Search

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.

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.

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 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.

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).

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]

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]

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.

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: 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]

Introduction: Either cryoenergy or radiofrequency can be used during atrioventricular nodal reentrant tachycardia (AVNRT) ablation. There are still limited data comparing their respective long‐term efficacy (>1 year). This study sought to compare the very long‐term outcomes of AVNRT ablation using radiofrequency or cryotherapy. Methods: We retrospectively included all patients who had undergone a first AVNRT ablation in our institution between January 2010 and December 2017. The primary endpoint was recurrence of documented AVNRT. Results: The study population consisted of 409 patients (274 females; mean age, 49.9 years). Ablation was performed using cryoenergy in 260 patients and radiofrequency in 149. High acute procedural success rate (>98%) was obtained and no permanent AV block was observed using both techniques. During a mean follow‐up of 3.3 ± 2.3 years, documented AVNRT recurrence occurred in 24 (9.2%) and 4 patients (2.7%) in the cryoablation (CA) and radiofrequency (RF) group, respectively. The risk of AVNRT recurrence was significantly higher in the CA group as compared with the RF group (hazard ratio [HR] = 3.7; 95% confidence interval [CI], 1.3–5.9). Most of the recurrences after CA occurred between 1‐ and 6‐year follow‐up (14/24; 58.3%), with one‐third of late recurrences after 3‐year follow‐up. In multivariable analysis, only Koch's triangle anatomical variant was associated with AVNRT recurrence after CA (HR = 6.7; 95% CI, 2.7–16.3). Conclusion: While AVNRT recurrence rates were similar at 1 year of follow‐up regardless of the energy used, long‐term efficacy appeared higher after radiofrequency ablation. Strikingly, recurrences occured much later after cryotherapy compared with radiofrequency ablation. [ABSTRACT FROM AUTHOR]

The classical form of typical atrioventricular node reentrant tachycardia (AVNRT) is a "slow‐fast" pathways tachycardia, and the usual therapy is an ablation of the slow pathway since it carries a low risk of atrioventricular (AV) block. In patients with long PR interval and/or living on the anterograde slow pathway, an alternative technique is required. We report a case of a 42‐year‐old lady with idiopathic restrictive cardiomyopathy, persistent atrial fibrillation status post pulmonary vein isolation, and premature ventricular complex ablation with a systolic dysfunction, who presented with incessant slow narrow complex tachycardia of 110 bpm that appeared to be an AVNRT. Her baseline EKG revealed a first‐degree AV block with a PR of 320 ms. EP study showed no evidence of anterograde fast pathway conduction. Given this fact, the decision was to attempt an ablation of the retrograde fast pathway. The fast pathway was mapped during tachycardia to its usual location into the anteroseptal region, then radiofrequency ablation in this location terminated tachycardia. After ablation, she continued to have her usual anterograde conduction through slow pathway and the tachycardia became uninducible. In special populations with prolonged PR interval or poor anterograde fast pathway conduction, fast pathway ablation is the required ablation for typical AVNRT. [ABSTRACT FROM AUTHOR]

The article presents a case study related to 57-year-old lady presented with history of very frequent and recurrent episodes of palpitation lasting many hours despite being on high dose of diltiazem. Topics include the synchronous premature ventricular contraction (PVC) has delivered from the right ventricular (RV) apex during tachycardia, and the response to another His-synchronous PVC delivered from RV base.

