THE CAPACITY OF THE CORONARY BED IN CARDIAC HYPERTROPHY.

After eliminating vascular rigor, perfusing human hearts with kerosene under pressure postmortem gives values for coronary flow which seem an index of the maximum possible flow during life. This is 3.1 cc. per gm. per minute at 100 mm. Hg in normal men under 40. It is 35 per cent lower in the hearts of those 60 to 80 years old, and also falls in hypertrophied hearts. In old people it is 30 per cent lower in hearts over 600 gm. than in those under 350; in patients 40 to 60 years old it is 37 per cent less in hearts over 600 as compared with those under 350 gm. In discussion it is brought out that while the decrease in coronary capacity associated with age or hypertrophy may play a part in predisposing some hearts to congestive failure, there is no evidence that the hypertrophied heart has an inadequate oxygen supply or that its fibers are too thick for adequate oxygen diffusion. Congestive failure cannot be ascribed to anoxia except in the presence of severe anemia, coronary occlusion, or tachycardia with low blood pressure. Decrease in perfusibility with age and growth may be a perfectly normal adaptation to the needs of the tissue; the perfusibility of the heart of the young adult is about half that of an infant at 2 years.