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Despite considerable basic research into the mechanisms of atrial fibrillation (AF), not much progress has been made in the prognosis of patients with AF. With the exception of anticoagulant therapy, current treatments for AF still do not improve major cardiovascular outcomes. This may be due partly to the diverse aetiology of AF with increasingly more factors found to contribute to the arrhythmia. In addition, a strong increase has been seen in the technological complexity of the methods used to quantify the main pathophysiological alterations underlying the initiation and progression of AF. Because of the lack of standardization of the technological approaches currently used, the perception of basic mechanisms of AF varies widely in the scientific community. Areas of debate include the role of Ca(2+) -handling alterations associated with AF, the contribution and noninvasive assessment of the degree of atrial fibrosis, and the best techniques to identify electrophysiological drivers of AF. In this review, we will summarize the state of the art of these controversial topics and describe the diverse approaches to investigating and the scientific opinions on leading AF mechanisms. Finally, we will highlight the need for transparency in scientific reporting and standardization of terminology, assumptions, algorithms and experimental conditions used for the development of better AF therapies. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Intraoperative radiofrequency (RF) ablation is an effective treatment of atrial fibrillation (AF). However, secondary arrhythmias late after ablation may complicate the patient's course. We report on the incidence, mechanisms, and treatment of gap-related atrial flutter and other secondary arrhythmias during long-term follow-up. METHODS AND RESULTS: In 129 patients who underwent intraoperative RF ablation with placement of left atrial linear lesions using minimally invasive surgical techniques, secondary arrhythmias were analyzed during long-term follow-up (20 +/- 6 months). Transient atrial arrhythmias during the first 3 postoperative months were excluded. In 8 (6.2%) of 129 patients, sustained stable secondary arrhythmias were documented. Left atrial, gap-related atrial flutter was observed in 4 patients (3.1%). The flutter was treated by percutaneous RF ablation in 3 patients (2.3%) and with drugs in 1 patient (0.8%). In 2 patients (1.6%), right atrial isthmus-dependent atrial flutter occurred and was treated successfully by percutaneous RF ablation. In 2 patients (1.6%), ectopic right atrial tachycardias occurred and were treated with percutaneous RF ablation. CONCLUSION: Late after intraoperative RF ablation of atrial fibrillation, three types of stable secondary arrhythmias were observed in 6% of patients: left atrial gap-related atrial flutter, right atrial isthmus-dependent atrial flutter, and ectopic atrial tachycardia. Gaps after intraoperative RF ablation due to noncontinuous or nontransmural linear lesions may lead to stable left atrial macroreentrant tachycardias, requiring new interventional therapy. [ABSTRACT FROM AUTHOR]

Aims We describe a new strategic stepwise mapping approach for fast and accurate identification and ablation of ectopic atrial foci using an electroanatomic mapping system.Methods and Results Mapping procedures started with the acquisition of four points at the superior/septal part of the tricuspid annulus. According to this activation sequence, maps were continued towards the right atrial free wall if relatively early activation was shown at the superior part of the initial map or towards the triangle of Koch and, if necessary, to the left atrium, in cases of relatively early activation at the septum. High density mapping and detailed electrogram analysis only of the target area allowed identification and ablation of 34 foci in 30 of the 32 studied consecutive patients. A small number of mapping points were sufficient within a procedure time of 90±41min for right 148±68min and for left sided foci and a total fluoroscopy time of 9·6±7·2min and 24·8±16·4min respectively. Sixteen foci were located at the right free wall, eight at the left free wall, and 10 at the right or left side of the septum.Conclusion Strategical electroanatomical mapping with fast identification of the area of tachycardia origin and high density mapping only of this target area allowed fast and successful localization and ablation of right and left free wall and septal ectopic atrial foci. Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved. [ABSTRACT FROM PUBLISHER]

Objectives This study is designed to examine the immediate and short-term outcomes of patients who have undergone slow pathway ablation/modification for atrioventricular nodal reentrant tachycardia.Background Targeting the slow pathway has emerged as the superior form of treatment for atrioventricular nodal reentrant tachycardia. This technique has been found effective and is associated with a low complication rate. However, little is known of the long-term outcome of patients undergoing this procedure.Methods Over a 40-month period the slow pathway was targeted in 379 consecutive patients with proven atrioventricular nodal reentrant tachycardia. The case records of all patients were examined. Accurate follow-up data is available in 96% of patients a mean of 20·6 months after the procedure.Results The initial success rate was 97%. The incidence of complete heart block was 0·8% and the mean fluoroscopy duration was 27·3min. The recurrence rate was 6·9%. Age, number of pulses and fluoroscopy time were positively associated with either initial failure or recurrence. A total of 11·3% of patients were still taking antiarryhthmic medication at follow-up.Conclusions Targeting the slow pathway is an effective form of treatment for atrioventricular nodal reentrant tachycardia. The technique has a high initial success rate, a low complication rate and a low recurrence rate at long-term follow-up. Slow pathway modification is associated with similar success rates and recurrence rates as slow pathway ablation and may confer theoretical long-term benefits. [ABSTRACT FROM PUBLISHER]

