Double Ventricular Response with Aberrant Conduction Leading to Ventricular Dysfunction.

Double ventricular response (DVR), where a single P wave results in two QRS complexes, is a rare presentation of dual AV node physiology. It has been associated with ventricular dysfunction in the setting of incessant tachycardia. We present the case of an otherwise healthy adolescent who had frequent DVR without tachycardia leading to left ventricular dysfunction. Slow pathway modification led to a significant reduction in ectopy and normalization of ventricular function. This highlights that DVR without tachycardia might lead to ventricular dysfunction in pediatric patients. Slow pathway modification with reduction of ectopy may be sufficient to restore ventricular function.

High-density "APLE" Mapping-Activation, Propagation, Low Voltage, and Electrogram Evaluation with the HD Grid for Atrioventricular Nodal Re-entry Tachycardia Ablation.

This is the first case series to evaluate high-density mapping of the triangle of Koch (TOK) using the HD Grid to guide slow-pathway ablation integrating activation, propagation (with wave collision), low-voltage signals, and atrial electrogram appearance. We will describe our technique and the results in this case series. Using three-dimensional mapping and the HD Grid, patients underwent high-density voltage mapping of the TOK. Ablation site selection was based on properties during sinus rhythm with late activation, at or above the propagation wave collision, over low voltage, and with appropriate electrogram appearance. Five patients underwent mapping of the slow pathway using the HD Grid. Their median age was 14 years, their median weight was 54.1 kg, and their median height was 161.5 cm. The TOK was mapped with the HD Grid for a median of 3 min. The procedure was successful in all patients using this technique. The median lesion number to the site of success was 3, with a median total number of cryotherapy lesions of 11. No radiation was used. There were no recurrences. Using activation, propagation wave, low voltage, and electrogram appearance when mapping for slow-pathway localization and ablation with the HD Grid can be successful, results in high-density maps, and is relatively faster.

Voltage and propagation mapping: New tools to improve successful ablation of atrioventricular nodal reentry tachycardia.

INTRODUCTION: Mapping system is useful in ablation of atrioventricular nodal reentry tachycardia (AVNRT) and localization of anatomic variances. Voltage mapping identifies a low voltage area in the Koch triangle called low-voltage-bridge (LVB); propagation mapping identifies the collision point (CP) of atrial wavefront convergence. We conducted a prospective study to evaluate the relationship between LVB and CP with successful site of ablation and identify standard value for LVB. MATERIALS AND METHODS: Three-dimensional (3D) maps of the right atria were constructed from intracardiac recordings using the ablation catheter. Cut-off values on voltage map were adjusted until LVB was observed. On propagation map, atrial wavefronts during sinus rhythm collide in the site representing CP, indicating the area of slow pathway conduction. Ablation site was selected targeting LVB and CP site, confirmed by anatomic position on fluoroscopy and atrioventricular ratio. RESULTS: Twenty-seven consecutive patients were included. LVB and CP were present in all patients. Postprocedural evaluation identified standard cut-off of 0.3-1 mV useful for LVB identification. An overlap between LVB and CP was observed in 23 (85%) patients. Procedure success was achieved in all patient with effective site at first application in 22 (81%) patients. There was a significant correlation between LVB, CP, and the site of effective ablation (p = .001). CONCLUSION: We found correlation between LVB and CP with the site of effective ablation, identifying a voltage range useful for standardized LVB identification. These techniques could be useful to identify ablation site and minimize radiation exposure.

The underrecognized and neglected compact atrioventricular nodal potential: clinical significance for preventing atrioventricular block during so-called slow pathway radiofrequency ablation.

