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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., (© 2018 Wiley Periodicals, Inc.)

Objectives: To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD)., Methods: We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted <6 weeks before enrolment or prior to 01/01/2000, with cPM/cICD-carriers undergoing chest x-ray, CT or follow-up (reference group, RG)., Results: 142 MRI (55 cardiac) were performed in 120 patients with cPM (n=71) or cICD (n=71). In the RG 98 measurements were performed in 95 patients with cPM (n=40) or cICD (n=58). No adverse events were observed. No MRI prolonged/interrupted. All cPM/cICD were correctly reprogrammed after MRI without malfunctions. One temporary communication failure was observed in one cPM-carrier. Immediately after MRI, 12/14 device interrogation parameters did not change significantly (clinically negligible changes of battery voltage and cICD charging time), without significant variations for SG versus RG. Three-12 months after MRI, 9/11 device interrogation parameters did not change significantly (clinically negligible changes of battery impedance/voltage). Non-significant changes of three markers of myocardial necrosis. Non-cardiac MRI: 82/87 diagnostic without artefacts; 4/87 diagnostic with artefacts; 1/87 partially diagnostic. Cardiac MRI: in cPM-carriers, 14/15 diagnostic with artefacts, 1/15 partially diagnostic; in cICD-carriers, 9/40 diagnostic with artefacts, 22 partially diagnostic, nine non-diagnostic., Conclusions: A favourable risk-benefit ratio of 1.5-T MRI in cPM/cICD carriers was reported., Key Points: • Cooperation between radiologists and cardiac electrophysiologists allowed safe 1.5-T MRI in cPM/cICD-carriers. • No adverse events for 142 MRI in 71 cPM-carriers and 71 cICD-carriers. • Ninety-nine per cent (86/87) of non-cardiac MRI in cPM/cICD-carriers were diagnostic. • All cPM-carrier cardiac MRIs had artefacts, 14 examinations diagnostic, 1 partially diagnostic. • Twenty-three per cent (9/40) of cardiac MRI in cICD-carriers were non-diagnostic.

Background and Objective: The early diagnosis of stomach cancer can be performed by using a proper screening procedure. Chromoendoscopy (CH) is an image-enhanced video endoscopy technique, which is used for inspection of the gastrointestinal-tract by spraying dyes to highlight the gastric mucosal structures. An endoscopy session can end up with generating a large number of video frames. Therefore, inspection of every individual endoscopic-frame is an exhaustive task for the medical experts. In contrast with manual inspection, the automated analysis of gastroenterology images using computer vision based techniques can provide assistance to endoscopist, by finding out abnormal frames from the whole endoscopic sequence., Methods: In this paper, we have presented a new feature extraction method named as Gabor-based gray-level co-occurrence matrix (G2LCM) for computer-aided detection of CH abnormal frames. It is a hybrid texture extraction approach which extracts a combination both local and global texture descriptors. Moreover, texture information of a CH image is represented by computing the gray level co-occurrence matrix of Gabor filters responses. Furthermore, the second-order statistics of these co-occurrence matrices are computed to represent images' texture., Results: The obtained results show the possibility to correctly classifying abnormal from normal frames, with sensitivity, specificity, accuracy, and area under the curve as 91%, 82%, 87% and 0.91 respectively, by using a support vector machine classifier and G2LCM texture features., Conclusion: It is apparent from results that the proposed system can be used for providing aid to the gastroenterologist in the screening of the gastric tract. Ultimately, the time taken by an endoscopic procedure will be sufficiently reduced., (Copyright © 2018 Elsevier B.V. All rights reserved.)

