Propofol in ICU Settings: Understanding and Managing Anti-Arrhythmic, Pro-Arrhythmic Effects, and Propofol Infusion Syndrome

Propofol has revolutionized anesthesia and intensive care medicine owing to its favorable pharmacokinetic characteristics, fast onset, and short duration of action. This drug has been shown to be remarkably effective in numerous clinical scenarios. In addition, propofol has maintained an overwhelmingly favorable safety profile; however, it has been associated with both antiarrhythmic and proarrhythmic effects. This review concisely summarizes the dual arrhythmic cardiovascular effects of propofol and a rare but serious complication, propofol infusion syndrome (PRIS). We also discuss the need for careful patient evaluation, compliance with recommended infusion rates, and vigilant monitoring.

Propofol dose and efficacy of defibrillation testing during implantation of subcutaneous implantable cardioverter-defibrillators: A retrospective, single center cohort study

INTRODUCTION

Defibrillation testing (DFT) is recommended during subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Previous studies analyzing the potential interference of propofol with defibrillation threshold are inconsistent. The purpose of this study was to analyze whether propofol affects DFT post S-ICD placement.

METHODS

All patients with S-ICD implantation between 01/2017 and 11/2020 at the University Heart Center Freiburg were retrospectively analyzed. Two groups were generated depending on the success of the first shock during DFT. Implantation characteristics and dose of anesthetics were analyzed.

RESULTS

In 12 of the included 80 (15%) patients, first shock during DFT failed. The absolute dose of propofol was significantly higher in patients with first shock failure (median 653 mg [IQR 503-855]) compared to patients with first shock termination (376 mg [200-600]; p = 0.027). Doses of opioids and midazolam as well as type of anesthesia did not differ between the groups. A multivariable binary logistic regression analysis confirmed an independent association of first shock termination and propofol dose (per 100 mg: OR 0.73 (95% CI: 0.56-0.95); p = 0.021).

CONCLUSION

There is an independent association of propofol dose and first shock failure in routine S-ICD defibrillation testing.

Ventricular tachycardia converts to sinus rhythm after administration of propofol

Ventricular tachycardia (VT) is a major contributor to sudden cardiac death, and pharmacologic treatment options beyond antiarrhythmics are limited. Emerging data suggest sympathetic blocking agents such as propofol are a potential management option for VT refractory to first line antiarrhythmics. Previous literature has described fixed-dose propofol boluses and continuous infusions to convert ventricular arrhythmias; however, to our knowledge, there are no reports of a weight-based dosing strategy for VT. We present the case of a patient with amiodarone-refractory VT who received a 1 mg/kg propofol bolus in preparation for cardioversion and subsequently converted to normal sinus rhythm. The patient stabilized following these interventions, transferred to a tertiary care facility, and was discharged home with an implantable cardioverter defibrillator.

Etomidate Shows Prospect as an Anti-Arrhythmic Drug Conferring Safe Sedation and Sinus Conversion Simultaneously

This case is of a 76-year-old man with a known history of hypertension, type 2 diabetes mellitus, and ischemic heart disease, who presented to our department with chest pain and palpitations. His electrocardiogram showed a ventricular tachycardia (VT), but fortunately our patient was hemodynamically stable. A trial of adenosine was given to convert the patient’s heart back to sinus rhythm, but was unsuccessful and the rhythm remained as VT. Soon after, the patient suddenly became hemodynamically unstable as his blood pressure acutely declined; thus, the decision to perform a direct current cardioversion was taken. Bearing in mind that the patient was still awake, he was given 10 mg of intravenous etomidate as a pre-procedural sedative. During the time it took to prepare for the procedure, the patient’s rhythm reverted from VT to a regular sinus rhythm, raising his blood pressure back to normal and achieving hemodynamic stablility, negating the need of any electrical or chemical cardioversion. Our patient was then handed over to the cardiology team for an emergency percutaneous coronary intervention procedure and an implantable cardioverter-defibrillator procedure, both of which were successful. Etomidate was used in this case for the purpose of sedation, and as luck would have it, it seems that it had also incidentally reverted the arrhythmia back to normal.

