The atrial border electrokymogram in mitral regurgitation.

Border electrokymograms of the cardiovascular silhouette in various views were obtained at approximately 1.0 cm. intervals in 28 subjects to determine the constancy and the specificity of the atrial border motion and to determine its ability to differentiate organic from functional apical systolic murmurs. Although a "plateau" curve previously reported as pathognomonic of organic mitral regurgitation was obtained in 12 of the 13 individuals with various types of heart disease and with an apical systolic murmur, identical "plateau" curves were obtained in 10 of the 15 individuals with normal hearts and with no apical systolic murmur. Atrial curves previously reported as normal were also obtained in each of the 28 subjects studied. Some of the reasons for these results, which are at variance with those reported by others, are discussed.