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This study aimed to collect and analyze the literature data regarding Chiari network (CN) and other right atrium (RA) remnants comprising the Eustachian and Thebesian valves (EV, ThV) as a potential entrapment site during different percutaneous cardiac procedures (PCP).A systematic search was conducted using Pubmed and Embase databases following the PRISMA guidelines to obtain available data concerning PCP associated with entrapment of inserted materials within CN-EV-ThV. The final analysis included 41 patients who underwent PCP with reported material entrapment within these RA remnants. The PCP was atrial septal defect (ASD)/patent foramen ovale (PFO) closure, catheter ablation, and pacemaker/defibrillator implantation in 44%, 22%, and 17% of patients, respectively. The entrapped materials were ASD/PFO devices, multipolar electrophysiology catheters, passive-fixation pacing leads, and J-guidewires in about 30%, 20%, 15%, and 10% of patients, respectively. Intraprocedural transthoracic, transoesophageal and intracardiac echocardiography showed sensitivity to reveal these structures of 20%, ∼95%, and 100%, respectively. A percutaneous approach successfully managed 70% of patients, while cardiovascular surgery was required in 20% and three patients died (7.3%).CN and other RA remnants may cause entrapment of various devices or catheters during PCP requiring right heart access. The percutaneous approach, guided by intraprocedural imaging, appears safe and effective in managing most patients. Prevention includes recognizing these anatomical structures at baseline cardiac imaging and intraprocedural precautions. Further studies are needed to analyze the actual incidence of this condition, its clinical impact and appropriate management.

To evaluate the clinical outcomes of oral mexiletine (oMXT) to treat ventricular tachyarrhythmias (VTAs) in the era of implantable cardioverter-defibrillator (ICD) technology.A systematic search was conducted using Pubmed, Embase and Cochrane databases following the PRISMA guidelines to collect literature data reporting oMXT efficacy and safety outcomes in treating VTAs in ICD recipients.Final analysis included four studies accounting for a total of 91 patients with recurrent VTAs treated with oMXT. Amiodarone therapy was initially attempted in most patients (91.2%), while catheter ablation was performed in one-third of patients. VTA recurrences were observed in 55/91 patients (60.4%) during oMXT treatment compared to 91/91 (100%) before treatment (p0.001). Appropriate therapies occurred in 55/88 ICD patients (62.5%) during oMXT treatment compared to 80/88 (90.9%) before treatment (p0.001). After oMXT introduction, there was a significant reduction of the individual burden of VTA episodes and appropriate ICD therapies per patient, showing Hedges'g values of -1.103 (p = 0.002) and -1.474 (p = 0.008), respectively. Safety analysis showed a sample-weighted overall side-effect rate of 30%, while 21% of patients required drug reduction or discontinuation. Aggregated meta-regression analysis of the included studies and remote literature revealed a linear correlation between oMXT dosage and the overall side effects rate (r2 = 0.48; p = 0.014).Oral mexiletine provides an adjunctive treatment to manage VTAs and reduces appropriate therapies in ICD patients with moderate efficacy and acceptable safety profiles. These observations await confirmation through randomised clinical trials.

Aims Air entrapment (AE) has been reported as a potential cause of early inappropriate shocks (ISs) following subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, but a cause–effect relationship is not always evident. This systematic review aims to analyse this phenomenon concerning implantation techniques, electrogram (EGM) features, radiologic findings, and patient management. Methods and results A systematic search was conducted using PubMed, Embase, and Google Scholar databases following the PRISMA guidelines to obtain all available literature data since 2010 on S-ICD malfunctions possibly due to AE. The final analysis included 54 patients with AE as a potential cause of S-ICD malfunction. Overall, the aggregate incidence of this condition was 1.2%. Of ICD malfunctions possibly due to AE, 93% were ISs, and 95% were recorded within the first week following implantation. Radiologic diagnosis of AE was confirmed in 28% of the entire study cohort and in 68% of patients in whom this diagnostic examination was reported. At the time of device malfunction, EGMs showed artefacts, baseline drift, and QRS voltage reduction in 95, 76, and 67% of episodes, respectively. Management included ICD reprogramming or testing, no action (observation), and invasive implant revision in 57, 33, and 10% of patients, respectively. No recurrences occurred during follow-up, irrespective of management performed. Conclusions Device malfunction possibly due to AE may occur in ∼1% of S-ICD recipients. Diagnosis is strongly suggested by early occurrence, characteristic EGM features, and radiologic findings. Non-invasive management, principally device reprogramming, appears to be effective in most patients.

