Contemporary Patients With Congenital Heart Disease: Uniform Atrial Tachycardia Substrates Allow for Clear Ablation Endpoints With Improved Long-Term Outcome.

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Characteristics of a large-scale cohort with accessory pathway(s): A cross-sectional retrospective study highlighting over a twenty-year experience.

OBJECTIVE: Catheter ablation following electrophysiologic study (EPS) is the mainstay of diagnosis and treatment for patients with atrioventricular reentrant tachycardia (AVRT), demonstrating excellent long-term outcome and a low rate of complications. In this study, our aim was to assess our experience in patients with accessory pathway (AP) and to compare our data with the literature. METHODS: We included 1,437 patients who were diagnosed and treated for AP in our hospital between 1998 and 2020. The demographic data of all the patients, AP location, and periprocedural results were recorded. RESULTS: Of the 1,437 patients, 1,299 (90.4%) were men; and the mean age of the population was 26.67 years. The location of 1,418 APs were along the left free wall (647 [45.6%] patients), in the posteroseptal region (366 [25.3%] patients), in the anteroseptal region (290 [20.4%] patients), and along the right free wall (115 [8.1%] patients). The ratio of the second AP existence was 3.0% and AVNRT co-existence was 2.0%. A total of 55 (3.8%) patients had recurrent sessions for relapse. Our center's total success rate was 95.5%, and total complication rate was 0.26%. CONCLUSION: According to our retrospective analysis, EPS is a highly functional tool in the diagnosis and management of arrhythmias such as AVRT for high-risk patient groups like military personnel with the aim of risk stratification and medical management.

Long-term outcomes of arrhythmia and distinct electrophysiological features in congenitally corrected transposition of the great arteries in an Asian cohort.

Congenitally corrected transposition of the great arteries (ccTGA) is associated with various types of arrhythmia, including supraventricular tachycardia (SVT) and complete atrioventricular block (cAVB). Our study aims to characterize the arrhythmia burden, associated risk factors, arrhythmia mechanisms, and the long-term follow-up results in patients with ccTGA in a large Asian cohort. METHODS: We enrolled 104 patients (43 women and 61 men) diagnosed with ccTGA at our institution. The mean age at last follow-up was 20.8 years. RESULTS: For 40 patients (38%) with tachyarrhythmia, paroxysmal SVT (PSVT) and atrial arrhythmia were observed in 17 (16%) and 27 (26%) patients, respectively, with 4 patients (4%) having both types of SVT. The 20-year and 30-year SVT-free survival rates were 68% and 54%, respectively. Seven patients (7%) developed cAVB: 2 (2%) developed spontaneously, and the other 5 (5%) was surgically complicated (surgical risk of cAVB: 7%, all associated with ventricular septal defect repair surgery). PSVT was mostly associated with accessory pathways (5/9) but also related to twin atrioventricular nodal reentry tachycardia (3/9) and atrioventricular nodal reentry tachycardia (1/9). Most of the accessory pathways were located at tricuspid valve (9/10). Catheter ablation successfully eliminated all PSVT substrates (10/10) and most of the atrial arrhythmia substrates (3/5), with low recurrence rate. CONCLUSIONS: The arrhythmia burden in patients with ccTGA is high and increases over time. However, cAVB incidence was relatively low and kept stationary in this Asian cohort. The mechanisms of SVT are complicated and can be controlled through catheter ablation.

Long-term symptom improvement and patient satisfaction following catheter ablation of supraventricular tachycardia: insights from the German ablation registry.

AIMS: To analyse outcomes of supraventricular tachycardia (SVT) ablations performed within a prospective German Ablation Quality Registry. METHODS AND RESULTS: Data from 12 566 patients who underwent catheter ablation of SVT between January 2007 and January 2010 to treat atrial fibrillation (AFIB, 37.2% of procedures), atrial flutter (AFL, 29.9%), atrioventricular nodal re-entrant tachycardia (AVNRT, 23.2%), atrioventricular re-entrant tachycardia (6.3%), and focal atrial tachycardia (AT, 3.4%) were prospectively collected. Patients were followed for at least 1 year. The periprocedural success rate was 96.3%, ranging from 84.3% (focal AT) to 98.9% (AVNRT). Kaplan-Meier mortality estimate at 1 year was 1.4% overall, and as high as 2.6% in the AFL group and 2.8% in the focal AT group. Recurrence of ablated or another symptomatic SVT was observed in 3783 (32.6%) of patients, ranging from 17.2% (AVNRT) to 45.6% (AFIB). Repeat ablation was performed in 12.0% of patients. After 1 year, 74.1% of survivors perceived ablation therapy as successful, 15.7% as partly successful, and 9.6% as unsuccessful. Even in those patients with arrhythmia recurrence, 76.0% perceived ablation as successful or partly successful and 89.6% would still undergo repeat ablation in the same institution. CONCLUSION: Ablation therapy for SVT is a safe procedure bringing symptomatic improvement and satisfaction to three quarters of patients after 1 year. Even in patients with arrhythmia recurrence, a high satisfaction level and adherence to the ablating institution could be documented. Strikingly high mortality and stroke rates in follow-up were observed in AFL patients, who apparently need consistent long-term anticoagulation and more medical attention.

