Early systolic flow impacting the posterior surfaces of the mitral valve leaflets was observed in 95% of obstructive HCM patients vs 22% of nonobstructive and 11% of normal patients (P<0.001).
Observational (n=82)
Does echocardiographic vector flow mapping identify the hydrodynamic cause of early systolic anterior motion of the mitral valve in obstructive hypertrophic cardiomyopathy?
Vector flow mapping demonstrates that early systolic flow impacting the posterior surfaces of protruding mitral valve leaflets initiates systolic anterior motion in obstructive hypertrophic cardiomyopathy.
p-value: p=<0.001
BACKGROUND: The hydrodynamic cause of systolic anterior motion of the mitral valve (SAM) is unresolved. OBJECTIVES: This study hypothesized that echocardiographic vector flow mapping, a new echocardiographic technique, would provide insights into the cause of early SAM in obstructive hypertrophic cardiomyopathy (HCM). METHODS: We analyzed the spatial relationship of left ventricular (LV) flow and the mitral valve leaflets (MVL) on 3-chamber vector flow mapping frames, and performed mitral valve measurements on 2-dimensional frames in patients with obstructive and nonobstructive HCM and in normal patients. RESULTS: We compared 82 patients (22 obstructive HCM, 23 nonobstructive HCM, and 37 normal) by measuring 164 LV pre- and post-SAM velocity vector flow maps, 82 maximum isovolumic vortices, and 328 2-dimensional frames. We observed color flow and velocity vector flow posterior to the MVL impacting them in the early systolic frames of 95% of obstructive HCM, 22% of nonobstructive HCM, and 11% of normal patients (p 60° of local vector flow onto the posterior surface of the leaflets whether the flow was ejection (59%) or the early systolic isovolumic vortex (41%). Ricochet of vector flow, rebounding off the leaflet into the cul-de-sac, was noted in 82% of the obstructed HCM, 9% of nonobstructive HCM, and none (0%) of the control patients (p < 0.001). Flow velocities in the LV outflow tract on the pre-SAM frame 1 and 2 mm from the tip of the anterior leaflet were low: 39 and 43 cm/s, respectively. CONCLUSIONS: Early systolic flow impacts the posterior surfaces of protruding MVL initiating SAM in obstructive HCM.
Ro et al. (Sat,) conducted a observational in Obstructive hypertrophic cardiomyopathy (n=82). Obstructive hypertrophic cardiomyopathy vs. Nonobstructive HCM and normal patients was evaluated on Color flow and velocity vector flow posterior to the mitral valve leaflets impacting them in early systolic frames (p=<0.001). Early systolic flow impacting the posterior surfaces of the mitral valve leaflets was observed in 95% of obstructive HCM patients vs 22% of nonobstructive and 11% of normal patients (P<0.001).
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