BACKGROUND: The radiofrequency (RF) ablation target may be located at the compact atrioventricular node (AVN) region during so-called slow pathway (SP) RF ablation, potentially leading to transient or permanent atrioventricular block (AVB). However, related data are rare. METHODS: Among 715 index consecutive patients who underwent RF ablation for atrioventricular nodal re-entry tachycardia, 17 patients subsequently experienced transient or permanent AVB and were included in this retrospective observational study. RESULTS: Among the 17 patients, two patients (11.8%) developed transient first-degree AVB, four patients (23.5%) developed transient second-degree AVB, seven patients (41.2%) developed transient third-degree AVB, and four patients (23.5%) developed permanent third-degree AVB. During baseline sinus rhythm before the start of RF ablation, no His-bundle potential was recorded from the RF ablation catheter. During the so-called SP RF ablation that led to transient or permanent AVB, junctional rhythm with ventriculoatrial (VA) conduction block followed by subsequent AVB was observed in 14 of 17 patients (82.4%), and a low-amplitude, low-frequency hump-shaped atrial potential was recorded before the start of RF ablation in 7 of the 17 patients (41.2%). Direct AVB occurred in 3 of the 17 patients (17.6%), and a low-amplitude, low-frequency hump-shaped atrial potential was recorded before the start of RF ablation in all 3 patients. CONCLUSIONS: The low-amplitude, low-frequency hump-shaped atrial potential recorded at the so-called SP region may reflect the electrogram of compact AVN activation, and RF ablation to this site heralds impending AVB even when a His-bundle potential is not recorded.

Atrioventricular nodal reentry tachycardia treatment using CARTO 3 V7 activation mapping: a new era of slow pathway radiofrequency ablation is under coming.

Background: Slow pathway (SP) ablation is the cornerstone for atrioventricular nodal reentry tachycardia (AVNRT) treatment, and a low-voltage bridge offers a good target during mapping using low x-ray exposure. We aimed to assess a new tool to identify SP by activation mapping using the last CARTO3® version, i.e., CARTO PRIME® V7 (Biosense Webster, Diamond Bar, CA, USA). Methods and results: Right atrial septum and triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3® procedure. In 60 patients (mean age 60.3 ± 14.7, 61% females) undergoing ablation for AVNRT, an automatic activation map using a DECANAV® mapping catheter and CARTO® Confidense™, Coherent, and FAM DX software modules were obtained. The SP was identified in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) in that region elicited junctional beats. The mean procedural time was 150.3 ± 48.3 min, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2. The mean number of RF applications was 3.9 ± 2, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure, and no AVNRT recurrences occurred during a mean follow-up of 14.3 ± 8.3 months. Conclusion: Ablation of the SP by automatic mapping using Confidense™, Coherent, and FAM DX software modules is an innovative, safe, and effective approach to AVNRT ablation. The CARTO3® V7 system shows on a 3D map the latest AV node activation area during sinus rhythm allowing low fluoroscopy time and highly effective RFCA.

Long-Term Follow-Up of Empirical Slow Pathway Ablation in Pediatric and Adult Patients with Suspected AV Nodal Reentrant Tachycardia.

BACKGROUND: The aim of this study was to assess long-term efficacy and safety of empirical slow pathway (ESP) ablation in pediatric and adult patients with a special interest in patients without dual AV nodal physiology (DAVNP). METHODS: A retrospective single-center review of patients who underwent ESP ablation between December 2014 and September 2022 was performed. Follow-up included telephone communication, letter questionnaire and outpatient presentation. Recurrence was based on typical symptoms. RESULTS: 115 patients aged 6-81 years (median age 36.3 years, 59.1% female; 26 pts < 18 years) were included. A typical history was present in all patients (100%), an ECG documentation of narrow complex tachycardia in 97 patients (84%). Patients were divided into three groups: Group 1 without DAVNP (n = 23), Group 2 with AH jump (n = 30) and Group 3 with AH jump and at least one AV nodal echo beat (n = 62). No permanent AV block was observed. During a median follow-up of 23.6 ± 22.7 months, symptom recurrence occurred in 7/115 patients (6.1%) with no significant difference between the groups (p = 0.73, log-rank test). Symptom recurrence occurred significantly more often in patients without (5/18 patients; 27%) as compared to patients with ECG documentation (2/97 patients; 2.1%; p = 0.025). No correlation between age and success rate was found (p > 0.1). CONCLUSIONS: ESP ablation is effective and safe in patients with non-inducible AVNRT. Overall, recurrence of symptoms during long-term follow-up is low, even if no DAVNP is present. Tachycardia documentation before the EP study leads to a significantly lower recurrence rate following ESP ablation.

