Iatrogenic Atrioventricular Block.

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.

Pathophysiology and treatment of adults with arrhythmias in the emergency department, part 1: Atrial arrhythmias.

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.

Fetal Supraventricular Tachycardia: Histologic Evidence of Accessory Pathways Due to Incomplete Annulus Fibrosus Formation.

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.

Return to Flying After Catheter Ablation of Arrhythmic Disorders in Military Aircrew.

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 AV nodal non-reentrant tachycardia-induced cardiomyopathy.

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.

Right-sided Mahaim-mediated tachycardia combined with atypical atrioventricular nodal reentrant tachycardia and left free wall accessory pathway: A case report.

A 37-year-old man was admitted to our hospital with paroxysmal palpitation for half year. A previous electrogram showed a narrow complex tachycardia. Electrophysiologic study (EPS) found a concealed left-sided free wall pathway accessory. In addition, a transseptal approach was used for radiofrequency ablation. After successful ablation, EPS induced a wide complex tachycardia and a narrow complex tachycardia. The wide complex tachycardia was diagnosed as a right-sided Mahaim fiber atriofascicular accessory pathway, and the narrow complex tachycardia was diagnosed as atypical atrioventricular nodal reentrant tachycardia (AVNRT). Then, the right-sided Mahaim fiber atriofascicular accessory pathway and atypical AVNRT were successfully ablated. Herein, we report a rare case of a concealed left-sided accessory pathway combined with a right atriofascicular Mahaim fiber and atypical AVNRT.

Split accessory pathway potentials in a patient with antidromic AVRT.

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.

Assessment of atrial functional remodeling in patients with atrioventricular nodal reentrant tachycardia with and without drug-induced type 1 Brugada pattern: A case-control study.

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.

Successful trans-septal ablation of a left concealed accessory pathway in a patient receiving surgical mitral valve repair and mechanical aortic valve replacement.

We presented a case of severe aortic regurgitation and moderate mitral regurgitation s/p aortic valve replacement and mitral valve repair. Deterioration of tachyarrhythmia attacks was noted. In EP study, left lateral accessory pathway with orthodromic atrioventricular reentrant tachycardia was identified. We successfully ablated the accessory pathway by trans-septal approach. Even though trans-septal approach currently is a daily routine of invasive interventional electrophysiologists, in this case, we want to emphasize and illustrate the distance between true mitral annulus and coronary sinus. Unrecognizing this concept could result in efficacy and safety of catheter-based therapy.

Successful Radiofrequency Ablation of Recurrent Supraventricular Tachycardia in a Patient with Complex Congenital Heart Disease.

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.

Radiofrequency catheter ablation in a patient with dextrocardia, persistent left superior vena cava, and atrioventricular nodal reentrant tachycardia: A case report.

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.

Symptomatic arrhythmias after catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT): results from the German Ablation Registry.

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.

Tachycardia-induced cardiomyopathy in a patient with left-sided accessory pathway and left bundle branch block: A case report.

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.

Atrioventricular reentrant tachycardia in a child with tricuspid atresia: A case report of catheter ablation.

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.

Catheter ablation of supraventricular tachycardia in patients with dextrocardia and situs inversus.

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.