Dr. Nitika Dabas, MD, MPH

Just as with a standard pacemaker, a biventricular pacemaker consists of a small battery pack and electrical leads, or small wires that conduct electricity to the heart. CRT pacemakers have two or three leads, placed in the upper and lower chambers of the heart. The device measures the contractions of the heart, and if the heart begins to beat out of time it will send small, rhythmic pulses of electricity to resynchronize (hence the name 'cardiac resynchronization therapy) the contractions. This allows the heart to pump blood to the rest of the body more efficiently. Sometimes a CRT is combined with a different kind of device called an implantable cardioverter-defibrillator or ICD, which uses a higher burst of energy to restart the heart if it stops suddenly.

When a biventricular pacemaker is inserted, the wire leads are usually placed via a small incision near the shoulder, then threaded through a vein to the heart. The battery pack is placed under the skin of the chest near the collarbone. Once everything is in place, the leads are connected to the battery, and the CRT can begin helping the heart beat correctly.

It is normal to experience swelling and discomfort as the incisions from surgery heal. It takes time for the heart to adjust to the pacemaker, so vigorous activity should be kept to a minimum for the first few weeks. Strong magnetic fields may affect how the CRT functions, so patients may be advised to avoid them. As patients heart begins to pump blood more effectively, they should soon begin to feel stronger and less fatigued.

Placement of an ICD is similar to the placement of a standard pacemaker. An incision is made near the shoulder, and two insulated wires or leads are threaded through a vein and placed in the heart. The battery pack, a small metal device, is inserted beneath the skin of the chest just under the collarbone. Once everything is in place, the wires are connected to the battery, and the ICD is functional.

Patients may have swelling and discomfort after surgery as their incisions heal.The heart needs several weeks to adjust to the ICD, so it is best for them to avoid strenuous activity at first. Strong magnetic fields may affect the function of the ICD, so doctors tell patients to avoid certain activities, such as having an MRI or even keeping their cell phones too close to their ICD. Within a few weeks patients' hearts should be beating more safely and effectively.

To implant the device, a long, flexible tube, called a catheter, is inserted into a large vein in the groin and advanced to the heart. Once the tube reaches the left side of the heart, X-ray is used to guide a thinner catheter into the left atrial appendage. The tiny device is then passed through the tube and into the appendage. When the doctor has made sure it is in the right place, she takes the catheter out, and the procedure is completed.

This minimally invasive procedure usually requires a hospital stay of at least one day. Normal activities may be resumed within a few days. About 45 days following implantation, a test will be done to determine whether the device has closed the left atrial appendage. Check-ups have to be performed every year to make sure the device is in place.