Usefulness of intravenous propofol anesthesia for radiofrequency catheter ablation in patients with tachyarrhythmias: infeasibility for pediatric patients with ectopic atrial tachycardia

Management of Anesthesia for Procedures in the Cardiac Electrophysiology Laboratory

The complexity of cardiac electrophysiology procedures has increased significantly over the past three decades. Anesthesia requirements of these procedures can be different based on patient- and procedure-specific factors. This manuscript outlines various anesthesia strategies for cardiac implantable electronic devices and electrophysiology procedures including pre-procedural, procedural and post-procedural management. A team-based approach with collaboration between cardiac electrophysiologists and anesthesiologists is required with careful pre-procedural and intra-procedural planning. Given the recent advances in electrophysiology, there is a need for specialized cardiac electrophysiology anesthesia care to improve the efficacy and safety of the procedures.

Anaesthetic management of paediatric patients undergoing electrophysiology study and ablation for supraventricular tachycardia: A focused narrative review

Every year, 80,000-100,000 ablation procedures take place in the United States and approximately 1% of these involve paediatric patients. As the paediatric population undergoing catheter ablation to treat dysrhythmia is constantly growing, involvement of anaesthesiologists in the cardiac electrophysiology laboratory is simultaneously increasing. Compared with the adult population, paediatric patients need deeper sedation or general anaesthesia (GA) to guarantee motionlessness and preserve comfort. As a result, the anaesthesiologist working in this setting should keep in mind heart physiopathology as well as possible interactions between anaesthetic drugs and arrhythmia. In fact, drug-induced suppression of accessory pathways (APs) conduction capacity is a major concern for completing a successful electrophysiology study (EPS). Nevertheless, the literature on this topic is scarce and the optimal type of anaesthesia in EPS and ablation procedures in children is still controversial. Thus, the main goal of the present review is to collect the literature published so far on the effects on cardiac conduction tissue of the drugs commonly employed for sedation/GA in the cath lab for EPS and ablation procedures to treat supraventricular tachycardia in patients aged <18 years.

Impact of dexmedetomidine on electrophysiological properties and arrhythmia inducibility in adult patients referred for reentrant supraventricular tachycardia ablation

BACKGROUND

Drugs used for sedation/analgesia may affect the basic cardiac electrophysiologic properties or even supraventricular tachycardia (SVT) inducibility. Dexmedetomidine (DEX) is a selective alpha-2 adrenergic agonist with sedative and analgesic properties. A comprehensive evaluation on use of DEX for reentrant SVT ablation in adults is lacking. The present study aims to systematically assess the impact of DEX on cardiac electrophysiology and SVT inducibility.

METHODS

Hemodynamic, electrocardiographic, and electrophysiological parameters and SVT inducibility were assessed before and after DEX infusion in patients scheduled for ablation of reentrant SVT.

RESULTS

The population of this prospective observational study included 55 patients (mean age of 58.7 ± 14 years, 29 males [52.7%]). A decrease in systolic and diastolic blood pressure and in heart rate was observed after DEX infusion (p = 0.001 for all). DEX increased corrected sinus node refractory time, atrial effective refractory period, AH interval, AV Wenckebach cycle length, and AV node effective refractory period without affecting the His-Purkinje conduction or ventricular myocardium refractoriness. No AV blocks or sinus arrests occurred during DEX infusion. Globally, there was no difference in SVT inducibility in basal condition or after DEX infusion (46/55 [83.6%] vs. 43/55 [78.1%] patients; p = 0.55), without a difference in isoprenaline use (p = 1.0). In 4 (7.3%) cases, the SVT was inducible only after DEX infusion. In 34.5% of cases, DEX infusion unmasked the presence of an obstructive sleeping respiratory pattern, represented mainly by snoring.

CONCLUSIONS

DEX depresses sinus node function and prolongs atrioventricular refractoriness without significantly affecting the rate of SVT inducibility in patients scheduled for reentrant SVT ablation.