Deep sedation as temporary bridge to definitive treatment of ventricular arrhythmia storm

Background:

Electrical storm and incessant ventricular tachycardia (VT) are characterized by the clustering of episodes of VT or ventricular fibrillation (VF) and are associated with a poor prognosis. Autonomic nervous system activity influences VT threshold, and deep sedation may be useful for the treatment of VT emergencies.

Methods:

We reviewed data from conscious patients admitted to our intensive care unit (ICU) due to monomorphic VT, polymorphic VT or VF at our tertiary center between 2010 and 2018.

Results:

A total of 46 conscious patients with recurrent ventricular arrhythmia, refractory to initial treatment, were referred to the ICU. The majority (n = 31) were stabilized on usual care. The remaining treatment-refractory 15 patients (57 years (range 9–74), 80% males, seven with implantable cardioverter-defibrillators) with VT/VF storm (n = 11) or incessant VT (n = 4) due to ischemic heart disease (n = 10), cardiomyopathy (n = 2), primary arrhythmia (n = 2) and one patient post valve surgery, were deeply sedated and intubated. A complete resolution of VT/VF within minutes to hours was achieved in 12 patients (80%), partial resolution in two (13%) and one (7%) patient died due to ventricular free-wall rupture. One patient with recurrent VT episodes needing repeated deep sedation developed necrotic caecum. No other major complications were seen. Thirteen (87%) patients were alive after a mean follow-up of 3.7 years.

Conclusion:

Deep sedation was effective and safe for the temporary management of malignant VT/VF refractory to usual treatment. In emergencies, deep sedation may be widely accessible at both secondary and tertiary centers and a clinically useful bridge to definitive treatment of VT.

Anaesthesia use in catheter ablation for atrial fibrillation: a systematic review and meta-analysis of observational studies

Objectives

This meta-analysis and systematic review seeks to compare both characteristic parameters and procedural outcomes of atrial fibrillation (AF) catheter ablation in patients under general anaesthesia (GA)/deep sedation and mild/moderate sedation.

Background

Catheter ablation has become a widely applied intervention for treating symptomatic AF and arrhythmias that are refractory to medical therapy. It can be conducted through from mild sedation to GA.

Methods

PubMed and Embase were searched up to July 2018 for randomised controlled trials, cohort and observational studies that assessed the outcomes of catheter ablation under GA/deep sedation or mild/moderate sedation. Nine studies were included in this meta-analysis after screening with the inclusion and exclusion criteria. Heterogeneity between studies and publication bias was evaluated by I² index and Egger's regression, respectively.

Results

Our meta-analysis found catheter AF ablation with GA/deep sedation to be associated with reduced risk of recurrence (RR: 0.79, 95% CI 0.56 to 1.13, p=0.20) and complications (RR: 0.95, 95% CI 0.64 to 1.42, p=0.82), though statistically insignificant. In terms of procedural parameters, there was no significant difference between the two groups for both procedural time (SMD: -0.13, 95% CI -0.90 to 0.63, p=0.74) and fluoroscopy time (SMD: -0.41, 95% CI -1.40 to 0.58, p=0.41). Univariate meta-regression did not reveal any covariates as a moderating factor for complication and recurrence risk.

Conclusion

Apart from an increased likelihood of procedural success, ablation by GA/deep sedation was found to be non-significantly different from the mild/moderate sedation approach in both procedural parameters and outcome measures.

Editor’s Choice- Sedation in the coronary intensive care unit: An adapted algorithm for critically ill cardiovascular patient

In the current era, cardiovascular intensive care units care for more complex patients who are far sicker than historical post-myocardial infarction patients, and sedation has become a common intervention in these units. Current sedation best practices derive mainly from non-cardiac units which limits their generalization to the critically ill cardiac patient. Thus, a great variability in sedation protocols, especially the selection of sedative agents, is commonly seen in daily practice across cardiac units. We present an updated review on sedation in cardiovascular critical care medicine with emphasis on the hemodynamic impact. The goal of this review is to generate a general sedation algorithm specific for the cardiac patient.

