Heart-Lung Preparation

in experimental physiology, a warm-blooded animal used in studies of isolated heart function. I. P. Pavlov and N. Ia. Chistovich introduced the first heart-lung preparation in 1887, and an improved, more complex heart-lung preparation was developed by E. Starling between 1912and 1918.

In experiments on a heart-lung preparation the heart remains in the animal’s thoracic cavity, and coronary circulation and artificial pulmonary ventilation are maintained. As a result, pulmonary circulation continues normally, and blood becomes oxygenated in the lungs and releases carbon dioxide. Systemic circulation is excluded by the ligation of the aorta and venae cavae by means of cannulas. The cannulas are connected to an artificial system of tubes and reservoirs that replaces systemic circulation, providing for the pumping of blood from the left ventricle into the aorta and subsequently into the venae cavae, right auricle, and right ventricle.

Resistance in the artificially created system may be altered, thereby simulating the level of arterial resistance and the flow of venous blood to the heart. Studies conducted with a heart-lung preparation make it possible to investigate the dependence of heart function on systemic resistance and on the volume of blood flowing to the heart; a better understanding of the mechanism regulating the pumping action of the heart is also provided. In a standard heart-lung preparation, the heart is deprived of the effect of extracardiac nerves. There are various modifications of the heart-lung preparation, some of which retain the effect of extracardiac nerves on the heart.