An echocardiographic study of the fluid machanics of obstruction in hypertrophic cardiomyopathy

Abstract

Just before mitral-septal contact, the protruding leaflets project at high angles relative to flow. At these high angles, flow drag, the pushing force of flow, is the dominant hydrodynamic force on the protruding leaflet and appears to be the immediate cause of obstruction. The high angle between flow direction and the protruding leaflet precludes significant Venturi effects. Even earlier in systole, at leaflet coaptation, flow drag is dominant in half of the patients, with angles relative to flow > 15 degrees. After obstruction is triggered, it appears from our data and model that the leaflet is forced against the septum by the pressure difference across the orifice. The increasing acceleration of Doppler flow is explained by a time-dependent amplifying feedback loop in which the rising pressure difference across the orifice leads to a smaller orifice and a higher pressure difference.

Sustained Improvement After Combined Anterior Mitral Leaflet Extension and Myectomy in Hypertrophic Obstructive Cardiomyopathy

“…The Venturi mechanism and flow drag of the leaflets due to increased mitral leaflet length, laxity, and anterior displacement of the papillary muscles allow the valve to protrude in the outflow tract. 4 Also, inward displacement of the papillary muscles toward each other results in chordal slack in the central leaflet portion and consequently SAM in the central portion of the valve. 5 To counteract these forces, the pericardial patch is grafted in the center portion of the anterior leaflet, where SAM typically reaches a maximum.…”

“…The most commonly performed intervention is surgical myectomy according to the technique developed by Morrow et al 2 Hypertrophic cardiomyopathy, however, frequently presents with several anatomic alterations of the mitral valve apparatus, including increased mitral leaflet area (MLA), length, and laxity, as well as anterior displacement of the papillary muscles. [3][4][5][6][7][8][9][10][11][12] These structural abnormalities, which are not corrected after a successful myectomy, may predispose to residual SAM and result in a suboptimal outcome with persistence of outflow obstruction and mitral regurgitation. [13][14][15] We therefore performed anterior mitral leaflet extension (MLE), one of several repair techniques originally developed by Carpentier, 16 in combination with myectomy in patients with HOCM and an enlargement of the anterior mitral leaflet.…”

Hipovolemia grave como causa de insuficiência mitral aguda

“…We postulate that the functional impairment of the mitral valve was due to the increased outflow tract velocities, which affected leaflet coaptation [4][5][6] . Increased left ventricular systolic pressure causing an increased transvalvular gradient may also have contributed to the degree of mitral regurgitation.…”

Intraoperative Imaging in Aortic Valve Surgery as a Safety Net

“…SAM may develop following aortic valve replacement and necessitates additional mitral valve replacement. The mechanism of SAM has been reported as being due to a Venturi effect or drag effect (Cape et al, 1989;Sherrid et al, 1993Sherrid et al, , 2003. There are several risk factors for developing SAM in mitral valve repair, including a short distance between the coaptation point and interventricular septum (C-Sept), a large angle between the mitral and aortic annular plane, an decreased length ratio of the anterior and posterior mitral leaflets, excess valvular tissue, and a hyperkinetic left ventricle (Maslow et al, 1999).…”