Angiocardiographic Characteristics of Persistent Common Atrioventricular Canal

PERSISTENT common atrioventricular canal has remained a difficult diagnostic problem because the hemodynamics in this condition may be similar to those of other cardiac malformations or combinations of malformations. Mouquin et al. (1) and Baron and his associates (2) observed, on left ventricular angiocardiograms of these patients, a characteristic deformity of the outflow tract of the left ventricle and stressed the importance of angiocardiography in the diagnosis. Left ventricular angiocardiograms were reviewed in 20 cases of persistent common atrioventricular canal ; in these the diagnosis was established clinically, surgically, and by necropsy. It is the purpose of this review to assess the reliability of angiocardiography in establishing the diagnosis, to delineate the pattern of shunts and valvular regurgitation, and to correlate these with anatomic findings. Angiocardiographic Findings On the left ventricular angiocardiograms of the 20 cases available for review, the commonly seen abnormalities were as follows : (a) Deformity of the left ventricular outflow tract, best seen on frontal films (Fig. 1, A and 2, A) (b) Serrated appearance of the mitral valve best observed on frontal films during ventricular systole and closure of the mitral valve (Fig. 1, A) (c) A small “filling defect” at the midposition of the line of closure of the mitral valve, resulting in a “notch” (Fig. 2, B) (d) An abnormal angiocardiographic appearance of the mitral valve on lateral studies, resulting in a well circumscribed radiolucency (Fig. 1, B) superimposed on the left ventricular outflow tract. Table I summarizes these features which were present in 18 of 20 cases. It is evident that the serrations of the mitral valve, the “notch,” and the abnormal appearance of the mitral valve on lateral film studies are far less consistent angiocardio-graphic findings than the left ventricular outflow tract deformity which was observed in 18 cases. In 2 patients in whom characteristic findings were absent left ventricular angiocardiography was performed after successful surgical correction of the defect. Mitral valvular incompetence was present in 13 of the 20 examined patients. In 7 the contrast medium appeared to regurgitate directly into the left atrium ; in 2 others, directly into the right atrium without visualization of the left atrial chamber. In 2 cases a ventricular component to the defect was clearly demonstrated by visualization of a ventricular septal defect with immediate opacification of the right ventricle. In 1 instance, however, it was not clear whether the right ventricular cavity was opacified directly through a ventricular septal defect or from the right atrium. In this patient the right atrium was opacified through regurgitation of the contrast medium from the left ventricle into the atria.