A biventricular pacemaker, sometimes referred to as a biventricular heart pacemaker or cardiac resynchronization therapy, is an artificial device that is implanted in the body to help the heart function properly. More specifically, it helps regulate the heart rate, and make sure that the right atrium and right ventricle, as well as the left ventricle and right ventricle cooperate properly. It is this last role — stimulation of the right and left ventricles — that sets a biventricular pacemaker apart from a traditional pacemaker. Biventricular pacemakers are quite small — about the size of a pocket watch or even smaller.
A healthy human heart sends out electrical signals in order to maintain a proper rhythm. The electrical signals are sent to the ventricles — two of the heart's four chambers. The ventricles then squeeze or contract in a synchronized fashion to expel blood and oxygen from the heart and to the rest of the body. When the ventricles get out of synch, less blood is pumped to the rest of the body than is required. In a patient with heart failure, this becomes an issue because the heart is already in a weakened state.
The goal of the biventricular pacemaker is to place the heart back into the proper rhythm and facilitate the synchronized contraction of the ventricles. As a result, the proper amount of oxygen and blood are expelled to the body and heart failure symptoms may improve. For this reason, the biventricular pacemaker is often referred to as cardiac resynchronization therapy (CRT).
When implanted, three tiny wires, called leads, are inserted under the skin of the chest and are connected to the heart. Synchronization of the heart is the goal, wherein the atrium and ventricle pace together. The wires stimulate a heartbeat so that if an irregular heart rhythm occurs, the biventricular pacemaker will attempt to pace the rhythm to a more regular one. If this fails, a shock to the heart may occur.
Sometimes a doctor may recommend a biventricular pacemaker in conjunction with an internal defibrillator, or internal cardiac defibrillator (ICD). If the heart is not pumping well with each beat, as determined by ejection fraction measurement, the ICD is responsible for shocking the heart back into a normal rhythm. Coupled with a biventricular pacemaker, a patient with heart failure can lead a much more comfortable lifestyle.
Cardiologists, or cardiac surgeons, will generally recommend and/or perform this procedure, which can take anywhere from two to three hours to perform. Patients are usually kept overnight for observation and monitoring. Postoperatively, patients will receive a temporary identification card with biventricular pacemaker information on it. Within a few months, the pacemaker manufacturer sends a permanent card. This is useful if the patient requires medical attention.
Along with regular checkups by the physician or cardiologist, and since pacemakers run on batteries, a battery functionality assessment will usually be performed. When the pacemaker’s battery is low, it will need to be replaced. Pacemakers generally last about four to eight years, but if they're coupled with an ICD, they generally last about two to four years.