In patients with cancer, the safety of catheter ablation for non-valvular atrial fibrillation (AF) has not been evaluated, yet. The aim of this study was to assess the safety of AF ablation in cancer survivors. Consecutively recruited patients undergoing catheter ablation of non-valvular AF at our center between March 2015 and March 2017 were evaluated. The primary outcome of the study was clinically relevant bleedings occurred within 30 ± 5 days after the procedure. Patients with cancer were propensity matched to patients without cancer in a 1:3 and 1:6 ratio after stratification by baseline clinical features. Overall, 184 patients were included in the study. Of them, 21 (11%) were cancer survivors. Cancer site was more frequently gastrointestinal (36%), breast (23%), and genitourinary (18%). At 30 ± 5 days, clinically relevant bleedings occurred in 14 patients. Crude odds ratio (OR) for clinically relevant bleedings was 3.60 (95% CI 1.02–12.7) higher in cancer than in non-cancer patients. This trend remained after propensity score–matched population (OR 3.48, 95% CI 0.76–15.90 for matched 1:3, OR 4.95, 95% CI 1.2–20.2 for matched 1:6). Type of anticoagulation was not associated with bleedings. Preliminary results suggest that clinically relevant bleeding after catheter ablation for AF is more frequent in cancer survivors than in patients without cancer. Further studies are required to confirm the present data.

More than 2 decades ago, para-Hisian pacing was introduced to assess the pattern of retrograde conduction during electrophysiological studies. Although there is no ideal maneuver for every patient and condition, para-Hisian pacing is a valuable and handy strategy to differentiate between retrograde conduction over the atrioventricular node and the accessory pathways. The dynamic behavior of para-Hisian pacing, in a region with unique anatomical features, can produce various activation patterns and intriguing electrophysiological phenomena. Although the demonstration of a retrograde nodal activation pattern during para-Hisian pacing does not rule out the presence of an accessory pathway, evidence of retrograde conduction over an accessory pathway does not prove its active role in the culprit tachycardia. Multipolar His bundle recordings, detailed atrial mapping, and recognition of the truly captured structures and the impact of temporal changes of autonomic tone or pacing rates, are essential keys for accurate interpretation of this maneuver that may ultimately guide judicious catheter ablation of the arrhythmic substrate. This review aims to summarize the practical usefulness and potential pitfalls of the para-Hisian pacing maneuver, focusing on the interpretation of electrocardiograms and intracardiac recordings.

This case concerns a 24‐year‐old female who developed malignant ventricular tachyarrhythmia a few weeks after pacemaker implantation for complete heart block. Apparently, right ventricular pacing caused significant repolarization abnormalities in both native and paced rhythms with marked QT prolongation and substantial electrical instability. This case highlights other intriguing phenomena in the puzzle of cardiac repolarization and how pacing therapy may alter this complex process providing arrhythmic substrate in vulnerable subjects. Though such arrhythmic events are clinically rare, vulnerable patients or with suspected myocardial disease that may cause QT prolongation should be carefully followed in the course of pacing therapy.

To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD). We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted

The underlying mechanisms and temporal course of complete heart block (CHB) after blunt cardiac injuries (BCIs) are poorly understood, and a systematic analysis of available data is lacking. In this systematic review, PubMed was searched for publications of reported cases of CHB-BCI analyzing clinical findings, electrocardiographic features, temporal course, and outcomes. Case reports on CHB-BCI were available for 50 patients, mainly secondary to traffic or sport accidents. A fatal outcome occurred in 10 of 50 (20%) of patients, while a structural damage of the atrioventricular (AV) conductive system was evident in 4 of 8 (50%) of necropsy studies. Clinical manifestation of CHB-BCI occurred within 72 hours of injury in 38 of 47 (∼80%) of patients, and 1:1 AV conduction was restored within 7–10 days in about half of early survivors. Permanent pacemaker implantation was indicated in 22 of 42 (∼50%) of early survivors because of recurrent or permanent CHB. Cardiac troponins, when analyzed, were elevated in 12 of 13 (∼90%) of patients, and electrocardiographic features of aberrancy were present in 29 of 40 (>70%) of patients. In conclusion, CHB secondary to BCI is associated with 20% mortality mainly occurring in the early posttraumatic period and most of the deaths are due to or triggered by this malignant arrhythmia. Recurrent or permanent CHB requiring pacemaker implantation occurs in ∼50% of survivors. A structural damage of the AV conductive system can be found in 50% of necropsy studies.

