Atrioventricular Reentry Tachycardia Research Articles

Median dose area product and fluoroscopy time have stabilized on a low level during the last years: data from the swedish national catheter ablation registry

Abstract Background Despite the utilization of 3D-mapping systems, the use of fluoroscopy is still necessary in most procedures of catheter ablations of arrhythmias, but associated with serious health risks to both patients and operators. However, given the rapid improvement of the 3D-mapping systems, the usage of fluoroscopy has likely decreased during the past 15 years. Purpose The purpose of this study was to explore trends over time in usage of fluoroscopy in catheter ablation for all arrhythmias. Methods The Swedish Catheter Ablation Registry covers virtually all (>97%) catheter ablations performed in Sweden since 2005. Patients >18 years of age undergoing catheter ablation from January 1st 2006 to December 31st 2020 were included. Periprocedural data; median dose area product and fluoroscopy time were analyzed and compared. Periprocedural data were compared between 2006, 2015 and 2020 to find possible trends. Results A total of 61242 procedures were performed during the study period. The breakdown between the different arrhythmias was: 3% ventricular tachycardia (VT), 3% premature ventricular complex (PVC), 5% atrial tachycardia (AT), 7% atrioventricular junction ablation (AVJ), 10% atrioventricular reentry tachycardia (AVRT), 14% cavotricuspid isthmus ablation (CTI), 20% atrioventricular nodal reentry tachycardia (AVNRT) and 39% atrial fibrillation (AF). In 2006, the median fluoroscopy duration for AF, VT and PVC were recorded at 41, 32 and 37 minutes, respectively. Subsequently in 2015 the corresponding times were recorded at 14, 8 and 13 minutes. In 2020 respective procedures had a median fluoroscopy time of 11, 10 and 18 minutes (p< 0.001 for trend for all ablations). In 2006 median dose area product for AF, VT and PVC were 3998 cGycm2, 4300 cGycm2, and 5138 cGycm2, respectively. By 2015 the median dose area product had decreased to 1005 cGycm2, 432 cGycm2 and 1123 cGycm2 respectively. In 2020 the median dose area product had decreased further to 524 cGycm2, 380 cGycm2 and 848 cGycm2 (p<0.001 for trends for all ablations). See figure 1 for all procedures. Conclusion Fluoroscopy time and median dose area product have decreased significantly over a 15-year period and have stabilized on a low level over the last 5 years. Given the associated risks, efforts to further reduce radiation exposure are clearly warranted.Median dose area product

Collision mapping enables accurate localization of the slow pathway in atrioventricular nodal reentrant tachycardia

Abstract Introduction Atrioventricular Node Reentry Tachycardia (AVNRT) is commonly treated with catheter ablation, with high success and low complication rates. However a small risk of complete AV block still remains. Recent studies could show that using collision map is a feasible approach in mapping the slow pathway. The aim of the current study is to show a reduction of the total ablation points needed to modify/ablate the slow pathway using the collision mapping compared to conventional 3D mapping guided slow pathway modulation/ablation and therefore minimize the risk of a complete heart block. Methods Patients diagnosed with AVNRT (n = 24) underwent collision mapping for slow pathway identification, compared to a historical cohort (n=76) using conventional mapping. For collision mapping a dynamic visualization of atrial propagation during sinus rhythm was condcted. Two propagation fronts were observed to collide at the triangle of Koch, one propagation through the slow and one through the fast pathway. The designated collision zone was considered ideal for catheter ablation (Figure 1). The endpoint after ablation in both groups was non-inducibility of AVNRTs. Results After propensity score matching the collision mapping group needed significantly fewer ablation impulses (2 (IQR 1 - 5) vs. 6 (IQR 2,5 - 11,5) p = 0.002) and shorter ablation time (p < 0.001) compared to the conventional group (Table 1). No significant differences were observed in procedure time (p = 0.209), fluoroscopy time (p = 0.296), or dose area product (p = 0.391). Conclusion Collision Mapping in AVNRT ablation showed a notable reduction in ablation points, suggesting enhanced procedural efficiency and safety.Figure 1Table1

Evaluation of pediatric patients with palpitations via cardiac event recorder, Holter monitoring and transesophageal electrophysiologic study in detecting arrhythmia

