Q: Will you please explain a left branch block and what it implies? Other than occasional fatigue, I feel no ill effects.
A: The heart has a conduction system that is like a major wiring system along which the electrical impulses travel from the top right side (sinus node in the right atrium) where they are formed, to the bottom chambers (ventricles) to coordinate the contraction of each heartbeat (see picture). Slowing or blocking of the impulse produces changes that can be recorded in the ECG. A person may or may not experience symptoms from such alterations in conduction. When the impulse slows or blocks in the right ventricle, it is called right bundle branch block, and in the left ventricle, left bundle branch block. The changes may or may not be important and need to be correlated with your clinical condition by your cardiologist. In general, left bundle branch blocks carry more significance than right bundle branch blocks, but this needs to be determined by your doctor.