II. Atrial Septal Defect. Analysis of One Hundred Cases Studied During Life

¹ The Divisions of Pediatrics and Medicine, Hahnemann Medical College and Hospital, and the Bailey Thoracic Clinic.

One hundred consecutive patients in whom an atrial septal defect was demonstrated and who were studied by right heart catheterization have been analyzed.

The malformation produces symptoms in the majority of patients. Cardiac failure is common.

The most characteristic roentgen feature is the presence of marked dilatation of the left and right branches of the main pulmonary artery. This is seen much less frequently in other lesions allowing a left to right shunt.

The electrocardiogram shows evidence of right ventricular hypertrophy in a majority. Right bundle branch block is less than one-half as common.

Although pulmonary hypertension is found very frequently, the pressure tends to be lower than it is in ventricular septal defects. The left-to-right shunt, on the other hand, tends to be greater.

The mechanism of development in both atrial and ventricular septal defects of pulmonary hypertension is the same. However, initial and potential flow through a defect in the interventricular septum is greater than that through one of similar size in the atrial septum. The stimulus to pulmonary vascular changes is greater and the necessity more acute in the former.

There are no characteristic historical or physical findings. Although right bundle branch block and marked dilatation of the primary branches of the pulmonary artery in a patient with a systolic murmur at the base allows one to be very suspicious of the presence of an atrial septal defect, the diagnosis depends upon cardiac catheterization.

Patients may be divided into five classes so far as the desirability of surgical closure is concerned. The magnitude and direction of shunt through the defect and the height of pulmonary pressure are the basic considerations.

Defects in the septum just above the atrio-ventricular valves are extremely difficult to close if there is not at least a small rim of septal tissue in the area and the attempt is greatly hazardous. Unfortunately, at the present time only surgical exploration allows diagnosis of the anatomic conditions.