LDCNN: A new arrhythmia detection technique with ECG signals using a linear deep convolutional neural network.

The electrocardiogram (ECG) is a fundamental and widely used tool for diagnosing cardiovascular diseases. It involves recording cardiac electrical signals using electrodes, which illustrate the functioning of cardiac muscles during contraction and relaxation phases. ECG is instrumental in identifying abnormal cardiac activity, heart attacks, and various cardiac conditions. Arrhythmia detection, a critical aspect of ECG analysis, entails accurately classifying heartbeats. However, ECG signal analysis demands a high level of expertise, introducing the possibility of human errors in interpretation. Hence, there is a clear need for robust automated detection techniques. Recently, numerous methods have emerged for arrhythmia detection from ECG signals. In our research, we developed a novel one-dimensional deep neural network technique called linear deep convolutional neural network (LDCNN) to identify arrhythmias from ECG signals. We compare our suggested method with several state-of-the-art algorithms for arrhythmia detection. We evaluate our methodology using benchmark datasets, including the PTB Diagnostic ECG and MIT-BIH Arrhythmia databases. Our proposed method achieves high accuracy rates of 99.24% on the PTB Diagnostic ECG dataset and 99.38% on the MIT-BIH Arrhythmia dataset.

Stretch of the papillary insertion triggers reentrant arrhythmia: an in silico patient study.

Background: The electrophysiological mechanism connecting mitral valve prolapse (MVP), premature ventricular complexes and life-threatening ventricular arrhythmia is unknown. A common hypothesis is that stretch activated channels (SACs) play a significant role. SACs can trigger depolarizations or shorten repolarization times in response to myocardial stretch. Through these mechanisms, pathological traction of the papillary muscle (PM), as has been observed in patients with MVP, may induce irregular electrical activity and result in reentrant arrhythmia. Methods: Based on a patient with MVP and mitral annulus disjunction, we modeled the effect of excessive PM traction in a detailed medical image-derived ventricular model by activating SACs in the PM insertion region. By systematically varying the onset of SAC activation following sinus pacing, we identified vulnerability windows for reentry with 1 ms resolution. We explored how reentry was affected by the SAC reversal potential ( E SAC ) and the size of the region with simulated stretch (SAC region). Finally, the effect of global or focal fibrosis, modeled as reduction in tissue conductivity or mesh splitting (fibrotic microstructure), was investigated. Results: In models with healthy tissue or fibrosis modeled solely as CV slowing, we observed two vulnerable periods of reentry: For E SAC of -10 and -30 mV, SAC activated during the T-wave could cause depolarization of the SAC region which lead to reentry. For E SAC of -40 and -70 mV, SAC activated during the QRS complex could result in early repolarization of the SAC region and subsequent reentry. In models with fibrotic microstructure in the SAC region, we observed micro-reentries and a larger variability in which times of SAC activation triggered reentry. In these models, 86% of reentries were triggered during the QRS complex or T-wave. We only observed reentry for sufficiently large SAC regions ( > = 8 mm radius in models with healthy tissue). Conclusion: Stretch of the PM insertion region following sinus activation may initiate ventricular reentry in patients with MVP, with or without fibrosis. Depending on the SAC reversal potential and timing of stretch, reentry may be triggered by ectopy due to SAC-induced depolarizations or by early repolarization within the SAC region.

Shensong yangxin, a multi-functional traditional Chinese medicine for arrhythmia: A review of components, pharmacological mechanisms, and clinical applications.

