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Background: Electrocardiographic diagnosis of causes of supraventricular tachycardia (SVT) is sometimes difficult and application of routine algorithms can lead to misdiagnosis in as many as 37 % of patients. ST segment depression may be useful in diagnosing the nature of SVT. Methods: We reviewed surface electrocardiogram (ECG) characteristics of 300 patients having SVT with 1:1 AV relationship and correlated findings with electrophysiology study (EPS) findings. Final diagnosis of AVNRT (Atrioventricular nodal reentrant tachycardia), Orthodromic AVRT (atrioventricular reentrant tachycardia) and atrial tachycardia (AT) was correlated with ECG parameters like heart rate, ST segment depressions and QRS morphology. Results: Out of 300 patients, majority patients included in study, were having AVNRT or AVRT. ST depression predicted AVRT if the ST depression was ≥ 2 mm (overall sensitivity of 38.3 % and specificity of 93.8 % to predict AVRT) and was downsloping in morphology (sensitivity of 36.9 % and specificity of 94.7 % to predict AVRT). At heart rates ≥214 beats per minute (bpm) as measured by 7 small squares of ECG at 25 mm/s, downsloping ST depression ≥2 mm had a sensitivity 37.9 % of and specificity of 89.2 % to predict AVRT. At heart rate

A 50-year-old gentleman with old anterior wall myocardial infarction with implantable cardioverter defibrillator (ICD, Abbott Medical, Fortify ST VR 1235-40) presented with recurrent appropriate ICD shock. The ICD stored EGM indicated a possibility of supraventricular tachycardia (SVT) rather than ventricular tachycardia (VT) when the morphology match was found high. Bundle brunch re-entry (BBR) VT was another differential. An EP study conducted on antiarrhythmic drugs (AAD) induced reproducible but only ill-sustained tachycardia too short to perform any SVT maneuvers during tachycardia. However, critical analysis of the tachycardia electrograms suggested atypical AVNRT as the most likely mechanism. The other differentials were atrial tachycardia (AT) and BBR VT. Manoeuvres during sinus rhythm and ventricular pacing excluded other diagnosis. A single point radiofrequency ablation (RFA) near the SP region cured the arrhythmia. The reason for misclassification of SVT as VT was also sought for. It was found that the shocks were received due to fulfilment of 2/3 criteria (sudden onset and regular tachycardia). Hence, he received therapy despite an appropriate morphology match favouring SVT. This is one of the known limitations of ICDs where regular SVTs (AVNRT/AVRT or AT) may receive inappropriate ICD therapies. After slow pathway modification there was no further recurrence of either SVT or VT; hence, a substrate modification was deferred.

Abstract Intrahepatic interruption of the inferior vena cava (IVC) with continued hemizygous is a very rare abnormality and sometimes it may be accompanied by other cardiovascular abnormalities. Continuation of the hemizygous vein draining into the right atrium through the left superior vena cava (LSVC) is much rarer. In this paper, we have presented a patient who had simultaneous IVC interrupted with persistent LSVC and suffered from Atrioventricular nodal reentrant tachycardia (AVNRT). Finally, radiofrequencies (RF) catheter ablation for AVNRT was successfully performed through a left subclavian vein access.

Intrahepatic interruption of the inferior vena cava (IVC) with continued hemizygous is a very rare abnormality and sometimes it may be accompanied by other cardiovascular abnormalities. Continuation of the hemizygous vein draining into the right atrium through the left superior vena cava (LSVC) is much rarer. In this paper, we have presented a patient who had simultaneous IVC interrupted with persistent LSVC and suffered from Atrioventricular nodal reentrant tachycardia (AVNRT). Finally, radiofrequencies (RF) catheter ablation for AVNRT was successfully performed through a left subclavian vein access. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 69-year-old female who underwent an electrophysiological study due to recurrent supraventricular tachycardia (SVT). It highlighted the occurrence of a wide complex tachycardia (WCT) and explored the mechanism behind its transformation following a premature ventricular complex (PVC). Treatment discussed involved radiofrequency ablation targeting the base of the triangle of Koch, which successfully eliminated SVT inducibility and potentially the NFV pathway.

Supraventricular tachycardia (SVT) with ventriculoatrial (VA) block can represent a diagnostic challenge. We present a case of SVT where His-His interval shortening was repeatedly observed during episodes of VA block. This novel observation is more diagnostically suggestive of atrioventricular nodal re-entrant tachycardia, as opposed to orthodromic re-entry using a nodofascicular or nodoventricular pathway where a constant His-His is recorded during episodes of VA block. (Level of Difficulty: Intermediate.).

The article presents a case study of a 38-year-old woman with recurrent palpitations and no structural heart disease, who presented with a documented wide QRS complex tachycardia (WCT) with negative precordial concordance. It discusses the differential diagnosis of the tachycardia mechanism and the management approach, including electrophysiologic study and radiofrequency ablation.

