Abstract
Intracardiac injections of dyes and of India ink in living cats, rabbits and rats have resulted in complete filling of the capillaries of these hearts. Numerous counts have shown approximately 1100 capillaries to each thousand muscle fibers, or about one capillary to each muscle fiber. But when for any reason the heart dilated during the injection, very few of the capillaries were injected, though the larger vessels were completely injected.
The same results were obtained when human hearts were injected through the coronary arteries. Distension of the chambers prevented injection of the capillaries, but when steps were taken to prevent dilatation of the chambers complete injections were obtained.
At the same time it was noted that perfusion of the coronary arteries in dead hearts resulted in distension of the chambers, and when the walls were so stretched 80 per cent to 90 per cent of the perfusate escaped directly into the chambers of the heart, while only 10 per cent to 20 per cent returned by way of the coronary sinus and veins. These findings suggest that during dilatation of the heart the chief route of blood flow is through the arteries to the Thebesian vessels and thence into the chambers of the heart.
A modification of the Langendorff method of coronary perfusion has given complete injections of the capillaries in cat and rabbit hearts when the hearts were beating strongly. This method when applied to human hearts obtained within three or four hours post mortem has given complete injection of the capillaries in certain areas of the heart. There is approximately one capillary per muscle fiber in the human heart, except in the auricle where the number is not constant and the supply less abundant.
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