Objective: Palpitations are a common reason for referral to pediatric cardiologists, the diagnostic workup involves ambulatory, non-invasive recording devices and invasive procedures. We aimed to evaluate arrhythmic symptoms of pediatric patients with a cardiac event recorder, Holter monitoring and transesophageal electrophysiologic study (TEEPS) results. Materials and Methods: Retrospective evaluation of pediatric patients who fitted an event recorder at tertiary University Hospital between January 2002 and August 2012. The data obtained from the same patients’ as cardiac event recorder, Holter monitoring and TEEPS results were studied for comparison. Results: During the study period, 40 patients who had all data of cardiac event recorder, Holter monitoring and TEEPS were included. The median age of the patients included in the study was 12 [interquartile range, 7-15] years. Using the Holter monitoring, supraventricular extrasystoles (SVEs) were detected in six (15%) patients and ventricular extrasystoles (VESs) in three (7.5%). According to the event recorder data of the 40 patients, there was sinus tachycardia in 20 (50%), supraventricular tachycardia (SVT) in three (7.5%), and SVEs in two (5%) patients. The event recorder data of the remaining 15 patients were assessed as normal. The analysis of the TEEPS results revealed atrioventricular nodal reentrant tachycardia in four (10%), atrioventricular reentry tachycardia in three (7.5%), and normal results in the remaining 33 (82.5%) patients. Conclusions: This study demonstrated that a cardiac event recorder may also be considered as an important diagnostic tool in the diagnosis and ruling out of SVT in pediatric patients for whom the cause of arrhythmia cannot be identified with the Holter monitor, in patients who do not accept the use of TEEPS method following the use of Holter monitor, and in patients in whom SVT cannot be stimulated by TEEPS yet complaints persist.

Benefits from catheter ablation in patients with pulmonary hypertension: Recent advances.

Supraventricular tachycardia (SVT) is a frequent complication of pulmonary hypertension (PH). The most prevalent SVTs are atrial fibrillation (AF) and typical atrial flutter (AFL), followed by focal and macroreentrant atrial tachycardia (AT) and nodal arrhythmia (AV nodal reentry tachycardia or AV reentry tachycardia). SVT is frequently associated with functional deterioration and right ventricular failure in PH patients. According to some data, reestablishing sinus rhythm is associated with clinical improvement. Catheter ablation of typical AFL, nodal tachyarrhythmias, or other less complex focal ATs have been shown to be feasible, acutely effective, and safe in patients with PH. However, the long-term clinical outcome is modified by the recurrence of index arrhythmia and the onset of a new SVT. Due to right atrial dilatation, technical issues can arise when ablation is carried out. The role of catheter ablation in patients with AF or more complex AT is even less effective. The results mirror the success rate in the general AF population with non-paroxysmal AF. However, the data is limited, and electrophysiological procedures are also more often complicated by specific adverse events in a severely frail population. Despite these limitations, catheter ablation is the treatment of choice in less complex SVT, but the indications for AF ablation must be more individualized.

Feasibility of catheter ablation with zero-fluoroscopy in congenital heart disease

Abstract Background Catheter ablation (CA) with zero and near-zero fluoroscopy has been shown to be safe and effective in patients (pts) without structural heart disease, but there are limited data regarding CA in congenital heart disease (CHD). Aim Our aim was to compare the safety and outcome of zero-fluoroscopy (ZF) and fluoroscopy (non-ZF) CA of CHD pts. Methods This is a single-center retrospective study of CHD pts who underwent CA at our center between 2006-2020. The ZF and non-ZF groups were compared for the complexity of anatomy, arrhythmia substrate, difficulties of vascular access, transseptal or transbaffle puncture, intracardiac pacemaker/ICD, procedural parameters, complications, and acute outcome. Near-ZF CAs (effective dose ≤1 mSv) were assigned to the ZF group. Results The ZF group included 22 pts (age: 22±13 years) and the non-ZF group 48 pts (age: 31±12 years). The distribution of CHD anatomical complexity (mild/moderate/severe) was 18.2%-68.2%-13.6% in the ZF group and 14.6%-68.7%-16.7% in the non-ZF group. Arrhythmia diagnoses were focal atrial tachycardia (ZF: 4.6%), atrial flutter (ZF: 45.4%, non-ZF: 75.0%), atrioventricular reentry tachycardia (AVRT) via manifest accessory pathway (AP) (ZF: 31.8%, non-ZF: 10.4%), AVRT via concealed AP (ZF: 4.6%, non-ZF: 8.3%), and atrioventricular nodal reentry tachycardia (ZF: 13.6%, non-ZF: 6.3%). Difficulties in vascular access occurred in 4.5% of the ZF group and 18.8% of the non-ZF group (p=0.10). The rate of transseptal/transbaffle puncture was significantly higher in the non-ZF group (22.9% vs. 4.6%, p=0.04). In the ZF group 13.6% and in the non-ZF group 20.8% of pts had pacemaker or ICD (p=0.22). Electroanatomical mapping was used in all CAs in both groups. There was no significant difference in procedure time, ablation time and the number of radiofrequency applications (ZF group: 169±53 min, 1205±906 sec, 28±15 vs. non-ZF group: 203±74 min, 1459±940 sec, 34±16, p>0.05). The acute success rate was 100% in both groups. No complications occurred in any group. Conclusion Zero fluoroscopic CA was feasible in 1/3 of the pts with CHD and as safe and effective as fluoroscopic ablation. No significant differences were found in the non-fluroscopy related procedural data between the two groups.