More than 2 decades ago, para-Hisian pacing was introduced to assess the pattern of retrograde conduction during electrophysiological studies. Although there is no ideal maneuver for every patient and condition, para-Hisian pacing is a valuable and handy strategy to differentiate between retrograde conduction over the atrioventricular node and the accessory pathways. The dynamic behavior of para-Hisian pacing, in a region with unique anatomical features, can produce various activation patterns and intriguing electrophysiological phenomena. Although the demonstration of a retrograde nodal activation pattern during para-Hisian pacing does not rule out the presence of an accessory pathway, evidence of retrograde conduction over an accessory pathway does not prove its active role in the culprit tachycardia. Multipolar His bundle recordings, detailed atrial mapping, and recognition of the truly captured structures and the impact of temporal changes of autonomic tone or pacing rates, are essential keys for accurate interpretation of this maneuver that may ultimately guide judicious catheter ablation of the arrhythmic substrate. This review aims to summarize the practical usefulness and potential pitfalls of the para-Hisian pacing maneuver, focusing on the interpretation of electrocardiograms and intracardiac recordings.

Aim Ectopic atrial tachycardia (EAT) is a common arrhythmia in children, adolescents, and young adults. Radiofrequency (RF) ablation is often considered the treatment of choice in this population. We sought to evaluate the long‐term follow‐up after RF ablation. Methods and Results We retrospectively analyzed 36 young patients (age range 8‐29 years), with clinical signs and symptoms suspected for EAT who underwent an electrophysiological study in our center. We evaluated the safety and acute success rate of ablation and the long‐term follow‐up. Ectopic foci were more frequently localized in the right atrium along the crista terminalis (28%) and EAT was successfully terminated in 97% of patients. At median follow‐up (38 months), the recurrence rate was 20% with mostly recurrences expressed within 6 months. Conclusions The study confirmed the safety and high acute success rate of EAT ablation in a population of children, adolescents, and young adults. Therefore, catheter ablation of EAT can be considered early in the course of treatment of these patients. The evidence of most recurrences within 6 months could be useful for advising patients on likely outcomes.

Junctional and AV nodal reentrant tachycardia share common electrocardiographic features, but they differ in their management and outcomes after catheter ablation. This case concerns a 60-year-old female who presented with recurrent episodes of a relatively slow, regular supraventricular arrhythmia. Electrocardiographic features of the arrhythmia were discordant regarding its underlying mechanism. However, careful analysis of 12-lead electrocardiograms, with focus on the effect of spontaneous premature beats, pointed out the arrhythmia etiology. Electrophysiological study and pacing maneuvers defined the arrhythmic substrate that was successfully treated by catheter ablation.

The subcutaneous implantable cardioverter defibrillator (S-ICD) is a valuable alternative to the conventional trans-venous ICD (TV-ICD) for the prevention of sudden cardiac death (SCD). Prospective registries showed that the S-ICD is safe and effective in treating ventricular tachyarrhythmias in high-risk patients without pacing indications. While in earlier studies patients implanted with S-ICDs were young and mostly affected by channelopathies, contemporary S-ICD cohorts include patients with severely impaired left ventricular function and significant comorbidities. This review focuses on S-ICD evidence-based use and highlights current gaps between guidelines recommendations and real-world clinical practice.

Intravenous adenosine is a short-acting blocker of the atrioventricular node that has been used to unmask subtle or latent preexcitation, and also to enable catheter ablation in selected patients with absent or intermittent preexcitation. Depending on the accessory pathway characteristics, intravenous adenosine may produce specific electrocardiographic changes highly suggestive of the preexcitation variant. Herein, we view different ECG responses to this pharmacological test in various preexcitation patterns that were confirmed by electrophysiological studies. Careful analysis of electrocardiographic changes during adenosine test, with emphasis on P-delta interval, preexcitation degree, and atrioventricular block, can be helpful to diagnose the preexcitation variant/pattern.

