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Definition of Bundle Branch Block
The bundle branches focus and intensify the pacing signals that originate in the sinoatrial (sa) node, concentrating them enough to stimulate and synchronize the powerful contractions the ventricles need to eject blood from the heart. Various factors can block this electrical pathway.
Among the most common are coronary artery disease (cad), valvular heart disease, heart failure, and cardiomyopathy. These conditions result in abnormal blood supply to the myocardial cells, interfering with their normal functions. Bundle branch block also can exist without an identifiable cause in people who have no apparent heart disease.
Bundle Branch Block and ECG (EKG)
Bundle branch block typically shows up on an electrocardiogram (ecg) though often does not cause symptoms. The heart continues to contract and pump blood normally (unless other heart disease interferes) because factors other than electrical stimulation contribute to heart function. However, the slowed, delayed, or interrupted flow of the electrical pacing impulse can cause a slow heart rate (bradycardia) or other types of arrhythmia.
The location of the blockage can disrupt the synchronized contractions of the ventricles, causing one to contract before the other instead of both contracting simultaneously. Often, the bundle branch block requires only regular monitoring, not treatment. The location and extent of the block determines the approach. When the block is fairly extensive, a pacemaker may be necessary to regulate the heart’s electrical activity.
Bundle branch block that coexists with other forms of heart disease may require careful coordination of therapeutic measures to preserve overall cardiac function to the greatest extent possible.
See also SICK SINUS SYNDROME.