Pre-Excited Atrial Fibrillation in Wolff-Parkinson-White (WPW) Syndrome: A Case Report and a Review of the Literature.

Wolff-Parkinson-White (WPW) syndrome is defined by specific electrocardiogram (ECG) changes resulting in ventricular pre-excitation (the so-called WPW pattern), related to the presence of an accessory pathway (AP), combined with recurrent tachyarrhythmias. WPW syndrome is characterized by different supraventricular tachyarrhythmias (SVT), including atrioventricular re-entry tachycardia (AVRT) and atrial fibrillation (AF) with rapid ventricular response, with AVRT being the most common arrhythmia associated with WPW, and AF occurring in up to 50% of patients with WPW. Several mechanisms might be responsible for AF development in the WPW syndrome, and a proper electrocardiographic interpretation is of pivotal importance since misdiagnosing pre-excited AF could lead to the administration of incorrect treatment, potentially inducing ventricular fibrillation (VF). Great awareness of pre-excited AF's common ECG characteristics as well as associated causes and its treatment is needed to increase diagnostic performance and improve patients' outcomes. In the present review, starting from a paradigmatic case, we discuss the characteristics of pre-excited AF in the emergency department and its management, focusing on the most common ECG abnormalities, pharmacological and invasive treatment of this rhythm disorder.

Probable atrioventricular reentry tachycardia (Node to Node) in a patient with right atrial isomerism in the immediate postoperative period of palliative surgery

Probable atrioventricular reentry tachycardia (Node to Node) in a patient with right atrial isomerism in the immediate postoperative period of palliative surgery

Classification of underlying paroxysmal supraventricular tachycardia types using deep learning of sinus rhythm electrocardiograms.

Obtaining tachycardia electrocardiograms (ECGs) in patients with paroxysmal supraventricular tachycardia (PSVT) is often challenging. Sinus rhythm ECGs are of limited predictive value for PSVT types in patients without preexcitation. This study aimed to explore the classification of atrioventricular nodal reentry tachycardia (AVNRT) and concealed atrioventricular reentry tachycardia (AVRT) using sinus rhythm ECGs through deep learning. This retrospective study included patients diagnosed with either AVNRT or concealed AVRT, validated through electrophysiological studies. A modified ResNet-34 deep learning model, pre-trained on a public ECG database, was employed to classify sinus rhythm ECGs with underlying AVNRT or concealed AVRT. Various configurations were compared using ten-fold cross-validation on the training set, and the best-performing configuration was tested on the hold-out test set. The study analyzed 833 patients with AVNRT and 346 with concealed AVRT. Among ECG features, the corrected QT intervals exhibited the highest area under the receiver operating characteristic curve (AUROC) of 0.602. The performance of the deep learning model significantly improved after pre-training, showing an AUROC of 0.726 compared to 0.668 without pre-training (p < 0.001). No significant difference was found in AUROC between 12-lead and precordial 6-lead ECGs (p = 0.265). On the test set, deep learning achieved modest performance in differentiating the two types of arrhythmias, with an AUROC of 0.708, an AUPRC of 0.875, an F1-score of 0.750, a sensitivity of 0.670, and a specificity of 0.649. The deep-learning classification of AVNRT and concealed AVRT using sinus rhythm ECGs is feasible, indicating potential for aiding in the non-invasive diagnosis of these arrhythmias.

