Elucidation of Complex Atrial Tachycardia Activation in a Patient with Tetralogy of Fallot Using Omnipolar Mapping Technology: A Case Report.

In this case report, omnipolar mapping, a unique technology, was used to analyze complex atrial arrhythmias in an adult with congenital heart disease. Our patient had surgically corrected tetralogy of Fallot and presented with highly symptomatic atrial arrhythmias. A successful ablation was performed with standard bipolar mapping techniques. However, due to the complex nature of the substrate and arrhythmias in this patient, bipolar arrhythmia maps were difficult to interpret, and ablation lesions were delivered based on inference and "educated guesses." An offline re-analysis with omnipolar technology (OT) research software, days after the procedure was performed, revealed details not seen with traditional mapping and explained why the delivered lesions were effective. The findings of this retrospective analysis are provocative, suggesting that OT may increase the accuracy and efficiency of mapping and ablation of complex arrhythmias. Further investigation using commercially released OT in real time is needed.

Landiolol for Treating Arrhythmias: A State-of-The-Art Review.

This article provides a state-of-the-art review on landiolol, a medication that was recently submitted for 7 approvals. Focusing on its pharmacology, pharmacokinetics, and pharmacodynamics, the analysis underscores landiolol's unique attributes compared to conventional beta-blockers, particularly esmolol. As a sympatholytic agent, landiolol exhibits a short half-life, high cardioselectivity, and minimal impact on blood pressure, setting it apart in the realm of arrhythmia treatment. The review explores landiolol's potential applications, emphasizing scenarios where other beta-blockers may be limited. A detailed examination of its efficacy in preventing postoperative atrial fibrillation reveals promising results from clinical trials, suggesting its utility in diverse surgical settings. Additionally, the article delves into landiolol's role in rate control for atrial fibrillation/flutter, treatment of ventricular tachycardia/fibrillation, and its use in managing sepsis-related tachyarrhythmias. The evolving landscape of landiolol's applications extends beyond cardiac care, including potential anti-inflammatory, antioxidative, analgesic, and anticancer effects. While the outcomes from various studies are promising, challenges persist, requiring further research to optimize dosing strategies, identify optimal patient populations, and elucidate mechanisms underlying its diverse effects. The potential expansion of landiolol's applications highlights the importance of ongoing clinical investigation, offering a promising avenue for enhancing arrhythmia management and addressing broader medical needs.

Lead Extraction-Indications, Procedure, and Future Directions.

Cardiac implantable electronic device (CIED) implantation has steadily increased in the United States owing to increased life expectancy, better access to health care, and the adoption of updated guidelines. Transvenous lead extraction (TLE) is an invasive technique for the removal of CIED devices, and the most common indications include device infections, lead failures, and venous occlusion. Although in-hospital and procedure-related deaths for patients undergoing TLE are low, the long-term mortality remains high with 10-year survival reported close to 50% after TLE. This is likely demonstrative of the increased burden of comorbidities with aging. There are guidelines provided by various professional societies, including the Heart Rhythm Society, regarding indications for lead extraction and management of these patients. In this paper, we will review the indications for CIED extraction, procedural considerations, and management of these patients based upon the latest guidelines.

Brugada syndrome clinical update.

Brugada syndrome (BrS) was initially described in southeast Asians with a structurally normal heart presenting with polymorphic ventricular tachycardia and fibrillation. This condition is marked by J-point elevation ≥ 2 mm with coved-type ST segment elevation followed by negative T wave inversions in at least one precordial lead (V1 or V2) when other etiologies have been excluded. These changes on electrocardiogram (EKG) can either be spontaneous or manifest after sodium channel blockade. The worldwide prevalence of BrS is about 0.4%; however, it is higher in the Asian population at 0.9%. This article will review the current hypotheses regarding the pathophysiology, spectrum of clinical presentation, strategies for prevention of sudden cardiac death and the treatment for recurrent arrhythmias in BrS.

Unique technique to relieve left ventricular assist device electromagnetic interference with an implantable cardioverter defibrillator.

We introduced a simple technique to eliminate electromagnetic interference between a left ventricular assist device (LVAD) and an implantable cardioverter defibrillator (ICD). A 43-year-old male with heart failure and a reduced ejection fraction who had an ICD presented with decompensated heart failure and received an LVAD as a bridge to transplant. Remote monitoring showed persistent atrial fibrillation causing an inappropriate ICD shock leading to a decision to disable shock therapies. However, an in-office interrogation was unsuccessful due to electromagnetic interference. Patient was instructed to extend his arm above his head on the ipsilateral side of the ICD, thus increasing the distance between LVAD and ICD, eliminating the interaction to allow reprogramming of the device.

Role for risk factor treatment in the management of atrial fibrillation.

Atrial fibrillation is the most common arrhythmia in the world with continued rising prevalence, significant morbidity and mortality, and a substantial financial burden. It has been associated with numerous modifiable risk factors and chronic medical conditions. Treatment of these modifiable risk factors has improved rhythm control of atrial fibrillation as well as demonstrated cost-effectiveness. Primary prevention of underlying chronic disease should be incorporated into the treatment paradigm for AF. Comprehensive management with integrated care including the patient, allied health professionals, primary care physicians, and specialists will be needed to reverse the epidemiological trends, improve quality of life, and mortality.

