Atrioventricular Reentry Tachycardia Research Articles

Common Supraventricular and Ventricular Arrhythmias in Children.

The most common pediatric arrhythmias are tachycardias, and the most common type is supraventricular tachycardia, originating from or above the atrioventricular node and HIS bundle. Ventricular tachycardias are less common but more dangerous. Supraventricular tachycardias usually cause a narrow complex tachycardia unless there is a basal bundle branch block or rate-dependent aberration. A wide QRS tachycardia should be treated as ventricular tachycardias unless proven to be an supraventricular tachycardia with aberration. Diagnosis of both tachyarrhythmia types depends mainly on 12-lead electrocardiography. The most common supraventricular tachycardia type in newborns and infants is atrioventricular reentry tachycardia, related to manifest or concealed accessory pathways and in adolescent atrioventricular nodal reentry tachycardia, whereas focal atrial tachycardias consist of 10%-15% of supraventricular tachycardias during all ages. Supraventricular tachycardias have a low risk of morbidity, and ablation therapy is successful in most types with success rates over 90%. Ventricular tachycardias can be monomorphic or polymorphic, nonsustained or sustained, and can cause more hemodynamic instability than supraventricular tachycardias, requiring more close monitoring and urgent therapies. If hemodynamically unstable, synchronized cardioversion must be performed. Polymorphic ventricular tachycardias are very dangerous and often associated with primary ion channel defects (channelopathies), which can cause sudden cardiac death.

Randomized comparison of atrioventricular node re-entry tachycardia and atrial flutter catheter ablation with and without fluoroscopic guidance: ZeroFluoro study.

Interventional cardiology procedures may expose patients and staff to considerable radiation doses. We aimed to assess whether exposure to ionizing radiation during catheter ablation of supraventricular tachycardia (SVT) can be completely avoided. In this prospective randomized study, patients with SVT (atrioventricular re-entrant tachycardia n = 94, typical atrial flutter n = 29) were randomly assigned in a 1:1 ratio to catheter ablation with conventional fluoroscopic guidance (CF group) or with the EnSite Precision mapping system [zerofluoro (ZF) group]. Acute procedural parameters, increased stochastic risk of cancer incidence and 6-month follow-up data were assessed. Between May 2019 and August 2020, 123 patients were enrolled. Clinical parameters were comparable. Median procedural time was 60.0 and 58.0 min, median fluoroscopy time and estimated median effective dose were 240 s vs. 0 and 0.38 mSv vs. 0 and arrhythmia recurrence was 5% and 7.9% in the CF and ZF groups, respectively. The acute success rate was 98.4% in both groups. No procedure-related complications were reported. At an average age of 55.5 years and median radiation exposure of 0.38 mSv, the estimate of increased incidence was approximately 1 in 14 084. The estimated mortality rate was 1 per 17 857 exposed persons. The procedural safety and efficacy of the zero-fluoroscopic approach are similar to those of conventional fluoroscopy-based ablation for atrioventricular nodal re-entrant tachycardia and atrial flutter. Under the assumption of low radiation dose, the excessive lifetime risk of malignancy in the CF group due to electrophysiology procedure is reasonably small, whilst totally reduced in zero fluoroscopy procedures.

Deep-Learning-Based Detection of Paroxysmal Supraventricular Tachycardia Using Sinus-Rhythm Electrocardiograms.

Background: Paroxysmal supraventricular tachycardia (PSVT) is a common arrhythmia associated with palpitation and a decline in quality of life. However, it is undetectable with sinus-rhythmic ECGs when patients are not in the symptomatic onset stage. Methods: In the current study, a convolution neural network (CNN) was trained with normal-sinus-rhythm standard 12-lead electrocardiographs (ECGs) of negative control patients and PSVT patients to identify patients with unrecognized PSVT. PSVT refers to atrioventricular nodal reentry tachycardia or atrioventricular reentry tachycardia based on a concealed accessory pathway as confirmed by electrophysiological procedure. Negative control group data were obtained from 5107 patients with at least one normal sinus-rhythmic ECG without any palpitation symptoms. All ECGs were randomly allocated to the training, validation and testing datasets in a 7:1:2 ratio. Model performance was evaluated on the testing dataset through F1 score, overall accuracy, area under the curve, sensitivity, specificity and precision. Results: We retrospectively enrolled 407 sinus-rhythm ECGs of PSVT procedural patients and 1794 ECGs of control patients. A total of 2201 ECGs were randomly divided into training (n = 1541), validation (n = 220) and testing (n = 440) datasets. In the testing dataset, the CNN algorithm showed an overall accuracy of 95.5%, sensitivity of 90.2%, specificity of 96.6% and precision of 86.0%. Conclusion: Our study reveals that a well-trained CNN algorithm may be a rapid, effective, inexpensive and reliable method to contribute to the detection of PSVT.

