Pulmonary Segmental Artery Ratio An Alternative to the Pulmonary Artery Index in Patients With Tetralogy of Fallot

Abstract

The objective of this study was to determine a reliable, alternative ratio to the pulmonary artery (PA) index, which will help to estimate the adequacy of postoperative pulmonary blood flow in patients with tetralogy of Fallot. We propose the pulmonary segmental artery ratio (PSAR), which is an angiographic measure for the quantitative standardization of the total number of pulmonary segmental arteries in a patient. The expected value of the PSAR is 1 and it is constant after the 16(th) week of intrauterine life. Retrospective analysis of the PSAR and PA index calculations in patients with tetralogy of Fallot was conducted. Sixty-one patients were assigned to a moderate or low risk group according to their PSAR; the low risk group included 31 patients whose PSAR was between 0.75-1 (group 1) while the moderate risk group included 30 patients whose PSAR was between 0.50-0.75 (group 2). High risk patients whose PSAR was less than 0.50 were excluded from the study. Postoperative peak right ventricular pressure, the pulmonary artery to systemic pressure ratio, and peripheral arterial oxygen saturation preoperatively after cardiopulmonary bypass were analyzed separately in groups 1 and 2. Postoperative peak right ventricular pressure was lower in group 1 than group 2, while the pulmonary artery to systemic pressure ratio and peripheral arterial oxygen saturation were higher in group 1 than group 2 (P < 0.01). Based on the present findings, it is concluded that PSAR is not as reliable as the Nakata index. However, in cases in which the PSAR and PA index are not correlated, PSAR may be helpful for determining the adequacy of postoperative pulmonary blood flow and postoperative outcomes of patients with hypoplastic pulmonary arteries.