Comportamiento del tiempo de conducción retrógrada al momento de la inducción de las taquicardias supraventriculares y su rol en el diagnóstico diferencial / Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

RESUMEN Antecedentes : El diagnóstico diferencial entre la taquicardia reentrante ortodrómica (TRO) y la taquicardia por reentrada nodal atípica (TRNa) puede ser dificultoso. Nuestra hipótesis es que las TRNa tienen más variabilidad en el tiempo de con ducción retrógrada al comienzo de la taquicardia que las TRO. Nuestros objetivos fueron evaluar la variabilidad en el tiempo de conducción retrógrada al inicio de la taquicardia en TRNa y TRO, y proponer una nueva herramienta diagnóstica para diferenciar estas dos arritmias. Métodos : Se midió el intervalo ventrículo-auricular (VA) de los primeros latidos tras la inducción de la taquicardia, hasta su estabilización. La diferencia entre el intervalo VA máximo y el mínimo se definió como delta VA (ΔVA). También contamos el número de latidos necesarios para que se estabilice el intervalo VA. Se excluyeron las taquicardias auriculares. Resultados : Se incluyeron 101 pacientes. Se diagnosticó TRO en 64 pacientes y TRNa en 37. El ΔVA fue 0 (rango intercuartílico, RIC, 0-5) milisegundos (ms) en la TRO frente a 40 (21-55) ms en la TRNa (p < 0,001). El intervalo VA se estabilizó significativamente antes en la TRO (1,5 [1-3] latidos) que en la TRNa (5 [4-7] latidos; p < 0,001). Un ΔVA < 10 ms diagnosticó TRO con 100% de sensibilidad, especificidad y valores predictivos positivo y negativo. La estabilización del intervalo VA en menos de 3 latidos predijo TRO con buena precisión diagnóstica. Los resultados fueron similares considerando sólo vías accesorias septales. Las TRN típicas tuvieron una variación intermedia. Conclusión : Un ΔVA < 10 ms es un criterio simple, que distingue con precisión la TRO de la TRNa, independientemente de la localización de la vía accesoria.

ABSTRACT Background : Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachy cardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives : The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods : The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results : In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p <0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p<0.001). A ΔVA <10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion : Presence of DVA <10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Pathophysiology and treatment of adults with arrhythmias in the emergency department, part 1: Atrial arrhythmias.

PURPOSE: This article, the first in a 2-part review, aims to reinforce current literature on the pathophysiology of cardiac arrhythmias and various evidence-based treatment approaches and clinical considerations in the acute care setting. Part 1 of this series focuses on atrial arrhythmias. SUMMARY: Arrhythmias are prevalent throughout the world and a common presenting condition in the emergency department (ED) setting. Atrial fibrillation (AF) is the most common arrhythmia worldwide and expected to increase in prevalence. Treatment approaches have evolved over time with advances in catheter-directed ablation. Based on historic trials, heart rate control has been the long-standing accepted outpatient treatment modality for AF, but the use of antiarrhythmics is often still indicated for AF in the acute setting, and ED pharmacists should be prepared and poised to help in AF management. Other atrial arrhythmias include atrial flutter (AFL), atrioventricular nodal reentry tachycardia (AVNRT), and atrioventricular reentrant tachycardia (AVRT), which warrant distinction due to their unique pathophysiology and because each requires a different approach to utilization of antiarrhythmics. Atrial arrhythmias are typically associated with greater hemodynamic stability than ventricular arrhythmias but still require nuanced management according to patient subset and risk factors. Since antiarrhythmics can also be proarrhythmic, they may destabilize the patient due to adverse effects, many of which are the focus of black-box label warnings that can be overreaching and limit treatment options. Electrical cardioversion for atrial arrhythmias is generally successful and, depending on the setting and/or hemodynamics, often indicated. CONCLUSION: Atrial arrhythmias arise from a variety of mechanisms, and appropriate treatment depends on various factors. A firm understanding of physiological and pharmacological concepts serves as a foundation for exploring evidence supporting agents, indications, and adverse effects in order to provide appropriate care for patients.