In symptomatic children without documented supraventricular tachycardia (SVT) and non-inducible atrioventricular nodal reentry tachycardia (AVNRT) the benefit of empiric slow pathway (SP) ablation is unknown. We evaluated 62 symptomatic patients without documented SVT that underwent electrophysiology study (EPS). The purpose of this study was to determine if symptoms improved after empiric SP ablation in children without documented SVT and without inducible AVNRT. Sixty-two symptomatic patients without previously documented SVT underwent EPS; 31 (50%) had inducible AVNRT and underwent SP ablation, 20 (32%) were non-inducible and underwent empiric SP ablation, 11 (18%) were non-inducible and had no ablation. After a mean follow-up of 23 ± 18 months there was no significant difference in freedom from symptoms within the non-inducible cohort regardless of whether empiric SP ablation was performed (p = 0.135). There was a significant improvement in symptoms at follow-up after SP ablation when comparing inducible and non-inducible patients (p = 0.020). During follow-up no patients had documented SVT. Symptomatic children without documented SVT do not benefit from empiric SP ablation when AVNRT cannot be induced. [ABSTRACT FROM AUTHOR]

Background: The mechanism of typical slow‐fast atrioventricular nodal re‐entrant tachycardia (AVNRT) and its anatomical and electrophysiological circuit inside the right atrium (RA) and Koch's Triangle (KT) are not well known. Objective: To identify the potentials of the compact AV node and inferior extensions and to perform accurate mapping of the RA and KT in sinus rhythm (SR) and during AVNRT, to define the tachycardia circuit. Methods: Consecutive patients with typical AVNRT were enrolled in 12 Italian centers and underwent mapping and ablation by means of a basket catheter with small electrode spacing for ultrahigh‐density mapping and a modified signal‐filtering toolset to record the potentials of the AV nodal structures. Results: Forty‐five consecutive cases of successful ablation of typical slow‐fast AVNRT were included. The mean SR cycle length (CL) was 784.1 ± 6 ms and the mean tachycardia CL was 361.2 ± 54 ms. The AV node potential had a significantly shorter duration and higher amplitude in sinus rhythm than during tachycardia (60 ± 40 ms vs. 160 ± 40 ms, p <.001 and 0.3 ± 0.2 mV vs. 0.09 ± 0.12 mV, p <.001, respectively). The nodal potential duration extension was 169.4 ± 31 ms, resulting in a time‐window coverage of 47.6 ± 9%. The recording of AV nodal structure potentials enabled us to obtain 100% coverage of the tachycardia CL during slow‐fast AVNRT. Conclusion: Detailed recording of the potentials of nodal structures is possible by means of multipolar catheters for ultrahigh‐density mapping, allowing 100% of the AVNRT CL to be covered. These results also have clinical implications for the ablation of right‐septal and para‐septal arrhythmias. [ABSTRACT FROM AUTHOR]

The exploration of the cardiac conduction system evolved over a century, marked by groundbreaking discoveries in atrioventricular (AV) nodal physiology. Atrioventricular nodal re-entrant tachycardia (AVNRT), the most prevalent regular tachycardia in humans, remains enigmatic despite extensive research. Detailed examinations of AV nodal anatomy and histology reveal variations in location and shape, influencing electrophysiological properties. Variability in AV nodal extensions and their embryological origins contribute to the complexity of the conduction system. Physiologically, the AV node plays a crucial role in modulating AV conduction, introducing delays for ventricular filling and filtering atrial impulses. Dual-pathway physiology involving fast and slow pathways further complicates AVNRT circuitry. Integrated approaches combining pre-procedural imaging with electroanatomical mapping enhance our understanding of AV nodal structures and high-definition mapping improves precision in identifying ablation targets. Electrophysiological–anatomical correlations may unveil the specific roles of conduction axis components, aiding in the optimization of ablation strategies. This review traces the historical journey from Tawara’s pioneering work to recent integrated approaches aimed at unraveling the intricacies of AV nodal structures while emphasizing the importance of a multidimensional approach, incorporating technological advancements, anatomical understanding, and clinical validation in human mapping studies.

The article discusses a case of a 78-year-old woman undergoing catheter ablation for atrial fibrillation and presumed cavo-tricuspid isthmus-dependent atrial flutter. The focus is on the para-Hisian pacing maneuver during the procedure, examining different paced QRS morphologies and their interpretation, highlighting the importance of confirming what is being captured by the pacing electrode and discussing the observed responses.

Background: Several studies have visualized the slow pathway during sinus rhythm using high-density mapping of Koch's triangle (KT) in patients with atrioventricular nodal reentrant tachycardia (AVNRT). However, it is unclear whether the slow pathway can be visualized in all people. Therefore, we evaluated the activation pattern within KT during sinus rhythm in patients with and without AVNRT. Methods: High-density mapping using the Advisor HD Grid mapping catheter (Abbott) within KT during sinus rhythm was created in 10 patients with slow-fast AVNRT and 30 patients without AVNRT. Results: In 8 (80%) patients with AVNRT, the activation pattern pivoting around a block line (BL) within KT was observed. In 12 (40%) patients without AVNRT, similar activation pattern pivoting around BL was observed, but jump was observed in 11 (92%) of these patients. In all patients, the activation pattern pivoting around BL was observed in 17 (85%) of 20 patients with jump, but only 3 (15%) of 20 patients without jump (p < 0.0001). During jump, there was a long period of no potential from the last atrial potential within KT to the His bundle potential, suggesting the slow pathway conduction through the rightward inferior extension that cannot be visualized. A linear ablation between the pivot point and the septal tricuspid annulus was successful for slow-fast AVNRT. Conclusion: Although the slow pathway could not be visualized using high-density mapping during sinus rhythm, the activation pattern pivoting around BL within KT was observed in most patients with the dual pathway physiology, with or without AVNRT. [ABSTRACT FROM AUTHOR]

The article describes the case of a 45-year-old gentleman with documented narrow QRS tachycardia and structurally normal heart who underwent electrophysiology study with the intent of radiofrequency ablation. Topics include observation on the narrow QRS tachycardia, differential diagnosis for this narrow QRS tachycardia, and analysis of the repeated termination of the tachycardia after the subsequent His which occurred on time with His refractory ventricular premature depolarization (VPD).

