Background:

Left ventricular (LV) stroke volume (SV) is ejected by a combination of longitudinal shortening (LS), circumferential shortening (CS) and ventricular twist. Longitudinal shortening is caused by the motion of the mitral annulus towards the apex, causing wall thickening (CS and radial thickening), reduction of the ventricular cavity and LV ejection. The role of LS in aortic stenosis (AS) is not defined.

Objective:

The aim of this study was to analyze the contribution of LS and CS to SV and left ventricular ejection fraction (LVEF) in severe AS.

Methods:

The study included 152 patients (70 ± 12 years, 64 women) with severe AS (valve area <1 cm2) studied by cardiac Doppler echocardiography. The contribution of LS to SV was evaluated by considering the base of the heart as a cylinder, with volume = base x height; the base was assumed as a circle with radius equal to (systolic septal thickness + systolic posterior wall thickness + end-systolic diameter)/2; and height, as an average of the mitral lateral, septal, anterior and inferior annulus systolic excursion. The contribution of CS to SV was estimated as: SV - contribution of LS to SV. Both contributions were expressed in absolute form and as SV percentages (%SV-LS and %SV-CS).

Results:

Longitudinal shortening contributed with approximately 2 thirds of SV (68 ± 18 %) and CS with the rest. SV-LS correlated inversely with SV (r = - 0.45 p <0.001) and SV-CS had direct correlation (r = 0.45 p <0.001). The contribution of %SV-LS was greater in patients with LVEF <50%. Percent SV-LS correlated inversely with relative wall thickness (RWT) (r = 0.32, p <0.01).

Conclusion:

The contribution of LS to SV is greater than that of CS, and correlates inversely with SV. Percent SV-LS is higher in patients with EF <50%. The aforementioned findings could have implications when considering cut-off points for longitudinal function indices (strain) without considering LVEF and/or ventricular geometry.