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Aims The medical need for screening of aortic valve stenosis (AS), which leads to timely and appropriate medical intervention, is rapidly increasing because of the high prevalence of AS in elderly population. This study aimed to establish a screening method using understandable artificial intelligence (AI) to detect severe AS based on heart sounds and to package the built AI into a smartphone application. Methods and results In this diagnostic accuracy study, we developed multiple convolutional neural networks (CNNs) using a modified stratified five-fold cross-validation to detect severe AS in electronic heart sound data recorded at three auscultation locations. Clinical validation was performed with the developed smartphone application in an independent cohort (model establishment: n = 556, clinical validation: n = 132). Our ensemble technique integrating the heart sounds from multiple auscultation locations increased the detection accuracy of CNN model by compensating detection errors. The established smartphone application achieved a sensitivity, specificity, accuracy, and F1 value of 97.6% (41/42), 94.4% (85/90), 95.7% (126/132), and 0.93, respectively, which were higher compared with the consensus of cardiologists (81.0%, 93.3%, 89.4%, and 0.829, respectively), implying a good utility for severe AS screening. The Gradient-based Class Activation Map demonstrated that the built AIs could focus on specific heart sounds to differentiate the severity of AS. Conclusions Our CNN model combining multiple auscultation locations and exported on smartphone application could efficiently identify severe AS based on heart sounds. The visual explanation of AI decisions for heart sounds was interpretable. These technologies may support medical training and remote consultations.

Esophageal thermal lesions following pulmonary vein isolation (PVI) for atrial fibrillation (AF) potentially harbor lethal complications. Radiofrequency (RF)-PVI using contact force-technology can reduce collateral damage. We evaluated the incidence of endoscopically detected esophageal lesions (EDEL) and the contribution of contact force to esophageal lesion formation without esophageal temperature monitoring. One hundred and thirty-one AF patients underwent contact force-guided RF-PVI. Contact force, energy, force-time-integral, and force-power-time-integral were adopted. During PVI at the posterior segment of the wide antral circumferential line, limits were set for energy (30 W), duration (30 s) and contact force (40 g). Ablations were analyzed postero-superior and -inferior around PVs. Endoscopy within 120 h identified EDEL in six patients (4.6%). In EDEL(+), obesity was less frequent (17% vs. 68%, p = 0.018), creatinine was higher (1.55 ± 1.18 vs. 1.07 ± 0.42 mg/dL, p = 0.016), and exclusively at the left postero-inferior site, force-time-integral and force-power-time-integral were greater (2973 ± 3267 vs. 1757 ± 1262 g·s, p = 0.042 and 83,547 ± 105,940 vs. 43,556 ± 35,255 g·J, p = 0.022, respectively) as compared to EDEL(−) patients. No major complications occurred. At 12 months, arrhythmia-free survival was 74%. The incidence of EDEL was low after contact force-guided RF-PVI. Implementing combined contact force-indices on the postero-inferior site of left-sided PVs may reduce EDEL.

The hyperpolarization-activated cation current If is a key determinant for cardiac pacemaker activity. It is conducted by subunits of the hyperpolarization-activated cyclic nucleotide–gated (HCN) channel family, of which HCN4 is predominant in mammalian heart. Both loss-of-function and gain-of-function mutations of the HCN4 gene are associated with sinus node dysfunction in humans; however, their functional impact is not fully understood yet. Here, we sought to characterize a HCN4 V759I variant detected in a patient with a family history of sick sinus syndrome. The genomic analysis yielded a mono-allelic HCN4 V759I variant in a 49-year-old woman presenting with a family history of sick sinus syndrome. This HCN4 variant was previously classified as putatively pathogenic because genetically linked to sudden infant death syndrome and malignant epilepsy. However, detailed electrophysiological and cell biological characterization of HCN4 V759I in Xenopus laevis oocytes and embryonic rat cardiomyocytes, respectively, did not reveal any obvious abnormality. Voltage dependence and kinetics of mutant channel activation, modulation of cAMP-gating by the neuronal HCN channel auxiliary subunit PEX5R, and cell surface expression were indistinguishable from wild-type HCN4. In good agreement, the clinically likewise affected mother of the patient does not exhibit the reported HCN4 variance. HCN4 V759I resembles an innocuous genetic HCN channel variant, which is not sufficient to disturb cardiac pacemaking. Once more, our work emphasizes the importance of careful functional interpretation of genetic findings not only in the context of hereditary cardiac arrhythmias.

