RIGHT-TO-LEFT SHUNT ACROSS ATRIAL SEPTAL-DEFECT RELATED TO TRICUSPID REGURGITATION - ASSESSMENT BY TRANSESOPHAGEAL DOPPLER-ECHOCARDIOGRAPHY

The purpose of this study was to assess the factors involved in the de velopment of the right-to-left (R-L) shunt in patients with atrial sep tal defect (ASD), especially the role of tricuspid regurgitation (TR). Thirty-one consecutive patients with ASD underwent transesophageal Do ppler echocardiography to determine the size of ASD, the shunt flow, a nd the TR flow, and they were compared with hemodynamics examined by c ardiac catheterization. Sixteen patients with the R-L shunt were older (53 +/- 11 vs 34 +/- 9 years; p < 0.001) and had higher pulmonary art erial pressure (36 +/- 17 vs 25 +/- 5 mmHg; p < 0.05) and a greater Qp /Qs (3.6 +/- 1.2 vs 2.4 +/- 0.9 L/min; p < 0.01) as compared with 15 p atients with the pure left-to-right shunt. In six of 21 patients with TR, the regurgitant flow oriented toward ASD and blew into the left at rium through the defect. Besides the deviation of TR flow, the prevale nces of the maximum diameter of ASD >2.5 cm and the maximal TR flow ar ea >4 cm(2) were significantly higher in the six patients as compared with patients with TR not related to the R-L shunt (p < 0.05 and p < 0 .05), despite the pulmonary arterial pressure being similar in the two groups. Reversal of pressure gradient between the left and right atri um was not observed during the cardiac cycle in all patients. In concl usion, TR is a determinant of the R-L shunt in patients with ASD even in the absence of the reversal of pressure gradient between the left a nd right atrium.