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Purpose: This article, the first in a 2-part review, aims to reinforce current literature on the pathophysiology of cardiac arrhythmias and various evidence-based treatment approaches and clinical considerations in the acute care setting. Part 1 of this series focuses on atrial arrhythmias., Summary: Arrhythmias are prevalent throughout the world and a common presenting condition in the emergency department (ED) setting. Atrial fibrillation (AF) is the most common arrhythmia worldwide and expected to increase in prevalence. Treatment approaches have evolved over time with advances in catheter-directed ablation. Based on historic trials, heart rate control has been the long-standing accepted outpatient treatment modality for AF, but the use of antiarrhythmics is often still indicated for AF in the acute setting, and ED pharmacists should be prepared and poised to help in AF management. Other atrial arrhythmias include atrial flutter (AFL), atrioventricular nodal reentry tachycardia (AVNRT), and atrioventricular reentrant tachycardia (AVRT), which warrant distinction due to their unique pathophysiology and because each requires a different approach to utilization of antiarrhythmics. Atrial arrhythmias are typically associated with greater hemodynamic stability than ventricular arrhythmias but still require nuanced management according to patient subset and risk factors. Since antiarrhythmics can also be proarrhythmic, they may destabilize the patient due to adverse effects, many of which are the focus of black-box label warnings that can be overreaching and limit treatment options. Electrical cardioversion for atrial arrhythmias is generally successful and, depending on the setting and/or hemodynamics, often indicated., Conclusion: Atrial arrhythmias arise from a variety of mechanisms, and appropriate treatment depends on various factors. A firm understanding of physiological and pharmacological concepts serves as a foundation for exploring evidence supporting agents, indications, and adverse effects in order to provide appropriate care for patients., (© American Society of Health-System Pharmacists 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations., Competing Interests: Disclosure The authors have no relevant disclosures., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Atrioventricular (AV) reentrant tachycardia is a common type of supraventricular tachycardia (SVT) that occurs in the fetus and neonate. Although many tachycardias resolve within several weeks of birth or respond to medical management, disruptions in the cardiac annulus fibrosus and development of additional accessory pathways may lead to refractory dysrhythmia resulting in fetal hydrops and ultimately, fetal death., Objectives: While accessory pathways have been well documented anatomically in adult and childhood tachyarrhythmias, there are no reports of the histology of these pathways in human fetuses with SVT., Research Design, Subjects, Measures: This is a small case series of 2 fetuses with a history of SVT that resulted in fetal hydrops., Results: In both cases, examination of the cardiac conduction system was unremarkable and examination of the atrioventricular junction revealed a focally thinned and/or discontinuous annulus fibrosus with documented direct continuity between the atrial and ventricular myocardium in 1 case., Conclusions: This case series demonstrates that thinning or absence of the annulus fibrosus is a feature seen in fetal SVT, and the development of subsequent aberrant AV connections due to defective formation of the annulus fibrosus suggests a possible cause for these arrhythmias.

INTRODUCTION: Catheter ablation is a widely used and effective treatment option for many tachyarrhythmic disorders. This study analyzes all ablation cases in German military aircrew over a 17-yr period. Recurrence of different arrhythmias and ablation complications were analyzed with an aim of refining specific recommendations for aircrew employment. METHODS: All cases of catheter ablations in pilots and nonpilot aircrew examined at the German Air Force Centre of Aerospace Medicine from 2004 to 2020 were analyzed for sex, age, concomitant diseases, ablated arrhythmias, complications, recurrences, time elapsed from ablation to reablation, number of ablations, and aeromedical disposition, including restrictions in case of a return to flying duties. RESULTS: There were 36 aircrew who underwent catheter ablation; 7 were ablated for 2 or more different arrhythmias; 10 underwent more than one ablation. Ablated arrhythmias included atrioventricular (AV) nodal re-entrant tachycardias, accessory pathways, focal atrial tachycardias, typical and atypical atrial flutter, atrial fibrillation, and premature atrial and ventricular complexes. Recurrence rates differed between the arrhythmias and were lowest in AV re-entrant tachycardias. Complication rates were low. CONCLUSION: In this aircrew cohort, nearly all aircrew were able to return to flying duties following ablation, albeit some with restrictions. Restrictions depended on the underlying arrhythmia, the ablation procedure, and the symptoms prior to ablation. A basic understanding of different arrhythmias, ablation techniques, and long-term success rates is essential for the AME and for the responsible licensing authority. Close cooperation with an electrophysiologist is necessary prior to and after ablation to ensure optimal management of aircrew with arrythmias. Guettler N, Nicol E, Sammito S. Return to flying after catheter ablation of arrhythmic disorders in military aircrew . Aerosp Med Hum Perform. 2022; 93(10):725-733.

