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Background: Low‐to‐zero fluoroscopic navigation systems lower radiation exposure which improves health outcomes. Conventional x‐ray fluoroscopy (CF) has long been the standard to guide to catheter location for cardiac ablation. With advancements in technology, alternative safety navigation systems have been developed. Three primary modalities commonly utilized are three‐dimensional electroanatomic mapping (3D‐EAM), magnetic navigation system (MNS), and intracardiac echocardiography (ICE), all of which can reduce radiation exposure during the procedure. Objective: We aim to compare the efficacy and safety among ICE, EAM, MNS, and CF in ablation of atrioventricular nodal reentrant tachycardia (AVNRT). Methods: This is a meta‐analysis consisting of observational studies and randomized controlled trials, which evaluated the performance of navigation systems of catheter ablation in AVNRT patients. Primary endpoint was to access the AVNRT recurrence after the procedure during follow‐up periods. Secondary endpoints were technical success, fluoroscopic time, fluoroscopic dose area product, radiofrequency ablation time, and adverse events. Random‐effect model was applied for pooled estimated effects of included studies. Results: A total of 21 studies (21 CF, 2 ICE, 9 EAM, 11 MNS) including 1716 patients who underwent catheter ablation for AVNRT treatment were analyzed. Of these, 16 were observational studies and 5 were randomized controlled trials. Primary outcome: Point estimation of AVNRT recurrence showed ICE exhibited a pooled odds ratio (ORs) of 1.06 (95% confidence interval [CI]: 0.064–17.322), MNS with ORs of 0.51 (95% CI: 0.214–1.219], and EAM with ORs of 0.394 (95% CI: 0.119–1.305) when compared to CF. Secondary outcomes: EAM had significant higher technical success with ORs of 2.781 (95% CI: 1.317–5.872) when compared to CF. Regarding fluoroscopy time, EAM showed the lowest time with mean differences (MD) of −10.348 min (95% CI: −13.385 to −7.3101) and P‐score of 0.998. It was followed by MNS with MD of −3.712 min (95% CI: −7.128 to −0.295) and P‐score of 0.586, ICE with MD of −1.150 min (95% CI: −6.963 to 4.662) with a P‐score of 0.294 compared to CF, which has a P‐score of 0.122. There were insignificant adverse events across the procedures. Conclusion: AVNRT ablation navigated by low‐to‐zero fluoroscopic navigation systems achieves higher efficacy and comparable safety to conventional fluoroscopywhile also reducing risk of radiation exposure time. [ABSTRACT FROM AUTHOR]

Introduction: The decremental properties of the nodoventricular pathway (NVP) are uncertain. Methods and Results: During short RP supraventricular tachycardia, a His‐refractory premature ventricular contraction (PVC) consistently terminated the tachycardia without atrial capture immediately after the PVC. Whereas a slightly earlier PVC failed to reset the subsequent His but terminated the tachycardia without atrial capture one cycle later. Conclusion: These observations are diagnostic of slow‐fast atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed‐NVP and can be explained by decremental properties in the NVP itself; greater prematurity of the PVC resulted in more decremental conduction over the NVP, causing the AVNRT termination one cycle later. [ABSTRACT FROM AUTHOR]

The article present case study of a 63‐year‐old woman with a history of palpitations and documented long-RP supraventricular tachycardia (SVT). Topics include evaluating SVT mechanisms through VOP responses; distinguishing between atypical atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT); and challenges posed by inadvertent capture of the Purkinje conduction system during pacing.

Abstract In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled “SVT Quest” is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V‐A‐V or V‐A‐A‐V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His‐ventricular pathway‐related tachycardia based on observations such as V‐V‐A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure!

