Electrokymographic studies of the normal cardiac cycle.

Nornal subjects were studied by employing two electrokymograms simultaneously. By comparing the sequence of events in the carotid pulse, auricle and ventricle, measurements were made of the phases of the cardiac cycle. The normal electrokymogram is discussed and illustrated. Simultaneous electrokvmography of the right-and left-sided chambers and vessels of the heart provides a simple method for comparing synchronicity of events in normal and pathologic states. Data obtained in normal subjects is presented. C ARDIOLOGISTS and physiologists have long sought to develop clinically feasible methods of recording and studying the mechanical and electrical phases of the cardiac cycle in intact man. No one will deny that success has crowned efforts to record the electrical potentials developed in the heart. Recording of peripheral arterial and venous pulsations and heart sounds has also become routine procedure. One of the remaining hurdles has been the recording of the motion of the heart borders. Among the methods used for the latter purpose the roentgenokymogram is the best known. Applications of this method proved to be limited in scope.1-7 In the past two decades various attempts have been made to record the heart border, as seen fluoroscopically, with the aid of a photoelectric tube.8-11 The most successful device currently in use was developed by Henny and Boone.2' "1 This consists of a multiplier photoelectric tube with a fluorescent screen activated by the roentgen rays which have passed through the subject being studied. Filters are employed to remove interference created by the roentgen tube. Henny and Boone employed a simultaneous recording of the carotid pulse as a timing device. Luisada and co-work-published with the approval of the Chief Medical Director. The statements and conclusions published by the authors are the result of their own study and do not necessarily reflect the opinion or policy of the Veterans Administration. 250 ers14 "' have used the heart sounds, while An-dersonl6has resorted to the electrocardiogram. Electrokymography has proved to be of great value. Accurate recording of the motions of the cardiac contour is now possible and studies of the various phases of the cardiac cycle, especially the isometric relaxation phase, have been undertaken.'7"-9 Studies of asynchronous contractions of the auricles and ventricles in normal individuals and in those with bundle branch block have been reported.20 21 Confirmation of assumptions made in the course of these investigations has been achieved by correlation of electrokymographic curves with intra-auricular and intraventricular pressure curves.22 …