[Coronary and renal circulation in patients with cardiac failure after converting enzyme inhibitors].
The cardiac output and its peripheral distribution must fulfill the metabolic and/or functional requirements of the different organs. The various techniques used to measure blood flow rates in the coronary and renal arteries provide much information on this point, but they do not tell us all we would like to know about the distribution and "utilization" of these flows in tissues. In normal subjects the myocardial oxygen consumption is not markedly different from the renal oxygen consumption, but the mechanisms that regulate the coronary and renal circulations are not the same. The flow rate in the coronary vessels is about 10% of the cardiac output, the arteriovenous oxygen gradient is superior to 10 vol % and regulation is metabolic. In the renal vessels, which are primarily "functional", the flow rate is about 25% of the cardiac output and the arteriovenous oxygen gradient is inferior to 2 vol %. In heart failure patients, despite reduced cardiac output the blood pressure is kept normal for a long time by vasoconstriction of the arterioles, a process which involves, at least partly, the renin-angiotensin system. The vasoconstriction predominates in some circuits (the renal flow rate is less than 15% of the cardiac output) and spares the "privileged" circuits (the coronary flow rate is more than 15% of the cardiac output). Under the influence of angiotensin converting enzyme inhibitors, the cardiac output increases and its distribution is modified. The coronary flow rate remains stable or is reduced in proportion to the decrease in myocardial oxygen consumption, the metabolic regulation is preserved and there is no "coronary steal". The percent increase in renal flow rate is usually superior to that of the cardiac output. This peripheral redistribution of coronary and renal blood flow rates in heart failure patients after treatment with converting enzyme inhibitors seems to correspond to the physiological purposes of the two regional blood flows.
D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril / Q000627:therapeutic use; D002302:Cardiac Output / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D004656:Enalapril / Q000627:therapeutic use*; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects*; D012084:Renin-Angiotensin System / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D000806:Angiotensin-Converting Enzyme Inhibitors; D004656:Enalapril; D002216:Captopril
Circulations coronaire et rénale chez des malades en insuffisance cardiaque après inhibiteurs de l'enzyme de conversion.