Rare Cause of Upper Gastrointestinal Bleeding in Intubated Patient

Abstract

INTRODUCTION: An aberrant right subclavian artery (ARSA) is the most common anatomical abnormality of the aortic arch, found in 0.5-1.8% of autopsies. Fistula formation between a non-aneurysmal ARSA and the esophagus is exceptionally rare. We report a fatal case of upper GI bleeding resulting from such a fistula CASE PRESENTATION: A 44 year-old woman with history of hypertension, presented to the ED with rapidly progressive dyspnea. Initial findings included hypothermia (36.3 C), hypotension (97/43), tachypnea (RR 28) and hypoxemia (O2 sat 90% on room air). Chest radiograph showed a right lower lobe infiltrate with pleural effusion. A presumptive diagnosis of pneumonia was made and the patient was placed on broad spectrum antibiotics. The patient rapidly deteriorated and required intubation and mechanical ventilation. The patient underwent tracheostomy on hospital day 18 and had a prolonged course of mechanical ventilation. Two weeks after tracheostomy placement, the patient acutely developed copious bleeding from the mouth, nose, and tracheostomy tube. Patient was brought emergently to the operating room. A median sternotomy was performed and dissection was extended along the ascending aorta to the 1st branch that was noted to be a bicarotid trunk. In the absence of a trachea-carotid fistula, it was concluded that the patient's bleeding originated from an anomalous origin of the right subclavian artery arising from the proximal descending thoracic aorta and coursing behind the esophagus. The patient underwent emergent computed tomography scan with contrast that confirmed the diagnosis and returned to the operating room where she had a cardiac arrest and failed resuscitative measures DISCUSSION: Embryologically, ARSA is due to interruption of the fourth right aortic arch between the notches for the common carotid artery and subclavian artery while the left fourth arch remains intact. The mechanism underlying the development of a fistula involves the induction of limited necrosis of the digestive and arterial walls by pulsatile compression of the esophageal wall between the ARSA and rigid intubation catheter. This leads to thrombosis of the vasa vasorum as well as to ischemia of the digestive wall. With time, this leads to fistula formation CONCLUSIONS: ARSAE fistula is so rare and difficult to identify, the condition should be considered in intubated patients with hemodynamically significant GI bleeding.