Abstract
Certain problems of cardiodynamics can be studied profitably by the use of an improved isolated mammalian heart preparation. The mode of relaxation of the ventricle, for example, may hold further information concerning the control of cardiac output, for it is increasingly apparent that the remarkable property of the heart is not only that it can pump so much, but also that it can fill so efficiently. A study of the relaxation process of the ventricle is difficult, however, when large volumes of blood are being pumped by the heart.
In order to study the relaxation process adequately an isolated heart preparation should possess the following attributes: (a) generate ventricular pressure pulses of normal contour, (b) possess easy control of atrial and ventricular systolic and diastolic pressures, (c) pump no blood, i.e., have a fixed ventricular volume, and (d) not deteriorate over a period of many hours. The preparation to be described possesses all these characteristics to a satisfactory extent.
The preparation. Heyman and Kochman ( 1 ) apparently introduced the idea of using a donor dog to supply the blood and pressure head for the perfusion of the coronary arteries of the isolated heart. Although their method has not been used extensively it has an advantage over the use of mechanical perfusion systems, namely, that the presence of the intact lungs, liver and kidney of the donor dog can maintain a more normal blood chemistry.
Fig. 1 shows the schema currently used. Blood from the femoral artery of the donor dog enters and ascending aorta via a cannula (A) introduced through a common carotid artery. The aorta is tightly ligatured at the arch (B), as are all head vessels (C) and the left subclavian artery (D).
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