Management of supraventricular arrhythmias in adults with congenital heart disease.

Supraventricular arrhythmias are a frequent complication in adults with congenital heart disease (ACHD). The prevalence increases with time since surgery, complexity of the underlying defect, type of repair and older age at surgery. Arrhythmias are the most frequent reason for hospital admission and along with heart failure the leading cause of death. The arrhythmia-associated increase in morbidity and mortality makes their management a key task in patients with ACHD. Intra-atrial re-entry is the most frequent arrhythmia mechanism. Less common arrhythmia mechanisms are supraventricular tachycardias in the presence of an accessory pathway, atrioventricular nodal re-entrant tachycardia or focal tachycardias. Patient management includes stroke prevention, acute termination and prevention of arrhythmia recurrence. Acute treatment depends on patients' symptoms. In cases of haemodynamic instability, immediate cardioversion is warranted. For stable patients, acute treatment includes rate control and termination by antiarrhythmic drugs or electrical cardioversion. Following a symptomatic arrhythmia, catheter ablation or treatment with antiarrhythmic drugs is recommended to prevent recurrences. Advances in mapping and ablation technology are now associated with high success rates of catheter ablation. In patients with a complex substrate recurrence rates of 50% remain high. However, in the presence of side effects and complications associated with long-term antiarrhythmic drug therapy, redo procedures are encouraged by current guidelines.

Hot topics in tetralogy of Fallot.

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. We explore "hot topics" to highlight areas of emerging science for clinicians and scientists in moving toward a better understanding of the long-term management of patients with repaired TOF. From a genetic perspective, the etiology of TOF is multifactorial, with a familial recurrence risk of 3%. Cardiac magnetic resonance is the gold standard assessment tool based on its superior imaging of the right ventricular (RV) outflow tract, pulmonary arteries, aorta, and aortopulmonary collaterals, and on its ability to quantify biventricular size and function, pulmonary regurgitation (PR), and myocardial viability. Atrial re-entrant tachycardia will develop in more than 30% of patients, and high-grade ventricular arrhythmias will be seen in about 10% of patients. The overall incidence of sudden cardiac death is estimated at 0.2%/yr. Risk stratification, even with electrophysiologic testing and cardiac magnetic resonance, remains imperfect. Drug therapy has largely been abandoned, and defibrillator placement, despite its high risks for complications and inappropriate discharges, is often recommended for patients at higher risk. Definitive information about optimal surgical strategies for primary repair to preserve RV function, reduce arrhythmia, and optimize functional status is lacking. Post-operative lesions are often amenable to transcatheter intervention. In selected cases, PR may be treated with transcatheter valve insertion. Ongoing surveillance of RV function is a crucial component of clinical assessment. Except for resynchronization with biventricular pacing, no medical therapies have been shown to be effective after RV dysfunction occurs. In patients with significant PR with RV dilation, optimal timing of pulmonary valve replacement remains uncertain, although accepted criteria are emerging.

Electrophysiological features differentiating the atypical atrioventricular node-dependent long RP supraventricular tachycardias.

