Right Aortic Arch

Abstract

Right aortic arch is a rare anomaly, the diagnosis of which is seldom established during life. Paradoxically, it is the easiest of all the congenital anomalies of the circulatory system to recognize with certainty. This can be accomplished immediately in practically all cases in which a complete roentgenologic examination of the heart can be made. The importance of this becomes more manifest when we realize that the diagnosis cannot be established with any reliance by the usual clinical procedures. All cases familiar to the writer, which have been identified prior to the findings of the autopsy table, were diagnosed through the use of the roentgen ray. However, there is a strong likelihood that many cases of right aortic arch have passed through the hands of the roentgenologist without having been recognized. The factors responsible for this condition are not hard to find: (1) Elimination of fluoroscopy from the examination; (2) restriction of the radiographic examination to the postero-anterior film; (3) failure to consider barium studies of the esophagus as a part of the cardiac examination—particularly in obscure cases. The object of the present paper is not so much to add another case to the literature of this rare anomaly as to forward a plea for a complete examination of all cardiac cases. The writer is of the firm opinion that not less than two exposures are necessary for even a cursory examination of the heart. The ones of greatest value can never be determined in advance, the selection requiring a preliminary fluoroscopy. The fluoroscopy employing the different oblique positions and including barium studies of the esophagus should be carried out in every complete cardiac examination in which an abnormality of the arch or one of the great vessels is suspected. Excellent reviews of the embryology of this anomaly are found in other articles, and no attempt to redescribe these aspects will be made except to remind the reader that of the six paired aortic arches of the embryo, the fourth left aortic arch becomes the definitive arch of the normal adult. Exceptionally in man and constantly in birds the fourth right aortic arch becomes the functioning unit, the left arch undergoing atrophy either in whole or part (Figs. 1 and 2).1 Blackford and others, in 1932, write that at least a hundred cases of this anomaly are on record. The few identified during life have been reported almost exclusively in foreign periodicals. Notable exceptions to these are the cases of Blackford (3), Jenkinson (7), and Sprague, Ernlund, and Albright (11). The present case was recognized during the course of a routine gastrointestinal examination, the patient having no cardiac complaints. Clinical History.—The patient was a woman of 45 years, who entered the hospital with a history of gradual failure of health since hospitalization for sepsis (right arm) nine years before.