Sedation in cardiac arrhythmias management

INTRODUCTION

Procedural sedation is of paramount importance for a plethora of electrophysiological procedures. From electrical cardioversion to electrophysiology studies, device implantations, and catheter ablations, intraprocedural sedation and anesthesia have a pivotal role in allowing procedural success while ensuring patient safety and avoiding discomfort. Areas covered: The present review will discuss the current state-of-the-art in sedation and anesthesia during electrical cardioversion, cardiac implantable electronic device implantation, catheter ablation and electrophysiology studies. Specific information will be provided for each procedure in order to reach the core of this important clinical issue, and specific protocols will be compared. The main pro-arrhythmic and anti-arrhythmic effects of the most commonly used sedatives will also be discussed. Expert commentary: According to much recent evidence, the cardiologist can be the only person responsible for sedation administration in many settings, highlighting few safety issues associated with the absence of a dedicated anesthesiologist thus a concomitant reduction in costs. However, many concerns have been raised in allowing non-anesthesiologists to manage sedatives, as adverse events, while rare, could have catastrophic consequences. The present paper will highlight when a cardiologist-directed sedation is considered safe, how it should be performed, and the pros and cons related to this strategy.

Anesthesia in the Electrophysiology Laboratory

The electrophysiology suite is a foreign location to many anesthesiologists. The initial experience was with shorter procedures under conscious sedation, and the value of greater tailoring of the sedation/anesthesia by anesthesiologists was not perceived until practice patterns had already been established. Although better control of ventilation with general anesthesia may be expected, suppression of arrhythmias, blunting of the hemodynamic adaptation to induced arrhythmias, and interference by muscle relaxants with identification of the phrenic nerve may be seen. We review a range of electrophysiology procedures and discuss anesthetic approaches that balance patient safety and favorable outcomes.

Impact of deep sedation on the electrophysiological behavior of pulmonary vein and non-PV firing during catheter ablation for atrial fibrillation

PURPOSE

Catheter ablation for atrial fibrillation is performed with and without deep sedation, which could affect the arrhythmogenic activity during the procedure. We investigated the impact of sedation on electrophysiological properties in patients with AF who underwent catheter ablation.

METHODS

This study consisted of 255 consecutive patients with atrial fibrillation (229 males, persistent: 105 patients) who underwent a single-catheter ablation procedure. The patients were divided into the following two groups according to the depth of sedation during the procedure: group M (mild sedation with flunitrazepam in 138 patients) and group D (deep sedation with propofol in 117 patients). Peripheral oxygen saturation was continuously monitored via pulse oximetry throughout the procedure.

RESULTS

A spontaneous dissociated pulmonary vein activity after pulmonary vein isolation occurred more frequently in group M than in group D (29.1 vs 15.7%, P < 0.01). Adenosine-induced dormant pulmonary vein conduction was more frequently observed in group M than in group D (19.2 vs 13.0% P = 0.01). There were no significant differences in the incidence of non-pulmonary vein triggers between groups M and D (15.2 vs 11.1%, P = 0.53). The atrial fibrillation recurrence rate following the single procedure did not differ between the two groups (29.0 vs 26.5%, in groups M and D, P = 0.85).

CONCLUSIONS

Although deep sedation reduced the incidence of a dissociated pulmonary vein activity and dormant pulmonary vein conduction following pulmonary vein isolation, it did not affect the recurrence rate for atrial fibrillation after the procedure.

