Electrokymography: I. The ventricular electrokymogram

Abstract

In this review application of the electrokymographic method to the study of left ventricular border motion is discussed. The method has obvious limitations, principally because true volumetric curves are not obtained due to superimposed positional changes. It is necessary, therefore, to be cautious in interpreting the graphs and to become acquainted with the normal variations encountered. Nevertheless, continued experience with the method indicates that characteristic patterns may be evolved in normal and abnormal states. From a physiologic standpoint the electrokymogram has been helpful in a better understanding of the events in the cardiac cycle. Demarcation of the various phases of mechanical systole and diastole has been aided immeasurably by simultaneous recordings with several graphic methods. It has thus been possible to study each phase of the cycle and integrate it with the serrations recorded in the electrokymogram. It is hoped that continued study along these lines will shed considerable light upon the less clearly understood phases, particularly isometric contraction and relaxation. Studies are already beginning to appear on the effect of drugs such as digitalis on the mechanical behavior of the myocardium. Clinically, the ventricular electrokymogram appears to be most useful in the detection of impaired myocardial action consequent to myocardial infarction and localized damage due to various pathologic states. Although the electrokymograph is by no means the simplest or most useful method for the determination of myocardial damage, we have encountered specific cases in which it has been most helpful. This applies particularly to cases of myocardial infarction associated with bundle branch block or doubtful electrocardiographic findings, or cases in which the electrocardiogram has returned to normal. In these instances unequivocal electrokymographic findings established the diagnosis. Evidence is presented that the ventricular electrokymogram may yield valuable information concerning myocardial aberration in conditions such as hypertensive heart disease, coronary sclerosis, constrictive pericarditis, myasthenia gravis and congenital heart disease. Involvement of the entire heart in pulsus alternans is clearly demonstrated. In a subsequent review we shall discuss the findings in disturbances affecting the atria and great vessels, cardiac arrhythmias, ventricular asynchronism and valvular heart disease.