Characters of anatomy and flow dynamics of left ventricular outflow obstruction by echocardiography

Objective To observe the characters of anatomy and flow dynamics of left ventricular outflow obstruction(LVOTO) by echocardiography. Methods Echocardiographic date were analyzed in 159 patients with LVOTO.The thickness of the basal interventricular septum(IVST-b) and left ventricular posterior wall(LVPWT), the peak gradient of LVOT were measured. Systolic anterior motion of mitral valve( "SAM" ) and the spectral profile in LVOT were recorded by continuous wave Doppler. Results One hundred and fifty-nine patients were divided into four groups: group A (hypertrophic obstructive cardiomyopathy, 69 cases), group B (hypertensive left ventricular hypertrophy, 60 cases), group C (senile thickening of the basal of interventricular septum, 19 cases) and group D (discrete subaortic membrane, 11 cases). IVST-b, IVST-b/ LVPWT and the peak gradient of flow in group A were significantly increased than those in group B and C (P<0.01). There was significant correlation between IVST-b, IVST-b/ LVPWT and the peak gradient of flow(r=0.56, 0.61, respectively, P<0.01) in group A+ B+ C. The CW character of LVOTO in group A, B and C was like the shape of "Dagger" , however, "approximately equilateral triangle" in group D. Conclusions The charicteristic spectral profile in LVOT can be used to differentiate pure mechanical obstruction from the dynamic obstruction or combined obstruction; IVST-b and SAM are the two important anatomical morphology factors in determination of the degree of dynamic obstruction. Key words: Echocardiography; Left ventricular outflow obstruction; Hemodynamics