Comparison of the effects of propofol and alfaxalone on the electrocardiogram of dogs, with particular reference to QT interval

Cardiac electrical activity is often altered by administration of anesthetic drugs. While the effects of propofol in this regard have previously been described in dogs, to date, there are no reports of the effect of alfaxalone. This study investigated the impact of both propofol and alfaxalone on the ECG of 60 dogs, after premedication with acepromazine and methadone. Heart rate increased significantly in both groups. The PR and QRS intervals were significantly increased following propofol while with alfaxalone the QRS duration was significantly increased and ST segment depression was observed. The QT and JT interval were significantly shorter following induction with alfaxalone, but, when corrected (c) for heart rate, QTc and JTc in both groups were significantly greater following induction. When comparing the magnitude of change between groups, the change in RR interval was greater in the alfaxalone group. The change in both QT and JT intervals were significantly greater following alfaxalone, but when QTc and JTc intervals were compared, there were no significant differences between the two drugs. The similarly increased QTc produced by both drugs may suggest comparable proarrhythmic effects.

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.

Anesthetic Considerations in the Electrophysiology Laboratory: A Comprehensive Review

Catheter ablation procedures for arrhythmias or implantation and/or extraction of cardiac pacemakers can present many clinical challenges. It is imperative that there is clear communication and understanding between the anesthesiologist and electrophysiologist during the perioperative period regarding the mode of ventilation, hemodynamic considerations, and various procedural complications. This article provides a comprehensive narrative review of the anesthetic techniques and considerations for catheter ablation procedures, ventilatory modes using techniques such as high-frequency jet ventilation, and strategies such as esophageal deviation and luminal temperature monitoring to decrease the risk of esophageal injury during catheter ablation. Various hemodynamic considerations, such as the intraprocedural triaging of cardiac tamponade and fluid administration during catheter ablation, also are discussed. Finally, this review briefly highlights the early research findings on pulse-field ablation, a new and evolving ablation modality.

Inducibility of atrioventricular nodal reentrant tachycardia and ectopic atrial tachycardia in children under general anesthesia

BACKGROUND

In children, invasive electrophysiological studies (EPS) and radiofrequency catheter ablations (RFA) of supraventricular tachycardia (SVT) are often performed under general anesthesia. Atrioventricular nodal reentrant tachycardia (AVNRT) and ectopic atrial tachycardia (EAT) must be inducible during EPS as reliable diagnosis and subsequent therapy are not possible in sinus rhythm. This study aims to assess the problem of noninducible AVNRT and EAT under general anesthesia.

METHODS AND RESULTS

Anesthesia protocols of 166 patients undergoing EPS were retrospectively analyzed. 122 AVNRT patients were compared to 22 whose tachycardia was not inducible but probably due to an AVNRT mechanism. Another 16 patients with inducible EAT were compared to 6 whose EAT appeared on surface ECG but not during EPS. Demographic characteristics were similar among all groups. Inducibility did not differ (p = 0.42) between AVNRT patients with inhalational anesthesia (sevoflurane and/or nitrous oxide) and patients with intravenous anesthesia (propofol with/without remifentanil). The EAT group exhibited lower inducibility under intravenous anesthesia (64%) than under inhalational (88%), however without significance (p = 0.35).

CONCLUSION

Tachycardia induction succeeds with similar frequency under both inhalational and intravenous general anesthesia in children with AVNRT. In children with EAT, inhalational anesthesia is associated with a trend towards better inducibility. This article is protected by copyright. All rights reserved.

Effect of Dexmedetomidine on Tachyarrhythmias After Cardiac Surgery: A Systematic Review and Meta-Analysis

ABSTRACT

Tachyarrhythmias after cardiac surgery is a common occurrence in clinical practice, which can be life threatening. We searched 6 databases, including Embase, PubMed, Cochrane, CNKI, Wanfang, and Sinomed, to evaluate the effect of dexmedetomidine on tachyarrhythmias after adult cardiac surgery. The primary end point was the number of patients with atrial fibrillation (AF) after cardiac surgery. The secondary end points included the number of patients with supraventricular tachycardia or with ventricular tachycardia or with ventricular fibrillation or with myocardial infarction or deceased patients, the duration of mechanical ventilation, the intensive care unit stay, hospital stay, and the number of patients with bradycardia and those with hypotension. Among the 1388 retrieved studies, 18 studies (n = 3171 participants) met our inclusion criteria. Dexmedetomidine reduced the incidence of AF by 17% [relative risk (RR) = 0.83; 95% confidence interval (CI), 0.73-0.93; P = 0.002]. Through subgroup analysis, we found that when the maintenance dose of dexmedetomidine was >0.7 µg·kg-1·h-1, the effect of preventing AF was obvious (RR = 0.58; 95%CI 0.43-0.78; P = 0.0003). Dexmedetomidine also reduced the incidence of supraventricular tachycardia by approximately 70% (RR = 0.29; 95% CI, 0.11-0.77; P = 0.01) and the incidence of ventricular tachycardia by approximately 80% (RR = 0.23; 95% CI, 0.08-0.63; P = 0.004) but had no effect on ventricular fibrillation (RR = 1.02; 95% CI, 0.14-7.31; P = 0.99). The major side effect of dexmedetomidine was bradycardia. Dexmedetomidine can reduce the incidence of AF (especially high dosages), supraventricular tachycardia, and ventricular tachycardia after cardiac surgery in adults, but it does not affect the occurrence of ventricular fibrillation.

