Diseases characterized by pathological irregularities in the HEART CONDUCTION SYSTEM. They may be associated with other heart diseases and syndromes (e.g., BRUGADA SYNDROME; NEUROMUSCULAR DISEASE, HEART BLOCKS), isolated or may result from injuries. You can have a conduction disorder without having an arrhythmia, but some arrhythmias arise from conduction disorders. OMIM: 601144.