Early diastolic overinflation in diastolic mitral regurgitation.

An 81-year-old man presented with exertional dyspnea at our hospital. An electrocardiogram was recorded, which showed 2:1 atrioventricular (AV) block. Transthoracic 2-dimensional echocardiography showed that the left ventricular (LV) wall thickness and wall motion were normal. Color Doppler echocardiography showed no significant valvular heart disease. Pulsed Doppler echocardiography at the mitral valve showed a high early diastolic inflow (E) wave (111 cm/s) with a short deceleration time (125 ms) and diastolic mitral regurgitation (MR) in early diastole (Fig. 1, right panel, arrow). By raising the baseline to reveal the full profile of the diastolic regurgitant flow, pulsed Doppler echocardiography showed that the pressure gradient at the mitral cusp was 8.3 mmHg (Fig. 1, left panel, arrow). There have been reports about the mechanisms of diastolic MR. As coaptation of the mitral valve is not isolated to the tips but, rather, is the result of the overlap of several millimeters of tissue, LV contraction is necessary for definite mitral valve closure. Thus, AV block of any degree may become a cause of diastolic MR [1]. The reversed AV pressure gradient during atrial relaxation may also contribute to this. Without AV block, diastolic MR may be present in a high LV diastolic pressure setting, such as that during aortic regurgitation [2]. In the present case, a longitudinal global strain from speckle tracking showed that the left ventricle was already dilated to the level of end-diastole (Fig. 2, dotted line, arrow). This suggests that LV early diastolic pressure might be as high as end-diastolic pressure. Along with the decrease in left atrial pressure after atrial contraction, there might be a reversed pressure gradient between the left ventricle and the left atrium. The global strain decreased during mid-diastole, suggesting gradual decrease in LV size due to diastolic MR (Fig. 2). Thus, global strain was useful in estimating the LV volume change during diastole in this patient.