Persistent atrial standstill developed in a patient with rheumatic heart disease: electrophysiological and histological study.

A case with persistent atrial standstill is presented which developed from atrial fibrillation associated with rheumatic combined valvular heart disease. In addition to clinical and electrocardiographic findings, electrophysiological and histological studies by using microelectrode technique and electron microscopy, respectively, were carried out on specimens from the right atrial appendage resected at mitral valve surgery. Scattered but severe loss of myocardial cells in the atria and deterioration of the action potential of these poorly sustained myocardial cells were confirmed. The suggestive evidence is also shown that the deteriorated action potential observed by micro-electrode technique in this case may be composed of calcium current.