Aim: Paroxysmal supraventricular tachycardia (PSVT), particularly atrioventricular nodal reentrant tachycardia (AVNRT), is a common arrhythmia with no associated structural heart disease. Inflammation has been implicated in the pathogenesis of arrhythmias. Uric acid to high density lipoprotein (HDL)-cholesterol ratio (UHR) is a novel inflammation marker that has been investigated in various conditions. This study aimed to explore the potential association between UHR and AVNRT. Materials and Methods: A total of 136 patients were included in the study, including 86 patients with AVNRT and 50 controls with normal electrophysiological study. All patients' medical records were reviewed, and data were obtained retrospectively. We recorded baseline features, hematologic and biochemical markers, and determined the UHR value. Results: UHR (p=0.031) and uric acid (p<0.001) levels were significantly higher, while HDL cholesterol (p=0.031) levels were significantly lower in the AVNRT group. Neutrophil leukocyte ratio (NLR) was also higher in the AVNRT group (p=0.034). However, in multivariate analysis, only UHR emerged as an independent predictor for AVNRT (OR: 1.088; 95%CI: 1.022 - 1.159; p=0.008). ROC curve analysis suggested a UHR cut-off > 14.05 for predicting AVNRT with 56% sensitivity and 76% specificity. Conclusion: This study identifies UHR as a promising predictor for AVNRT, shedding light on the potential role of inflammation in the arrhythmia's development. Utilizing UHR as a readily accessible marker in the evaluation of AVNRT patients may have clinical implications. [ABSTRACT FROM AUTHOR]

Radiofrequency (RF) catheter ablation is an effective treatment option for targeting the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT). Previous data suggested that using intracardiac echocardiography (ICE) guidance could improve procedural outcomes when compared to using fluoroscopy alone. In this prospective study, we aimed to compare the effectiveness of an electroanatomical mapping system (EAMS)-guided approach with an ICE-guided approach for SP ablation. Eighty patients undergoing SP ablation for AVNRT were randomly assigned to either the ICE-guided or EAMS-guided group. If the procedural endpoint was not achieved after 8 RF applications; patients were allowed to crossover to the ICE-guided group. The ICE-guided approach reduced the total procedure time (61.0 (56.0; 66.8) min vs. 71.5 (61.0; 80.8) min, p < 0.01). However, the total fluoroscopy time was shorter (0 (0–0) s vs. 83.5 (58.5–133.25) s, p < 0.001) and the radiation dose was lower (0 (0–0) mGy vs. 3.3 (2.0–4.7) mGy, p < 0.001) with EAMS-guidance. The ICE-guided group had a lower number of RF applications (4 (3–5) vs. 5 (3.0–7.8), p = 0.03) and total ablation time (98.5 (66.8–186) s vs. 136.5 (100.5–215.8) s, p = 0.02). Nine out of 40 patients (22.5%) in the EAMS-guided group crossed over to the ICE-guided group, and they were successfully treated with similar RF applications in terms of number, time, and energy compared to the ICE-guided group. There were no recurrences during the follow-up period. In conclusion, the utilization of ICE guidance during SP ablation has demonstrated notable reductions in procedural time and RF delivery when compared to procedures guided by EAMS. In challenging cases, an early switch to ICE-guided ablation may be the optimal choice for achieving successful treatment. [ABSTRACT FROM AUTHOR]

A 51‐year‐old female with congenitally corrected transposition of great arteries (CCTGA), situs solitus, dextrocardia, atrial septal defect and persistent left superior vena cava underwent electrophysiology study for recurrent palpitations with documented narrow complex, short RP tachycardia. With a catheter in the region of the anterior mitral annulus, a His signal was recorded and HV interval was 35 msec. Tachycardia was induced with a ventricular extrastimulus. During the tachycardia there was 1:1 ventriculo‐atrial conduction and central atrial activation with a VA interval of 20 msec. The recorded His signal could be seen after the QRS. What is the mechanism of the tachycardia? [ABSTRACT FROM AUTHOR]

Background: Catheter ablation of atrioventricular nodal reentry tachycardia (AVNRT) using a traditional anatomic approach is effective and generally safe, but recurrence can be up to 9% and there is a risk for high degree AV block. The objective of the present study is to investigate the utility of a novel mapping approach using the Abbott EnSite™ X EP System and a multi-electrode mapping catheter, Advisor™ HD Grid Mapping Catheter, Sensor Enabled™, for slow pathway visualization via fractionation mapping during sinus rhythm. Methods: 11 patients with typical slow-fast AVNRT based on EP study were included in this study. Koch's triangle was mapped using EnSite™ X EP System and Advisor™ HD Grid Mapping Catheter, Sensor Enabled™ during sinus rhythm with pre-set AutoMap Fractionation settings. Sites of slow pathway potentials are uniquely identified and displayed as fractionation points. Radiofrequency (RF) energy was then delivered for targeted therapy of the identified slow pathway sites. Results: Successful ablation was achieved in all patients with no complications. The average number of ablations delivered was 5.0 ± 2.4. The average length of total RF ablation time was 106.1 ± 47.5 seconds with Power of 30.5 ± 1.6 W. The mean mapping time was 5 mins 35 seconds ± 1 min 39 seconds. The average total mapping points were 9695.8 ± 4533.1. For all patients, discrete fractionation signals were identified in slow pathway sites, which were displayed as slower wave speed conduction (< 1.5 m/s) on wave speed maps and fractionation maps. Conclusion: We described a novel high-density mapping approach using EnSite™ X EP System and a multi-electrode mapping catheter, Advisor™ HD Grid Mapping Catheter, Sensor Enabled™, to allow for direct visualization of slow pathway signals via fractionation mapping, thereby enabling successful ablation therapy with potentially a better safety profile and improved outcome. Larger studies are needed to further confirm our observations. [ABSTRACT FROM AUTHOR]

Multispline catheters were recently introduced and have led to significant improvements in electrogram acquisition and analysis. Omnipolar mapping is now able to be performed with these multispline catheters. Omnipolar mapping has the advantages of mapping a focal segment without needing the entire chamber of interest to be mapped, does not need a stable reference and is cycle length independent. This article will review the mechanism of omnipolar mapping and show how this technology can be used for multiple arrythmias. [ABSTRACT FROM AUTHOR]

Wrist-worn devices are popular for heart rate monitoring, including use of photoplethysmography. The Apple Watch series 4 can identify atrial fibrillation. We describe a case of identification re-entrant supraventricular tachycardia not identified by outpatient rhythm monitoring, however, was identified by the Apple Watch series 4, which lead to electrophysiology study and successful ablation of atrioventricular nodal re-entrant tachycardia.

