Background: Dynamic LV outflow tract (OT) systolic pressure gradient (SPG) and dysfunction of the mitral valve (MV) are classical features of hypertrophic obstructive cardiomyopathy (HOCM). The physiological substantiation of the SPG and mitral regurgitation origion in HOCM is insufficient. The present study exemines if LV OT obstruction and mitral regurgitation in HOCM can be conditioned by LV activation asynchrony caused by LV excitation sequence disturbances. Methods: 55 consequtive HOCM pts (mean age 31.7±3.2 yrs) were evaluated by M-mode, two dimentional and Doppler echocardiography with SPG determination, mitral regurgitation assesment, and short distance (h, cm) between interventricular septum (IVS) and MV anterior leaflet in systole measurement; by cardiac catheterization with direct LV OT SPG measurement and by LV endocardial mapping in relation to His potential registered in the AV node region. We compared the LV apex (LVA) His-V interval with the same for the hypertrophied part of IVS and calculated the difference in ms(t) between the His-V LVA and the His-VLV OT. The the “–“ sign before the t index showing the LV apex delay as compared to its OT activation. Results: The linear regression analyses revealed: 1) negative relations between h (distance between IVS and anterior MV leaflet in systole and SPG on LVOT (r=-0, 4, p<0, 001), 2) negative relation between the t index and SPG magnitude (r=-0.32, p<0.001), and 3) positive relation between t and h, (r =0.3, p =0.001). Conclusion:The LV outflow tract systolic pressure gradient and mitral regurgitation in HOCM are conditioned by the LV activation asynchrony caused by LV apex and papillary muscles activation delay relatively to the hypertrophied part of IVS.
Xanya Sofra Weiss
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