Abstract This study was performed to assess the relationship between coronary sinus blood flow (by thermodilution) and myocardial oxygen demand (heart rate‐systolic arterial pressure double product) during atrial pacing in patients with and without coronary artery disease. In 11 individuals with coronary artery disease, pacing was performed to ischemia, as reflected by electrocardiographic changes or lactate production; 8 patients without coronary artery disease served as controls. Coronary sinus blood flow (in ml/min) was similar for the two groups at rest. However, the increase in coronary blood flow from rest to peak pacing was less (P = 0.025) in those with coronary artery disease (50 ± 26 ml/min) than in controls (79 ± 26 ml/min). The ratio of coronary sinus blood flow to double product was the same at rest in both groups (11.1 ± 2.2 × 10 −3 controls, 11.6 ± 2.7 × 10 −3 coronary artery disease; NS). At peak pacing, it was unchanged in the controls (10.4 ± 2.0 × 10 −3 ) but fell in those with coronary artery disease (9.0 ± 2.5 × 10 −3 ; P = 0.002). The aortic‐coronary sinus oxygen content difference was similar at rest in both groups and did not change in response to pacing in either group. Thus, in response to augmented myocardial oxygen demand, patients without coronary artery disease have an appropriate increase in coronary blood flow and myocardial oxygen supply, while in those with coronary artery disease who develop ischemia the increment in myocardial blood flow (and oxygen supply) is inappropriately low.
In patients who have myocardial infarction with ST-segment elevation, rupture of an atherosclerotic plaque leads to platelet adhesion, activation, and aggregation, with subsequent vessel occlusion due to thrombus formation. In these circumstances, the most effective pharmacologic reperfusion regimen is concurrent fibrinolytic therapy and platelet inhibition. The marked benefit of such a combination was first established in the Second International Study of Infarct Survival, in which 35-day mortality among patients with suspected myocardial infarction was 13.2 percent for those receiving neither streptokinase nor aspirin, approximately 10.5 percent for those given one or the other, and 8.0 percent for those receiving both . . .
Background The noninvasive measurement of absolute epicardial coronary arterial flow and flow reserve would be useful in the evaluation of patients with coronary circulatory disorders. Phase-contrast magnetic resonance imaging (PC-MRI) has been used to measure coronary arterial flow in animals, but its accuracy in humans is unknown. Methods and Results Twelve subjects (7 men, 5 women; age, 44 to 67 years) underwent PC-MRI measurements of flow in the left anterior descending coronary artery or one of its diagonal branches at rest and after administration of adenosine (140 μg·kg −1 ·min −1 IV). Immediately thereafter, intracoronary Doppler velocity (IDV) and flow measurements were made during cardiac catheterization at rest and after intravenous administration of adenosine. For the 12 patients, the correlation between MRI and invasive measurements of coronary arterial flow and coronary arterial flow reserve was excellent: coronary flow MRI (mL/min)= 0.85×coronary flow IDV (mL/min)+17 (mL/min), r =.89, and coronary flow reserve MRI =0.79×coronary velocity reserve IDV +0.34, r =.89. For the range of coronary arterial flows (18 to 161 mL/min) measured by MRI, the limit of agreement between MRI and catheterization measurements of flow was −13±30 mL/min; for the range of coronary reserves (0.7 to 3.7) measured by MRI, the limit of agreement between the two techniques was 0.1±0.4. Conclusions Cine velocity-encoded PC-MRI can noninvasively measure absolute coronary arterial flow in the left anterior descending artery in humans. PC-MRI can detect pharmacologically induced changes in coronary arterial flow and can reliably distinguish between those subjects with normal and abnormal coronary artery flow reserve.
Patients with coronary artery disease face increased risks when they undergo noncardiac surgery. This is attributable to the cardiovascular stress imposed by the surgical procedure and the effects of anesthetic agents on the cardiovascular system. Several approaches to managing patients with coronary artery disease before, during, and after noncardiac surgery include "prophylactic" myocardial revascularization procedures, digitalization, use of propranolol hydrochloride, and insertion of temporary intravenous pacemakers. (Arch Intern Med138:972-975, 1978)
