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

Background: 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. Methods: 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. Results: 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. Conclusion: 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.

Double Ventricular Response with Aberrant Conduction Leading to Ventricular Dysfunction.

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

Ablação de Taquicardia Reentrante Nodal Atrioventricular com Crioablação Focal, Comparada com Ablação por Radiofrequência: Experiência em Centro Único / Ablation of Atrioventricular Nodal Reentrant Tachycardia with Focal Cryoablation, Compared with Radiofrequency Ablation: Single-Center Experience

Resumo Fundamento A ablação da taquicardia por reentrada nodal atrioventricular (TRNAV) com crioablação é uma alternativa à ablação por radiofrequência (RF) em pacientes devido ao baixo risco de bloqueio atrioventricular total. Um aumento nas recorrências precoces e tardias após a crioablação é relatado como uma desvantagem importante. Objetivos Neste estudo, objetivamos comparar o sucesso do procedimento agudo e as taxas de recorrência em longo prazo de pacientes com TRNAV submetidos a métodos. Métodos Foram incluídos no estudo 73 pacientes com TRNAV: 32 com crioablação e 41 com ablação por RF. Não houve diferença estatisticamente significativa entre o sucesso agudo do procedimento nos métodos. O procedimento de ablação foi realizado por operador com experiência em arritmologia. A escolha entre RF ou crioablação foi feita no laboratório de eletrofisiologia com base no material já disponível durante o procedimento. Após o procedimento, os pacientes foram avaliados a cada 3 meses durante 2 anos em controle policlínico. O nível de significância adotado na análise estatística foi de 5%. Resultados Os dois grupos de pacientes foram homogêneos. O tempo de fluoroscopia (p<0,001) foi menor, mas os tempos his-átrio (p=0,004) e his-ventricular (p=0,015) foram maiores no grupo crioablação. Não houve diferença significativa em termos de sucesso agudo do procedimento, salto pós-procedimento sem eco único e presença de eco e salto. Conclusões A crioablação requer menos tempo de fluoroscopia e é uma alternativa segura e não inferior à ablação por RF em pacientes com TRNAV. O risco de bloqueio AV é um problema significativo com o uso de energia de RF, tornando-o menos adequado para uso em pacientes jovens e fisicamente ativos.

Abstract Background The ablation of atrioventricular nodal reentrant tachycardia (AVNRT) with cryoablation is an alternative to radiofrequency (RF) ablation in patients due to the low risk of total atrioventricular block. An increase in early-late recurrences after cryoablation is reported as an important disadvantage. Objectives In this study, we aimed to compare the acute procedural success and the long-term recurrence rates of patients, with AVNRT who underwent methods. Methods 73 patients with AVNRT were included in the study: 32 with cryoablation and 41 with RF ablation. There was no statistically significant difference between acute procedural success in methods. The ablation procedure was performed by an operator experienced in arrhythmology. The choice of RF or cryoablation was made in the electrophysiology laboratory based on the material already available during the procedure. After the procedure, the patients were evaluated every 3 months for 2 years in polyclinic control. The significance level adopted in the statistical analysis was 5%. Results The 2 groups of patients were homogeneous. The fluoroscopy time (p<0.001) was shorter, but atrium-his (p=0.004) and his-ventricular (p=0.015) times were longer in the cryoablation group. There was no significant difference, in terms of acute procedural success, post-procedure jump without a single echo, and presence of echo and jump. Conclusions Cryoablation requires less fluoroscopy time and is a safe non-inferior alternative to RF ablation in patients with AVNRT. The risk of AV block is a significant problem with the use of RF energy, making it less suitable for use in young and physically active patients.

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

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

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

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

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

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

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

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

[Supraventricular tachycardia]. / Supraventrikuläre Tachykardien.

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

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

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

Koch's triangle voltage mapping for cryoablation of slow pathway in children: preliminary data of a novel high-density technique.