Inhibition of the cardiac Na⁺ channel α-subunit Nav1.5 by propofol and dexmedetomidine

Propofol and dexmedetomidine are very commonly used sedative agents. However, several case reports demonstrated cardiovascular adverse effects of these two sedatives. Both substances were previously demonstrated to quite potently inhibit neuronal voltage-gated Na(+) channels. Thus, a possible molecular mechanism for some of their cardiac side effects is an inhibition of cardiac voltage gated Na(+) channels. In this study, we therefore explored the effects of propofol and dexmedetomidine on the cardiac predominant Na(+) channel α-subunit Nav1.5. Effects of propofol and dexmedetomidine were investigated on constructs of the human α-subunit Nav1.5 stably expressed in HEK-293 cells by means of whole-cell patch clamp recordings. Both agents induced a concentration-dependent tonic inhibition of Nav1.5. The calculated IC50 value for propofol was 228 ± 10 μM, and for dexmedetomidine 170 ± 20 μM. Tonic block only marginally increased on inactivated channels, and a weak use-dependent block at 10 Hz was observed for dexmedetomidine (16 ± 2 % by 100 μM). The voltage dependencies of fast and slow inactivation as well as the time course of recovery from inactivation were shifted by both propofol and dexmedetomidine. Propofol (IC50 126 ± 47 μM) and dexmedetomidine (IC50 182 ± 27 μM) blocked the persistent sodium current induced by veratradine. Finally, the local-anesthetic (LA)-insensitive mutant Nav1.5-F1760A exhibited reduced tonic and use-dependent block by both substances. Dexmedetomidine was generally more potent as compared to propofol. Propofol and dexmedetomidine seem to interact with the LA-binding site to inhibit the cardiac Na(+) channel Nav1.5 in a state-dependent manner. These data suggest that Nav1.5 is a hitherto unrecognized molecular component of some cardiovascular side effects of these sedative agents.

Intravenous Anesthetic Propofol Inhibits Multiple Human Cardiac Potassium Channels

Background:

Propofol is widely used clinically for the induction and maintenance of anesthesia. Clinical case reports have shown that propofol has an antiatrial tachycardia/fibrillation effect; however, the related ionic mechanisms are not fully understood. The current study investigates the effects of propofol on human cardiac potassium channels.

Methods:

The whole cell patch voltage clamp technique was used to record transient outward potassium current (Ito) and ultrarapidly activating delayed rectifier potassium current (IKur) in human atrial myocytes and hKv1.5, human ether-à-go-go-related gene (hERG), and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells. Current clamp mode was used to record action potentials in human atrial myocytes.

Results:

In human atrial myocytes, propofol inhibited Ito in a concentration-dependent manner (IC50 = 33.5 ± 2.0 μM for peak current, n = 6) by blocking open channels without affecting the voltage-dependent kinetics or the recovery time constant; propofol decreased IKur (IC50 = 35.3 ± 1.9 μM, n = 6) in human atrial myocytes and inhibited hKv1.5 current expressed in HEK 293 cells by preferentially binding to the open channels. Action potential duration at 90% repolarization was slightly prolonged by 30 μM propofol in human atrial myocytes. In addition, propofol also suppressed hERG and hKCNQ1/hKCNE1 channels expressed in HEK 293 cells.

Conclusion:

Propofol inhibits multiple human cardiac potassium channels, including human atrial Ito and IKur, as well as hKv1.5, hERG, and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells, and slightly prolongs human atrial action potential duration, which may contribute to the antiatrial tachycardia/fibrillation effects observed in patients who receive propofol.

Cryptotanshinone and dihydrotanshinone I exhibit strong inhibition towards human liver microsome (HLM)-catalyzed propofol glucuronidation