The Risk of Sudden Death Associated with Symptomatic and Asymptomatic Ventricular Pre-excitation in Athletes

Abstract Sudden death (SD) in athletes is a potential avoidable dramatic scenario. When done regularly, cardiological evaluation increases the chances of diagnosing ventricular pre-excitation. Consequently, the following question arises: what is the real incidence of SD risk in athletes with Wolff-Parkinson-White (WPW) syndrome/pattern? This study included 84 consecutive patients diagnosed with WPW and was designed as a retrospective analysis of data acquired between 2011 and 2021 to answer this question. The patients were evaluated using a 12-lead electrocardiogram (ECG), echocardiography, stress test, and electrophysiological study (EPS). The SD risk linked to WPW was defined as ≥ 1 of the following: the anterograde effective refractory period (AERP) of the accessory pathway (AP) ≤ 250 ms, atrial fibrillation (AF) with the shortest RR pre-excited interval ≤ 250 ms, syncope during AF or atrioventricular reentry tachycardia. The athletes with WPW pattern (n=25) or syndrome (n=59) at risk of SD were identified and treated with radiofrequency ablation (RFA). The mean age was 19.83 (10–29) years; 66.6% were men. Seventeen athletes (n=17; 20.23%) were found with SD risk: 15 (n=15; 17.85%) in the WPW syndrome group and 2 (n=2; 2.38%) in the WPW pattern group. During the EPS, n=4 developed syncope: 1 during antidromic tachycardia and 3 during pre-excited AF. RFA was curative in 96.42% of cases. The EPS is mandatory to identify athletes with short AERP APs linked to an increased risk of SD. RFA is the intervention that settles the patients into a risk-free area, allowing resumption of sports shortly afterward.

Zero-fluoroscopy catheter ablation of supraventricular tachycardias in pediatric population

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation (CA) of supraventricular tachycardias (SVTs) in pediatric patients is conventionally performed with the aid of X-ray fluoroscopy. Usage of the three-dimensional (3D) electro-anatomical mapping (EAM) system and the intracardiac echocardiography (ICE) enables zero-fluorscopy ablation, eliminating the harmful effects of the radiation (1-3). Purpose We retrospectively analyzed the feasibility, effectiveness and safety of zero-fluoroscopy radiofrequency and cryoablation of various types of SVTs in pediatric patients. Methods In this retrospective study, we analyzed consecutive pediatric patients who underwent CA procedure due to SVT in our institution from April 2014 to October 2021. All procedures were performed completely without the use of fluoroscopy. A 3D EAM system and ICE were used as the principal modes of catheter visualisation. Left-sided procedures were done with ICE guided transseptal approach. Radiofrequency was the principal energy source, while cryoablation was used for arrhythmia substrates in the proximity of the conduction system. Results The study included 174 consecutive patients (69/174 (66%) female; 12.5 ± 3.9 years; 19.2 ± 3.6 kg/m2). Altogether 176 SVTs were diagnosed and treated. Atrio-ventricular nodal reentry tachycardia (AVNRT) was diagnosed in 45% of cases (80/176), atrio-ventricular reentry tachycardia (AVRT) in 47% (82/176), focal atrial tachycardia (AT) in 7% (13/176), typical atrial flutter (AFL) was treated in only one patient, while 2 patients had multiple arrhythmias (AVNRT and AVRT). In total, 202 procedures were performed. Radiofrequency ablation was performed in 76% (154/202), cryoablation in 20% (40/202) and both in 4% (8/202) of procedures. The acute procedural success rate was 96% (195/202). Procedural success rate was 99% (79/80) for AVNRT, 94% (77/82) for AVRT, 92% (12/13) for AT, and 100% (1/1) for AFL, respectively. There were no major complications in our study group. Follow-up was complete in 99% (172/174) of patients. During the follow-up period of a median of 316 days (181 - 747), 98% of patients were arrhythmia free. On average, 1.16 procedures per patient were performed with the long-term success rate of 99% (79/80), 98% (80/82), 100% (13/13) and 100% (1) for AVNRT, AVRT, AT, and AFL, respectively. Conclusion Zero-fluoroscopy CA of various types of SVTs in pediatric population is a feasible, effective, and safe treatment option.