Background: Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar and bipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT. Methods: A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. Results: Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75). Conclusions: Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites. [ABSTRACT FROM AUTHOR]

Anatomic and electrophysiologic findings suggest that the actual circuit of atrioventricular nodal reentrant tachycardia (AVNRT) involves the perinodal atrium. However, occasional instances in which the atrium is dissociated from the AVNRT have led to the concept of an upper common pathway (UCP). We aimed to assess the prevalence of UCP in AVNRT using a late atrial premature depolarization (LAPD) maneuver. Patients who were diagnosed with typical AVNRT by electrophysiologic studies were enrolled. For evaluation of the presence of UCP, an LAPD was given at the coronary sinus ostium (osCS) during AVNRT, and then pacing was repeated incrementally every 10 ms. Electrograms in the earliest retrograde atrial activation site (ERAS) near the proximal His were mapped and recorded during the pacing. Results were interpreted as follows: absence of UCP—an LAPD from the osCS can reset the tachycardia without depolarizing the ERAS; presence of UCP—an LAPD from the osCS can depolarize the ERAS without resetting the tachycardia; and indeterminate—an LAPD from the osCS either resets the ERAS and tachycardia simultaneously or does not reset both. The LAPD maneuver was performed in 126 patients with AVNRT. It demonstrated an absence of UCP in 121 (96.0%) patients and the presence of UCP in 3 (2.4%) patients; the result was indeterminate in 2 (1.6%) patients. The LAPD maneuver revealed that the presence of UCP is indicated in only rare cases of AVNRT. In most AVNRT cases, the atrium is involved in the reentry circuit. [Display omitted] [ABSTRACT FROM AUTHOR]

In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled "SVT Quest" is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V‐A‐V or V‐A‐A‐V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His‐ventricular pathway‐related tachycardia based on observations such as V‐V‐A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure! [ABSTRACT FROM AUTHOR]

Abstract Background Atrioventricular nodal reentrant tachycardia (AVNRT) sometimes recurs even after anatomical slow pathway (SP) ablation targeting the rightward inferior extension (RIE). This multicenter study aimed to determine the reasons for AVNRT recurrence. Methods and Results Forty‐six patients were treated successfully for recurrent AVNRT. Initial treatment was for 38 slow‐fast AVNRTs, 3 fast‐slow AVNRTs, 2 slow‐slow AVNRTs, 2 slow‐fast and fast‐slow AVNRTs, and 1 noninducible AVNRT. All initial treatments were of RF application to the RIE; SP elimination was achieved in 11, dual AVN physiology was seen in 29, and AVNRT remained inducible in 5. The recurrent AVNRTs included 34 slow‐fast AVNRTs, 6 fast‐slow AVNRTs, 3 slow‐slow AVNRTs, 2 slow‐fast and fast‐slow AVNRTs, and 1 slow‐fast and slow‐slow AVNRTs. Successful ablation site was within the RIE in 39 and left inferior extension in 7. In 30 of 39, the successful RIE site was in the same area or higher than that of the initial procedure. Conclusion For a high majority (around 85%) of patients in whom AVNRT recurs after initial ablation success, the site of a second successful procedure will be within the RIE even though the RIE was originally targeted. Furthermore, a high majority (around 86%) of sites of successful ablation will be higher than those originally targeted.

The article presents a case study of a 21-year-old woman undergoing electrophysiological study for long RP (Refractory Period) tachycardia. It initially suspected atrial tachycardia or atypical atrioventricular nodal reentrant tachycardia (aAVNRT), later confirming slow-slow AVNRT. It is reported that Radiofrequency ablation targeted the AV (atrioventricular) node's right inferior extension, successfully resolving the tachycardia.

The article focuses on exploring the mechanism behind narrow QRS tachycardia recurrence in a patient years after undergoing "rightward inferior extension" ablation for atrioventricular nodal reentrant tachycardia (AVNRT). Topics include the identification of the tachycardia's origin near the His bundle, unsuccessful ventricular entrainment pacing, and the diagnostic challenges posed by variations in atrio-His intervals during electrophysiological study and ablation procedures.

