[Continuous-wave Doppler velocimeters and blood pressure difference in aortic coarctation. A simultaneous comparative study of 52 children].

Sixty examinations in 52 children with coarctation of the aorta (eight pre- and postoperative studies) were performed to assess the relation of the Doppler derived gradient using the simplified Bernoulli equation (delta p = V2 X 4) with the blood pressure difference simultaneously measured with an automated oscillometer. There was a close correlation (r = 0.89, y = 16.1 + 0.73x, syx = 7.38 mmHg) with significant overestimation of the blood pressure difference in mild stenoses (p less than 0.0001). If the patients are divided in two groups, an operative (group 1: symptomatic patients, n = 24) and a nonoperative group (group 2: asymptomatic patients, in the majority recoarctations, n = 36) it becomes clear that the overestimation is due to the latter. The velocity superior to the coarctation was higher in the second than in the first group (152.1 +/- 31.5 vs. 114.5 +/- 43 cm/s, p less than 0.004) (mean +/- SD). If the prestenotic velocities are taken into account, the correlation is nearly the same (n = 37, r = 0.9, y = 9.4 + 0.73x, syx = 7.3 mmHg) with slight underestimation in high-grade and overestimation in mild coarctations. A pandiastolic increased velocity was found in 79% of the patients in the operative group, but in none of the nonoperative group. The reasons for the overproportional increased jet velocity in group 2 as discussed are that: the peak pressure gradient may exceed the peak-to-peak pressure gradient; the prestenotic velocity must be taken into account, if the modified Bernoulli equation is used; and the collateral vascularization may be substantial.(ABSTRACT TRUNCATED AT 250 WORDS)