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Introduction and objectives: There are scarce data on left atrial (LA) enlargement and electrophysiological features in athletes. Methods: Multicenter observational study in competitive athletes and controls. LA enlargement was defined as LA volume indexed to body surface area ≥ 34mL/m2. We analyzed its relationship with atrial electrocardiography parameters. Results: We included 356 participants, 308 athletes (mean age: 36.4±11.6 years) and 48 controls (mean age: 49.3±16.1 years). Compared with controls, athletes had a higher mean LA volume index (29.8±8.6 vs 25.6±8.0mL/m2, P=.006) and a higher prevalence of LA enlargement (113 [36.7%] vs 5 [10.4%], P

Many drugs interact with ion channels in the cells of the heart and trigger heart rhythm disorders with potentially fatal consequences. Computational modeling can provide mechanistic insight into the onset and propagation of drug-induced arrhythmias, but the effect of drugs on the mechanical behavior of the heart remains poorly understood. Here we establish a multiphysics framework that integrates the biochemical, electrical, and mechanical effects of drugs from single cardiac cells to the overall response of the whole heart. For the example of the drug dofetilide, we show that drug concentrations of 3.0x and 4.8x increase the heart rate to 122 and 114 beats per minute, increase the myofiber stretches up to 10%, and decrease tissue relaxation by 6%. Strikingly, the drug-induced interventricular and atrial-ventricular dyssynchrony results in a 2.5% decreased and 7% increased cardiac output, respectively. Our results demonstrate the potential for multiphysics, multiscale modeling towards understanding the mechanical implications of drug-induced arrhythmias. Knowing how differing drug concentrations affect the performance of the heart has important clinical implications in drug safety evaluation and personalized medicine.

BACKGROUND Recent studies have shown that Evolution RL bidirectional rotational mechanical sheath (Cook Medical,USA) is an effective and safe technique for transvenous lead extraction (TLE). We reported our experience with the bidirectional rotational mechanical tools using a multidisciplinary approach highlighting the value of a joint cardiac surgeon and electrophysiologist collaboration. METHODS The study population comprised 84 patients (77%male;mean age 65±18 years) undergoing TLE.After multidisciplinary evaluation, a combined procedure was considered. RESULTS The main indication for TLE was infection in 54 cases (64%).Overall,152 leads were extracted with a mean implant duration of 94±63 months (range 12-421).Complete procedural success rate, clinical success rate, and lead removal with clinical success rate were 91.6 % (77/84),97.6% (82/84), and 98.6%(150/152), respectively.Eighteen combined procedure were performed in 12 patients (14%), such as "hybrid approach" (n = 2) or TLE concomitant to:1) transcatheter aspiration procedure for large vegetation (n = 8); 2) left ventricular assistance device implantation as bridge to cardiac transplantation (n = 1); 3) permanent pacing with epicardial leads (n = 6); 4) tricuspid valve replacement (n = 1).One major complication (1.2%) and 11 (13%) minor complications were encountered.No injury to the superior vena cava occurred and no procedure-related deaths were reported. During a mean time follow-up of 21±18 months, 17 patients (20%) died.They were more often diabetics (P = 0.02), and they underwent TLE more often for infection (P = 0.004). CONCLUSIONS Our results support the finding that excellent outcomes can be achieved in performing TLE of chronically implanted leads by using the Evolution RL bidirectional rotational mechanical sheath and a multidisciplinary team approach involving both electrophysiologist and cardiac surgeon as first line operators. This article is protected by copyright. All rights reserved.

The restoration and maintenance of sinus rhythm is a desirable strategy for many patients with atrial fibrillation (AF) since it has been associated with improvement in symptoms and a better quality of life. Sinus rhythm can be achieved by pharmacological or electrical cardioversion or after catheter ablation of AF. Despite high rates of successful cardioversion, AF recurrence remains a major challenge. Anti-arrhythmic drug therapy currently plays a significant role in maintaining sinus rhythm after cardioversion. Amiodarone is the most commonly prescribed anti-arrhythmic drug for patients with AF. This is due to its particular electrophysiological properties and superior anti-arrhythmic effects in comparison with other anti-arrhythmic drugs. Understanding the cardiac electrophysiology and arrhythmogenesis mechanisms may result in identification of new targets for anti-arrhythmic therapy. The aim of this article was to review amiodarone’s clinical pharmacology and evaluate evidence supporting amiodarone for treatment and prevention of AF recurrence after cardioversion.

Background. Radiofrequency catheter ablation (CA) has been the treatment of choice in patients with accessory pathway (AP)-mediated tachycardias. Most of these procedures are done under fluoroscopic guidance, leading to significant radiation exposure to the patient and the laboratory personnel. In this analysis, we have looked at the amount of radiation exposure in AP CA procedures performed without the support of a three-dimensional electroanatomic mapping system. We have analyzed changes in exposure indices over the study period and the impact of change in fluoroscopy frame rate (FFR). Objectives. The objectives of this study are to quantify radiation exposure in accessory pathway ablation procedures; to analyze the radiation exposure trend over time; and to evaluate the effect of fluoroscopy frame rate reduction on the radiation exposure indices in these procedures. Methods. All the AP ablation procedures performed at our institute from January 2016 to December 2019 were retrospectively analyzed. The collected data were age, sex, location of APs based on successful site of ablation on fluoroscopy, procedure time, fluoroscopy time, and dose-area product (DAP). Effective dose (ED) was estimated from DAP. The data of procedures performed before January 2018 (“pre” group) were compared with those of the procedures performed after that date (“post” group). Pre-group procedures were performed at an FFR of 7.5 frames per second (fps), and post-group procedures – at an FFR of 3.75 fps. Results. The total number of procedures included in the analysis was 635. The mean age of the patients was 39±14 years, and 401 of them (63%) were males. The most common location of the APs was left lateral (38%). Procedure time and radiation indices showed a significant decrease over the study period (p < 0.001). Post group procedures had significantly shorter procedure time and lower radiation exposure than pre group procedures. Conclusions. A decrease in the FFR was associated with a significant reduction in radiation exposure in AP ablation procedures

Therapeutic treatment of severe COVID-19 infection involves the administration of multiple pharmacologic agents to reduce the risk of serious complications; this may result in drug interactions and possible adverse reactions and induced cardiotoxicity. The risk–benefit ratio associated with the use of medications to treat COVID-19 should be carefully monitored. In addition, the severe COVID-19 patient may experience cardiac damage, and alteration of normal cardiac electrophysiology function. Severe COVID-19 with cardiac involvement and the risk of drug-induced adverse reactions may cause cardiac arrhythmias, including long qt syndrome, which in some cases may lead to sudden death. In this short review we briefly review the pharmacological agents used to treat severe COVID-19 with increased risk of causing long qt forms.