Slow pathway elimination of the atrioventricular node (AVN) is essential to treat AVN reentrant tachycardia (AVNRT). However, injury to the AVN conduction (IAVN) is one of the serious complications. Cryofreezing energy is expected to reduce the incidence of IAVN. This study aimed to investigate the usefulness of a novel method to avoid IAVN during cryoablation of AVNRT. A total of 157 patients (average age, 65.8 years; male, 71) suffering from AVNRT were included. Once the AVNRT terminated during cryo-ablation, then rapid atrial constant pacing (RACP) was performed during freezing at a rate lower 10 bpm than that inducing Wenchebach AV block in 74 (47.1 %) patients (Group A). The RACP rate was decreasingly reduced by 10 bpm in case of the occurrence of IAVN. When the RACP reached 100 bpm, the cryoablation was prematurely terminated. Group B patients (83 = 52.9 %) underwent cryoablation during sinus rhythm. All patients were allocated in a randomized fashion. We compared the severity of the IAVN between Groups A and B. There were no significant differences at 12 months regarding the freedom from the AVNRT between Groups A and B. However, the duration of the IAVN was significantly longer in Group B than A (p = 0.02). There were no significant differences regarding the distance between the His recording sites and successful ablation sites between Groups A and B. No permanent IAVN requiring pacemaker implantation was provoked in either group. RACP was useful to avoid sustained and serious IAVN during cryoablation of AVNRT. [Display omitted] • The research of cryofreezing ablation system for atrioventricular nodal reentrant tachycardia. • Method to avoid serious atrioventricular conduction impairment. • The beneficial effects of rapid atrial pacing on atrioventricular nodal conduction during cryofreezing ablation. [ABSTRACT FROM AUTHOR]

Differentiating between atypical atrioventricular nodal reentrant tachycardia (AVNRT) and orthodromic reciprocating tachycardia utilizing a septal accessory pathway is a complex challenge. The purpose of this study was to describe the "local VA index," a straightforward method based on signals from the coronary sinus catheter, to distinguish between these arrhythmias during tachycardia and entrainment. The ventriculoatrial (VA) interval on the coronary sinus catheter is measured during tachycardia and entrainment, at the site of earliest atrial activity. The difference between these 2 situations defines the "local VA index." We also propose a mechanism to clarify the limitations of historical pacing maneuvers, such as postpacing interval minus tachycardia cycle length (PPI-TCL) and stimulus–atrial interval minus ventriculoatrial interval (SA-VA), by examining nodal decrement and intraventricular conduction delay. In a retrospective study of 75 patients referred for supraventricular tachycardia evaluation, 37 were diagnosed with atrioventricular reentrant tachycardia (AVRT) with orthodromic reciprocating tachycardia, and 38 with AVNRT (27 typical, 11 atypical). In comparison to AVRT patients, AVNRT patients exhibited longer PPI-TCL (176 ± 47 ms vs 113 ± 42 ms; P <.01) and SA-VA (138 ± 47 ms vs 64 ± 28 ms; P <.01). The AVRT group had mean local VA index of –1 ± 13 ms, whereas the AVNRT group had a significantly longer index of 91 ± 46 ms (P <.01). An optimal threshold for differentiation was a local VA index of 40 ms. Importantly, there was no significant correlation between pacing cycle length and nodal decrement as well as intraventricular delay related to pathway location. This interindividual variability might explain misleading interpretations of PPI-TCL and SA-VA. This novel approach is advantageous because of its simplicity and effectiveness, requiring only 2 diagnostic catheters. A local VA interval difference <40 ms provides a clear distinction for AVRT. [ABSTRACT FROM AUTHOR]

Background: We hypothesized that high-resolution activation mapping during sinus rhythm (SR) in Koch's triangle (KT) can be used to describe the most delayed atrial potential around the atrioventricular node and evaluated whether ablation targeting of this potential is safe and effective for the treatment of patients with typical atrioventricular nodal reentrant tachycardia (AVNRT). Methods: We conducted a prospective, non-randomized, observational study using high-resolution activation mapping from the sinus node to KT with a PENTARAY or OCTARAY catheter using the CARTO 3 cardiac mapping system (Biosense Webster) during SR in 62 consecutive patients (22 men; age [mean ± standard deviation] = 55 ± 14 years) treated for typical AVNRT at our institution from August 2021 to March 2023. Results: In all cases, the most delayed atrial potential was observed near the His potential within KT. Ablation targeting of this potential helped successfully treat each case of AVNRT, with a junctional rhythm observed at the ablation site. Initial ablation was deemed successful in 55/62 patients (89%); in the remaining seven patients, lesion expansion resolved AVNRT. One procedural complication occurred, namely, a transient atrioventricular block lasting 45 s. One patient experienced a transient tachycardic episode by the 1-month follow-up, but no further episodes were noted up to the 1-year follow-up. Conclusion: Activation mapping at KT during SR with the high-resolution CARTO system clearly revealed the most delayed atrial potential near the His potential within KT. Targeting this potential was a safe and effective treatment method for patients with typical AVNRT in our study. [ABSTRACT FROM AUTHOR]

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.