The aim of the present study was to determine whether free thyroxine (FT4) and calculated thyroid parameters predict the incidence of ventricular arrhythmias in euthyroid heart failure patients with implantable cardioverter-defibrillators (ICD). In this open-label prospective cohort study, 115 consecutive euthyroid patients (mean age 62.9 ± 1.3 years; 87% male; ischemic cardiomyopathy 63%) scheduled for primary prevention ICD implantation or exchange were enrolled. Serum concentrations of thyrotropin (thyroid-stimulating hormone) and FT4 were measured 1 day before device operation. Primary and secondary end points were defined as occurrence of appropriate ICD therapy (AIT) and cardiovascular death, respectively. During a mean follow-up of 1,191 ± 35 days, 24 patients (21%) experienced AIT, and cardiovascular death was observed in 10 patients (9%). Patients with AIT had higher FT4 concentrations compared with those without AIT (18.9 ± 0.48 vs 16.2 ± 0.22 pmol/L, p0.001). FT4 was an independent predictor of AIT in an adjusted Cox regression (hazard ratio = 1.47, p0.001). Kaplan-Meier analysis demonstrated that Jostel's thyroid-stimulating hormone index, reflecting the central component of the hypothalamus-pituitary-thyroid loop, and SPINA-GT as surrogate markers for thyroid's secretory capacity predicted AIT incidences. None of the indices predicted cardiovascular death. In conclusion, FT4 concentration predicts an increased incidence of ventricular arrhythmias in euthyroid patients receiving ICDs for primary prevention. Our data suggest that both impending primary hyperthyroidism and an increased thyroid homeostasis set point may increase the rate of AIT in this patient population.

Objective For risk stratification of sudden cardiac death in patients with structural heart disease, more precise predictors in addition to left ventricular ejection fraction (LVEF) are clinically needed. The present study assessed the utility of galectin-3 as an independent indicator for the prognosis of heart failure patients with implantable cardioverter-defibrillators (ICD). Methods The study population consisted of 91 consecutive patients who underwent a routine ICD checkup in our ICD outpatient clinic. Circulating galectin-3 was assessed using a commercially available enzyme-linked immunosorbent assay kit. The enrolled patients were prospectively followed. The primary endpoint was defined as the occurrence of appropriate ICD therapy (AIT), and the secondary endpoint was defined as the occurrence of unplanned overnight hospitalization due to decompensated heart failure (dHF). Results During a mean follow-up of 472±107 days, AIT occurred in 18 patients (20%). Unplanned hospitalizations due to dHF were noted in 12 patients (13%). A receiver-operative characteristics analysis demonstrated a sensitivity of 83% and specificity of 68% for AIT occurrences with a galectin-3 cut-off value of 13.1 ng/mL (area under the curve =0.82). A Kaplan-Meier analysis demonstrated that patients with galectin-313.1 ng/mL had significantly higher incidences of AIT as compared to those with lower galectin-3 (log-rank, p0.001). This significance was also observed in both subgroup analyses with ischemic and non-ischemic etiology. Cox regression demonstrated that higher galectin-3 was an independent predictor of AIT and dHF, even after adjusting for previous arrhythmic events. Conclusion The circulating galectin-3 level can be used as a clinical indicator of subsequent occurrence of ventricular arrhythmic events and decompensated heart failure, regardless of a history of ventricular arrhythmias.

