Precordial movements starting after P and before Q have been studied. Right atrial contraction appears to cause a forward-rightward motion and left atrial contraction a backward movement of the precordium. The latter is exaggerated in most patients with mitral stenosis and in some patients with myocardial failure.STUDY of records of precordial movements of certain patients with cardiac disease has indicated that motions beginning after the P wave and before the Q of the electrocardiogram are sometimes strikingly exaggerated. An understanding of these abnormal motions can only be achieved if one can first interpret the significance of the smaller movements occurring in normal subjects at this time. This communication represents an attempt at such an interpretation. METHODS Ninety-nine subjects were studied. They were divided into 6 groups, as follows: (1) 22 healthy adult males aged 21 to 39; (2) 3 subjects with varying degrees of heart block; (3) 30 patients with mitral stenosis and sinus rhythm; (4) 10 persons with "pure" mitral insufficiency; (5) 7 patients with cor pulmonale; (6) a miscellaneous group of 27 consecutive subjects with sinus rhythm and various other types of acquired cardiac disease.Tracings of precordial motions (kinetocardiograms) were obtained either by the crossbarbellows technic previously described,' or by using a bellows in the center of the funnel, with a terminal cross-sectional diameter of 11 cm. In a few instances a tripod was used rather than the funnel. The results obtained by the different technics were similar. All recordings were made with a 4-channel Sanborn Direct Writer, the electrocardiogram and carotid pulse curves being used for reference.Most of the traces were taken while the breath was held at the end of normal expiration. In labeling the tracings the letter K indicates "kinetocardiogram;" the first numeral in the subscript refers to the V position, and the second to the interspace. Thus K14 is the record from the right parasternal line in the fourth interspace, K45 the left midelavicular line in the fifth interspace, etc.In the analysis of the records a movement was considered to be of atrial origin only if it started after the onset of the P wave of the electrocardiogram, and either before or within .02 second after the start of the QRS complex. In subjects with rapid heart rates there were often large waves just prior to the P wave, which were probably related to passive ventricular filling (fig. 1B). Individuals with slow rates often displayed very small motions before the P wave, the cause of these being unknown.The directions of movement were studied, an upstroke representing an outward motion and a downstroke an inward motion. The time of onset of a given movement in relation to the beginning of the P wave was measured. Since we have no entirely satisfactory method of calibrating the absolute magnitude of precordial movements, as yet, only relative magnitude could be studied. Such relative magnitudes were expressed as the number of millimeters deflection of a give...
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