As a common cardiovascular disease (CVD), Arrhythmia refers to any abnormality in the origin, frequency, rhythm, conduction velocity, timing, pathway, sequence, or other aspect of cardiac impulses, and it is one of the common cardiovascular diseases in clinical practice. At present, various ion channel blockers are used for treatment of arrhythmia that include Na+ ion channel blockers, K+ ion channel blockers and Ca2+ ion channel blockers. While these drugs offer benefits, they have led to a gradual increase in drug-related adverse reactions across various systems. As a result, the quest for safe and effective antiarrhythmic drugs is pressing. Recent years have seen some advancements in the treatment of ventricular arrhythmias using traditional Chinese medicine(TCM). The theory of Luobing in TCM has proposed a new drug intervention strategy of "fast and slow treatment, integrated regulation" leading to a shift in mindset from "antiarrhythmic" to "rhythm-regulating". Guided by this theory, the development of Shen Song Yang Xin Capsules (SSYX) has involved various Chinese medicinal ingredients that comprehensively regulate the myocardial electrophysiological mechanism, exerting antiarrhythmic effects on multiple ion channels and non-ion channels. Similarly, in clinical studies, evidence-based research has confirmed that SSYX combined with conventional antiarrhythmic drugs can more effectively reduce the occurrence of arrhythmias. Therefore, this article provides a comprehensive review of the composition and mechanisms of action, pharmacological components, network pharmacology analysis, and clinical applications of SSYX guided by the theory of Luobing, aiming to offer valuable insights for improved clinical management of arrhythmias and related research.

Flecainide Toxicity From Clinical Pharmacology Perspectives.

We report a case comparing the measured half-life of flecainide with the half-life stated on the label. An 84-year-old woman presented with symptoms of anorexia and exertional dyspnea. She had undergone mitral and aortic valve replacements and excision of the membranous septum in the atrium for mitral and aortic stenosis and cor triatriatum. She was regularly administered 100 mg/day flecainide for paroxysmal atrial fibrillation. A previous electrocardiogram (ECG) showed a regular sinus rhythm. However, upon admission, the ECG revealed a heart rate of 94 bpm and an accelerated idioventricular rhythm originating from the left ventricle. Flecainide toxicity was suspected, leading to the discontinuation of flecainide treatment. The following day, the serum flecainide concentration was 1,348 ng/mL, exceeding the therapeutic window of 200-1,000 ng/mL. After discontinuing flecainide, the accelerated idioventricular rhythm ceased, and a regular sinus rhythm temporarily returned. We measured blood drug concentrations several times; our calculated half-life was 56.8 h, approximately five times longer than the half-life of 11.0 h stated on the package insert. To ensure safe and effective therapy with antiarrhythmic drugs, prioritizing therapeutic drug monitoring and carefully monitoring pharmacokinetics is important, particularly during the elimination phase.

Long QT Syndrome With Drugs Used in the Management of Arrhythmias: A Systematic Review.

Long QT syndrome (LQTS) is a severe cardiac disorder characterized by an abnormally prolonged QTc interval on an electrocardiogram (ECG), which can result in life-threatening irregular heart rhythms. The use of certain medications, particularly anti-arrhythmic drugs such as quinidine, sotalol, and amiodarone, can lead to acquired LQTS by prolonging the QT interval through the inhibition of specific ion channels responsible for heart repolarization, which may present symptoms like fainting, seizures, and sudden cardiac arrest. This systematic review, conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, focused on analyzing the association between Long QT syndrome and drugs utilized for managing arrhythmias, involving a thorough examination of six selected studies from an initial pool of 68 articles. It was found that antiarrhythmic drugs such as amiodarone, sotalol, dofetilide, procainamide, quinidine, and flecainide have the potential to cause QT prolongation as a side effect, which is often influenced by factors including dosage, coexisting medical conditions, electrolyte imbalances, and other risk factors. Prolonged QT interval significantly elevates the risk of a life-threatening arrhythmia called torsade de pointes. The management of this side effect typically involves reducing the medication dosage or discontinuing it altogether and, in some cases, employing selective beta blockers. However, further research is essential to improve the understanding and implementation of strategies to prevent and manage QT prolongation caused by antiarrhythmic drugs. Additional clinical studies are warranted to enhance knowledge and provide comprehensive guidelines to healthcare practitioners regarding the appropriate use of these medications. Close monitoring of the QT interval is recommended for patients receiving anti-arrhythmic therapy, and consideration should be given to patient-specific risk factors for LQTS, including age, sex, and electrolyte imbalances.

Review on spiking neural network-based ECG classification methods for low-power environments.

