title: [Dependence of blood flow in human aorto-coronary bypass grafts on the extravascular resistance (author's transl)].
abstract: As has been shown in a large number of animal experiments, there is a marked difference between the systolic-to-diastolic flow ratios of the right coronary artery and the left. We examined these ratios in 107 patients who were undergoing aorto-coronary bypass surgery as treatment for coronary artery disease. After cessation of cardio-pulmonary bypass, the blood flow was recorded electromagnetically in a total of 126 venous grafts to the right or to the branches of the left coronary arteries. From these tracings, the following magnitudes were calculated: coronary stroke flow per heart beat, systolic and diastolic stroke flows, mean flow, systolic and diastolic flows. The ratio of the systolic to the diastolic stroke flow was 0.30 +/- 0.17 for the branches of the left coronary artery (n = 79) and 0.61 +/- 0.30 for the right coronary artery (n = 47). The ratio of systolic to diastolic flow was found to be 0.46 +/- 0.25 (branches of the left coronary artery) and 1.01 +/- 0.62 (right coronary artery), respectively. All these values differ statistically on a probability level of p less than 0.001. In principle, our results agree with those of canine experiments. The considerable variation of the individual values of the systolic-to-diastolic flow ratios can be explained by the following: 1. the variability of the pattern of coronary blood supply in man; 2. the actual right and left ventricular pressures; 3. the extent of stenoses present; 4. the degree of myocardial impairment due to ischemia. These factors combined determine the actual value of the extravascular (myocardial) component of the peripheral coronary resistance, which is most effective during systole.
mesh_terms: D001783:Blood Flow Velocity; D001026:Coronary Artery Bypass; D003326:Coronary Circulation; D003327:Coronary Disease / Q000601:surgery; D004562:Electrocardiography; D006801:Humans; D008433:Mathematics; D011674:Pulse
vernacular_title: Abhängigkeit der Strömung im aorto-koronaren Bypass des Menschen vom extravasalen Widerstand.