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A variety of strategies have been proposed to avoid the risks of pulmonary vein ablation for atrial fibrillation. The fall of impedance during radiofrequency catheter ablation can be used as a real time measure of tissue heating. The aim of this study was to analyze the impedance fall during ostial pulmonary vein ablation and to evaluate whether adjusting power to the fall of impedance may contribute to a reduction of the risk of complications.Analysis of biophysical parameters of ablation and determination of ostial diameters during follow-up were performed in 70 patients undergoing impedance-guided segmental ostial pulmonary vein ablation. Repeat radiographic angiography, local electrograms, and baseline impedance were the criteria to define the position of the 4-mm electrode tip at atrial sites or inside the proximal pulmonary veins.Energy application inside the proximal pulmonary veins led to an increased impedance fall inside the first 5-10 mm of the pulmonary veins (1.1 +/- 0.5 Omega/W) as compared to ablation at atrial sites (0.7 +/- 0.3 Omega/W) (P0.01). The analysis of temperature and impedance fall during ostial ablation demonstrated an increased impedance fall with heating at sites inside the proximal pulmonary veins (1.5 +/- 0.6 Omega/ degrees C) as compared to atrial sites (1.2 +/- 0.5 Omega/ degrees C) (P0.001). The regression lines analyzing these correlations indicated that adjusting power to a maximum impedance fall of 20 Omega would limit heating at pulmonary venous sites to lower temperatures (average maximum temperature: 48 degrees C) than at atrial sites (average maximum temperature: 63 degrees C). The ablation strategy used for segmental ostial ablation in 70 patients, which involved power limitation to a maximum impedance fall of 20 Omega, allowed isolation of 89% of targeted pulmonary veins with a low rate of impedance rises (0.3% of applications). No pulmonary vein stenoses30% were detected by follow-up computed tomography analysis.An increased impedance fall as the result of heating during ostial ablation was found inside the proximal pulmonary veins as compared to atrial sites. Adjusting power to the fall of impedance during segmental ostial pulmonary vein ablation contributes to the prevention of overheating inside the pulmonary veins and may lower the risk of coagulum formation and pulmonary vein stenosis.

Contains fulltext : 50502.pdf (Publisher’s version ) (Closed access) This document by the Study Group on Sports Cardiology of the European Society of Cardiology extends on previous recommendations for sports participation for competitive athletes by also incorporating guidelines for those who want to perform recreational physical activity. For different supraventricular arrhythmias and arrhythmogenic conditions, a description of the relationship between the condition and physical activity is given, stressing how arrhythmias can be influenced by exertion or can be a reflection of the (patho)physiological cardiac adaptation to sports participation itself. The following topics are covered in this text: sinus bradycardia; atrioventricular nodal conduction disturbances; pacemakers; atrial premature beats; paroxysmal supraventricular tachycardia without pre-excitation; pre-excitation, asymptomatic or with associated arrhythmias (i.e. Wolff-Parkinson-White syndrome); atrial fibrillation; and atrial flutter. A related document discusses ventricular arrhythmias, channelopathies and implantable cardioverter defibrillators.

Mit zunehmendem Verstandnis der pathophysiologischen Grundlagen von Arrhythmien gewinnen auch Erkenntnisse zu geschlechtsspezifischen Unterschieden an Bedeutung, die einen Einfluss auf das akute und langfristige Management von Herzrhythmusstorungen haben konnen. Neben bereits gut bekannten elektrokardiographischen Unterschieden wie einer hoheren Ruhefrequenz und einer langeren QTc-Zeit, zeigen sich auch Unterschiede in der klinischen Inzidenz und Manifestation verschiedener Arrhythmien. Dies betrifft bestimmte Formen paroxysmaler supraventrikularer Tachykardien wie die AV-Knoten-Reentrytachykardie und das WPW-Syndrom, ebenso wie Vorhofflimmern, und Kammertachykardien. Insbesondere haben Frauen auch eine deutlich hohere Pravalenz sowohl angeborener als auch erworbener Formen des long-QT-Syndroms.

