Effect of concomitant asymmetric septal hypertrophy when assessing the severity of aortic valve stenosis: an in-vitro study.

Background And Aim Of The Study: Aortic valve stenosis (AS) is an important cardiovascular disease that affects between 2% and 7% of the elderly population in industrialized countries. AS often coexists with asymmetric septal hypertrophy (ASH), which is generally caused by a protrusion of the hypertrophied left ventricular outflow tract (LVOT) just below the aortic valve. The study aim was to determine, based on measurement of the aortic valve effective orifice area (EOA), if ASH might potentially interfere with the assessment of AS severity.

Methods: The effects of different levels of ASH (from normal to 90%) on the EOA measured from orifices mimicking different AS severities, and from a home-built AS model constructed from a bioprosthetic aortic valve, were examined in a pulsatile flow in-vitro model.

Results: For the most severe AS, the level of ASH had no impact on the measured EOA. In contrast, for the less severe AS, beyond an ASH level of 50% the AS severity was progressively overestimated, and reached a reduction of about 60% of EOA for a ASH level of 90%.

Conclusion: The presence of concomitant ASH may cause an overestimation of the hemodynamic severity of AS. The extent of overestimation is more important in less-severe AS. Hence, the presence of ASH may lead the clinician to conclude, erroneously, that the AS is severe and that aortic valve replacement is indicated. However, beyond an ASH level of 50% the AS severity can be accurately determined.