Dual atrioventricular (AV) nodal non-reentrant tachycardia (DAVNNT) is rare phenomenon where dual AV nodal physiology allows a single P wave to conduct down both the slow and fast AV node extensions resulting in two ventricular beats. We present a case of DAVNNT manifest as incessant ventricular triplets resulting in tachycardia-inducted cardiomyopathy. We discuss the underlying electrophysiology for this rare phenomenon, how to diagnose this condition and the appropriate treatment for this syndrome., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

Introduction: Accessory pathway potential often indicates a highly effective ablation target in Wolff-Parkinson-White syndrome., Methods: A 27-year-old female presenting with palpitation underwent an electrophysiology study, who had mild pre-excitation in surface ECG., Results: An accessory pathway with weak anterograde conduction was found. During isoproterenol infusion, the delta wave became prominent, an antidromic AV reentrant tachycardia was then induced. When the pathway was mapped, widely split double pathway potentials were observed at the 12 o'clock site of the tricuspid annulus during mild pre-excitation, demonstrating an example of intra-pathway conduction delay. Ablation at the site caused accelerated pathway rhythm and eliminated the pathway, rendering the tachycardia noninducible., Conclusion: Split pathway potentials can reflect slow conduction in patients with preexcitation., (© 2022 Wiley Periodicals LLC.)

Purpose: The time interval between the onset of the P-wave on electrocardiogram (ECG) and peak A' velocity of the lateral left atrial wall assessed by tissue Doppler imaging (PA-TDI interval) determine total atrial conduction time (TACT) which reflects atrial remodeling and arrhythmic substrate. In this retrospective study, we aimed to assess TACT in patients with atrioventricular nodal reentrant tachycardia (AVNRT) with and without drug-induced type 1 Brugada electrocardiogram ECG pattern (DI-Type 1 BrP) and control subjects., Methods: Study population consisted of 62 consecutive patients (46 women; mean age 44 ± 12 years) undergoing electrophysiological study and ablation for symptomatic, drug-resistant AVNRT, and 42 age-matched and sex-matched control subjects. All patients and control subjects underwent ajmaline challenge test and tissue Doppler imaging., Results: A DI-Type 1 BrP was uncovered in 24 of 62 patients with AVNRT (38.7%). PA-TDI interval was similar among AVNRT patients with and without DI-Type 1 BrP (124 ± 12 ms vs 119 ± 14 ms, respectively, P = .32), but significantly longer in patients with AVNRT with as well as without DI-Type 1 BrP than in control subjects (124 ± 12 ms and 119 ± 14 ms vs 105 ± 11 ms, respectively, P < .001)., Conclusion: The TACT assessed by PA-TDI interval is longer in patients with AVNRT with and without DI-Type 1 BrP than in age-matched and sex-matched healthy control subjects., (© 2021 Wiley Periodicals LLC.)

BACKGROUND Radiofrequency ablation (RFA) is the criterion standard treatment for patients with atrioventricular nodal reentrant tachycardia (AVNRT). Knowledge about RFA in patients with dextrocardia and situs inversus is limited due to their rare incidence and complexity. The incidence of dextrocardia is reported to be 1 in 12 000 births, with situs inversus occurring in one-third of the cases. The incidence of congenital heart disease is about 5% in these patients. However, data on rhythm and conduction disorders in this group of patients are currently limited, making management more difficult owing to their individual anatomy. CASE REPORT We report the case of an obese 21-year-old man with complex congenital heart disease (CCHD) (situs inversus dextrocardia, pulmonary atresia, single ventricle, common atrium with single atrioventricular valve), asplenia, and multiple cardiac-corrective surgeries (Fontan repair, bidirectional Glenn anastomosis, and Blalock-Taussig shunt) who underwent successful RFA of recurrent supraventricular tachycardia. CONCLUSIONS Supraventricular arrhythmias are common in the setting of CCHD. Although catheter ablation procedures are technically challenging to perform in patients with CCHD, they remain the best therapeutic option for these arrhythmias. To our knowledge, this case is the first to be described in the literature of successful ablation of AVNRT in a patient with situs inversus dextrocardia, pulmonary atresia, a single ventricle, a common atrium with a single atrioventricular valve, and multiple cardiac-corrective surgeries.