Abstract Background This study aimed to establish a systematic method for diagnosing atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed nodoventricular pathway (cNVP). Methods We analyzed 13 cases of AVNRT with a bystander cNVP, 11 connected to the slow pathway (cNVP‐SP) and two to the fast pathway (cNVP‐FP), along with two cases of cNVP‐related orthodromic reciprocating tachycardia (ORT). Results The diagnostic process was summarized in three steps. Step 1 was identification of the presence of an accessory pathway by resetting the tachycardia with delay (n = 9) and termination without atrial capture (n = 4) immediately after delivery of a His‐refractory premature ventricular contraction (PVC). Step 2 was exclusion of ORT by atrio‐His block during the tachycardia (n = 4), disappearance of the reset phenomenon after the early PVC (n = 7), or dissociation of His from the tachycardia during ventricular overdrive pacing (n = 1). Moreover, tachycardia reset/termination without the atrial capture (n = 2/2) 1 cycle after the His‐refractory PVC was specifically diagnostic. Exceptionally, the disappearance of the reset phenomenon was also observed in the two cNVP‐ORTs. Step 3 was verification of the AVN as the cNVP insertion site, evidenced by an atrial reset/block preceding the His reset/block in fast–slow AVNRT with a cNVP‐SP and slow–fast AVNRT with a cNVP‐FP or His reset preceding the atrial reset in slow–fast AVNRT with a cNVP‐SP. Conclusion AVNRT with a bystander cNVP can be diagnosed in the three steps with few exceptions. Notably, tachycardia reset/termination without atrial capture one cycle after delivery of a His‐refractory PVC is specifically diagnostic.

Introduction: The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. Methods and Results: In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior‐to‐inferior (SPSI), anterior‐to‐posterior (SPAP), and right‐to‐left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior‐to‐inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7 ± 6.4, 1.7 ± 6.4, 13.6 ± 12.3, and −1.0 ± 13.0 mm, respectively. The HISSI was positively correlated with SPSI (R2 = 0.62; P <.01) and SPAP (R2 = 0.22; P <.01), whereas it was not correlated with SPRL (R2 = 0.01; P =.65). The distance between the HIS and SP ablation site was 17.7 ± 6.4 mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI ≥ 13 mm) and low HIS group (HISSI < 13 mm) (0.10 ± 0.06 vs. 0.10 ± 0.06; P =.38). Conclusion: In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases. [ABSTRACT FROM AUTHOR]

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia, and its diagnostic and therapeutic approaches have been well-established. Traditionally, AVNRT is understood to be an intranodal reentry having two bystander pathways; the upper common pathway (UCP) which connects to the atrium and the lower common pathway which connects to the ventricle. However, the existence of the UCP remains a subject of ongoing debate. The assertion of the UCP’s presence is supported by electrophysiological evidence suggesting that the atrium is not essential for the perpetuation of AVNRT. Nonetheless, numerous anatomical studies have failed to identify any structure that could be conclusively designated as the UCP. The histological and electrophysiological characteristics of the slow and fast pathways, which are the core components of AVNRT, suggest the inclusion of atrial myocardium in the reentry circuit. While clear interpretation of these discrepancies remains elusive, potential explanations may be derived from existing evidence and recent research findings concerning the actual AVNRT circuit. [ABSTRACT FROM AUTHOR]

