THE COLLATERAL CIRCULATION IN COARCTATION OF THE AORTA WITH A DISTAL SUBCLAVIAN ARTERY.

Abstract

The collateral circulation in coarctation of the aorta has been of considerable interest because of its importance in the diagnosis of the anomaly. The collateral pathways are well known and have been adequately documented (2, 3). Not so well known, however, are the collateral pathways which accompany a subclavian artery arising distal to the coarcted segment. Case Report F. J., a 43-year-old white male, was admitted to the UCLA Hospital Nov. 28, 1961, complaining of dyspnea on severe exertion since childhood. At the age of twenty-eight he was found to be hypertensive, but only in the left upper extremity. Three months prior to admission anginal pain developed as well as some transient blurring of vision, especially in the left eye. On physical examination the blood pressure in the right arm was 110∕76, in the left arm 180∕90, and in both legs 100∕70. A loud systolic murmur was heard over the entire precordium and back. Neurological findings were normal. Laboratory studies were not remarkable except for a positive double Master's electrocardiographic test. A chest film (Fig. 1) demonstrated moderate enlargement of the heart. A double contour was noted over the aortic knob, and there was notching of only the left sixth through ninth ribs. Aortography (Figs. 2 to 5) revealed a localized coarctation of the aortic arch distal to the origin of a dilated left subclavian artery from which a large left vertebral artery arose. A well developed collateral circulation through the usual channels was demonstrated on the left side. On the right side, however, initial faint filling of the subclavian artery was by way of small, tortuous vessels situated at the root of the neck. Then delayed retrograde flow down the right vertebral artery filled out the right subclavian artery and subsequently the descending thoracic aorta distal to the coarcted segment. A left thoracotomy on Dec. 18 confirmed the above findings. The anomalous right subclavian artery was ligated at its origin. Blood pressure in the upper extremities then increased from 120∕90 to 190∕110 on the right and from 150∕100 to 200∕110 on the left. This elevation was due to the obstruction interposed on the collateral pathway on the right (13, 17). The coarcted segment was excised, and an end-to-end anastomosis successfully accomplished. Postoperatively the patient has done well except for occasional anginal pain. Dyspnea on exertion has improved. The blood pressures on the last visit, in October 1963, were: right ann, 120∕80; left arm, 140∕90; and legs 150∕84. Discussion The anomalous right subclavian artery is a manifestation of a persistent right aortic arch and is the most common anomaly of the great vessels (1, 10). Edwards (10) reports a frequency of 0.5 per cent in 3,739 consecutive autopsies.