Unifocalization of Major Aortopulmonary Collateral Arteries

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This is a case presentation of a 17-month-old male infant born with tetralogy of Fallot, with five distinct major aortopulmonary collateral arteries (MAPCA).  

A three-dimensional rendering of the patient’s complex cardiac anatomy was created to assist in surgical planning. The main MAPCA originated from the descending aorta and trifurcated into three branches. The second branch of the main MAPCA supplied oxygenated blood to the entirety of the left upper lobe and the superior segment of the left lingula. The third branch coursed leftward and included branches that served as the sole blood source for the posterior basal segment of the left lower lobe before inserting onto the central left pulmonary artery and continuing into the main pulmonary artery. The first branch provided sole blood supply to the posterior segment of the right upper lobe and the superior segment of the right lower lobe, in addition to the smaller right lung segments. Due to limitations in the video software, MAPCAs other than the main branch could not be visualized due to either their size or their location.  

Additional CT imaging of the chest provided confirmation of tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries. It revealed a large anterior malaligned ventricular septal defect involving the perimembranous septum, a severely narrowed right ventricular outflow tract, a hypoplastic left pulmonary artery, and a normal right pulmonary artery. The imaging also showed a patent foramen ovale and a mildly dilated and hypertrophied right ventricle. The second MAPCA originated from the left main coronary artery and inserted directly into the central main pulmonary artery. The third MAPCA provided the sole blood supply to the lateral basal and anterior medial basal segments of the left lower lobe and supplied a portion of the basal segment not supplied by the third branch of the main MAPCA arising from the descending aorta. The fourth MAPCA provided the sole blood supply to the inferior lingula section of the left lung and the superior segment of the left lower lobe. The fifth MAPCA was small and had branches to areas of the right lung supplied by other MAPCAs. 

The cardiothoracic surgical team elected to perform a unifocalization of the first and fourth MAPCAs since these vessels were large enough in diameter for surgical intervention. This was accompanied by closure of the large perimembranous ventricular septal defect using a fenestrated (2-3 mm) patch and placement of a right ventricle-to-pulmonary artery conduit. The fenestration was intended to provide an outlet in instances of elevated right ventricular pressures and to reduce the likelihood of right ventricular remodeling. 

Surgery 

The patient was prepped for surgery and a median sternotomy occurred in the standard fashion. Following the opening of the pericardium, the first MAPCA was dissected free at its proximal portion, and two branches were further dissected down to their periphery. Note that the narrowing of the branches at the proximal portion became larger and more suitable for intervention at the periphery. The second MAPCA was dissected away from the left coronary artery and appeared to be a main pulmonary artery. At this time, the patient was heparinized, cannulated bicavally, and cardiopulmonary bypass commenced in the standard fashion. 

Attention was then directed back toward the unifocalization of the collateral blood flow. The first MAPCA was clipped, the second MAPCA was secured with a tie just distal to its connection with the left coronary artery, and the third MAPCA was clipped, although it appeared to be already obstructed. The most inferior collateral arteries on the left side were further mobilized and divided away from their source to file them for anastomosis using 7-0 Prolene sutures. Next, a corresponding arteriotomy was made on the anatomic left pulmonary artery, and the collaterals were secured using 7-0 Prolene in a running fashion. A 2 mm probe was then passed through and observed to be widely patent and without obstruction.  

Attention was then directed to the branch of the first MAPCA that traversed to the right lung, which was observed to bifurcate proximal to the insertion site within the right upper lobe. For proper surgical planning, a segment of the posterior MAPCA branch and the anterior right pulmonary artery were marked with a surgical pen to account for the site of anastomosis. The MAPCA branches were then divided proximal to their insertion and opened on their posterior surfaces. A corresponding arteriotomy was created on the anatomical right pulmonary artery and was then anastomosed to the previous collateral using 7-0 Prolene sutures. A 5 mm dilator was passed, showing no signs of obstruction.  

Following the unifocalization of the collateral arteries, attention was directed to the right ventricular outflow tract for the sequential closure of a perimembranous ventricular septal defect. This segment of the case was left out as the main purpose of this case report was the unifocalization of the major aortopulmonary collateral arteries. After deairing and ensuring adequate hemostasis, the cross-clamp was removed, and the patient was separated from cardiopulmonary bypass and closed in the standard fashion. The patient was then transferred to the cardiovascular intensive care unit on Milrinone after being extubated. 

Postoperative 

Cardiopulmonary bypass time was 99 minutes, and aortic cross-clamp time was 35 minutes. Postoperative transesophageal echocardiogram (TEE) confirmed the unifocalization of the collateral arteries.  Additional findings illustrated a small residual left-to-right shunt with a peak gradient of 19.9 mmHg across the ventricular septal defect patch fenestration. There was no right ventricular outflow tract stenosis or regurgitation, and the cavity size and systolic function of both the left and right ventricles were normal.  

Chest tubes and pacing wires were removed on postoperative day three, and the patient was discharged from the cardiovascular intensive care unit on day 19. 

References

1. Alex A, Ayyappan A, Valakkada J, Kramadhari H, Sasikumar D, Menon S. Major Aortopulmonary Collateral Arteries. Radiol Cardiothorac Imaging. 2022 Feb 3;4(1):e210157. doi: 10.1148/ryct.210157. PMID: 35782757; PMCID: PMC8893210.

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