Aims Accurate determination of intra-atrial conduction velocity (CV) is essential to identify arrhythmogenic areas. The most optimal, commonly used, estimation methodology to measure conduction heterogeneity, including finite differences (FiD), polynomial surface fitting (PSF), and a novel technique using discrete velocity vectors (DVV), has not been determined. We aim (i) to identify the most suitable methodology to unravel local areas of conduction heterogeneities using high-density CV estimation techniques, (ii) to quantify intra-atrial differences in CV, and (iii) to localize areas of CV slowing associated with paroxysmal atrial fibrillation (PAF). Methods and results Intra-operative epicardial mapping (>5000 sites, interelectrode distances 2 mm) of the right and left atrium and Bachmann’s bundle (BB) was performed during sinus rhythm (SR) in 412 patients with or without PAF. The median atrial CV estimated using the DVV, PSF, and FiD techniques was 90.0 (62.4–116.8), 92.0 (70.6–123.2), and 89.4 (62.5–126.5) cm/s, respectively. The largest difference in CV estimates was found between PSF and DVV which was caused by smaller CV magnitudes detected only by the DVV technique. Using DVV, a lower CV at BB was found in PAF patients compared with those without atrial fibrillation (AF) [79.1 (72.2–91.2) vs. 88.3 (79.3–97.2) cm/s; P Conclusions Areas of local conduction heterogeneities were most accurately identified using the DVV technique, whereas PSF and FiD techniques smoothen wavefront propagation thereby masking local areas of conduction slowing. Comparing patients with and without AF, slower wavefront propagation during SR was found at BB in PAF patients, indicating structural remodelling.

BACKGROUND Previous studies have raised serious concerns on cardiovascular safety of widely prescribed nonsteroidal anti-inflammatory drugs (NSAIDs). Therefore, the aim of this study was to characterize the electrophysiological effects of certain NSAIDs in an established whole heart model of proarrhythmia. METHODS AND RESULTS Thirty-eight hearts of New Zealand White rabbits were harvested and retrogradely perfused employing a Langendorff setup, and electrophysiology studies were performed to investigate action potential duration at 90% of repolarization (APD90 ), QT intervals, and effective refractory period (ERP). After generating baseline data, hearts were perfused with ibuprofen (Group 1, n = 12; 10 and 30 μM), indomethacin (Group 2, n = 13; 10 and 20 μM) and diclofenac (Group 3, n = 13; 10 and 20 μM), respectively, and the pacing protocols were repeated for each concentration. In all groups, perfusion with the NSAIDs resulted in a significant and reproducible shortening of APD90 and QT interval. In all groups, the arrhythmia susceptibility was significantly raised as occurrence of monomorphic ventricular tachycardia under programmed ventricular stimulation was significantly increased under perfusion with ibuprofen, indomethacin and diclofenac in all concentrations. CONCLUSION The perfusion with ibuprofen, indomethacin and diclofenac in commonly used doses raised the arrhythmia susceptibility in an established rabbit whole-heart model while APD shortening and shortened ERP seem to be crucial for arrhythmogenesis.

Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.

BACKGROUND Intracardiac electrogram data remain one of the primary diagnostic inputs guiding complex ablation procedures. However, the technology to collect, process, and display intracardiac signals has known shortcomings and has not advanced in several decades. OBJECTIVE The purpose of this study was to evaluate a new signal processing platform, the PURE EP™ system (PURE), in a multi-center, prospective study. METHODS Intracardiac signal data of clinical interest were collected from 51 patients undergoing ablation procedures with PURE, the signal recording system, and the 3D mapping system at the same time stamps. The samples were randomized and subjected to blinded, controlled evaluation by three independent electrophysiologists to determine the overall quality and clinical utility of PURE signals when compared to conventional sources. Each reviewer assessed the same (92) signal sample sets and responded to (235) questions using a 10-point rating scale. If two or more reviewers rated the PURE signal higher than the control, it was deemed superior. RESULTS A total of 93% of question responses showed consensus amongst the blinded reviewers. Based on the ratings for each pair of signals, a cumulative total of 164 PURE signals out of 218 (75.2%) were statistically rated as Superior for this data set (p

PurposeThis review aimed to provide a complete overview of the current stance and recent developments in antiarrhythmic neuromodulatory interventions, focusing on lifethreatening vetricular arrhythmias.MethodsBoth preclinical studies and clinical studies were assessed to highlight the gaps in knowledge that remain to be answered and the necessary steps required to properly translate these strategies to the clinical setting.ResultsCardiac autonomic imbalance, characterized by chronic sympathoexcitation and parasympathetic withdrawal, destabilizes cardiac electrophysiology and promotes ventricular arrhythmogenesis. Therefore, neuromodulatory interventions that target the sympatho-vagal imbalance have emerged as promising antiarrhythmic strategies. These strategies are aimed at different parts of the cardiac neuraxis and directly or indirectly restore cardiac autonomic tone. These interventions include pharmacological blockade of sympathetic neurotransmitters and neuropeptides, cardiac sympathetic denervation, thoracic epidural anesthesia, and spinal cord and vagal nerve stimulation.ConclusionNeuromodulatory strategies have repeatedly been demonstrated to be highly effective and very promising anti-arrhythmic therapies. Nevertheless, there is still much room to gain in our understanding of neurocardiac physiology, refining the current neuromodulatory strategic options and elucidating the chronic effects of many of these strategic options.

Background Interatrial septal tachycardias (IAS-ATs) following atrial fibrillation (AF) ablation or cardiac surgery are rare, and their management is challenging. Objective The purpose of this study was to investigate the electrophysiological features and outcomes associated with catheter ablation of IAS-AT. Methods We screened 338 patients undergoing catheter ablation of ATs following AF ablation or cardiac surgery. Diagnosis of IAS-AT was based on activation mapping and analysis of response to atrial overdrive pacing. Results Twenty-nine patients (9%) had IAS-AT (cycle length [CL] 311 ± 104 ms); 16 (55%) had prior AF ablation procedures (median 3; range 1–5), 3 (10%) had prior surgical maze, and 12 (41%) had prior cardiac surgery (including atrial septal defect surgical repair in 5 and left atrial myxoma resection in 1). IAS substrate abnormalities were documented in all patients. Activation mapping always demonstrated a diffuse early IAS breakout with centrifugal biatrial activation, and atrial overdrive pacing showed a good postpacing interval (equal or within 25 ms of the AT CL) only at 1 or 2 anatomically opposite IAS sites in all cases. Ablation was acutely successful in 27 patients (93%) (from only the right IAS in 2, only the left IAS in 9, both IAS sides with sequential ablation in 13, and both IAS sides with bipolar ablation in 3). After median follow-up of 15 (6–52) months, 17 patients (59%) remained free from recurrent arrhythmias. Conclusion IAS-ATs are rare and typically occur in patients with evidence of IAS substrate abnormalities and prior cardiac surgery. Catheter ablation can be challenging and may require sequential unipolar ablation or bipolar ablation.