The article describes the case of a 57-year-old man who developed ventricular tachycardia (VT) inducing typical atrioventricular-nodal reentrant tachycardia (AVNRT) with severe hypotension and persisting after termination of the VT. The patient was presented with an old anterior wall myocardial infarction and left ventricular ejection fraction of 0.3 and developed episodes of paroxysmal palpitations. Holter monitoring showed four salvos of short-lived broad QRS tachycardia.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping‐system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow‐pathway identification, and ablation become increasingly important. We present a novel method of slow‐pathway identification and initial ablation results from this method. Methods and Results: We examined AVNRT ablations performed at our institution over a 12‐month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow‐up (median, day 51), one patient had lower‐extremity deep‐vein thrombosis and pulmonary embolus, and one had a lower‐extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation. Conclusions: Mapping‐system detection of late‐activation, low‐amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 65-year-old female patient presented with recurrent episodes of symptomatic tachycardia and a baseline electrocardiogram did not show pre-excitation. Topics include the electrocardiogram of the event recorder during tachycardia exhibited a narrowQRS complex, the patient's tachycardia was resistant to medication, and the electrophysiological study was performed after obtaining written informed consent.

The article presents a case of a 38-year-old man who was presented to a center due to recurrent paroxysmal supraventricular tachycardia to discuss the mechanism of transient aberrancy during atrioventricular nodal reentrant tachycardia (AVNRT). Other topics include how tachycardia cycle lenth variation was dependent on AH interval changes, and the mechanisms of the observed right bundle branch block (RBBB) during ventricular resetting maneuver.

A case study of a 76‐year‐old patient diagnosed with symptomatic tachycardia, is presented. Topics discussed include physical and echocardiographic examination showed no abnormalities; initiation is by a single supraventricular premature beat.1 Initiation of AV nodal re‐entrant tachycardia (AVNRT) during sinus rhythm; and refractory from the impulse coming down anterogradely during sinus rhythm.

The atrioventricular (AV) node generates half of the AV delay needed for blood pumping and filters atrial impulses that could otherwise induce life‐threatening ventricular arrhythmias. It is also a pacemaker and a key target in the treatment of cardiac arrhythmias. The special roles of the AV node primarily arise from its slow conduction, long refractory period, and cellular automaticity. However, efforts to establish the dynamics of these properties and their interaction led to many controversies. In fact, the AV node's behavior is so complex that it seems to escape broadly applicable rules. This review summarizes progresses made in resolving these issues and in integrating the multiple roles of the AV node within a common functional model. Presented evidence shows that the rate‐dependent conduction and refractory properties of the AV node can be reliably characterized and reconciled from nodal responses to S1S2S3 protocols. It also supports the concept that dual pathways constitute a feature of the normal AV node and account for its overall conduction and refractory properties. In this model, the posterior extension and compact node provide the core of the slow and fast pathway, respectively. The transitional tissues and lower nodal bundle provide a common proximal and distal pathway, respectively. These pathways would also support bidirectional conduction. The dual pathway involvement can also be extended to widely variable AV nodal responses, such as Wenckebach cycles, hysteresis, and ventricular response to atrial fibrillation. In brief, the intricate AV nodal behavior may obey a limited set of accessible and definable rules. [ABSTRACT FROM AUTHOR]

The article present a case study of a 33-year old woman with regular palpitations and documented a shortRP narrowQRS complex tachycardia. Topics discussed include the retrograde conduction was decremental and concentric with the earliest activation site at the His bundle region; the presence of anterograde dual AV nodal pathways; and origin of atrial tachycardia (AT) from near the AV node.

A 32‐year‐old woman underwent radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine. [ABSTRACT FROM AUTHOR]

The article describes the case of a 40-year-old female diagnosed with dual tachycardia with 1:2 tachycardia and atrioventricular (AV) nodal reentrant tachycardia with retrograde 1:2 response. Topics include twelve-lead electrocardiogram during sinus rhythm, the possibility of dual AV nodal pathways with simultaneous fast and slow conduction, and the relationship between the His potentials of the fast and slow pathways.

The article presents a case study of a 20-year-old woman who was referred to radiofrequency catheter ablation of narrow QRS tachycardia for incomplete right bundle branch block (RBBB) morphology. It discusses the diagnosis of changes in QRS morphology with shortening of hisio-ventricular interval after electrophysiology study along with ventricular overdrive pacing (VOD).

