Obstruction of superior vena caval pathway after Mustard's repair. Reliable diagnosis by transcutaneous Doppler ultrasound.

Abstract

Superior vena caval pathway obstruction is an important cause of late morbidity and mortality after Mustard''s operation. Clinical detection of such obstruction is frequently difficult because of the development of an extensive collateral venous circulation which decompresses the superior vena cava. As flow is less likely to be normal than pressure, jugualr venous flow profiles were recorded transcutaneously in 34 patients after Mustard''s operation for simple transposition using a bidirectional Doppler blood velocimeter. There was an independent diagnosis by catheterization in 14 cases, 4 of which were restudied after revision of obstruction. Most patients showed a dominant forward flow peak during ventricular diastole and none of these showed any clinical evidence of pathway obstruction. This pattern was considered normal after a Mustard repair, particularly as it was also seen in 4 patients immediately after a revision operation. The jugular flow profile is not the same as in children without heart disease, presumably because of the anatomical differences and the reduction in atrial compliance produced by Mustard''s operation. Jugular venous flow in patients even with mild superior vena caval pathway obstruction differed from that in the unobstructed group by exhibiting either non-pulsatility or, more commonly, a dominant forward flow peak in ventricular systole. This quick, simple and convenient test proved to be diagnostic of the presence or absence of obstruction and as many patients are asymptomatic, is now the most effective way of screening for this complication. It may make catheterization unnecessary.