Effects of isoflurane versus halothane on myocardial contractility in rabbits: assessment with transthoracic two-dimensional echocardiography.
The effects of isoflurane versus halothane on cardiac contractility were evaluated by two-dimensional (2D) transthoracic echocardiography in rabbits. The relationship between the left ventricular end-systolic wall stress (LVESWS) and the velocity of heart rate corrected circumferential fibre shortening (Vcfc) was used. Arterial blood pressure, heart rate, left ventricular pressure and transthoracic 2D echocardiogrphic data were determined at 1 MAC (minimum alveolar concentration) of halothane or isoflurane, both with 50% nitrous oxide. Drug-induced changes in pre- and afterload were performed in all study animals to assess the left ventricular contractile response over a wide range. LVESWS and Vcfc were calculated on videotape recorded M-mode tracings. Mean heart rate and arterial blood pressure were not significantly different between the two groups. Myocardial contractility under isoflurane/nitrous oxide anaesthesia was significantly higher than under halothane/nitrous oxide anaesthesia at 1 MAC. The results of the present study confirm data obtained from humans and other animal species and suggest that, in rabbits, myocardial contractility is best preserved by inhalation of isoflurane. Isoflurane should therefore be preferred over halothane, especially in cases of prolonged anaesthetic procedures.
Marano
G
G
Laboratorio di Farmacologia, Istituto Superiore di Sanità, Rome, Italy. pimarano@iss.it
Formigari
R
R
Grigioni
M
M
Vergari
A
A
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D018619:Echocardiography, Doppler, Pulsed / Q000379:methods / Q000662:veterinary*; D017548:Echocardiography, Transesophageal / Q000379:methods / Q000662:veterinary*; D006221:Halothane / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D017725:Ventricular Pressure / Q000187:drug effects
D018685:Anesthetics, Inhalation; D007530:Isoflurane; D006221:Halothane