Provides information about several tutorials on technology and health care. Discussion on Remote-Data Entry; Description of a tutorial on the design of dynamic interactive medical Web applications; Utilization of Internet technology for human genetics research.

Intraoperative Ablation of Atrial Fibrillation. Introduction: The percutaneous approach to radiofrequency (RE) catheter ablation for curative treatment of atrial fibrillation (AF) is an investigational technique, and the optimal composition of lesion lines is unknown. We tested an intraoperative RE ablation concept with elimination of left atrial anatomic 'anchor' reentrant circuits. Methods and Results: In 12 patients with an indication for valve surgery and chronic AF, a right atrial-transseptal approach was chosen for access to the left atrium. AF had been present for 4.3 ± 3.9 years; the left atria measured 56 ± 7 mm. Under direct vision, contiguous lesion lines were placed endocardially with temperature-guided RF energy applications for treatment of AF with a specially designed probe. The lesion lines were placed between the mitral annulus and the left lower pulmonary vein, further to the left upper pulmonary vein, from there to the right upper pulmonary vein, and finally to the right lower pulmonary vein. The antiarrhythmic ablation procedure lasted 19 ± 4 minutes. One patient died postoperatively of low cardiac output. During follow-up of 11 ± 6 months, chronic AF was ablated successfully in 9 of 11 patients (82%). Six patients were in stable sinus rhythm or intermittent pacemaker rhythm, and three patients were in sinus rhythm with Intermittent atypical atrial flutter. Conclusions: Intraoperative RF energy application for induction of contiguous lesion lines is feasible. Elimination of anatomically defined 'anchor' reentrant circuits within the left atrium prevented chronic AF in > 80% of the patients treated. Intraoperative validation of lesion line concepts for curative treatment of AF may be transferred to percutaneous ablation techniques. [ABSTRACT FROM AUTHOR]

Aims The purpose of this study was to assess the acute and long-term success of accessory pathway ablation in a single large-volume centre, concentrating on long-term recurrences and the clinical use of antiarrhythmic drugs.Methods and Results A total of 519 consecutive patients (mean age 40±14 years) underwent radiofrequency ablation of manifest or concealed accessory pathways. The patients were seen in the hospital or by the referring physician at 6 and 12 months. Long-term follow-up information was obtained by questionnaire. Pathway conduction was abolished in 476 cases (91·7%). ‘Redo’ procedures, due to recurrence, were performed in 38 patients (7·3%) and were successful in 30 (78·9%). Follow-up data were obtained from 454 patients (87·5%) with a follow-up duration of 22·6±12·4 months. Among the 398 patients with successful ablations who responded to the questionnaire, 340 (85·4%) were asymptomatic with only 10·6% taking antiarrhythmic drugs. An additional 20 patients (5·0%) had symptoms suspicious of recurrence. In total, 66 out of 398 successfully treated patients (16·6%) were taking antiarrhythmic drugs. Twenty-three out of 56 (41·1%) patients with failed ablations were asymptomatic, 12 of whom (21·4% of patients with failed ablations) had not been administered antiarrhythmic drugs. In the total group of 454 patients with ablation attempts and available follow-up data, 99 (21·8%) were still taking antiarrhythmic drugs during follow-up.Conclusions Patients with successful ablation of accessory pathways show excellent long-term results. However, 17% of successfully treated patients were still taking antiarrhythmic drugs during the period of long-term follow-up. On the other hand, 21% of patients with failed ablations were symptom-free without antiarrhythmic drugs. On an intention-to-treat basis, 22% of the patients with ablation attempts were still taking antiarrhythmic drugs during follow-up. [ABSTRACT FROM PUBLISHER]