Digital health in the EP lab: Initial experience using remote access and technical support for complex ablation procedures

Abstract Aims/Objectives Three-D electroanatomical mapping (EAM) systems are a prerequisite for treatment of complex arrhythmias. Until date, the EAM system is operated by qualified staff or a field technical engineer (FTE) from the control room. Novel technology allows for remote access (RA) of the EAM from anywhere in the world. RA increases the flexibility of the EP lab, reduces travel time for the FTE and overcomes hospital access limitations e. g. during the COVID-19 pandemic. We report on the safety and feasibility of remote operation of the EAM for complex ablation procedures. Methods RA mapping was achieved by combining the EAM software with an integrated audiovisual solution for remote support. Communication between the operator and the remote support was achieved using internet-based headphones in the RA group. The 3D EAM system was controlled exclusively from home office. In the conventional group (CG), EAM was exclusively controlled from the control room in the EP lab. Ablation procedures were performed as per institutional standard. Results We investigated 50 RA assisted consecutive electrophysiological procedures from 09/2022 to 02/2023 in our University Heart Center. We compared a group of patients undergoing ablation procedures with RA assistance (28/50 (56%) patients were male, median age: 66.5 yrs [IQR 56, 76], BMI: 25.2 kg/m2 [IQR 22, 30]) with a control group (31/50 (62%) male, median age: 66.5 yrs [IQR 54, 78], BMI 28.2 kg/m2 [IQR 24, 30], p &amp;gt; 0.05 for all). Ablation procedures were matched in both groups: 20 pulmonary vein isolations (3 paroxysmal, 17 persistent atrial fibrillation ), 4 cavotricuspidal isthmus ablations, 13 ablations of atrial tachycardia, 1 premature ventricular complex ablation, 3 of ventricular tachycardia, 2 AV reentry tachycardia and 7 AV-node reentry tachycardia cases. In the RA group, the 3D EAM system was controlled exclusively from home office in all patients. In one patient, the internet based headphone connection was instable. Therefore, the communication was established via a conventional smartphone. No other technical issue was noted. No switch to in house support was required. There were no major complications observed. Procedural data (total procedure time median 100 min [IQR 76, 120] vs. control group 86 min [IQR 60, 110], total fluoroscopy time (median 9.1 min [IQR 6, 13] vs. control group 8.7 min [IQR 5, 12], p &amp;gt; 0.05) were comparable to previous procedures without RA. Due to RA travel time could be reduced by 139 hr in total in comparison to the control group. Conclusions RA for EAM of any arrhythmia is feasible and safe in this single center study. Procedural data were comparable to previous procedures. In the future, this new solution might have a great impact on facilitating EP procedures.Table procedural data

The value of 12-lead electrocardiography in predictive mechanism of regular narrow qrs complex paroxysmal supraventricular tachycardias

Background: Paroxysmal supraventricular tachycardia (NNKPTT) is the most common clinical occurrence, affecting hemodynamics and causing symptoms of palpitations and dyspnea in patients. Of the mechanisms that cause paroxysmal supraventricular tachycardia, atrioventricular nodal re-entry tachycardia (AVNRT), atrioventricular re-entrant tachycardia (AVRT), and atrial tachycardia (AT) are the most common and difficult to distinguish each other. The electrocardiogram can be used to confirm and diagnose the mechanism of paroxysmal supraventricular tachycardia. [1]&#x0D; Objectives: to evaluate the predictive ability of the 12-lead electrocardiogram to predict the mechanism of paroxysmal supraventricular tachycardia with regular narrow QRS complex. Methods: cross-sectional descriptive method for 92 patients.&#x0D; Results: prevalence of paroxysmal supraventricular tachycardia mechanisms in the study was: atrioventricular nodal reentry tachycardia accounted for 69.6%; atrioventricular reentry tachycardia accounted for 27.2%; atrial tachycardia accounted for 3.4%. In univariate regression analysis, the ECG criteria with 95% CI of OR not containing a value of 1 were: clear P' wave, pseudo r' wave in V1, ST-T segment change, electrical alternation , pseudo r wave in aVR. In the multivariable regression model, the independent predictors AVNRT with AVRT are clear P' waves and ST–T segment changes.

Case series of catheter-based arrhythmia ablation in 13 pregnant women.