In patients with implantable cardioverter-defibrillators (ICDs), 25 to 45% of tachyarrhythmia episodes were initiated by short-long-short RR intervals.The prospective multi-center PREVENT study randomized patients implanted with ICDs capable of atrioventricular pacing, in order to compare-using a cross-over design with two 3-month treatment periods-the benefits of 'rate smoothing' (RS) as a 'pause-prevention algorithm' for the prevention of ventricular tachyarrhythmias.Follow-up included 219 patients with implanted ICDs, of whom 153 were eligible for analysis as per protocol. Fifty-seven of these patients (38%) had documented episodes of ventricular tachyarrhythmias during the six months follow-up. The total number of sustained ventricular tachyarrhythmia episodes was reduced from 358 with RS Off to 145 with RS On. RS was effective in reducing the number of short-long-short induced sustained ventricular episodes from 100 with RS Off to 40 with RS On. The Wilcoxon-Mann-Whitney point estimator equals 0.66 with a 95% confidence interval from 0.51 to 0.82 (relevant superiority; corresponding p = 0.039). There were no proarrhythmic effects due to rate smoothing within the scope of this study.'Rate smoothing' significantly reduced sustained ventricular tachyarrhythmias in ICD patients. There is a relevant superiority of the treatment during the early six months of follow-up.

Arrhythmogenic right ventricular dysplasia is a structural heart disease characterized by fibrofatty degeneration of right ventricular myocardium and arrhythmias of right ventricular origin. The aim of this study was to characterize endocardial right ventricular activation by electroanatomic mapping as a guide for catheter ablation in patients with arrhythmogenic right ventricular dysplasia. Electroanatomic mapping and entrainment procedures were performed in 5 patients with arrhythmogenic right ventricular dysplasia. Endocardial mapping during ventricular tachycardia demonstrated a focal activation pattern with radial spreading of activation from a site of earliest ventricular activation in all directions. Right ventricular activation time (127 ± 34 ms) was markedly shorter than tachycardia cycle length (415 ± 92 ms). The site of earliest ventricular activation was found in an aneurysmal outflow tract (n = 2), at the border of aneurysms near the tricuspid annulus (n = 2), and at the apex of the right ventricle (n = 1). Entrainment mapping criteria of these areas of earliest endocardial activity were consistent with exit sites of a reentrant circuit in an area of abnormal myocardium. Fractionated potentials were found 61 ± 29 ms before the onset of the QRS complex at these sites. Catheter ablation rendered the “clinical“ ventricular tachycardia noninducible in four patients but “nonclinical” faster ventricular tachycardias were inducible in three patients. During the follow-up of 7 ± 3 months after ablation, the frequency of therapies in 4 patients with an implantable cardioverter defibrillator decreased from 49 ± 61 episodes per month before ablation, to 0.3 ± 0.5 episodes per month after ablation (P < 0.05). Electroanatomic mapping during ventricular tachycardia facilitates localization of exit sites in relation to aneurysms in diseased right ventricle and may guide catheter ablation in patients with arrhythmogenic right ventricular dysplasia. (PACE 2003; 26:1308–1316)

Implantable Defibrillator Lead Failure. Introduction: Patients with implantable cardioverter defibrillators (ICD) critically depend on correct functioning of their system. The aim of this study was to determine the incidence and clinical presentation of transvenous ICD lead failures during long-term follow-up. Methods and Results: The study group consisted of 261 consecutive patients who received Medtronic right ventricular polyurethane transvenous leads (models 6884, 6966, 6936) between 1990 and 1998 as part of an abdominal(n = 70)or pectoral(n = 191)ICD system. During mean follow-up of4.0 ± 2.6 years, 31 patients (12%) developed a lead-related sensing failure with oversensing of artifacts. All failures except two were compatible with an insulation defect and occurred late after ICD placement (6.0 ± 1.8 yearsafter implant). Lead survival decreased from 98% at 4-year follow-up to only 62% at 8-year follow-up. Lead survival was not related to patient age, sex, venous lead implantation route, or device implantation site. In 26 (87%) of 31 patients, a sensing defect resulted in inappropriate detection of ventricular fibrillation and subsequent delivery of3 ± 3(range 1–11) inappropriate shocks in 19 (61%) of 31 patients. Device interrogation showed artifacts classified as nonsustained ventricular tachycardia in 21 patients,40 ± 43 daysbefore clinically relevant failure of the system. One patient with a subclavian crush syndrome required resuscitation because of undersensing of true ventricular fibrillation. Conclusion: Transvenous polyurethane ICD leads showed a high rate of lead insulation failure late after implantation with frequent inappropriate shock deliveries. Close follow-up is mandatory in patients with these leads. Automated device control features with patient alert function integrated into new devices may contribute to early detection of lead failure.