Evaluation of the effects of isoproterenol on arrhythmia recurrence following catheter ablation in patients with atrioventricular nodal re-entrant tachycardia: A randomized controlled clinical trial.

We aimed to determine the effects of isoproterenol on arrhythmia recurrence in atrioventricular nodal re-entrant tachycardia (AVNRT) patients treated with catheter ablation. The present randomized controlled clinical trial was conducted on AVNRT patients candidates for radiofrequency ablation (RFA). The patients were randomly assigned to receive isoproterenol (0.5-4 µg/min) or not (control group) for arrhythmia re-induction after ablation. The results of the electrophysiological (EP) study, the ablation parameters, and the arrhythmia recurrence rate were recorded. We evaluated 206 patients (53 males and 153 females) with a mean (SD) age of 49.87 (15.5) years in two groups of isoproterenol (n = 103) and control (n = 103). No statistically significant difference was observed between the two studied groups in age, gender, EP study, and ablation parameters. The success rate of ablation was 100% in both groups. During ~16.5 months of follow-up, one patient (1%) in the isoproterenol group and four patients (3.8%) in the control group experienced AVNRT recurrence (HR = 0.245; 95% confidence interval [CI], 0.043-1.418; p = .173). Based on the Kaplan-Meier analysis, there was no significant difference in the incidence rate of arrhythmia recurrence during the follow-up period between the two studied groups (p = .129). Additionally, there were no significant differences between the arrhythmia's recurrence according to age, gender, junctional rhythm, type of AVNRT arrhythmia, and DAVN persistence after ablation. Although isoproterenol administration for arrhythmia re-induction after ablation did not alleviate the treatment outcomes and arrhythmia recurrence following RFA in AVNRT patients, further studies with a larger sample size and a longer duration of follow-up are necessary.

Junctional Tachycardia: A Critical Reassessment.

Junctional tachycardia (JT) is typically considered to have an automatic mechanism originating from the distal atrioventricular node. When there is 1:1 retrograde conduction via the fast pathway, JT would resemble the typical form of atrioventricular nodal re-entrant tachycardia (AVNRT). Atrial pacing maneuvers have been proposed to exclude AVNRT and suggest a diagnosis of JT. However, after excluding AVNRT, one should consider the possibility of an infra-atrial narrow QRS re-entrant tachycardia, which can exhibit features that resemble AVNRT as well as JT. Pacing maneuvers and mapping techniques should be performed to assess for infra-atrial re-entrant tachycardia before concluding that JT is the mechanism of a narrow QRS tachycardia. Distinguishing JT from typical AVNRT or infra-atrial re-entrant tachycardia has notable implications regarding the approach to ablation of the tachycardia. Ultimately, a contemporary review of the evidence on JT raises some questions as to the mechanism and source of what has traditionally been considered JT.

Pseudo-Kussmaul's Sign in Atrioventricular Nodal Reentry Tachycardia: A Prospective, Cohort Study.

Aims: To study the respiratory variation of right atrial (RA) pressures at baseline and during atrioventricular nodal reentry tachycardia (AVNRT). Methods: Of the 23 patients screened, 16 participants with typical AVNRT were included in the study. After ensuring adequate hydration, baseline RA pressures were measured as the height of 'a' and 'v' waves. The patients were asked to take deep breaths, and the measurements were taken in both inspiration and expiration. Results: Of the 16 participants, 14(87.5%) showed a normal fall in the height of 'a' and 'v' waves with inspiration, 1(6.25%) showed no change and 1(6.25%) showed a rise in height at baseline, p <0.01. During induced AVNRT, the 'a' and 'v' wave heights increased in 8(50%), remained same in 6(37.5%) and showed a normal fall in 2(12.5%), p = 0.07 for 'a' waves and p = 0.09 for 'v' waves. When the magnitude and direction of change in 'a' and 'v' wave height at baseline was compared with AVNRT, it showed a significant difference with 13(81.25%) participants demonstrating positive Pseudo-Kussmaul's sign, p <0.01. Mean age was numerically higher in those with a more considerable inspiratory rise in RA pressures but was not statistically significant, χ2(2) = 3.1, p = 0.21. Conclusions: Pseudo-Kussmaul's sign does occur in a substantial number of patients during AVNRT. Clinical appreciation of this phenomenon is possible in half to three-fourth of patients, provided the mean RA pressures are low enough for the variation to be visible in the neck.

