The Coronary Circulation in Cyanotic Congenital Heart Disease

摘要

Background: The coronary circulation in cyanotic congenital heart disease (CCHD) encompasses extramuralncoronary arteries, basal coronary blood flow, flow reserve, the coronary microcirculation, and coronary atherogenesis.nMethods: Coronary arteriograms were analyzed in 59 adults with CCHD. Dilated extramural coronaries were examinednhistologically in 6 patients. Basal coronary blood flow was determined with N-13 positron emission tomography in 14 patientsnand in 10 controls. Hyperemic flow was induced by intravenous dipyridamole pharmacologic stress. Immunostainingnof coronary arterioles against SM alpha-actin permitted microcirculatory morphometric analysis. Non-fasting totalncholesterols were retrieved in 279 patients in four categories: Group A—143 cyanotic unoperated, Group B—47 acyanoticnafter reparative surgery, Group C---41 acyanotic unoperated, Group D---48 acyanotic before and after operation.nResults: Extramural coronary arteries were mildly or moderately dilated to ectatic in 49/59 angiograms. Histologic examinationndisclosed loss of medial smooth muscle, increased medial collagen, and duplication of internal elastic lamina. Basalncoronary flow was appreciably increased. Hyperemic flow was comparable to controls. Alterations in coronary arteriolarnlength, volume and surface densities indicated remodeling of the microcirculation. Coronary Atherosclerosis was not detectednin the either arteriograms or necropsy specimens.nConclusions: Extramural coronary arteries dilate in CCHD in response to endothelial vasodilator substances coupled withnmural attenuation caused by medial abnormalities. Basal coronary flow was appreciably increased, but hyperemic flownwas normal. Remodeling of the microcirculation was the key mechanism for preservation of flow reserve. The coronariesnwere atheroma-free because of hypocholesterolemia, hypoxemia, upregulated nitric oxide, low platelet counts, and hyperbilirubinrmia.