The article presents a case study of A70-year-oldmanwith a history of complete AVblock status post dual chamber permanent pacemaker implantation presented to the emergency department complaining of worsening fatigue and palpitations. The recording of Electrocardiography was interpreted as atrial tachycardia; pacemaker-mediated tachycardia; or atrioventricular nodal reentrant tachycardia. Tachycardia was terminated with an incidental ventricular pacing from pacemaker.

Abstract: Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common tachyarrhythmia substrate in children, which is successfully treated by catheter ablation using radiofrequency or cryothermal energy. In recent years, cryoablation (Cryo) using electroanatomical system guidance is more commonly preferred for use in children in order to decrease the risk of an atrioventricular block. However, there are concerns regarding the long‐term efficacy of Cryo in treating AVNRT. We aimed to evaluate the feasibility, safety, and long‐term efficacy of Cryo for AVNRT in children. Methods and results: A total of 275 consecutive children above 4 years of age diagnosed with AVNRT were included in our study. The EnSite system (St. Jude Medical, Inc., St. Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The study included 275 patients (148 females, age: 11.9 ± 3.6 years) undergoing catheter ablation for AVNRT from July 2012 to September 2016. Acute success was obtained in all (100%) patients with a mean procedure time of 140 ± 44 minutes. Fluoroscopy was used in only 12 (4.4%) patients. During a follow‐up time of 25.6 ± 13.5 months (median: 23 months), AVNRT recurred in 12 of 279 (4.4%) of the patients. Age, sex, number of Cryo lesions, and catheter tip size (6‐mm vs 8‐mm) were not predictive for recurrence. In nine patients, a repeat ablation was successfully performed with cryoenergy. Conclusions: Cryo for AVNRT is a safe and effective procedure with excellent long‐term outcomes. The use of electroanatomical systems during ablation significantly decreases exposure to fluoroscopy without compromising success. [ABSTRACT FROM AUTHOR]

Abstract: Background: Ablation is an effective treatment for atrioventricular nodal reentrant tachycardia (AVNRT). The occurrence of junctional ectopic rhythm (JER), including junctional ectopic tachycardia, following AVNRT ablation has been described as an extremely rare phenomenon, but may be underestimated. We aimed to determine the incidence of JER following AVNRT ablation within our institution, as well as that reported in the literature via an extensive review. Methods: We reviewed our adult ablation institutional experience for the occurrence of JER after AVNRT ablation from 2009 to 2016. Additionally, we conducted an extensive literature search using different databases looking for AVNRT ablation case series. The individually reported complications of these studies were reviewed, with a primary endpoint defined as the occurrence of JER shortly after AVNRT ablation. The study was approved by our institutional review board. Results: Our institutional data revealed 6/126 patients (prevalence 4.8%) developed non‐preexisting JER post‐AVNRT ablation. Four patients were asymptomatic. Two patients had persistent symptoms lasting over a year, with one patient requiring repeat ablation. The literature review included 149 adult and pediatric studies. There were three cases of reported JER, out of a total of 37,541 patients (31,768 adults and 5,773 pediatric; prevalence 0.008%). The three JER patients were pediatric, and all required further therapeutic intervention. Conclusion: JER might be an underreported complication of AVNRT ablation. It seems most often to be transient and self‐limited, occurring days to weeks after ablation, but may also be debilitating, requiring more aggressive management. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Stochastic damage of the ionizing radiation to both patients and medical staff is a drawback of fluoroscopic guidance during catheter ablation of cardiac arrhythmias. Therefore, emerging zero‐fluoroscopy catheter‐guidance techniques are of great interest. Methods and results: We investigated, in a prospective pilot study, the feasibility and safety of the cryothermal (CA) slow‐pathway ablation in patients with symptomatic atrioventricular‐nodal‐re‐entry‐tachycardia (AVNRT) using solely intracardiac echocardiography (ICE) for endovascular and endocardial catheter visualization. Twenty‐five consecutive patients (mean age 55.6 ± 12.0 years, 17 female) with ECG‐documentation or symptoms suggesting AVNRT underwent an electrophysiology study (EPS) in our laboratory utilizing ICE for catheter navigation. Supraventricular tachycardia was inducible in 23 (92%) patients; AVNRT was confirmed by appropriate stimulation maneuvers in 20 (80%) patients. All EPS in the AVNRT subgroup could be accomplished without need for fluoroscopy, relying solely on ICE‐guidance. CA guided by anatomical location and slow‐pathway potentials was successful in all patients, median cryo‐mappings = 6 (IQR:3–10), median cryo‐ablations = 2 (IQR:1–3). Fluoroscopy was used to facilitate the trans‐septal puncture and localization of the ablation substrate in the remaining 3 patients (one focal atrial tachycardia and two atrioventricular‐re‐entry‐tachycardias). Mean EPS duration in the AVNRT subgroup was 99.8 ± 39.6 minutes, ICE guided catheter placement 11.9 ± 5.8 minutes, time needed for diagnostic evaluation 27.1 ± 10.8 minutes, and cryo‐application duration 26.3 ± 30.8 minutes. Conclusions: ICE‐guided zero‐fluoroscopy CA in AVNRT patients is feasible and safe. Real‐time visualization of the true endovascular borders and cardiac structures allow for safe catheter navigation during the ICE‐guided EPS and might be an alternative to visualization technologies using geometry reconstructions. [ABSTRACT FROM AUTHOR]

