Relationship Between Aortic Root Enlargement and Pulmonary Blood Flow in Pulmonary Atresia With Major Aortopulmonary Collateral Arteries

<h2>Abstract</h2><h3>Background</h3> Patients with pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (PA/VSD/MAPCAs) have markedly enlarged aortas compared with standard control subjects. Previous studies have suggested that aortic enlargement may be attributable to a combination of increased flow and intrinsic aortopathy. We hypothesized that aortic sizes in patients with PA/VSD/MAPCAs would correlate with the ratio of pulmonary to systemic blood flow (Q_p/Q_s) values. <h3>Methods</h3> This was a retrospective review of 169 patients with PA/VSD/MAPCAs who underwent a surgical procedure. Echocardiographic studies were reviewed to assess aortic root size and z-scores. The Q_p/Q_s values were gleaned from preoperative cardiac catheterization. Patients were divided into 3 subgroups: single-stage complete repair, unifocalization and shunt, and aortopulmonary window. <h3>Results</h3> Median age at surgery was 6.1 months for the single-stage complete repair group, 5.9 months for the unifocalization and shunt group, and 1.9 months for the aortopulmonary window group. Patients who underwent a single-stage complete repair had higher Q_p/Q_s values (1.78 vs 0.94, 0.93; <i>P</i> < .001), higher absolute aortic root measurements (1.95 cm vs 1.66, 1.52; <i>P</i> < .05), and higher aortic root z-scores (5.81 vs 1.10, 2.92; <i>P</i> < .01) compared with patients who underwent unifocalization and shunt procedure and aortopulmonary window procedures. However, within each subgroup there was no correlation between Q_p/Q_s and either aortic root size or aortic root z-scores. <h3>Conclusions</h3> The data demonstrate that there were 3 distinct anatomic and physiologic patterns for the 3 subgroups. Within each subgroup, no correlation was found between Q_p/Q_s and either aortic root size or z-score. These results suggest that incremental increases in flow do not result in additional increases in aortic size.