BackgroundDuring slow pathway modification for atrioventricular nodal reentrant tachycardia, heart block may occur if ablation cannot be stopped in time in response to high risk electrogram features (HREF).ObjectivesTo develop an automatic algorithm to monitor HREF and terminate ablation earlier than human reaction.MethodsDigital electrogram data from 332 ablation runs from February 2020 to June 2022 were included. They were divided into training and validation sets which contained 126 and 206 ablation runs respectively. HREF in training set was measured. Then a program was developed with cutoff values decided from training set to capture all these HREF. Simulation ablation videos were rendered using validation set electrogram data. The videos were played to three independent electrophysiologists who each determined when to stop ablation. Timing of ablation termination, sensitivity, and specificity were compared between human and program.ResultsReasons for ablation termination in the training set include short AA time, short VV time, AV block and VA block. Cutoffs for the program were set to maximize program sensitivity. Sensitivity and specificity for the program in the validation set were 95.2% and 91.1% respectively, which were comparable to that of human performance at 93.5% and 95.4%. If HREF were recognized by both human and program, ablations were terminated earlier by the program 90.2% of times, by a median of 574 ms (interquartile range 412–807 ms, p

Abstract Background Post-cardiac injury syndrome (PCIS) is an inflammatory condition following myocardial or pericardial damage. In response to catheter ablation, PCIS most frequently occurs after extensive radiofrequency (RF) ablation of large areas of atrial myocardium. Minor myocardial injury from right septal slow pathway ablation for atrioventricular nodal reentrant tachycardia (AVNRT) is not an established cause of the syndrome. Case presentation A 62-year-old women with a 6-year history of symptomatic narrow-complex tachycardia was referred to perform an electrophysiological study. During the procedure AVNRT was recorded and a total of two RF burns were applied to the region between the coronary sinus and the tricuspid annulus. Pericardial effusion was routinely ruled out by focused cardiac ultrasound. In the following days, the patient developed fever, elevated inflammatory and cardiac markers, new-onset pericardial effusion, characteristic ECG changes, and complained of pleuritic chest pain. An extensive workup for infectious, metabolic, rheumatologic, neoplastic, and toxic causes of pericarditis and myocarditis was unremarkable. Cardiac magnetic resonance imaging showed no signs of ischemia, infiltrative disease or structural abnormalities. The patient was diagnosed with PCIS and initiated on aspirin and low-dose colchicine. At a 1-month follow-up visit the patient was free of symptoms but still had a small pericardial effusion. After three months of treatment the pericardial effusion had resolved completely. Conclusions Inflammatory pericardial reactions can occur after minor myocardial damage from RF ablation without involvement of structures in close proximity to the pericardium.

The article presents a case study of a 72-year-old woman who underwent a diagnostic three-wire electrophysiology study. The woman had a history of tachycardia with left bundle branch block (LBBB) morphology, and after a pathway modification, she developed an incessant tachycardia (TCL). The woman's Atrial-His-His Atrial (AHHA) response measurement demonstrates the link of the first His after atrial pacing termination to the penultimate beat in the drive train rather than the final beat.

Introduction: Catheter ablation (CA) of atrioventricular nodal reentrant tachycardia (AVNRT) is associated with late pacemakers for AV block (AVB). We performed a systematic review and meta‐analysis of the pooled incidence of late pacemakers for AVB after CA of AVNRT. Methods and Results: Relevant studies were identified from four electronic databases (PubMed, EMBASE, Scopus, and Cochrane Trial Register) from inception to 2022. A random effects model was used to calculate the odds of late pacemakers in CA of AVNRT compared to atrioventricular reentrant tachycardia (AVRT). Of 533 articles screened, 13 were included in systematic review. CA for AVNRT was performed in 16 471 patients (mean age 54 ± 17 years, 63% females), of which 68 (0.4%) underwent pacemaker implantation for late AVB. Meta‐analysis was performed in 5 of the 13 studies (mean follow‐up duration 7 ± 4 years). Patients who underwent CA of AVNRT were older (58 ± 17 vs. 52 ± 20 years, p <.001), and more likely female (60% vs. 41%, p <.001) than AVRT. Pooled estimates of late pacemakers for AVB were higher in CA of AVNRT than AVRT (0.5% vs. 0.2%, p =.006), with CA in AVNRT associated with almost twofold increased odds of late pacemakers indicated for AVB (odds ratio: 1.94, 95% confidence interval: 1.08–3.47, p =.027) compared to AVRT. Conclusion: AVNRT ablation is safe but associated with a low but definitely increased risk of requiring pacing in the later years due to AVB. This association is confirmed by pooling over 16 000 AVNRT patients receiving clinically indicated ablation and is helpful in providing informed consent for prospective patients undergoing ablation for AVNRT. [ABSTRACT FROM AUTHOR]