Rationale: Dextrocardia is a rare congenital heart disease, while the persistent left superior vena cava (PLSVC) is an uncommon congenital vascular malformation. It is extremely rare for a person to have dextrocardia and PLSVC. A case with a combination of dextrocardia, PLSVC, and atrioventricular nodal reentrant tachycardia has not been reported., Patient Concerns: A 51-year-old woman was admitted to the hospital with palpitations. The physical examination revealed a heart rate of patient increased significantly, and that apex beating was found in the right fifth intercostal space approximately 0.5 cm from the midclavicular line., Diagnosis: We used different techniques, including electrocardiography, esophagus heart electrophysiology, chest radiograph, and cardiac color Doppler echocardiography to reveal the presence of the combination of dextrocardia, PLSVC, and supraventricular tachycardia., Interventions: We terminated tachycardia by esophageal pacing and cured patients with radiofrequency catheter ablation (RFCA)., Outcomes: The complex structural anomalies presented great technical challenges for interventional treatments. After consulting the literature, thorough examination and understanding of the structural anatomy and anomalies of the vena cava and cardiac chambers, we successfully treated this patient by RFCA. After half a year of follow-up, the patient did not have palpitations, and no arrhythmia was seen on the electrocardiography., Lessons: Physicians need to be aware that the key to the success of RFCA, in this case, is to clarify the complexity of the morphological and anatomical structures of dextrocardia accompanying PLSVC and to consult and understand the experience of access vessels reported in relevant cases before the operation.

Background: In atrioventricular nodal reentrant tachycardia (AVNRT), catheter ablation is considered as first-line therapy. Despite high success rates, some patients present with arrhythmia recurrence or develop other types of arrhythmias over time., Objective: To assess the incidence of symptomatic arrhythmias after initially successful AVNRT ablation and to analyze their clinical implications in a real-world cohort., Methods: We included 2,795 patients from the German Ablation Registry undergoing first ablation of AVNRT between 01/2007 and 01/2010. In patients alive at long-term follow-up, patient-specific characteristics and long-term follow-up data were compared between patients with (group A) and without (group B) any symptomatic arrhythmia during follow-up., Results: Symptomatic arrhythmias occurred in 17.2% of patients during a mean follow-up of 678 days after AVNRT ablation. The patients with symptomatic arrhythmias were more often female and suffered from structural heart disease. Arrhythmia occurrence was clinically relevant regarding symptoms and patient satisfaction. Serious adverse events including stroke, transient ischemic attack, pacemaker implantation, as well as continued use of antiarrhythmic medication occurred more often in group A. A second ablation procedure was performed in 26% of symptomatic patients to optimize the symptomatic outcome, whereas cardiovascular events or patient satisfaction were not further improved., Conclusion: During long-term follow-up, one out of six patients experienced symptomatic arrhythmias after AVNRT ablation, associated with an increase of serious adverse events. A subset of patients required medical or interventional antiarrhythmic therapy, possibly attributable to the co-existence of other arrhythmias. Screening for arrhythmic and cardiac co-morbidity before and after ablation may support comprehensive therapy planning and outcome.