Aims Anatomical and electrogram-guided techniques have been used separately for slow pathway ablation in atrioventricular nodal reentrant tachycardia. The aims of the present study were to analyse electrogram characteristics of target sites and biophysical parameters using a combined anatomical and electrogram-guided technique for temperature-controlled radiofrequency catheter ablation of the slow pathway. Methods and results Using a temperature-controlled (pre-selected 60 °C) catheter system, 53 patients with atrioventricular nodal reentrant tachycardia underwent slow pathway radiofrequency ablation. Mapping was started posteroseptally near the coronary sinus ostium and continued towards the midseptal area if needed. The longest and latest atrial electrograms with an atrioventricular ratio of ≤0·5 were targeted. After a median of two pulses (mean 2·36 ± 1·33), atrioventricular nodal reentrant tachycardia was rendered non-inducible in all patients without complications. Successful sites had longer atrial electrograms (78·8 ± 9·8 vs 67·6 ± 13·3 ms, P<0·003) and larger ventricular electrogram amplitudes (92·4 ± 51·2 vs 63·1 ± 28·8 mV, P<0·05) than the failed sites, but had a similar atrioventricular ratio, P-A interval and atrial electrogram amplitude. Overall, an atrial electrogram duration of ≥70 ms was associated with effective radiofrequency delivery, with 86% sensitivity and 62% specificity. The achieved temperature maximum was 62·3 ± 9·8 °C at successful and 58·8 ± 9·0 °C at unsuccessful sites (ns). There was no significant difference between successful and unsuccessful applications with respect to power output, impedance and total delivery energy. During a pre-discharge study, three patients with inducible atrioventricular nodal reentrant tachycardia underwent a repeat ablation. During 12·3 ± 2·5 (6–15) months of follow-up, three others had a clinical recurrence of atrioventricular nodal reentrant tachycardia. Conclusions The combined approach for slow pathway ablation is highly effective, requiring a low number of radiofrequency pulses. Long atrial activation time seems to be the most powerful predictor of success. Similar catheter tip temperature levels during successful and unsuccessful radiofrequency applications indicate that suboptimal selection of target sites rather than ineffective heating due to poor catheter tissue coupling is responsible for unsuccessful energy delivery. [ABSTRACT FROM PUBLISHER]

Objectives The primary objectives of this study were to assess the feasibility of temperature-controlled radiofrequency catheter ablation of left and right sided manifest accessory pathways in patients with Wolff-Parkinson-White syndrome and to gain more insights into biophysical aspects of temperature-controlled catheter ablation in humans. Background The electrode-tissue interface temperature and other biophysical parameters are among important variables determining the efficacy and safety of radiofrequency ablation of accessory pathways. Experimental studies have shown that radiofrequency-induced tissue necrosis can be accurately predicted by monitoring of catheter tip temperature. Methods 38 consecutive patients (14 f, 24 m; aged 42 ± 12 years) with anterograde conducting accessory pathways (left sided: n=22; right sided: n=l6) underwent temperature-controlled radiofrequency ablation (HAT 200S, Dr Osypka, Germany). The electrode temperature was monitored via a thermistor embedded into a 4 mm catheter tip. Power output was adjusted automatically during energy delivery in a closed loop system (preselected temp.: 70·1 ± 5·8°C). Results Accessory pathway conduction was successfully abolished in all patients after the delivery of 2·3 ± 2·1 radiofrequency pulses (range: 1–9, median: 2). Interruption of the accessory pathway as evidenced by loss of preexcita tion occurred after 5·9 ± 5·4 s. At the time of the interruption of the accessory pathway the catheter tip temperature measured 54·2 ± 11· 2 ° C in patients with left and 44·9 ± 5·0° C in patients with right sided accessory pathways, respectively (P<0·008). Higher temperature levels during left sided applications did not shorten the time it took for the effect to appear (left sided accessory pathway: 7· 5 ± 6· 3 s, right sided accessory pathway: 3· 7 ± 2· 9 s; ns). The catheter tip temperature was significantly higher during left compared to right sided applications after 5 (52· 1 ± 3· 1 °C vs 47· 2 ± 4· 3 ° C) and 10s (61· 5 ± 6· 2 ° C vs 52· 7 ± 4· 2° C) following initiation of the impulse (P<0· 005). Power output and delivered energy did not differ significantly at the time of accessory pathway abolition. Peak values of delivered power (45· 1 ± 10· 9 W vs 41· 3 ± 10· 6W; P< 0· 05) and total delivered energy (2452 ± 1335 J vs 1392 ± 762 J; P<0· 02) were significantly higher in the group of right sided pathways compared to left sided applications. The peak temperature measured 77· 1 ± 13 °C during effec tive and 69· 9 ± 14 °C during ineffective energy applications (P<0· 05). The time it took for the effect to appear was significantly longer in transiently effective pulses (10· 4 ± 7· 2 s) compared to permanently effective applications (5· 9 ± 5· 4 s; P<0· 02). Despite temperature control, an abrupt rise in impedance was observed in 10 of 89 (11%) energy applications. No procedure-related complications occurred. Conclusions Temperature-controlled radiofrequency ablation of manifest accessory pathways is highly effective and safe. The temperature response is faster and signficantly higher in left-sided energy applications compared to right-sided pulses. Peak temperature levels measured at the electrode tip are significantly higher during effective than ineffective pulses. Sudden rises in impedance are not com pletely prevented during temperature-controlled radiofrequency ablation of accessory pathway, although no procedure-related complications were noted in this patient cohort. [ABSTRACT FROM PUBLISHER]