Catheter ablation is a rarely used procedure to treat arrhythmias during pregnancy. In the case of maternal arrhythmia during pregnancy, zero-fluoroscopic catheter ablation is preferable to medical treatment. Between April 2014 and September 2021, we examined the demographic data, procedural parameters, and fetal and maternal outcomes in pregnant women undergoing ablation at the Gottsegen National Cardiovascular Center and University of Pécs Medical School, Heart Institute. Fourteenprocedures (14 electrophysiological studies [EPS], 13 ablations) performed on 13 pregnant women (age 30.3 ± 5.2 years, primipara n = 6) were studied. During EPS, 12 patients had inducible arrhythmias. Atrial tachycardia was confirmed in three, atrioventricular re-entry tachycardia via manifest accessory pathway (AP) in three, and via concealed AP in one case. Atrioventricular nodal re-entry tachycardia was confirmed in three and sustained monomorphic ventricular tachycardia in two cases. Eleven radiofrequency ablation (84.6%) and two cryoablation (15.4%) were performed. The electroanatomical mapping system was used in all cases. Transseptal puncture was performed in two cases (15.4%) due to left lateral APs. The mean procedure time was 76.0±33.0 minutes. All procedures were performed without fluoroscopy. No complications occurred. During the follow-up, arrhythmia-free survival was achieved in all cases, but in two patients, we used antiarrhythmic drugs (AADs) to achieve it. APGAR score was within the normal range in all cases [median (interquartile range),9.0/10.0 (9.0-10.0/9.3-10.0)]. Zero-fluoroscopic catheter ablation was an effective and safe treatment option for our 13 pregnant patients. Catheter ablation may have less side effects on fetal development than the use of AADs during pregnancy.

Occam's Razor: Two Arrhythmias in a Single Heart?

Occam's Razor: Two Arrhythmias in a Single Heart?

Impact of 3-dimensional electroanatomic mapping systems on fluoroscopy reduction in catheter ablation of supraventricular tachycardia - then and now

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation is an effective first-line treatment for symptomatic and recurrent supraventricular tachycardia (SVT). The advent of 3D electroanatomic mapping (EAM) has led to a reduction in fluoroscopy use and consequently lower radiation exposure for patients and staff during SVT ablation. Purpose The aims of this study are to demonstrate if the use of EAM during SVT ablation reduces fluoroscopy time (FT), and determine if further reductions in FT are observed longitudinally. We hypothesise that over time, with continued use and wider adoption of EAM, greater operator experience, and technological advancements in EAM, there will be further reductions in radiation exposure as estimated by FT. Methods All cases of atrioventricular nodal re-entry tachycardia (AVNRT), atrioventricular re-entry tachycardia (AVRT), and/or atrial tachycardia (AT) ablation between May 2011 to May 2022 at a tertiary centre were prospectively recruited. FT between the groups with and without EAM were compared. Within the EAM subset, the trend of FT across the years was also analysed. Results Over this 11-year period, there were 1758 cases of SVT ablation (565 without EAM; 1193 with EAM). Between the two groups, there were no significant differences (p &amp;gt; 0.05) in age, sex, history of structural heart disease and/or ischaemic heart disease, stereotaxis use, and diagnosis (AVNRT, AVRT, AT). Cases using EAM were more likely to have &amp;gt;1 SVT ablated during the procedure (0.04) and require intracardiac echocardiography (ICE) (p &amp;lt; 0.001). The use of EAM was associated with mean reductions in FT and dose area product (DAP) by 19.6 minutes and 18 581 mGy*cm2 respectively (both p &amp;lt; 0.001). EAM was also associated with a longer procedure time (mean +8.8 minutes, p &amp;lt; 0.001). There was no difference in radiofrequency application time between the two groups (p = 0.143). After controlling for potential confounding factors including age, sex, use of stereotaxis, use of ICE, type and number of SVT, history of prior ablation, and structural heart disease and/or ischaemic heart disease, we found over time (2011-2022), further reduction in FT was observed, with a mean reduction of 0.9 minutes year on year (p &amp;lt; 0.001). EAM was gradually adopted through the years with the number of cases per year plateauing after 2017. Between 2011-2017, there was a significant reduction in FT (mean of -1.1 minute year on year, p = 0.020), which was not observed from 2017 onwards (p = 0.088). The greatest reduction in FT was observed after the first year of adoption, with a mean reduction of 6.9 minutes between 2012-2013. Conclusion This demonstrates that use of EAM in SVT ablation reduces FT and fluoroscopy DAP. There was no incremental benefit observed after 6 years of EAM adoption likely related to operator experience. While there is increased interest in zero fluoroscopy SVT ablation, complementary use of fluoroscopy may still be necessary in select complex cases.