Spurred by federal legislation, professional organizations, and patients themselves, patient access to data from electronic cardiac devices is increasingly transparent. Patients can collect data through consumer devices and access data traditionally shared only with health care providers. These data may improve screening, self-management, and shared decision-making for cardiac arrhythmias, but challenges remain, including patient comprehension, communication with providers, and sustained engagement. Ways to address these challenges include leveraging visualizations that support comprehension, involving patients in designing and developing patient-facing digital tools, and establishing clear practices and goals for data exchange with health care providers.

The coronavirus disease 2019 (COVID-19) pandemic has resulted in a deep restructuring of cardiovascular care, especially in the setting of cardiac arrhythmia units, which are characterized by a wide variety of clinical and interventional activities. We describe the experience of a large university hospital deeply hit during the COVID-19 health crisis (first outbreak of the pandemic), focusing on the exceptional measures implemented and their impact in terms of outcomes. We performed a retrospective study comparing the human and structural resources and the activity of a cardiac arrhythmia unit in a Spanish tertiary hospital for two consecutive periods: from January 12, 2020, to March 8, 2020 (“pre-COVID stage”), and from March 9, 2020, to May 2, 2020 (“COVID stage”). Data were contextualized within the number of confirmed COVID-19 cases in the region of Madrid. The measures implemented were promotion of non–face-to-face consultations, selection of urgent procedures, design of a “COVID-free” circuit for outpatient interventions, and protocolization for patients with COVID-19. A total of 3,526 consultations and 362 procedures were performed. During the COVID stage, the number of consultations remained stable, and the electrophysiology rooms’ activity decreased by 55.2% with a relative increase in the number of urgent-hospitalized cases attended (11.8% COVID-19-positive patients). The electrophysiology rooms’ activity returned to “normal” in the last week of the COVID stage, with no contagion being detected among patients or professionals. In conclusion, the measures implemented allowed us to respond safely and efficiently to the health care needs of patients with arrhythmias during the COVID-19 crisis and may be useful for other institutions facing similar situations.

Paediatric atrial fibrillation (AF) is an infrequent entity in the absence of congenital heart disease as children are unlikely to have the structural and functional changes in their myocardium to sustain the arrhythmia. Any child presenting with this arrhythmia needs to be carefully evaluated for concealed cardiac pathology such as cardiomyopathy or inherited arrhythmia syndromes. AF leading to a haemodynamically unstable patient is rare and should prompt synchronised cardioversion, while stable patients can be discussed with a paediatric cardiologist. Tachycardia-induced cardiomyopathy and thromboembolism are possible complications of sustained AF and anticoagulation is usually indicated to prevent the latter. Risk of AF increases with age and body mass index. Obesity and athletics are known risk factors and recurrence can be seen even in the absence of any identifiable underlying pathology.

The field of cardiac electrophysiology (EP) had adopted simple artificial intelligence (AI) methodologies for decades. Recent renewed interest in deep learning techniques has opened new frontiers in electrocardiography analysis including signature identification of diseased states. Artificial intelligence advances coupled with simultaneous rapid growth in computational power, sensor technology, and availability of web-based platforms have seen the rapid growth of AI-aided applications and big data research. Changing lifestyles with an expansion of the concept of internet of things and advancements in telecommunication technology have opened doors to population-based detection of atrial fibrillation in ways, which were previously unimaginable. Artificial intelligence-aided advances in 3D cardiac imaging heralded the concept of virtual hearts and the simulation of cardiac arrhythmias. Robotics, completely non-invasive ablation therapy, and the concept of extended realities show promise to revolutionize the future of EP. In this review, we discuss the impact of AI and recent technological advances in all aspects of arrhythmia care., Graphical Abstract Artificial intelligence-enhanced arrhythmia care.

Possible mechanisms of left-axis deviation (LAD) in the setting of left bundle branch block (LBBB) include differences in cardiac electrophysiology, structure, or anatomic axis.The purpose of this study was to clarify the mechanism(s) responsible for LAD in patients with LBBB.Twenty-nine patients with nonischemic cardiomyopathies and LBBB underwent noninvasive electrocardiographic imaging (ECGi), cardiac computed tomography, and magnetic resonance imaging in order to define ventricular electrical activation, characterize cardiac structure, and determine the cardiac anatomic axis.Sixteen patients had a normal QRS axis (NA) (mean axis 8° ± 23°), whereas 13 patients had LAD (mean axis -48° ± 13°; P.001). Total activation times were longer in the LAD group (112 ± 25 ms vs 91 ± 14 ms; P = .01) due to delayed activation of the basal anterolateral region (107 ± 10 ms vs 81 ± 17 ms; P .001). Left ventricular (LV) activation in patients with LAD was from apex to base, in contrast to a circumferential pattern of activation in patients with NA. Apex-to-base delay was longer in the LA group (95 ± 13 ms vs 64 ± 21 ms; P.001) and correlated with QRS frontal axis (RLAD in LBBB appears to be due to electrophysiological abnormalities rather than structural factors or cardiac anatomic axis.

Background Implantable cardioverter-defibrillators (ICDs) are an effective treatment in some patients with inherited heart disease, including inherited channelopathies, yet they have also been shown to impact patients' psychological health. Objective We sought to improve understanding of the level of anxiety and depression as well as device acceptance among inherited channelopathy patients with an ICD. Methods Eligible patients seen at Johns Hopkins Hospital were sent a survey, which included the Hospital Anxiety and Depression Scale (HADS), Cardiac Anxiety Questionnaire (CAQ), and the Florida Patient Acceptance Survey (FPAS). Student t tests and χ2 tests were used to identify associations with abnormal anxiety and depression scores. Results Among eligible patients (n = 65), 32 individuals (49%) completed the survey. The rate of device-related complications was 34%, and 41% of patients experienced 1 or more ICD shocks. Twelve patients (38%) had an abnormal HADS anxiety subscore and 5 patients (16%) had an abnormal HADS depression subscore (score ≥ 8). Secondary-prevention ICDs were associated with an abnormal HADS anxiety subscore (P = .03). Experiencing ICD shock(s), device complications, age, sex, and family history of sudden cardiac death were not statistically associated with anxiety or depression. Overall, respondents demonstrated high device acceptance by FPAS (79.9 ± 2.9, maximum total score 100) and moderately high cardiac-specific anxiety by CAQ total score (1.53 ± 0.12). Conclusion A high prevalence of generalized anxiety was identified among inherited channelopathy patients with ICDs. High device acceptance and lack of association with ICD shocks or complications indicate that further research is necessary to understand this increased incidence.

