Myocardial tissue oxygen supply and utilization during coronary artery bypass surgery: evidence of microvascular no-reflow

Abstract

The supply and utilization of oxygen by the myocardium reflect the dynamic efficiency of the microcirculation. The present study examines these parameters during coronary artery bypass surgery. We used a voltammetric microelectrode technique to assess regional variations in myocardial tissue partial pressure of oxygen (PO(2)) and myocardial tissue perfusion (MTP) in patients undergoing coronary artery bypass surgery. A total of 29 myocardial regions were studied in 17 patients to assay tissue PO(2), and 13 regions in 10 patients to measure MTP. There was an increase in MTP from 53+/-9 ml.min(-1).100 g(-1) before cardiopulmonary bypass to 72+/-13 ml. min(-1).100 g(-1) after (means+/-S.E.M.; P=0.05). Tissue PO(2) showed an overall increase from a baseline level of 45+/-8 mmHg to a final level of 88+/-10 mmHg (P<0.0001). Following release of the aortic cross-clamp there was a variable time delay before a change in tissue PO(2) was observed. There was an immediate response in five regions, whereas in 20 regions the response was delayed by between 0.5 and 32 min. In the remaining four regions there was no change in tissue PO(2). The duration of the delay in response was correlated positively with the cross-clamp time (r=0.45, P<0.05) and negatively with the final tissue PO(2) (r=-0.5, P<0.05). Voltammetric methods for monitoring changes in oxygen supply and utilization offer new insights into the changes that occur during ischaemia and reperfusion. A delay in the delivery of oxygen to the myocardium occurs in many patients following coronary artery bypass surgery.

Right ventricular myocardial oxygen tension is reduced in monocrotaline-induced pulmonary hypertension in the rat and restored by myo-inositol trispyrophosphate

“…Here we showed that RV pO 2 was more than twofold higher than LV pO 2 (32 ± 5 mmHg and 15 ± 8 mmHg, respectively) in control rats. These values for LV are within the ranges reported by other authors and obtained using different methods: 45 mmHg in the LV of humans undergoing bypass surgery using voltammetric microelectrode technique 19 , 35 mmHg of mitochondrial O 2 in the rat LV 20 , 10 mmHg in the rat LV 21 and 8.6 mmHg in the swine LV using electron paramagnetic resonance oximetry 22 . These results indicate that LV pO 2 values in the literature vary considerably and are probably method-dependent.…”

Right Ventricular Myocardial Oxygen Partial Pressure Is Reduced in Monocrotaline-induced Pulmonary Hypertension in the Rat and Restored by Myo-inositol Trispyrophosphate

“…Here we showed that RV pO 2 was more than 2-fold higher than LV pO 2 (32±5 mmHg and 15±8 mmHg, respectively) in control rats. These values for LV are within the ranges reported by other authors and obtained using different methods: 45 mmHg in the LV of humans undergoing bypass surgery using voltammetric microelectrode technique [19], 35 mmHg of mitochondrial O 2 in the rat LV [20], 10 mmHg in the rat LV [21] and 8.6 mmHg in the swine LV using electron paramagnetic resonance oximetry [22]. These results indicate that LV pO 2 values in the literature vary considerably and are probably method-dependent.…”

CT imaging of myocardial scars with collagen-targeting gold nanoparticles

“…1 However, in a subset of patients with viable myocardial tissues in the peri-infarct zone, studies have clearly shown that revascularization procedures such as coronary artery bypass grafts and coronary angioplasty increase left ventricular ejection fractions and improve survival in those patients. 2,3 Clearly, identification of such patients will be important for disease management.…”