Background Aortic stenosis is still one of the major causes of sudden cardiac death in the elderly. Noninvasive screening for severe aortic valve stenosis (AS) may result in early cardiac diagnostic leading to an appropriate and timely medical intervention. Purpose The aims of this study were 1) to develop an artificial intelligence to detect severe AS based on heart sounds and 2) to build an application to screen patients using electronic stethoscope and smartphones, which will provide an efficient diagnostic workflow for screening as a complementary tool in daily clinical practice. Methods We enrolled 100 patients diagnosed with severe AS and 200 patients without severe AS (no echocardiographic sign of AS [n=100], mild AS [n=50], moderate AS [n=50]). The heart sounds were recorded in 4000 Hz waveform audio format at the following 3 sites of each patient; the 2nd intercostal right sternal border, the Erb's area and the apex. Each record was divided into multiple data of 4 seconds duration, which built 10800 sound records in total. We developed multiple convolutional neural networks (CNN) designed to recognize severe AS in heart sounds according to the recorded 3 sites. We adopted a stratified 4-fold cross-validation method by which the CNN was trained with 60% of the whole data, validated with 20% data and tested with the remaining 20% data not used during training and validation. As performance metrics we adopted the accuracy, F1 value and the area under the curve (AUC) calculated as the average of all cross-validation folds. For the smartphone application, we combined the best CNN-models from each recorded site for the best performance. Further 40 patients were newly enrolled for its clinical validation (no AS [n=10], mild AS [n=10], moderate AS [n=10], severe AS [n=10]). Results The accuracy, F1 value and AUC of each model were 88.9±5.7%, 0.888±0.006 and 0.953±0.008, respectively. The sensitivity and specificity were 87.9±2.2% and 89.9±2.4%. The recognition accuracy of moderate AS was significantly lower as compared to the other AS grades (moderate AS 74.1±6.1% vs no AS 98.0±1.4%, mild AS 97.6±1.2%, severe AS 87.9±2.2%, respectively, P Our smartphone application showed a sensitivity of 100% (10/10), a specificity of 73.3% (22/30), and an accuracy of 80.0% (32/40), which implicated a good utility for screening. In the detailed analysis of 8 mistaken decisions, these were highly affected by the presence of severe mitral or tricuspid valve regurgitation despite of non-severe AS (7/8 [87.5%]). Conclusions This study demonstrated the promising possibility of an end-to-end screening for severe aortic valve stenosis using an electronic stethoscope and a smartphone application. This technology may improve the efficacy of daily medicine particularly where the human resource is limited or support a remote medical consultation. Further investigations are necessary to increase accuracy. Funding Acknowledgement Type of funding sources: None.

Artificial intelligence (AI) is developing rapidly in the medical technology field, particularly in image analysis. ECG-diagnosis is an image analysis in the sense that cardiologists assess the waveforms presented in a 2-dimensional image. We hypothesized that an AI using a convolutional neural network (CNN) may also recognize ECG images and patterns accurately. We used the PTB ECG database consisting of 289 ECGs including 148 myocardial infarction (MI) cases to develop a CNN to recognize MI in ECG. Our CNN model, equipped with 6-layer architecture, was trained with training-set ECGs. After that, our CNN and 10 physicians are tested with test-set ECGs and compared their MI recognition capability in metrics F1 (harmonic mean of precision and recall) and accuracy. The F1 and accuracy by our CNN were significantly higher (83 ± 4%, 81 ± 4%) as compared to physicians (70 ± 7%, 67 ± 7%, P

