Comparative effects of thiopental and propofol on atrial vulnerability: electrophysiological study in a porcine model including acute alcoholic intoxication.
BACKGROUND
Atrial tachyarrhythmias (AT) frequently complicate the perioperative period. Alcohol intoxication is a recognized causative factor for dysrrhythmias. We studied the effects of propofol and thiopental on atrial electrophysiology and vulnerability to AT in a closed-chest porcine model in which AT are facilitated by ethanol.


METHODS
Thirty-eight pigs were randomly assigned to thiopental (T-group, n=19) or propofol (P-group n=19). All animals were assigned to undergo a right atrial electrical stimulation protocol (RASP) at baseline. Thirty pigs were assigned to undergo additional RASP during ethanol infusion, while the remaining eight were assigned to undergo additional RASP during saline infusion (control group). We analysed effective refractory period (ERP), and intra-atrial conduction interval (ICI) (between atrial sites 4 cm apart), at several cycle lengths (CL).


RESULTS
There were no significant differences at baseline. During ethanol infusion, propofol produced a greater rate-dependent decrease in excitability, manifested by a longer minimum paced CL with 1:1 atrial capture: 145 (11) vs 164 (27) ms in the T- and P-group, respectively (P=0.01). Propofol was associated with a greater rate-related slowing in conduction: difference between ICI at CL of 300 ms and ICI at minimum CL: 30 ms in P-group and 22 ms in T-group (P<0.03). In the P-group we observed a longer duration of induced arrhythmias (145 (131) vs 74 (91) s, P<0.03) and a higher proportion with atrial flutter (AFl) (76 vs 19%, P<0.001).


CONCLUSIONS
Propofol in this model was more arrhythmogenic than thiopental, as manifested by a longer duration of induced arrhythmias, particularly AFI.
Zaballos
M
M
Department of Anesthesiology, Hospital Universitario Gregorio Marañón, Madrid, Spain. alma@nacom.es
Almendral
J
J
Anadón
M J
MJ
González
P
P
Navia
J
J
D000435:Alcoholic Intoxication / Q000150:complications* / Q000503:physiopathology; D018686:Anesthetics, Intravenous / Q000633:toxicity*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000209:etiology; D001282:Atrial Flutter / Q000139:chemically induced; D016280:Atrial Function, Right / Q000187:drug effects; D004195:Disease Models, Animal; D004594:Electrophysiology; D000431:Ethanol; D015742:Propofol / Q000633:toxicity*; D011897:Random Allocation; D013552:Swine; D013874:Thiopental / Q000633:toxicity*
D018686:Anesthetics, Intravenous; D000431:Ethanol; D013874:Thiopental; D015742:Propofol