Anomalous Right Subclavian Artery

Abstract

Anomalous right subclavian artery, originating as the last vessel from the aortic arch, is one of the commonest anomalies of the great vessels. Anatomists have been familiar with this condition for more than two centuries, yet few clinicians are aware of its existence. Despite its frequency and the ease with which it can be detected roentgenologically, the correct diagnosis is seldom made during life. This is due, in part, to the fact that the anomaly is usually asymptomatic. Occasionally, however, severe symptoms may develop and progress to a fatal outcome. This anomaly has assumed greater significance with the advent of the surgical approach to the treatment of congenital malformations of the heart and great vessels. Gross (12), in 1946, successfully ligated an anomalous right subclavian artery. Since that time he has surgically cured 4 additional patients with symptoms related to this cause (13). Blalock (5) encountered the anomaly five times during operations on patients with the tetralogy of Fallot, but the abnormal position of the artery did not interfere with its use for the anastomosis. Humphreys, however, discussing Blalock's paper, stated that he had lost one patient during the Blalock operation because the right subclavian artery was anomalous. Although Bayford (4) is usually credited with the first description of this condition in 1789, Holzapfel (18) gives priority to Hunauld for his account in 1735. Bayford applied the term dysphagia lusoria to the presenting complaint in his patient, “from the lusus naturae (freak of nature) that gives rise to it.” In 1936, Kommerell (19) reported the first case diagnosed by roentgen methods. Incidence In Maude Abbott's series of 1,000 autopsied cases of congenital heart disease (1), anomalous right subclavian artery occurred seven times. Various authors have reported the incidence in autopsy series as from 0.4 up to 2.0 per cent. Cairney (6), in a review of the literature up to 1924, found more than 230 cases. In the few instances in which it was diagnosed during life, the anomalous artery was detected by roentgenologic methods. Individual cases have been reported by Kommerell (19), Zdansky (26), Günsel (15), Copleman (7), and Stauffer and Pote (23). Dahm (8) reported 2 cases. Brean and Neuhauser (27) reported 15 cases in 1947, and since that time have seen approximately 15 more (21). During the past two years we have encountered 9 patients in whom the typical roentgen findings were present. Embryology In the five-week embryo there are 6 pairs of arches connecting the ventral and dorsal paired aortas (7). During the normal development of the fetus, certain segments of this network of vessels disappear, while other branches persist to form the aorta and main arteries (Fig. 1).