Rationale: Tachycardia-induced cardiomyopathy (TIC) is defined as systolic and/or diastolic dysfunction of the left ventricle resulting from prolonged elevated heart rates, completely reversible upon control of the arrhythmia. Atrioventricular reentrant tachycardia (AVRT) is one of the most frequent causes of TIC. In its incessant form, it is unlikely to be controlled by pharmacological treatment, catheter ablation being the principal therapeutic option. The coexistence of left bundle branch block (LBBB) in patients with AVRT may cause difficulties in the early diagnosis and management of tachycardia because of the wide complex morphology, making it harder to localize the accessory pathway (AP)., Patient Concerns: A 60-year-old woman, presented incessant episodes of palpitations and shortness of breath due to a LBBB tachycardia leading to hemodynamic instability., Diagnosis: The patient had a wide QRS tachycardia, with LBBB morphology and a heart rate of 160/minute. Echocardiography showed global hypokinesia with 25% left ventricular ejection fraction (LVEF). Considering the patient's clinical picture, TIC was suspected., Interventions: The electrophysiological study revealed a left lateral accessory pathway. Catheter ablation was successfully performed at the level of the lateral mitral ring., Outcomes: One week after the ablation the patient had no signs of heart failure and the LVEF normalized to 55%. During 6-months follow-up the patient presented no more episodes of tachycardia or heart failure and the LVEF remained normal., Lessons: AVRT is rarely associated with intrinsic LBBB, being a potential cause of TIC. In these patients, it is unlikely to control the arrhythmia pharmacologically, catheter ablation being the best therapeutic option. The variation of QRS complex duration between LBBB pattern in SR and AVRT could be useful for early diagnosis of an ipsilateral AP on surface ECG.

Background: Dextrocardia with situs inversus is a rare cardiac positional anomaly. Catheter ablation procedures performed in this set of patients have not been sufficiently reported., Methods: A total of 10 patients with dextrocardia and situs inversus who received catheter ablation for supraventricular tachycardia (SVT) were included from a cohort of over 20 000 cases of catheter ablation for SVT in three centers from 2005 to 2016. All patients underwent electrophysiologic study and catheter ablation of SVT. Ablation targets were selected based on different tachycardia mechanisms with the primary endpoint of noninduction of tachycardia., Results: The average age was 32.4 ± 5.6 years. Congenitally corrected transposition of great arteries (TGA) with situs inversus and D-looping of the ventricles and aorta (congenitally corrected TGA {I,D,D}) was found in four patients, while the other six patients exhibited mirror-image dextrocardia {I,L,L}. The mechanisms of SVT were atrioventricular nodal reentrant tachycardia in four patients, atrioventricular reentrant tachycardia in three, typical atrial flutter in one, intra-atrial reentrant tachycardia in one, and focal atrial tachycardia in one. Immediate procedural success was achieved in 9 out of 10 patients with no procedural complications. During a follow-up period of 6.3 ± 3.5 years on average, all patients remained free from recurrent tachycardia., Conclusions: For patients with dextrocardia and situs inversus, catheter ablation of SVT is safe and feasible. Differences in catheter maneuver and fluroscopy projection, along with difficulties in distorted anatomy are major obstacles for successful ablation., (© 2019 Wiley Periodicals, Inc.)

Rationale: Atrioventricular reentrant tachycardia (AVRT) is the most common supraventricular tachycardia occurring in children. However, in complex congenital heart disease patients with a different heart anatomy and conduction system morphology, accessory pathway modification may be particularly challenging because of distortion of typical anatomic landmarks., Patient Concerns: A 10-year-old boy with tricuspid atresia and history of bidirectional Glenn operation had recurrent chest distress and palpitation for 3 months. He had multiple hospitalizations for narrow-QRS tachycardia with poor hemodynamic tolerance, despite the use of adenosine and amiodarone., Diagnoses: AVRT. Tricuspid atresia with secundum atrial septal defect, large ventricular septal defect, and right ventricular outflow tract stenosis., Interventions: Cardiac catheterization, electrophysiological examination, and ablation., Outcomes: The child has not had a recurrent AVRT during 6 months of follow-up and is waiting for Fontan operation., Lessons: Since there is an increased risk of accessory pathways in patients with tricuspid atresia, all these patients should be checked before the Fontan operation to exclude congenital accessory pathways.

