Atrioventricular Reentry Tachycardia Research Articles

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

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 > 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 > 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]
 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.
 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 > 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 >1 SVT ablated during the procedure (0.04) and require intracardiac echocardiography (ICE) (p < 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 < 0.001). EAM was also associated with a longer procedure time (mean +8.8 minutes, p < 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 < 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.

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.