This paper reviews arrhythmia classification studies using electrocardiogram (ECG) signals. Research on automatically diagnosing arrhythmia in daily life has been actively underway for early detection and treatment of heart disease. Development of automatic arrhythmia classification using ECG signal began based on handcrafted morphological feature extraction and machine learning-based classification methods. As deep neural networks (DNN) show excellent performance in the signal processing field, studies using various types of DNN are also being conducted in ECG classification. However, these DNN-based studies have extremely high computational complexity, making it challenging to perform real-time classification, and are unsuitable for low-power environments such as wearable devices due to high power consumption. Currently, research based on spiking neural network (SNN), which mimics the low-power operation of the human nervous system, is attracting attention as a method that can dramatically reduce complexity and power consumption. The classification accuracy of the SNN-based ECG classification studies is close to that of the DNN-based studies. When combined with neuromorphic hardware, it shows ultra-low-power performance, suggesting the possibility of use in lightweight devices. In this paper, the SNN-based ECG classification studies for low-power environments are mainly reviewed, and prior to this, conventional and DNN-based ECG classification studies are also reviewed. We hope that this review will be helpful to researchers and engineers interested in the field of ECG classification.

Cardiovascular disease in connective tissue disease-associated interstitial lung disease: A systematic review and meta-analysis of observational studies.

OBJECTIVES: We performed a systematic review and meta-analysis to assess whether patients with connective tissue disease (CTD)-associated interstitial lung diseases (ILD) have an increased prevalence of cardiovascular (CV) disease and to validate associated risk factors. METHODS: The PRISMA guidelines and PICO model were followed. We searched PubMed, Embase, Cochrane Library databases, Scopus, and Directory of Open Access Journals from inception to April 2024. RESULTS: Thirteen studies comprising of 12,520 patients were included. Patients with CTD-ILD had a significantly increased risk of CV disease than patients with CTD (relative risk [RR] = 1.65, 95 % confidence interval [CI]: 1.41, 1.93), which are related to the proportion of men (P = 0.001) and the proportion of smokers (P = 0.045). Subgroup analysis found that patients with CTD-ILD had a higher risk of heart failure (RR = 2.84, 95 % CI: 1.50, 5.39), arrhythmia (RR = 1.55, 95 % CI: 1.22, 1.97) than patients with CTD. Another subgroup analysis showed that RA-ILD and SSc-ILD were associated with an increased risk of CV disease, but not IIM-ILD and MCTD-ILD (RA-ILD: RR = 2.19, 95 % CI: 1.27, 3.80; SSc-ILD: RR = 1.53, 95 % CI: 1.29, 1.82). Besides, patients with CTD-ILD had a higher prevalence of pulmonary arterial hypertension (RR = 2.48, 95 % CI: 1.69, 3.63) than patients with CTD. CONCLUSIONS: Patients with CTD-ILD had a 1.65 times increased risk of CV than patients with CTD-non-ILD, with increased prevalence of heart failure and arrhythmia. The risk of CV disease in SSc-ILD and RA-ILD is increased and we should pay more attention to male smokers. In addition, compared with CTD patients, CTD-ILD patients had a higher risk of pulmonary arterial hypertension.

Ventricular cardiac hemangiosarcoma with brain metastases in a dog.

An 11-year-old, female, spayed, soft-coated Wheaten terrier presented for acute onset of neurological signs. On presentation, neurological examination showed right thoracic and pelvic limb proprioceptive deficits, absent right menace reflex, and weak right nasal septum response. A left thalamocortical lesion was localized. On thoracic auscultation, an arrhythmia was noted, and electrocardiography showed frequent ventricular premature complexes and rare runs of ventricular tachycardia. Echocardiography identified an interventricular septal mass extending into the lumen of the left ventricle. Thalamocortical metastasis secondary to the cardiac mass was suspected to be the cause of the patient's neurological signs. Humane euthanasia was elected by the owner due to the patients clinical status and poor prognosis. A postmortem examination diagnosed hemangiosarcoma of the interventricular septum, the right ventricular free wall, and left ventricular free wall. The left ventricle adjacent to the paraconal groove showed myocardial necrosis and inflammation. Metastases to the brain and secondary intracranial hemorrhage were found which were suspected to be the cause of the antemortem neurological signs. Concurrent pulmonary and hepatic metastases were noted. This report describes a rare presentation of an intracardiac hemangiosarcoma of the interventricular septum, right ventricle, and left ventricle in a patient presenting with neurological signs.

