Mechanism of mitral regurgitation in hypertrophic obstructive cardiomyopathy

Abstract

Echocardiography of the mitral valve in patients with hypertrophic obstructive cardiomyopathy has revealed an abnormal pattern of movement. The abnormality is characteristic, readily recognized, and can be explained in anatomical and physiological terms. It consists of a sharp reopening of the valve during systole when it should normally remain in the fully closed position. This abnormal movement mirrors the mid-systolic onset of both outflow tract obstruction and mitral regurgitation. It was only absent in the two patients with the disease in whom both mitral regurgitation and outflow tract obstruction were also absent. A second and less striking abnormality was a reduced diastolic closure similar to that seen in mitral stenosis and attributed to slow left ventricular filling. The echo from the septum is also unduly prominent.

The 50-Year History, Controversy, and Clinical Implications of Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy

“…Although a general consensus began to emerge that true obstruction occurred in patients with HCM and operative intervention (with ventricular septal myectomy or myotomy) was a valid strategy by which severe heart failure-related symptoms could be relieved by abolition of the outflow gradient (4,46,47,49 -51), investigators at Hammersmith Hospital (London) continued to be highly vocal opponents of obstruction and critics of myectomy surgery until only very recently, persisting in the view that outflow gradients were simply incidental to the clinical disease process (9,31,33).…”

Role of Noninvasive Imaging Modalities to Better Understand the Mechanism of Left Ventricular Outflow Tract Obstruction and Tailored Lesion-Specific Treatment Options

“…Moreover, the demonstration of systolic anterior motion (SAM) of the mitral valve leaflets resulting in systolic contact with an hypertrophied septum as a main mechanism of LVOTO ( Figure 1) provides a solid platform for fundamental understanding of HCM with a wide clinical spectrum. [9][10][11][12] This finding has provided a scientific rationale and background to the surgical removal of the hypertrophied septum to relieve LVOTO. 13, 14 In addition to an initial operative mortality between 5% and 8%, the failure rate between 10% and 20% to relieve symptoms after myectomy 15 tempered initial enthusiasm for this surgical approach.…”

Systolic Anterior Motion of the Mitral Valve with and without Asymmetric Septal Hypertrophy

“…The presence of SAM in IHSS has been correlated with the presence of hemodynamically significant LVOT obstruction and it has also been utilized in the assessment of medical and surgical therapy of IHSS (12,26,32,33). However, SAM may not always be associated with LVOT obstruction in IHSS (15).…”