Aneurysm of an Anomalous Right Subclavian Artery

Abstract

An anomalous right subclavian artery arising as the fourth branch from the left side of the aortic arch is one of the most common anomalies of the great vessels. The frequency of recorded examples has recently increased due to greater interest on the part of surgeons in cardiovascular disorders. Felson et al. (5) covered the subject thoroughly in their report of 9 cases. Copleman (4) has also published an excellent discussion of the anomaly. The literature thus far fails to show a true aneurysm of this vessel, although a diverticulum of the aorta, often observed at the origin of the anomalous right subclavian, has been referred to as having an aneurysmal origin. In the case to be presented here a true aneurysm of an anomalous right subclavian artery was demonstrated roentgenographically and proved at autopsy. Case History A 50-year-old white male, well developed and well nourished, was admitted to the hospital with pain in the lower abdomen of three weeks duration, intermittent claudication, and impotence. Two and one-half years earlier he had collapsed at work and had been treated for a period of six weeks for a cardiac condition. There was no history of dysphagia at any time. Physical Examination: The patient's blood pressure was 190/110. Funduscopic examination revealed a Grade 2 arteriosclerosis. The lungs were clear, and the heart did not appear enlarged. A systolic murmur was present, transmitted to both subclavicular regions, but most pronounced on the right side. Roentgenological Findings: The postero-anterior chest film revealed a fusiform mass of homogeneous density extending to the right of the mediastinum just above the aortic arch. Fluoroscopic examination showed no pulsation of the mass; it did not move with deglutition nor change in size with the Valsalva maneuver. The barium-filled esophagus was displaced anteriorly and to the right, with a wide pressure defect extending obliquely upward from left to right. The anterior displacement of the esophagus measured 2.5 cm. and the length of the defect 4.5 cm. The trachea was also displaced somewhat anteriorly and to the right and appeared flattened in its anteroposterior diameter. Although the authors knew of no similar case, the esophageal deformity was considered characteristic of aberrant right subclavian artery, and a diagnosis of aneurysm of that artery was made. A chest film obtained two years prior to the first admission was reviewed and appeared entirely normal. A gastrointestinal series showed no evidence of intrinsic disease of the esophagus, stomach, or duodenum. Anterior, posterior, and lateral scout films of the abdomen demonstrated a fusiform dilatation of the aorta with considerable calcification in the wall. Bronchoscopy: Bronchoscopic examination revealed some bulging of the posterior wall of the trachea, slightly diminishing the lumen. The entire tracheobronchial tree danced from transmitted pulsations of the arterial structures.