Fluoroless vs. conventional catheter ablation of supraventricular tachycardia - retrospective single-centre analysis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Radiofrequency (RF) catheter ablation of supraventricular tachycardia (SVT) is a gold-standard therapy that offers excellent results. Conventional approach using fluoroscopy has been challenged by the increasing use of electroanatomical mapping (EAM) systems and intracardiac echosonography (ICE) which eliminate the radiation hazard for the patient and medical personnel. They offer good results without compromising safety or efficacy but also require further research. (1, 2) Their widespread use is limited by their cost but is steadily increasing. Purpose To compare the acute outcomes of fluoroless SVT ablation to those of conventional procedures since widespread introduction of this novel technology in our institution. Methods Data about patients with AV-node reentry tachycardia (AVNRT), atrio-ventricular reentry tachycardia (AVRT), atrial tachycardia and atrial flutter (AFL) who were treated with ablation were retrospectively collected using hospital medical records. 80 consecutive patients who underwent fluoroless SVT ablation formed the fluoroless (FL) group. Last 80 patients who previously underwent conventional SVT ablation using fluoroscopy served as a control group. Two different EAM systems were used in the FL group (Abbot Ensite and Biosense Webster CARTO). All procedures were performed by 3 different experienced operators. Results The fluoroless and control group were similar regarding age, sex and comorbidities. Approximately half of all patients in both groups suffered from AVNRT. AVRT was more common in the FL group and AFL in the control group (23.4% vs. 10.0% and 20.8% vs. 37.5% respectively). This was responsible for the difference in the use of ICE and need for transseptal puncture between the groups. Detailed group characteristics are shown in Table 1. Procedure duration was similar in both groups (58.0 ± 25.5 min vs. 63.9 ± 25.3 min in FL and control group respectively, p=0.12). Ablation time, calculated as duration of RF energy delivery, tended to be shorter in the FL group (396 ± 44 vs. 575 ± 636 s) but failed to reach the level of statistical significance (p=0.06). Acute success, defined as non-inducibility of arrhythmia or, in case of AFL, cavotricuspid isthmus conduction block, was achieved in 98.8% and 97.5% of cases in FL and control group respectively. There were no cross-overs from FL group to fluoroscopy. In the control group, mean fluoroscopy duration was 9.7 ± 7.5 min and radiation dose 14.6 ± 21.6 mGy. One steam pop occurred in the FL group but the patient suffered no acute or chronic consequences. There were no other complications. Conclusion Technologies for fluoroless SVT ablation have been widely implemented in our institution with very good acute results and safety profile that is non-inferior to conventional approach. By eliminating risks inherent to fluoroscopy they could be beneficial for patients and physicians likewise. Follow-up data are needed to confirm these results.

PO-05-229 DEEP LEARNING CLASSIFICATION OF PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA TYPES USING SINUS RHYTHM ELECTROCARDIOGRAMS

Only sinus rhythm electrocardiograms (ECGs) are often available in patients with paroxysmal supraventricular tachycardia (PSVT). However, sinus rhythm ECGs have a limited value in classifying PSVT types. We aimed to investigate the deep learning approach of classifying Atrioventricular Nodal Reentry Tachycardia (AVNRT) from concealed Atrioventricular Reentry Tachycardia (AVRT) using sinus rhythm ECGs. We collected the patients with AVNRT or conceald AVRT, and their 12-lead ECGs with sinus rhythm. The diagnosis of each patient was validated with an electrophysiology study. ResNet-34 was used for the deep learning model, and it was trained to classify sinus rhythm ECGs with underlying AVNRT and conceald AVRT. Due to the limited training dataset, transfer learning was performed by pre-training of an open-source ECG database (PhysioNet/CinC Challenge 2021). Ten-fold cross-validation was used to validate deep learning performance. Integrated gradient analysis was used to visualize which ECG segment is important for the model to classify the two arrhythmias. A total of 696 patients with AVNRT and 305 patients with conceald AVRT were analyzed. Compared to the AVNRT group, the conceald AVRT group was significantly younger and had a higher male proportion; age 48 vs. 51 years (p<0.001); male 63.3 vs. 34.3% (p<0.001). After the pre-training, the deep learning performance was significantly improved; AUROC 0.73 (95% CI 0.69-0.76) vs. 0.67 (0.62-0.72) for with and without pre-training; p<0.001 (Figure A). Deep learning showed modest performance for classifying the two arrhythmias; AUPRC, F1-score, sensitivity, and specificity were 0.84 (0.81-0.87), 0.75 (0.70-0.80), 0.68 (0.61-0.75), and 0.71 (0.65-0.77), respectively. Deep learning focused on PR intervals and T waves for identifying AVNRT, and P-waves for concealed AVRT (Figure B). Deep learning classification of AVNRT and conceald AVRT was feasible with sinus rhythm ECGs.