Outcomes of deep sedation for catheter ablation of paroxysmal supraventricular tachycardia, with adaptive servo ventilation

BACKGROUND

Catheter ablation for paroxysmal supraventricular tachycardia (PSVT) is an established treatment, but the effect of deep sedation on PSVT inducibility remains unclear.

AIM

We sought to examine PSVT inducibility and outcomes of catheter ablation under deep sedation using adaptive servo ventilation (ASV).

METHODS

We retrospectively evaluated consecutive patients who underwent catheter ablation for PSVT under deep sedation (Propofol + Dexmedetomidine) with use of ASV. Anesthetic depth was controlled with BIS™ monitoring, and phenylephrine was administered to prevent anesthesia-induced hypotension. PSVT induction was attempted in all patients using extrastimuli at baseline, and after isoproterenol (ISP) infusion when necessary.

RESULTS

PSVT was successfully induced in 145 of 147 patients, although ISP infusion was required in the majority (89%). The PSVT was atrioventricular nodal reentrant tachycardia (AVNRT) in 77 (53%), atrioventricular reciprocating tachycardia (AVRT) in 51 (35%), and atrial tachycardia (AT) in 17 (12%). A higher ISP dose was required for AT compared to other PSVT (AVNRT: 0.06 (IQR 0.03-0.06) vs AVRT: 0.03 (0.02-0.06) vs AT: 0.06 (0.03-0.12) mg/h, P = .013). More than half (51%) of the patients developed hypotension requiring phenylephrine; these patients were older. Acute success was obtained in 99% (patients with AVNRT had endpoints with single echo on ISP in 46%). Long-term success rate was 136 of 144 (94%) (AVNRT 96%, AVRT 92%, and AT 93%). There were no complications related to deep sedation.

CONCLUSIONS

Deep sedation with use of ASV is a feasible anesthesia strategy for catheter ablation of PSVT with good long-term outcome. PSVT remains inducible if ISP is used.

Propofol suppresses the His-ventricular conduction in paediatric patients

What is known and objective

Propofol is the most commonly used intravenous anaesthetic worldwide and is considered to be safe for all ages. However, there have been some reports that propofol induces severe atrioventricular (AV) blocks in humans and some studies demonstrated that propofol suppressed the cardiac conduction system in animals. A precise mechanism by which the block is induced has not been elucidated yet in humans. The objective of this study was to investigate the effects of propofol on the cardiac conduction system and the cardiac autonomic nervous balance in children.

Methods

We enrolled 23 paediatric patients (age: 6‐15 years; males: 16, females: 7) who were scheduled to undergo radiofrequency catheter ablation (RFCA) under general anaesthesia. Anaesthesia was induced with 2 mg/kg propofol and 0.5 µg/kg/min remifentanil, and tracheal intubation was performed with the aid of 1 mg/kg rocuronium. Anaesthesia was maintained with 5‐7 mg/kg/h propofol and 0.2 µg/kg/min remifentanil during the RFCA. After the completion of the RFCA, anaesthesia was further maintained with 5 mg/kg/h propofol and 0.2 µg/kg/min remifentanil for at least 10 min (LC: low propofol concentration state), followed by the injection of 2 mg/kg propofol and the infusion of 10 mg/kg/h propofol for 10 min (HC: high propofol concentration state). The sinus node recovery time (SNRT), sinoatrial conduction time (SACT), atrial‐His (AH) interval and the His‐ventricular (HV) interval were measured at the end of both the LC and HC. Cardiac autonomic regulation was simultaneously assessed based on heart rate variability.

Results and discussion

Propofol significantly suppressed intrinsic cardiac HV conduction, but did not affect the SNRT, SACT or the AH interval. As HV blocks, which occur below the His bundle, are often life‐threatening, the HV conduction delay may be a cause of severe AV blocks induced by propofol. Propofol directly suppressed parasympathetic nerve activity, and sympathetic nerve activity was also suppressed.