The relevance of the temporal relationship between a unipolar electrogram (UEGM) and a bipolar electrogram (BEGM) in determining the site of origin (SOO) of focal arrhythmias has been largely demonstrated.We sought to demonstrate that a negative concordance in the initial forces of these EGMs is also helpful in predicting the SOO of premature ventricular contractions (PVCs).Mapping and radiofrequency (RF) ablation were performed in 41 patients with symptomatic PVCs in the absence of structural heart disease. Simultaneous recordings of the minimally filtered (0.5-500 Hz) UEGM and filtered BEGM (30-500 Hz) were analyzed at 247 mapping sites, where RF was attempted. EGMs of 63 mechanically induced PVCs were separately analyzed as a validation group. All ablation sites had a QS pattern in the UEGM. Acute PVC suppression was defined as a complete disappearance of ventricular ectopic beats after a 60-second pulse of RF.RF ablation obtained PVC suppression (RF+) in 33 of 247 sites (13.3%). A negative concordance pattern (NCP) during the initial 20 ms of both UEGM and BEGM was observed in 31 of 33 (94%) RF+ sites compared with 10 of 214 (4%)RF- sites (P.0001). The NCP criterion demonstrated to be an additional powerful predictor of acute RF success with sensitivity, specificity, positive predictive value, and negative predictive value of 94%, 95%, 76%, and 99%, respectively. Similarly to RF+ sites, the NCP was observed in 60 of 63 sites (95.2%) in the mechanical PVC group.An NCP in both UEGM and BEGM may be an additional criterion that helps to localize the SOO of focal ventricular arrhythmias.

Introduction Fasciculoventricular and nodoventricular pathways (FVP and NVP) are uncommon preexcitation variants that can be misleading during electrophysiology studies (EPSs), and differentiating them could be challenging. In this article, we describe 2 representative cases and then we present various electrophysiological features and phenomenon encountered in patients with these particular accessory pathways (APs).

Regular narrow QRS tachycardia, particularly if well‐tolerated, is usually considered a “benign” arrhythmia of a supraventricular origin. This case concerns an 82‐year‐old male with ischemic heart disease who presented with recurrent episodes of a narrow QRS tachycardia that was initially diagnosed and treated as atrial tachyarrhythmia. However, careful physical examination and ECG analysis established the correct diagnosis, and the patient was managed appropriately. Remarkably, the observation of irregular cannon A waves, and Lewis lead recording, confirmed atrioventricular dissociation during tachycardia and indicated its underlying mechanism.

Background— QRS-ST changes in the inferior and lateral ECG leads are frequently observed in athletes. Recent studies have suggested a potential arrhythmogenic significance of these findings in the general population. The aim of our study was to investigate whether QRS-ST changes are markers of cardiac arrest (CA) of unexplained cause or sudden death in athletes. Methods and Results— In 21 athletes (mean age, 27 years; 5 women) with cardiac arrest or sudden death, the ECG recorded before or immediately after the clinical event was compared with the ECG of 365 healthy athletes eligible for competitive sport activity. We measured the height of the J wave and ST elevation and searched for the presence of QRS slurring in the terminal portion of QRS. QRS slurring in any lead was present in 28.6% of cases and in 7.6% of control athletes ( P =0.006). A J wave and/or QRS slurring without ST elevation in the inferior (II, III, and aVF) and lateral leads (V 4 to V 6 ) were more frequently recorded in cases than in control athletes (28.6% versus 7.9%, P =0.007). Among those with cardiac arrest, arrhythmia recurrences did not differ between the subgroups with and without J wave or QRS slurring during a median 36-month follow-up of sport discontinuation. Conclusions— J wave and/or QRS slurring was found more frequently among athletes with cardiac arrest/sudden death than in control athletes. Nevertheless, the presence of this ECG pattern appears not to confer a higher risk for recurrent malignant ventricular arrhythmias.

Introduction: Atrial fibrillation (AF) may occasionally affect athletes by impairing their ability to compete, and leading to noneligibility at prequalification screening. The impact of catheter ablation (CA) in restoring full competitive activity of athletes affected by AF is not known. The aim of our study was to investigate the effectiveness of CA of idiopathic AF in athletes with palpitations impairing physical performance and compromising eligibility for competitive activities. Methods and Results: Twenty consecutive competitive athletes (all males; 44.4 ± 13.0 years) with disabling palpitations on the basis of idiopathic drug-refractory AF underwent 46 procedures (2.3 ± 0.4 per patient) according to a prospectively designed multiprocedural CA approach that consolidates pulmonary veins (PV) isolation through subsequent steps. Preablation, effort-induced AF could be documented in 13 patients (65%) during stress ECG and significantly reduced maximal effort capacity (176 ± 21 W), as compared with patients with no AF during effort (207 ± 43 W, P < 0.05). At the end of CA protocol, which also included ablation of atrial flutter (AFL) in 7 patients, 18 (90.0%) patients were free of AF and two (10.0%) reported short-lasting (minutes) episodes of palpitations during 36.1 ± 12.7 months follow-up. Compared with preablation, postablation maximal exercise capacity significantly improved (from 183 ± 32 to 218 ± 20 W, P < 0.02). All baseline quality of life (QoL) parameters pertinent to physical activity significantly improved (P < 0.05) at the end of CA protocol. All athletes obtained reeligibility and could effectively reinitiate sport activity. Conclusions: AF, alone or in combination with AFL, may significantly impair maximal effort capacity thereby limiting competitive performance. Multiple PV isolation proved very effective in these patients to restore full competitive activity and allow reeligibility.

