Diastolic Mitral Regurgitation

Case Report

A 90-year-old female patient was admitted with congestive heart failure. The ECG showed a heart rate of 40 beats per minute with Mobitz II second-degree atrioventricular (AV) 2:1 block (Figure 1). Two-dimensional echocardiography revealed concentric left ventricular (LV) hypertrophy with normal systolic function (LV ejection fraction 70%) and dilatation of the left atrium. Doppler echocardiography detected only minimal early systolic and moderate to severe diastolic mitral regurgitation (Figure 2), mild-to-moderate, particularly diastolic tricuspid regurgitation, and elevated pulmonary artery pressure. Subsequently a VDD pacemaker was implanted and transthoracic echocardiography was repeated with a normal AV conduction time. Doppler echocardiography showed only minimal early systolic mitral regurgitation without diastolic regurgitation (Figure 3) and only minimal tricuspid regurgita-tion. Although clinical signs of congestive heart failure had already improved after initiation of medical therapy, they disappeared only after implantation of the pacemaker.

Diastolic mitral and tricuspid regurgitation is a common finding in AV conduction abnormalities [1]. Delayed ventricular contraction following atrial contraction may lead to diastolic mitral and tricuspid regurgitation, because AV valve closure does not occur unless ventricular systole supervenes [2]. In the event of higher ventricular than atrial pressure during atrial relaxation, an incompletely closedAV valve may lead to a reverse gradient with a considerable regurgitation volume. Sequential dual-chamber pacing at a physiological AV interval improves haemodynamics by prolongation of the LV diastolic filling time and elimination of diastolic mitral regurgitation, thus lowering LV filling pressures and increasing cardiac output [3].

Diastolic mitral regurgitation in the presence of normal LV function can contribute to overt congestive heart failure if a high reverse ventriculo-atrial pressure gradient occurs. In this case, sequential AV pacing at a physiological conduction time may bring substantial improvements in haemodynamics by elimination of diastolic mitral regurgitation.