Diagnosis of the Mitral Lesion in Patients with Giant Left Atria.

Aneurysmal dilatation of the left atrium occurs in mitral incompetence (Parsonnet, Bernstein, and Martland, 1946) and in mitral stenosis (Venner, 1954), and its presence may mask the underlying mitral lesion by modifying the left atrial pressure pulse (Fairley, 1961) and the indicator-dilution curve (Nixon and Snow, 1962). The purpose of this communication is to describe the important clinical, haemodynamic, and surgical findings in 19 patients with gross enlargement of the left atrium, and to consider the diagnosis of the underlying mitral lesion.