Pulmonary vein bigeminy is the pair of a second, late and ectopic pulmonary vein potential following atrial far-field activation and a first passive pulmonary vein potential during sinus rhythm. The aim of this study was to determine the electrophysiological characteristics of pulmonary vein bigeminy and to evaluate its relevance as a trigger for paroxysmal atrial fibrillation.Pulmonary vein bigeminy was recorded in 8 of 45 patients (18%) who underwent mapping of pulmonary veins for ablation of focal atrial fibrillation. The premature ectopic pulmonary vein potentials were conducted to the atria in 5 patients and were not conducted (concealed bigeminy) in 3 patients. The coupling interval of the ectopic pulmonary vein potential to the preceding atrial signal during sinus rhythm was significantly longer in patients with conducted bigeminy (375 +/- 25 ms) than with concealed bigeminy (230 +/- 17 ms). The pulmonary vein bigeminy was driven by coronary sinus pacing with the pacing cycle length at lower stimulation rates and was suppressed by overdrive pacing. Coronary sinus pacing led to a separation of the first pulmonary vein potential from the atrial signal but the interval between the atrial signal and the second pulmonary vein potential remained unchanged. Focal ablation at the site of earliest ectopic pulmonary vein activity in 5 patients induced rapid repetitive firing before elimination of the pulmonary vein bigeminy. Ostial disconnection of the arrhythmogenic pulmonary vein in 3 patients was associated with elimination of the pulmonary vein bigeminy. During the follow-up of 9 +/- 5 months after ablation of the pulmonary vein bigeminy, 5 of the 8 patients (63%) were free of atrial fibrillation without antiarrhythmic medication.The response of pulmonary vein bigeminy to atrial pacing and ostial ablation suggests that pulmonary vein bigeminy depends on an intact electrophysiological breakthrough between the left atrium and the pulmonary vein. Ablation targeting the pulmonary vein bigeminy is a possible limited approach for this subgroup of patients with paroxysmal atrial fibrillation.

So far device sizing before TAVI is recommended by Echo measurements which are however known to be somehow inaccurate taking into acount the oval shape of the anulus and device undersizing is a major cause for paravalvular regurgitation. In the current study we therefore assessed the post

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with major complications. Ongoing research is focused on new pacing devices for alternative treatment of this disease. The objective of an AF registry is to store prospectively all relevant data covering clinical information, quality of life and device parameters and by this means provide a platform for long-term follow-up. For statistical analysis, categorical and numerical items are required, thus a high-granular data structure must be defined and implemented in the clinical setting. Facing the limits of formalization, we developed an XML-based documentation scheme consisting of 619 items in eight tables and implemented it with state-of-the-art Intranet technology. At present detailed information on 88 patients is recorded. The pacing device generates per patient and follow-up visit a file consisting of approximately 400-500 parameters provided on a floppy disk, which are transferred by means of a specific interface into the database. Success factors for integration of a complex research database into the routine workflow of a busy university hospital are interfaces between data sources to enable non-redundant data entry, intensive fine tuning by iterative software engineering and benefit for the clinical users in form of clinical reports and patient-specific summaries. Data quality must be assured by plausibility checks. To get an overview of this complex dataset we developed a dedicated visualization tool. Due to the high number of items a large patient collective must be recruited for statistical evaluation. Interinstitutional cooperation is required for a consensus on common minimal documentation schemes to enable pooling of data.