Health care centre and emergency department utilization by patients with episodes of tachycardia

BackgroundOutpatients seek to visit health care facilities for episodes of tachycardia-related signs and symptoms. The challenge for physicians is to balance a proper initial assessment and avoid overlooking a possible arrhythmia. This common clinical situation affects individuals and health care utilization, and effective management may substantially affect health care resources. This study aimed to explore health care utilization for outpatients with episodes of tachycardia visiting health care centres (HCCs) and/or emergency departments (EDs).MethodThis retrospective study used data of adult outpatients (≥ 18 years) who were assessed by a physician as having a specific or nonspecific diagnosis of arrhythmia between 2017 and 2018, and data were retrieved from medical records and a regional registry database. Data was analysed with appropriate statistical analyses to identify disparities between sex, age and terms of search pattern for each health care facility. Analysis of variance was used to test disparities between the sexes, and one-factor ANOVA was used for the incidence of missed arrhythmias.ResultsA total of 2719 visits with 2373 outpatients were included in the study. The result showed a significant difference in the total number of visits (n = 2719) between female and male patients (68% vs. 32%, p < .001). In the 60–69- and 70–79-year age groups, females had significantly higher frequencies of visits than males (p = .018). A significant difference was also observed between sexes in terms of which health care facility they tended to visit (p < .001). Ninety-five percent of the outpatients visiting EDs were hospitalized. When estimating the incidence of missed arrhythmias (diagnoses) in relation to assessments, the results showed a 5% missed diagnosis involving potential atrioventricular nodal re-entry tachycardia and atrioventricular re-entry tachycardia. Moreover, the referral rate was low, especially from HCCs to cardiologists.ConclusionsThis study shows a significant difference in total visits in HCCs and/or EDs by patients of different sexes and indicates the need for improved care for outpatients with episodes of tachycardia. Sex- and age-related differences must be addressed with an aim of providing equal care. Finally, the low rate of referral from HCCs to cardiologists compared to the high proportion of hospitalizations from EDs, deserves further investigation.

Miniseries 1-Part II: the comparative anatomy of the atrioventricular conduction axis.

The arrangement of the conduction axis is markedly different in various mammalian species. Knowledge of such variation may serve to question the validity of using animals as prospective models for design of systems for clinical use. We compared the arrangement of the atrioventricular conduction axis in human, murine, canine, porcine, and bovine hearts, examining serially sectioned datasets from 20 human, 16 murine, 3 porcine, 5 canine, and 1 bovine hearts. We also analysed computed tomographic datasets obtained from bovines and one human heart. Unlike the situation in the human heart, there is no formation of an atrioventricular fibrous membranous septum in the murine, canine, porcine, nor bovine hearts. Canine, porcine, and bovine hearts also lack an infero-septal recess, when defined as a fibrous plate supporting the buttress of the atrial septum. In these species, half of the non-coronary leaflet is directly opposed to the ventricular septal surface. There is a long right-sided non-branching component of the axis, which skirts the attachment of the non-coronary sinus of the aortic root. In the bovine heart, moreover, the left bundle branch usually extends intramyocardially as a solitary tape before surfacing and ramifying on the left ventricular septal surface. The difference in the atrioventricular conduction axis between species may influence the anatomical substrates for atrioventricular re-entry tachycardia, as well as providing inferences for assessing the risks of transcatheter implantation of the aortic valve. Further studies are now needed to assess these possibilities.

Outcomes of supraventricular tachycardia ablation: Results from the Singapore ablation and cardiac devices registry

AbstractBackgroundThe Singapore Cardiac Databank was designed to monitor the performance and outcomes of catheter ablation. We investigated the outcomes of paroxysmal supraventricular tachycardia (PSVT)‐ablation in a prospective, nationwide, cohort study.MethodsAtrioventricular nodal re‐entrant tachycardia (AVNRT), atrioventricular re‐entry tachycardia (AVRT), or atrial tachycardia (AT)‐ablations in Singapore from 2010 to 2018 were studied. Outcomes include acute success, periprocedural‐complications, postoperative pacing requirement, arrhythmic recurrence and 1‐year all‐cause mortality.ResultsAmong 2260 patients (mean age 45 ± 18 years, 50% female, 57% AVNRT, 37% AVRT, 6% AT), overall acute success rates of PSVT‐ablation was 98.4% and increased in order of AT, AVRT, and AVNRT (p &lt; .001). Periprocedural cardiac tamponade occurred in two AVRT patients. A total of 15 pacemakers (6 within first 30‐days, 9 after 30‐days) were implanted (seven AV block, eight sinus node dysfunction [SND]), with the highest incidence of pacemaker implantation after AT‐ablation (5% vs. 0.6% AVNRT vs. 0.1% AVRT, p &lt; .001). Repeat ablations (0.9% AVNRT, 7% AVRT, 4% AT, p &lt; .001) were performed in 78 (3.5%) patients and 13 (0.6%) patients died within a year of ablation. Among outcomes considered adjusting for age, sex, PSVT‐type and procedure‐time, AT was independently associated with 6‐fold increased odds of total (adjusted odds ratio [AOR] 6.32, 95% confidence interval [CI] 1.95–20.53) and late (AOR 6.38, 95% CI 1.39–29.29) pacemaker implantation, while AVRT was associated with higher arrhythmic recurrence with repeat ablations (AOR 4.72, 95% CI 2.36–9.44) compared to AVNRT.ConclusionsContemporary PSVT ablation is safe with high acute success rates. Long‐term outcomes differed by nature of the PSVT.

