The pulmonary pressures in pulmonary venous obstruction.

The contour of the pulmonary artery wedge pressure tracing in a case of pulmonary venous obstruction was unique and may be diagnostic. Wedged pressures were obtained in both a pulmonary artery and a pulmonary vein on recatheterization of a 5-yearold boy with total anomalous pulmonary venous drainage to the superior vena cava on whom an anastomosis of the confluence of the pulmonary veins to the left atrium with loose ligation of the vertical vein had been done at 2 months of age. The pulmonary artery wedge pressure (oxygen saturation, 97%) was 31/18 (mean, 22) mm Hg and its contour was almost identical to that of the pulmonary artery pressure. A similar contour was obtained in the pulmonary vein, for both wedged and free pressures. The similarity of the pulmonary artery wedge pressure to that in the free pulmonary artery may lead to the conclusion that the catheter is not wedged when actually it is. Doubt can be resolved by withdrawing fully saturated blood. Extreme stenosis between the confluence of the pulmonary veins and the left atrium may cause the pulmonary artery wedge to reflect pulmonary arterial rather than left atrial pressure and pulse form.