Arrhythmias, Cardiac [Disease/Finding] Heart Block [Disease/Finding] M0009945 C3038 233916004 1023276 Heart Block N0000001430 C0018794 Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects. Heart Block D006327