What is a biventricular pacemaker (bi-V pacemaker)?

When you have heart failure, your heart is weakened and doesn’t pump as well as it should. A cardiac resynchronization therapy (CRT) device may help your heart work better. CRT is also called “biventricular pacing.” For many heart failure patients, a CRT device can reduce symptoms and improve their quality of life. Most biventricular pacemaker CRT devices also incorporate the extra technology and features of an implanted cardioverter defibrillator (ICD) as well. This is called a “biventricular ICD” or “CRT-ICD.”

Your heart has an electrical system that controls its pumping action (called the “conduction system”). This system sends automatic electrical impulses through the heart muscle that tell the heart to beat properly. If you have heart failure, the heart muscle may be damaged, and these electrical signals may travel more slowly through this damaged muscle. This is referred to as a “conduction system delay,” which is also known as a “bundle branch block.” This abnormality can easily be detected on an electrocardiogram (ECG), which is a simple recording of your heart rhythm. About one-third of patients with a cardiomyopathy have a bundle branch block.

If you have a bundle branch block on your ECG, this may mean that the heart’s pumping chambers (ventricles) may not be synchronized properly and may not be contracting together. If this happens, the heart becomes less efficient and less blood is pumped out to the body, which can make heart failure worse.

If your left and right ventricles are not contracting together and you have heart failure, a CRT device ensures that the contractions are timed correctly. Then, the two pumping chambers become resynchronized, and blood is pumped out of the heart more efficiently. Whereas a standard pacemaker or ICD contains only one or two wires (“leads”) on the right side of the heart, a CRT device uses a third wire. This extra wire sends signals to the left side of the heart, so that the electrical impulses can stimulate both right and left ventricles simultaneously, thereby increasing the pumping force of the heartbeat.

Like an ICD, a CRT device is implanted by a cardiac electrophysiologist, who is a heart doctor that specializes in the electrical disturbances of the heart.