Electrokymography: II. the great vessel and auricular electrokymograms

Abstract

In these reviews we have attempted to provide a broad and comprehensive picture of the electrokymographic method as applied to normal and abnormal cardiac states. In the previous article 1 we discussed the ventricular border curves. In the present review we have dealt with the movements of the atria and great vessels. We have recorded our own findings and as far as possible have tried to present the views of other workers in the field. The nature of the articles has precluded detailed discussion, which the interested reader will find in papers on specific subjects. At all times we have been careful to point out the limitations of the method and the possibilities for error in interpretation. Over three years of experience has convinced us that study of the mechanical behavior of the cardiac chambers and of the great vessels is of great physiologic interest and may be diagnostic in certain cardiac aberrations. It should be emphasized that many of the recorded findings had already been noted with the roentgenkymograph. However, we believe that the electrokymograph is a greatly superior instrument, chiefly because of its greater sensitivity, ease of exploration of the entire cardiac silhouette and the availability of other graphic methods simultaneously recorded for correlation and analysis. Such simultaneous recordings have been fruitful in the delineation and study of the phases of the cardiac cycle, particularly the isometric periods, despite certain discussed hazards of measurement. The influence of auricular and ventricular contraction on the production of the heart sounds is clearly discernible by this method. Also, the occurrence of ventricular asynchronism may be detected. In our hands, the greatest clinical value of the instrument has been attained in the study of diseases of the myocardium and, more specifically, of myocardial infarction. This has been discussed fully in the previous review. 1 The electrokymographic findings in valvular heart disease are of great physiologic significance. The phenomenon of atrial systolic plateau in mitral and tricuspid regurgitation may become a useful method of evaluating the apical systolic murmur. In congenital heart disease electrokymography promises to be helpful in studying the status of the pulmonary artery circulation, particularly if the instrument is successfully calibrated as now appears to be the case. Investigations now in progress hold great promise that two of the most urgently needed clinical tests of cardiac function may be solved by electrokymography, namely, simple determinations of cardiac output and pulmonary artery pressure. Success in these fields would replace cumbersome, costly and hazardous technics by a relatively simple procedure. In bundle branch block, Wolff-Parkinson-White syndrome and the various cardiac arrhythmias the electrical and mechanical events of the cardiac cycle can be correlated. Observations were presented concerning the relationship between length of diastolic interval, interval between auricular and ventricular systole, the strength and amplitude of cardiac contraction and the intensity of the heart sounds. It was pointed out that the method can be of diagnostic aid in differentiating mediastinal and lung tumors from vascular or cardiac aneurysm. In our opinion, the results presented in these reviews justify further intensive studies with the electrokymograph. Continued study will eventually simplify the instrument, expand its usefulness and provide another valuable aid in the study of cardiac physiology and disease.