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Acute coronary occlusion: Early changes that induce coronary dilatation and the development of collateral circulation∗

1969; Elsevier BV; Volume: 24; Issue: 6 Linguagem: Inglês

10.1016/0002-9149(69)90466-4

1879-1913

Robert M. Berne, Rafael Rubio,

Cardiac Ischemia and Reperfusion

Coronary occlusion initiates several chemical changes capable of producing arteriolar dilatation. The most important of these are a reduction in pO2, an increase in pCO2 and increases in the concentrations of lactic acid, potassium and adenosine in the interstitial fluid of the myocardium. Of these factors, only adenosine can account for the entire coronary dilatation observed in myocardial ischemia. However, the other factors probably contribute to the relaxation of the vascular smooth muscle. The strongest stimulus for the development of coronary collateral vessels is coronary arterial narrowing, although evidence suggests that hypoxia alone will result in moderate enhancement of collateral circulation. Of the various surgical procedures employed to increase collateral vessel development, the only one that shows promise is implantation of the open internal mammary artery into the myocardium. In experimental coronary arterial constriction the peripheral coronary arterial pressure (pressure distal to the point of constriction) appears to be a good index of collateral vessel development. Intercoronary collateral vessels are insensitive to almost all vasoactive agents, but recent data indicate that the beneficial effects of nitroglycerin in angina pectoris may be due to a selective vasodilator action on well developed collateral arteries.