Background Inhomogeneity of ventricular contraction is associated with sudden cardiac death, but the underlying mechanisms are unclear. Alterations in cardiac contraction impact electrophysiological parameters through mechanoelectric feedback. This has been shown to promote arrhythmias in experimental studies, but its effect in the in vivo human heart is unclear. Objective The purpose of this study was to quantify the impact of regional myocardial deformation provoked by a sudden increase in ventricular loading (aortic occlusion) on human cardiac electrophysiology. Methods In 10 patients undergoing open heart cardiac surgery, left ventricular (LV) afterload was modified by transient aortic occlusion. Simultaneous assessment of whole-heart electrophysiology and LV deformation was performed using an epicardial sock (240 electrodes) and speckle-tracking transesophageal echocardiography. Parameters were matched to 6 American Heart Association LV model segments. The association between changes in regional myocardial segment length and activation-recovery interval (ARI; a conventional surrogate for action potential duration) was studied using mixed-effect models. Results Increased ventricular loading reduced longitudinal shortening (P = .01) and shortened ARI (P = .02), but changes were heterogeneous between cardiac segments. Increased regional longitudinal shortening was associated with ARI shortening (effect size 0.20 [0.01–0.38] ms/%; P = .04) and increased local ARI dispersion (effect size –0.13 [–0.23 to –0.03] ms/%; P = .04). At the whole organ level, increased mechanical dispersion translated into increased dispersion of repolarization (correlation coefficient r = 0.81; P = .01). Conclusion Mechanoelectric feedback can establish a potentially proarrhythmic substrate in the human heart and should be considered to advance our understanding and prevention of cardiac arrhythmias.

Perfect adherence to anticoagulant medications is an important aspect of care for patients with atrial fibrillation undergoing cardiac electrophysiology procedures to minimize the risk of stroke. Despite this, adherence remains imperfect as is associated with added cost of additional procedures (e.g., transesophageal echocardiography) and administrative burden. We sought to identify characteristics of such patients and predictors of medication errors at Beth Israel Deaconess Medical Center. Cardiol Res. 2021;12(4):265-268 doi: https://doi.org/10.14740/cr1266

Cardiac arrhythmias are a major cause of death and disability. A large number of experimental cell and animal models have been developed to study arrhythmogenic diseases. These models have provided important insights into the underlying arrhythmia mechanisms and translational options for their therapeutic management. This position paper from the ESC Working Group on Cardiac Cellular Electrophysiology provides an overview of (i) currently available in vitro, ex vivo, and in vivo electrophysiological research methodologies, (ii) the most commonly used experimental (cellular and animal) models for cardiac arrhythmias including relevant species differences, (iii) the use of human cardiac tissue, induced pluripotent stem cell (hiPSC)-derived and in silico models to study cardiac arrhythmias, and (iv) the availability, relevance, limitations, and opportunities of these cellular and animal models to recapitulate specific acquired and inherited arrhythmogenic diseases, including atrial fibrillation, heart failure, cardiomyopathy, myocarditis, sinus node, and conduction disorders and channelopathies. By promoting a better understanding of these models and their limitations, this position paper aims to improve the quality of basic research in cardiac electrophysiology, with the ultimate goal to facilitate the clinical translation and application of basic electrophysiological research findings on arrhythmia mechanisms and therapies.

With a growing acceptance of clinical hypnosis in medicine, new fields of application are being explored. Data from recent studies support the use of hypnosis for pain management during procedures, such as ablation of arrhythmias and implantation of subcutaneous implantable cardioverter defibrillators, management of preoperative anxiety and reduction of postoperative atrial fibrillation. The aim of this review article is to summarize the findings of investigations showing the application of hypnosis in the field of cardiac electrophysiology, to review the rationale for the efficacy of hypnosis in management of cardiac arrhythmias and to highlight possible future directions in clinical applications and scientific perspectives.

Leadless cardiac pacemakers were developed to reduce complications associated with conventional transvenous pacemakers. While this technology is still relatively new, devices are increasingly being implanted. The perioperative management of patients with these devices has been underreported; we thus seek to add to the limited body of knowledge of perioperative management of patients with leadless cardiac pacemakers. An elderly female patient with a Micra VR transcatheter pacing system leadless cardiac pacemaker placed for tachycardia-bradycardia syndrome with intermittent complete heart block was scheduled for elective tricuspid valve replacement for severe tricuspid regurgitation. Pacemaker interrogation was performed several hours prior to the scheduled surgery based on the electrophysiologist’s availability; the device was kept in its programmed VVIR mode, and the base rate was increased from 60 to 80 beats per minute in anticipation of the upcoming surgery. Upon preoperative evaluation, the anesthesiologist asked that the electrophysiology team be placed on standby intraoperatively due to the concern that either oversensing in the setting of pacemaker dependence and/or undesirable tachycardia from rate-responsive pacing could occur. The surgeon used monopolar electrocautery for the duration of the cardiac surgery. Despite the patient having evidence of pacemaker dependence in the intensive care unit preoperatively, no electromagnetic interference leading to oversensing nor rate modulation was detected during intraoperative electrocardiographic and intraarterial invasive monitoring. Evidence-based guidelines regarding perioperative management specifically of leadless cardiac pacemakers do not exist. As these devices become more prevalent, further evaluation will be paramount to determine whether existing guidelines for perioperative management of conventional transvenous pacemakers apply.

Aufgrund guter Ergebnisse, zunehmender Standardisierung und Fehlen von gleichwertigen Alternativen gehort die Durchfuhrung einer Katheterablation zunehmend zum klinischen Alltag vieler Kliniken. Dieser Artikel beschreibt die Durchfuhrung haufiger oder notwendiger Punktionen (Punktion der Leistengefase, transseptale Punktion, Perikardpunktion) im Rahmen einer Katheterablation und soll eine praktische Anleitung fur die Arbeit im Herzkatheterlabor darstellen. Diese Arbeit setzt eine Reihe von Artikeln fort, die fur eine Weiterbildung im Bereich der speziellen Rhythmologie konzipiert sind.

It is increasingly recognized that the autonomic nervous system (ANS) is a major contributor in many cardiac arrhythmias. Cardiac ANS can be divided into extrinsic and intrinsic parts according to the course of nerve fibers and localization of ganglia and neuron bodies. Although the role of the extrinsic part has historically gained more attention, the intrinsic cardiac ANS may affect cardiac function independently as well as influence the effects of the extrinsic nerves. Catheter-based modulation of the intrinsic cardiac ANS is emerging as a novel therapy for the management of patients with brady and tachyarrhythmias resulting from hyperactive vagal activation. However, the distribution of intrinsic cardiac nerve plexus in the human heart and the functional properties of intrinsic cardiac neural elements remain insufficiently understood. The present review aims to bring the clinical and anatomical elements of the immune effector cell-associated neurotoxicity together, by reviewing neuroanatomical terminologies and physiological functions, to guide the clinical electrophysiologist in the catheter lab and to serve as a reference for further research.

