[Effects of fentanyl on left ventricular diastolic function]

Effects of fentanyl on left ventricular diastolic function were investigated in chronically instrumented dogs. An electromagnetic mitral flow probe was placed in the left atrium and a micromanometer was placed in the left atrium as well as in the left ventricle to measure ventricular pressure (LVP), left atrial pressure (LAP), derivative of left ventricular pressure (dp/dt), mitral flow (MIF) and ECG in conscious resting dogs. Following induction of anesthesia with thiopental (15-20 mg.kg-1) and vecuronium (0.1 mg.kg-1), fentanyl (10, 50 and 100 mcg.kg-1) was administered at 30 min intervals. The direct measurement of phasic MIF was used to obtain a set of diastolic indices: peak rapid filling period (PRFR), filling volume (FV), FV due to atrial contraction (FV-A), isovolumic relaxation period (IVRP) and diastolic filling period (DFP). Each diastolic index during conscious resting state was compared with that obtained during fentanyl anesthesia using paired t-test. There were no significant changes in those diastolic indices under fentanyl (10, 50 and 100 mcg.kg-1) anesthesia except PRFR and dp/dt under fentanyl 10 mcg.kg-1 which decreased. Although heart rate decreased about 50% under fentanyl, IVRP and PRFR did not increase significantly, but DFP (P less than 0.05) and FV (P less than 0.01) increased significantly. DFP correlated well with RR interval under conscious resting state under fentanyl anesthesia (r = 0.992 and r = 0.967). This study suggests that in the absence of surgical stress, fentanyl does not impair left ventricular diastolic function.