Relationship between left ventricular vortex and preejectional flow velocity during isovolumic contraction studied by using vector flow mapping.

OBJECTIVES: The purpose of this study was to investigate the relationship between the vortex in left ventricle (LV) during the isovolumic contraction (IVC) period and the preejectional flow velocity in LV outflow tract (VLVOT ).

METHODS: Color Doppler loops were acquired for vector flow mapping in apical long-axis view in 76 patients with dilated cardiomyopathy, 61 patients with coronary artery disease and 36 healthy controls.

RESULTS: All normals exhibited an IVC vortex reaching the LV base. VLVOT was significantly related to IVC vortex area flux, transmitral A velocity, mitral annular a' velocity and E/e' ratio, respectively. Transmitral A velocity was the only independent predictor of VLVOT (R2  = 0.292, P = 0.001). In patients the IVC vortex could reach the LV base, middle, or apex. VLVOT was significantly related to range, area and area flux of the IVC vortex, LV size, LVEF, mitral annular velocities, E/e' ratio, transmitral A velocity, and IVC time, respectively. Range and corrected area flux of the IVC vortex, LV end-systolic short diameter, and IVC time were independent predictors of VLVOT (R2  = 0.608, P < 0.001).

CONCLUSIONS: In normals, the transmitral A velocity (momentum) is efficiently transferred from mitral orifice to LV outflow tract by a normally formed IVC vortex, and transmitral A velocity is the only independent predictor of VLVOT . However, in patients with a wide range of LV enlargement and dysfunction, the momentum transfer is associated with not only the LV dimension and function, but also the range and volume of the IVC vortex.