Left ventricular assist device implantation is a recognized treatment option for patients with advanced heart failure refractory to medical therapy and can be used both as bridge to transplantation and as destination therapy. The risk of ventricular arrhythmias is common after left ventricular assist device implantation and is influenced by pre‐, peri and post‐operative determinants. The management of ventricular arrhythmias can be a challenge when they become refractory to medication or to device therapy and their impact on prognosis can be detrimental despite the mechanical support. In this setting, catheter ablation is being increasingly recognized as a feasible option for patients in which standard therapeutic strategies fail, but also with preventive purpose. Catheter ablation is being increasingly considered for the management of ventricular arrhythmias in patients with left ventricular assist device despite complex clinical and technical peculiarities due to the characteristics of the mechanical support. Much conflicting data exist regarding the predictors of success of the procedure and the rate of recurrence. In this review we discuss the latest evidences regarding catheter ablation of ventricular arrhythmias in this subset of patients, focusing on clinical characteristics, arrhythmia etiology, technical aspects and postprocedural features which must be considered by the electrophysiologist., Ventricular arrythmias have a significant prognostic impact in patients with LVAD. Catheter ablation in patients with LVAD is a feasible option when first line therapy fails. Mapping can be challenging due to mechanical and electromagnetic limitations. Complications can be reduced through a careful pre‐procedural planning.

У людей похилого віку виникають зміни в тканинах міокарду і провідній системі серця, що призводить до підвищення поширеності різних видів порушень серцевого ритму.

Despite significant advances in its detection, understanding and management, atrial fibrillation (AF) remains a highly prevalent cardiac arrhythmia with a major impact on morbidity and mortality of millions of patients. AF results from complex, dynamic interactions between risk factors and comorbidities that induce diverse atrial remodelling processes. Atrial remodelling increases AF vulnerability and persistence, while promoting disease progression. The variability in presentation and wide range of mechanisms involved in initiation, maintenance and progression of AF, as well as its associated adverse outcomes, make the early identification of causal factors modifiable with therapeutic interventions challenging, likely contributing to suboptimal efficacy of current AF management. Computational modelling facilitates the multilevel integration of multiple datasets and offers new opportunities for mechanistic understanding, risk prediction and personalized therapy. Mathematical simulations of cardiac electrophysiology have been around for 60 years and are being increasingly used to improve our understanding of AF mechanisms and guide AF therapy. This narrative review focuses on the emerging and future applications of computational modelling in AF management. We summarize clinical challenges that may benefit from computational modelling, provide an overview of the different in silico approaches that are available together with their notable achievements, and discuss the major limitations that hinder the routine clinical application of these approaches. Finally, future perspectives are addressed. With the rapid progress in electronic technologies including computing, clinical applications of computational modelling are advancing rapidly. We expect that their application will progressively increase in prominence, especially if their added value can be demonstrated in clinical trials., Graphical Abstract

Social media (SoMe) becomes more and more popular in the cardiological community. Among them, Twitter is an emerging and dynamic medium to connect, communicate and educate academic and clinical cardiologists. However, in contrast to traditional scientific communications, the content provided through SoMe is not peer-reviewed and may not necessarily always represent scientific evidence or may even be used to unjustifiably promote therapies for commercial purposes. For the unintended, this means of communication might be appear difficult to handle. This article aims to provide a practical guide on how to use Twitter efficiently for professional use to keep yourself up-to-date about new techniques, the latest study results and news presented at national or international conferences. Additionally, important limitations will be discussed.

Ablation treatment for persistent atrial fibrillation (persAF) remains challenging due to the absence of a 'ground truth' for atrial substrate characterization and the presence of multiple mechanisms driving the arrhythmia. We implemented an unsupervised classification to identify clusters of atrial electrograms (AEGs) with similar patterns, which were then validated by AEG-derived markers.956 bipolar AEGs were collected from 11 persAF patients. CARTO variables (Biosense Webster; ICL, ACI and SCI) were used to create a 3D space, and subsequently used to perform an unsupervised classification with k-means. The characteristics of the identified groups were investigated using nine AEG-derived markers: sample entropy (SampEn), dominant frequency, organization index (OI), determinism, laminarity, recurrence rate (RR), peak-to-peak (PP) amplitude, cycle length (CL), and wave similarity (WS).Five AEG classes with distinct characteristics were identified (F = 582, P0.0001). The presence of fractionation increased from class 1 to 5, as reflected by the nine markers. Class 1 (25%) included organized AEGs with high WS, determinism, laminarity, and RR, and low SampEn. Class 5 (20%) comprised fractionated AEGs with in low WS, OI, determinism, laminarity, and RR, and in high SampEn. Classes 2 (12%), 3 (13%) and 4 (30%) suggested different degrees of AEG organization.Our results expand and reinterpret the criteria used for automated AEG classification. The nine markers highlighted electrophysiological differences among the five classes found by the k-means, which could provide a more complete characterization of persAF substrate during ablation target identification in future clinical studies.

Patients with heart disease, or at high risk of developing a cardiac condition, usually undergo risk assessment by primary care physicians, internal medicine doctors, or cardiologists. There are several methods that can be used for this risk assessment, and their applicability differs with respect to availability, complexity, and usefulness in different geographic populations. This document focuses on some of the many relevant clinical topics recently presented in the "Expert Consensus on Risk Assessment in Cardiac Arrhythmias: Use the Right Tool for the Right Outcome," which include statements based on the best available evidence. In this review, we want to highlight and make some pertinent comments on some of the most relevant points of this Consensus.

Aims Non-invasive imaging of electrical activation requires high-density body surface potential mapping. The nine electrodes of the 12-lead electrocardiogram (ECG) are insufficient for a reliable reconstruction with standard inverse methods. Patient-specific modelling may offer an alternative route to physiologically constraint the reconstruction. The aim of the study was to assess the feasibility of reconstructing the fully 3D electrical activation map of the ventricles from the 12-lead ECG and cardiovascular magnetic resonance (CMR). Methods and results Ventricular activation was estimated by iteratively optimizing the parameters (conduction velocity and sites of earliest activation) of a patient-specific model to fit the simulated to the recorded ECG. Chest and cardiac anatomy of 11 patients (QRS duration 126–180 ms, documented scar in two) were segmented from CMR images. Scar presence was assessed by magnetic resonance (MR) contrast enhancement. Activation sequences were modelled with a physiologically based propagation model and ECGs with lead field theory. Validation was performed by comparing reconstructed activation maps with those acquired by invasive electroanatomical mapping of coronary sinus/veins (CS) and right ventricular (RV) and left ventricular (LV) endocardium. The QRS complex was correctly reproduced by the model (Pearson’s correlation r = 0.923). Reconstructions accurately located the earliest and latest activated LV regions (median barycentre distance 8.2 mm, IQR 8.8 mm). Correlation of simulated with recorded activation time was very good at LV endocardium (r = 0.83) and good at CS (r = 0.68) and RV endocardium (r = 0.58). Conclusion Non-invasive assessment of biventricular 3D activation using the 12-lead ECG and MR imaging is feasible. Potential applications include patient-specific modelling and pre-/per-procedural evaluation of ventricular activation.