What is new and conclusion

These results indicate that propofol suppresses the HV conduction and might help to elucidate the mechanism by which propofol causes lethal AV blocks.

Dexmedetomidine Sedation for Paroxysmal Supraventricular Tachycardia Ablation Is Not Associated With Alteration of Arrhythmia Inducibility

BACKGROUND

Dexmedetomidine (Dex) is an attractive agent for procedural sedation due to its unique pharmacodynamic profile, specifically affording predictable sedation without concurrent respiratory depression. However, Dex has previously been reported to prevent or terminate arrhythmias. The purpose of this study was to investigate paroxysmal supraventricular tachycardia (PSVT) inducibility and homeostatic stability during electrophysiology studies (EPSs) and ablation when a standardized Dex protocol was used as the primary sedation agent.

METHODS

We performed a retrospective review of 163 consecutive procedures for PSVT ablation that received Dex as the primary sedative with adjunct fentanyl and midazolam boluses (DEX-FENT-MIDAZ). This cohort was compared to 163 consecutive control procedures wherein strictly fentanyl and midazolam were used for sedation. The primary outcome reviewed was PSVT inducibility assessed before ablation. Reviewed secondary outcomes included level of sedation and intraprocedure hemodynamics and oxygenation.

RESULTS

The arrhythmia profiles of the DEX-FENT-MIDAZ and control cohorts were very similar. The overall incidence of a "negative" EPSs in which arrhythmia was not induced was 24% in the DEX-FENT-MIDAZ group and 26% in the control group (P = .7). Unintended deep sedation was significantly less with DEX-FENT-MIDAZ (4.3% vs 27%; P ≤ .0001). However, DEX-FENT-MIDAZ use was associated with a higher incidence of intraprocedure hypotension.

CONCLUSIONS

Dex sedation during EPSs is not associated with a reduction in PSVT inducibility. The therapeutic utility of Dex during EPS arises from the predictable sedation Dex affords but is associated with an increased incidence of intraprocedure hypotension.

Electrophysiological effects of desflurane in children with Wolff-Parkinson-White syndrome: a randomized crossover study

BACKGROUND

We hypothesized that, compared with propofol, desflurane prolongs the antegrade accessory pathway effective refractory period (APERP) in children undergoing radiofrequency catheter ablation for Wolff-Parkinson-White (WPW) syndrome.

METHODS

In this randomized crossover study, children aged 4.1-16.1 years undergoing radiofrequency catheter ablation for WPW syndrome were randomly divided into four groups according to the concentration of desflurane and anesthetics used in the first and the second electrophysiological studies (EPS). After induction of general anesthesia with propofol and tracheal intubation, they received one of the following regimens: 0.5 minimum alveolar concentration (MAC) desflurane (first EPS) and propofol (second EPS) (Des0.5-Prop group, n = 8); propofol (first EPS) and 0.5 MAC desflurane (second EPS) (Prop-Des0.5 group, n = 9); 1 MAC desflurane (first EPS) and propofol (second EPS) (Des1.0-Prop group, n = 10); propofol (first EPS) and 1 MAC desflurane (second EPS) (Prop-Des1.0 group, n = 9). Radiofrequency catheter ablation was performed upon completion of EPS. Sample size was determined to detect a difference in the APERP.

RESULTS

Desflurane at 1.0 MAC significantly prolonged the APERP compared with propofol, but did not affect the sinoatrial conduction time, atrio-His interval or atrioventricular node effective refractory period. Supraventricular tachycardia was induced in all children receiving propofol, but not induced in 1 and 4 children receiving 0.5 MAC and 1.0 MAC desflurane, respectively.

CONCLUSION

Desflurane enhances the refractoriness and may block the electrical conduction of the atrioventricular accessory pathway, and is therefore not suitable for use in children undergoing radiofrequency catheter ablation for WPW syndrome.

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.

Dexmedetomidine use in patients undergoing electrophysiological study for supraventricular tachyarrhythmias

BACKGROUND

Dexmedetomidine is a selective alpha-2 adrenergic agonist with sedative, analgesic, and anxiolytic properties. Dexmedetomidine has not been approved for use in pediatrics. Dexmedetomidine has been reported to depress sinus node and atrioventricular nodal function in pediatric patients; it has been suggested that the use of dexmedetomidine may not be desirable during electrophysiological studies.

