MYOCARDIAL PERFUSION COMPENSATES FOR INCREASED CARDIAC WORKLOAD DURING PHENYLEPHRINE, MAINTAINING OXYGENATION

Abstract

s S75 phenylephrine (16-660mg/min, a1-agonist). By deep anaesthesia and Urapidil (a1-blockade), lower blood pressures were achieved. In a 3T MRI scanner, OS-images were acquired at 10-15mmHg increments in a mid left ventricular short axis slice and changes in signal intensity (SI) and myocardial flow response were expressed as %-change 70mmHg baseline. At each level, coronary blood flow was obtained and changes in O2er (D) were calculated (1⁄4100*[CaO2-CvO2/CaO2]), comparing the changes to the oxygenation response. RESULTS: With increasing MAP there was a strong correlation to the LAD blood flow response (red) and a moderate correlation to changes in myocardial oxygenation represented by signal intensity (blue). There was a weak correlation between myocardial OS-SI and flow response changes. Interestingly, there was a weak negative correlation between MAP and O2er changes (green), indicating that during the MAP increase there was a luxury perfusion that exceeded the myocardial oxygen demand, allowing OS-SI to increase, while O2er dropped. This was confirmed by the negative correlation of O2er with OS-SI and flow response. RPP showed the same trend as MAP (table) to flow and O2er, yet no relationship was found to SI. CONCLUSION: a1-mediated blood pressure changes induced by phenylephrine result in a luxury perfusion paralleled by an increase in myocardial oxygenation, despite increased myocardial workload. Oxygenation-sensitive cardiovascular magnetic resonance is a suitable tool to monitor the effects of vasopressors on myocardial oxygenation. Research in Anaesthesiology and Intensive Care Medicine, Inselspital Bern University Hospital 147 SURGICAL APPLICATION OF A NOVEL BIOMATERIAL ATTENUATES POST-MI REMODELING AND HEART FAILURE: IMPACT OF INTERVENTION TIMING RELATIVE TO INFARCT STAGE ON FUNCTIONAL RECOVERY HE Mewhort, JD Turnbull, G Teng, DD Belke, DA Svystonyuk, DG Guzzardi, HJ Duff, PW Fedak