The aim of this study was to evaluate the clinical use of a new three-dimensional mapping system as a guide for catheter ablation of ectopic atrial tachycardia. A series of 42 consecutive patients with drug refractory ectopic atrial tachycardia was studied in a prospective observational trial with the electroanatomic mapping system CARTO. The arrhythmogenic focus was found in the right atrium in 30 patients and in the left atrium in 12 patients. The construction of a complete electroanatomic map of the right or left atrium was possible in 37 of 42 consecutive patients with ectopic atrial tachycardia. Mean activation time of the right atrium, including the proximal coronary sinus, was 94 +/- 25 ms for right atrial tachycardias; left atrial activation time during left atrial tachycardias was 86 +/- 17 ms. Average mapping time was 30 minutes for right atrial tachycardias and 22 minutes for left atrial tachycardias, allowing the collection of 86 +/- 50 and 65 +/- 28 catheter positions, respectively. The size of the area of earliest atrial activation calculated from the electroanatomic map amounted to 0.6 +/- 0.4 cm2 in right atrial tachycardias and 1.0 +/- 0.9 cm2 in left atrial tachycardias. In the right atrium the most common locations of the 33 arrhythmogenic foci in 30 patients were the high or mid-lateral right atrium (n = 10) and the inferoparaseptal region near the coronary sinus ostium (n = 7). Ectopic left atrial foci were most commonly located in an inferior position near the mitral annulus (n = 5) and in proximity to the ostium of the pulmonary veins (n = 4). Biatrial electroanatomic mapping allowed visualization of earliest right atrial activation during left atrial tachycardia at the high interatrial septum or near the coronary sinus ostium. Catheter ablation was successful in 85% of right atrial tachycardias and 82% of left atrial tachycardias. In patients with ectopic atrial tachycardia electroanatomic mapping is a safe and feasible technique that allows three-dimensional visualization of the automatic focus in a precise anatomic reconstruction of the atria. This novel mapping technology facilitates catheter ablation of complex ectopic atrial tachycardia.

Dual-implantable electronic device (IED) therapy is challenging since potential device interaction might occur resulting in inappropriate ICD therapy. A 57-year-old male was referred to our implantable cardioverter defibrillator …

Eine Tachykardie ist definiert als eine Herzfequenz von mehr als 100/min unabhangig von der Ursache. Diese Tachykardie kann im Sinusknoten, Vorhof, AV-Uberleitungsgewebe und in der Kammer entstehen. Als elektrophysiologische Entstehungsmechanismen mussen die fokale Impulsbildung und Kreiserregungen diskutiert werden.

Im Rahmen einer Storung der Sinusknotenfunktion konnen folgende Rhythmusstorungen auftreten (Ferrer 1968; Lown 1967): Sinusbradykardie (zeitweiser oder konstanter Frequenzabfall unter 50/min), SA-Blockierung, Sinusknotenstillstand, supraventrikulare Tachyarrhythmie in Form von Vorhoftachykardie, Vorhofflattern und Vorhofflimmern.

Rhythmusstorungen des Herzens werden in eine zu langsame (Bradykardie, 100/min) eingeteilt. Sie konnen daruber hinaus mit einer Anderung des normalen Erregungsablaufs im Herzen einhergehen (z. B. Reizbildung an anderer Stelle des Herzens als im Sinusknoten oder Erregungsleitungsstorung).

Die Pravalenz atrialer Tachykardien betragt 10–15 % bei Patienten mit regelmasigen anhaltenden supraventrikularen Tachykardien. Atriale Tachykardien sind haufig medikamentos therapierefraktar und die Anzahl von Patienten mit atrialen Tachykardien und einer Indikation fur eine Radiofrequenz-Katheterablation nimmt zu. Endokardiales Kathetermapping ist eine wichtige Voraussetzung fur das Verstandnis der Arrhythmiemechanismen und fur die moglichst genaue Lokalisierung der erfolgreichen Ablationsstelle (4, 7). Bei allen fokalen Tachykardien entspricht das arrhythmogene Substrat dem am fruhesten erregten Myokardbereich. Es kann sich aber als sehr schwierig und zeitaufwendig erweisen, die lokalen Aktivierungszeiten raumlich den anatomischen Strukturen zuzuordnen. Neben verschiedenen elektrophysiologischen Methoden des Aktivierungsmappings werden neue Mappingtechnologien verwendet, um die Lokalisierung des arrhythmogenen Substrats zu vereinfachen, so das selbst komplexe Tachykardien erfolgreich abladierbar werden. Das elektroanatomische Mapping mit dem CARTO-System setzt eine konventionelle elektrophysiologische Diagnostik voraus und erlaubt dann eine farbkodierte raumliche Zuordnung der atrialen Aktivierungszeiten. Wir untersuchten die Anwendbarkeit und Sicherheit dieser neuen elektromagnetischen Mapping- und Ablationstechnologie bei rechts und links (fokalen) atrialen Tachykardien.

