Conduction system in systemic lupus erythematosus with atrioventricular block.

We describe the clinical course and the postmortem cardiac findings in a 12 year old girl with systemic lupus erythematosus, complete heart block, renal failure and hyperkalemia. The conduction system was examined by serial section. The sinoatrial and atrioventricular nodes were found to be almost completely replaced by granulation tissue; we believe that this finding is related to the systemic lupus. The hyperkalemia is not considered to be the cause of the block, since the block persisted despite the lowering of the blood potassium level and the morphologic findings in this case are not found in hyperkalemia.