Adevice that's being touted as "breakthrough" technology for the treatment of heart failure is being trialed by UAB researchers in a national clinical study sponsored by the device manufacturer, Impulse Dynamics of Orangeburg, N.Y. Scientists will investigate the effects of the Optimizer III™ System in patients with moderate to severe heart failure to see if the treatment improves quality of life and exercise tolerance.
Congestive heart failure affects more than 5 million Americans and can be caused by damage to the heart muscle from injuries such as heart attacks, untreated coronary artery disease or persistent high blood pressure. It can also result from genetic or molecular abnormalities or infections. Symptoms of heart failure begin to appear as the heart becomes progressively too weak to pump enough blood to meet the energy needs of the body.
The new implantable device is similar in size and shape to an artificial heart pacemaker, but that's where the likeness ends. A pacemaker makes sure the heartbeat doesn't go too slowly by initiating contractions when there's a missed beat. The Optimizer, however, senses when a beat has already started and sends an electrical signal to strengthen the heart's contraction.
The Optimizer uses a new method called cardiac contractility modulation (CCM) to change how cells use calcium to strengthen heart muscle contractions in patients suffering from heart failure. Because calcium provides energy to the cell, higher calcium improves cell function making the whole cell stronger and thus strengthening every heart beat. "The heart is a muscle, and just like all other muscles in the body it needs electrolytes," said UAB's principal investigator and cardiologist Dr. Jose A. Tallaj. "When the heart contracts, it releases calcium from specialized cisterns inside the cells, causing the cell to contract. As the calcium is pumped back into the specialized cisterns inside the cell, the heart relaxes."
Conventional pacemakers use "excitatory" electrical signals to regulate the heartbeat, but the Optimizer delivers "non-excitatory" electrical impulses that modify heart cell function while the heart is not pacing. Leads from the device are placed on the surface of the septum in the right ventricle and deliver an electrical signal during the "absolute refractory period" and are intended to enhance contractility and overall cardiac performance. "We hope to improve patients' symptoms so they have less shortness of breath while bathing, for instance, and can get strong enough to make a trip to the store, improving their quality of life," Tallaj said.
Doctors currently try to strengthen the heart mobility using drug therapy called inotropes, but Tallaj said they only use such therapy in patients with end-stage heart disease because of the side effects. Drug therapy has been shown to stiffen the heart, increase heart arrhythmia and cause sudden death and cell fatigue. "These side effects can be detrimental in the long run, so we hope the Optimizer will allow us to offer the same treatment without the side effects," Tallaj said.
UAB is the center conducting the study in Alabama and is evaluating acceptable patients over 18 with an ejection fraction of 35 percent or less or who suffer from class III or IV congestive heart failure on appropriate medical therapy. The length of the study depends on outcomes, but he expects the trial to be open for at least one year. Tallaj said they have implanted one device so far in their randomized study in which patients will receive either the implantable device or current standard drug therapy. Investigators will be comparing objective, functional and quality-of-life measures and hoping for improvements in all of these areas, Tallaj said.
Tallaj is optimistic about the Optimizer device based on the promising results of preliminary animal studies. "If the results of this trial are as positive as what we've seen in the animal studies, I think this will be the next big thing in heart failure treatment," he said. He added that while they expect patients to have a marked improvement in their quality of life as a result of this device, he is hoping for more. "Historically, patients who feel better and are able to do more have an improved survival, and that may be the case with this device. But for now, we're happy if we can just offer these patients a better life."