The relationship between atypical antipsychotics drugs, QT interval prolongation, and torsades de pointes: implications for clinical use.

Introduction: Increased mortality has been observed in patients with mental health disorders. Specifically, exposure to antipsychotic medications conveys a greater than 2 fold risk of sudden death, thought to be mediated through effects on QT prolongation and risk of torsades de pointes.Areas covered: We review the association between antipsychotic drugs and sudden cardiac death, the physiologic basis for these associations, assessment of patients at risk, and strategies to minimize risk of sudden cardiac death.Expert opinion: Despite the prevalence of antipsychotic medication use for many decades, there remain considerable challenges in reducing the associated risk of sudden cardiac death. A structured algorithm that incorporates patient clinical factors and antipsychotic drug factors may improve risk assessment and reduce the risk of adverse cardiac events. Future advancements in genetics and artificial intelligence may allow for enhanced risk stratification and predicting response (efficacy and adverse effects) to therapy.

Catecholaminergic Polymorphic Ventricular Tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare congenital arrhythmogenic disorder induced by physical or emotional stress. It mainly affects children and younger adults and is characterized by rapid polymorphic and bidirectional ventricular tachycardia. Symptoms can include dizziness, palpitations, and presyncope, which may progress to syncope, hypotonia, convulsive movements, and sudden cardiac death. CPVT is the result of perturbations in Ca ion handling in the sarcoplasmic reticulum of cardiac myocytes. Mutations in the cardiac ryanodine receptor gene and the calsequestrin isoform 2 gene are most commonly seen in familial CPVT patients. Under catecholaminergic stimulation, either mutation can result in an excess Ca load during diastole resulting in delayed after depolarization and subsequent arrhythmogenesis. The current first-line treatment for CPVT is ß-blocker therapy. Other therapeutic interventions that can be used in conjunction with ß-blockers include moderate exercise training, flecainide, left cardiac sympathetic denervation, and implantable cardioverter-defibrillators. Several potential therapeutic interventions, including verapamil, dantrolene, JTV519, and gene therapy, are also discussed.

Ablation of long-standing persistent atrial fibrillation.

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in the clinical setting affecting nearly 6 million people in United States and the numbers are only expected to rise as the population continues to age. Broadly it is classified into paroxysmal, persistent and longstanding persistent AF. Electrical, structural and autonomic remodeling are some of the diverse pathophysiological mechanisms that contribute to the persistence of AF. Our review article emphasizes particularly on long standing persistent atrial fibrillation (LSPAF) aspect of the disease which poses a great challenge for electrophysiologists. While pulmonary vein isolation (PVI) has been established as a successful ablation strategy for paroxysmal AF, same cannot be said for LSPAF owing to its long duration, complexity of mechanisms, multiple triggers and substrate sites that are responsible for its perpetuation. The article explains different approaches currently being adopted to achieve freedom from atrial arrhythmias. These mainly include ablation techniques chiefly targeting complex fractionated atrial electrograms (CFAE), rotors, linear lesions, scars and even considering hybrid approaches in a few cases while exploring the role of delayed enhancement magnetic resonance imaging (deMRI) in the pre-procedural planning to improve the overall short and long term outcomes of catheter ablation.

Prevalence of Left Atrial Thrombus Detection by Transesophageal Echocardiography: A Comparison of Continuous Non-Vitamin K Antagonist Oral Anticoagulant Versus Warfarin Therapy in Patients Undergoing Catheter Ablation for Atrial Fibrillation.

OBJECTIVES: The purpose of this study is to determine whether patients on ≥4 weeks of continuous non-vitamin K antagonist oral anticoagulant (NOAC) therapy require transesophageal echocardiography (TEE) before catheter ablation of atrial fibrillation (AF) or atrial flutter and to compare rates of left atrial (LA) thrombus and dense spontaneous echocardiographic contrast (SEC) in patients on NOAC versus warfarin therapy. BACKGROUND: The impact of NOAC therapy on the rates of LA thrombus detection by TEE in patients undergoing catheter ablation of AF is unknown. METHODS: Initial TEEs for 388 patients (median age, 65 years; 74% male) on ≥4 weeks of continuous NOAC (n = 183) or warfarin therapy (n = 205) undergoing catheter ablation of AF and flutter were reviewed. RESULTS: After ≥4 weeks of therapy, the prevalence of LA thrombus and LA thrombus/dense SEC among patients on NOACs was 4.4% and 6.0%, respectively, which was comparable with that of patients on warfarin. LA thrombus rates among patients on dabigatran, rivaroxaban, and apixaban were 5.4%, 4.8%, and 0%, respectively (p = 0.46). Predictors of LA thrombus were congestive heart failure (odds ratio [OR]: 5.38; 95% confidence interval [CI]: 1.79 to 16.2; p = 0.003); and persistent AF (OR: 3.27; 95% CI: 1.06 to 10.2; p = 0.040). CONCLUSIONS: Despite ≥4 weeks of anticoagulation, the rate of LA thrombus in patients on NOACs before catheter ablation of AF or atrial flutter was 4.4%. This suggests that continuous NOAC therapy does not eliminate the need for TEE before catheter ablation of AF.

