Biventricular pacemaker: Cardiac resynchronization therapy for heart failure

If you have heart failure, you could be a candidate for a biventricular pacemaker — an implanted device that can resynchronize your heart chambers and help your heart pump more effectively.

You have heart failure and your doctor says you need a biventricular pacemaker. You may be thinking, "Bi-ven-tricky what?" But don't fear the complicated-sounding name, a biventricular pacemaker is a symptom-improving device that stimulates or "paces" both of your heart's lower chambers (ventricles) to help your heart pump more efficiently and improve your quality of life.

Biventricular pacemaker's function

A biventricular pacemaker doesn't increase heart rate, but rather helps coordinate the pumping action of the heart by sending electrical signals to both of your ventricles.

Normally the left and right ventricles beat in a coordinated fashion — efficiently pumping blood out to the body. Damage to the heart muscle, often caused by certain types of heart failure, can distort this timing — called ventricular dyssynchrony. Regular pacemakers pulse only the right ventricle. A biventricular pacemaker paces both ventricles so that all or most of the ventricular muscles "squeeze," or "pump," together. This allows your heart to pump blood more effectively and can dramatically improve heart failure symptoms. Because this treatment resets the ventricles' pumping mechanism, it's also referred to as cardiac resynchronization therapy (CRT).

Who needs a biventricular pacemaker?

Not everyone who has heart failure needs a biventricular pacemaker. If you have moderate to severe heart failure, certain conduction problems, or your heart failure symptoms persist despite the use of medications, you may be a candidate for a biventricular pacemaker.

How does a biventricular pacemaker work?

A biventricular pacemaker works much like a traditional pacemaker and consists of two parts.

Main pacemaker components

Pulse generator. This small metal container houses a battery and the electrical circuitry that regulates the rate of electrical pulses sent to your heart.
Leads. These flexible, insulated wires deliver the electrical pulses to your heart.

In most other types of pacemakers, only two leads are attached to your heart — one to the right atrium and one to the right ventricle. With a biventricular pacemaker, a third lead is placed in the lower left chamber (left ventricle). This connection to both of your ventricles allows the pacemaker to sense when they're beating out of sync. The biventricular pacemaker then attempts to synchronize the left ventricle with the right so that they squeeze at the same time (resynchronization).

A biventricular pacemaker with a defibrillator

People who are at risk of sudden death or life-threatening arrhythmias may need a biventricular pacemaker combined with an implantable cardioverter-defibrillator (ICD). The unit can sense when your heart beats abnormally and activates the defibrillator to deliver calibrated electrical shocks to restore your normal heartbeat.

What's implantation surgery like?

The surgery to implant a biventricular pacemaker can be performed with local anesthetics and a sedative that puts you in a relaxed state but allows you to remain aware of your surroundings. The procedure typically lasts two to three hours.

During implantation, a shallow cut is made in your upper chest and the pacemaker's leads are inserted through a puncture into a vein. The doctor then guides the leads through the vein and positions them inside your heart using X-ray images to guide the placement. Next the doctor creates a pocket under the skin just beneath your collarbone to hold the pulse generator.

After implantation surgery

The hospital stay for biventricular pacemaker implantation is one to three days. Before you leave, your pacemaker is programmed to ensure it's working effectively. A return visit is scheduled to refine the settings.

You will periodically need your biventricular pacemaker checked via telephone. You'll connect to a phone line with either a transmitter attached to wristbands on each of your arms or a wand placed over your pacemaker. These devices send pacemaker information to your doctor's office. A technician on the other end of the line checks your heart rate and rhythm and assesses your pacemaker's function and remaining battery life.

If your biventricular pacemaker has a defibrillating function, you'll need regular office visits to check the equipment.

Like other pacemakers, a biventricular pacemaker must have its pulse generator replaced in four to seven years, when its battery begins to show signs of wearing out. How long the battery will last depends on many factors, such as how often it's used and how much energy is required to pace the heart. Typically, only the pulse generator is replaced, not the leads.

How will you know it's working?

You won't feel your biventricular pacemaker while it's working. However, if your pacemaker includes a defibrillator, you may feel some discomfort if and when it kicks in to correct a life-threatening arrhythmia. Depending on how strong a shock is needed to reset your heart rhythm, you may feel anything from a light flutter to a stronger thump in your chest to a shock that can knock you to the ground. Discomfort lasts only a second or two, though, and ultimately may be saving your life.

You should notice an improvement in your heart failure symptoms shortly after your biventricular pacemaker is implanted. Perhaps you'll notice you're able to walk longer without tiring out. It may, however, take a month or more for you to notice marked improvement.

Special precautions

Biventricular pacemaker malfunction due to interference from electronics and security systems is rare. Still, take these precautions:

Cellular phones. It's safe to talk on a cell phone, but avoid placing your cell phone directly over your pacemaker implantation site when the phone is turned on. Although unlikely, your pacemaker could misinterpret the cell phone signal as a heartbeat and cause the pacemaker or defibrillator to function inappropriately.
Security systems. Passing through an airport metal detector won't interfere with your pacemaker, although the metal in it may sound the alarm. Avoid lingering near or leaning against a metal-detection or anti-theft system. To avoid potential problems, carry an ID card stating that you have a pacemaker. This should be supplied to you after your implantation procedure.
Medical equipment. If your doctor is considering any medical procedure that involves intensive exposure to electromagnetic energy, tell him or her that you have a pacemaker. Such procedures include magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) scans, therapeutic radiation for cancer treatment, and shock wave lithotripsy, which uses shock waves to break up large kidney stones or gallstones. If you're having surgery, the electrocautery procedure that controls bleeding also can interfere with pacemaker function.
Power-generating equipment. Some high-voltage equipment may potentially interfere with your pacemaker or defibrillator. Be careful around welding equipment or very large engines. If you work around this equipment or similar equipment, tell your doctor so that he or she can figure out the best course of management.

Devices that present little or no risk to pacemaker function include microwave ovens, televisions and remote controls, radios, toasters, electric blankets, electric shavers, and electric drills.

Biventricular pacemakers have become a valuable tool in treating heart failure. Cardiac resynchronization therapy through the use of a biventricular pacemaker has proved to significantly improve quality of life and long-term outcomes for many people with heart failure that doesn't respond to the usual drug therapy.