Myocardial blood flow and oxygen consumption in man early after valve replacement

Lactate Elevation During and After Major Cardiac Surgery in Adults: A Review of Etiology, Prognostic Value, and Management

Elevated lactate is a common occurrence after cardiac surgery. This review summarizes the literature on the complex etiology of lactate elevation during and after cardiac surgery, including considerations of oxygen delivery, oxygen utilization, increased metabolism, lactate clearance, medications and fluids, and postoperative complications. Second, the association between lactate and a variety of outcomes are described, and the prognostic role of lactate is critically assessed. Despite the fact that elevated lactate is strongly associated with many important outcomes, including postoperative complications, length of stay, and mortality, little is known about the optimal management of postoperative patients with lactate elevations. This review ends with an assessment of the limited literature on this subject.

Coronary sinus blood flow at rest and during isometric exercise in patients with aortic valve disease. Mechanism of angina pectoris in presence of normal coronary arteries

In 46 patients with aortic valve disease, coronary sinus blood flow was measured using a continuous thermodilution method both at rest and during isometric handgrip exercise. All patients had normal coronary angiograms. The patients were separated into three groups: Group I, 12 patients with aortic stenosis (systolic gradient 72 +/- 12 mm Hg); Group II, 15 patients with both aortic stenosis and regurgitation; Group III, 19 patients with aortic regurgitation. At rest, the coronary sinus blood flow was two to three times normal. However, when corrected for left ventricular mass (ml/100 g), flow was within normal limits. The ratio diastolic pressure-time index/systolic pressure-time index (DPTI/SPTI) was decreased in all three groups at rest. During isometric exercise, coronary sinus blood flow increased significantly: by 60 percent in Group I, by 88 percent in Group II and by 118 percent in Group III. There was a significant reduction of the DPTI/SPTI ratio. Of the 18 patients with angina on effort during the test, 7 were in Group I, 6 in Group II and 5 in Group III. There were no differences in the coronary sinus blood flow between the patients with angina and those who were pain-free, either at rest or during exercise. Angina pectoris does not appear to be caused by a failure of coronary blood flow to increase. There was no discrepancy between myocardial demand, as measured by the pressure-time index and coronary blood flow. However, the DPTI/SPTI ratio was significantly lower during exercise in the patients with angina than in those who were pain-free. Underperfusion of the subendocardial muscle seems to be a causative factor in the patients with angina.