Mechanisms, features, and significance of diastolic mitral regurgitation: a case series

Abstract

Background Diastolic mitral regurgitation (DMR) is a type of functional mitral regurgitation. Its occurrence in the diastolic phase of cardiac cycle renders DMR an easily ignored entity. Confusing it with systolic mitral regurgitation occasionally happens. The reversal of left atrioventricular pressure gradient during diastole and the incomplete closure of mitral valve are the essential conditions for DMR. Diastolic mitral regurgitation develops under various situations, where the mechanisms of diastolic reversal of left atrioventricular pressure gradient differ. Case summary Patient 1 was a 50-year-old man diagnosed with 2:1 second-degree atrioventricular block (AVB). Patient 2 was a 70-year-old man diagnosed with first-degree AVB. Patient 3 was a 66-year-old man diagnosed with atrial fibrillation with long intermission and occasional atrial flutter with unequal conduction. Patient 4 was a 54-year-old woman diagnosed with dilated cardiomyopathy with complete left bundle branch block. Patient 5 was a 36-year-old man diagnosed with severe acute aortic regurgitation secondary to subacute bacterial endocarditis. Discussion Although the degree of DMR is relatively mild, its appearance generally prompts further clinical considerations. The appreciation of DMR has an incremental value for diagnosing and evaluating the underlying cardiovascular disease.

Heart rate‐dependent mitral regurgitation

“…Mitral regurgitation is a common valvular disease, which is usually observed during ventricular systole when blood is being ejected through the aortic valve and its backflow from the left ventricle to the left atrium cannot be prevented by the mitral valve. In addition to the more frequently observed systolic mitral regurgitation, cases of diastolic mitral regurgitation have been described, which are usually due to atrioventricular block, severe aortic regurgitation, or dilated cardiomyopathy 4,5 . The underlying mechanism for the insufficiency of the mitral valve in the presented case was not the absence of atrioventricular synchrony, but rather the prolonged left ventricular filling time as a result of extreme bradycardia, and thus, mitral regurgitation was observed during systole.…”

“…In addition to the more frequently observed systolic mitral regurgitation, cases of diastolic mitral regurgitation have been described, which are usually due to atrioventricular block, severe aortic regurgitation, or dilated cardiomyopathy. 4,5 The underlying mechanism for the insufficiency of the mitral valve in the presented case was not the absence of atrioventricular synchrony, but rather the prolonged left ventricular filling time as a result of extreme bradycardia, and thus, mitral regurgitation was observed during systole. However, considering the patient had left bundle branch block, ventricular dyssynchrony, as opposed to atrioventricular dyssynchrony, prior to pacemaker implantation is very likely.…”

Left ventricular haemodynamic effects in a patient with endocarditis

“…When the LVEDP rises above the atrial pressure, the mitral valve leaflets approach each other. This results in incomplete mitral valve closure and end-diastolic MR before the LV contracts [1]. The diastolic regurgitant volume is usually small due to a low ventricle-atrial pressure gradient, with a far lower flow velocity than systolic MR [1,2].…”

“…This results in incomplete mitral valve closure and end-diastolic MR before the LV contracts [1]. The diastolic regurgitant volume is usually small due to a low ventricle-atrial pressure gradient, with a far lower flow velocity than systolic MR [1,2]. It is important to recognise diastolic MR in patients with aortic regurgitation since it implies a severe haemodynamic state that requires emergency surgery.…”

Time overlap of mitral and aortic regurgitations in a patient with systolic heart failure

“…MR lasts for the whole systole and early diastole, whereas AR for the entire diastole and early systole ( AR is presumed to end with diastole while MR with systole [1][2][3]. However, in patients with severe systolic HF, MR and AR may last exceed the duration of their respective periods [4,5].…”