Background There are limited adult data suggesting the tachycardia cycle length (TCL) of atrioventricular reentry tachycardia (AVRT) is shorter than atrioventricular nodal reentry tachycardia (AVNRT), though little data exist in children. We sought to determine if there is a difference in TCL between AVRT and AVNRT in children. Methods A single-center retrospective review of children with supraventricular tachycardia (SVT) from 2000 to 2015 was performed. Inclusion criteria: Age ≤ 18 years, invasive electrophysiology study (EPS) confirming AVRT or AVNRT. Exclusion criteria: Atypical AVNRT, congenital heart disease, antiarrhythmic medication use at time of EPS. Data were compared between patients with AVRT and AVNRT via t-test, χ2 test, and linear regression. Results A total of 835 patients were included (12 ± 4 years, 52 ± 31 kg, TCL 321 ± 55 ms), 539 (65%) with AVRT (270 Wolff-Parkinson-White, 269 concealed pathways) and 296 (35%) with AVNRT. Patients with AVRT were younger (11.7 ± 4.1 years vs 13.0 ± 3.6 years, P < 0.001) and smaller (49 ± 22 kg vs 57 ± 43 kg, P < 0.001). In the baseline state, the TCL was shorter in AVRT than AVRNT (329 ± 51 ms vs 340 ± 60 ms, P = 0.04). In patients requiring isoproterenol to induce SVT, there was no difference in TCL (290 ± 49 ms vs 297 ± 49 ms, P = 0.26). When controlling for age, there was no difference in TCL between AVRT and AVNRT at baseline or on isoproterenol. The regression equation for TCL in the baseline state was TCL = 290 + 4 (age), indicating the TCL will increase by 4 ms above a baseline of 290 ms for each year of life. Conclusions When controlling for age, there is no difference in the TCL between AVRT and AVNRT in children. Age, not tachycardia mechanism, is the most significant factor in predicting TCL. [ABSTRACT FROM AUTHOR]

