Movements and Forces of the Human Heart

Abstract

The present study is one in a series designed to elucidate the genesis of the precordial motions. It is concerned with an attempt to learn whether low-frequency precordial tracings (kinetocardiograms [KCG]) can be utilized as an index to the time of onset of ejection and filling.A number of observers have published data concerning the time elapsing between the beginning of electrical excitation and the start of the pressure rise in the pulmonary artery and the aorta.1-3 These studies indicate that the right and left ventricles begin to eject at approximately 0.08 and 0.10 second, respectively, after the onset of the QRS. Similar studies indicate that ventricular filling begins about 0.10 second after the beginning of the second heart sound.2 Consequently, this study is concerned with precordial motions occurring at these particular times, in the hope that such events may afford information which can be readily and simply obtained and which will furnish a guide as to the time of onset of ejection and filling of the ventricles. MethodsThe subjects studied were 36 men who lacked evidence of cardiac disease. Of these, 25 were in the third decade; 6, in the fourth, and 5, in the sixth or seventh.Records were made from various interspaces in the right and left parasternal regions, in the left midclavicular line, in the area of the apex, and also from the right and left epigastric regions. Two techniques were used for recording the precordial tracings. One of them was the crossbarbellows method described in previous communica¬ tions.t_e The other involved the use of a funnel 11 cm. in its largest circumference, which was strapped to the chest. In the center of the funnel was a small bellows, motion of which was activated by a metal probe 3 mm. in diameter, which was placed in an intercostal space at the desired point. The results obtained by the two procedures were similar except in regard to some minor details, which will be mentioned later.As reference tracings, the electrocardiogram and the carotid pulse were utilized.For convenience of description, the various precordial points are designated as follows : The letter is used to denote the kinetocardiogram, and numerals are utilized to indicate the transverse and vertical positions-one meaning right parasternal, two meaning left parasternal, and four meaning left midclavicular. Thus the first, or left, numeral has the same significance as that in the V leads of the electrocardiogram. The second, or right, numeral refers to the interspace. Thus K13 represents the kinetocardiogram obtained from the third interspace in the right parasternal line; K15, that obtained from the fifth interspace in the left midclavicular line, etc. The terms Ker, Km., and Kx refer, respectively, to traces from the right and left epigastric regions and from the point of maximal impulse. Thus in stocky subjects with transverse hearts, the Kx point might correspond to K45 or even Ku, while in slender persons with vertical hearts the Kx point would tend to be K35 (i. e., the fifth interspace midw...