Following demonstration that the intrinsic cardiac nervous system (ICNS) is a potential modulator of the initiation and perpetuation of atrial fibrillation and the major reason for several bradyarrhythmias, catheter-based autonomic modulation emerged as a novel therapy in recent years (1,2). The anatomy and physiology of the ICNS are relevant to the cardiac electrophysiologist because this invisible anatomic structure is becoming an important target during radiofrequency catheter ablation.

A substantial number of pregnant women at some point experience cardiac arrhythmia, which is mostly treated by antiarrhythmic medication. In some instances, arrhythmias can be drug-resistant and pose a relevant risk to both mother and unborn child as they can result in hemodynamic compromise. In recent years, invasive electrophysiology procedures have been carried out with ever reducing exposure to ionising radiation, and multiple techniques have been established to achieve ZERO exposure. Of course, these techniques should all be applied when contemplating an invasive mapping and ablation procedure during pregnancy. The role of the cardio-obstetrics team in planning and performing such procedures is paramount. Careful assessment of the pregnant mother and her unborn child is mandatory. Only with good preparation is a complete understanding of both cardiac anatomy and physiology achievable, which is a pre-requisite of a successful ablation outcome. Various aspects of the ablation procedure itself are discussed and evaluated from the perspective of all team members involved, including the obstetrician, the anaesthetist and the electrophysiologist. This review aims to inform the reader about the techniques available and reports on the published outcomes for ablations during pregnancy in the last decade.

Aims This report describes the findings of the 2018 Italian Catheter Ablation Registry of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC). Methods The Italian Catheter Ablation Registry systematically collects data on the ablation procedures performed in Italy. Data collection was retrospective. A standardized questionnaire was completed by participating centres. Results We collected data on 15 714 catheter ablation procedures performed in Italy during 2018 in 94 electrophysiology centres. In most centres (75/94, 80%), a single electrophysiology laboratory was available, and a hybrid electrophysiology laboratory was available in 15% (14/94) of centres. In most (93%) centres, at least two electrophysiologists were involved in the catheter ablation procedures. In only 13 out of 94 (14%) electrophysiology laboratories, an anaesthesiologist assists every electrophysiology procedure; in most cases (74/94, 79%), an on-demand anaesthesiology service was available. On-site cardiothoracic surgery was reported in 43 out of 94 (46%) centres.Nonfluoroscopic navigation systems were available in most centres (88/94, 93%). Intracardiac echocardiography was used in 59 out of 94 (63%) electrophysiology laboratories. Atrial fibrillation (31%) was the most frequently treated ablation target, followed by atrioventricular nodal re-entrant tachycardia (20%) and cavo-tricuspid isthmus (15%). In 61.7% of all procedures, a 3D mapping system was used. In about one-third of procedures, a near-zero approach was performed. Conclusion In most Italian electrophysiology centres, a single electrophysiology laboratory was available and at least two electrophysiologists were involved in the ablation procedures. An increasing number of procedures were performed by means of a nonfluoroscopic mapping system with a near-zero approach.

Chagas disease is caused by infection from the protozoan parasite Trypanosoma cruzi. Although it is endemic to Latin America, global migration has led to an increased incidence of Chagas in Europe, Asia, Australia, and North America. Following acute infection, up to 30% of patients will develop chronic Chagas disease, with most patients developing Chagasic cardiomyopathy. Chronic Chagas cardiomyopathy is highly arrhythmogenic, with estimated annual rates of appropriate implantable cardioverter-defibrillator therapies and electrical storm of 25% and 9.1%, respectively. Managing arrhythmias in patients with Chagasic cardiomyopathy is a major challenge for the clinical electrophysiologist, requiring intimate knowledge of cardiac anatomy, advanced training, and expertise. Endocardial-epicardial mapping and ablation strategy is needed to treat arrhythmias in this patient population, owing to the suboptimal long-term success rate of endocardial mapping and ablation alone. We also describe innovative approaches to improve acute and long-term clinical outcomes in patients with refractory ventricular arrhythmias following catheter ablation, such as bilateral cervicothoracic sympathectomy and bilateral renal denervation, among others.

Background The heart rate increases by 10–20 beats per minute (bpm) throughout pregnancy in women, reaching maximum heart rate in the third trimester. During pregnancy, important changes in thyroid hormones also occur, with increases of up to 50% in the levels of triiodothyronine (T3), the biological active thyroid hormone. In addition, T3 has been shown to regulate cardiac electrophysiology. Objective Thus, in the present study the potential contribution of T3 in pregnancy-induced increased heart rate was explored. Methods We compared the heart rate between nonpregnant and pregnant mice under control conditions and after altering thyroid hormone levels with T3 and propylthiouracil (PTU, an antithyroid drug) treatments. Results Consistent with the clinical data, we found a 58% rise in T3 levels during pregnancy in mice. Although pregnant mice had a higher baseline heart rate (607 ± 8 bpm, P = .004) and higher T3 levels (1.9 ± 0.4 nM, P = .0005) than nonpregnant mice (heart rate: 546 ± 16 bpm; T3 levels: 1.2 ± 0.1 nM), their heart rate responded similarly to T3 treatment as nonpregnant mice (nonpregnant: Δ130 ± 22 bpm; pregnant: Δ126 ± 17 bpm, P = .858). Additionally, the heart rate remained significantly elevated (607 ± 11 bpm, P = .038) and comparable to untreated pregnant mice, after the use of the antithyroid drug PTU, although T3 levels (1.3 ± 0.2 nM, P = .559) returned to nonpregnant values. Conclusion Based on these results, it is unlikely that T3 contributes significantly to the pregnancy-induced increased heart rate.

