Correction of single and common atrium, with reference to simplified terminology.

and hemodyhamic features of five cases of surgically proved complete absence of the atrial septum are presented. Technical details of the method of correcting this malformation are described. At foUow up, all are alive and well. It is suggested to subdivide this entity into two: single atrium, when complete absence of the atrial septum is found but the atrioventricular valves are normal, and common atrium, in which, in addition to the absence of atrial septum, endocardial cushion defect is also present. C omplete absence of the atrial septum is rare and is considered to be the least common variety of atrial septal defect.'.* In the literature there would appear to be some nosologic confusion in the use of terms such as cor triloculare-biventriculare, common atrium, or single atrium. In this article, the term single atrium is used to denote the condition comprising: 1) complete absence of the atrial septum, 2) absence of malformation of the atrio-ventricular valves and 3) absence of interventricular communication. The term, common atrium, is used to denote the condition of complete absence of the atrial septum, accompanied by malformation of the atrioventricular valves, with or without interventricular communication. The conditions of common atrium and ostiurn pri-mum defect may therefore be considered to constitute two varieties of the partial or complete atrioventricu-lark communis defects. This report concerns five patients with complete absence of the atrial septum. One case was of the single atrium type, four were of the common atrium variety. During the period 1967-1970, h e patients with complete absence of the atrial septum underwent corrective surgery in our department. Their ages ranged from 8-34 years. There were two males and three females. Symptoms of fatigue, dyspnea and peripheral cyanosis were present in all four patients with common atrium, while the patient with single atrium was asymptomatic. The physical findings in the four patients with common atrium were a fixed split second pulmonary sound, a soft tricuspid diastolic flow murmur; a soft systolic murmur over the pulmonary area; and a grade 2 4/6 systolic murmur over the cardiac apex, radiating towards the axilla. In the patient with single atrium the physical findings were similar, except for the absence of the apical systolic murmur. The ECG in all five patients showed a prolonged PR interval, left axis deviation and evidence of right ventric-ular hypertrophy. The catheterization data are shown in Table 1. Repair was undertaken using extracorporeal …