Up to now there have been no descriptions in the literature of endocardial catheter mapping and successful radiofrequency catheter ablation of the right sided accessory pathway during sustained atrial fibrillation. We attempted ablation of a right posterolateral and a right lateral accessory pathway during sustained atrial fibrillation with rapid anterograde conduction over the accessory pathway in two patients with Wolff-Parkinson-White syndrome. In both patients (aged 47 and 52 years), sustained atrial fibrillation occurred during the electrophysiological study to assess accessory pathway conduction properties. The mean ventricular rate during atrial fibrillation was 180 and 170beats. min, respectively. Both patients were successfully ablated with a single radiofrequency impulse. At the successful ablation sites, a potential of the accessory pathway was consistently recorded preceding the onset of preexcitation in the surface electrogram, by 25 ms in patient 1 and 30 ms in patient 2. The unipolar electro-gram recorded from the ablation catheter showed a QS morphology and the accessory pathway potential preceded the intrinsic deflection by 10 ms in both patients. Onset of the ventricular electrogram (patient 1: − θ20 mθ patient 2: − θ15 ms) and its activation time (patient 1: − θ15 mθ patient 2: ±5 ms) in relation to the onset of preexcitation in the surface electrocardiogram also indicated the close proximity of the ablation catheter to the accessory pathway. Preexcitation disappeared within 2 s after energy application in both patients. Thus, radiofrequency catheter ablation of right sided accessory pathways during sustained atrial fibrillation is feasible and may obviate the need for medical or electrical cardioversion. Appropriate target sites can be identified by the presence of an accessory pathway potential, early onset and activation of the local ventricular electrogram, and the QS morphology of the unipolar electrogram. [ABSTRACT FROM PUBLISHER]

Ventricular arrhythmias are a frequent finding in patients with heart failure, and heart failure is a major underlying condition which is correlated to sudden death. Therefore, both sudden death and death from progression of heart failure strongly overlap. Besides long-term ECG recording, newer diagnostic techniques have been developed. The prognostic significance of the signal-averaged ECG in patients with advanced left ventricular dysfunction in the presence of coronary artery disease has been demonstrated; however, in patients with dilated cardiomyopathy, signal-averaging for detection of late potentials has not yet been clearly established as a useful diagnostic tooL Furthermore, heart period variability has been shown to correlate to overall mortality but not to a specific mechanism. Finally, programmed ventricular stimulation, though useful in patients with left ventriculor dysfunction and/or heart failure in the setting of coronary artery disease, is of questionable significance in patients with dilated cardiomyopathy.With increasing degreees of left ventricular dysfunction, the efficacy of antiarrhythmic drugs decreases On the other hand, with increasing degrees of heart failure, antiarrhythmic drugs demonstrate a greater negative inotropic effect, more frequent proarrhythmic effects, and more frequent bradyarrhythmias Currently, severai ongoing amiodarone trials are msessing different approaches of antiarrhythmic treatment in patients with heart failure. The European Myocardial Infarction Amiodarone Trial (EMIAT) addresses the role of amiodarone in patients after myocardial infarction with an ejection fraction of 40% or less irrespective of spontaneow ventricular arrhythmias; the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial (CAMIAT) includes patients after myocardial infection with 10 or more VPBs per hour or one or more runs of ventricular tachycardia on 24-h ECG monitoring; and the US-Veteran's Administration Study in patients with congestive heart failure (US-VA) included patients with a history of congestive heart failure and reduced ventricular function Additionally, the Survival with Oral d-Sotalol (SWORD) Trial included patients after myocardial infarction with a low ejection fraction irrespective of spontaneous ventricular arrhythmias. Recently, the implantable cardioverter-defirillator (ICD) has gained widespread acceptance as a first line tratment modality for patients with documented life-threatening ventricular tachyarrhythmias The ability of ICD devices to terminate ventricular tachycardia or fibrillation has been clearly demonstrated. However, whether overall cardiac mortality may also be significantly improved especially in patients with severely impaired left ventricularfinction is less clear. On the other hand, considering the high risk ofpatients with moderate to severe heart failure for sudden cardiac death, information on the impact of prophylactic implantation of ICD devices in high risk patients would be desirable. Recently, the Cardiomyopathy Trial was started, assessing the prophylactic use of ICD systems in patients with dilated cardiomyopathy, heart failure of NYHA class II or III, and absence of symptomatic ventricular arrhythmiasThe role of ventricular arrhythmias and sudden death in patients with heart failure is still an enigma. Currently, we should treat heart failure but present clata do not support antiarrhythmic drug treatment of asymptomatic complex arrhythmias detected on Holter monitoring. In patients with documented sustained ventricular tachycardia or fibrillation or in patients who have been resuscitated from sudden cardiac death, the subcutaneously implantable ICD will probably establish itself as a first lrne treatment modulity in the near future. However, given the ... [ABSTRACT FROM PUBLISHER]

