Short-Term Effects of Ketamine and Isoflurane on Left Ventricular Ejection Fraction in an Experimental Swine Model

Abstract

Background. General anesthesia is an essential element of experimental medical procedures. Ketamine and isoflurane are agents commonly used to induce and maintain anesthesia in animals. The cardiovascular effects of these anesthetic agents are diverse, and the response of global myocardial function is unknown. Methods. In a series of 15 swine, echocardiography measurements of left ventricular ejection fraction (LVEF) were obtained before the animals received anesthesia (baseline), after an intramuscular injection of ketamine (postketamine) and after inhaled isoflurane (postisoflurane). Results. The mean LVEF of an unanesthetized swine was 47 ± 3%. There was a significant decrease in the mean LVEF after administration of ketamine to 41 + 6.5% (P = 0.003). The addition of inhaled isoflurane did not result in further decrease in mean LVEF (mean LVEF 38 ± 7.2%, P = 0.22). Eight of the swine had an increase in their LVEF with sympathetic stimulation. Conclusions. In our experimental model the administration of ketamine was associated with decreased LV function. The decrease may be largely secondary to a blunting of sympathetic tone. The addition of isoflurane to ketamine did not significantly change LV function. A significant number of animals had returned to preanesthesia LV function with sympathetic stimulation.

Overexpression myocardial inducible nitric oxide synthase exacerbates cardiac dysfunction and beta-adrenergic desensitization in experimental hypothyroidism

“…The time constant of LV relaxation (τ) was significantly increased (hypothyroid:21.8 vs control: 10.9 ms) accompanied by 38% reduced LV peak filling rate of dV/dt max (3443 vs 5531 μl/sec) and 28% decrease in stroke volume (SV). In the current study, anesthesia agent of ketamine was used to induce and maintain anesthesia; consistent with past reports 10, 26 , we obtained relatively lower ejection fraction (EF) values in both groups 10, 26 . However, compared with controls, in the hypothyroid rats, EF still significantly reduced 26% (hypothyroid: 40% vs control: 54%) due to the significantly decreased SV, and cardiac output decreased by 54%.…”

“…Second, general anesthesia is an essential element of experimental medical procedures. Administration of ketamine was reported to be associated with significantly decreased LV EF 10, 26 . In the current study, ketamine was used to induce and maintain anesthesia.…”

“…In addition, isoproterenol failed to cause significant increase in the dP/dt max . This may be due to several factors: 1) ketamine use could blunting sympathetic tone 10, 26 which may attenuate normal isoproterenol-produced increases in EF and dP/dt max . 2) We used a very small amount of isoproterenol, only 0.5 ml of 10 −8 M. We are trying to mimic the physiologic stress to determine the β-AR reserve; 3) The maximum rate of LV pressure, dP/dt max is a convenient index for LV contractile state, it is determined by myocardial contractility, heart rate, and the loading conditions on the ventricle.…”

Ketamine may be related to minor troponin elevations in children undergoing minor procedures in the ED

“…However, in vitro studies report concerns on ketamine that may be related to decreased cardiac contractility or myocardial injury related to higher doses or longer period of administration (3,4). In the present study, we aimed to determine whether ketamine is related A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 4 to myocardial injury in children undergoing minor procedures by measuring high sensitive troponin.…”

“…In the present study, we aimed to determine whether ketamine is related A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 4 to myocardial injury in children undergoing minor procedures by measuring high sensitive troponin.…”