BACKGROUND: Diagnosing atypical atrioventricular node-dependent long RP supraventricular tachycardias (SVTs) can be challenging. METHODS AND RESULTS: Nineteen patients with 20 SVTs (atypical atrioventricular nodal reentrant tachycardia without [n=11]/with [n=3] a bystander nodofascicular [NF] accessory pathway, orthodromic reciprocating tachycardia [ORT] using a decremental atrioventricular [permanent form of junctional reciprocating tachycardia; n=4] or NF [NF reentrant tachycardia; n=2]) accessory pathway underwent electrophysiological study. Postpacing interval (PPI)-tachycardia cycle length (TCL), corrected PPI, VA (ventriculoatrial), HA (His-atrial), AH (atrio-His) values, and responses to His-refractory ventricular premature depolarizations were studied. Compared with atrioventricular nodal reentrant tachycardia, ORT patients were younger (42±13 years versus 54±19 years; P=0.036) and were women (5/6 [83%] versus 3/14 [21%]; P=0.036); TCLs were similar (435 ms versus 429 ms; 95% confidence interval, -47.5 to 35.5). PPI-TCL was shorter for ORT (118 ms versus 176 ms; 95% confidence interval, 26.3-89.7) but only 50% had PPI-TCL <115 ms, whereas 5 of 6 (83%) had PPI-TCL <125 ms (sensitivity, 83%; specificity, 100%). Corrected PPI <110 ms, VA <85 ms, and HA <0 ms had equivalent sensitivity (67%) and 100% specificity for ORT. Compared with permanent form of junctional reciprocating tachycardia, NF reentrant tachycardia/atrioventricular nodal reentrant tachycardia had longer AH (29 ms versus 10 ms; 95% confidence interval, 3.03-35.0) or AH(SVT)

Cryoablation of atrioventricular nodal reentrant tachycardia: a clinical review.

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.

"Near-zero" fluoroscopic exposure in supraventricular arrhythmia ablation using the EnSite NavX™ mapping system: personal experience and review of the literature.

PURPOSE: Radiofrequency catheter ablation (RFCA) of supraventricular tachyarrhythmias carries a small but non-negligible radiation risk. Studies in children already showed the feasibility of using three-dimensional mapping systems as the primary guide for catheter visualization and positioning in these RFCAs. We aim to demonstrate the feasibility and safety of such an approach in young and middle-aged patients. METHODS: Fifty patients (age 34 ± 12) with supraventricular tachyarrhythmias underwent electrophysiological study; of these, 47 patients proceeded to RFCA guided by the EnSite NavX(TM) system (23 with atrioventricular nodal reentry tachycardia, 16 with an accessory pathway, six with typical atrial flutter, and two with right atrial tachycardia). RESULTS: In 38/50 cases (76%), electroanatomical mapping avoided fluoroscopy entirely, including four cases requiring access to the left heart chambers by a retrograde approach. In the remaining 12/50 cases (24%), fluoroscopy use was limited to 122 ± 80 s, with a correspondingly low radiation exposure (dose area product 1.3 ± 1.1 mGy × m(2)). All procedures were acutely successful, with a procedural time of 113 ± 37 minutes, and without incurring in any major complication. Over a mean follow-up of 12 ± 3 months, we observed one recurrence of pre-excitation and one relapse of atrial flutter. CONCLUSIONS: Our study shows that non-fluoroscopic RFCA of supraventricular tachyarrhythmias using the EnSite NavX(TM) system is feasible, safe, and effective in a population of relatively young adults. Our experience of a non-fluoroscopic approach in these procedures deserves consideration, particularly in the young or in other patients at higher radiation risk.

Cryoablation versus radiofrequency energy for the ablation of atrioventricular nodal reentrant tachycardia (the CYRANO Study): results from a large multicenter prospective randomized trial.

BACKGROUND: Cryoablation has emerged as an alternative to radiofrequency catheter ablation (RFCA) for the treatment of atrioventricular (AV) nodal reentrant tachycardia (AVNRT). The purpose of this prospective randomized study was to test whether cryoablation is as effective as RFCA during both short-term and long-term follow-up with a lower risk of permanent AV block. METHODS AND RESULTS: A total of 509 patients underwent slow pathway cryoablation (n=251) or RFCA (n=258). The primary end point was immediate ablation failure, permanent AV block, and AVNRT recurrence during a 6-month follow-up. Secondary end points included procedural parameters, device functionality, and pain perception. Significantly more patients in the cryoablation group than the RFCA group reached the primary end point (12.6% versus 6.3%; P=0.018). Whereas immediate ablation success (96.8% versus 98.4%) and occurrence of permanent AV block (0% versus 0.4%) did not differ, AVNRT recurrence was significantly more frequent in the cryoablation group (9.4% versus 4.4%; P=0.029). In the cryoablation group, procedure duration was longer (138±54 versus 123±48 minutes; P=0.0012) and more device problems occurred (13 versus 2 patients; P=0.033). Pain perception was lower in the cryoablation group (P<0.001). CONCLUSIONS: Cryoablation for AVNRT is as effective as RFCA over the short term but is associated with a higher recurrence rate at the 6-month follow-up. The risk of permanent AV block does not differ significantly between cryoablation and RFCA. The potential benefits of cryoenergy relative to ablation safety and pain perception are counterbalanced by longer procedure times, more device problems, and a high recurrence rate. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00196222.

