Multidisciplinary Approach to Aneurysmal Anomalous Systemic Artery to Normal Lung: A Case Report

Only fifty-one cases of isolated anomalous systemic arterial supply to normal lung (ISSNL) have been reported in English literature (1). The anomalous systemic artery usually arises from the descending thoracic aorta, but rarely from the abdominal aorta. In this article and accompanying video, a rare case of an anomalous artery occurring from the right inferior phrenic artery is reported. The aneurysmal nature of the anomalous artery in the patient is also a rare but significant finding, as it increases the risk of rupture (1). Additionally, the patient’s condition may be categorized as an arterial pulmonary malinosculation, which is defined as an area of lung with systemic supply but normal bronchopulmonary airway (2).

The majority of patients with ISSNL remain asymptomatic but are at risk of developing haemoptysis, pulmonary hypertension, and congestive heart failure because of the persistent left-to-left shunt (3). Conservative management has been described in asymptomatic patients (1). Recently, there is growing interest in utilizing TAE to occlude the culprit artery (3). However, there is a theoretical risk of pulmonary infarction, especially if pulmonary arterial supply is lacking. As such, embolization was considered in this case to simultaneously minimize intraoperative bleeding should the artery retract upon ligation and minimize the risk of rupture of the residual ligated aneurysmatic vessel.

Sublobar resections have been supported, as they provide the benefit of lung volume preservation, but lobectomy remains the most reported method of intervention (4). Reanastomosis of the aberrant artery to the pulmonary arterial system has also been described with limited result, especially in older patients where the aberrant artery becomes thickened and sclerotic because of prolonged exposure to systemic pressures (5). In this case, surgeons decided to proceed with a right lower lobectomy for the patient, as there was global right lower lobe (RLL) parenchymal thickening and infarction after the initial embolization.

 The Patient

This video presents the case of a fifty-four-year-old woman with an incidental finding of an anomalous systemic artery supplying the lower lobe of her right lung (RLL), with atresia of the pulmonary arteries to segments 9 and 10. However, there were normal segmental bronchial branching patterns in the right lower lobe, and no distinct pulmonary sequestration was identified on initial computed tomography (CT) pulmonary angiogram. 

A subsequent CT aortogram revealed that the anomalous artery arose from a hypertrophic right inferior phrenic artery, independent of the coeliac axis. The artery contained a 14 mm aneurysmal portion extending from below the right hemidiaphragm until its bifurcation inside the right lower lobe. Venous drainage of the right lower lobe was happening via the right inferior pulmonary vein (IPV). A small branch was also found to supply the superior aspect of the liver but was deemed to be insignificant. 

The Surgery

Surgeons first proceeded with transarterial embolization (TAE) to reduce the risk of significant intraoperative bleeding. Distal embolization was first performed, but this inadvertently increased pressures proximal to the coils, including the aneurysmal section. A second proximal coil embolization was therefore performed, achieving near complete occlusion of the vessel.

Next, a standard right-sided three-port video assisted thoracoscopic surgery (VATS) was performed. On inspection, segments 9 and 10 were separated from the rest of the RLL within a pseudocavity formed by an abnormal septum. The anomalous artery was secured with a size 0 silk ligature to provide proximal control. It was then divided with a 45 mm vascular stapler. A right lower lobectomy was then conducted in the standard fashion. 

The chest drain was removed on postoperative day two (POD2) and the patient was discharged on POD 4. She re-presented two days after discharge with self-limiting surgical emphysema, but no reintervention was required. Postoperative histology revealed multiple thick-walled aneurysmal arteries in the lower lobe with parenchymal changes in keeping with infarction after arterial embolization. 

References

1. Wee N, H’ng M, Punamiya S. Isolated Systemic Arterial Supply to Normal Lung with Aneurysm Formation: A Rare Entity with An Even Rarer Complication. American Journal of Case Reports. 2020;21.
2. Clements B, Warner J. Pulmonary sequestration and related congenital bronchopulmonary-vascular malformations: nomenclature and classification based on anatomical and embryological considerations. Thorax. 1987;42(6):401-408.
3. Anil G, Taneja M, Tan A. Endovascular treatment of isolated systemic arterial supply to normal lung with coil and glue embolisation. The British Journal of Radiology. 2012;85(1012):e83-e86.
4. Iizasa T, Haga Y, Hiroshima K, Fujisawa T. Systemic arterial supply to the left basal segment without the pulmonary artery: four consecutive cases. European Journal of Cardio-Thoracic Surgery. 2003;23(5):847-849.
5. Kim D, Jeong I, Kim J, Kim Y, Cho H. Operation for an anomalous systemic arterial supply to the left lower lobe using an anastomosis procedure in an infant. Journal of Thoracic Disease. 2018;10(4):E301-E303.

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