[Epicardial ablation of ventricular tachycardia with cardiac surgery only : Pro/Contra]. / Epikardiale Ablation ventrikulärer Tachykardien nur mit Herzchirurgie : Pro/Contra.

During the ablation of ventricular arrhythmias (VA) complications can occur, albeit rather rarely, and their occurrence depends on various factors. On the one hand the patient's condition and comorbidities play a role, on the other hand the access site and the procedure itself can lead to complications which have to be addressed adequately. This article will discuss whether complex ablations with epicardial access should only be performed at centres with the appropriate expertise and a cardiac surgery department.

ß-Adrenergic receptor signalling pathway mediated antiarrhythmic activity of s-limonene in the rat heart.

S-Limonene (s-Lim) is a monocyclic monoterpene found in a variety of plants and has been shown to present antioxidant and cardioprotective activity in experimental models of myocardial infarction. The aim of this study was to evaluate the potential mechanism by which s-Lim exerts its antiarrhythmic effect, focusing on the blockade of ß-adrenoceptor (ß-AR) and its effects on various in vivo and in vitro parameters, including electrocardiogram (ECG) measurements, left ventricular developed pressure (LVDP), the ß-adrenergic pathway, sarcomeric shortening and L-type calcium current (ICa,L). In isolated hearts, 10 µM of s-Lim did not alter the ECG profile or LVPD. s-Lim increased the heart rate corrected QT interval (QTc) (10.8%) at 50 µM and reduced heart rate at the concentrations of 30 (12.4%) and 50 µM (16.6%). s-Lim (10 µM) also inhibited the adrenergic response evoked by isoproterenol (ISO) (1 µM) reducing the increased of heart rate, LVDP and ECG changes. In ventricular cardiomyocyte, s-Lim antagonized the effect of dobutamine by preventing the increase of sarcomeric shortening, demonstrating a similar effect to atenolol (blocker ß1-AR). In vivo, s-Lim antagonized the effect of ISO (agonists ß1-AR), presenting a similar effect to propranolol (a non-selective blocker ß-AR). In ventricular cardiomyocyte, s-Lim did not alter the voltage dependence for ICa,L activation or the ICa,L density. In addition, s-Lim did not affect changes in the ECG effect mediated by 5 µM forskolin (an activator of adenylate cyclase). In an in vivo caffeine/ISO-induced arrhythmia model, s-Lim (1 mg/kg) presented antiarrhythmic action verified by a reduced arrhythmia score, heart rate, and occurrence of ventricular premature beats and inappropriate sinus tachycardia. These findings indicate that the antiarrhythmic activity of s-Lim is related to blockade of ß-AR in the heart.

Sex-Specific Differences in Cardiovascular Adaptations and Risks in Elite Athletes: Bridging the Gap in Sports Cardiology.

BACKGROUND: The growing participation of women in competitive sports necessitates a comprehensive understanding of sex-specific cardiovascular adaptations and risks. Historically, research has predominantly focused on male athletes, leaving a gap in knowledge about the unique cardiovascular dynamics of female peers. HYPOTHESIS: we hypothesized that female athletes exhibit distinct cardiovascular adaptations and face different risks, influenced by physiological, hormonal, and structural differences. METHODS: A systematic review of the literature was conducted, analyzing studies on cardiovascular responses and adaptations in athletes. Data were extracted on hemodynamic changes, autonomic and neural reflex regulation, cardiac remodeling, and arrhythmias. Comparative analyses were performed to identify sex-specific patterns and discrepancies in cardiovascular health outcomes. RESULTS: We revealed considerable sex differences in cardiovascular adaptations to athletic training. Female athletes generally have longer QT intervals, greater sinoatrial node automaticity, and enhanced atrioventricular node function compared to males. They also exhibit lower sympathetic activity, lower maximal stroke volumes, and a tendency toward eccentric cardiac remodeling. Conversely, male athletes are more prone to concentric hypertrophy and higher incidences of bradyarrhythmia and accessory pathway arrhythmias. Female athletes are more likely to experience symptomatic atrial fibrillation and face higher procedural complications during catheter ablation. CONCLUSIONS: Our findings underscore the necessity for sex-specific approaches in sports cardiology. Recognizing and addressing these differences could enhance performance and reduce adverse cardiac events in athletes. Future research should focus on developing tailored screening, prevention, and treatment strategies to bridge the knowledge gap and promote cardiovascular health in both male and female athletes.

