Pulsed Doppler assessment of left ventricular diastolic filling in children with left ventricular outflow obstruction before and after balloon angioplasty

Abstract

To assess left ventricular (LV) diastolic filling in children with pressure overload hypertrophy, 12 patients with LV outflow obstruction (7 with aortic valve stenosis and 5 with aortic coarctation) and 12 healthy, age-matched control subjects were examined. Each child underwent M-mode echocardiography and pulsed Doppler examination of the LV inflow. The patients with LV outflow obstruction had cardiac catheterization and balloon angioplasty. Their echo/Doppler examinations were performed in the catheterization laboratory before and immediately after balloon angioplasty. From the M-mode echocardiogram, the LV cavity dimensions and wall thicknesses, LV mass and shortening fraction were measured. The following measurements were made from the Doppler recording: peak velocities at rapid ventricular filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, total area under the Doppler curve, percent of the total Doppler area occurring in the first one-third of diastole (0.33 area fraction), percent of the total area occurring under the E wave (E area fraction), percent of the total area occurring under the A wave (A area fraction) and the ratio of E area to A area.Before balloon angioplasty, the patients with LV outflow obstruction had higher peak E velocity (1.06 +/- 0.18 vs 0.88 +/- 0.11 m/s, p < 0.01), higher peak A velocity (0.86 +/- 0.22 vs 0.47 +/- 0.08 m/s, p < 0.01) and lower E/A velocity ratio (1.29 +/- 0.27 vs 1.93 +/- 0.34, p < 0.01) than the normal subjects. In the patient group, 0.33 area fraction was significantly lower (0.38 +/- 0.07 vs 0.57 +/- 0.09, p < 0.01) and A area fraction was significantly higher (0.44 +/- 0.14 vs 0.23 +/- 0.07, p < 0.01) than in the normal subjects. Also, patients with LV outflow obstruction had greater LV wall thickness, smaller LV cavity dimensions and greater LV mass compared with normal subjects. In patients before and after balloon angioplasty, there was a significant decrease in LV outflow gradient (64 +/- 23 vs 33 +/- 22 mm Hg, p < 0.01), but there was no change in any echo/Doppler measurement. Thus, children with LV outflow obstruction have abnormal LV early diastolic relaxation with a shift in filling toward late diastole. Immediately after successful relief of the systolic pressure overload, diastolic filling patterns are unchanged, suggesting that hypertrophy rather than afterload mismatch is the primary determinant of the impaired relaxation.