Diagnosis of increased pulmonary blood flow by suprasternal M-mode echocardiography in atrial septal defect

The right pulmonary artery (PA) was quantitatively assessed by Suprasternal M-mode echocardiography in 25 patients in whom an atrial septal defect (ASD) was suspected clinically. In 10 patients an ASD was excluded (Group 1) and in 15 it was confirmed (Group 2). The smallest diameter of the right PA at end-diastole in Group 1 was 8.8 ± 1.5 mm/m² body surface area and in Group 2 14.8 ± 3.6 mm/m² (p < 0.001). The greatest diameter of the right PA during systole was also much smaller in Group 1 (11.3 ± 1.2 mm/m²) than in Group 2 (17.7 ± 3.5 mm/m²) (p < 0.001). The absolute and percent systolic expansion of the right PA did not differ in the 2 groups (2.7 ± 0.5 mm [29.1 ± 10.8%] in Group 1 and 2.9 ± 0.8 mm [20.8 ± 9.8%] in Group 2). No correlation was found between measured and derived echocardiographic variables of the right PA and the magnitude of the left-to-right shunt. Patients in Group 2, who had an additional pressure elevation in the PA, showed, on average, a larger right PA and a smaller percent systolic expansion. The study demonstrates characteristic alterations in the wall motion pattern of the right PA in patients with ASD, indicating increased pulmonary blood flow.