Background The prognostic implications of non-sustained ventricular tachycardia (NSVT) and their significance as therapeutic targets in patients without prior sustained ventricular arrhythmias remain undetermined. The aim of this study was to investigate the prognostic significance of asymptomatic NSVT in patients who had primary prevention implantable cardioverter-defibrillator (ICD) implantation due to ischemic or non-ischemic cardiomyopathy (ICM, NICM). Methods We enrolled 157 consecutive primary prevention ICD patients without previous appropriate ICD therapy (AIT). Patients were allocated to two groups depending on the presence or absence of NSVT in a 6-month period prior to enrollment. The incidence of AIT and unplanned hospitalization due to decompensated heart failure (HF) were assessed during follow-up. Results In 51 patients (32%), precedent NSVT was documented. During a median follow-up of 1011 days, AIT occurred in 36 patients (23%) and unplanned HF hospitalization was observed in 32 patients (20%). In precedent NSVT patients, the incidence of AIT and unplanned HF hospitalization was significantly higher as compared to patients without precedent NSVT (AIT: 29/51 [57%] vs. 7/106 [7%], P P = 0.043, log-rank). Cox-regression demonstrated that precedent NSVT independently predicted AIT (P P P = 0.020), but predicted HF hospitalization only in patients with ICM (P = 0.0030). Conclusions Precedent non-sustained VT in patients with primary prevention ICDs is associated with subsequent appropriate ICD therapies, and is an independent predictor of unplanned heart failure hospitalizations in patients with ischemic cardiomyopathy.

Introduction The single-chamber implantable cardioverter-defibrillator (ICD) can be associated with more frequent inappropriate therapies compared with dual-chamber ICDs, when they are accompanied by a simpler implantation procedure. The aim of this study was to investigate whether the use of a single-lead ICD system with atrial-sensing electrodes results in a reduction of inappropriate ICD therapy. Methods and results The study population consisted of 212 consecutive patients, who underwent primary prophylactic single-lead ICD implantation at our institute. A ventricular lead with atrial-sensing electrodes was implanted in 77 patients (36%; Group-VDD) and a ventricular lead without atrial-sensing electrodes was implanted in 135 patients (64%; Group-VVI). Procedural and follow-up data were collected in a prospective registry. A higher prevalence of atrial fibrillation was present in Group-VDD. There were no other significant differences in patient baseline characteristics (age, sex, and other comorbidities) or follow-up period between the two groups. The operative parameters including fluoroscopic burden showed no significant differences between Group-VDD and Group-VVI. During a mean follow-up period of 697 ± 392 days, 26 patients (12%) experienced appropriate ICD therapies and 13 patients (6%) suffered inappropriate ICD therapies. The incidence of inappropriate ICD therapies in Group-VDD was significantly lower as compared to that of Group-VVI (1/77 [1%] vs 12/135 [9%]; log-rank, P = 0.028). The incidence of appropriate ICD therapies and the occurrence of device-related complications showed no significant difference between the two groups. Conclusion Single-lead ICD with atrial-sensing electrodes shows a lower incidence of inappropriate ICD therapy compared with the absence of atrial-sensing electrodes, without additional operative burden or increased complications.

Background: The severity of symptoms during atrial fibrillation (AF) may be influenced by heart rate and blood pressure variation, due to irregular beats and the related adaptations in baroreflex sensitivity. This study investigated whether heart rate turbulence (HRT) as a reflection of baroreflex sensitivity is related to symptom severity during AF. Method: Ninety-seven patients (pts) who underwent electrophysiological study were enrolled. Consecutive 56 pts had paroxysmal AF (21 with milder symptoms [EHRA I or II; Group-M], 35 with severe symptoms [EHRA III or IV; Group-S]), and 41 age-matched controls without AF were included. After delivering a single ventricular extrastimulus during sinus rhythm and repeating the process 10 times, the quantification of HRT was performed by measuring turbulence onset (TO: heart rate acceleration) and turbulence slope (TS: rate of heart rate deceleration). Results: Group-M pts showed significantly diminished TO as compared to controls and Group-S pts (P = 0.012). There was no significant difference of the TS between the 3 groups. Given that a TO ≥ 0% or TS ≤ 2.5 ms/RR was considered abnormal, Group-M pts showed significantly higher incidences of abnormal HRT as compared to controls and Group-S pts (71% vs 40% vs 21%, respectively, P = 0.0012). Regression analysis demonstrated an independent and significant association between a diminished TO and milder AF symptoms (P