The exploration of the cardiac conduction system evolved over a century, marked by groundbreaking discoveries in atrioventricular (AV) nodal physiology. Atrioventricular nodal re-entrant tachycardia (AVNRT), the most prevalent regular tachycardia in humans, remains enigmatic despite extensive research. Detailed examinations of AV nodal anatomy and histology reveal variations in location and shape, influencing electrophysiological properties. Variability in AV nodal extensions and their embryological origins contribute to the complexity of the conduction system. Physiologically, the AV node plays a crucial role in modulating AV conduction, introducing delays for ventricular filling and filtering atrial impulses. Dual-pathway physiology involving fast and slow pathways further complicates AVNRT circuitry. Integrated approaches combining pre-procedural imaging with electroanatomical mapping enhance our understanding of AV nodal structures and high-definition mapping improves precision in identifying ablation targets. Electrophysiological-anatomical correlations may unveil the specific roles of conduction axis components, aiding in the optimization of ablation strategies. This review traces the historical journey from Tawara's pioneering work to recent integrated approaches aimed at unraveling the intricacies of AV nodal structures while emphasizing the importance of a multidimensional approach, incorporating technological advancements, anatomical understanding, and clinical validation in human mapping studies.

Background: Selection of radiofrequency ablation (RF) or cryoablation (Cryo) for atrioventricular nodal re-entrant tachycardia (AVNRT) in children remains controversial due to a lack of contemporary comparison studies in this population., Objectives: This study sought to compare outcomes of RF and Cryo for AVNRT in the pediatric population., Methods: AVNRT ablation outcomes were retrospectively analyzed utilizing the National Cardiovascular Data Registry IMPACT (Improving Pediatric and Adult Congenital Treatment) Registry from April 2016 to March 2019. Data from subjects 1 to 21 years of age undergoing elective first-time slow pathway (SP) modification for AVNRT were included. Exclusion criteria included <1 year of age, congenital heart disease, and >1 ablation target. Cases were analyzed by ablation energy: 1) RF only; 2) Cryo only; 3) radiofrequency ablation switching to cryoablation (RF→Cryo); and 4) cryoablation switching to radiofrequency ablation (Cryo→RF). The primary outcome was acute ablation failure. Secondary outcomes included in-hospital adverse events., Results: Among 2,448 patients (mean age 13.6 ± 3.4 years, 60% female), RF only was employed in 43% (n = 1,046), Cryo only in 49% (n = 1,201), RF→Cryo in 6% (n = 135), and Cryo→RF in 66 (3%). Acute ablation failure occurred in 1.3% (n = 33), with no difference by energy source (1% in RF only, 1.5% in Cryo only, 1.5% in RF→Cryo, 3% in Cryo→RF; P = 0.5). Atrioventricular (AV) block requiring permanent pacemaker did not occur in any group; transient AV block occurred in 0.4% of the cohort, with no difference by group., Conclusions: In this largest pediatric study of AVNRT ablation, RF and Cryo demonstrated comparable high acute success and rare documentation of AV block that did not result in temporary or permanent pacing. Longitudinal data are important for further comparison of these modalities with regard to recurrence risk and late complications., Competing Interests: Funding Support and Author Disclosures The specific analysis described in this manuscript was funded by the American College of Cardiology and National Cardiovascular Data Registry. The proposed project and manuscript were reviewed by the IMPACT Research and Publications Committee. The funding agencies had no role in the drafting of the manuscript or influencing its content. The views expressed in this manuscript represent those of the author(s), and do not necessarily represent the official views of the NCDR or its associated professional societies identified at CVQuality.ACC.org/ NCDR. The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

A 50-year-old gentleman with old anterior wall myocardial infarction with implantable cardioverter defibrillator (ICD, Abbott Medical, Fortify ST VR 1235-40) presented with recurrent appropriate ICD shock. The ICD stored EGM indicated a possibility of supraventricular tachycardia (SVT) rather than ventricular tachycardia (VT) when the morphology match was found high. Bundle brunch re-entry (BBR) VT was another differential. An EP study conducted on antiarrhythmic drugs (AAD) induced reproducible but only ill-sustained tachycardia too short to perform any SVT maneuvers during tachycardia. However, critical analysis of the tachycardia electrograms suggested atypical AVNRT as the most likely mechanism. The other differentials were atrial tachycardia (AT) and BBR VT. Manoeuvres during sinus rhythm and ventricular pacing excluded other diagnosis. A single point radiofrequency ablation (RFA) near the SP region cured the arrhythmia. The reason for misclassification of SVT as VT was also sought for. It was found that the shocks were received due to fulfilment of 2/3 criteria (sudden onset and regular tachycardia). Hence, he received therapy despite an appropriate morphology match favouring SVT. This is one of the known limitations of ICDs where regular SVTs (AVNRT/AVRT or AT) may receive inappropriate ICD therapies. After slow pathway modification there was no further recurrence of either SVT or VT; hence, a substrate modification was deferred., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Indian Heart Rhythm Society. Published by Elsevier B.V. All rights reserved.)