Background We aimed to analyze the results of retrograde aortic radiofrequency catheter ablation of left-sided accessory pathways in children. Methods Between January 2010 and September 2014, 25 children who underwent left-sided accessory pathway ablation with a retrograde aortic approach were evaluated retrospectively. Results The mean age of the patients was 11.09±3.71 years. Seventeen patients were male (68%). The mean procedure and fluoroscopy times were 71.54±21.05 min and 31.42±19.57 min, respectively. Radiofrequency energy was delivered with 41.38±15.32 W at 52.38±5.45 °C. Sixteen patients (64%) presented with manifest preexcitation and, 9 had concealed accessory pathways. The location of accessory pathway was left lateral in 16 patients, posteroseptal in 5, left anterolateral in 2, and left posterolateral and left posterior in the remaining 2. The acute success rate was 96%. The patients were followed for a mean of 16.68±18.01 months. There were 2 recurrences. No major complications were observed in the periprocedural period. One patient had groin hematoma, another one had transient severe headache and vomiting. Trivial mitral regurgitation was noted in a patient, which remained the same throughout follow-up. None of the patients developed new aortic regurgitation, pericardial effusion, or thrombi at the site of ablation. Conclusions The retrograde aortic approach can be safely employed with a high success rate for ablation of left-sided accessory pathways in children. [ABSTRACT FROM AUTHOR]

A 66-year-old woman with palpitations was referred to our center for catheter ablation due to drug-refractory, common type atrioventricular nodal tachycardia (AVNRT). A selective slow pathway ablation was attempted. A fast junctional rhythm with transient ventriculoatrial block followed by transient prolongation of the A–H interval occurred immediately after the radiofrequency (RF) application at the coronary sinus ostium (CSOS) level. To assess the location of the fast pathway and His bundle, we sought to visualize the anatomy of the triangle of Koch (TOK) by three-dimensional computed tomography (CT). [ABSTRACT FROM AUTHOR]

The article presents a case study of a 44-year-old woman with idiopathic dilated cardiomyopathy who have rescued by dual-chamber Boston Scientific Teligen 100 implantable cardioverter defibrillator (ICD). Topics discussed include electrophysiological study with induction of atrioventricular nodal reentrant tachycardia (AVNRT); continuous rhythm monitoring; and using device tracings and application of principles making successful rescuing.

'2 for 1 phenomenon' is simultaneous anterograde conduction over the fast and slow pathways of the atrioventricular (AV) nodal pathway, leading to a double ventricular response from each atrial beat. This phenomenon can initiate AV nodal reentrant tachycardia (AVNRT). The unique induction of AVNRT was observed in a patient with an implantable cardioverter defibrillator in our case. Minimal to no retrograde invasion of the slow pathway from the anterogradely conducted fast pathway depolarization is the most accepted explanation. [ABSTRACT FROM AUTHOR]

Background The incidence and electrocardiographic characteristics of atrial tachycardia (AT) among long RP tachycardias have not been fully elucidated. Methods and results Thirty-six patients with 37 long RP tachycardias were classified as having AT ( n =23) or non-AT ( n =14). We analyzed the electrocardiographic features, including the ratio between the RP and PR intervals (RP/PR ratio), P-wave morphology, and P-wave duration. The RP/PR ratio was higher in AT than in non-AT (2.01±0.54 vs. 1.57±0.24, P <0.001). A negative P wave in the inferior leads was less common in AT (4/23 vs. 13/14, P <0.01). The P-wave duration was longer in AT than in non-AT (105±13 ms vs. 84±10 ms, P <0.001). The fulfillment of any 2 of the following had a specificity and a positive predictive value of 100% for AT: RP/PR ratio of ≥1.65, absence of negative P wave in the inferior leads, or a P-wave duration of >96 ms. Conclusion AT accounted for nearly two thirds of long RP tachycardias in this cohort. Electrocardiographic features, including the RP/PR ratio, polarity of the P wave, and P-wave duration were useful in the differentiation of AT. [ABSTRACT FROM AUTHOR]