Background: This study aimed to establish a systematic method for diagnosing atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed nodoventricular pathway (cNVP). Methods: We analyzed 13 cases of AVNRT with a bystander cNVP, 11 connected to the slow pathway (cNVP‐SP) and two to the fast pathway (cNVP‐FP), along with two cases of cNVP‐related orthodromic reciprocating tachycardia (ORT). Results: The diagnostic process was summarized in three steps. Step 1 was identification of the presence of an accessory pathway by resetting the tachycardia with delay (n = 9) and termination without atrial capture (n = 4) immediately after delivery of a His‐refractory premature ventricular contraction (PVC). Step 2 was exclusion of ORT by atrio‐His block during the tachycardia (n = 4), disappearance of the reset phenomenon after the early PVC (n = 7), or dissociation of His from the tachycardia during ventricular overdrive pacing (n = 1). Moreover, tachycardia reset/termination without the atrial capture (n = 2/2) 1 cycle after the His‐refractory PVC was specifically diagnostic. Exceptionally, the disappearance of the reset phenomenon was also observed in the two cNVP‐ORTs. Step 3 was verification of the AVN as the cNVP insertion site, evidenced by an atrial reset/block preceding the His reset/block in fast–slow AVNRT with a cNVP‐SP and slow–fast AVNRT with a cNVP‐FP or His reset preceding the atrial reset in slow–fast AVNRT with a cNVP‐SP. Conclusion: AVNRT with a bystander cNVP can be diagnosed in the three steps with few exceptions. Notably, tachycardia reset/termination without atrial capture one cycle after delivery of a His‐refractory PVC is specifically diagnostic. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 44-year-old female patient who underwent catheter ablation therapy for a slightly irregular supraventricular tachycardia (SVT). It also discusses the mechanisms of ventriculoatrial (VA) block during SVT, the differential diagnosis involving various types of tachycardias, and the role of upper common pathway (UCP) in AVNRT.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) does not commonly present during infancy. Although relative safety of catheter ablation of AVNRT has been demonstrated in pediatrics, this procedure is rarely indicated in children <15 kg. Methods: Retrospective review of seven cases of AVNRT that presented in children younger than 1 year of age and required catheter ablation for definitive management. Electrophysiology (EP) study was planned with two or three catheters. Area of ablation determined by voltage mapping, propagation sinus wave collision and slow pathway potential location. Ablation performed with cryothermal energy. No fluoroscopy was used. Results: Presentation ranged from 36 weeks of gestation to 11 months of age. Two presented in fetal life and two in the neonatal period. The median age of ablation was 20 months (range 17–31 months). The median weight at ablation was 11.4 kg (range 8.9–14.9 kg). Median follow‐up time was 16 months. All had typical AVNRT. The median tachycardia cycle length was 216 ms. 100% successful rate using cryoablation. No complications. No recurrence of tachycardia during the follow‐up period. Conclusion: Slow AV nodal pathway cryoablation may be safely performed, with good short and medium‐term outcomes in patients under 15 kg. [ABSTRACT FROM AUTHOR]

Ultra-high-density mapping was used for potential-guided radiofrequency ablation for typical atrioventricular nodal reentrant tachycardia. The mapping detailed the spread of activation in the Koch’s triangle and identified target potentials and tachycardia circuits. This mapping provides additional information to the slow pathway conventionally used for safe and effective ablation. [ABSTRACT FROM AUTHOR]

A 54-year-old male without medical history presented to our emergency department with sudden chest pain and palpitations. Electrocardiogram showed wide QRS tachycardia similar to left bundle branch block. Electrophysiological study showed fast/slow type atrioventricular nodal reentrant tachycardia and revealed transient HV block during tachycardia. [ABSTRACT FROM AUTHOR]

Background: The identification of a "low-voltage bridge" to guide ablation of atrioventricular nodal reentry tachycardia (AVNRT) has been described as a safe and effective strategy in children. We investigated the presence of a low-voltage bridge in adult patients undergoing AVNRT ablation, to evaluate its anatomical correspondence with the successful ablation site. We also investigated the possible correlations between Koch's triangle anatomy and patients' biometric characteristics. Methods: This observational registry prospectively collected data from 200 patients undergoing AVNRT ablation, guided by 3D electroanatomical mapping system, in 6 electrophysiology centers. Koch's triangle voltage map was collected; then, the anatomical correspondence between the low-voltage bridge and the successful ablation site was evaluated. Koch's triangle anatomical dimensions were subsequently drawn from the mapping system and correlated to patients' gender, age, and weight. Results: The low-voltage bridge was identified in 159 over 200 procedures (79.5%). When the low-voltage bridge was identified, its anatomical correspondence with the successful ablation site has been proved in 137 over 159 cases (86%), with a reduction of radiofrequency deployment time. No strict correlations were found, on the other side, between Koch's triangle anatomy and patients' biometric data. Conclusions: The identification of the low-voltage bridge has proved to be a helpful strategy to guide AVNRT ablation in a large cohort of adult patients. Targeting the low-voltage bridge during AVNRT ablation helps to reduce RF application time. Koch's triangle morphological characteristics cannot be predicted on the base of patients' biometric data. [ABSTRACT FROM AUTHOR]