Danshen is one of the most famous herbs in the world, and more and more danshen-prescribed drugs interactions have been reported in recent years. Evaluation of inhibition potential of danshen's major ingredients towards UDP-glucuronosyltransferases (UGTs) will be helpful for understanding detailed mechanisms for danshen-drugs interaction. Therefore, the aim of the present study is to investigate the inhibitory situation of cryptotanshinone and dihydrotanshinone I towards UGT enzyme-catalyzed propofol glucuronidation. In vitro the human liver microsome (HLM) incubation system was used, and the results showed that cryptotanshinone and dihydrotanshinone I exhibited dose-dependent inhibition towards HLM-catalyzed propofol glucuronidation. Dixon plot and Lineweaver-Burk plot showed that the inhibition type was best fit to competitive inhibition type for both cryptotanshinone and dihydrotanshinone I. The second plot using the slopes from the Lineweaver-Burk plot versus the concentrations of cryptotanshinone or dihydrotanshinone I was employed to calculate the inhibition parameters (Ki) to be 0.4 and 1.7μM, respectively. Using the reported maximum plasma concentration (Cmax), the altered in vivo exposure of propofol increased by 10% and 8.2% for the co-administration of dihydrotanshinone I and cryptotanshinone, respectively. All these results indicated the possible danshen-propofol interaction due to the inhibition of dihydrotanshinone I and cryptotanshinone towards the glucuronidation reaction of propofol.

Effects of propofol on ischemia-induced ventricular arrhythmias and mitochondrial ATP-sensitive potassium channels

AIM

To investigate the potential of propofol in suppressing ventricular arrhythmias and to examine whether mitochondrial ATP-sensitive potassium channels are involved.

METHODS

Male Sprague-Dawley rats were pretreated with intravenous infusion of propofol (Prop), a selective mitochondrial KATP channel inhibitor 5-hydroxydecanoate (5-HD), propofol plus 5-HD (Prop+5-HD), a potent mitochondrial K(ATP) channel opener diazoxide (DZ) or NS, respectively. The dosage of each drug was 10 mg/kg. The animals then underwent a 30 min-ligation of the left anterior descending artery. The severity of arrhythmias, the incidence of ventricular fibrillation (VF), and the time of the first run of ventricular arrhythmias were documented using an arrhythmia scoring system. Mitochondrial membrane potential (ΔΨm) was measured in freshly isolated rat cardiomyocytes with a fluorescence microscope.

RESULTS

The arrhythmia scores in the Prop and DZ group were 2.6(0-5) and 2.4(0-5), respectively, which were significantly lower than that in the control group [4.9(2-8)]. VF was not observed in both Prop and DZ groups. The first run of ventricular arrhythmias was significantly postponed in the Prop group (10.5±2.2 vs 7.3±1.9 min). Bracketing of propofol with 5-HD eliminated the anti-arrhythmic effect of propofol. In isolated rat cardiomyocytes, propofol (50 μmol/L) significantly decreased ΔΨm, but when propofol was co-administered with 5-HD, the effect on ΔΨm was reversed.

CONCLUSION

Propofol preconditioning suppresses ischemia-induced ventricular arrhythmias in the rat heart, which are proposed to be caused by opening of mitochondrial K(ATP) channels.

Propofol and arrhythmias: two sides of the coin

The hypnotic agent propofol is effective for the induction and maintenance of anesthesia. However, recent studies have shown that propofol administration is related to arrhythmias. Propofol displays both pro- and anti-arrhythmic effects in a concentration-dependent manner. Data indicate that propofol can convert supraventricular tachycardia and ventricular tachycardia and may inhibit the conduction system of the heart. The mechanism of the cardiac effects remains poorly defined and may involve ion channels, the autonomic nervous system and cardiac gap junctions. Specifically, sodium, calcium and potassium currents in cardiac cells are suppressed by clinically relevant concentrations of propofol. Propofol shortens the action potential duration (APD) but lessens the ischemia-induced decrease in the APD. Furthermore, propofol suppresses both sympathetic and parasympathetic tone and preserves gap junctions during ischemia. All of these effects cumulatively contribute to the antiarrhythmic and proarrhythmic properties of propofol.

