Dynamics of the Left Ventricular Outflow Tract during the Cardiac Cycle Assessed (with) Via Tridimensional Echocardiography

Abstract

Objective: To analyze the left ventricular outflow tract (LVOT) dynamic during cardiac cycle with 3D Echocardiography (3DEcho). Material and Methods:We prospectively included 58 patients sent to our lab for a transesophageal echocardiographic study (TEE). All TEE were done with a 3DEcho probe, obtaining gated images (4 beats, complete volume) for off-line analysis. The cardiac cycle was divided in proto (S1), mid (S2) and telesystole (S3); and proto (D1), mid (D2) and telediastole (D3). The LVOT area was measured by planimetric method in short axis, orthogonal to the long axis of the LVOT in each phase.Results: Mean age was 69.7±15 years, 60% male. LVOT area (cm 2 ) in each phases was: S1: 4,36±1,02; S2: 4.08±0,94; S3: 3,82±0,93; D1: 3,59±0,98; D2: 3,77±1,01; D3: 4,15±1,11. Maximal area was observed in S1, corresponding to the closing position of the anterior leaflet of the mitral valve (ALM) and a few excursion of the interventricular septum (IVS) to the LVOT; minimum area was obtained in D1 coinciding with some persistence of IVS in the LVOT and maximal opening position of ALM. The total modification of the area was 17±12% (p<0.0001), changing also the shape of the LVOT from a partially elliptical or circular one (systole) to an markedly elliptical or semilunar (diastole).Conclusion: the LVOT has a variation in area and shape during cardiac cycle, depending basically of the movement of IVS (systole) and mitral valve opening (diastole).