Background: Atrial arrhythmias, particularly atrioventricular nodal reentrant tachycardia, can coexist with drug-induced type 1 Brugada electrocardiogram (ECG) pattern (DI-Type1-BrP). The present study was designed to determine the prevalence of DI-Type1-BrP in patients with atrioventricular accessory pathways (AV-APs) and to investigate the clinical, electrocardiographic, electrophysiologic, and genetic characteristics of these patients., Methods: One-hundred twenty-four consecutive cases of AV-APs and 84 controls underwent an ajmaline challenge test to unmask DI-Type1-BrP. Genetic screening and analysis was performed in 55 of the cases (19 with and 36 without DI-Type1-BrP)., Results: Patients with AV-APs were significantly more likely than controls to have a Type1-BrP unmasked (16.1 vs 4.8%, P = 0.012). At baseline, patients with DI-Type1-BrP had higher prevalence of chest pain, QR/rSr' pattern in V 1 and QRS notching/slurring in V 2 and aVL during preexcitation, rSr' pattern in V 1 -V 2 , and QRS notching/slurring in aVL during orthodromic atrioventricular reentrant tachycardia (AVRT) compared to patients without DI-Type1-BrP. Abnormal QRS configuration (QRS notching/slurring and/or fragmentation) in V 2 during preexcitation was present in all patients with DI-Type1 BrP. The prevalence of spontaneous preexcited atrial fibrillation (AF) and history of AF were similar (15% vs 18.3%, P = 0.726) in patients with and without DI-Type1-BrP, respectively. The prevalence of mutations in Brugada-susceptibility genes was higher (36.8% vs 8.3%, P = 0.02) in patients with DI-Type1-BrP compared to patients without DI-Type1-BrP., Conclusions: DI-Type1-BrP is relatively common in patients with AV-APs. We identify 12-lead ECG characteristics during preexcitation and orthodromic AVRT that point to an underlying type1-BrP, portending an increased probability for development of malignant arrhythmias., (© 2018 Wiley Periodicals, Inc.)

A 25 year old lady presented with palpitation to the emergency department. Her pulse rate was 210 beats per minute. She was hemodynamically stable with a blood pressure of 100/60 mm Hg. 12 lead surface electrocardiogram (ECG) was recorded during the presentation (Fig. 1) and rhythm strip (Fig. 2A) during administration of IV adenosine. What is the likely diagnosis?, (Copyright © 2018 Elsevier Inc. All rights reserved.)

A 15-year-old female patient presented at the clinic with heart failure (HF). A 12-lead electrocardiogram showed a heart rate of 170 bpm; negative P waves in leads DII, DIII, aVF; and long RP tachycardia (LRPT). Echocardiography demonstrated a shortening fraction (SF) of 20%. An electrophysiology study during tachycardia revealed an atrial-His time of 52 milliseconds and a His-atrial interval of 295 milliseconds. During ventricular entrainment, the postpacing interval-tachycardia cycle length was measured at 225 milliseconds. There was a pseudo V-A-A-V response. These findings confirmed the diagnosis of atypical atrioventricular nodal re-entrant tachycardia (aAVNRT). Successful slow pathway cryoablation was performed with an 8-mm-tip cryocatheter. After 2 weeks, the SF was measured as 34%. During a 2-year follow-up period, no recurrence was observed. In conclusion, fast-slow aAVNRT should be a part of the differential diagnosis of incessant LRPT leading to HF. Cryoablation can be used successfully in cases of aAVNRT.

Rationale: Dual atrioventricular nodal non-reentrant tachycardia (DAVNNT) is an uncommon arrhythmia. Because of the different refractory periods of fast and slow pathways, a single atrial depolarization gives rise to 2 ventricular activationsthrough fast and slow pathways separately., Patient Concerns: A 45-year-old woman was referred to our Cardiology Center with symptoms of recurrent palpitations and fatigue persisting for the previous 3 years. On echocardiography, the ejection fraction of the left ventricle was 45%., Diagnoses: Electrophysiological study findings and 12-lead electrocardiogram led to a diagnosis of DAVNNT., Interventions: Our case responded very well to the ablation of the slow pathway, and her tachycardia completely disappeared., Outcome: Her left ventricle ejection fraction also improved to52% after 3 months of follow-up. The patient remained asymptomatic throughout the follow-up period of 1 year, without any recurrence or complications., Lessons: DAVNNT is a rare arrhythmia which can induce tachycardia-induced cardiomyopathy. Ablation of the slow pathway isconsidered a curative treatment.