Roles of Atrial Arrhythmias in Triggering Torsade de Pointes in Patients With Acquired Long-QT Syndrome.

BACKGROUND: Little is known about the role of atrial arrhythmias (AAs) in triggering Torsade de Pointes (TdP) in patients with long-QT syndrome (LQTS). The aim of this study was to examine the contribution of AAs to the development of TdP in acquired LQTS patients. METHODS: The initiation patterns of 81 episodes of TdP obtained from 34 consecutive acute acquired LQTS patients (14 men, median age, 69 years; median QTc, 645.5 ms) with documented TdP were analyzed. The initiation mode of TdP was divided into 3 categories: (1) preceding short-long sequence (SLS); (2) sudden R-on-T phenomenon without preceding SLS; and (3) increased atrial rate. The patients were divided into 2 groups based on the presence or absence of AAs-induced TdP; AAs-induced (n=18) and non-AAs-induced (n=16) groups. The association of clinical/ECG characteristics and TdP frequency after initiating conventional therapy with AAs-induced TdP was evaluated. The groups were compared using the Mann-Whitney U test or Fisher exact test. RESULTS: AAs-induced group comprised 52.9% (18/34) of the patients studied. TdP was preceded by AAs-initiated SLSs in 41.2% (14/34) of the patients and was directly induced by R-on-T AAs (AAs coincidentally encountered a vulnerable repolarizing region during the T wave) in 23.5% (8/34). AAs triggered 48 (59.3%) of the 81 TdP episodes. AAs-initiated SLSs in 67.8% (40/59) of the SLS-induced TdP episodes. R-on-T AAs accounted for 23.5% (19/81) of the TdP episodes. AAs-induced group experienced TdP after initiating therapy more frequently than non-AAs-induced group (2.5 versus 1 event, P=0.008). AAs-induced group exhibited macroscopic T-wave alternans more frequently than non-AAs-induced group (6 versus 0, P=0.02). CONCLUSIONS: AAs play a key role in triggering TdP in more than half of patients with acute acquired LQTS and can increase TdP frequency after initiating therapy. Thus, AAs are not benign but rather can be life-threatening in patients with acute acquired LQTS.

Metformin and Atrial Fibrillation: A Systematic Review of Their Association.

Atrial fibrillation (AF) is a common cardiac arrhythmia with a significant impact on patient outcomes and healthcare systems. Given the rising incidence of AF with age and its association with conditions, such as diabetes, there is growing interest in exploring pharmacological interventions that might mitigate AF risk. Metformin, a widely prescribed antihyperglycemic agent for type 2 diabetes mellitus (T2DM), has demonstrated various cardiovascular benefits, including anti-inflammatory and antioxidative properties, leading to speculations about its potential role in AF prevention. This systematic review synthesizes findings from five studies examining the association between metformin use and AF risk in patients with T2DM. The review included a dynamic cohort study, three retrospective cohort studies, and a case report, all sourced from databases, such as PubMed, Embase, and the Cochrane Library. The results are mixed; while some studies suggest that metformin use is linked to a reduced incidence of AF, others report no significant association, particularly in postoperative settings. The largest cohort study highlighted a dose-response relationship, suggesting prolonged metformin use correlates with lower AF risk. Conversely, a case report raised concerns about metformin-induced lactic acidosis potentially triggering AF episodes. The review underscores the heterogeneity in study designs and outcomes, pointing to the need for more robust research to establish causality and clarify underlying mechanisms. Future studies should prioritize prospective designs and explore the pleiotropic effects of metformin on atrial remodeling and electrophysiology to better understand its potential role in AF prevention.