Background Due to the investigative nature of AF catheter ablation, currently only highly symptomatic patients are treated. Remarkable success rates have been reported repeatedly. However, the follow up strategies measuring that outcome are largely based on symptomaticity. Therefore the present study aimed on analyzing the perception of AF in 114 pts. before and after a left atrial catheter ablation using the CARTO System. Methods A digital 7-d-ECG was recorded prior to ablation, right after ablation, after 3 months, after 6 months and after 12 months. During the 7-d-ECG the pts. hourly registered quality and duration of any symptoms in a certain patient's log. Palpitation, dyspnoea, dizziness and chest pain were taken as surrogates of AF. Subsequently the amount of time with symptomatic AF, asymptomatic (ASYM) AF, symptomatic SR and ASYM SR was measured. Additionally the individual AF episode was classified as either symptomatic or ASYM. Results For more than 75000 hours of ECG recording symptoms and rhythm were correlated. Prior ablation 54% of the time in AF and 22% of the AF episodes were ASYM. After ablation the proportion of ASYM AF episodes increased from 22% to 53% of all AF episodes. Watching the individual patient ASYM AF was common in 65% of all pts. with AF before and after catheter ablation. Nevertheless, the percentage of pts. with only ASYM AF during the 7-d-ECG increased from 10% prior ablation to 36% 6 months after ablation. Conclusions Pts. with highly symptomatic AF also exhibit a substantial amount of ASYM arrhythmia (54% of AF time, 22% of AF episodes). After ablation the amount of ASYM AF increased, with half of the episodes being ASYM. Furthermore, 36% of the pts. with AF recurrences at the 6 months follow up were completely ASYM during that 7-d-ECG. [ABSTRACT FROM PUBLISHER]

Background Cardiac resynchronization therapy (CRT) is an established therapy. There are two techniques to implant the left ventricular (LV) lead i.e. transvenous implantation (TI) via the coronary sinus and surgical implantation using left lateral minithoracotomy (LLM). This study was designed to compare the procedures, treatment results as well as complications. Methods In this study we included 81 patients (pat.). All pat. received right atrial and ventricular lead using established TI techniques. The LV lead was positioned via the coronary sinus (59 pat.) or via LLM epimyocardially (22 pat.). Baseline evaluation included assessment of NYHA functional class, electrocardiogram and echocardiography. These measurements were repeated during the follow-ups (FU). Additionally data on the procedure as well as perioperative data was collected. Results Both groups showed significant improvement in NYHA (3,2±0,4 to 2,0±0,6, p<0,001) as well as in the LV-ejection fraction by 22 percent (p<0,001). The TI group had an average implantation time of 134±46,8 minutes. Pat. with LLM had an average operation time of 116,6±48,7 minutes. Intensive care unit (ICU) treatment after implantation were 1,3±1,6 days (TI) versus 3,4±3 days in the epimyocardial group (p<0,001). Postoperative stay was significantly longer in the epimyocardial group (9,4±6,4 days) compared to 6,1±3,1 days (p<0.001) (TI). No deaths occurred intra- or perioperative in the hospital. No significant differences were found during further FU. Conclusion The transvenous positioning of the lead does have prolonged procedure time, longer x-ray time and higher incidence of reinterventions due to lead dislocations compaired to epimyocardial implantation. However, the results of this study suggest that pat. who are eligible for CRT should receive their LV lead as a primary procedure transvenously due to less trauma, local anesthesia, less ICU treatment, less days in hospital and consequentially lower costs for an implantation. To receive comparatively results a prospective randomized study is necessary. [ABSTRACT FROM PUBLISHER]