Background: Electrocardiographic diagnosis of causes of supraventricular tachycardia (SVT) is sometimes difficult and application of routine algorithms can lead to misdiagnosis in as many as 37 % of patients. ST segment depression may be useful in diagnosing the nature of SVT., Methods: We reviewed surface electrocardiogram (ECG) characteristics of 300 patients having SVT with 1:1 AV relationship and correlated findings with electrophysiology study (EPS) findings. Final diagnosis of AVNRT (Atrioventricular nodal reentrant tachycardia), Orthodromic AVRT (atrioventricular reentrant tachycardia) and atrial tachycardia (AT) was correlated with ECG parameters like heart rate, ST segment depressions and QRS morphology., Results: Out of 300 patients, majority patients included in study, were having AVNRT or AVRT. ST depression predicted AVRT if the ST depression was ≥ 2 mm (overall sensitivity of 38.3 % and specificity of 93.8 % to predict AVRT) and was downsloping in morphology (sensitivity of 36.9 % and specificity of 94.7 % to predict AVRT). At heart rates ≥214 beats per minute (bpm) as measured by 7 small squares of ECG at 25 mm/s, downsloping ST depression ≥2 mm had a sensitivity 37.9 % of and specificity of 89.2 % to predict AVRT. At heart rate <214 bpm, downsloping ST depression ≥2 mm had sensitivity of 37.2 % and specificity of 96.5 % to predict AVRT. Downsloping ST depression of ≥2 mm helps to differentiate AVNRT from AVRT., Conclusion: A downsloping ST segment depression ≥2 mm predicted SVT being an AVRT and can be used as a useful criteria in diagnosing the tachycardia., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Indian Heart Rhythm Society. Published by Elsevier B.V. All rights reserved.)

Cardiac arrhythmias occurring during pregnancy pose a therapeutic problem as antiarrhythmic drugs can be potentially harmful to the fetus. A 35-years-old woman in the 20th week of pregnancy was admitted to the Department of Cardiology due to the first episode of arrhythmia in her life. During the event, the patient was wearing an Apple Watch Series 6, which records a 30-sec single-channel ECG. The recording showed narrow QRS complex tachycardia of 216 bpm, and short RP interval and atrioventricular nodal reentrant tachycardia (AVNRT) was recognized. Due to the mild nature of the arrhythmia, antiarrhythmic pharmacotherapy was not initiated. The use of mobile health (mHealth) devices such as wearables and health monitoring applications is now a valuable addition to routine cardiac diagnostics for patients of all ages and levels of cardiovascular risk.

Introduction: Ablation for atrioventricular nodal reentrant tachycardia (AVNRT) classically utilizes evaluation of signal morphology within the anatomic region of the slow pathway (SP), which involves subjectivity. Ripple mapping (RM; CARTO‐3© Biosense Webster Inc) displays each electrogram at its three‐dimensional coordinate as a bar changing in length according to its voltage–time relationship. This allows prolonged, low‐amplitude signals to be displayed in their entirety, helping identify propagation in low‐voltage areas. We set out to evaluate the ability of RM to locate the anatomic site of the SP and assess its use in guiding ablation for AVNRT. Methods: Patients ≤18 years with AVNRT in the EP laboratory between 2017 and 2021 were evaluated. RM was performed to define region of SP conduction in patients from 2019 to 2021, whereas standard electro‐anatomical mapping was used from 2017 to 2019. All ablations were performed using cryotherapy. Demographics, outcomes, and analysis of variance in number of test lesions until success was compared between groups. Results: A total of 115 patients underwent AVRNT ablation during the study; 46 patients were in the RM group and 69 were in the control group. There were no demographic differences between groups. All procedures, in both groups, were acutely successful. In RM group, 89% of first successful lesions were within 4 mm of the predicted site. There was significantly reduced variability in number of test lesions until success in the RM group (p =.01). Conclusion: RM is a novel technique that can help identify SP location, allowing for successful ablation of AVNRT with decreased variability. [ABSTRACT FROM AUTHOR]

The article presents the case of a 19-year-old male patient with rheumatic heart disease, post mitral valve replacement three years earlier, presented with recurrent episodes of palpitations and whose ECG showed regular wide complex tachycardia (WCT) at a rate of 140 beats per minute (bpm) with QRS identical to sinus rhythm. Topics discussed include findings of his ventricular pacing, and clinical findings on the patient's tachycardia.

The article describes the case of a 20-year-old male with an implantable cardioverter-defibrillator (ICD) that had been implanted seven years ago due to recurrent and failed ablation for fascicular left ventricular tachycardia. Topics include results of electrophysiological study and differential diagnosis of narrow complex tachycardia (NCT) with ventriculoatrial (VA) dissociation or variable block to the atrium.

A 37-year-old female with dilated cardiomyopathy, whose baseline ECG showed sinus rhythm with left bundle branch block pattern, received a cardiac resynchronization therapy defibrillator (CRTD). One week post-implantation, she presented to the emergency department with palpitations, diaphoresis and chest discomfort. ECG showed a wide-complex tachycardia (WCT) episode, which spontaneously converted to sinus rhythm, and was later diagnosed as typical slow-fast atrioventricular nodal re-entrant tachycardia. This report outlines the differential diagnoses for WCT and the reasoning behind the eventual diagnosis, taking into consideration the device interrogation findings and results of the electrophysiology study. [ABSTRACT FROM AUTHOR]

