New Dual Action Device Keeps Heartbeats in Sync
By Marge Dwyer
Beth Israel Deaconess Medical Center Correspondent
Ask Beth Israel Deaconess Medical Center cardiologist Dr. Charles Haffajee to discuss the latest technology for managing hearts that beat too fast or slow and one patient in particular comes to mind. The man’s case reflects many of the advancements that have occurred in the field of cardiology over the last three decades.
First there was the bad heart attack in the 1970s that left the middle-aged Massachusetts man with a rapid heartbeat that eventually placed him among the first Americans to undergo cutting-edge ventricular tachycardia open heart surgery. Then in the 1980s he developed heart block (where the heart is very slow) and atrial fibrillation, a condition in which the beat of two upper heart chambers (the atria) are out of sync with that of the heart’s two lower chambers (the ventricles).
To control the irregular heartbeat, shortness of breath and other symptoms, a pacemaker was implanted. About the size of a 50-cent piece, the battery-operated device was surgically placed under the skin of the upper chest. Pacemakers are usually used to treat a slow heartbeat (bradycardia), or a resting heart rate of below 60 beats per minute. A wire (or lead) from the pacemaker is attached to the right side of the heart and carries electrical signals to speed up the heart when it slows down.
By the late 1980s, the patient needed an additional device – an implanted cardioverter defibrillator. Developed in the 1980s, the small battery-powered device sends shocks through the veins to the heart if an irregular beat is detected or if the heart stops (cardiac arrest), literally jump-starting the person back to life.
Despite these procedures, by the late 1990s the patient was experiencing severe heart failure. In this condition affecting 6 million Americans, the walls of the right and left ventricles do not contract at the same time and the weak heart fails to pump properly. “Three or four times each year the patient had to go to the hospital to have excess fluid drained from his abdomen,” Dr Haffajee says.
Luckily, French doctors conceptualized and developed in the late 1990s a pacemaker that allowed pacing of both lower chambers, the weakened left ventricle and the right ventricle. Called a biventricular pacemaker (BiVP), the device is among the newest devices on the market today for treating advanced heart failure. This then was combined with the defibrillator.
The patient had the BiVP-defibrillator implanted a few years ago. “Except for one instance, in which left ventricle’s wire moved and had to be re-positioned, you are likely to find this Massachusetts man on the golf course and experiencing far fewer symptoms of heart failure. For over four years he has not been admitted to the hospital for congestive heart failure,” says Dr. Haffejee, a specialist in electrophysiology, who has overseen the man’s heart care for the past 25 years.
“While the pacemaker has been around about 40 years and has become more user-friendly over the years, BiVP first became available in the U.S. about five years ago. They just now are catching on and are being increasingly used,” he says.
The development, also called cardiac resynchronization therapy, couldn’t come at a better time. With America’s aging population, demand for the device is likely to increase. About 300,000 to 400,000 new cases of heart failure are diagnosed each year in the nation. Millions more have irregular heartbeats due to normal aging of the heart or from damage to heart muscles caused by a heart attack, virus or genetic conditions. Some medications can affect the heart rate as well, requiring intervention.
How does a biventricular pacemaker work? The small surgically inserted battery-powered device has two or three wires that go through a vein in the right and left ventricles via veins. The doctor programs the device to release electrical impulses that stimulate both chambers of the heart to pump together and function more effectively.
“With traditional pacemakers, you get regular beats only on the right side and the left side of the heart is one-fifth of a second behind the other side, so they are out of sync,” Dr. Haffajee says. “By having a BiV pacemaker working the two sides of the heart at the same time, people are living longer, having fewer hospitalizations for heart failure, their quality of life is improved, and there is less chance of cardiac arrest (when the heart stops due to an electrical impulse problem).”
What’s more, about 95 percent of patients can have the BiVP device connected through the veins without opening the chest, he says. “This is important because people needing these devices often are very sick and so doctors want to minimize the possibility of complications and post operative pain.”
Two large international clinical trials conducted by device makers over the last few years have shown promising results. The COMPANION trial, sponsored by Guidant (now Boston Scientific), followed more than 1,500 heart failure patients from 128 U.S. medical centers. Medtronic’s Multicenter InSync Randomized Clinical Evaluation (MIRACLE) ICD study evaluated the efficacy of the device in 420 patients with heart failure in 45 centers in the United States.
The studies found 70 percent of patients who receive the BiVP device and medications felt better and their heart function improved. The remaining 30 percent who did not show improvement have led Dr. Haffajee, director of device trials and director of electrophysical outreach programs for Beth Israel Deaconess Medical Center, to continue to study ways to refine the technology. “We want to find a way to identify in advance those people who won’t respond and to do things differently to improve their odds of responding,” he says. He and his colleagues are looking at the timing between the upper and lower chambers, where best to pace in the weakened left ventricle and whether a change in the timing between the lower chambers would help.
Another major application of the BiVP technology is as a “bridge” for a heart transplant — to keep a patient alive until a heart becomes available for transplant, he adds. With this technology, patients often can wait two to three years until a heart becomes available. “Some patients have improved so much while on the device that they’ve been able to come off the list for a transplant,” he says.
To schedule a consultation with the experts at the CardioVascular Institute at Beth Israel Deaconess Medical Center, call (617) 667-5356.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted January 2009