AVNRT cryoablation in children <26 kg: efficacy and safety of electrophysiologically guided low-voltage bridge strategy.

The recently published "electrophysiologically guided low-voltage bridge (LVB) strategy" is effective in the ablation of atrioventricular nodal re-entry tachycardia (AVNRT) in children. This study aimed to evaluate its efficacy and safety in children <26 kgs. Fourteen children [64% males, median age 6.5 years (IQR 6-8 years), median weight 25.5 kg (IQR 24-26 kg)] with AVNRT were treated. In all patients, we detected a LVB associated to a typical slow pathway potential. The acute success rate was 100% with a mean of 5.5 cryoablation deliveries. All procedures were performed with near-zero fluoroscopic exposure (median time 0.15 min, IQR 0-0.7 min), in six patients fluoroscopy was 0 min. There were no complications or recurrences during the follow-up (median 20.91 months, IQR 11.7-26.7 months).

[Supraventricular tachycardia]. / Supraventrikuläre Tachykardien.

Supraventricular tachycardia is a common occurrence in routine clinical practice. As a physician, one can encounter them everywhere, whether as a general practitioner or as an emergency doctor in a hospital. Some tachycardias might have robbed an on-call doctor the night or the last nerve; however, supraventricular tachycardia is usually a benign condition that is easily treatable and, in many cases, even curable. This article covers the differential diagnoses of supraventricular tachycardia and its treatment options. Atrial fibrillation, also a supraventricular tachycardia, is not discussed in this article.

Distinctive characteristics of His bundle potentials in patients with atrioventricular nodal reentrant tachycardia.

BACKGROUND: His bundle (HB) potentials vary in amplitude and duration in patients with and without slow pathways. The aim of this study was to determine the characteristics of HB potentials and to elucidate whether they can provide clues for identification of slow pathway (SP). METHODS: The present research prospectively studied the electrophysiological findings of 162 patients with symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) due to slow-fast or fast-slow type and atrioventricular reentrant tachycardia (AVRT). Maximal HB potential (HBmax, HB with the highest amplitude) among HB cloud was recorded in both groups. For AVNRT patients, the following were measured: (1) AH interval at the "jump" during programmed atrial stimulation (A2H2, taken as a reflection of SP conduction time); (2) Distance from HBmax to the successful SP ablation site (HBmax-ABL) and from HBmax to the ostium of coronary sinus (HBmax-CSO). RESULTS: HBmax was 0.29 ± 0.10 mV in AVNRT patients, whereas it was 0.17 ± 0.05 mV in AVRT group (p < 0.0001). Likewise, the HBmax duration was 22 ± 5 ms in AVNRT group and 16 ± 3 ms in AVRT group (p < 0.0001). The area under the receiver operating characteristic curve of HBmax amplitude in AVNRT patients was 0.86 and the optimal HBmax cut-off to predict AVNRT was ≥ 0.22 mV with a sensitivity of 0.78 and specificity of 0.84. HBmax-CSO was positively correlated with HBmax-ABL, and HBmax-ABL was positively correlated with A2H2. CONCLUSIONS: HBmax amplitudes were higher and durations longer in patients with AVNRT, as compared to those with AVRT. Moreover, the distance between HBmax and successful ablation site was positively correlated with the SP conduction time and with the distance from HBmax to the CSO.

Efficacy and safety of zero-fluoroscopy approach for ablation of atrioventricular nodal reentry tachycardia: experience from more than 1000 cases.