Purpose: The incidence of atrial flutter following radiofrequency ablation of supraventricular tachycardias is poorly understood. Ablation of atrioventricular nodal reentry tachycardia may place patients at risk of flutter because ablation of the slow pathway is in close proximity to the cavotricuspid isthmus. This study aims to evaluate the risk of atrial flutter following ablation of atrioventricular nodal reentry tachycardia relative to ablation of other supraventricular tachycardias.Methods: A single-center retrospective analysis was completed for all supraventricular tachycardia ablations performed between July 2006 and July 2016. Patient and procedural details were collected for 544 patients who underwent atrioventricular nodal reentry tachycardia ablation (n = 342), atrioventricular reentry tachycardia ablation (n = 125), or atrial tachycardia ablation (n = 60). Follow-up for flutter after ablation of their incident arrhythmia was assessed.Results: Patients who underwent atrioventricular nodal reentry tachycardia ablation were more likely to develop CTI-dependent flutter than patients who underwent ablation of other supraventricular tachycardias (4.97% vs. 0%; p = 0.002). Compared with patients who did not develop flutter, patients who developed flutter after atrioventricular nodal reentry tachycardia ablation were more likely to have undergone ablation of atypical atrioventricular nodal reentry tachycardia (11.8% vs. 2.15%; p = 0.016).Conclusions: We identified an association between atrioventricular nodal reentry tachycardia ablation and development of CTI-dependent atrial flutter. This finding may have implications for the management and follow-up after atrioventricular nodal reentry tachycardia ablation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate nature of AV nodal activation in patients with AVNRT using high density electro-anatomic mapping (HD-EAM). Methods: HD-EAM was created in 30 patients with AVNRT from the triangle of Koch (ToK) in sinus rhythm (SR). Isochronal late activation maps (ILAM) were created. EAMs were analyzed for slow pathway (SPW) and fast pathway (FPW) activation. A pivot point (PP) was defined where FPW and SPW collided and pivoted back to the AV node (AVN). Conduction was assessed with programmed extrastimulus (PES) in 9 patients until FPW refractory period (ERP). The change in PP distance from the HIS (ΔPP) was measured in SR and PES. The ΔPP was compared to ΔAH. The PP was ablated and SR re-mapped. Results: The FPW activates the His and moves inferiorly toward the coronary sinus (CS). Activation also enters the ToK near the CS and collides with the FPW which then pivots around a functional line of block (LOB) within the ToK and moves superiorly along the septal tricuspid annulus. PP electrograms are fractionated, low amplitude, and consistent with SPW potentials (Haissaguerre et al. in Circulation 85:2162–2175, 1992). During PES the PP moved superiorly until FPW ERP when only SPW activation occurs. Normalized ΔAH and ΔPR vs ΔPP was highly correlated p < 0.0001. Ablation at the PP was successful and associated with loss of SPW fusion and pivot. Conclusion: We conclude HD-EAM/ILAM provide a novel method for localizing the SPW in SR. This study provides further understanding of dual AV nodal physiology and may aid in targeting the SPW for ablation of AVNRT. [ABSTRACT FROM AUTHOR]

Background: Left-sided ablation, targeting left inferior AV nodal extensions, is thought to be necessary for success in a small proportion of atrioventricular nodal re-entrant tachycardia (AVNRT) ablations; however Indian data are scarce in this regard. Methods: Consecutive cases of AVNRT undergoing slow pathway ablation in a single centre over an 18-month period were retrospectively analyzed. Left-sided ablation at the posteroseptal mitral annulus was performed if right-sided ablation failed to abolish AVNRT. Results: From January 2017 to June 2018, out of 215 consecutive supraventricular tachycardia (SVT) cases, 154 (71.6%) were AVNRT (47.1 ± 13.1 years, 46.1% male). Trans-septal ablation was required in 5 (3.2%) cases (mean age 48.8 ± 9.4 years; 4 female, 1 male); all with typical (slow-fast) form of AVNRT. Compared with cases needing only right-sided ablation, radiofrequency time (50.8 ± 16.9 vs. 9.9 ± 8.5 min; p = 0.005) and procedure time (166.0 ± 35.0 vs 79.6 ± 35.9 min; p = 0.004) were significantly longer for trans-septal cases, while baseline intervals and tachycardia cycle length were not significantly different. Junctional ectopy was seen in only 2 of the 5 cases during left-sided ablation, but acute success (non-inducibility) was obtained in 3 cases. There were no instances of AV block. Over mean follow-up of 12.2 ± 4.0 months, clinical recurrence of AVNRT occurred in one case, while others remained arrhythmia-free without medication. Conclusion: Left-sided ablation was required in a small proportion of AVNRT ablations. Trans-septal approach targeting the posteroseptal mitral annulus was safe and yielded good mid-term clinical success.

The article describes the case of a 30-year-old man with a structurally normal heart and with a two-year-history of recurrent episodes of rapid paroxysmal palpitations. Topics discussed include the diagnosis of the patient during electrophysiology (EP) study done twice before in other hospitals, confirmation of the diagnosis of fascicular ventricular tachycardia (VT), and the least common type among the idiopathic fascicular VTs.

Background: Vagal Maneuver is an underutilized strategy for Cardioversion of Atrioventricular nodal reentrant tachycardia. The present study is an attempt to explore the effectiveness of this strategy. Methods: This comparative cross-sectional study was performed at the Department of Cardiology MTI MMC Mardan from the first January 2017 to 31 December 2019. Patients with Palpitations and having documented AVNRT on ECG were selected for this study. Patients were divided into two groups, i.e., Group A and Group B through envelope method. Patients in Group A were subjected to vagal maneuvers like carotid sinus massage, and Valsalva methods. Patients in Group B received injection verapamil 5 mg. Results: A sample size of 100 patients were enrolled. The mean age was 31 with 8.6SD. Male were 54% and females were 46%. The success rate of vagal maneuvers in group A was 36% (n=18), while in group B, it was 84% (n=42) for verapamil (36% vs 84%, p-value<0.001, highly significant). In group A, time for cardioversion in less than 2 minutes was 68%. While in group B, the time for cardioversion in less than two minutes was 12%. ( 68% vs 12%, p<0.001, highly significant).Cross over in Group A was 64% (n=32) to verapamil. While in group B, this was 6% (n=3) to DC shock and 14% (n=7) to vagal maneuvers (64% vs 18%, p<0.001, highly significant.) Conclusion: Simple Valsalva Maneuvers and verapamil proved to be effective in cardioversion of SVT/AVNRT. Both are safe. Verapamil is more successful in cardioversion as compared to Valsalva maneuvers. [ABSTRACT FROM AUTHOR]

