title: Effects of thoracic epidural anaesthesia on central haemodynamics compared to cardiac beta adrenoceptor blockade in conscious rats with acute myocardial infarction.
abstract: The study aimed to compare the effects of thoracic epidural anaesthesia (TEA) with those of the beta-adrenoceptor blocker, metoprolol, on central haemodynamics in conscious rats with acute myocardial infarction. During methohexital anaesthesia, appropriate vascular catheters were inserted, a thoracic epidural catheter was implanted and the left coronary artery was ligated. A recovery period of 1-2 h elapsed after termination of surgery and anaesthesia. Experiments were performed on four separate groups of animals (A-D). In Group A (n = 10) mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO) were measured, and stroke volume (SV) and systemic vascular resistance (SVR) were calculated before and 10-15 min after the induction of TEA (bupivacaine 5 mg.ml-1). In Group B (n = 6) left ventricular end-diastolic pressure (LVEDP) and maximal dP/dt were recorded as in Group A. In Group C (n = 10) central haemodynamics were measured 10 min after i.v. metoprolol (0.5 mg.kg-1) and again 10-15 min after the addition of TEA. In Group D (n = 6) LVEDP and max dP/dt were measured as in Group C. The reduction in CO, SV, HR and max dP/dt was of the same magnitude with TEA and metoprolol. TEA lowered MAP by 17%, while metoprolol did not change MAP. Metoprolol caused an increase in LVEDP from 20.8 +/- 1.8 to 27.5 +/- 2.7 mmHg (2.8 +/- 0.2 to 3.7 +/- 0.4 kPa) (P less than 0.01), while TEA induced a decrease in LVEDP from 24.2 +/- 1.4 to 17.8 +/- 1.6 mmHg (3.2 +/- 0.2 to 2.4 +/- 0.2 kPa) (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Anaesthesia and Intensive Care, Sahlgrens Hospital, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Blomberg
authors.forename: S E
authors.initials: SE
authors.lastname: Ricksten
mesh_terms: D000767:Anesthesia, Epidural; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002045:Bupivacaine / Q000494:pharmacology*; D002302:Cardiac Output / Q000187:drug effects; D003243:Consciousness; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D009203:Myocardial Infarction / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013318:Stroke Volume / Q000187:drug effects; D013904:Thoracic Vertebrae; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D008790:Metoprolol; D002045:Bupivacaine