Paediatric radiofrequency ablation experience at a Venezuelan cardiology facility.

UNLABELLED: Radiofrequency (RF) ablation is a curative treatment for many different types of cardiac arrhythmias but its application has been more limited in the paediatric population. We here describe RF paediatric ablation experience at a 400-bed University Hospital in a western Venezuelan province and compare it with the results reported in other countries. METHODS: One hundred and fifty five patients under 18 years of age who where submitted to RF ablation between 1994 and 2007 were included. The patients were 12.8+/-3.4 year-old (rank: 3-17 years); 59% were female. Nine patients were submitted to more than one procedure. AV nodal re-entrant tachycardia and atrio-ventricular re-entrant tachycardias mediated by accessory pathways made up 83% of the ablations. The overall success rate was 91.5%. In the AV nodal re-entrant tachycardia and atrial flutter, success rate almost reached 100%. Ablation was successful in 93% of the patients with the Wolff-Parkinson-White syndrome. The overall complication rate was 5% with 0.6% of major complications and 0% death rate. The results were comparable to those recently reported by the cooperative paediatric ablation registry in the United States of America and by a large hospital in Taiwan. CONCLUSION: RF ablation is a curative therapy with a high success rate and very low complication rates in the paediatric population at the Cardiovascular Research Institute of the University Hospital of The Andes in Venezuela.

Differentiating junctional tachycardia and atrioventricular node re-entry tachycardia based on response to atrial extrastimulus pacing.

OBJECTIVES: The purpose of this study was to differentiate non-re-entrant junctional tachycardia (JT) and typical atrioventricular node re-entry tachycardia (AVNRT). BACKGROUND: JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. METHODS: We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. RESULTS: In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. CONCLUSIONS: The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.

Cryoablation outcomes for AV nodal reentrant tachycardia comparing 4-mm versus 6-mm electrode-tip catheters.

BACKGROUND: Cryoablation is increasingly used to treat atrioventricular nodal reentrant tachycardia (AVNRT). It is unknown whether larger electrode-tip cryocatheters improve outcomes without compromising safety. OBJECTIVE: This study sought to compare acute and long-term success with 4-mm versus 6-mm electrode-tip cryocatheters for AVNRT. METHODS: We conducted a 2-group cohort study on 289 patients, age 45.5 +/- 15.9 years (76.8% female), who underwent transcatheter cryoablation as a first-time procedure for AVNRT with 4-mm (N = 152) or 6-mm (N = 137) electrode-tip catheters. RESULTS: Acute procedural success was achieved in 90.7% (95% confidence interval 86.9% to 93.7%) with no difference between the 2 electrode-tip sizes. A shorter fluoroscopy time (16.1 +/- 11.3 versus 20.3 +/- 14.9 minutes, P = .0096) and trend toward briefer procedural duration (166.6 +/- 49.1 versus 173.5 +/- 53.0 minutes, P = NS) were noted with 6-mm electrode tips. Transient AV block occurred in 5.2%, with complete recovery in 4.4 +/- 2.6 seconds. Over a median follow-up of 155 days, recurrences were less common with 6-mm electrode tips. Actuarial event-free survival rates at 1, 3, 6, and 12 months with 6-mm versus 4-mm electrode-tip cryocatheters were 96.7%, 93.4%, 91.9%, and 88.5% versus 89.9%, 87.0%, 84.1%, and 77.1%, respectively, with no recurrence thereafter (P = .0457). In multivariate analyses adjusting for baseline imbalances and medical therapy postablation, cryoablation with a 4-mm-tip catheter incurred a 2.5-fold increased risk of recurrence (hazard ratio 2.5, 95% confidence interval 1.0 to 6.1, P = .0420). CONCLUSION: In patients with AVNRT, cryoablation with 6-mm electrode-tip catheters is safe and is associated with fewer recurrences on long-term follow-up compared with 4-mm electrode-tip cryocatheters.

Long-term outcome of patients with atrioventricular node reentrant tachycardia.