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., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Computer-aided analysis of clinical pathologies is a challenging task in the field of medical imaging. Specifically, the detection of abnormal regions in the frames collected during an endoscopic session is difficult. The variations in the conditions of image acquisition, such as field of view or illumination modification, make it more demanding. Therefore, the design of a computer-assisted diagnostic system for the recognition of gastric abnormalities requires features that are robust to scale, rotation, and illumination variations of the images. Therefore, this study focuses on designing a set of texture descriptors based on the Gabor wavelets that will cope with certain image dynamics. The proposed features are extracted from the images and utilized for the classification of the chromoendoscopy (CH) frames into normal and abnormal categories. Moreover, to attain a higher accuracy, an optimized subset of descriptors is selected through the genetic algorithm. The results obtained using the proposed features are compared with other existing texture descriptors (e.g., local binary pattern and homogeneous texture descriptors). Furthermore, the selected features are used to train the support vector machine (SVM), naive Bayes (NB) algorithm, k-nearest neighbor algorithm, linear discriminant analysis, and ensemble tree classifier. The performance of these state-of-the-art classifiers for different texture descriptors is compared based on the accuracy, sensitivity, specificity, and area under the curve (AUC) derived by using the CH images. The classification results reveal that the SVM classifier achieves 90.0% average accuracy and 0.93 AUC when it is employed with an optimized set of features obtained by using a genetic algorithm., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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., (© 2016 Wiley Periodicals, Inc.)

Aim: To describe the long-term follow-up of patients with complex congenital heart disease who underwent subcutaneous implantable cardiac defibrillator (S-ICD), focusing on local complications, appropriate and inappropriate shocks., Methods: Patients with complex congenital heart disease underwent S-ICD implant in two centers with the conventional technique. Data at follow-up were retrieved from clinical notes and institutional database., Results: Eight patients were implanted in two centres between 2010 and 2016. Median age at implant was 37.5 years (range 13-57). All patients who were deemed suitable for S-ICD implant passed the pre-procedural screening. Three patients were previously implanted with a anti-bradycardia device, one of whom with CRT. In one patient the device was explanted due to local infection. During the total median follow-up of 874 d, one patient had an appropriate and one inappropriate shock triggered by fast atrial tachycardia. None of the patients had inappropriate shocks secondary to T wave oversensing or electrical interference with anti- bradycardia devices., Conclusion: S-ICD appears to be effective and safe in patients with complex congenital heart disease., Competing Interests: Conflict-of-interest statement: No conflict of interest relative to this research.

The implantable cardioverter-defibrillator (ICD) has shown its superiority to anti-arrhythmic drugs in the prevention of sudden cardiac death. However, the conventional transvenous ICDs are still associated with substantial risks and comorbidities mainly related to the transvenous leads. The recent advent of an entirely sub-cutaneous ICD (S-ICD) represents an important progress in the defibrillation technology towards a less invasive approach. Clinical data are growing regarding the safety and efficacy of S-ICD in prevention of sudden cardiac death in selected patients without pacing indications. This novel technology seems promising and particularly beneficial in young patients with channelopathies, conditions at high risk of infection, or in those who experienced previous complications related to the transvenous leads. The S-ICD technology is still developing regarding the device, diagnostic capabilities, and the surgical implantation technique. Further advancements and potential integration with the leadless pacing technology may realize an outstanding evolution in defibrillation therapy and prevention of sudden cardiac death in the near future., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Complete left bundle branch block (LBBB) is established according to standard electrocardiographic criteria. However, functional LBBB may be rate-dependent or can perpetuate during tachycardia due to repetitive concealed retrograde penetration of impulses through the contralateral bundle "linking phenomenon." In this brief article, we present two patients with basal complete LBBB in whom ablating the right bundle unmasked the actual antegrade conduction capabilities of the left bundle. These cases highlight intriguing overlap between electrophysiological concepts of complete block, linking, extremely slow, and concealed conduction., (© 2016 Wiley Periodicals, Inc.)

Ventricular fibrillation is typically the initial arrhythmia in commotio cordis following precordium impacts that occur within an electrically vulnerable period of the cardiac cycle. Conversely, complete heart block is very rare in this context, and its mechanism and temporal course are poorly understood. The presented case concerns a 12-year-old boy, athletic skier, who developed a transient complete heart block following commotio cordis. The electrocardiographic features, the proposed block level and mechanisms of complete heart block following commotio cordis are discussed., (Copyright © 2016 Elsevier Inc. All rights reserved.)

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., (© 2016 Wiley Periodicals, Inc.)