547 Supernormal conduction of an accessory pathway: the case of a young sportsman

Abstract Aims Ventricular pre-excitation is defined by the presence of all of the following electrocardiographic criteria: PQ interval duration ≤120 ms, QRS duration ≥120 ms, and presence of δ wave (defined as initial ‘slurring’ of the QRS complex). Ventricular pre-excitation together with the presence of symptoms (orthodromic and/or antidromic atrioventricular reentry tachycardia, atrial fibrillation) defines Wolff–Parkinson–White (WPW) syndrome. The anatomical substrate of ventricular pre-excitation consists of an extranodal accessory atrio-ventricular connection: the so-called Kent bundle. Such pathways can have antegrade, retrograde, or mixed conductive properties. Accessory pathways endowed with anterograde conductive capability may be responsible for manifest, intermittent, or non-manifest ventricular pre-excitation depending on whether it is respectively always visible on the ECG, not always visible on the ECG and not visible on the ECG even though the pathway has the ability to antegrade conduction. The rare phenomenon of supernormal conduction of anomalous pathways is part of the manifest pre-excitation, which represents the topic of the case reported below. Methods and results We report the clinical case of a young not agonist sportsman undergoing an electrophysiological study (SEF) because of he is suffering from ventricular pre-excitation. The SEF did not showed the inducibility of arrhythmias and, at the same time, apparently it showed low risk characteristics of the pathway even during adrenergic stimulus. However, a careful study, performed with atrial stimulation with couplings up to refractoriness of the atrioventricular node revealed supernormal conduction properties of the Kent bundle which proved to have high risk characteristics according to current guidelines and, therefore, was effectively treated with catheter ablation. Conclusions This case invites us to careful studying of accessory pathways properties, especially since, although rare, they may possess supernormal conduction characteristics capable of determining high ventricular rates in the case of sustained atrial tachyarrhythmias, especially in conditions of adrenergic hyperactivity.

Outcomes From Pediatric Ablation: A Review of 20 Years of National Data.

This study set out to examine outcomes from pediatric supraventricular tachycardia ablations over a 20-year period. This study sought to examine success rates and repeat ablations over time and to evaluate whether modalities such as 3-dimensional (3D) mapping, contact force, and cryotherapy have improved outcomes. Ablation of supraventricular tachycardia in pediatric patients is commonly performed in most congenital heart centers with excellent long-term results. Data were retrieved from the NICOR (National Institute of Clinical Outcomes Research) database in the United Kingdom. Outcomes over time were evaluated, and procedure-related details were compared. There were 7,069 ablations performed from January 1, 1999, to December 31, 2018, at 10 centers. Overall, ablation success rates were 92% for accessory pathways, 97% for atrioventricular node re-entry tachycardia, and 89% for atrial tachycardia. There was an improvement in procedural success rates over time (p<0.01). The use of 3D mapping did not alter success or need for repeat ablation but was associated with a higher proportion of lower fluoroscopy cases; 55% of 3D mapping cases used<5 min of fluoroscopy (p<0.01). Patients needing a repeat ablation were 341 (12%) for accessory pathways, 128 (7%) for atrioventricular node re-entry tachycardia, and 35 (7%) for atrial tachycardia. Overall, the risk of complete heart block was low (n = 12,<0.01%). The use of cryotherapy was associated with an increased risk of needing a repeat ablation. Overall success rates from pediatric ablations are excellent and compare favorably to other registries. Introduction of newer technologies have likely made procedures safer and reduced radiation exposure, but they have not changed success rates or the need for a repeat procedure.

