamic support provided by the ECMO.”
Bonde says the development of Yale’s adult ECMO program in the past year—at first as a temporary measure for patients with adult respiratory distress syndrome, acute heart failures, catheter-lab emergencies and other serious events—laid the foundation for the successful hybrid ablation procedures.
“We’ve matured the adult ECMO program and are having very good outcomes, and these procedures are an extension of that,” he says. “We waited until now to do it because we wanted to make sure the team is confident and that complex procedures such as VT ablation can be supported with ease.”
Other centers in the country have offered the hybrid procedure, either with ECMO or with pumps that take over the function of the heart, but not the lungs. “This is the first such case at Yale and to my knowledge in Connecticut,” Akar says. “I look forward to offering this important therapy as we build our ECMO and VT programs to treat challenging cases.”
The two doctors predict Yale will treat at least 20 to 30 patients next year with the hybrid procedure, and more as patients and referring physicians learn the procedure is available.