Differentiation of papillary muscle from fascicular and mitral annular ventricular arrhythmias in patients with and without structural heart disease.

BACKGROUND: Idiopathic left ventricular arrhythmias (VAs) and those caused by structural heart disease can originate from the papillary muscles, fascicles, and mitral annulus. Differentiation of these arrhythmias can be challenging because they present with a right bundle branch block morphology by electrocardiography. We sought to identify clinical, electrocardiographic, and electrophysiological features that distinguish these left VAs in patients with and without structural heart disease. METHOD AND RESULTS: Patients undergoing catheter ablation for papillary muscle, fascicular, or mitral annular VAs were studied. Demographic data and electrocardiographic and electrophysiological findings were analyzed. Fifty-two VAs in 51 patients (32 [63%] male; mean age 61±15 years) with papillary muscle (n=18), fascicular (n=15), and mitral annular (n=19) origins were studied. Patients with papillary muscle VAs were older and had higher prevalence of left ventricular dysfunction (67% versus 13% of fascicular VA patients [P=0.009]) and coronary artery disease (78% versus 37% of mitral annular VA patients [P=0.036]). Papillary muscle VAs were distinguished electrocardiographically from fascicular VAs by longer QRS durations and lower prevalence of r

Determination of standard electrode potential E(o) for chronic platinum and gold electrodes in rat muscle: implications for biosensors and the "anode" of bipolar pacing.

Pacemaker electrode surface modification by organosilane and organic self-assembled monolayer strategies creates a possible new variable in pacemaker electrode behavior. Because all of these chemical surface coatings are unstable at extremes of potential, the potential to which the electrode relaxes (between pacing pulses) becomes extremely important. The authors measured this potential for platinum (Pt) and gold (Au) relevant for their use as anode (or cathode) in a bipolar pacing system and from this potential the standard electrode potential, E(o) was determined. Thirty-Four determinations were made by a null current three-electrode potentiostatic technique of 2.45 mm2 platinum or gold electrodes implanted chronically in blood perfused muscle in a spontaneously breathing rat. Linear voltage sweeps were performed while monitoring current with voltage at null current determined repeatedly at varying scan rates and limits. Electrode potential varied between -388 +/- 19 mV (vs Ag/Ag+) for platinum and -388 +/- 55 mV for gold electrodes. Hysteresis was observed in all sweeps (P < 0.008, Fisher's exact) and measured 61 +/- 17 mV (anodic) and 25 +/- 3 mV (cathodic) with steep dependence on polarity (P < 0.001, t-test). The findings were independent of the materials' electronic work function. E(o) versus normal hydrogen electrode (NHE) were thus -166 mV (platinum) and -166 mV (gold). Because the most common bipolar system, uses platinum as anode, these results are directly applicable to current pacing technology. Provided low thresholds are achievable with novel surface modified electrodes, the small range of variation of E(o), and the particular mean value observed, are both compatible with function, provided care is used during electrode testing to avoid surface disruption. These results are significant also for biosensors that use similar surface modification methodologies.

Comparação de métodos de representação do segmento ST na detecção automática de isquemias miocárdicas / Comparison of methods for representing ST segments on automatic detection of myocardial ischemias

As doenças isquêmicas do coração constituem uma das principais causas de óbitos no Brasil. Os episódios isquêmicos manifestam-se no eletrocardiograma ambulatorial através de alterações no segmento ST e constituem um bom preditor de infarto do miocárdio e morte súbita. Este trabalho investiga quatro métodos de representação do segmento ST e compara seus desempenhos, vantagens e desvantagens na identificação automática de 165 episódios isquêmicos de 45 pacientes do European ST-T Database. O primeiro método utiliza um ponto do segmento ST, localizado a 104 ms da onda R de cada batimento. O segundo encontra dois pontos do segmento ST, dependentes do intervalo RR, e calcula a amplitude média do sinal compreendido entre estes. O terceiro analisa o coeficiente da primeira componente principal obtido a partir de uma transformação linear que considera vários exemplos de segmentos ST-T. O quarto método explora a capacidade de redução da dimensionalidade da análise de componentes principais, utilizando os seis primeiros coeficientes como entrada de uma rede neural feedforward/backpropagation que efetua a classificação automática dos segmentos. A saída da rede e os parâmetros fornecidos pelos outros métodos são considerados como séries temporais, sobre as quais é determinado o melhor limiar de detecção de episódios isquêmicos. Embora todos os métodos sejam eficientes para a detecção de alterações elevadas do segmento ST, o emprego da rede neural artificial fornece o melhor desempenho para alterações moderadas, com 83,64 por cento de sensibilidade e 75,41 por cento de valor preditivo positivo.