Remote magnetic navigation shows superior long-term outcomes in pediatric atrioventricular (nodal) tachycardia ablation compared to manual radiofrequency and cryoablation.

BackgroundCatheter ablation (CA) is the first-choice treatment for tachyarrhythmia in children. Currently available CA techniques differ in mechanism of catheter navigation and energy sources. There are no large studies comparing long-term outcomes between available CA techniques in a pediatric population with atrioventricular reentry tachycardia (AVRT) or atrioventricular nodal reentry tachycardia (AVNRT) mechanisms.ObjectiveThis study aimed to compare procedural and long-term outcomes of remote magnetic navigation-guided radiofrequency (RF) ablation (RMN), manual-guided RF ablation (MAN) and manual-guided cryoablation (CRYO).MethodsThis single-center, retrospective study included all first consecutive CA procedures for AVRT or AVNRT performed in children without structural heart disease from 2008 to 2019. Three study groups were defined by the ablation technique used: RMN, MAN or CRYO. Primary outcome was long-term recurrence of tachyarrhythmia.ResultsIn total, we included 223 patients, aged 14 (IQR 12–16) years; weighting 56 (IQR 47–65) kilograms. In total, 108 procedures were performed using RMN, 76 using MAN and 39 using CRYO. RMN had significantly lower recurrence rates compared to MAN and CRYO at mean follow-up of 5.5 ± 2.9 years (AVRT: 4.3% versus 15.6% versus 54.5%, P < 0.001; AVNRT: 7.7% versus 8.3% versus 35.7%, P = 0.008; for RMN versus MAN versus CRYO respectively). In AVNRT ablation, RMN had significantly lower fluoroscopy doses compared to CRYO [30 (IQR 20–41) versus 45 (IQR 29–65) mGy, P = 0.040).ConclusionIn pediatric patients without structural heart disease who underwent their first AV(N)RT ablation, RMN has superior long-term outcomes compared to MAN and CRYO, in addition to favorable fluoroscopy doses.

Endocavitary electrophysiological study by percutaneous antecubital vein and without X-ray for risk stratification of asymptomatic ventricular pre-excitation in young athletes.

Athletes with asymptomatic ventricular pre-excitation (VP) should undergo electrophysiological study for risk stratification. We aimed to evaluate the feasibility, efficacy, safety and tolerability of an electrophysiological study using a percutaneous antecubital vein access and without the use of X-ray (ESnoXr). Methods: We collected data from all young athletes<18year-old with AVP, who underwent ESnoXr from January 2000 to September 2020 for evaluation of accessory pathway refractoriness and arrhythmia inducibility using an antecubital percutaneous venous access. Endocavitary signals were used to advance the catheter in the right atrium and ventricle. Results: We included 63 consecutive young athletes (mean age 14.6±1.9years, 46% male). Feasibility of the ESnoXr technique was 87% while in 13% fluoroscopy and/or a femoral approach were needed. Specifically, fluoroscopy was used in 7 cases to position the catheter inside the heart cavities with an average exposure of 43±38s while in 2 femoral venous access was needed. The mean procedural time was 35±11min. The exam was diagnostic in all patients, there were no procedural complications and tolerability was excellent. 53% of the patients had an accessory pathway with high refractoriness and no inducible atrio-ventricular reentry tachycardia: this subgroup was considered eligible to competitive sports and no event was observed during long-term follow-up (13.6±5.2years) without drug use. The others underwent catheter ablation. Conclusion. ESnoXr has been shown to be a feasible, effective, safe and well-tolerated procedure for the assessment of arrhythmic risk in a population of young athletes with asymptomatic VP.

Quality of Life after Ablation vs Medication Therapy in Patients With Supraventricular Tachycardia