Rhythmusstorungen des Herzens konnen eine Vielzahl von Symptomen verursachen, deretwegen der Patient den Arzt aufsucht. Die Beschwerden reichen von Palpitationen, unsystematischem Schwindel, Schwachegefuhl bis zu gravierenderen Beschwerden wie Auftreten von Angina pectoris, Dyspnoe, objektiven Zeichen der Links- und Rechtsherzinsuffizienz sowie Synkopen. Im schlimmsten Fall ist der plotzliche Herztod Ausdruck einer malignen Herzrhythmusstorung, die nur durch rechtzeitige Wiederbelebungsmasnahmen einschlieslich Defibrillation behoben werden kann.

A68-year-old man presented with an incessant supraventricular tachycardia 3 months after heart transplantation. A dual-chamber pacemaker had been implanted immediately after surgery for bradyarrhythmias. Electrophysiological study was performed with a multipolar halo catheter (20 electrode pairs) in the right atrium and bi- or quadripolar catheters in a high lateral, His, and coronary sinus ostium position of the right atrium (Figure⇓, top right). An atrial reentrant …

Aims This study aimed to clarify the safety and efficacy of selective fast pathway ablation in patients with atrioventricular nodal reentrant tachycardia and a prolonged PR interval during sinus rhythm. Such patients have been reported to have an increased incidence of complete atrioventricular block. Methods and Results In this study, the earliest retrograde atrial activation during atrioventricular nodal reentrant tachycardia and right ventricular stimulation was localized. Fast pathway ablation was then performed in five patients with the common form of atrioventricular nodal reentrant tachycardia and a prolonged PR interval. Three of the five patients had almost incessant atrioventricular nodal reentrant tachycardia. Radiofrequency catheter ablation induced a complete ventriculo-atrial block during right ventricular stimulation in four patients and a marked prolongation of ventriculo-atrial conduction during right ventricular stimulation in one. Non-inducibility of common atrioventricular nodal reentrant tachycardia with and without isoproterenol was achieved in all five patients. The PR interval increased from 254 ± 53 ms to 276 ± 48 ms and the atrio-His interval from 172 ± 46 ms to 192 ± 45 ms. Second- or third-degree atrioventricular block did not occur during the ablation procedure. During the followup of 19 ± 20 months none of the patients developed symptoms suggestive of atrioventricular nodal reentrant tachycardia or evidence of second- or third-degree atrioventricular block. Conclusion These data suggest that atrioventricular node (retrograde) fast pathway ablation can apparently be safely performed in patients with common atrioventricular nodal reentrant tachycardia and a prolonged PR interval during sinus rhythm.

Nonthoracotomy lead systems for implantable cardioverter defibrillators (ICDs) have reduced operative mortality and morbidity as compared to epicardial lead systems but are usually associated with higher defibrillation thresholds (DFTs). The purpose of this prospective randomized trial was to investigate if the second defibrillation electrode in the left subclavian vein can increase defibrillation efficacy and decrease DFT as compared to the superior vena cava (SVC) position in nonthoracotomy lead systems for ICDs. Seventeen patients (mean age: 49.9 +/- 11.3 years, mean ejection fraction: 46.1% +/- 15.8%) were implanted with an investigational unipolar electrode (Medtronic 13001) used as the defibrillation anode. DFT testing was started in the SVC (n = 10, group A) or the left subclavian vein (n = 7, group B), and repeated in the alternative position starting at the DFT of the initial position. Fifteen patients were eligible for analysis (group A: n = 9, group B: n = 6). With the electrode in the SVC, ventricular fibrillation could be successfully terminated in 9 out of 15 patients (60%). In the left subclavian vein the success rate was 100% (P < 0.01). Mean DFT in the SVC was 13.0 +/- 5.2 J and in the left subclavian vein 10.2 +/- 4.9 J. DFTs in the left subclavian vein were either lower (group A: n = 5/9, group B: n = 5/6) or equal to the results in the SVC position (P < 0.001). Thus, the left subclavian vein appears to be a superior alternative for positioning of the defibrillation anode as compared to the SVC for nonthoracotomy lead systems using two separate leads.

