ATRIAL SEPTAL DEFECT

Abstract

Atrial septal defect is one of the common types of congenital heart disease.Although recognized for centuries and receiving increasing attention since 1900, it was the detailed description by Bedford, Papp, and Parkinson in 1941, of the physical, electrocardiographic, radiological, and diagnostic features, the complications, and the clinical course, that brought the salient characteristics of this disorder to the attention of the medical profession.More recently, with the advent of new tech- niques of investigation, many publications have described the pathological physiology of the disease (Howarth et al., 1947; Barber et al., 1950; Lequime et al., 1950; Soulie et al., 1950; Puddu, 1952; Limon Lason et al., 1953; Heim de Balzac et al., 1954).Finally, the introduction of surgical correction has given impetus to further inquiries into its many facets.As Bedford, Papp, and Parkinson pointed out, there are a number of complications that occur and lead to varying degrees of incapacity-complications that may well have an important bearing on the risk of surgical intervention.It seems timely, therefore, to inquire further into the nature of this disorder and some of its complications-(1) hypoxemia giving rise to cyanosis, (2) pul- monary vascular disease, (3) right ventricular failure, (4) left ventricular failure, and (5) mitral stenosis or Lutembacher's syndrome. MATERIALSixty patients have been studied by cardiac catheterization, as described elsewhere (Dexter et al., 1947).Seven of these patients were studied twice.There were 42 females and 18 -males, ranging in age from 3 to 57 years.Calculations of blood flow in patients with atrial septal defect are fraught with error.The narrow arteriovenous oxygen difference between pulmonary vein and artery associated with large pulmonary blood flows seriously interferes with the accuracy of the calculation by the Fick method.One may, in fact, be confronted with the distressing circumstances of having an arteriovenous oxygen difference so narrow as to be undetected by Van Slyke oxygen analysis, thus resulting in the calculation of an infinite pulmonary blood flow.There is no adequate site for obtaining mixed venous blood for the calculation of left ventricular cardiac output.We have used the superior vena cava.Errors involved in the calculation of ventricular outputs and shunts have been described in some detail (Dexter et al., 1947).These errors, however, do not detract from the usefulness of such measurements because they reflect large, medium, or normal right ventricular outputs; large, medium, or small left-to-right shunts; left ventricular outputs that at least are not raised and are in all probability subnormal; and right-to-left shunts that are small.The associated calculations of work and resistances necessarily suffer from the lack of precision of flow measurements, but it is believed that they are of similar value.