[Quantitative evaluation of left heart obstructions (including aortic isthmus stenosis) in children using Doppler echocardiography].

To assess the accuracy of pulsed and continuous-wave Doppler echocardiography (DE) in evaluating pressure drops across left heart outflow obstructions we examined 27 children with valvular aortic stenosis (n = 13), fixed subaortic stenosis (n = 14) and 16 children with coarctation. Doppler examination was performed within 24 hours of cardiac catheterization in 15 patients, in 17 patients 2-42 months (mean 13 months) after catheterization. Simultaneous blood pressure measurements in both upper and lower limbs with an automated oscillometer were taken in 12 cases with coarctation. Using three standard positions (suprasternal, high right parasternal and apical) we found a close Doppler-catheter correlation in patients with aortic and subaortic stenosis (r = 0.94). The correlation in cases with coarctation was poor (r = 0.17) because of one patient with severe stenosis and another with atresia and a huge collateral vascularization, in whom a poststenotic jet could not be located. Surprisingly the postoperative pressure gradient was much overestimated in one of these patients by DE. We conclude that a "multi-channel system" due to collateral vascularization excludes the use of the simplified Bernoulli equation. Apart from these anatomically related false Doppler estimates we found a good correlation (r = 0.90), with slight overestimation in mild stenosis. Thus, Doppler ultrasound provides an accurate noninvasive method for estimating pressure gradients in patients with aortic and subaortic stenosis and to a lesser extent in patients with coarctation. In particular DE is helpful for determining subsequent clinical management.