Left ventricular (LV) hypertrophy is a common finding in patients with resistant hypertension and is associated with an impaired intramyocardial perfusion. Renal sympathetic denervation (RDN) has been shown to reduce blood pressure (BP) and sympathetic tone. In this pilot study we aimed to

Background: Catheter ablation is extensively used with curative intention in Atrial Fibrillation (AF). Radiofrequency ablation has long been standard of care, cryoballoon technology has emerged a feasible approach with promising results. Prospective multicenter registry data referring to both ablation technologies in AF ablation are lacking so far. We report data of the German ablation registry I with respect to efficacy and complication rates in PV ablation after the first index ablation with different energy sources for paroxysmal AF after 1 year follow-up (FU). Methods: All 2256 consecutively enrolled patients with symptomatic px AF of the German ablation registry I who underwent their 1 year FU were included in this analysis. The cohort was devided into two groups according to the ablation energy source used: cryoballoon ablation (group 1, n=604 [26.8%], median age 61 years, 64.2% men) and RF ablation (group 2, n=1652 [73.2%], median age 62 years, 62.8% men). Results: Procedural outcome is given in the Table. Acute success rates were similar in both groups (97.0% in cryo vs. 96.9% in RF; p=0.84). AF recurrence rate at 1 year FU was not significantly different between both groups (45.8% after cryoablation and 45.4% after RF ablation; p=0.87). Use of antiarrhythmic therapy at 1 year follow-up was slightly more common after RF ablation (32.1% vs. 27.5% after cryoablation; p

The unipolar system for transvenous defibrillation, consisting of a single right ventricular lead as the cathode and the device shell as anode, has been shown to combine low defibrillation thresholds (DFTs) and simple implantation techniques. We compared the defibrillation efficacy of this system with the defibrillation efficacy of a dual lead system with a 12-cm long defibrillation anode placed in the left subclavian vein. The data of 38 consecutive patients were retrospectively analyzed. The implantation of an active can system was attempted in 20 patients (group 1), and of the dual lead system in 18 patients (group 2). Both groups had comparable demographic data, cardiac disease, ventricular function, or clinical arrhythmia. The criterion for successful implantation was a DFT ofor = 24 J. This criterion was met in all 18 patients of group 2. The active can system could not be inserted in 3 of the 20 group 1 patients because of a DFT24 J. In these patients, the implantation of one (n = 2) or two (n = 1) additional transvenous leads was necessary to achieve a DFTor = 24 J. The DFTs of the 17 successfully implanted group 1 patients were not significantly different from the 18 patients in group 2 (12.3 +/- 5.7 J vs 10.8 +/- 4.8 J). The defibrillation impedance was similar in both groups (50.1 +/- 6.1 omega vs 48.9 +/- 5.2 omega). In group 1, both operation duration (66.8 +/- 17 min vs 80.8 +/- 11 min; P0.05) and fluoroscopy time (3.3 +/- 2.1 min vs 5.7 +/- 2.9 min; P0.05) were significantly shorter. Thus, the active can system allows reliable transvenous defibrillation and a marked reduction of operation duration and fluoroscopy time. The dual lead system, with an increased surface area defibrillation anode, seems to be a promising alternative for active can failures.

Bei der Anwendung von Radiofrequenzenergie entwickelt sich innerhalb des Stromkreises ein Temperaturanstieg im Bereich des geringsten Stromflusses und hochsten Widerstandes, d.h. es entsteht Widerstandswarme (Reichenbach 1983). Um die Frage nach dem Zusammenhang zwischen vorgewahlter Leistung und der am Elektroden-Gewebe-Ubergang entstehenden Temperatur zu beantworten, wurden 45 Ablationen mit dem Thermokatheter im leistungsgesteuerten Koagulationsmodus am isolierten Schweineherzen durchgefuhrt. Uber das integrierte Thermoelement wurde die Temperatur bei konstanten, empirisch gewahlten Leistungsabgaben von 13,17, 20 und 29 W und Applikationszeiten von 10 und 20 s kontinuierlich gemessen.

Eine wesentliche Voraussetzung fur die effiziente und sichere Anwendung der Katheterabiation mit Radiofrequenzstrom ist die genaue Messung und Analyse der biophysikalischen Parameter. Wahrend der Energieabgabe erfolgt die kontinuierliche Messung von Effektivstrom (IEff) und -Spannung (UEff). Daraus werden die Ausgangsleistung (PAusg) und die Impedanz Z (der Widerstand im Wechselstromkreis) berechnet: $${\rm P}_{{\rm Ausg}} {\rm = U}_{{\rm Eff}} {\rm \times I}_{{\rm Eff}}$$ (1) $${\rm Z = U}_{{\rm Eff}} {\rm /I}_{{\rm Eff}}$$ (2) Strom, Spannung, Ausgangsleistung, Impedanz und Temperatur wurden uber einen AD-Wandler digitalisiert und mit Hilfe eines speziell entwickelten Grafikprogramms auf einem Bildschirm online als Kurven dargestellt.