Introduction: Mapping of the antegrade fast pathway (A-FP) exact sites and antegrade slow pathway (A-SP) input locations has not been well described. Methods: In 56 patients with slow-fast atrioventricular nodal reentrant tachycardia (SF-AVNRT), pacing during sinus rhythm and entrainment pacing during SF-AVNRT were performed at various sites in the triangle of Koch and coronary sinus (CS) to identify the A-FP and A-SP inputs. User-defined threedimensional electro-anatomical mapping of the stimulus-His potential (St-H) interval and anatomical location was performed. The A-FP input was defined as the site of the shortest St-H interval, and A-SP input as the site of the shortest St-H interval and with a postpacing-interval equal to the tachycardia cycle length. The locations of the A-FP and A-SP inputs were mapped as a ratio of the distance between the His bundle (HB) and CS orifice (CSO), and the HB-CSO axis was divided into three zones: superior-, mid-, and inferior septum. The distance between the A-SP and A-FP inputs was calculated using the distance from each input to the HB and HB-CSO axis. Results: Only 30 patients were included in this study because the A-SP mapping failed in 26. The A-SP input was distributed to the superior septum in four, mid- or inferior septum in 25, and CS in one. An A-SP input which was located less than 10 mm from the A-FP input was observed in one of four patients with a superior septum A-SP. Conclusions: An A-SP input at the superior septum seemed to be a potential risk for atrioventricular nodal injury during ablation. [ABSTRACT FROM AUTHOR]

Meta-Analysis of Cryoablation for AVNRT Introduction Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. High success rates have been accompanied with a small risk of atrioventricular (AV) block. Cryoablation has been used as an alternative to radiofrequency (RF) ablation, but studies have been underpowered in comparing the 2 techniques. Methods and Results An electronic search and hand-search of reference lists for published and unpublished data was carried out. Comparative studies (cohort and randomized controlled trials) of RF versus cryoablation for AVNRT were identified independently by 2 reviewers. Searches were limited to English language human studies. The primary metameter was long-term AVNRT recurrence (>2 months postprocedure and ECG/electrophysiology study [EPS]-documented) and secondary metameters included acute procedural failure and AV block requiring pacing. A total of 5,617 patients in 14 trials were included in this systematic review. Acute procedural failure with cryoablation was slightly higher than with RF ablation, but the difference was not statistically significant (risk ratio [RR] 1.44 [95% confidence interval; CI 0.91-2.28], P = 0.12). Long-term recurrence was higher with cryoablation (RR 3.66 [95% CI 1.84-7.28], P = 0.0002) even after adjusting for larger (6 mm) cryocatheter tips, 'insurance lesions' and longer (>6 months) follow-up duration. RF ablation for AVNRT was associated with permanent AV block in 0.75% of patients, but was not reported in any patients treated with cryoablation (n = 1066, P = 0.01). Conclusions Cryoablation is a safe and effective treatment for AVNRT. Although late-recurrence is more common with cryoablation than with RF ablation, avoidance of permanent AVN block makes it an attractive option in patients where the avoidance of AV block assumes higher priority (such as children and young adults). [ABSTRACT FROM AUTHOR]

Background Anatomical considerations and risks related to x-ray exposure make atrioventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety, and efficacy of performing fluoroless slow-pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents. Methods Twenty-one consecutive patients (mean age 13.5 ± 2.4 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow-pathway potential and performed using a 4-mm-tip catheter. Results Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 95%. Acute success was achieved in 100% of the patients with a median of two cryo-applications. Fluoroless ablation was feasible in 19 patients, while in two subjects 50 seconds and 45 seconds of x-ray were needed due to difficult progression of the catheters along the venous system. After a mean follow-up of 25 months, AVNRT recurred in five patients. All the recurrences were successfully treated with a second procedure. In three patients, a fluoroless cryoablation with a 6-mm-tip catheter was successfully performed, while in the remaining two patients, a single pulse of 60 seconds of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred. Conclusions Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow-pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow-pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures. [ABSTRACT FROM AUTHOR]