Objective: Supraventricular tachycardia (SVT) is the most common presentation of patients at cardiac emergency department. This study aims to determine the quality of life in patients with supraventricular tachycardia after they treated with medicines vs. ablation therapy.&#x0D; Methods: This prospective clinical comparative study was held at the National Institute of Cardiovascular Diseases (NICVD). Patients 18 years or older of either gender presenting with the two most common variants of SVT i.e. Atrioventricular nodal reentry tachycardia (AVNRT) and Atrioventricular reentry tachycardia (AVRT) were eligible to be included into the study. Once stabilized at the emergency department (ED) the patients were given the option to undergo electrophysiology study and radiofrequency ablation (EPS and RFA) (group A) or opt for medications only (group B). Quality of life (sense of personal well being, impact on social life, fear of mortality or anxiety about the disease, recurrence of episodes of arrhythmia, and visits to ED) was assessed through a questionnaire filled after six months of receiving treatment.&#x0D; Results: A total of 120 patients were included into our study. Group A and group B were evenly divided with 60 patients each. The overall mean age of the participants and duration of cardiac illness were 44.67±18.91 and 5.42±3.13 years, respectively. Patients who received EPS and RFA (group A) had superior and statistically significant scores (better QoL) for sense of personal well being, impact on social life, fear of mortality or anxiety levels, recurrence of arrhythmia, and visits to the ED as compared to those who received medications alone, p&lt;0.05.&#x0D; Conclusion: EPS and RFA vastly improved the quality of life in patients with SVT post treatment. Medications alone are associated with a high number of post treatment sequels and adverse events; therefore they are best avoided in patients with SVT.

Beginning of Ventricular Entrainment for Differentiation Between AVNRT and AVRT

AbstractBackground: Differentiation between atrioventricular nodal reentry tachycardia (AVNRT) and accessory pathway-mediated atrioventricular reentrant tachycardia (AVRT) is challenging even during electrophysiological testing.Objective: To use the beginning of RV entrainment to differentiate between AVRT and AVNRT as an independent criterion with high sensitivity and specificity.Methods: We studied 50 patients with supra-ventricular tachycardia. RV pacing was performed 10-40ms faster than tachycardia. Once a fixed QRS morphology was observed in 12-leads ECG, we determined after which beat the atrial perpetuation had been achieved. Results: In all the 19 patients who had AVRT, atrial perpetuation occurred from the first beat. While, in all 31 cases of AVNRT atrial perpetuation occurred within the 2 beat or more. Conclusion: Analysing the beginning of ventricular entrainment can indeed differentiate between AVRT and AVNRT cases easily with a high positive predictive value.Keywords: Supra-ventricular tachycardia; Atrio-ventricular reentry tachycardia; AV Reentry tachycardia; Entrainment, Electrophysiological study, EP lab.

Remote magnetic navigation shows superior long-term outcomes in pediatric atrioventricular (nodal) tachycardia ablation compared to manual radiofrequency and cryoablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction – Catheter ablation (CA) is a first-choice treatment for tachyarrhythmia in pediatric patients. The currently available CA techniques differ in manner of catheter steering technique and energy sources. There are no large studies comparing long-term outcomes between the available CA techniques in pediatric patients with atrioventricular reentry (also known as accessory pathway mediated) tachycardia (AVRT) or atrioventricular nodal reentry tachycardia (AVNRT) mechanisms. Objective – The aim of this study was to compare procedural parameters and outcomes of remote magnetic navigation-guided radiofrequency (RF) ablation (RMN), manual-guided RF ablation (MAN) and manual-guided cryoablation (CRYO). Methods – This single-center, retrospective study included all first consecutive CA procedures for AVRT or AVNRT mechanisms performed in pediatric patients with no structural heart disease from January 2008 until June 2019. Three study groups were defined by the ablation technique used: RMN, MAN or CRYO. Primary outcome was recurrence of tachyarrhythmia and/or pre-excitation on ECG. Baseline clinical parameters, procedure times and complication rates were also evaluated. Results – In total, we included 223 patients, aged 13.8 ± 2.8 years, with a mean weight of 55.6 ± 14 kilograms. In total, 108 procedures were performed using RMN, 76 using MAN and 39 using Cryo. RMN had the lowest recurrence rates at a mean follow-up of 5.5 ± 2.9 years (AVRT ablation: 4% vs. 16% vs. 55%, P &amp;lt; 0.001; AVNRT ablation: 8% vs. 8% vs. 36%, P = 0.008; for RMN vs. MAN vs. CRYO respectively). In AVRT ablation, procedure and fluor times were comparable between groups. However, in AVNRT ablation, RMN and MAN had significantly lower fluoroscopy times compared to Cryo (10 (IQR 7-14) vs. 9 (IQR 6-26) vs. 15 (IQR 10-22) minutes respectively, P = 0.040). Moreover, procedure times were shortest in MAN and second in RMN ablation (101 (IQR 87-121) vs. 88 (IQR 62-99) vs. 120 (IQR 88-143) minutes respectively, P = 0.018). We observed minor complications in 3 patients (1%), which were comparable between groups and no major complications. Conclusion – In pediatric patients with no structural heart disease who underwent their first AV(N)RT ablation, RMN has the most favorable long-term outcomes, in addition to favorable fluoroscopy and procedure times. Abstract Figure. AVRT and AVNRT ablation recurrence rates