Voraussetzung fur eine breitere Anwendung der Methode mit leistungsgesteuer­tem Radiofrequenzstrom ist die Verbesserung der Sicherheit durch eine Stan­dardisierung der Mestechnik in den kommerziell erhaltlichen Geraten. Von ver­schiedenen Untersuchern wurde die Beobachtung gemacht, das bei gleicher Vorwahl der Ausgangsleistung verschiedener Gerate eines Typs, aber auch bei Generatoren verschiedener Firmen, unterschiedliche Effektivleistungen entstehen konnen. Bei einer Technik wie der leistungsgesteuerten Radiofrequenzablation, die auf der Anwendung eines empirisch bestimmten Leistungsbereichs beruht, kann dies fatale Folgen haben. Entsprechend der in dieser Untersuchung darge­stellten experimentellen und klinischen Befunde konnte durch die Integration der Impedanzmessung vor der Ablation in die Radiofrequenzgeneratoren die Sicher­heit der Methode verbessert werden. Aufgrund der beschriebenen Vorteile des temperaturkontrollierten Prinzips im Hinblick auf die Sicherheit der Methode sollten die Gerate sowohl eine Katheterabiation mit leistungsgesteuertem als auch temperaturkontrolliertem Radiofrequenzstrom mit automatischer Konstanthal­tung der einmal eingestellten Temperatur ermoglichen.

Bei den experimentellen Untersuchungen mit leistungsgesteuertem Radiofrequenzstrom hatten zu hohe Leistungen oder Applikationszeiten zu Gasblasenbildungen — zum Teil mit Explosionen — und Myokardverletzungen gefuhrt. 90% der unerwunschten Wirkungen gingen mit einem Anstieg der Impedanz wahrend der Energieabgabe einher und der Elektrodenkatheter war karbonisiert. Auch beim Patienten traten, wie im nachsten Kapitel beschrieben, solche Impedanzanstiege auf, die in einigen Fallen auch mit horbaren Explosionen verbunden waren. Es ist anzunehmen, das bei diesen Impedanzanstiegen am Myokard des Patienten die gleichen Veranderungen auftreten wie bei den experimentellen Untersuchungen und diese prinzipiell auch zu Komplikationen fuhren konnen.

Lead failures constitute a major risk for patients with an implantable cardioverter defibrillator (ICD). However, data about the incidence and patterns of ICD-lead failures in a larger population are lacking. We analyzed the short-term and midterm performance of 27 epicardial and 103 nonthoracotomy ICD-lead systems during a follow-up period of 36 +/- 21 months and 22 +/- 10 months, respectively (p0.05). The failure rate was 5 (19%) of 27 in the epicardial and 6 (6%) of 103 in the nonthoracotomy group (p0.05). The most common symptom was erroneous detection of ventricular fibrillation from artifact sensing in five patients. Two patients had to be resuscitated because of failure to defibrillate. Loss of pacing and loss of sensing were seen in two patients. Only two asymptomatic lead fractures could be diagnosed on routine radiograph. In conclusion, there was a considerable rate of lead failures, especially in epicardial systems. Long-term studies addressing the longevity of ICD leads, mechanisms of their failures, and improved diagnostic facilities are important to further increase the safety of this therapeutic approach.

Background A significant proportion of patients undergoing transcatheter aortic valve implantation (TAVI) have concomitant peripheral arterial disease (PAD), which plays a crucial role in the preinterventional selection process of determining an optimal vascular access site. The aim of our study was to determine the impact of PAD on clinical outcome after TAVI in a real-world setting. Methods A total of 1,315 patients (mean logistic European System for Cardiac Operative Risk Evaluation 20.6% ± 13.7%) underwent TAVI in 27 centers and were included in the prospective German TAVI Registry. Results Of the 1,315 patients with TAVI, 330 (25.1%) had PAD. These patients had a higher logistic European System for Cardiac Operative Risk Evaluation score (27.7% ± 16.0% vs 18.3% ± 12.0%, P P P P P P P = .004) after TAVI. Conclusions In this real-world TAVI Registry, PAD was an independent predictor of mortality in patients with percutaneous and surgical TAVI, including vascular complications. Assessment of PAD should play a crucial role in the preinterventional selection process, regardless of the access strategy.