Background Inducibility of sustained tachycardia is preferred prior to cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT). Method The Pediatric Electrophysiology Database of a single institution was retrospectively reviewed for patients with clinical sustained (≥30 seconds of symptoms) AVNRT documented by noninvasive means who underwent cryoablation for AVNRT to determine if intermediate-term success with cryoablation for AVNRT can be achieved without inducibility of sustained AVNRT during electrophysiology study (EPS). Results There were no differences between patients with sustained (≥30 seconds of tachycardia) AVNRT (N = 67) and patients with nonsustained (ns, ≥3 beats and <30 seconds of tachycardia) AVNRT at EPS (N = 16). Acute success was achieved without PR prolongation in all patients. Although duration of follow-up was shorter for the sustained group than the nonsustained group (2.7 ± 1.6 years vs 3.8 ± 1.4 years, P = 0.008), recurrence rate was similar (6% vs 6.3%, P = 0.6). In patients with only nonsustained AVNRT at EPS, supportive findings for procedural effectiveness seen: (1) Dual atrioventricular node physiology (DAVNP) was eliminated in 14/14, (2) the fast pathway effective refractory period (FPERP) decreased after ablation in 10/11, (3) sustained slow pathway conduction was eliminated in 8/8 including both patients without discrete DAVNP prior to ablation, and (4) FPERP increased during lesion formation in 10/10. Conclusion Intermediate-term success can be achieved with cryoablation of ns AVNRT. Attention should be paid to supportive indicators of damage to slow pathway. [ABSTRACT FROM AUTHOR]

A case of radiofrequency catheter ablation of atrioventricular (AV) nodal reentry tachycardia, in a patient with transposition of the great arteries after venous rerouting according to Mustard, is described. An electroanatomical map of the His and AV nodal region was created from inside the systemic venous atrium. Retrograde mapping of the pulmonary venous atrium was performed and the arterial catheter retracted to a position in close proximity to the venous catheter inside the intraatrial baffle. This position was chosen to deliver radiofrequency current. (PACE 2012; 35:e287-e290) [ABSTRACT FROM AUTHOR]

The article presents a case study of a 43 year old female patient who presented to an emergency room with heart palpitations and received a diagnosis of irregular narrow complex tachycardia. A discussion of the mechanisms which could have led to the patient's narrow complex tachycardia is presented.

Slow-pathway ablation is the treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT). Cryoablation is effective and safe, but its widespread use seems to be limited by a slightly lower long-term clinical efficacy when compared to radiofrequency (RF) ablation. However, the occurrence of atrioventricular block requiring permanent pacing with RF remains clinically relevant (about 1%). This review summarizes current experiences accumulated during the last decade with cryotechnology in terms of acute and long-term results for AVNRT and compares it with those of RF ablation. We describe the advantages of cryo compared to RF ablation. Our data suggest that pursuing procedural endpoint up to slow pathway complete ablation may improve long-term clinical success of cryoablation. We also focus on potential benefit that can be expected by using cryocatheters leading to larger and deeper freeze. For high-risk ablations, cryoenergy should be used systematically. (PACE 2012; 35:233-240) [ABSTRACT FROM AUTHOR]

The article discusses the mechanism in repetitive nonsustained supraventricular tachycardia. The case involves the onset of unsustained narrow complex tachycardia with variable ventriculoatrial relationship in a 59-year-old woman. A differential diagnosis includes junctional ectopic tachycardia, atroventricular (AV) nodal reentry tachycardia, multifocal atrial tachycardia with bystander accessory pathway, or focal atrial tachycardia combined with orthodromic AV reentry.

The author reflects on atrioventricular node reentrant tachycardia and on the article "Spontaneously Alternating Forms of the Atrioventricular Node Reentrant Tachycardia," by X. Liu, T. Liu, M. Shehata, A. Nahapetian, A. Amorn, S. Chugh and X. Wang. He suggests that reentrant tachycardia is in many ways the poster child for invasive cardiac electrophysiology. He argues that the research which Liu did should serve as an example for all who see phenomena in the electrophysiology laboratory.

