Influence of isoflurane on left atrial function in dogs with pacing-induced cardiomyopathy: evaluation with pressure-volume relationships.
OBJECTIVE
The actions of volatile anesthetics on left ventricular (LV) function in normal and failing hearts have been previously evaluated, but the effects of these agents on left atrial (LA) function in the presence of LV dysfunction are unknown. The hypothesis was tested that isoflurane alters LA mechanics evaluated with pressure-volume relations.


METHODS
Prospective.


METHODS
Laboratory.


METHODS
Barbiturate-anesthetized dogs (n = 8) were instrumented for measurement of aortic, LA, and LV pressures (micromanometers), and LA volume (epicardial orthogonal sonomicrometers) after 3 weeks of rapid ventricular pacing (220 beats/min).


METHODS
LA myocardial contractility (E(es)) was assessed with end-systolic pressure-volume relations. LA stroke work and reservoir function were assessed by A and V loop area, respectively, from the steady-state pressure-volume diagram. LA-LV coupling was determined by the ratio of E(es) to LV elastance (E(LV)). Dogs received 0.6, 0.9, and 1.2 minimum alveolar concentration isoflurane in a random manner, and LA function was determined after a 20-minute equilibration at each dose.


RESULTS
Isoflurane significantly (p < 0.05) decreased heart rate, mean arterial pressure, LV end-systolic pressure, and LV +dP/dt(max). Isoflurane produced dose-related reductions in E(es) and E(es)/E(LV). Declines in LA stroke work, emptying fraction, reservoir volume, V loop area, and the active LA contribution to LV filling also occurred.


CONCLUSIONS
The results indicate that isoflurane depresses LA myocardial contractility, impairs LA-LV coupling, and reduces active LA contribution to LV filling in dogs with pacing-induced cardiomyopathy. The impact of isoflurane on LA function in the presence of LV dysfunction has profound effects on cardiac performance.
Kehl
Franz
F
Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Ladisa
John F
JF
Hettrick
Douglas A
DA
Kersten
Judy R
JR
Warltier
David C
DC
Pagel
Paul S
PS
D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D016279:Atrial Function, Left / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D002306:Cardiac Volume / Q000187:drug effects*; D009202:Cardiomyopathies / Q000209:etiology / Q000503:physiopathology*; D004195:Disease Models, Animal; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D007530:Isoflurane / Q000494:pharmacology*; D011446:Prospective Studies; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D017725:Ventricular Pressure / Q000187:drug effects
D018685:Anesthetics, Inhalation; D007530:Isoflurane