Syncope is one of the most frequent mode of hospital visits in the emergency department. A broad range of causalities and healthcare economic efficiency have demanded reasonable road maps for diagnostic procedures and hospital admission of patients with syncope. Recent advances and multidisciplinary assessments provided the basis of the updated 2018 ESC Guidelines for the diagnosis and management of syncope. While the definitions of syncope remain unchanged these updates state risk stratification in the emergency department with clear diagnostic paths and monitoring in the current era with portable devices. The algorithm for reflex syncope therapy, indication for cardiac pacemakers and implantable cardioverter-defibrillators in high-risk patients for sudden cardiac death were modified. Finally, the updated guidelines recommend an establishment of "syncope-unit" with multidisciplinary involvement.INITIALE ABKLäRUNG UND RISIKOSTRATIFIZIERUNG: Die neue Leitlinie bietet eine klare Anleitung zur sicheren und effizienten Abklärung und Therapie von Patienten mit Synkopen. Neue Konzepte beinhalten Strategien zur Risikostratifizierung, vernünftigen Entscheidung für den diagnostischen Pfad sowie restriktive Kriterien für eine stationäre Aufnahme.Aufwertung des EKG-Monitorings mittels implantierbarem Loop-Rekorder (ILR). Bewertung des Kipptisch-Tests als Bestätigungstest bei V. a. Reflexsynkope oder Nachweis einer unspezifischen Hypotonie-Neigung. Videoaufzeichnungen durch Smartphones werden einbezogen. VORGEHEN BEI UNGEKLäRTER SYNKOPE: Empfehlung zu einem klaren diagnostischen Entscheidungspfad zum Asystolie-Nachweis für Patienten 40 Jahre mit schweren, rezidivierenden und unvorhersehbaren (ohne Prodromi einsetzenden) Synkopen.Geänderte Algorithmen zur Therapie von Reflexsynkopen inkl. der seltenen Indikationsstellung zur Schrittmachertherapie. Indikation zur Implantation eines ICD (implantierbarer Kardioverter-Defibrillator) bei hohem Risiko für den plötzlichen Herztod.Interdisziplinäre Synkopen-Einheiten werden empfohlen.

Pulmonary vein isolation (PVI) is a cornerstone therapy in patients with atrial fibrillation (AF). With increasing numbers of PVI procedures, demand arises to reduce the cumulative fluoroscopic radiation exposure for both the physician and the patient. New technologies are emerging to address this issue. Here, we report our first experiences with a new fluoroscopy integrating technology in addition to a current 3D-mapping system. The new fluoroscopy integrating system (FIS) with 3D-mapping was used prospectively in 15 patients with AF. Control PVI cases (n = 37) were collected retrospectively as a complete series. Total procedure time (skin to skin), fluoroscopic time, and dose-area-product (DAP) data were analyzed. All PVI procedures were performed by one experienced physician using a commercially available circular multipolar irrigated ablation catheter. All PVI procedures were successfully undertaken without major complications. Baseline characteristics of the two groups showed no significant differences. In the group using the FIS, the fluoroscopic time and DAP were significantly reduced from 571 ± 187 seconds versus 1011 ± 527 seconds (P = 0.0029) and 4342 ± 2073 cGycm(2) versus 6208 ± 3314 cGycm(2) (P = 0.049), respectively. Mean procedure time was not significantly affected and was 114 ± 31 minutes versus 104 ± 24 minutes (P = 0.23) by the FIS.The use of the new FIS with the current 3D-mapping system enables a significant reduction of the total fluoroscopy time and DAP compared to the previous combination of 3D-mapping system plus normal fluoroscopy during PVI utilizing a circular multipolar irrigated ablation catheter. However, the concomitant total procedure time is not affected. Thus, the new system reduces the radiation exposure for both the physicians and patients.