BACKGROUND Lown-Ganong-Levine syndrome, includes a short PR interval, normal QRS complex, and paroxysmal tachycardia. The pathophysiology of this syndrome includes an accessory pathway connecting the atria and the atrioventricular (AV) node (James fiber), or between the atria and the His bundle (Brechenmacher fiber). Similar features are seen in enhanced atrioventricular nodal conduction (EAVNC), with the underlying pathophysiology due to a fast pathway to the AV node, and with the diagnosis requiring specific electrophysiologic criteria. CASE REPORT A 17-year-old man presented with a history of recurrent narrow-complex and wide-complex tachycardia on electrocardiogram (ECG). An electrophysiologic study showed an unusually short atrial to His (AH) conduction interval and a normal His to ventricle (HV) interval, without a delta wave. Two stable AH intervals coexisted in the same atrial pacing cycle length. In the recovery curve study, this pathway had a flat conduction curve without an AH increase until the last 60 ms, before reaching the effective refractory period. These ECG changes did not respond to an adenosine challenge. When this pathway became intermittent, there was a paradoxical response to adenosine challenge with conduction via a short AH interval, but without conduction block. Catheter ablation of the AV nodal region resulted in a normalized AH interval, decremental conduction properties, and resulted in a positive response to an adenosine challenge. CONCLUSIONS In this case of Lown-Ganong-Levine syndrome, electrophysiologic studies supported the role of the accessory pathway of James fibers.

Introduction: Muscular connections between the coronary sinus (CS) and left atrium probably impact distribution of electrical activity. Double atrial potentials (DP) may be their presentation. The aim was to investigate the presence of DP in CS recordings during atrioventricular reentrant tachycardia (AVRT) and its contribution to the occurrence of paroxysmal atrial fibrillation (AF)., Methods: A group of 247 patients with accessory pathways (AP) were screened for DP. The patients with DP during AVRT were compared to those without DP., Results: DP during AVRT were found only among the left-sided AP (AP-L). Patients with AP-L were divided into Group 1 (n  =  17) with DP during AVRT and Group 2 (n  =  108) without DP. Patients in Group 1 had higher incidence of AF in history (47.1% vs. 23.1%; P  =  0.0376), AF induced during electrophysiological (EP) study (70.6% vs. 25%; P  =  0.0002). Group 1 had higher heart rate (HR) during AVRT in the EP study (197.2 ± 27 vs. 175.1 ± 26.3 bpm; P  =  0.0019), but HR of clinical AVRT (208.5 ± 30.8 vs. 191.6 ± 27.8 bpm) was not significant different (P  =  ns). Additionally, electrical alternans of QRS amplitude during AVRT in the EP study was more frequent in Group 1 (52.9 vs. 20.4 %; P  =  0.0048)., Conclusion: Patients with DP and AP-L were more prone to develop AF. The presence of DP was associated with faster AVRT rate. The direction of atrium depolarization during AVRT may be different in the presence of DP and probably plays a role in development of AF in this group of patients., (© 2017 Wiley Periodicals, Inc.)

Aims: We sought to investigate focal atrial tachycardias (ATs) in patients with congenitally corrected transposition of the great arteries (ccTGA)., Methods and Results: We identified three cases of focal ATs with ccTGA from 2007 to 2015. The clinical findings, electrocardiography, electrophysiological features, and ablation were reported. All three cases had {S,L,L}-type ccTGA. The AT P waves shared the following features: narrow in width, positive in leads I and aVL, and negative/positive in lead V1. All ATs had focal activation pattern with early activation at the anteroseptal area, and further mapping demonstrated earliest atrial activation (EAA) inside the pulmonary sinus cusps (PSCs), especially the right PSC. In Cases 1 and 2, double potentials were recorded at the EAA sites. Conduction delay between the two potentials during atrial extrastimulus was observed. After successful ablation, the second potential during sinus rhythm was further delayed in Case 1 and was eliminated in Case 2. However, only one potential was recorded in Case 3. All three cases were successfully managed by ablating the sites with EAA, which preceded the P-wave onset by 60, 80, and 42 ms, respectively. During ablation, no junctional rhythm was observed. Incomplete left bundle branch block was induced during mapping in Case 1, but no other complications occurred. All patients were free from tachycardia during follow-up periods of 36, 7, and 5 months, respectively., Conclusion: Anteroseptal AT in patients with ccTGA could be eliminated by ablation inside the PSC., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Background: Wolff-Parkinson-White (WPW) syndrome and idiopathic left ventricular tachycardia (ILVT) are rare and up to now the coexistence of both entities has rarely been reported. In patients with ventricular preexcitation the underlying mechanism of paroxysmal tachycardia most likely is atrioventricular reentrant tachycardia (AVRT). However, without ECG documentation of the tachycardia diagnosis of the underlying mechanism cannot be made due to similar clinical presentation of AVRT and ILVT., Case Presentation: We report a case of a two-staged occurrence of two rare arrhythmias in a young adult, who was admitted to our hospital twice within 6 months because of paroxysmal tachycardia. WPW syndrome and ILVT as underlying arrhythmias have been diagnosed and were ablated successfully., Conclusions: This case highlights the diagnostic defiance of rare tachycardia entities and the paramount importance of ECG documentation and analysis of all available tachycardia ECGs.

