Cardiac function after embolization of coronaries with microspheres

Radioactive microspheres were injected into the coronary systems of 11 dogs, and the quantity of microspheres entering and remaining in the coronary system was determined by radioactive counting techniques. After progressive injection of small quantities of microspheres over a period of 2–3 hr, leading finally to death by cardiac failure, the total volume of microspheres remaining in the coronary system averaged only 6.5 mm 3 . The pumping ability of the heart at different degrees of embolization was measured by determining successive cardiac function curves, both cardiac output curves and left ventricular minute work curves. In each experiment, both the maximum cardiac output and maximum minute work output decreased approximately proportionately after each individual injection of incremental quantities of microspheres, illustrating that the functional ability of the heart can be expressed very well by the maximum level of these function curves. In all experiments, the cardiac function curves began to deteriorate spontaneously after injection of a very critical quantity of microspheres, and a vicious cycle of deterioration occurred thereafter, resulting in rapid demise of the animal.