Abstract
The effect of chronic coronary arterial narrowing on the coronary collateral circulation has been studied in rested and exercised dogs. The data indicate that moderate and severe arterial narrowing results in extensive collateral development proportional to the degree of narrowing, further that exercise leads to even greater anastomoses. The results also show that while mild arterial narlowing fails to initiate collateral growth by itself, the addition of exercise promotes an effective collateral circulation. An attempt is made to define the gross factors in the development of collateral vessels and to correlate them with the concept that exercise may play a beneficial role in building collateral vessels in patients with coronary disease.