Background Subclinical atrial fibrillation is one possible cause of embolic stroke of undetermined source ( ESUS ). It remains to be elucidated if a specific infarction site has a predictive value for detecting subclinical atrial fibrillation. We aimed to investigate the predictive value of infarction site in patients with ESUS for the detection of atrial tachyarrhythmia ( AT ) using an insertable cardiac monitor. Methods and Results Consecutive 146 patients (84 men; aged 62±12 years) underwent insertable cardiac monitor implantation after diagnosis of ESUS . The detection of AT >30 seconds was evaluated. The ESUS infarction sites were categorized into internal carotid artery and vertebral artery ( VA ) territories, with ophthalmic artery, anterior cerebral artery, and middle cerebral artery as internal carotid artery subterritories, and posterior cerebral artery and other vertebrobasilar arteries as VA subterritories. During a median follow‐up of 387 days, AT was detected in 33 patients (23%). Subclinical AT detection was significantly more frequent after VA territorial infarction opposed to internal carotid artery infarction (20/57 [35%] versus 13/89 [15%]; P =0.0039). Kaplan‐Meier analysis demonstrated a significantly higher AT detection rate after VA infarction (log‐rank, P =0.0076). Regression analysis revealed that VA territorial infarction, and particularly posterior cerebral artery area infarction, was an independent predictor of AT detection. Conclusions Patients with ESUS in the posterior cerebral artery territory had a higher rate of subclinical AT detection than those with other infarct localizations. Our data suggest that the possible usefulness of ESUS site to identify candidates for direct oral anticoagulation should be confirmed in future research.

The use of a novel irrigated multipolar ablation and mapping catheter for pulmonary vein isolation in patients with atrial fibrillation (AF) has demonstrated reasonable acute success rates and short procedure times, however, long-term outcome data are limited. The aim of this study was to analyze the long-term efficacy of this novel ablation system utilizing a reduced power setting for safety purposes.A total of 89 patients with paroxysmal (63 of 89 patients; 71%) or persistent AF underwent PVI with a reduced power setting of maximum 20 Watts (W) unipolar radiofrequency energy and 30 seconds in duration. In cases of persistent AF, atrial substrate ablation was performed additionally. Follow-up was based on outpatient clinic visits at 3, 6, and 12 months and included 5-day Holter ECGs. All of the 347 identified pulmonary veins were successfully isolated. Mean procedure times in PVI and PVI plus substrate ablation were 102 ± 25 minutes and 126 ± 32 minutes, respectively, applying a mean total radiofrequency time of 14 ± 6 minutes and 19 ± 9 minutes. Mean fluoroscopy time was 17 ± 8 minutes and 18 ± 6 minutes, respectively. Follow-up was available for all 89 patients. At one-year follow-up, 44 (70%) patients with paroxysmal AF and 11 (42%) patients with persistent AF remained in stable sinus rhythm after a singleprocedure and off antiarrhythmic drugs.The use of a novel irrigated multipolar ablation catheter with a reduced power setting is safe and feasible, and demonstrates a one-year success rate of 70% in paroxysmal AF and 42% in persistent AF.

Das Vorhandensein eines „slow pathway“ und eines „fast pathway“ innerhalb des AV-Knotens sind entscheidend fur das Auftreten der AV-Knoten-Reentry-Tachykardien. Eine verwandte Arrhythmie ist eine Nicht-Reentry-Tachykardie, welche ebenfalls durch die zeitversetzte Erregungsausbreitung uber den AV-Knoten entsteht. Bei der haufig als duale AV-Knoten-Nicht-Reentry-Tachykardie (DAVNNT) bezeichneten Arrhythmie erfolgt die Erregungsausbreitung jedoch nicht als kreisende Erregung, sondern uber eine zeitversetzte antegrade Leitung. Dabei folgen auf eine Sinusknotenaktivierung zwei gekoppelte, zeitlich nacheinander folgende Depolarisationen der Ventrikel. In der jungeren Vergangenheit wurde wiederholt spekuliert, ob es sich um eine unterdiagnostizierte Arrhythmie handelt. Auf Grund der schwerwiegenden therapeutischen Konsequenzen, die sich aus dieser bisher moglicherweise noch haufig verkannten Differenzialdiagnose ergeben, ist es das Ziel der vorliegenden Arbeit, unsere Erfahrungen in der Diagnostik und Behandlung der DAVNNT an Hand einer Fallserie darzustellen und eine Ubersicht uber den aktuellen Kenntnisstand zu geben.