Low-fluoro workflows and impact in radiation exposure in the electrophysiology lab

Abstract Funding Acknowledgements Type of funding sources: None. Background During electrophysiology (EP) procedures, fluoroscopy imaging is employed to visualise catheters position in real-time. However, ionizing radiation is a health hazard to both the patient and operator. In recent years, the use of electroanatomical mapping systems and operator adoption of low-fluoro workflows has allowed a reduction of radiation exposure. The aim of this study was to assess the evolution of fluoroscopy time (FT) in EP procedures, using conventional technique or an electroanatomical mapping system (EMS). Methods A retrospective analysis of consecutive EP procedures performed at a tertiary centre between September 2018 and October 2020 was conducted. The procedures were divided in 3 tertiles according to date (T1, T2 and T3), with T3 corresponding to the most recent interventions. Procedural duration, FT, use of EMS, radiofrequency time (RT), acute ablation success and procedural complications were examined. Results A total of 615 procedures were analysed: atrioventricular node reentry tachycardia (AVNRT) – n = 144, accessory pathways (AP) – n = 83, typical atrial flutter – n = 106, atrial fibrillation (AF) ablation with radiofrequency (RF) – n = 61, AF ablation with cryoballoon – n = 92, ablation of ventricular arrhythmias – n = 53, and 75 miscellaneous procedures (including atrioventricular node ablation, left atrial flutter ablation and cardioneuroablation). Mean age was 54.6 ± 18.2 years with 59.4% male sex patients. An EMS was used in 75% of the procedures, without significant differences between tertiles. A progressive reduction in median FT was observed over the tertiles (T1 6.3 min, interquartile range [IQR] 2.9-13.6; T2 5.4 min, IQR 2.1-12.0, and T3 3.1 min, IQR 1.2-7.2, Figure 1), and a statistical significant difference was found when comparing T1 to T3 (p &amp;lt; 0.001) and T2 to T3 (p &amp;lt; 0.001). The decrease in FT was observed throughout the study period for all different EP procedures (Figure 2). The number of procedures with zero fluoroscopy had gradually increased (T1 6.1%, T2 8.5% and T3 14.1%; T1 vs. T3 p &amp;lt;0.01). Younger patients (&amp;lt;20 years) were submitted to low fluoroscopy doses with a significant decrease over tertiles (T1 1.2 min, IQR 0.0-4.3; T2 0.9 min, IQR 0.0-2.5; T3 0.0, IQR 0.0-2.2, T1 vs.T3 p &amp;lt; 0.001). No significant difference in procedural duration, RT, acute procedural success or complication rate were noted between tertiles. Conclusion Reduction in radiation exposure can be achieved without compromising duration, safety and effectiveness of the procedure. The commitment of operators to reduce radiation exposure using 3D mapping technology can lead to a significant decrease in the use of fluoroscopy. Abstract Figure. Fluoroscopic time analysis

CME ECG 68: Gender Specificities in Heart Rhythm Disorders

CME ECG 68: Gender Specificities in Heart Rhythm Disorders Abstract. Sex differences in heart rhythm disorders have been described, especially due to differences of hormone status in women and men. In general, women do have a higher baseline heart rate than men and shorter refractory periods of most structures in the conduction system, except the ventricles. This is particularly apparent in paroxysmal supraventricular tachycardias. The incidence of a dual AV nodal physiology is the same in both sexes. However, an AV-nodal reentry tachycardia is much more frequent in women than in men. The embryonal disposition for an accessory pathway, as well as the resultant AV reentry tachycardia is more common in men than in women. Focal atrial tachycardias do not reveal a clear dominance between the sexes. Knowledge about sex-related differences in heart rhythm disorders are relevant for its diagnostics. Therefore, important aspects will be discussed in this article.

Association of Fetal Atrial Flutter with Neonatal Atrioventricular Re-entry Tachycardia Involving Accessory Pathway: A Link to be Remembered.

