[Cardiovascular magnetic resonance evaluation of left-to-right shunts due to cardiac septal defects in patients with pulmonary arterial hypertension].

Introduction And Objectives: As cardiac septal defects are frequently associated with pulmonary arterial hypertension, hemodynamic assessment is essential before deciding on surgery. The aim of this study was to evaluate the use of cardiovascular magnetic resonance imaging for assessing cardiac shunts and for quantifying pulmonary artery systolic pressure in patients with cardiac septal defects.

Methods: This cross-sectional study involved patients with cardiac septal defects and clinically suspected severe pulmonary arterial hypertension who had an indication for cardiac catheterization and in whom magnetic resonance imaging was not contraindicated. Each test's results were evaluated independently by two expert radiologists and interventional cardiologists who were blinded to the results of the other test. The procedures were compared using confidence limits and intraclass correlation coefficients.

Results: The study involved 29 patients (18 female and 11 male) aged from 30 days to 18 years; seven had an atrial septal defect, 14 had a ventricular septal defect, and eight had an atrioventricular septal defect. The correlation coefficients for measurements made using the two procedures were 0.80, 0.75, 0.81 and 0.58 for pulmonary output, systemic output, flow ratio, and systolic pressure in the pulmonary artery, respectively. Cardiovascular magnetic resonance tended to underestimate systemic output by 0.80 L/min, pulmonary output by 1.35 L/min, left-to-right shunt flow by 0.12 L/min, and systolic pressure in the pulmonary artery by 16.5 mmHg. The complication rate with cardiac catheterization was 31% compared with 3.4% with cardiovascular magnetic resonance imaging.

Conclusions: The evaluation of patients with cardiac septal defects and pulmonary arterial hypertension should initially be performed using noninvasive diagnostic techniques.