REITHMANN, C., et al.: Suppression of Concealed Pulmonary Vein Bigeminy by Atrial Pacing in a Patient with Paroxysmal Atrial Fibrillation. Concealed pulmonary vein bigeminy, as a pair of a pulmonary vein spike potential within a fragmented far-field atrial electrogram and a premature ectopic pulmonary vein spike potential with exit block, was continuously recorded in a patient with paroxysmal AF. Atrial pacing suppressed the breakthrough from the left atrium to the pulmonary vein, thus preventing the conducted and the premature ectopic pulmonary vein potentials. Atrial pacing induced conduction block between the left atrium and the arrhythmogenic pulmonary vein might be a possible explanation for the prevention of paroxysmal AF by atrial pacing.

We compared the electrophysiologic and clinical effects of oral cibenzoline and sotalol in 12 patients with spontaneous and inducible sustained ventricular tachycardia (VT), using a randomized, open-label, cross-over study. Electrophysiologic studies were performed in the control state, after oral cibenzoline and after oral sotalol, using an incremental dose-titration protocol. Therapy with cibenzoline at the maximum dose level (130-390 mg/day) resulted in complete suppression of VT in 1 of 12 patients (8%). Sotalol (160-320 mg/day) prevented induction of VT in 4 of 12 patients (33%). The effective refractory period (ERP) of the right ventricle was more significantly prolonged with sotalol (p < 0.001) as compared with cibenzoline (p < 0.05). Neither drug prolonged QT duration corrected for frequency (QTc) and cycle length of induced VT, as compared with the control study. Three patients experienced spontaneous VT after cibenzoline administration, and 2 patients experienced incessant VT during programmed electrical stimulation. No patient had a proarrhythmic effect while receiving oral sotalol treatment. Chronic sotalol therapy maintained long-term arrhythmia suppression in all 4 responders at 1-year follow-up. Sotalol appears to have greater efficacy than and a safety profile superior to that of cibenzoline. Drug-related proarrhythmic effects of oral cibenzoline therapy occurred with greater frequency than that associated with other antiarrhythmic drugs. Based on these findings, cibenzoline cannot be recommended for use in patients with VT.

Antiarrhythmic drug therapy guided by invasive electrophysiologic testing is now widely used in patients with symptomatic, sustained ventricular tachyarrhythmias.We conducted a prospective, randomized trial in 170 patients to investigate whether this approach would improve long-term outcome. Patients whose arrhythmia was inducible by programmed electrical stimulation were assigned to treatment with electrophysiologically guided drug therapy based on serial testing (61 patients) or with metoprolol (54 patients). Electrophysiologically guided therapy consisted of serial testing of antiarrhythmic agents to identify the first one that rendered the arrhythmia noninducible. The 55 patients whose arrhythmia was noninducible during the initial electrophysiologic test were also treated with metoprolol.During a mean (+/- SD) follow-up period of 23 +/- 17 months, recurrent, nonfatal arrhythmia occurred in 44 patients and sudden death due to cardiac factors in 27. The incidence of symptomatic arrhythmia and sudden death combined was virtually the same in the two groups with inducible arrhythmia after two years of observation (electrophysiologically guided therapy vs. metoprolol therapy, 46 percent vs. 48 percent). The outcome was more favorable in the patients with noninducible arrhythmia at base line (75 percent had neither adverse event) than in those with inducible arrhythmia who were assigned to metoprolol therapy (P = 0.009 by log-rank test). Only 6 of the 29 patients (21 percent) with inducible arrhythmia that became noninducible during drug therapy had recurrent arrhythmia or sudden death, as compared with 21 of the 32 patients (66 percent) with arrhythmia that continued to be inducible (P less than 0.001). A multivariate regression analysis identified continued inducibility of the arrhythmia as an independent predictor of recurrent arrhythmia or sudden death (relative risk, 7.3; 95 percent confidence interval, 2.3 to 23.2; P less than 0.001).As compared with metoprolol therapy, electrophysiologically guided antiarrhythmic drug therapy did not improve the overall outcome of patients with sustained ventricular tachyarrhythmias. However, effective suppression of inducible arrhythmia by antiarrhythmic drugs was associated with a better outcome than was lack of suppression.