PURPOSE: Different authors have described three-dimensional (3D) voltage mapping of the Koch's triangle (KT) in order to find low-voltage bridges (LVB) as targets for a successful transcatheter ablation (TCA) of the slow pathway (SP) in children. Recently, the Advisor High Density (HD) Grid™ mapping catheter was introduced as new multipolar catheter for HD mapping. The aim of the study was to describe our preliminary experience with the use of HD Grid™ catheter in LVB and electrophysiologically guided cryoablation of SP in children. METHODS: Twenty-one children (mean age 13±3 years) with atrioventricular nodal re-entrant tachycardia (AVNRT) underwent cryoablation of SP guided by voltage HD mapping of the KT using HD Grid™ catheter. In order to better highlight the differences with conventional mapping, point collection was performed in each patient with this new multipolar catheter and with a quadripolar catheter. RESULTS: The conventional mapping collected 871±262 points and used 211±80 points in 887±275 s, whereas HD mapping collected 7468±2947 points, using 604±165 points in 513±181 s (p<0.001). Moreover, the LVB area mapped with HD Grid™ was about one-half smaller and clearly delineated. Cryoablation acute success rate was 100%. Overall median fluoroscopy exposure was 0.08 (0.01-5.42) µGy/m2, with a median fluoroscopy time of 0.1 (0.0-0.6) min. During the follow-up (4.8 ± 3.7 months), there were no recurrences. No complications occurred. CONCLUSIONS: Our preliminary experience shows that HD mapping is faster and offers higher spatial resolution and definition. Procedural time can be reduced maintaining the TCA safe, with reduced fluoroscopy use and success.

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

BACKGROUND: Catheter 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. OBJECTIVE: This 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). METHODS: This 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. RESULTS: In 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). CONCLUSION: In 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.

Cryoablation of atypical atrioventricular nodal reentry tachycardia.

AIM: Data on ablation for atypical recurrent atrioventricular nodal reentry tachycardia (AVNRT) and long-term follow-up are generally sparse. Furthermore, the rate of recurrence and safety of cryoablation for atypical AVNRT has not been established. We compared patients cryoablated for atypical AVNRT and typical AVNRT during long-term follow-up. METHODS: All patients (n = 2612) who underwent catheter ablation for AVNRT at the Karolinska University Hospital between January 2009 and August 2019 were analyzed. A total of 91 patients undergoing first-time cryoablation for atypical AVNRT were included. A control group with first-time cryoablation for typical AVNRT was matched in a 1:1 ratio. Patients were followed-up for recurrences for a median of 5.0 years (interquartile range: 3.1-7.5 years). RESULTS: After 5 years, AVNRT recurrence occurred in 10 patients (11.0%) in the atypical AVNRT group and in 8 patients (8.8%) in the typical AVNRT group (hazard ratio: 1.31 [95% confidence interval: 0.52-3.32]; p = 0.568). The duration of the index procedure was significantly longer for atypical compared to typical AVNRT ablation (132.1 ± 49.2 min vs. 110.1 ± 38.8 min; p = 0.001). Transient AV blocks occurred in a similar fashion in the atypical compared to typical group (11 [12.1%] vs. 4 [4.9%]; p = 0.103). However, no ablation induced persistent AV block developed in either group. CONCLUSION: Cryoablation for atypical AVNRT showed similar rate of recurrences and safety compared to typical AVNRT during long-term follow-up.

Wenckebach cycle length: A novel predictor for AV block in AVNRT patients treated with ablation.

BACKGROUND: Radiofrequency catheter ablation remains the most effective management option for atrioventricular nodal reentry tachycardia (AVNRT). The risk of atrioventricular (AV) block requiring permanent pacemaker is substantial, but, currently, a reliable method to predict this complication is lacking. METHODS: The electrophysiologic studies (EPS) and baseline characteristics of patients who underwent catheter ablation for the treatment of AVNRT were retrospectively analyzed to investigate predisposing factors for AV block after treatment. Patients were followed for AV block at one month and one year after hospital discharge. RESULTS: Among 784 patients treated with catheter ablation for AVNRT between 1999 to 2019, 15 developed AV block. Patients with AV block were older (p = .001). Among the recorded EPS parameters, patients with AV block had significantly higher Atrial His interval (120 vs. 110 ms, p = .049), Wenckebach cycle length (WCL) (400 vs. 353 ms, p < .001) and tachycardia CL (400 vs. 387 ms, P = .01) during the ablation compared to their peers without AV block. Additionally, only WCL (OR = 1.1, 95% CI 1.02-1.19, p = .017) remained significant after adjustment for age, gender, ERP, AH interval, and HR. This association was confirmed by comparing patients with (n = 15) and without (n = 15) AV block using propensity score-matching. A WCL≥400ms was associated with a 4-fold higher incidence of AV block (4.79% vs. 1.25%). CONCLUSION: Increased pre-procedural WCL was associated with a high risk for AV block after catheter ablation treatment for AVNRT. These findings suggest that this readily available EPS-derived parameter may be a novel marker of risk for severe complications in these patients.

Speckle-tracking echocardiography can predict atrial fibrillation in patients with supraventricular tachycardia.

