Roentgen video densitometer study of mitral valve closure during atrial fibrillation.

Abstract

Roentgen video densitometer analysis of video angiograms has demonstrated that during electronically induced atrial fibrillation, the mitral valve in nonthoraconotomized dogs can be closed as effectively by ventricular contraction alone as during cardiac driving with a normal sequence of atrial and ventricular contraction. The major role of atrial contraction on ventricular function in the normal heart would appear to be limited to its effect on end-diastolic ventricular filling. In the failing heart in which the vigor of ventricular contraction is depressed, the evidence suggests that suitably timed atrial contraction and relaxation enhance the efficiency of atrioventricular valve closure.