Introduction: The authors present the results of the national cardiac electrophysiology registry of the Portuguese Association of Arrhythmology, Pacing and Electrophysiology (APAPE) and the Portuguese Institute of Cardiac Rhythm (IPRC) for 2017 and 2018. Methods: The registry is annual, voluntary, and observational. Data are collected retrospectively. Developments over the years and their implications are analyzed and discussed. Results: In the 22 electrophysiology centers, 3407 ablations were performed in 2017 and 3653 ablations in 2018. Atrial fibrillation (AF) ablation was the most frequently performed procedure: 1017 ablations in 2017 and 1222 procedures in 2018. Of the patients undergoing AF ablation, 63% were male, 60% were between 50 and 69 years old and 74% had paroxysmal AF. Clinically relevant complications were reported in 0.8% of the procedures. In 2017, 216 ventricular tachycardia or ventricular fibrillation (VT/VF) ablation procedures were performed in 15 centers. In 2018, 19 centers performed 249 TV/VF ablations. About 45% of VT/VF ablations were performed in patients with structural heart disease. Complications were reported in 3.2% of the procedures, including one death (0.2%). Conclusions: The national electrophysiology registry showed a sustained increase in the number of catheter ablations. In addition, procedural complexity increased and AF ablation assumed a dominant position among the procedures performed. Resumo: Objetivo: Apresentam-se os dados referentes ao Registo Nacional de Eletrofisiologia Cardíaca da Associação Portuguesa de Arritmologia, Pacing e Eletrofisiologia (APAPE) e Instituto Português do Ritmo Cardíaco (IPRC) para os anos de 2017 e 2018. Métodos: Trata-se de um registo anual, voluntário, observacional e retrospetivo. É analisada a evolução da atividade dos Centros de Eletrofisiologia tendo em conta o tipo de procedimentos realizados e são discutidas as potenciais implicações. Resultados: Nos 22 Centros de Eletrofisiologia em funcionamento foram realizadas 3407 ablações em 2017 e 3653 ablações em 2018. A ablação de fibrilhação auricular foi o procedimento mais frequente (1017 ablações em 2017 e 1222 em 2018). Dos doentes submetidos a ablação de fibrilhação auricular, 63% eram do sexo masculino, 60% apresentavam entre 50 e 69 anos de idade e 74% tinham arritmia paroxística. Foram reportadas complicações clinicamente relevantes em 0,8% dos procedimentos.Em 2017, foram efetuadas 216 ablações de taquicardia ventricular ou fibrilhação ventricular (TV/FV) em 15 centros. Em 2018, 19 centros realizaram 249 ablações de TV/FV. Cerca de 45% das ablações de TV/FV foram efetuadas em doentes com cardiopatia estrutural. Foram reportadas complicações em 3,2% dos procedimentos, incluindo um óbito (0,2%). Conclusão: A eletrofisiologia nacional mantém um crescimento no número de ablações por cateter. Além disso, verificou-se aumento na complexidade das ablações realizadas, assumido a ablação de fibrilhação auricular uma posição dominante entre os procedimentos efetuados.

Left bundle branch pacing (LBBP) has been adopted as a new pacing therapy whether in routine pacing or patients with heart failure, but the criteria for a completely captured LBBP are too complicated and have a low success rate in routine clinical practice.Consecutive patients with pacing therapy indications were enrolled. Left bundle branch area pacing (LBBAP) was conducted, and the presence of LBB potential, paced QRS duration, stimulus to left ventricular activation time (Stim-LVAT), and LBB potential to left ventricular activation time (LBB po-LVAT) were determined and utilized to characterize LBBAP modalities. Pacing parameters and safety were assessed at 6-month follow-up. LBBAP succeeded in 95.6% of patients (103/106) who completed the 6-month follow-up. Complete LBBP was achieved in 21 (20%) patients, characterized with a short Stim-LVAT equal to LBB po-LVAT. Incomplete LBBP was achieved in 58 (56%) patients with a short Stim-LVAT equal to LBB po-LVAT at a high pacing output and a relatively longer Stim-LVAT at a low pacing output. Deep septal pacing (DSP) characterized with no LBB potential and a longer Stim-LVAT (83.3 ± 7.7 ms) than that in LBBP (71.37 ± 7.1 ms, P < 0.01 versus DSP) was observed in 24 (23%) patients. Complete LBBP had a longer total procedure time and longer fluoroscopic time than the other two groups.This study describes the similarities and differences in electrophysiological characteristics and the possible mechanisms of the different types of LBBAP, classified into 3 modalities in routine clinical practice, each with narrow paced QRS duration and stable parameters, indicating LBBAP can be a near-physiological pacing modality.

Aims Diabetic hyperglycaemia is associated with increased arrhythmia risk. We aimed to investigate whether hyperglycaemia alone can be accountable for arrhythmias or whether it requires the presence of additional pathological factors. Methods and results Action potentials (APs) and arrhythmogenic spontaneous diastolic activities were measured in isolated murine ventricular, rabbit atrial, and ventricular myocytes acutely exposed to high glucose. Acute hyperglycaemia increased the short-term variability (STV) of action potential duration (APD), enhanced delayed afterdepolarizations, and the inducibility of APD alternans during tachypacing in both murine and rabbit atrial and ventricular myocytes. Hyperglycaemia also prolonged APD in mice and rabbit atrial cells but not in rabbit ventricular myocytes. However, rabbit ventricular APD was more strongly depressed by block of late Na+ current (INaL) during hyperglycaemia, consistent with elevated INaL in hyperglycaemia. All the above proarrhythmic glucose effects were Ca2+-dependent and abolished by CaMKII inhibition. Importantly, when the repolarization reserve was reduced by pharmacological inhibition of K+ channels (either Ito, IKr, IKs, or IK1) or hypokalaemia, acute hyperglycaemia further prolonged APD and further increased STV and alternans in rabbit ventricular myocytes. Likewise, when rabbit ventricular myocytes were pretreated with isoproterenol or angiotensin II, hyperglycaemia significantly prolonged APD, increased STV and promoted alternans. Moreover, acute hyperglycaemia markedly prolonged APD and further enhanced STV in failing rabbit ventricular myocytes. Conclusion We conclude that even though hyperglycaemia alone can enhance cellular proarrhythmic mechanisms, a second hit which reduces the repolarization reserve or stimulates G protein-coupled receptor signalling greatly exacerbates cardiac arrhythmogenesis in diabetic hyperglycaemia.

Aims Genetically altered mice are powerful models to investigate mechanisms of atrial arrhythmias, but normal ranges for murine atrial electrophysiology have not been robustly characterized. Methods and results We analyzed results from 221 electrophysiological (EP) studies in isolated, Langendorff-perfused hearts of wildtype mice (114 female, 107 male) from 2.5 to 17.7 months (mean 7 months) with different genetic backgrounds (C57BL/6, FVB/N, MF1, 129/Sv, Swiss agouti). Left atrial monophasic action potential duration (LA-APD), interatrial activation time (IA-AT), and atrial effective refractory period (ERP) were summarized at different pacing cycle lengths (PCLs). Factors influencing atrial electrophysiology including genetic background, sex, and age were determined. LA-APD70 was 18 ± 0.5 ms, atrial ERP was 27 ± 0.8 ms, and IA-AT was 17 ± 0.5 ms at 100 ms PCL. LA-APD was longer with longer PCL (+17% from 80 to 120 ms PCL for APD70), while IA-AT decreased (−7% from 80 to 120 ms PCL). Female sex was associated with longer ERP (+14% vs. males). Genetic background influenced atrial electrophysiology: LA-APD70 (−20% vs. average) and atrial ERP (−25% vs. average) were shorter in Swiss agouti background compared to others. LA-APD70 (+25% vs. average) and IA-AT (+44% vs. average) were longer in 129/Sv mice. Atrial ERP was longer in FVB/N (+34% vs. average) and in younger experimental groups below 6 months of age. Conclusion This work defines normal ranges for murine atrial EP parameters. Genetic background has a profound effect on these parameters, at least of the magnitude as those of sex and age. These results can inform the experimental design and interpretation of murine atrial electrophysiology.