Anesthesia induction with sevoflurane and propofol: evaluation of P-wave dispersion, QT and corrected QT intervals

The present study compared the effects of anesthesia induction with sevoflurane and propofol on hemodynamics, P-wave dispersion (Pwd), QT interval and corrected QT (QTc) interval. A total of 72 adult patients were included in this prospective study. All patients had control electrocardiograms (ECGs) before anesthesia induction. Anesthesia was induced with sevoflurane inhalation or intravenous propofol. Electrocardiography for all patients was performed during the 1(st) and 3(rd) minutes of induction, 3 minutes after administration of muscle relaxant, and at 5 minutes and 10 minutes after intubation. Pwd and QT intervals were measured on all ECGs. QTc intervals were determined using the Bazett formula. There was no significant difference in Pwd and QT and QTc intervals on control ECGs. In the sevoflurane group, except for control ECGs, Pwd and QTc interval on all ECGs were significantly longer than those in the propofol group (p < 0.05). We conclude that propofol should be used for anesthesia induction in patients with a predisposition to preoperative arrhythmias, and in those whose Pwd and QTc durations are prolonged on preoperative ECGs.

Randomized Study of Propofol Effect On Electrophysiological Properties of the Atrioventricular Node in Patients with Nodal Reentrant Tachycardia

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. Percutaneous catheter ablation is a technique to interrupt cardiac conduction pathways selectively. The anesthetist is challenged to provide a safe anesthetic which takes into account the electrophysiologist's requirements for minimal cardiac conduction interference. Propofol is an ideal drug. However, previous studies have shown that the infusion of propofol has sometimes been associated with bradyarrhythmias or conversion of arrhythmias to sinusal rhythm. The purpose of this report is to verify the interferences of propofol in the electrophysiological properties of the atrioventricular (AV) node conduction system in patients with AVNRT.

METHODS

Patients were randomly assigned to receive either a placebo or propofol at sedative doses. An electrophysiological study was performed consisting of measuring the anterograde (AERPFP) and retrograde effective refractory period of the fast (RERPFP) and the anterograde effective refractory period of the slow (AERPSP) AV nodal pathway. Reciprocating tachycardia was induced and the cycle length (CL) and atrial-His (AH), His-ventricular (HV), and ventriculoatrial (VA) intervals were measured.

RESULTS

Propofol did not cause alteration (P > 0.05) in the AERPFP or RERPFP and the AERPSP AV nodal pathway. The AH, HV, and VA intervals were not affected. Sustained reciprocating tachycardia could be induced in the all patients. All slow pathways were successfully identified and ablated.

CONCLUSION

Propofol has no effect on the electrophysiological properties of the AV node conduction system. It is thus a suitable anesthetic agent for use in patients undergoing ablative procedures.

Cardiovascular complications after GI endoscopy: occurrence and risks in a large hospital system

BACKGROUND

There is limited information concerning the risks for, and occurrence of, cardiovascular complications because of GI endoscopy. Published data are based on questionnaire surveys, which have a potential for bias. Moreover, available studies pertain exclusively to out-patients.

METHODS

In-patients and day-stay patients who incurred charges for endoscopy with endoscopic procedure coding from 1999 through 2001 were identified from a financial database for all 9 hospitals in a large health care system. From these patients, those considered "at risk" for cardiovascular complications were selected based on charges for cardioactive medications, cardiac enzyme determinations, or intensive care services on the day of or the day after endoscopy. Medical records were reviewed for 25% of these patients, selected at random, noting demographics, history, and a modified Goldman score in patients with cardiovascular complications (defined as arrhythmia, chest pain or anginal equivalent, hypotension or myocardial infarction occurring within 24 hours after endoscopy). Identical information was obtained from a random sample of 0.5% of the chart records for all patients undergoing endoscopy.

RESULTS

Patients who underwent endoscopy were not reliably identified for one hospital. This hospital was omitted from the calculation of the extrapolated rate of complication occurrence, but patients identified through chart review as having or not having a complication after endoscopy were included in the risk analysis. The extrapolated rate of occurrence of cardiovascular complications was 308: 95% CI [197, 457] per 100,000 procedures. Independent risk factors were: male gender, modified Goldman score, and use of propofol.

CONCLUSIONS

In this study of patients undergoing hospital-based GI endoscopy, the risk of procedure-related cardiovascular complications was 2 to 70 times higher than previously reported. This finding may be ascribed to differences in the populations sampled and to a case-finding method that minimized reporting and ascertainment biases.

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.