. Diseases of the heart and thoracic aorta. reater part, or even the whole of theanterior surface of the heart, is overlapped, and its impulsetherefore obscured. ANALYSIS OF A CARDIOGRAPHIC TRACING. The analysis of cardiographic tracings is attended withgreat difficulties, and some important points are not yetclearly understood. The conclusions, which have beenarrived at, have been partly drawn from observation (such asthose of Chauveau and Marey) made by recording the pres-sure within the cardiac cavities of the lower animals, thehorse ; partly from tracings taken from the exposed hearts
. Diseases of the heart and thoracic aorta. reater part, or even the whole of theanterior surface of the heart, is overlapped, and its impulsetherefore obscured. ANALYSIS OF A CARDIOGRAPHIC TRACING. The analysis of cardiographic tracings is attended withgreat difficulties, and some important points are not yetclearly understood. The conclusions, which have beenarrived at, have been partly drawn from observation (such asthose of Chauveau and Marey) made by recording the pres-sure within the cardiac cavities of the lower animals, thehorse ; partly from tracings taken from the exposed hearts ofthe lower animals, the button of the tambour being in directcontact with the exterior of the ventricles ; and partly fromcardiographic tracings taken from the cardiac impulse as felton the chest wall of men. A cardiographic tracing consists of a series of curves(see fig. 301), each one of which corresponds to a completecardiac revolution, the time which elapses from the com-mencement of one ventricular systole to the termination of. Fig. 301. Normal Cardiographic tracing.—{After Galahin.) the ventricular diastole. Each individual cardiac curve (seefig. 302 A to B) is composed of two portions, i and 2, whichrepresent the systole and diastole of the ventricles respec-tively ; and since cardiographic tracings in man are usually 76o Appendix. taken from the left apex-beat, it is the systole and diastoleof the left ventricle which is most accurately the following description I shall then, for the sake of sim-plicity, limit my remarks to the left heart.^
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectheart, bookyear1884
