Hemodynamic studies in children four to ten years after the Mustard operation for transposition of the great arteries.

Fourteen patients have been studied hemodynamically 4-10 years (mean 5.5 years) after the Mustard operation for transposition of the great arteries. Investigation was directed principally at 1) the detection of baffle obstruction by catheterization of the pulmonary veins (PV) and venae cavae and recording of simultaneous right ventricular (RV) and pulmonary capillary wedge pressures (PCW); 2) the detection of intra-atrial baffle leaks by dye curves and selective angiography; 3) the assessment of RV and LV function by calculating peak VCE (dp/dt/28p) from high fidelity recordings in 11 patients. Severe baffle obstruction to the PV return was found in only one patient. The others had no or minimal gradients between RV end-diastolic and PCW pressures (mean 1.3 +/- 0.69 mm Hg). Cardiac output was normal at rest (4.1 +/- .22) and increased to 7.1 +/- .62 L/min/m2 (+73%) but the gradient between the RV end-diastolic and PCW pressures remained insignificant (2.2 +/- 1.13 mm Hg). No evidence of caval obstruction was found in any patient. Baffle leaks were found in five patients with mild bidirectional shunting. All arterial oxygen saturations were above 90%. Mild tricuspid regurgitation was demonstrated in two patients by RV angiography and was absent in 12 others. The contractility index peak VCE averaged 1.87 +/- .122 sec-1 for the RV and was significantly lower in the LV (1.53 +/- 1.35 SEC-1, P less than 0.01). Only one patient presented significantly decreased RV contractility with a peak VCE of 1.07 sec-1 and poor contraction on the RV angiogram. These data indicate that the long-term prognosis after the Mustard operation should be good in most patients and that the right ventricle is capable of functioning at the level of contractility of a normal left ventricle.