Due to its safety profile, cryoablation (Cryo) for atrioventricular nodal reentrant tachycardia (AVNRT) is more commonly preferred over radiofrequency (RF) ablation in children in recent years. Recent studies demonstrated high long-term success rates comparable to radiofrequency ablation. The aim of this prospective study was to compare the efficacy and safety of an 8-mm-tip versus 6-mm-tip Cryo catheter in the treatment of AVNRT in children. A total of 125 consecutive patients over 10 years of age with AVNRT were included. EnSite system (St. JudeMedical, St Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The acute procedural success was 100% in both groups. The prodecure duration for the 8-mm-tip group was shorter (151.6 ± 63.2 vs. 126.6 ± 36.7 min, p < 0.01, respectively). Fluoroscopy was used in only 7 patients. The mean follow-up duration was 14.6 ± 8.4 months (median 13.5 months, min. 3 months and max. 27 months). The recurrence rate for AVNRT was also comparable between the two groups (6-mm tip: 9.6 vs. 8-mm tip: 8%). Cryo of AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates using 6-mm and 8-mm-tip catheters in children. In addition, procedure duration is shorter with an 8-mm-tip Cryo catheter.

The aim of the study was to evaluate the incidence of different personality types and state and trait anxiety levels in patients with paroxysmal supraventricular tachycardia and their association with patients age, gender and the mechanism of the paroxysmal SVT. 62 patients with documented paroxysmal supraventricular tachycardia who underwent endocardial eletrophysiological study and catheter ablation of the paroxysmal SVT were included in the study. The patients were asked to fill out the Myers-Brigss Type Indicator and State-Trait Anxiety Inventory questionnaires and the results were analyzed and correlated with the arrhythmia mechanism determined during electrophysiological study and catheter ablation procedure, and the patients' demographics (age and gender). There was no significant difference in State (mean 41.53±13.51, p=0.893) or Trait (mean 44.70±12.62, p=0.315) anxiety scores according to gender although higher scores were found in females. Older patients (≥50 years old compared to <50 years old) had higher anxiety scores but with no statistical significance (p=0.344 for state anxiety and p=0.100 for trait anxiety). The patients with AVNRT had significantly higher Trait anxiety scores (mean 46.82±10.52) than the patients with AVRT or AT (mean 40.59±10.91) (p=0.032). State anxiety score was not significantly different between patients with different SVT types (p=0.706). Anxiety is an important factor to be considered in patients with paroxysmal supraventricular tachycardia. It doesn't seem to be associated with different personality types. Female and older patients tend to show higher anxiety levels. The atrioventricular Nodal Reentrant Tachycardia (AVNRT) is associated with significantly higher trait anxiety levels compared to other types of paroxysmal supraventricular tachycardia.

Background: Atrioventricular reciprocating tachycardia (AVRT) utilizing a concealed accessory pathway is common. It is well appreciated that some patients may have multiple accessory pathways with separate atrial and ventricular insertion sites., Methods: We present three cases of AVRT utilizing concealed pathways with evidence that each utilizing a single ventricular insertion and two discrete atrial insertion sites., Results: In case one, two discrete atrial insertion sites were mapped in two separate procedures, and only during the second ablation was the Kent potential identified. Ablation of the Kent potential at this site remote from the two atrial insertion sites resulted in the termination of the retrograde conduction in both pathways. Case two presented with supraventricular tachycardia (SVT) with alternating eccentric atrial activation patterns without alteration in the tachycardia cycle length. The two distinct atrial insertion sites during orthodromic AVRT and ventricular pacing were targeted and each of the two atrial insertion sites were successfully mapped and ablated. In case three, retrograde decremental conduction utilizing both atrial insertion sites was identified prior to ablation. After mapping and ablation of the first discrete atrial insertion site, tachycardia persisted utilizing the second atrial insertion site. Only after ablation of the second atrial insertion site was SVT noninducible, and VA conduction was no longer present., Conclusions: Concealed retrograde accessory pathways with discrete atrial insertion sites may have a common ventricular insertion site. Identification and ablation of the ventricular insertion site or the separate discrete atrial insertion sites result in successful treatment., (© 2017 Wiley Periodicals, Inc.)