AIM

We hypothesize that the use of dexmedetomidine does not inhibit the induction of supraventricular tachyarrhythmias (SVT) during electrophysiological studies and does not inhibit the ablation of such arrhythmias.

METHODS

In this retrospective, observational cohort study, we reviewed all cases presenting to the cardiac catheterization laboratory for diagnosis or treatment of SVT since 2007. All cases were performed by the same electrophysiologist. The anesthesia was provided by one of the three cardiac anesthesiologists. One cardiac anesthesiologist did not use dexmedetomidine during electrophysiological studies. A second used dexmedetomidine, but only with an infusion. The third used dexmedetomidine with a primary bolus and an infusion. Thus, the patients were stratified into three different groups: Group 1 patients did not receive any dexmedetomidine. Group 2 patients received a dexmedetomidine infusion of 0.5-1 μg·kg^-1 ·h^-1 . Group 3 patients received a dexmedetomidine infusion of 0.5-1 μg·kg^-1 ·h^-1 and a dexmedetomidine bolus prior to the infusion of 0.5-1 μg·kg^-1 . We then compared those patients for the following variables: demographic data including age, sex, height, weight; anesthetic data such as, mask vs intravenous induction, identity of induction agent, amount of sevoflurane and propofol used; amount of dexmedetomidine used; presence of congenital heart disease and other comorbidities; the need for isoproterenol and dose, the need for adenosine and dose, and the need for any other medications to affect rhythm both before and after radiofrequency ablation; the ability to induce the arrhythmia, the type of arrhythmia, the presence of Wolff-Parkinson-White syndrome, the presence of an accessory pathway, the ablation rate, and the recurrence rate.

RESULTS

There was no difference in the anesthetic agents, except there was a lesser amount of propofol used in the dexmedetomidine groups (χ²₍₂₎ = 48.2, P < 0.001). There was no difference in the electrophysiological parameters among groups, except the Group 1 patients did require the use of isoproterenol in the preablation period less often compared to the dexmedetomidine groups (χ²₍₂₎ = 15.2, P < 0.01). However, with the greater use of isoproterenol, there was no difference in the ability to induce the arrhythmia. Moreover, the percentage of patients ablated, and the recurrence rate among groups was the same.

CONCLUSIONS

We conclude that dexmedetomidine does not interfere with the conduct of electrophysiological studies for SVT and the successful ablation of such arrhythmias. However, dexmedetomidine use did result in a greater need for isoproterenol.

Ambulatory anesthesia for the cardiac catheterization and electrophysiology laboratories

The cardiac catheterization laboratory (CCL) and electrophysiology laboratory (EPL) environments present unique clinical challenges. These challenges include unfamiliar work areas and staff, limited space with physical barriers separating the patient from the care provider, remote locations, and procedures with rare but potentially catastrophic clinical complications. Ambulatory anesthesiologists must familiarize themselves with these new surroundings and practice vigilant preoperative planning and continual communication with the proceduralist and team. In the future, the need for anesthesiologists in the CCL and EPL will continue to grow as procedures increase in complexity and duration.

Deep sedation in patients undergoing atrioventricular nodal reentry tachycardia ablation

BACKGROUND

General anesthesia and deep sedation can be used during cardiac EPS to relief pain and provide comfort and immobility, but many electrophysiologists avoid sedation for better arrhythmia induction.

OBJECTIVE

To determine anesthesia effects in ablation procedures in adults, we used intravenous anesthetic agents in patients who underwent slow pathway ablation.

PATIENTS AND METHODS

One hundred patients who were to undergo radiofrequency catheter ablation were randomly assigned to with and without intravenous anesthesia groups. All patients had palpitation with a documented electrocardiography (ECG) compatible with atrio-ventricular nodal reentrant tachycardia (AVNRT). We used propofol, fentanyl and midazolam for intravenous sedation. Electrophysiological parameters were checked for the two groups and compared before and after the ablation.

RESULTS

Electrophysiological parameters were not significantly different in the two groups. In the anesthetic group, patients were more satisfied with the procedure (P value < 0. 001).

CONCLUSIONS

Intravenous anesthesia could be done safely in patients who underwent electrophysiological procedures. It had no effect on arrhythmia induction or slow pathway ablation in patients with documented AVNRT.

Current approaches to pediatric heart catheterizations

Sedation for pediatric cardiac catheterization is a common requirement in many institutions. As the field of cardiac catheterization has evolved, the provision of sedation for these procedures has been varied. Increasingly the demand is for dedicated personnel focused on monitoring and delivery of sedation while in the catheterization suite. This article describes the considerations one must use when undertaking these cases.

