Anatomy, histology, and pathology of the cardiac conduction system: Part II

Various pathologic conditions producing atrioventricular block are reviewed. Calcific atrioventricular block (aortic stenosis, mitral valve annular calcium), active infective endocarditis ("ring" abscess), acute and healed myocarditis, various collagen-vascular diseases, amyloidosis, and tumors are reviewed as causes of atrioventricular block. Various diseases producing bundle-branch block are also discussed.