MAGNETIC-RESONANCE VELOCITY MAPPING OF NORMAL HUMAN TRANSMITRAL VELOCITY PROFILES

We used magnetic resonance imaging (MRI) velocity mapping to assess the velocity profile of early diastolic mitral inflow in 11 normal subjects, Velocity maps of left ventricular inflow were obtained in the horizontal long axis of the left ventricle at the time of peak early diastolic filling. Velocity profile curves across the mitral inflow were obtained at 1-cm intervals from the mitral ring to 4 cm into the cavity. The jet width was 3.06 +/- 0.64 cm at the mitral ring level, increasing to 3.6 +/- 0.61 cm at 4 cm. The peak/mean velocity was 1.2 +/- 0.07 at the mitral ring and increased to around 1.4 at 3-4 cm from the mitral ring. The point at which the peak velocity was recorded at each level was skewed towards the septal side by 10%-13% of jet width from the center at the mitral ring and 2-4 cm from the ring. However, at a depth of 1 cm, corresponding to the mitral tip level, the peak velocity was at the center of the jet. The ratio of vertical and horizontal dimensions of the jet cross section was 1.11 +/- 0.05. Thus, the mitral inflow velocity profile is relatively flat at the mitral ring and tip level; the inflow jet cross section is effectively circular.