Long-term follow-up in preschool children after radiofrequency catheter ablation of arrhythmias.

Radiofrequency ablation (RFA) is the standard method of treatment for tachyarrhythmias in school children, and it leads to complete recovery in children without structural heart disease. However, RFA in young children is limited by the risk of complications and unstudied remote effects of radiofrequency lesions. To present the experience of RFA of arrhythmias and the results of follow-up of younger children. RFA procedures (n=255) were performed in 209 children with arrhythmias from 0 to 7 years old. The arrhythmias were presented with atrioventricular reentry tachycardia withWolff-Parkinson-White(WPW) syndrome (56%), atrial ectopic tachycardia (21.5%), atrioventricular nodal reentry tachycardia (4.8%), and ventricular arrhythmia (17.2%). The overall effectiveness of RFA, considering the repeated procedures performed due to the primary ineffectiveness and recurrencies, was 94.7%. There was no mortality associated with RFA in patients, including young patients. All cases of "major" complications are associated with RFA of the left-sided accessory pathway and tachycardia foci and are represented by the mitral valve damage in three patients (1.4%). Tachycardia and preexcitation recurred in 44 (21%) patients. There was a correlation between recurrences and parameters of RFA (odds ratio 0.894; 95% confidence interval: 0.804-0.994; p=.039). Reducing the maximum power of effective applications in our study increased the risk of recurrence. The use of the minimum effective parameters of RFA in children reduces the risk of complications, but increases arrhythmia recurrence rate.

Not Just a One-Way: Mahaim Accessory Pathway Concomitantly Supporting Orthodromic Atrioventricular Re-Entrant Tachycardia

We report the case of a 41-year-old female with documented narrow QRS tachycardia. During electrophysiological study, both orthodromic and antidromic atrioventricular reentry tachycardia (AVRT) were demonstrated as well as short episodes of pre-excited atrial fibrillation. Programmed atrial stimulation resulted in decremental anterograde conduction on the AP, thus confirming an unexpected Mahaim accessory pathway (AP) diagnosis. Limited 3D activation maps of the right atrium during orthoAVRT, respectively, and the right ventricle (RV) during antiAVRT were constructed and helped accurately describe the atrial and ventricular insertion points, which were superposed on the tricuspid ring, confirming the existence of a single short atrio-ventricular right free wall AP. Short atrioventricular APs with anterograde Mahaim-type conduction concomitantly sustaining orthodromic AVRT are extremely rare. Electroanatomical 3D mapping may help both to clarify the diagnosis and increase the success rate by accurately describing the insertion points of complex accessory pathways.

Electrophysiological guided accessory-pathway ablation strategy in children with asymptomatic WPW: it may not be enough to prevent sudden cardiac death.

Sudden cardiac death (SCD) may rarely occur among asymptomatic patients with Wolff-Parkinson-White (WPW) pattern. Risk stratification is based on electrophysiological study (EPS). We aimed to evaluate long-term efficacy of such a strategy in preventing SCD. Retrospective analysis of asymptomatic children with WPW who underwent EPS using isoproterenol. Patients considered at risk had inducible sustained atrial fibrillation or atrioventricular reentry tachycardia (AVRT) associated with the following: (1) accessory pathway (AP) effective refractory period or (2) 1:1 shortest cycle length along the AP or (3) shortest pre-excited R-R interval during AF ≤ 250ms. Fifty-one consecutive cases (7-18years, 12 ± 3) were identified, 40 (78%) with right and 11 (22%) with left AP. Twenty-eight (55%) were classified as high risk (HI) and 23 (45%) as low risk (LO), with no significant differences in demographic characteristics and AP locations. Ablation was performed in 20/28 HI and 11/23 LO patients (p 0.08), with no significant differences in acute success (20/20 versus 10/11, p 0.17) or recurrence (1/20 versus 2/10, p 0.15). Follow-up (46 ± 27months): ablated patients remained asymptomatic; among the 23 non-ablated, 18 (78%) remained asymptomatic, 5 (22%) were successfully ablated, and 5 (22%) presented events (4 AVRT, 1 SCD). Arrhythmic events did not differ significantly between non-ablated HR and LR (2/8 versus 3/15, p 0.29) and the SCD was in the LO group. More than 50% asymptomatic WPW children present high-risk AP properties. EPS-based risk stratification using isoproterenol was not able to identify increased risk of future events or SCD.

