intraventricular block, altered conduction of the cardiac impulse within the ventricles. The block can occur as a right bundle branch block, left bundle branch block, hemiblock, left anterior or posterior fascicular block, or bifascicular block. Intraventricular blocks are identified on an electrocardiogram when the QRS duration is greater than normal. They can be caused by coronary artery disease, valvular heart disease, ventricular hypertrophy and fibrosis, cardiomyopathy, or degeneration of the conduction system. Prognosis is based on the underlying cardiac condition. Also called sinoatrial (SA) block. See also bundle branch block, heart block, hemiblock, intraatrial block.