Background: Post-cardiac injury syndrome (PCIS) is an inflammatory condition following myocardial or pericardial damage. In response to catheter ablation, PCIS most frequently occurs after extensive radiofrequency (RF) ablation of large areas of atrial myocardium. Minor myocardial injury from right septal slow pathway ablation for atrioventricular nodal reentrant tachycardia (AVNRT) is not an established cause of the syndrome.Case Presentation: A 62-year-old women with a 6-year history of symptomatic narrow-complex tachycardia was referred to perform an electrophysiological study. During the procedure AVNRT was recorded and a total of two RF burns were applied to the region between the coronary sinus and the tricuspid annulus. Pericardial effusion was routinely ruled out by focused cardiac ultrasound. In the following days, the patient developed fever, elevated inflammatory and cardiac markers, new-onset pericardial effusion, characteristic ECG changes, and complained of pleuritic chest pain. An extensive workup for infectious, metabolic, rheumatologic, neoplastic, and toxic causes of pericarditis and myocarditis was unremarkable. Cardiac magnetic resonance imaging showed no signs of ischemia, infiltrative disease or structural abnormalities. The patient was diagnosed with PCIS and initiated on aspirin and low-dose colchicine. At a 1-month follow-up visit the patient was free of symptoms but still had a small pericardial effusion. After three  months of treatment the pericardial effusion had resolved completely.Conclusions: Inflammatory pericardial reactions can occur after minor myocardial damage from RF ablation without involvement of structures in close proximity to the pericardium. [ABSTRACT FROM AUTHOR]

Background: Apart from junctional rhythms during slow pathway ablation, there is limited knowledge about the junctional tachycardia persisting following ablation cessation. This study is conducted to determine the characteristics and significance of this rare arrhythmia. Methods and results: This study was done on 487 patients with AVNRT undergoing the radiofrequency ablation. The RF delivery‐induced Supraventricular Tachycardia, persisting for a few minutes following the termination of ablation (post‐ablation SVT) was investigated in this research. Atrial Overdrive Pacing (AOP) was applied to the post‐ablation SVT to distinguish AVNRT from Junctional Tachycardia(JT). A total of 2337 RF‐current deliveries were applied, and post‐ablation SVT was observed in 81 of them. According to the electrophysiological studies, five of them (in five separate cases) were definitely diagnosed as JT. The overall incidence of post‐ablation JT was about 1% of all patients. In these cases, RF energy was applied to the posteroseptal region and roof of the proximal coronary sinus. The mean Cycle Length (CL) of JTs was equal to 446 ±67ms. Following post‐ ablation JT termination, four cases met endpoints of successful ablation, demonstrating a positive predictive value of 80%. Atrioventricular (AV) block did not occur in any of the cases and reappearance of JT was not observed during procedure or mean follow‐up period of 19.8 ± 8.4 months. Conclusions: Post‐ablation JT is probably a transient Ischemia‐induced arrhythmia that does not require further ablation. Thus, it is recommended to differentiate between the AVNRT and JT in post‐ablation arrhythmias to avoid unnecessary RF application. [ABSTRACT FROM AUTHOR]

Background. The ST-segment is part of the electrocardiogram and physiologically, it forms an isoelectric line. The ST-segment depression is often observed in young, healthy people with paroxysmal tachycardia with narrow QRS complexes. In this group of patients, the 'mysterious tachycardia-induced ST-segment depression', 'subendocardial myocardial ischemia' and other not fully understood terms are used to explain this phenomenon. Objectives. To assess the presence and possible mechanisms of ST-segment depression during atrioventricular nodal reentrant tachycardia (AVNRT) in patients undergoing radiofrequency (RF) ablation of the underlying arrhythmia. Materials and methods. The study included 50 patients (35 women and 15 men) aged about 49 years with clinically relevant paroxysmal narrow QRS complex tachycardia. During electrophysiological study (EPS), all patients had measured QRS components -- QR, RS and RJ during the tachycardia and during the sinus rhythm. All of the measurements were done in lead V5. Results. There was a statistically significant difference in cycle length during sinus rhythm and tachycardia (707.0 ±137.8 ms compared to 327.5 ±29.1 ms, p = 0.000), the RJ component (0.819 ±0.381 mV compared to 0.878 ±0.376 mV, p = 0.003) and the difference RJ-QR (0.081 ±0.083 mV compared to 0.163 ±0.108 mV, p = 0.000). The differences in RS and QR components during sinus rhythm and tachycardia did not reach the statistical significance. The difference RJ-QR during tachycardia correlated negatively with tachycardia cycle length (R = -0.39, p = 0.0049). The tachycardia cycle length correlated positively with the age of the studied patients (R = 0.28, p = 0.043). Conclusions. In patients with AVNRT, there is a ST-segment depression during the episodes of tachycardia and the degree of this change is related to tachycardia cycle length. The most probable explanation of the STsegment depression is the overlap of the QRS complex on the preceded T wave. Some intrinsic properties of individual electrocardiogram (ECG) also influence this phenomenon. The ischemic origin of the presented ST-segment change can be excluded. [ABSTRACT FROM AUTHOR]

Abstract Background Variability in the anatomy and orientation of the triangle of Koch (TK) complicates ablation procedures involving the atrioventricular (AV) node. We used CT angiography (CTA) to assess the anatomical TK orientation, the CS ostium direction, and the relationship between the two, and we validated an individualized CS-guided projection during ablation procedures. Methods In 104 patients without structural heart disease undergoing computed tomography (CT) angiography, TK orientations were determined in relation to the coronary sinus ostium (CSo) as well as two standard right anterior oblique (RAO) projection angles (30o and 45o) commonly used in ablation procedures. Results A CS-guided RAO projection (RAOCS) was shown to best track the orientation of the TK compared to RAO30° and 45°, with TK orientation strongly correlating with the CSo direction (r = 0.86, P