Current status of wearable cardioverter-defibrillator use in Japan.

Background: The current status of wearable cardiovascular defibrillators (WCD) use in Japan is unclear. Methods: Using a nationwide claims database of Japan, we assessed characteristics of patients using WCD and factors influencing subsequent implantable cardioverter-defibrillator (ICD) implantation. Results: In 1049 cases, those with prior cardiopulmonary arrest (CPA) or ventricular arrhythmia, cardiomyopathy, or device-related issues were more likely to require permanent ICDs, whereas females were less likely. Conclusions: Prior CPA or fatal arrhythmia, underlying cardiomyopathy, or device-related issues were associated with future permanent ICD implantation. These findings offer insights into the current status of WCD use in Japan.

Long-term follow-up of patients treated with laser balloon for atrial fibrillation: A high volume center experience with the first- and second-generation laser balloon.

Background: Laser balloon (LB) pulmonary vein isolation (PVI) is an established ablation technique for atrial fibrillation (AF). We report long-term follow-up and procedural data of LB-PVI and we compare the first and second LB generation. Methods: Patients undergoing LB ablation with first- (LB1) or second-generation LB (LB2) for AF were retrospectively enrolled and divided into two groups. Procedural endpoint was complete PVI. Clinical success was defined as no recurrence of AF/atrial tachycardia after a 90 days blanking period. Results: 538 patients were included (age 66 ± 10 years, 58% paroxysmal AF), 427 in LB1 and 111 in LB2. 2079 PVs were targeted and 2073 (99.7%) were successfully isolated; 2027 (97.5%) using solely the LB. Additional touch-up ablation was limited (46 PVs; 2.2%) with no difference between the groups. Procedural (LB1: 120 ± 33 minutes vs. LB2: 99 ± 22 min; p < .001) and fluoroscopy time (LB1: 11.2 ± 5 min vs. LB2: 8.5 ± 3 min; p < .001) were shorter with LB2. The complication rate was 8.9% (LB1: 10.1% vs. LB2: 4.5%; p = .067) with most complications resulting from the access site (21/48). Overall freedom from AF after 1-year was 73.7% (paroxysmal AF: 76.9%; persistent AF: 69.3%; p < .001) with no difference between the groups (LB1: 73.4% vs. LB2: 74.7%; p = .491). Conclusion: LB showed a high efficacy and acceptable safety, with numerically lower complication rates with the second-generation LB. Procedure and fluoroscopy times were shorter with LB2. Overall, 73.7% of patients were free from AF at 1-year, with comparable results among both generations.

Gastroesophageal reflux disease and risk for arrhythmias: a Mendelian randomization analysis.

Background: Clinical observations and epidemiological studies suggest a potential linkage between gastroesophageal reflux disease (GERD) and arrhythmias, yet the underlying mechanism remains elusive. This study investigates the causal relationship between GERD and four types of arrhythmia through a genetic lens, employing Mendelian randomization analysis to elucidate the directionality of these associations. Methods: Selected single nucleotide polymorphisms (SNPs) from genome-wide association study (GWAS) data were utilized as instrumental variables. The inverse variance weighting (IVW) method, MR-Egger regression analysis, and the weighted median method were employed in two-sample Mendelian randomization analysis. Horizontal pleiotropy was detected and corrected using the MR-PRESSO test and MR-Egger regression. The stability and reliability of the Mendelian randomization results were assessed using the leave-one-out method, Cochran's Q test, and funnel plots. The causal relationship between GERD and four types of arrhythmias was evaluated using the odds ratio (OR). Results: IVW results indicated that GERD could increase the risk of arrhythmias. A one standard deviation increases in the logarithmically transformed GERD score resulted in a 34% increase in the risk of arrhythmia (OR = 1.34; 95% CI 1.19-1.51; p = 1.66E-06). No significant correlation was found between GERD and other arrhythmias. Conclusion: A causal relationship exists between GERD and arrhythmias, suggesting that GERD increases the risk of developing these arrhythmias.