BACKGROUND: Radiofrequency catheter ablation (RFCA) of the slow pathway in atrioventricular nodal reentry tachycardia (AVNRT) is associated with high efficacy and low risk of total perioperative or late atrioventricular block. This study aimed to evaluate the efficacy, safety, and feasibility of slow-pathway RFCA for AVNRT using a zero-fluoroscopy approach. METHODS: Data were obtained from a prospective multicenter registry of catheter ablation from January 2012 to February 2018. Consecutive unselected patients with the final diagnosis of AVNRT were recruited. Electrophysiological and 3-dimensional (3D) electroanatomical mapping systems were used to create 3D maps and to navigate only 2 catheters from the femoral access. Acute procedural efficacy was evaluated using the isoproterenol and/or atropine test, with 15-min observation after ablation. Each case of recurrence or complication was consulted at an outpatient clinic during long-term follow-up. RESULTS: Of the 1032 procedures, 1007 (97.5%) were completed without fluoroscopy. Conversion to fluoroscopy was required in 25 patients (2.5%), mainly due to an atypical location of the coronary sinus (n = 7) and catheter instability (n = 7). The mean radiation exposure time was 1.95 ± 1.3 min for these cases. The mean fluoroscopy time for the entire study cohort was 0.05 ± 0.4 min. The mean total procedure time was 44.8 ± 18.6 min. There were no significant in-hospital complications. The total success rate was 96.1% (n = 992), and the recurrence rate was 3.9% (n = 40). CONCLUSION: Slow-pathway RFCA can be safely performed without fluoroscopy, with a minimal risk of complications and a high success rate.

Narrow Complex Tachycardia With Intermittent 2:1 Atrioventricular Relationship.

Narrow QRS complex tachycardia has a broad differential diagnosis. We present a series of rhythm strips with representative onset, transition from 2:1 AV conduction to 1:1 AV conduction, and offset of tachycardia. By analyzing these rhythm strips, we can identify the electrophysiologic mechanism and diagnosis. (Level of Difficulty: Intermediate.).

Taquicardia supraventricular sostenida tras inducción anestésica inhalatoria con sevoflurano en paciente pediátrico / Persistent supraventricular tachycardia after volatile inhalational anaesthetic induction with sevoflurane in a pediatric patient

La inducción anestésica inhalatoria con sevoflurano es muy empleada en la población pediátrica. Si bien los efectos sistémicos más comunes son ampliamente conocidos, no se conocen todos los efectos secundarios de este fármaco. Presentamos el caso clínico de un varón de cuatro años que desarrolló un episodio de taquicardia supraventricular sostenida tras la inducción anestésica con sevoflurano, que no cedió hasta que no se retiró el fármaco y se sustituyó el mantenimiento anestésico por una perfusión continua de fármacos hipnóticos intravenosos (propofol y remifentanilo). Desconocemos el mecanismo exacto por el que este episodio ha tenido una relación causal tan clara con la administración de sevoflurano; las posibilidades diagnósticas serían la taquicardia por reentrada intranodal o la existencia de una vía accesoria. No hemos encontrado en la literatura un episodio de taquicardia supraventricular mantenida con una relación causal directa con la administración de sevoflurano como en el caso que presentamos.(AU)

Inhaled anaesthetic induction with sevoflurane is very common in the pediatric population. Sevoflurane systemic effects are widely known, while not all the side effects are known. We present a four year-old child who developed a persistent supraventricular tachycardia af-ter inhaled anaesthetic induction with sevoflurane. The arrhythmia did not end until sevoflurane was stopped and changed to an intravenous continuous perfusion ofhypnotic drugs (propofol and remiphentanyl). The exact mechanism for such a causal relationship with sevoflurane administration is unknown, and possible diagnoses include atrioventricular nodal reentry tachycardia (AVNRT) and the existence of an accessory pathway. An episode of persistent supraventricular tachycardia with a clear causal relationship with sevoflurane administration is not found in the literature.(AU)