Physicians at CardioVascular Associates are using a new pacemaker that offers hope to patients with congestive heart failure, a condition where the heart is unable to pump enough blood to meet the rest of the body's needs.
Cardiac resynchronization therapy is a new treatment for heart failure that uses an implantable device to improve the pumping efficiency of the heart. In healthy people, the four chambers of the heart contract in a synchronized manner to move blood through the body. However, in many patients who have heart failure, the electrical impulses that coordinate the contractions of the heart's chambers are impaired. As a result, in up to 50 percent of people who have advanced heart failure, the two lower chambers, called ventricles, no longer contract at the same time. This may worsen the symptoms of heart failure, which include shortness of breath, fatigue and swelling of the feet and ankles.
In cardiac resynchronization therapy, a pacemaker is implanted in the upper chest to resynchronize the heart's contractions by sending tiny electrical impulses to the heart muscle. This can help the heart pump blood throughout the body more efficiently and reduce the symptoms of heart failure, making the condition easier to treat with standard drug therapy and dietary/lifestyle changes.
"Standard pacemakers are used to treat rhythm disturbances in the heart, which is a different condition. This pacemaker uses a pulse generator that is implanted in the chest and connected to the heart by three wires - or leads - that deliver electrical impulses. One wire is placed in the upper right heart chamber and the others are placed in each of the two lower chambers, where they simultaneously stimulate both the left and right ventricles, in effect resynchronizing them," explains Dr. Russell Reeves of CardioVascular Associates. "The new InSync pacemaker doesn't cure heart failure but it can improve the patient's health to a point where other therapies, such as Beta blockers and ACE Inhibitors, are much more effective."
Nearly 5 million Americans are afflicted with congestive heart failure which is often a result of other cardiovascular diseases. Each year, more than 500,000 new cases of heart failure are diagnosed in the United States. Risk of heart failure, which is the most costly cardiovascular disease in the US, increases dramatically with age.
Symptoms often associated with heart failure are fatigue, dyspnea (shortness of breath) and edema (swelling, usually of the feet and ankles). Even with mild to moderate disease, heart failure patients have less energy, lower fitness levels and more physical complaints.
The most common cause of heart failure in the US is blockage in the arteries that supply blood to the heart muscle. The main pumping chamber, the left ventricle, frequently enlarges in this condition. In addition, the electrical activation of this chamber frequently becomes abnormal. The combination of an enlarged pumping chamber and slow electrical activation makes the heart pump less efficiently. The electrical activity may be conducted to one side of the heart chamber, causing it to contract before the other side. The electrical activity spreads slowly from one side of the heart to the other, so that one part of the heart muscle is contracting while the other part is beginning to relax. This leads to an "internal sloshing" and inefficient pumping.
Cardiac resynchronization, also called biventricular pacing, places a pacemaker wire or "lead" on opposite sides of the pumping chamber. This makes the chambers contract in unison and thus more efficiently. Studies have shown that this improves the ability of patients to exercise and improves their quality of life. It is not considered a cure for congestive heart failure because it does not treat the underlying problems, but it frequently does allow for more effective medical treatment. Patients that would benefit from such a procedure are those with an enlarged main pumping chamber and slow conduction from one side of the heart to the other, usually referred to as a left bundle branch block pattern. Cardiac resynchronization is different from the normal use of a pacemaker, which is to prevent episodes of slow heart rhythm or conduct the electrical impulse from the upper chamber to the lower chamber.