Pulmonary vein isolation (PVI) as a cornerstone for catheter ablation of atrial fibrillation (AF) remains a complex and time-consuming procedure.To assess feasibility, safety, and acute efficacy of a novel irrigated multielectrode ablation catheter guided by an electroanatomic mapping system for PVI in patients with paroxysmal AF.Twenty-five consecutive patients (60 ± 10 years) with paroxysmal AF underwent PVI by using a novel decapolar mapping and ablation catheter (nMARQ catheter, Biosense Webster Inc, Diamond Bar, CA). Ablation was guided by electroanatomic mapping allowing radiofrequency (RF) energy delivery in the antral region of pulmonary veins (PVs) from 10 irrigated electrodes simultaneously. The day after ablation, cardiac magnetic resonance imaging was performed routinely in order to assess for potential acute PV stenosis.Overall, 97 of 97 (100%) targeted PVs could be isolated with a mean of 27 ± 11 RF applications and a mean total burning time of 15 ± 6 minutes per patient. The total procedure time from femoral vein access to catheter withdrawal was 110 ± 31 minutes, including a mean total fluoroscopy time of 23 ± 9 minutes. On average, 6 ± 3 RF impulses with a maximum of 25 W were applied per vein. After a short learning curve, procedure, fluoroscopy, and total burning times decreased to 94 ± 16, 16 ± 3, and 9 ± 2 minutes, respectively (P.05). Entrance and exit blocks could be verified by placing the ablation catheter into 90 of 97 (93%) PVs in 18 of 25 (72%) patients. No procedure-related complications were observed, especially no acute PV stenosis could be detected.The use of a novel irrigated multielectrode ablation system for PVI is feasible and safe, resulting in acute isolation of all targeted PVs with no complications and short procedure times. Sustainability of these initial results has to be confirmed in long-term efficacy and follow-up trials.

Background/Aims: Pannexin-1 (Panx1) is an ATP release channel that is ubiquitously expressed and coupled to several ligand-gated receptors. In isolated cardiac myocytes, Panx1 forms large conductance channels that can be activated by Ca2+ release from the sarcoplasmic reticulum. Here we characterized the electrophysiological function of these channels in the heart in vivo, taking recourse to mice with Panx1 ablation. Methods: Cardiac phenotyping of Panx1 knock-out mice (Panx1-/-) was performed by employing a molecular, cellular and functional approach, including echocardiography, surface and telemetric ECG recordings with QT analysis, physical stress testing and quantification of heart rate variability. In addition, an in vivo electrophysiological study entailed programmed electrical stimulation using an intracardiac octapolar catheter. Results: Panx1 deficiency results in a higher incidence of AV-block, delayed ventricular depolarisation, significant prolongation of QT- and rate corrected QT-interval and a higher incidence of atrial fibrillation after intraatrial burst stimulation. Conclusion: Panx1 seems to play an important role in murine cardiac electrophysiology and warrants further consideration in the context of hereditary forms of atrial fibrillation.