Dual atrioventricular (AV) nodal physiology is a substrate for the development of AV nodal reentrant tachycardia (AVNRT). However, the risk of developing AVNRT in patients with dual AV nodal physiology is not known. The purpose of this study is to identify the risk of developing AVNRT in children and adolescents with incidental findings of dual AV nodal physiology after accessory pathway ablation. This is a single center retrospective study of patients who underwent intracardiac electrophysiology study at The Children's Hospital, Denver, from March 1993 to August 2008, with findings of dual AV nodal physiology after successful ablation of an accessory pathway. Follow-up was obtained by chart review with the primary outcome of recurrent supraventricular tachycardia. Extended clinical follow-up was also achieved through phone contact with patients or parents of patients. Mean age at initial electrophysiology study was 12.8 years (±3.7 years). Follow-up was obtained on all 66 patients for a mean duration of 3.1 years (±2.8 years). Mean age at follow-up was 15.8 years (±4.6 years). Recurrent supraventricular tachycardia occurred in nine of the 66 patients (13.6%). AVNRT was induced in two of the 66 patients (3.0%). This study supports the hypothesis that incidental dual AV nodal physiology does not predict AVNRT in children and adolescents with after successful accessory pathway ablation. (PACE 2010; 33:1528-1532) [ABSTRACT FROM AUTHOR]

Entrainment from the right ventricular (RV) apex and the base has been used to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentry tachycardia (AVNRT). The difference in the entrainment response from the RV apex in comparison with the RV base has not been tested. Fifty-nine consecutive patients referred for ablation of supraventricular tachycardia (SVT) were included. Entrainment of SVT was performed from the RV apex and base, pacing at 10-40-ms faster than the tachycardia cycle length. SA interval was calculated from stimulus to earliest atrial electrogram. Ventricle to atrium (VA) interval was measured from the RV electrogram (apex and base) to the earliest atrial electrogram during tachycardia. The SA-VA interval from apex and base was measured and the difference between them was calculated. Thirty-six AVNRT and 23 AVRT patients were enrolled. Mean age was 44 ± 12 years; 52% were male. The [SA-VA]apex-[SA-VA]base was demonstrable in 84.7% of patients and measured −9.4 ± 6.6 in AVNRT and 10 ± 11.3 in AVRT, P < 0.001. The difference was negative for all AVNRT cases and positive for all septal accessory pathways (APs). The difference between entrainment from the apex and base is readily performed and is diagnostic for all AVNRTs and septal APs. (PACE 2010; 1335-1341) [ABSTRACT FROM AUTHOR]

Background: Cryoablation with 4- and 6-mm tip ablation catheters has been demonstrated to be safe and effective in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT) in pediatric patients, albeit with a higher rate of clinical recurrence. Limited information is available regarding efficacy, mid-term outcomes, and complications related to the use of the 8-mm Freezor Max Cryoablation catheter (Medtronic, Minneapolis, MN, USA) in pediatric patients. Methods: We performed a retrospective review of all pediatric patients with normal cardiac anatomy who underwent an ablation procedure for treatment of AVNRT using the 8-mm tip Cryoablation catheter at three large pediatric academic arrhythmia centers. Results: Cryoablation with an 8-mm tip catheter was performed in 77 patients for treatment of AVNRT (female n = 40 [52%], age 14.8 ± 2.2 years, weight 62.0 ± 13.9 kg). Initial procedural success was achieved in 69 patients (69/76, 91%). Transient second- or third-degree atrioventricular (AV) block was noted in five patients (6.5%). There was no permanent AV block. Of the patients successfully ablated with Cryotherapy, there were two recurrences (2/70, 2.8%) over a follow-up of 11.6 ± 3.3 months. Conclusion: Cryoablation with an 8-mm tip ablation catheter is both safe and effective with a low risk of recurrence for the treatment of AVNRT in pediatric patients. (PACE 2010; 33:681–686) [ABSTRACT FROM AUTHOR]