BACKGROUND: Little information is available on the natural history of patients with AVNRT. The purpose of this study was to compare the outcome of patients with Atrioventricular node reentrant tachycardia (AVNRT) who underwent ablation with those on antiarrhythmic therapy and those not receiving drugs. METHODS: 93 consecutive patients (mean age=33.5+/-18.1 years) with AVNRT referred to our institution from 1988 to 1993 were prospectively followed-up for a mean of 13.2+/-2.0 years (range=11.4-16.1 years). RESULTS: 18 patients underwent ablation (group 1), 24 received antiarrhythmic therapy (group 2), 38 received no drugs or remained on drug therapy for only few months (group 3), 3 died and 10 were lost to follow-up. The frequency of symptoms at the baseline was higher in group 1 than in groups 2 and 3 (7.8+/-3.7, 3.5+/-2.3, 2.3+/-1.9 episodes/month, respectively; p<0.02 in group 1 vs. group 3). At the end of the follow-up 18/18 (100%) of group 1, 14/23 (61%) of group 2 and 17/38 of group 3 (44.7%) reported being asymptomatic for the previous 3 years. Group 3 patients who became asymptomatic had a shorter duration of symptoms before enrolment (3.7+/-1.5 vs. 7.1+/-3.6 years, p<0.05) and a shorter mean length of the tachycardia episodes (3.8+/-2.4 vs. 42.6+/-17.8 min, p<0.02) than patients from the same group who remained symptomatic. CONCLUSIONS: The main result of this study is that during a long-term follow-up a considerable number of untreated patients with AVNRT become asymptomatic. This finding should be considered for choosing treatment modality and for calculating healthcare costs of ablation vs. medical therapy.

Outcome of symptomatic patients undergoing extracardiac Fontan conversion and cryoablation.

OBJECTIVE: We review our experience with Fontan conversion and cryoablation in patients with an atriopulmonary Fontan in low cardiac output from arrhythmia or venous obstruction, including 2 patients with protein-losing enteropathy. METHODS: Ten patients (mean age 21.1 +/- 7.0 years) underwent extracardiac Fontan conversion, cryoablation, and pacemaker placement between November 1999 and April 2002 (13.1 +/- 4.1 years after the original atriopulmonary connection). Eight patients were in New York Heart Association class III and 2 were in New York Heart Association class IV. Nine patients had clinically important intra-atrial reentry tachycardia refractory to medical therapy. RESULTS: Follow-up was between 3.1 and 32.6 months (16.8 +/- 9). One death occurred at 7 days after surgery due to sepsis and multisystem organ failure. The second death occurred at 48 days from complications of protein-losing enteropathy. The second patient with protein-losing enteropathy had improved New York Heart Association classification, cessation of albumin transfusions, and a normal stool alpha antitrypsin level (down from 4.1 mg/g preoperatively). Five patients improved to New York Heart Association class I and 3 patients to New York Heart Association class II. Sustained arrhythmias could not be induced in any patient. Seven patients are on no antiarrhythmics. One patient had recurrence of intra-atrial reentrant tachycardia 11 months postoperatively, which required electrical cardioversion; this patient's symptoms are currently well controlled on 1 medication. CONCLUSION: Extracardiac Fontan, cryoablation, and pacemaker placement reduced atrial arrhythmias and improved New York Heart Association classification in all surviving patients. In selected patients, this operation offers improvement in clinical outcome and is an alternative to transplantation. Protein-losing enteropathy may not be a contraindication to performing Fontan conversion with cryoablation.

Location of acutely successful radiofrequency catheter ablation of intraatrial reentrant tachycardia in patients with congenital heart disease.

Intraatrial reentrant tachycardia (IART) is common after surgery for congenital heart disease (CHD). Radiofrequency (RF) catheter ablation of IART targets anatomic areas critical to the maintenance of the arrhythmia circuit, areas that have not been well defined in this patient population. The purpose of this study was to determine the anatomic areas critical to IART circuits, defined by activation mapping and confirmed by an acutely successful RF ablation at the site. A total of 110 RF ablation procedures in 88 patients (median age 23.4 years, range 0.1 to 62.7) with CHD were reviewed. Patients were grouped according to surgical intervention: Mustard/Senning (n = 15), other biventricular repaired CHD (n = 24), Fontan (n = 43), and palliated CHD (n = 6). In first-time ablation procedures, > or = 1 IART circuits were acutely terminated in 80% of Mustard/Senning, 71% of repaired CHD, and 72% of Fontan (p = NS). The palliated CHD group underwent 1 of 6 successful procedures (17%), and this patient was excluded. The locations of acutely successful RF applications in Mustard/Senning patients (n = 14 sites) were at the tricuspid valve isthmus (57%) and at the lateral right atrial wall (43%). In patients with repaired CHD (n = 18 sites), successful RF sites were at the isthmus (67%) and the lateral (22%) and anterior (11%) right atria. In the Fontan group (n = 40 sites), successful RF sites included the lateral right atrial wall (53%), the anterior right atrium (25%), the isthmus area (15%), and the atrial septum (7%). Location of success was statistically different for the Fontan group (p = .002). In conclusion, the tricuspid valve isthmus is a critical area for ablation of IART during the Mustard/ Senning procedure and in patients with repaired CHD. IART circuits in Fontan patients are anatomically distinct, with the lateral right atrial wall being the more common area for successful RF applications. This information may guide RF and/or surgical ablation procedures in patients with CHD and IART.

