心エコー・ドップラー法による僧帽弁輪石灰化に伴う弁輪狭窄の重症度評価

Recently, mitral annular calcification (MAC) is a common finding with increasing of elderly orrenal failure patients. Mitral stenosis secondary to MAC is not rarely observed. Pressure halftime method by continuous wave Doppler echocardiography is often used to evaluate the severityof the stenotic mitral valve due to MAC. But, the method for calculating correct mitral orifice areais not established. We performed transthoracic Doppler echocardiography and cardiac catheterizationin 15 patients with rheumatic mital stenosis and 10 with mitral stenosis due to MAC, and calculatedthe severity of the mitral stenosis by pressure half time (PHT), continuity equation methods andGorlin formula. Pulsed tissue Doppler imaging methods were used for evaluating left ventricular(LV) early diastolic wall motion velocities. Results were as follows. 1) The mitral orifice areas determinedby PHT method were lower than those by continuity equation methods or Gorlin formulain patients with mitral stenosis due to MAC, and significant correlation was observed in rheumaticmital stenosis between the mitral orifice areas obtained by PHT and continuity equation methods,but not in mitral stenosis due to MAC. 2) The peak early diastolic LV myocardial velocities alonglong and short axes decreased significantly in mitral stenosis due to MAC than those in rheumaticmital stenosis. In conclusion, as mitral orfice area determined from PHT method is strongly influencedby early diastolic LV dysfunction in mitral stenosis due to MAC, continuity equation methodshould be recommended.