A 50-year-old female presented with incessant palpitation of 2 weeks duration. She was hemodynamically stable and there was no evidence of heart failure. A transthoracic echocardiogram showed mild left ventricular (LV) dysfunction with LV ejection fraction of 45%. Electrocardiogram (12 lead and rhythm strip) was taken during the palpitation. What is the mechanism?, (© 2016 Wiley Periodicals, Inc.)

There are limited data on the experience of transbaffle access for catheter ablation in patients who have undergone a Fontan palliation for complex congenital heart. Nevertheless, these issues will be encountered more frequently, because patients who have undergone Fontan palliation continue to survive into adulthood and develop a variety of arrhythmias that may be refractory to medical therapy., (Copyright © 2016 Elsevier Inc. All rights reserved.)

This report illustrates an interesting case of atrioventricular nodal reentrant tachycardia that presented with 2 different ventricular cycle lengths due to a 2:1 block in the lower common pathway. At the induction of the tachycardia, a long-short sequence above the His creates a phase 3 block resulting in a 2:1 conduction in the lower common pathway. A premature ventricular contraction, by retrograde penetration of the His, eliminates the long-short sequence and brings the conduction back to 1:1., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of supraventricular tachycardia. In contrast, Wolff-Parkinson-White (WPW) pattern consists of an accessory pathway, which may result in the development of ventricular arrhythmias. Frequent tachycardia caused by AVNRT and accessory pathways may play a role in left ventricular systolic dysfunction., Case Report: A 54-year-old man presented with palpitations and acute decompensated congestive heart failure. His baseline EKG showed Wolff-Parkinson-White (WPW) pattern. While hospitalized, he had an episode of atrioventricular nodal reentrant tachycardia (AVNRT). He underwent radiofrequency catheter ablation for AVNRT, and his accessory pathway was also ablated even though its conduction was found to be weak. He was clinically doing well on follow-up visit, with resolution of his heart failure symptoms and normalization of left ventricular function on echocardiography., Conclusions: This case raises the question whether the accessory pathway plays a role in the development of systolic dysfunction, and if there is any role for ablation in patients with asymptomatic WPW pattern.

Objectives: To jointly study paroxysmal supraventricular tachycardia (SVT)-related adverse events (AE) and ablation-related complications, with specific emphasis on the predictors of SVT-related AE as well as their significance by investigating their association with long-term mortality., Methods: 1770 patients were included, aged 6 to 97, with either atrioventricular nodal reentrant tachycardia (AVNRT) or orthodromic atrioventricular reciprocal tachycardia (AVRT) mediated by concealed accessory pathway, consecutively referred for SVT work-up in a tertiary care center., Results: SVT-related AE were identified in 339 patients (19%). Major AEs were identified in 23 patients (1%; 15 cardiac arrests or ventricular arrhythmias requiring cardioversion and 8 hemodynamic collapses). Other AE were related to syncope (n=236), acute coronary syndrome (n=57) and heart failure/rhythmic cardiomyopathy (n=21). In multivariable analysis, higher age, heart disease and requirement of isoproterenol to induce SVT were independently associated with a higher risk for SVT-related AE. During follow-up (2.8±3.0years), death occurred more frequently in patients with SVT-related AE, especially in patients with major adverse events (p<0.001). In multivariable analysis, major SVT-related AE remained significantly associated with occurrence of death (HR=6.72, IC=(2.58-17.52), p<0.001) independently of age and presence of underlying heart disease. Major SVT-related AE in the whole population referred for SVT were more frequent than immediate major ablation complications in patients undergoing SVT ablation (5/1186 vs. 23/1770, p=0.02)., Conclusions: SVT-related AE are independent predictors of mortality and are more frequent than immediate major ablation complications in patients undergoing SVT ablation. The present findings support systematically performing SVT ablation in patients with SVT-related adverse events., (Copyright © 2015. Published by Elsevier Ireland Ltd.)