ABNORMAL RHYTHMS ASSOCIATED WITH PERSISTENT LEFT SUPERIOR VENA CAVA

Extract: The electrocardiograms of 26 patients with persistent left superior vena cava (SVC) draining into the coronary sinus were reviewed. Left axis of P waves between +15 and -29 degrees was observed in nine cases, including two of three cases of persistent left SVG with absent right SVC. Isorhythmic A-V dissociation with interference was observed in one subject. The study of the P wave in five groups of patients with presumably normal caval drainage revealed that frontal P wave axis fell usually between +20 and +70 degrees. Speculation:Left axis of the P waves, if present in patients with congenital heart defects, may suggest persistent left superior vena cava draining to the coronary sinus. Further pathologic and histologic study is needed to clarify the pathogenesis of these abnormal cardiac rhythms and the possible embryologic relation between persistent left superior vena cava and an ectopic pacemaker. © International Pediatrics Research Foundation, Inc. 1969. All Rights Reserved.