A pilot study of the proarrhythmic effects of pimobendan injection in clinically healthy cats.

Pimobendan is not currently approved for use in cats, although its usefulness in feline hypertrophic cardiomyopathy has been suggested. Reports indicate an increase in arrhythmic events following oral administration to healthy cats. Given the greater potency of intravenous administration compared to oral intake, it is conceivable that the incidence of arrhythmias may be increased following pimobendan injection. Therefore, this study aimed to investigate the proarrhythmic effects of pimobendan injection in cats. Five clinically healthy cats underwent physical examination, echocardiography, blood pressure measurements, and 24-hour Holter electrocardiography immediately before and after receiving pimobendan as an intravenous bolus dose of 0.15 mg/kg twice daily for 3 days. Additionally, a 24-hour Holter electrocardiography recording was conducted on the third day of pimobendan or placebo IV administration to assess heart rate, arrhythmias, and heart rate variability. Following pimobendan administration, there was a significant increase in total 24-hour heart rate. Echocardiography revealed a significant increase in mitral valve annulus systolic velocity (S') on the ventricular septal wall side, indicative of enhanced contractility. Only one cat exhibited paroxysmal ventricular tachycardia and an increase in the frequency of arrhythmic events. Conversely, in the remaining cats, a decreasing trend in the number of arrhythmias was observed. These findings indicate that intravenous administration of pimobendan may not be implicated in the onset of arrhythmias. Nevertheless, further research is warranted to explore the effects of intravenous pimobendan administration in cats with myocardial disease.

Management of ultrarare inherited arrhythmia syndromes.

Ultrarare inherited arrhythmia syndromes are increasingly diagnosed due to increased awareness as well as increased availability and reduced cost of genetic testing. Yet by definition, their rarity and heterogeneous expression makes development of evidence-based management strategies more challenging, typically employing strategies garnered from similar genetic cardiac disorders. For the most part, reliance on anecdotal experiences, expert opinion, and small retrospective cohort studies is the only means to diagnose and treat these patients. Here we review the management of specific ultrarare inherited arrhythmic syndromes together with the genetic and molecular basis, which will become increasingly important with the development of targeted therapies to the correct the biological basis of these disorders.

Zero-fluoroscopy catheter ablation of premature ventricular contractions: comparative outcomes from the right ventricular outflow tract and other ventricular sites.

BACKGROUND: The three-dimensional electroanatomic mapping (EAM) system allows performing catheter ablation (CA) without fluoroscopy in patients with premature ventricular contractions (PVCs). The right ventricle outflow tract (RVOT) location is favorable for performing zero-fluoroscopy CA. Non-RVOT zero-fluoroscopy CA is a challenging procedure. The study aimed to evaluate the efficacy and safety of zero-fluoroscopy CA using the EAM in patients with PVCs from RVOT and non-RVOT. METHODS: Completely zero-fluoroscopy CA of PVCs guided by EAM was performed in 107 patients with PVCs. 54 patients underwent zero-fluoroscopy RVOT CA. The remaining 53 patients underwent zero-fluoroscopy non-RVOT CA. Demographic and clinical baseline characteristics, procedure parameters, and follow-up were obtained from medical records. Primary outcomes were the acute and the permanent success rate (12-month follow-up), complications, and procedure time. RESULTS: There were no significant differences between groups regarding baseline characteristics. Acute procedural success was achieved in 52 patients (94,44%) in the RVOT zero-fluoroscopy CA group and in 45 patients (86,54%) in the non-RVOT zero-fluoroscopy CA group (ns). A long-term success rate was achieved in 50 patients (90,74%) in the RVOT zero-fluoroscopy CA group and in 44 patients (84,62%) in the non-RVOT zero-fluoroscopy CA group (ns). The median procedure time was 80.5 minutes in the RVOT group and 90 minutes in the non-RVOT group (ns). There were two complications in the non-RVOT group (ns). CONCLUSIONS: There were no differences in procedure time efficacy and safety zero-fluoroscopy ablation between RVOT and non-RVOT locations. Non-fluoroscopy CA of PVCs is a feasible, safe, and efficient procedure.