The effect of chronic severe anemia upon functional interarterial coronary anastomoses has been studied in dogs. Retrograde flow measurements at controlled aortic pressures and under conditions of normal viscosity and hemoglobin concentration indicate that severe chronic anemia stimulates growth of collaterals to a significant degree. On the other hand, removal of this stimulus by spontaneous recovery from anemia induces regression of collateral function to control levels. tBUNDAJMT

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... indicate the importance of interarterial coronary anastomoses. When functionally adequate, these channels occasionally allow the occurrence of complete coronary occlusion without the usual clinical symptoms or pathologic changes in the myocardium. 1 It is probable that lesser degrees of collateral function are responsible for the far lower mortality in human beings following coronary occlusion and myocardial infarction than is found in dogs subsequent to coronary ligation. Nevertheless, even the first coronary occlusion, if it does not lead to death, usually exacts a toll of functioning cardiac muscle. Simple measures which induce collateral formation in relatively normal individuals would effect lower mortalities as well as smaller degrees of infarction secondary to a first coronary occlusion. Such a measure would undoubtedly prolong the life, add to the comfort and productive ability of those who are destined to develop severe widespread coronary disease.