Introduction Ablation of the cavotricuspid isthmus (CTI) in patients with atrial flutter (AFL) and pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) are both common therapies. As the demand for ablative treatments rises, total radiation exposure times of staff increase concomitantly. Here, we report on our first experiences with a new fluoroscopy integrating system (FIS) integrated into a current 3D mapping system (3DMS). Material and methods The study population consisted of 59 consecutive patients who underwent PVI or CTI ablation (26 and 33 patients with and without FIS respectively). Total procedure time (PT), fluoroscopy exposure time (FT) and dose-area product (DAP) were monitored. Results All procedures were successfully completed without major complications. Employing FIS in the PVI group, FT and DAP were both significantly reduced after completing a short learning curve of 6 cases (respectively 361.6 ±181 s vs. 530.3 ±156.7 s, p = 0.039; 801.9 ±439.15 cGycm² vs. 1495 ±435.2 cGycm², p = 0.002). Mean PT was not significantly affected (121 ±26.7 min vs. 135.6 ±23.2 min, p = 0.21). The same holds true for CTI ablation: FT (99.29 ±51.4 s vs. 153.9 ±76.6 s, p = 0.022) and DAP (269 ±128.7 cGycm² vs. 524.3 ±288.4 cGycm², p = 0.002) were significantly reduced, leaving PT not significantly affected (29.5 ±10 min vs. 35.2 ±16.3 min, p = 0.23). Conclusions The introduction of the new FIS with a current 3DMS results in a significant reduction of both the total FT and DAP without affecting PT. The initial learning curve for adopting this method is considerably short.

The dual atrioventricular nodal nonreentry tachycardia (DAVNNT) is a rare form of tachycardia which occurs due to a time delayed double antegrade conduction via the slow and fast atrioventricular nodal pathways. Its epidemiology is not known so far. The aim of this article is to present the clinical findings in a series of patients with DAVNNT.We retrospectively analyzed our database of patients who successfully underwent radiofrequency catheter ablation between January 2012 and March 2013 due to diagnosed supraventricular tachycardia.In 3 out of 231 patients DAVNNT could be successfully treated by slow pathway modulation/ablation. Patients presented with widely varying symptoms including syncope, palpitations which had been mistaken as atrial fibrillation, and inappropriate defibrillator shocks due to suspected ventricular tachycardia.The DAVNNT seems to be more common than previously thought. This important differential diagnosis needs to be taken into consideration as slow pathway modulation can be curative while a misdiagnosis, such as atrial fibrillation or ventricular tachycardia might result in over-treatment in patients with this arrhythmia.

Background/Aims: TASK-1 is a potassium channel predominantly expressed in heart and brain. We have previously shown that anesthetized TASK-1 -/-mice have prolonged QT intervals in surface electrocardiograms (ECGs). In addition, heart rate variability quantified by time and frequency domain parameters was significantly altered in TASK-1 -/-mice with a sympathetic preponderance. Aims of the present study were the analysis of QT intervals by telemetric ECGs, to determine potential influences of anesthesia and β-adrenergic stimulation on repolarization in surface ECGs, to investigate in vivo electrophysiological parameters by intracardiac electrical stimulation and to quantify heart rate turbulence after ischemia/reperfusion or ventricular pacing in TASK-1 +/+ and TASK-1 -/-mice. Methods: Rate corrected QT intervals (QTc) were recorded in conscious mice by telemetry and in surface ECGs following administration of various anesthetics (tribromoethanol (Avertin®), pentobarbital and isoflurane). TASK-1 +/+ and TASK-1 -/mice were characterized by programmed electrical stimulation using an intracardiac octapolar catheter. The baroreceptor reflex was analyzed by heart rate turbulence (turbulence onset and slope) after ischemia/reperfusion and by stimulated premature ventricular contractions. Results: Telemetric and surface ECGs in mice sedated with Avertin®and pentobarbital, showed a significantly lengthened rate corrected QT interval in TASK-1 -/-mice (telemetry: TASK-1 +/+ 43±3ms vs. TASK-1 -/-49±5ms, n=6, p, The work was supported by grants from the University of Duesseldorf and by the German Society for Pediatric Cardiology.