Background: 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., Objective: 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)., Methods: 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., Results: 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., Conclusion: An NCP in both UEGM and BEGM may be an additional criterion that helps to localize the SOO of focal ventricular arrhythmias., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

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.

Although conventional implantable cardioverter-defibrillators (ICDs) have proved effective in the prevention of sudden cardiac death (SCD), they still appear to be limited by non-trivial acute and long-term complications. The recent advent of an entirely subcutaneous ICD (S-ICD) represents a further step in the evolution of defibrillation technology towards a less-invasive approach. This review highlights some historical and current issues concerning the S-ICD that may offer a viable therapeutic option in selected patients at high risk of SCD and in whom pacing is not required. After the CE Mark and US Food and Drug Administration (FDA) approvals, the S-ICD is being implanted worldwide with growing clinical data regarding its safety and efficacy (the EFFORTLESS Registry). The recently developed new generation of S-ICD (EMBLEM, Boston Scientific) demonstrates favourable features including a smaller device, longer longevity and remote-monitoring compatibility. Further innovations in the S-ICD system and potential integration with leadless pacing may play an important role in defibrillation therapy and prevention of SCD in the near future.

We report a case of a false asystole detected by an implantable loop recorder a few days after its implantation. In the discussion section we try to give some hints to help cardiac electrophysiologists in distinguish true from false asystoles, in order to avoid unuseful and potentially dangerous implantations of pacemakers., (© 2014 Wiley Periodicals, Inc.)

Transvenous implantable cardioverter-defibrillators (ICD) for the primary and secondary prevention of sudden cardiac death due to ventricular tachycardia/fibrillation have led to a significant improvement in survival in high-risk populations. Although conventional transvenous ICD therapy is currently widely used, it is associated with severe intra- and perioperative complications related to the use of transvenous leads, mostly occurring late after implantation. The recent introduction of a new ICD system with fully subcutaneous sensing and shocking capabilities has provided a valuable therapeutic option for special patient groups, allowing to identify and stop malignant ventricular arrhythmias while discriminating them from high-rate supraventricular tachyarrhythmias. This has also given us the opportunity to analyze the advantages and limitations of both implantable lifesaving electrical therapies. In the present paper, the technical characteristics of subcutaneous ICDs are described along with the recent advances in clinical and experimental research that have led to the introduction of these devices into clinical practice (over 1000 patients have been treated worldwide since 2009). Subcutaneous ICDs are indicated for both primary and secondary prevention of cardiac arrest in patients at risk for acquired or congenital arrhythmogenic diseases, including those with an underlying genetic molecular mechanism, provided that they do not require antibradycardia or antitachycardia pacing or cardiac resynchronization therapy, which represent the main limitations of these new devices. A subcutaneous ICD system has the advantage of avoiding the need for transvenous leads, making its implantation or removal much simpler without requiring fluoroscopic guidance. In addition, subcutaneous ICDs can be used in children, young subjects and athletes, and in all patients for whom venous access may be difficult to achieve.

The recent advent of an entirely subcutaneous implantable defibrillator (ICD) has provided a relevant contribution to the debate concerning the use of ICD therapy in patients at high risk for death. Although conventional transvenous ICDs have proven very effective during the past 23 years, they still appear to be limited by nontrivial acute and long-term complications. This study delineates some of the historical and current issues characterizing the advent of the subcutaneous ICD system in daily clinical practice. Subcutaneous ICDs have proven effective in more than 1100 patients worldwide and appear to be competitive with transvenous ICD in all clinical conditions not requiring antibradycardia, antitachycardia, or cardiac resynchronization pacing., (Copyright © 2012 Elsevier Inc. All rights reserved.)

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.

A 25-year-old woman with drug-refractory permanent junctional reciprocating tachycardia (PJRT) and a previous failed ablation, was referred to our institution. Electrophysiological study confirmed the diagnosis of orthodromic atrioventricular reentry tachycardia using a slowly conducting accessory pathway. This accessory pathway was successfully ablated by conventional radiofrequency at the left anteroseptal region using a transseptal approach. Catheter ablation of this accessory pathway (Coumel type) at the mitral annulus-aorta junction offers insights on a rare anatomical location of PJRT.