The optimal strategy for electroanatomic mapping-guided cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) remains unclear. The purpose of this study was to investigate the effectiveness of slow pathway late activation mapping (SPLAM) and voltage gradient mapping for AVNRT cryoablation. From June 2020 to February 2022, all consecutive patients with AVNRT underwent SPLAM to define the wave collision point and voltage gradient mapping to define the low-voltage bridge (LVB). Conventional procedures performed from August 2018 to May 2020 served as control. The study and control groups comprised 36 patients (age 16.5 ± 8.2 years) and 37 patients (age 15.5 ± 7.3 years), respectively. Total procedural times were comparable, and acute success rates were 100% in both groups. Compared to controls, the number of cryomapping attempts (median 3 vs 5; P =.012) and cryoablation applications (median 1 vs 2; P <.001) were significantly lower in the study group. At median follow-up of 14.6 and 18.3 months, recurrence rates were 5.6% (2 patients) and 10.8% (4 patients) in the study and control groups (P =.402), respectively. Mapping of the Koch triangle took 11.8 ± 3.6 minutes, during which 1562 ± 581 points were collected. In SPLAM, wave collision points were defined and compatible with the final successful lesion sites in all patients, including those with multiple slow pathways. LVB could not be defined in 6 patients (16.7%), and LVB was not compatible with the final successful lesion in another 6 (16.7%). For AVNRT cryoablation, SPLAM could effectively guide the localization of slow pathway ablation sites and was particularly beneficial in patients with multiple slow pathways. [ABSTRACT FROM AUTHOR]

Slow pathway (SP) mapping and modification can be challenging in patients with persistent left superior vena cava (PLSVC) due to anatomic variance of the Koch triangle (KT) and coronary sinus (CS) dilation. Studies using detailed 3-dimensional (3D) electroanatomic mapping (EAM) to investigate conduction characteristics and guide ablation targets in this condition are lacking. The purpose of this study was to describe a novel technique of SP mapping and ablation in sinus rhythm using 3D EAM in patients with PLSVC after validation in a cohort with normal CS anatomy. Seven patients with PLSVC and dual atrioventricular (AV) nodal physiology who underwent SP modification with the use of 3D EAM were included. Twenty-one normal heart patients with AV nodal reentrant tachycardias formed the validation group. High-resolution, ultra-high-density local activation timing mapping of the right atrial septum and proximal CS in sinus rhythm was performed. SP ablation targets were consistently identified by an area in the right atrial septum with the latest activation time and multicomponent atrial electrogram adjacent to a region with isochronal crowding (deceleration zone). In PLSVC patients, these targets were located at or within 1 cm of the midanterior CS ostium. Ablation in this area led to successful SP modification, reaching standard clinical endpoints with a median of 43 seconds of radiofrequency energy or 14 minutes of cryoablation without complications. High-resolution activation mapping of the KT in sinus rhythm can facilitate localization and safe SP ablation in patients with PLSVC [Display omitted] [ABSTRACT FROM AUTHOR]

The article presents a case of a 60-year-old woman with recurrent narrow QRS tachycardia and a structurally normal heart. Through an electrophysiology study, the authors diagnose the patient with both typical atrioventricular nodal reentrant tachycardia (AVNRT) and atrial tachycardia, highlighting the challenges in identifying and treating dual tachycardias.

Models are proposed to describe the heart’s action potential. A system of stochastic differential equations is used to recreate pathological behaviour in the heart such as atrioventricular nodal reentrant tachycardia (AVNRT) and also AVNRT with conduction aberration. Part of the population has abnormal accessory pathways: fast and slow. An additional pathway is not always induced, since the deterministic model is not proper due to a stochasticity in this process. Introduction of a stochastic term allows modelling a pre-excitation perturbation (such as unexpected excitation by premature contractions in atrium (PAC)) which triggers the mechanism of AVNRT. Also, a system of AVNRT with additional conduction aberration, which is a rare type of arrhythmia, is considered. The aim of this work is to propose a mathematical model superior to the deterministic one that recreates this disease better and allows understanding its mechanism and physical dependencies, which may help to propose a new therapy of AVNRT. Results are illustrated with numerical solutions.