PURPOSE: Atrioventricular nodal reentry tachycardia (AVNRT) is the most common supraventriculer arrhythmia in daily clinical practice. Comorbidity of AVNRT and atrial fibrillation (AF) has been well documented in some patients and AF development has been observed more frequently in AVNRT patients during their long-term follow-up. This study was conducted in order to investigate the left atrial two-dimensional-speckle-tracking echocardiographic (STE) parametres as the predictors of the occurence of AF in long-term follow-up in patients with spontaneously developed AF during AVNRT ablation. METHODS: Two hundred and thirty two consecutive AVNRT patients who developed spontaneous AF during ablation procedure were included in the study. The patients were followed up for a mean follow-up period of 6.2 ± 2.1 years. All patients were evaluated using the 2D-STE method. AF was developed in 34 patients during the follow-up period. Cox regression analysis was performed in order to identify the independent predictors of AF occurence. RESULTS: Left atrial LA-res, LA-pump, LA-SRs, LA-SRe, and LA-SRa values were found to be significantly decreased in the group of patients that developed AF during the follow-up period (p < .001 for all aforementioned values). Multivariate cox regression analysis revealed that LA-res (hazard ratio [HR], 0.367; 95% confidence interval [CI], 0.161-0.0.683, p < .001) and SRe (HR, 0.472; 95% CI, 0.346-0.825, p = .006) were independent risk factors associated with the occurrence of AF. CONCLUSION: In conclusion, it was demonstrated for the first time with this study that 2D-STE can effectively predict the development of AF in long-term follow-up in patients with spontaneously developed AF during AVNRT ablation.

Automated rhythm-based control of radiofrequency ablation close to the atrioventricular node: Preclinical, animal, and first-in-human testing.

BACKGROUND: The risk of heart block during radiofrequency ablation of atrioventricular (AV) nodal reentrant tachycardia and septal accessory pathways is minimized by rapidly ceasing ablation in response to markers of risk, such as atrioventricular dissociation, fast junctional rhythm, PR interval prolongation, or 2 consecutive atrial or ventricular depolarizations. Currently this is done manually. OBJECTIVES: The objectives of this study were to build and test a control system able to monitor cardiac rhythm and automatically terminate ablation energy when required. METHODS: The device was built from off-shelf componentry. Preclinical testing involved real-time input of electrogram/electrocardiogram data from 209 ablation procedures (20 patients) over slow (n = 19) and fast (n = 1) AV nodal pathways. The device response speed was compared with the human response speed. The device's ability to prevent heart block was tested in 5 sheep. First-in-human testing was then performed in 12 patients undergoing AV nodal reentrant tachycardia ablation. RESULTS: Risk conditions necessitating shutoff of ablation (200 total; 111 preclinical and 89 first-in-human) were detected by the device with 100% sensitivity and 94% specificity, automatically terminating ablation while still allowing successful ablation in all patients. Device shutoff of ablation was always faster than human response (median difference 1.24 seconds). In each of 5 sheep, 40 consecutive attempts to cause heart block by ablating over the His bundle were unsuccessful because of automatic shutoff in response to rhythm change. CONCLUSION: Automated shutoff of ablation close to the AV node in response to markers of the risk of heart block is feasible with high accuracy as well as faster response than human response. The system may improve the safety of ablation near the AV node by preventing heart block.

A study of narrow QRS tachycardia with emphasis on the clinical features, ECG, electrophysiology/radiofrequency ablation.

Aim: Atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) are the most common forms of paroxysmal regular supraventricular tachycardias. Materials & methods: The clinical, ECG and electrophysiological findings of 121 patients with narrow QRS tachycardia were evaluated prospectively. Results: A total of 75 (62%) of the patients had AVNRT while 46 (38%) had AVRT. Pounding sensation in the neck (40 vs 15.2%; p = 0.004), presynope (26.7 vs 56.5%; p = 0.001) identifiable P wave after QRS complex (25.3 vs 73.9%; p = 0.001), pseudo r'/s waves (45.3 vs 4.3%; p = 0.001), limb leads ST-T changes (34.7 vs 60.9%; p = 0.004) were the significant changes observed. A total of 94.7% of AVNRT and 87% of AVRT could be diagnosed correctly considering both clinical and ECG criteria. Conclusion: Pounding sensation in the neck and presyncope along with ECG features like identifiable P wave after QRS complex, pseudo r'/s waves and limb lead ST-T changes very accurately differentiate AVNRT and AVRT.