. Elements of human physiology. Physiology. 220 PHYSIOLOGY chest-wall in immediate proximity to the ventricles, and so gives rise to the ' apex-beat.' The cardiac impulse may be registered by means of a cardiograph. In nearly all forms of this instrument a button, resting on the chest-wall, transmits the movements of the latter to a tambour, which again is connected by a tube to a registering tambour. One such instrument is shown in Fig. 117. The curves so obtained, which are known as cardiograms, may vary considerably in the same subject according to the pressure employed and the exact spot a
. Elements of human physiology. Physiology. 220 PHYSIOLOGY chest-wall in immediate proximity to the ventricles, and so gives rise to the ' apex-beat.' The cardiac impulse may be registered by means of a cardiograph. In nearly all forms of this instrument a button, resting on the chest-wall, transmits the movements of the latter to a tambour, which again is connected by a tube to a registering tambour. One such instrument is shown in Fig. 117. The curves so obtained, which are known as cardiograms, may vary considerably in the same subject according to the pressure employed and the exact spot at which the tambour Fig. A cardiograph. This is strapped round the chest, the central button is applied to the ' apex-beat' and its pressure on the chest-wall regulated by means of the three screws at the sides. The tube at the upper part of the instrument serves to connect the drum of the cardiograph with a registering tambour such as that shown in Fig. 113. is applied. Their interpretation often presents considerable difficulties, owing to the fact that their form is conditioned by two factors, viz. : (1) The actual size (antero-pogterior diameter) of the ventricles. (2) The resistance to distortion { the tension) of the ventricular wall. This factor will increase in importance with increasing pressure of the cardiograph button on the chest wall. Fig. 118 represents a cardiographic tracing or cardiogram, which may be spoken of as typical. In order to interpret this curve, we must record at the same time either the intra-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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