A degenerative lesion of the approach to the atrioventricular node producing second-degree and third-degree atrioventricular block.

We report a case of a degenerative approach lesion in an 83-year-old male with diabetes mellitus, hypertension, and ischemic heart disease. His ECGs changed from first-degree atrioventricular (AV) block 14 years ago, to third-degree AV (A-H) block. A pacemaker was implanted for bradycardia. He died 4 years later from heart and renal failure. Serial sections through the conduction system revealed total depletion and fatty replacement of the atrial muscle at the approaches to the AV node.