Variability of the VA interval at tachycardia induction: a simple method to differentiate orthodromic reciprocating tachycardia from atypical atrioventricular nodal reentrant tachycardia.

The differential diagnosis between orthodromic atrioventricular reentry tachycardia (AVRT) and atypical AV nodal reentrant tachycardia (aAVNRT) is sometimes challenging. We hypothesize that aAVNRTs have more variability in the retrograde conduction time at tachycardia onset than AVRTs. We aimed to assess the variability in retrograde conduction time at tachycardia onset in AVRT and aAVNRT and to propose a new diagnostic tool to differentiate these two arrhythmia mechanisms. We measured the VA interval of the first beats after tachycardia induction until it stabilized. The difference between the maximum and minimum VA intervals (∆VA) and the number of beats needed for the VA interval to stabilize was analyzed. Atrial tachycardias were excluded. A total of 107 patients with aAVNRT (n = 37) or AVRT (n = 64) were included. Six additional patients with decremental accessory pathway-mediated tachycardia (DAPT) were analyzed separately. All aAVNRTs had VA interval variability. The median ∆VA was 0 (0 - 5) ms in AVRTs vs 40 (21 - 55) ms in aAVNRTs (p < 0.001). The VA interval stabilized significantly earlier in AVRTs (median 1.5 [1 - 3] beats) than in aAVNRTs (5 [4 - 7] beats; p < 0.001). A ∆VA < 10ms accurately differentiated AVRT from aAVNRT with 100% of sensitivity, specificity, and positive and negative predictive values. The stabilization of the VA interval at < 3 beats of the tachycardia onset identified AVRT with sensitivity, specificity, and positive and negative predictive values of 64.1%, 94.6%, 95.3%, and 60.3%, respectively. A ∆VA < 20ms yielded good diagnostic accuracy for DAPT. A ∆VA < 10ms is a simple and useful criterion that accurately distinguished AVRT from atypical AVNRT. Central panel: Scatter plot showing individual values of ∆VA in atypical AVNRT and AVRT. Left panel: induction of atypical AVNRT. The VA interval stabilizes at the 5th beat and the ∆VA is 62ms (maximum VA interval: 172ms - minimum VA interval: 110ms). Right panel: induction of AVRT. The tachycardia has a fixed VA interval from the first beat. ∆VA is 0ms.

Endocardial ablation at the mitral valve vestibule and its surroundings for the treatment of arrhythmias linked to the greater cardiac vasculature.

The role of the epicardial vasculature in supraventricular and ventricular arrhythmias was described in clinical studies as well as its treatment by intravascular point ablation or alcohol injection. We report on a case series of patients with different arrhythmias linked to an epicardial site of origin with evidence supporting transmural extensions that were targeted for ablation with successful outcomes. The records of patients who has catheter ablation for Supraventricular or Ventricular arrhythmias between 2015 and 2020 was searched for patients with (1) arrhythmias linked to the epicardial vasculature and (2) findings to support an endocardial connection to the epicardial vasculature by activation mapping, pace mapping, or differential pacing, and (3) were successfully ablated via an endocardial approach only. From the data searched, we identified five patients with the following arrhythmias left ventricular summit ectopy, peri-mitral atrial flutter, preexcitation with inducible atrioventricular reentry tachycardia (AVRT), and a concealed left side accessory pathway with inducible AVRT that were linked to the following vessels: Great Cardiac vein, persistent left superior vena cava, left coronary cusp, and left ventricular outflow tract. Endocardial connections were supported by a combination of electro anatomical activation mapping, pace-mapping, and differential pacing. Endocardial ablations performed in all patients were successful without complications. This report highlights a subset of patients with arrhythmias linked to the greater cardiac vascular system that can be safely and effectively ablated endocardially, given the limitations and possible complications of epicardial ablation within or in the proximity of the epicardial vasculature.