Key result
Patients with systolic anterior motion (SAM) alone had narrower LVOT measurements and greater ejection fractions compared to patients with ASH alone.
Why the study?
Dynamic left ventricular outflow obstruction can occur in the absence of echocardiographic asymmetric septal hypertrophy, but its characteristics and mechanisms are not well defined.
Observational (n=10)
Dynamic left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve can occur in the absence of asymmetric septal hypertrophy, driven by a narrow LVOT and abnormal ejection dynamics.
Answers are grounded in this paper and cite their sources.
SAM without ASH may occur with normal septal parameters; leaves open whether ASH is required for IHSS diagnosis.
Asymmetric septal hypertrophy (ASH) is considered the unifying link in the spectrum of hypertrophic cardiomyopathies. ASH and mitral valve systolic anterior motion (SAM) are the two most important echocardiographic criteria for the diagnosis of idiopathic hypertrophic subaortic stenosis (IHSS). Ten patients found have SAM without ASH were studied. Septal thickness, thickening, and excursion were normal. Seven patients had left ventricular ejection times (LVET) measured before and after amyl nitrite inhalation. In six of them, corrected LVET increased by more than 40 msec. Four patients underwent diagnostic cardiac catheterization. Resting or provocable left ventricular outflow tract (LVOT) gradients were demonstrable in all four patients. The echocardiographic features in patients with SAM alone, ASH and SAM, and ASH alone were compared. compared. LVOT measurements in patients with SAM alone (2.2 +/- .4 cm) and ASH and SAM (2.1 +/- .5 cm) were similar and narrower than in patients with ASH alone (2.8 +/- .5 cm, P less than 0.001). Ejection fractions in patients with SAM alone (79 +/- 10%) were greater than in patients with ASH and SAM (66 +/- 16%, P less than 0.02) or ASH alone (60 +/- 15%, P less than 0.001). Thus, dynamic left ventricular outflow obstruction can exist in the absence of echocardiographic ASH. LVOT width and abnormal LV ejection dynamics may contribute to the LVOT obstruction with or without the presence of ASH.
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Mintz et al. (1978) conducted an observational in Systolic anterior motion of the mitral valve (n=10). Systolic anterior motion (SAM) without asymmetric septal hypertrophy (ASH) vs. ASH alone or ASH with SAM was evaluated on Left ventricular outflow tract (LVOT) measurements (p=<0.001). Patients with systolic anterior motion (SAM) alone had narrower LVOT measurements and greater ejection fractions compared to patients with ASH alone.
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