Left ventricular hypertrophy (LVH) is accompanied by specific changes of the cellular electrophysiology, which are potentially arrhythmogenic, mainly prolongation of action potential duration due to down-regulation of several K channels. Moreover, transmural dispersion of repolarization due to presence of cell types with different repolarization properties within the ventricular wall plays an essential role in the development of transmural functional reentry responsible for the maintenance of ventricular tachycardia (VT), once it has been initiated. Experimental evidence has been provided that phase 2 early afterdepolarizations (EAD) can be generated from hypertrophied left ventricular wall in the absence of action potential duration (APD) prolonging agents. Phase 2 EADs could be associated with malignant "R on T" extrasystoles, initiating polymorphic VT. Unfortunately, the abnormalities of ventricular repolarization are not always revealed on surface electrocardiogram (ECG) and when present they have a low predictive power for occurrence of life-threatening arrhythmias and sudden cardiac death. In order to reveal signs of repolarization heterogeneities not apparent from 12-lead ECG analysis, we studied body surface potential maps in a group of patients with LVH due to valvular aortic stenosis. The similarity index was significantly lower and the late repolarization deviation index was significantly higher in patients than in normal subjects. These findings suggested a higher than normal degree of heterogeneities of repolarization in LVH patients, not detected by the usual ECG analysis.

A 24-year-old female underwent an electrophysiological study because of recurrent episodes of drug-refractory, paroxysmal supraventricular tachycardia. During adrenergic stress, a narrow QRS tachycardia with eccentric atrial activation was reproducibly inducible. The response to premature ventricular extrastimulation during tachycardia suggested the presence of a slowly conducting accessory pathway. However, a comprehensive appraisal of the electrophysiological study delineated the tachycardia substrate as an atypical atrioventricular nodal reentrant tachycardia in the presence of a bystander nodofascicular pathway. Careful analysing of the basal pacing manoeuvers during sinus rhythm (para-Hisian and differential ventricular pacing) was crucial to establish the correct diagnosis and to avoid unnecessary left-side access to ablate this tachycardia.

A 78-year-old woman with unstable angina underwent coronary bypass surgery with complete cardiac revascularization and no immediate postoperative complications. Six days after surgery, during hospitalization for cardiac rehabilitation, the patient developed severe respiratory distress and pulmonary embolism was diagnosed. Color duplex ultrasound revealed the presence of concomitant upper extremity deep vein thrombosis (UEDVT), ipsilateral to the site of placement of a central venous line, in the absence of lower extremity deep vein thrombosis. We describe this case and provide preliminary data from a prospective observational study evaluating the prevalence of catheter-related UEDVT and symptomatic pulmonary embolism (55 and 1.4% respectively) in a series of 71 consecutive coronary bypass surgery patients admitted to a cardiac rehabilitation facility. Catheter-related UEDVT and pulmonary embolism may complicate coronary bypass surgery and should be taken into consideration when managing patients after surgery.

Cardiac involvement in myotonic dystrophy type 1 (DM1) is frequent with increased incidence of conduction disturbances and sudden cardiac death when compared with general population. We describe a 38-year-old man in whom the diagnosis of DM1 was made 8 years after occurrence of cardiac arrest owing to ventricular fibrillation and discuss management of DM1 patients at risk for sudden cardiac death.

A 15-year-old female with WPW syndrome and normal heart underwent an electrophysiology study for paroxysmal palpitations and syncope. Intravenous adenosine produced an unexpected response of QRS changes and advanced AV block. During isoproteronol infusion, short-lasting and poorly tolerated wide QRS tachycardia was inducible, but pacing maneuvers were not feasible during tachycardia to determine its definitive mechanism. However, various electrophysiologic phenomena including adenosine response, junctional beats pattern, and multisite atrial pacing were helpful to overcome the diagnosis challenges. Finally, careful evaluation of tachycardia features and the comprehensive electrophysiology study were crucial to establish presence of unusual preexcitation variants, and thus to guide successful catheter ablation of the arrhythmic substrate.