Abstract Background The coexistence of clinical atrioventricular nodal reentrant tachycardia (AVNRT) and drug‐induced type 1 Brugada pattern (DI‐Type 1 BrP) has been previously reported. The present study was designed to determine the 12‐lead ECG characteristics at baseline and during AVNRT and to identify a subset of 12‐lead ECG variables of benefit associated with underlying Brugada syndrome (BrS)/DI‐Type 1 BrP among patients with slow/fast AVNRT. Methods A total of 40 (11 numerical/29 categorical) 12‐lead ECG parameters were analyzed and compared between patients with (n = 69) and without (n = 104) BrS/DI‐Type1‐BrP matched for age, female gender, body mass index, left ventricular ejection fraction and comorbid conditions. Five distinct types of ECG pattern (Type A/B/C/D/E) in V1–V2 leads during AVNRT were defined. Results A total of nine electrocardiographic variables, four at baseline, and five during AVNRT were identified. At baseline, patients with BrS/DI‐Type 1 BrP had higher prevalence of interatrial block, leftward shift of frontal plane QRS axis, the absence of normal QRS pattern (the presence of rSr’ pattern or type 2/3 Brugada pattern) in V1–V2 and QRS fragmentation in inferior leads compared to patients without BrS/DI‐Type 1 BrP. During AVNRT, patients with BrS/DI‐Type 1 BrP had higher prevalence of Type A ECG pattern (“coved‐type” ST‐segment elevation) in V1–V2, Type C ECG pattern (pseudo‐r’ deflection in V1 and “RBBB‐like” pattern in V2), pseudo‐r’ deflection in V1, QRS fragmentation in inferior leads and “isolated” QRS fragmentation/notching/slurring in aVL compared to patients without BrS/DI‐Type 1 BrP. Conclusions We identify several electrocardiographic variables that point to an underlying type 1 BrP among patients with slow/fast AVNRT.

Palpitations in the elderly are mostly of cardiac origin. Atrial fibrillation is the most common arrhythmia in the elderly, whereas paroxysmal supraventricular tachyarrhythmias are uncommon. Here, we describe the case of an elderly woman who presented with paroxysms of palpitations of 15-year duration and who had been undiagnosed till presenting to our geriatric service. The patient was diagnosed to have a slow–fast type (typical) atrioventricular nodal reentrant tachycardia which was successfully managed with ablation of the slow pathway. The long symptomatic period when the patient remained undiagnosed due to neglect is a notable feature of our case. The case also highlights the unified protocol for the management of narrow complex regular tachyarrhythmias and the definitive role of ablation even in elderly patients.

Introduction: Radiofrequency ablation (RFA) slow pathway modification for catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed using a 4‐mm nonirrigated (NI) RF ablation catheter. Slow pathway modification using irrigated, contact‐force sensing (ICFS) RFA catheters has been described in case reports, but the outcomes have not been systematically evaluated. Methods: Acute procedural outcomes of 200 consecutive patients undergoing slow pathway modification for AVNRT were analyzed. A 3.5‐mm ICFS RFA catheter (ThermoCool SmartTouch STSF, Biosense Webster, Inc.) was utilized in 134 patients, and a 4‐mm NI RFA catheter (EZ Steer, Biosense Webster, Inc.) was utilized in 66 patients. Electroanatomic maps were retrospectively analyzed in a blinded fashion to determine the proximity of ablation lesions to the His region. Results: The baseline characteristics of patients in both groups were similar. Total RF time was significantly lower in the ICFS group compared to the NI group (5.53 ± 4.6 vs. 6.24 ± 4.9 min, p = 0.03). Median procedure time was similar in both groups (ICFS, 108.0 (87.5–131.5) min vs. NI, 100.0 (85.0–125.0) min; p = 0.2). Ablation was required in closer proximity to the His region in the NI group compared to the ICFS group (14.4 ± 5.9 vs. 16.7 ± 6.4 mm, respectively, p = 0.01). AVNRT was rendered noninducible in all patients, and there was no arrhythmia recurrence during follow‐up in both groups. Catheter ablation was complicated by AV block in one patient in the NI group. Conclusion: Slow pathway modification for catheter ablation of AVNRT using an ICFS RFA catheter is feasible, safe, and may facilitate shorter duration ablation while avoiding ablation in close proximity to the His region. [ABSTRACT FROM AUTHOR]