Fetal cardiac monitoring is one of the cornerstones of modern obstetric care. Noninvasive fetal electrocardiography (NI-FECG) is an emerging modality for monitoring fetal well-being using electrical signals recorded from the maternal abdomen. However, the reliability of NI-FECG extraction techniques remains highly variable due to a range of technical and clinical factors, such as sensor placement and interindividual anatomic variations. In this work, we propose, develop, and validate an open-source method for modeling these variations, including changes in maternal body structure and fetal position using two clinical NI-FECG databases. To validate our model’s accuracy, we first assess its performance in characterizing the fetal QRS (fQRS) complex amplitude in six private NI-FECG recordings with detailed anatomic information. To demonstrate its clinical utility, we next apply our model to predict an optimal sensor placement in a separate open-access database of 60 24-channel NI-FECG recordings. The optimal six sensor positions predicted by our model achieve similar reliability for fetal heart rate (FHR) monitoring compared to the entire 24-sensor array. The presented results indicate our model provides a suitable method for estimating the influence of anatomic variations on NI-FECG signals and optimizing sensor placement in a simulated setting. The code for the developed model has been made available under an open-source GPL license and contributed to the fecgsyn toolbox.

Introduction A significant improvement in safety and efficacy of ablation for paroxysmal atrial fibrillation (PAF) has been reported by experienced centers over recent years; however, data from real-life surveys and smaller electrophysiology (EP) laboratories have been less optimistic. Aim To asses efficacy of ablation for PAF in a middle-volume EP center over last years. Methods Retrospective analysis of 1 year efficacy and safety of ablation for PAF in three cohorts of patients treated between 2011 and 2014 (period I), 2015–2017 (period II), and 2018–2019 (period III). Results Of 234 patients (mean age 57 ± 9 years, 165 males), 81 (35%) were treated in period I, 84 (36%) in period II, and 69 (29%) in period III. The overall efficacy of ablation during all analyzed periods was 67%. The overall efficacy of ablation increased over time—from 56% in period I to 68% in period II and 81% in period III. Significant improvement was achieved using radiofrequency ablation (RF) (53% in period I vs 82% in period III, and 55% in period II vs 82% in period III, p = 0.003 and 0.0012, respectively) whereas positive trend in the improvement of cryoballoon efficacy was NS. The rate of peri-procedural complications was 9% and it did not change significantly over time. Conclusions This real-life observational study from a medium volume EP center shows that progress in PAF ablation, especially RF, reported by highly-skilled centers, can be reproduced in real life by less experienced operators.

Medicine has many great pioneers, and in 1899, one such pioneer - Karel Frederik Wenckebach made a discovery which, even to this day, remains one of the fundamental concepts within electrophysiology. : Since the Wenckebach Phenomenon was first described, the field of electrophysiology has developed at a rapid pace, allowing us to observe this behaviour, and its complexities, in many new ways. In a similar way, this chapter will illustrate Wenckebach behaviour across a spectrum of modalities from the 12 lead ECG, through to the intra-cardiac recordings from both electrophysiological studies and implantable cardiac devices. In doing so, we continue to shed light on the phenomenon first identified through Wenckebach’s meticulous attention to detail some 120 years ago.

Aims Unipolar voltage (UV) mapping is increasingly used for guiding ablative therapy of atrial fibrillation (AF) as unipolar electrograms (U-EGMs) are independent of electrode orientation and atrial wavefront direction. This study was aimed at constructing individual, high-resolution sinus rhythm (SR) UV fingerprints to identify low-voltage areas and study the effect of AF episodes in patients with mitral valve disease (MVD). Methods and results Intra-operative epicardial mapping (interelectrode distance 2 mm) of the right and left atrium, Bachmann’s bundle (BB), and pulmonary vein area was performed in 67 patients (27 male, 67 ± 11 years) with or without a history of paroxysmal AF (PAF). In all patients, there were considerable regional variations in voltages. UVs at BB were lower in patients with PAF compared with those without [no AF: 4.94 (3.56–5.98) mV, PAF: 3.30 (2.25–4.57) mV, P = 0.006]. A larger number of low-voltage potentials were recorded at BB in the PAF group [no AF: 2.13 (0.52–7.68) %, PAF: 12.86 (3.18–23.59) %, P = 0.001]. In addition, areas with low-voltage potentials were present in all patients, yet we did not find any predilection sites for low-voltage potentials to occur. Conclusion Even in SR, advanced atrial remodelling in MVD patients shows marked inter-individual and regional variation. Low UVs are even present during SR in patients without a history of AF indicating that low UVs should carefully be used as target sites for ablative therapy.

The usage of flavored electronic nicotine delivery systems (ENDS) is popular, specifically in the teen and young adult age-groups. The possible cardiac toxicity of the flavoring aspect of ENDS is largely unknown. Vaping, a form of electronic nicotine delivery, uses “e-liquid” to generate “e-vapor,” an aerosolized mixture of nicotine and/or flavors. We report our investigation into the cardiotoxic effects of flavored e-liquids. E-vapors containing flavoring aldehydes such as vanillin and cinnamaldehyde, as indicated by mass spectrometry, were more toxic in HL-1 cardiomyocytes than fruit-flavored e-vapor. Exposure of human induced pluripotent stem cell-derived cardiomyocytes to cinnamaldehyde or vanillin-flavored e-vapor affected the beating frequency and prolonged the field potential duration of these cells more than fruit-flavored e-vapor. In addition, vanillin aldehyde-flavored e-vapor reduced the human ether-à-go-go-related gene (hERG)-encoded potassium current in transfected human embryonic kidney cells. In mice, inhalation exposure to vanillin aldehyde-flavored e-vapor for 10 wk caused increased sympathetic predominance in heart rate variability measurements. In vivo inducible ventricular tachycardia was significantly longer, and in optical mapping, the magnitude of ventricular action potential duration alternans was significantly larger in the vanillin aldehyde-flavored e-vapor-exposed mice than in controls. We conclude that the widely popular flavored ENDS are not harm free, and they have a potential for cardiac harm. More studies are needed to further assess their cardiac safety profile and long-term health effects. NEW & NOTEWORTHY The use of electronic nicotine delivery systems (ENDS) is not harm free. It is not known whether ENDS negatively affect cardiac electrophysiological function. Our study in cell lines and in mice shows that ENDS can compromise cardiac electrophysiology, leading to action potential instability and inducible ventricular arrhythmias. Further investigations are necessary to assess the long-term cardiac safety profile of ENDS products in humans and to better understand how individual components of ENDS affect cardiac toxicity.