Effects of remifentanil anesthesia on cardiac electrophysiologic properties in children undergoing catheter ablation of supraventricular tachycardia

Remifentanil is commonly used during anesthesia in pediatric electrophysiologic studies (EPS). The purpose of this study is to determine the effects of remifentanil on the cardiac electrophysiologic properties of children undergoing ablation of supraventricular tachycardia (SVT). A prospective study was performed in patients undergoing EPS before ablation of SVT. Each patient received two different anesthetic protocols: protocol 1 = propofol (200 mcg/kg/min) and protocol 2 = propofol (120 mcg/kg/min) plus remifentanil (0.3 mcg/kg/min). EPS data were measured during the steady state of each protocol. Paired Student t test was performed for analysis of continuous data. All p values <0.05 were considered statistically significant. Fifteen patients were enrolled between April 2005 and January 2006. The mean age was 13.3 ± 2.9 years (range 6.7 to 17.7). Seven patients had atrioventricular (AV) nodal re-entry tachycardia; 5 patients had Wolff-Parkinson-White syndrome; 2 patients had a concealed accessory pathway; and 1 patient was not inducible. Of the 14 patients who underwent ablation, 13 (93%) achieved successful. The baseline sinus cycle length extended from 884 ± 141 ms during protocol 1 to 980 ± 165 ms during protocol 2 (p = 0.01), and the Wenckebach cycle length lengthened from 377 ± 96 ms to 406 ± 109 ms (p = 0.01). No other variables measured (atrial-His (AH) and His-ventricular (HV) interval, atrioventricular node (AVN), and atrial, ventricular, and accessory pathway effective refractory periods) changed significantly between the two different protocols. In pediatric patients undergoing EPS before ablation of SVT, remifentanil appears to slow both sinus and AV nodal function. These effects should be taken into consideration when performing EPS.

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.

Procedural sedation for children with special health care needs

Children with special health care needs represent a growing percentage of pediatric patients treated in all emergency departments. Substantial literature exists concerning the medical treatment of these patients, but there is little written describing the management of procedural sedation or analgesia in this population. This article examines the unique anatomic and physiologic implications of procedural sedation or analgesia management in children with special health care needs.

Flumazenil is innocuous in a paroxysmal supraventricular tachycardia and radiofrequency ablation: a paediatric case report and review of the literature

The efficacy and safety of flumazenil in reversing midazolam-induced paradoxical reaction in a child suffering from paroxysmal supraventricular tachycardia (PSVT) and undergoing radiofrequency ablation procedure has not been described before. We report a boy who had suffered for years from poorly controlled PSVT because of noncompliance to medications and was being sedated by midazolam and morphine (4 mg each) and prepared for radiofrequency ablation when he began attempting to speak, writhing and flailing his arms, for which physical restraint was required. We also review the current knowledge on the subject. Two doses of flumazenil 0.05 mg i.v. swiftly halted the untoward episode. The child opened his eyes and was calm, coherent and able to answer simple questions. All haemodynamic and respiratory parameters remained stable throughout this event, except for a temporary increase in heart rate (from 68 to 83 b x min-1). The aberrant behaviour did not resume when he was allowed to fall asleep during the ablation of a concealed left lateral accessory pathway. After that procedure, he awoke calm and pain free with no recollection of the aggressive episode. He was kept for 24 h in an intermediate cardiac care unit and was then discharged home. This apparent first report on the efficacious use of flumazenil for the reversal of a paradoxical reaction to midazolam during an electrophysiological study suggests that it neither induces abnormal heart rate nor interferes with the electrophysiological study or the ablation procedure.

Management of paediatric patients undergoing diagnostic and invasive cardiology procedures

Since diagnostic cardiac catheterization in children with congenital heart disease was first reported in 1947, echocardiography has been used as a non-invasive diagnostic tool in congenital heart disease, resulting in a decrease in diagnostic cardiac catheterizations. However, the total number of cardiac catheterizations remained at a steady level until the mid-1980s and has since increased progressively. This is a result of the introduction of interventional transcatheter techniques to improve or correct congenital heart malformations. Since the first description of balloon atrial septostomy, the range of indications for such techniques has steadily increased, particularly in the past 15 years. 'Deep' sedation or general anaesthesia is essential for the conduct of cardiac catheterization in children, particularly in the younger age group.