Identifier: americanjournroen07ameruoft (find matches)
Title: The American journal of roentgenology, radium therapy and nuclear medicine
Year: 1906 (1900s)
Authors: American Radium Society American Roentgen Ray Society
Subjects: Radiotherapy X-rays
Publisher: Springfield, Ill. C.C. Thomas
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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s made in thesame cycle, one coincident with the onset ofthe first, and the second coincident with theonset of the second sound, give a basis forthe determination of the volume of the heartwhen it contains the greatest and the leastamount of blood, and the difference betweenthese must be the volume of blood pumpedat that beat. This figure, multipled by thenumber of beats per minute, represents theminute volume output of the two ventricles.With a regular heart rhythm, it is surpris- sociated with several lines of study. We wishto report at the present time only certainobservations concerning the change in sizeand shape of the normal human heart duringthe several phases of its cycle, reserving forsubsequent communications observations ofthe cardiac volume output in man and ex-perimental animals under normal and patho-logical conditions. The parts making up theoutline of the .r-ray shadowgraphs of thehuman heart are shown in Fig. i. It is seenthat this outline is made up by all the cham-
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FiG. 2. Electrocardiagram from Lead II, Showing Incident of X-Ray Exposures. ingly easy to make the two exposures at thetime of the two heart sounds by simple man-ual closure of a key while listening to thesounds. It is also possible voluntarily to delayclosure and have the exposure come at othertimes, the incidence in every case beingmarked by the simultaneous electrocardio-graphic record. One gets the swing of therh)^hm while listening and the key closurebecomes a matter of anticipation and not ofreaction. We have also worked with a soundamplifying device which closes the primaryof the A-ray transformer automatically witheach heart sound, but up to the present timewe prefer the manual method because of itssimplicity and selectivity. RESULTS The data that we have obtained up to thepresent time by the use of this method is as- bers of the heart, the left auricle howeverbeing included only to a very limited extent. Studies of the change in the shape of thehuman heart during the various

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