To investigate prenatal and postnatal outcomes of atrial flutter and its association with the development of a second tachycardia, following restoration of sinus rhythm, in the fetus or newborn. This study is a retrospective review of all fetuses that presented with atrial flutter from January 2001 to December 2019 at the University Hospital of Wales, Cardiff, UK. The specific type of arrhythmia, its time of appearance and clinical characteristics, echocardiographic findings, medical management, and postnatal outcomes were evaluated. Sixteen fetuses were diagnosed with atrial flutter (AFL). Thirteen fetuses had persistent AFL and three fetuses had intermittent AFL. Seven patients had hydrops, of which one had Ebstein's anomaly and the other six had normal hearts. Three of the fetuses that presented with AFL were diagnosed at 20, 21, and 23 weeks' gestation and the remainder were diagnosed in the third trimester. Thirteen patients with AFL received antiarrhythmic drugs and three were delivered without any treatment. Five fetuses with AFL developed atrioventricular reciprocating tachycardia following DC cardioversion after birth, and four of them exhibited pre-excitation on the ECG. These five patients (31.3%) required postnatal antiarrhythmic treatment for up to 2years. Pre-excitation disappeared in two patients during follow-up and two asymptomatic patients with neonatal pre-excitation required accessory pathway ablation. Fetal atrial flutter has a strong association with atrioventricular reciprocating tachycardia and ventricular pre-excitation in the neonatal period. Therefore, electrocardiograms should be carefully reviewed in newborns following the initial resolution of atrial flutter.

Referral patterns and Outcome of Children with Perceived Arrhythmia to a Tertiary Cardiac Service

Background &amp; Objectives: Arrhythmias are common in pediatric population and is suspected in patients presenting with palpitations and/or syncope. These patients are commonly referred to Pediatric Cardiology for further evaluation either after identifying rhythm abnormality or based on clinical suspicion only. The objective of this study was to assess the yield of pediatric cardiology referrals for arrhythmia evaluation. Methods: This is a single-center retrospective observational descriptive study. A total of 486 patients referred to the pediatric cardiology department from the year 1998 to 2020 were included. Patients were grouped based on referral, Group 1 consisted of patients referred with documented arrhythmia and Group 2 had patients referred on clinical suspicion. Patient’s age at presentation, gender, reason for referral, type of arrhythmias, any associated structural heart disease, interventions, and outcomes were analysed. Results: Group 1 had 156 (32.1%) patients and group 2 had 330 (67.9%) patients. The most common diagnosis in group 1 was atrioventricular re-entry tachycardia and in group 2 was premature ventricular contractions. There was no variability for the type of arrhythmia between the two groups. Among patients in group 2, 315 (95.4%) had no evidence of electrophysiological abnormalities. Positivity rates for arrhythmia were only 3.2% for palpitations and 9% for syncope. 28 (5.8 %) patients required interventions; all from group 1. Conclusion: Clinically significant arrhythmias were mostly diagnosed at the point of first contact. Patients referred on clinical suspicion were mostly normal electro-physiologically. Inappropriate referrals increase the workload on pediatric cardiology services. There is an urgent need to regularise referrals. Keywords: Cardiac arrhythmia, Heart diseases, Referral and consultation, Syncope, Tachycardia

Abstract 15612: Force, Power, and Temperature Settings in Slow Pathway Modification Utilizing an Irrigated Force Sensing Ablation Catheter

Introduction: Atrioventricular node reentry tachycardia (AVNRT) ablation is typically performed with solid tip catheters set to temperature control (TC) mode. Radiofrequency (RF) output, tip temperature (T), and junctional rhythm response (JRR) during RF application have been well defined. JRR in an intermittent burst, sinus-junction-junction, or sinus-junction-sinus pattern is associated with successful modification of the AV nodal slow pathway (SP). Irrigated force-sensing catheters (IFSC) are often utilized for mapping and ablation of the SP. Despite this, parameters for IFSC used in TC mode resulting in JRR have not been well described. Hypothesis: Parameters predicting JRR and successful SP modification with IFSC include power (P), force (F), impedance drop (I), and target temperature (T). Methods: Consecutive patients that underwent electrophysiologic study and successful ablation of typical AVNRT with an IFSC were studied. Lesion parameters including P, T, F, time and I change were analyzed. Lesions producing JRR were considered efficacious. Independent T-Test and ANOVA were used to determine significance between the two groups (efficacious and non-efficacious lesions). Results: 296 lesions in 39 patients (age 52+/-14) were analyzed. All patients had successful SP modification without complication. Average F producing JRR was 8g, average T producing JRR was 41 o C, average I drop producing JRR was 9 Ohms, and average P producing JRR was 28W. Only RF lesion time was a significant predictor of JRR (p=0.009). (Table 1). Conclusions: Successful SP modification with IFSC was accomplished with catheter contact force as low as 2g. Lower average tip T, and lower average P settings compared to parameters typically used with solid tip catheters were observed. Parameters including P, F, T, and I change were not predictive of JRR. Additional studies controlling for catheter location while varying parameters are indicated.