Assessment of the Reconstructed Pulmonary Circulation With Lung Perfusion Scintigraphy After Unifocalization and Repair of Tetralogy of Fallot With Major Aortopulmonary Collaterals

Abstract

Background: Pulmonary vascular supply in tetralogy of Fallot (TOF) with major aortopulmonary collaterals (MAPCAs) is highly variable. Our approach to surgical management of this condition emphasizes early repair including unifocalization and reconstruction of the pulmonary circulation, incorporating all lung segments and addressing stenoses both proximal to and within the lung, in addition to ventricular septal defect closure. At our institution, we have over 15 years of experience using lung perfusion scintigraphy (LPS) to assess the distribution of pulmonary blood flow after complete unifocalization and repair. Methods: We reviewed clinical and quantitative LPS data in 310 patients who underwent complete unifocalization and repair of TOF/MAPCAs from 2003 to 2018 at our institution. Postrepair relative lung perfusion distributions were determined from LPS initially obtained at our institution within 60 days after repair and thereafter. Results: Total lung perfusion to the right and left lungs was 58.0% + 14.2% and 42.0% + 14.2%, respectively. Perfusion was balanced in 75% of patients and unbalanced in 25%, including 11% in whom it was extremely unbalanced. On multivariable analysis, older age at repair, surgery other than a single-stage complete unifocalization, and native anatomy consisting of unilateral pulmonary blood supply through a ductus arteriosus were associated with unbalanced perfusion. Conclusion: We present our experience using LPS as an outcome measure after surgical repair of TOF/ MAPCAs. Balanced lung perfusion was present in the majority of patients who had complete repair of TOF/MAPCAs performed at our center.

Serial Lung Perfusion Scintigraphy After Unifocalization and Repair of Tetralogy of Fallot With Major Aortopulmonary Collaterals

“…In this study, as in our prior investigation, 4 we found that the baseline predischarge LPS was near normal for the overall cohort but varied markedly among patients. In the subset of patients who received follow-up LPS beyond the perioperative period, there was minimal change over time in the population overall, but large changes in some patients and considerable variability.…”

“…The distribution of pulmonary blood flow prior to discharge was similar to that reported in our prior study, 4 with a median of 42.5% of total lung flow to the left lung (25th-75th percentiles, 34.3%-48.9%) and considerable variation among patients. For the population overall, left-right flow distribution was similar at each follow-up window (Figure 1).…”

“…We previously found that lung perfusion distribution did not correlate with significant differences in the post-repair absolute or relative PA pressure, 4 and in this study, changes in perfusion were not associated with PA pressure either. That is not to say that imbalanced perfusion is of no clinical significance, and it will be important to evaluate whether PA perfusion abnormalities are related to later PA pressures or to ventilationperfusion matching and/or exercise cardiopulmonary physiology.…”

“…2,3,[5][6][7][8] Demographic and diagnostic data collected for this study were detailed in a prior report focused on early post-repair LPS. 4…”

“…Unbalanced pulmonary perfusion was defined as described previously (<30% or >60% of total flow to the left lung). 4 Changes in LPS were calculated from the baseline predischarge study as an absolute percentage (eg, if left lung perfusion was 43% of total prior to discharge and 51% of total at six months, the change was recorded as 8%).…”