The surgical management of atrial fibrillation.

Atrial fibrillation is the most common dysrhythmia encountered in clinical practice. For some patients, satisfactory rate control is not possible by pharmacologic means. This led us to develop a surgical approach to its cure, which in turn has led to a deeper understanding of the electrophysiologic basis of atrial fibrillation and to the development of a surgical procedure that is highly effective in restoring sinus rhythm with an acceptable mortality and morbidity. We review these findings as well as the clinical results obtained with the Maze procedure.

[Problems with anti-arrhythmia therapy in atrial fibrillation]. / Probleme der antiarrhythmischen Therapie bei Vorhofflimmern.

The prevalence of atrial fibrillation increases with age, with rates of 2-5% among people over the age of 60 years. Patients may be highly symptomatic or may suffer from hemodynamic compromise or thromboembolic complications. However, antiarrhythmic drug treatment implies problems like the choice of the suitable drug, the individual benefit/risk profile, and alternative treatment strategies. Experimental and clinical data support the concept that atrial fibrillation in the clinical setting in most cases is due to multiple reentrant wavelets. A critical number of three to six simultaneously circulating reentrant wavelets seems to be necessary for the maintenance of atrial fibrillation. Consequently, antiarrhythmic drugs may terminate or prevent atrial fibrillation by prolonging the refractory period or slowing conduction velocity, thereby leading to conduction block. In clinical practice, antiarrhythmic therapy may act by slowing of the ventricular rate due to depression of atrioventricular nodal conduction or by termination and/or prevention of atrial fibrillation. Digitalis is commonly used for the control of the ventricular rate. Betablocking drugs and verapamil are effective in this respect during exercise performance. For antiarrhythmic conversion and prophylaxis of recurrences of atrial fibrillation, class Ia (e.g., quinidine), Ic (e.g., flecainide and propafenone), and class III (e.g., amiodarone and sotalol) drugs of the Vaughan Williams classification are useful. Presently, no general concept exists whether medical or electrical cardioversion should be used as a first line approach for termination of atrial fibrillation. In the individual patient with atrial fibrillation, the potential benefit of restoring sinus rhythm must be weighed against the morbidity and mortality of the arrhythmia and the morbidity and mortality of the antiarrhythmic agents used.(ABSTRACT TRUNCATED AT 250 WORDS)

[Long-term follow-up of patients after interruption of the atrioventricular conduction by electrode catheter and DC shock: experiences with 100 patients]. / Langzeitverlauf von Patienten nach Unterbrechung der atrioventrikulären Uberleitung durch Elektrodenkatheter und DC-Schock: Erfahrungen bei 100 Patienten.

Long-term follow-up (44 +/- 21 months) was studied in 100 patients (pts) (mean age 56 +/- 12 years) who underwent direct current ablation because of drug-resistant supraventricular arrhythmias. In 85 pts (85%) complete atrioventricular (AV) block was initially achieved. During the follow-up period, AV conduction resumed in 15 pts (15%). Thirteen pts underwent another ablation session and complete AV block was achieved in 11/13 pts (85%). After catheter ablation complete AV-block was achieved in 96 pts and the remaining four pts had second-degree AV-block. Complications like pericardial effusion, arterial hypotension or ventricular arrhythmias occurred in 18 pts. Total mortality was 13% (13 pts): one patient died suddenly, and seven pts died from cardiac causes (heart failure in six pts, reinfarction in one patient). Transcatheter direct-current ablation is an effective method to interrupt AV conduction and to treat patients with drug-resistant supraventricular arrhythmias. Although there is a small risk of severe complications, this procedure should be reserved for pts with supraventricular arrhythmias who do not respond to conventional drug treatment.