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Abstract Introduction  AP localization can be predicted by analyzing the polarity of the delta wave, QRS polarity, and R/S ratio in patients with Wolff–Parkinson–White syndrome. However, the estimation of AP location is limited in patients with concealed pathways during atrioventricular reentrant tachycardias (AVRT). Thus, we analyzed retrograde P-wave polarity during orthodromic AVRT and developed an algorithm to predict the localization of concealed accessory pathways (AP). Methods and Results  A total number of 131 patients with a single AP and inducible orthodromic AVRT were included. The initial 61 patients were analyzed retrospectively for algorithm development, whereas 70 patients were evaluated prospectively. The retrograde P-wave polarity was analyzed by subtracting the superimposing T-wave during orthodromic AVRT using custom-designed software. Four leads of the surface electrocardiogram (ECG) were identified to accurately distinguish AP locations assigned to four different regions around each AV annulus: I, aVR, aVL, and V1. Lead V1 was used to differentiate right (negative or isoelectric) from left (solely positive) APs. Retrograde P-wave in lead I was negative in left posterior APs exclusively and became more positive with an AP location shifting towards right anterior. P-wave polarity in lead aVR demonstrated a shift from a positive polarity from left APs to isoelectric in right APs. The opposite direction (shift from positive to isoelectric) was observed for lead aVL. The subsequently developed algorithm for concealed AP localization using these surface ECG leads demonstrated a high sensitivity, specificity, and positive predictive value particularly for common AP localizations (left posterior and inferior, and right septal) when applied in a prospective fashion. Conclusion  Concealed AP localization can be accurately predicted by the analysis of retrograde P-wave polarity during orthodromic AVRT using the algorithm derived from the presented study. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary vein (PV) isolation for the curative treatment of atrial fibrillation using conventional radiofrequency ablation (RF) catheters with the point by point technique is time consuming and carries a remaining risk for thrombembolic complications.Aims of the Study: Aim of the present in vivo study was to evaluate feasibility and safety of a novel multipolar irrigated ablation catheter designed to create contiguous lesions encircling the PV ostium in a single ablation position.Methods: The entire ablation section (tripolar, length of each electrode 22 mm, interelectrode distance 2 mm, helix radius: 9 and 10 mm) of the 7F RF catheter (Encirclr, Medtronic, MN, USA) was covered by a porous membrane (pore size 30 micron) providing continuous irrigation. The helical formed catheter was used in two different experimental settings. Initially, a thigh muscle preparation has been performed in 7 anesthetized sheep in order to evaluate the development of lesions at different power level (40–80 W) and RF duration (30–90 sec). The ablation catheter was placed at the surface of the thigh muscle in a perpendicular position (0.1 N contact pressure) and perfused with heparinized blood (250 ml/min, 37C°). Irrigation was provided with a flow rate of 10 ml/min. The resulted lesion morphology was evaluated with regard to coagulum or crater formation and lesion depth and diameter. Subsequently in 9 anesthetized sheep intracardiac ablation has been achieved with 50 W and an irrigation flow of 10 ml/min. Transseptal puncture and RF ablations were guided using fluoroscopy and intracardiac echocardiography (ICE, Acuson, USA). Endpoint of the intracardiac RF applications was the reduction of local electrogram amplitude >50%. RF applications were achieved at both atrial appendages and in the orifices of the coronary sinus (CS), the vena cava inferior (VCI) and PV. Following RF ablation all animals were sacrificed and following in vivo staining (2% TTC) macroscopically and histologically investigations of the lesions were performed.Results: At the thigh muscle preparation 57 RF applications have been performed. The lesion depth was homogeneous without gaps between the ablation electrodes. There was a significant increase comparing 30 with 90 sec of RF duration for 40, 50 and 60 W applications respectively: 40 W: 1.1 ± 0.4 vs. 3.6 ± 0.5; 50 W: 1.2 ± 0.3 vs. 4.6 ± 0.4 mm and 60 W: 2.6 ± 0.6 vs. 4.8 ± 0.5 mm. All applications with 80 W (n = 3) had to be terminated due to immediate increase of impedance >150 ω . Late impedance rises (>60 sec) without occurrence of coagulum formation have been observed in 1 out of 4 RF applications with 60 W.A total of 85 RF applications could be achieved intracardiacally in the right atrium (right atrial appendage n = 18, ostium of the coronary sinus n = 12, ostium of the inferior caval vein: n = 12) and in the left atrium (left atrial appendage: n = 15, ostium of the PV: n = 28). ICE guided positioning of the catheter and showed during all applications no coagulum formation at the electrode or impedance rise (>150 Ω). Reduction of local electrograms (>50%) were observed following 48 out 85 (56%) RF applications. The lesions showed a homogeneous depth of 4 ± 2 mm and a width 5 ± 2 mm at the surface. No charring or crater formation could be observed in any of the lesions.Conclusions: In the present in vivo studies it could be demonstrated that long irrigated ablation electrodes induce continuous lesions without the risk of thrombus formation at the electrode. Increase of RF duration from 30 to 90 seconds with power setting of 40–60 W, respectively, created deeper lesions without the risk of thrombus formation. Thus, the helical formed irrigated ablation catheter appears to be appropriate for simplified PV isolation. [ABSTRACT FROM AUTHOR]

Zusammenfassung Hintergrund und Fragestellung: Vorhofflimmern (VHF) ist mit einer Pravalenz von bis zu 9% die haufigste Herzrhythmusstorung. In den letzten 15 Jahren hat die antiarrhythmische Therapie einen gro?en Wandel vollzogen. Ziel dieser Untersuchung war eine Bestandsaufnahme der aktuellen ambulanten Therapiegewohnheiten bei VHF in einer deutschen Gro?stadt. Methodik: Mittels eines Fragebogens bzw. eines Interviews wurden 312 zufallig ausgewahlte Arztinnen und Arzte (Allgemeinmediziner, Internisten und Kardiologen) aus allen Bezirken Berlins bezuglich der Praktiken zur Konversion, Rezidivprophylaxe und Antikoagulation bei VHF befragt. Ergebnisse: Es zeigte sich eine deutliche Zuruckhaltung im Einsatz international empfohlener Antiarrhythmika sowie der antikoagulatorischen Therapie. Die Konversion wird uber zu lange Zeit versucht. Schlussfolgerung: Das Ergebnis lasst Unsicherheit in der Therapie des VHF vermuten und erfordert eine starkere Prasenz der bestehenden internationalen Therapieleitlinie. [ABSTRACT FROM AUTHOR]