Characteristics of virtual unipolar electrograms for detecting isthmus block during radiofrequency ablation of typical atrial flutter

AbstractObjectivesThe purpose of this study was to investigate the characteristics of the second component of local virtual unipolar electrograms recorded at the ablation line during coronary sinus (CS) pacing after radiofrequency ablation (RFA) of the cavotricuspid isthmus (CTI) for typical atrial flutter (AFL).BackgroundRadiofrequency ablation of the CTI can produce local double potentials at the ablation line. The second component of unipolar electrograms represents the approaching wavefront in the right atrium opposite the pacing site. We hypothesized that the morphologic characteristics of the second component of double potentials would be useful in detecting complete CTI block.MethodsRadiofrequency ablation of the CTI was performed in 52 patients (males = 37, females = 15, 62 ± 12 years) with typical AFL. The noncontact mapping system (Ensite 3000, Endocardial Solutions, St. Paul, Minnesota) was used to guide RFA. Virtual unipolar electrograms along the ablation line during CS pacing after RFA were analyzed. Complete or incomplete CTI block was confirmed by the activation sequence on the halo catheter and noncontact mapping.ResultsThree groups were classified after ablation. Group I (n = 37) had complete bidirectional CTI block. During CS pacing, the second component of unipolar electrograms showed an R or Rs pattern. Group II (n = 12) had incomplete CTI block. The second component of unipolar electrograms showed an rS pattern. Group III (n = 3) had complete CTI block with transcristal conduction. The second component of unipolar electrograms showed an rSR pattern.ConclusionsA predominant R-wave pattern in the second component of unipolar double potentials at the ablation line indicates complete CTI block, even in the presence of transcristal conduction

Ventricular divergence correlates with epicardial wavebreaks and predicts ventricular arrhythmia in isolated rabbit hearts during therapeutic hypothermia

INTRODUCTION: High beat-to-beat morphological variation (divergence) on the ventricular electrogram during programmed ventricular stimulation (PVS) is associated with increased risk of ventricular fibrillation (VF), with unclear mechanisms. We hypothesized that ventricular divergence is associated with epicardial wavebreaks during PVS, and that it predicts VF occurrence. METHOD AND RESULTS: Langendorff-perfused rabbit hearts (n = 10) underwent 30-min therapeutic hypothermia (TH, 30°C), followed by a 20-min treatment with rotigaptide (300 nM), a gap junction modifier. VF inducibility was tested using burst ventricular pacing at the shortest pacing cycle length achieving 1:1 ventricular capture. Pseudo-ECG (p-ECG) and epicardial activation maps were simultaneously recorded for divergence and wavebreaks analysis, respectively. A total of 112 optical and p-ECG recordings (62 at TH, 50 at TH treated with rotigaptide) were analyzed. Adding rotigaptide reduced ventricular divergence, from 0.13±0.10 at TH to 0.09±0.07 (p = 0.018). Similarly, rotigaptide reduced the number of epicardial wavebreaks, from 0.59±0.73 at TH to 0.30±0.49 (p = 0.036). VF inducibility decreased, from 48±31% at TH to 22±32% after rotigaptide infusion (p = 0.032). Linear regression models showed that ventricular divergence correlated with epicardial wavebreaks during TH (p<0.001). CONCLUSION: Ventricular divergence correlated with, and might be predictive of epicardial wavebreaks during PVS at TH. Rotigaptide decreased both the ventricular divergence and epicardial wavebreaks, and reduced the probability of pacing-induced VF during TH

Current and state of the art on the electrophysiologic characteristics and catheter ablation of arrhythmogenic right ventricular dysplasia/cardiomyopathy

AbstractArrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited genetic disease caused by defective desmosomal proteins, and it has typical histopathological features characterized by predominantly progressive fibro-fatty infiltration of the right ventricle. Clinical presentations of ARVD/C vary from syncope, progressive heart failure (HF), ventricular tachyarrhythmias, and sudden cardiac death (SCD). The 2010 modified Task Force criteria were established to facilitate the recognition and diagnosis of ARVD/C. An implantable cardiac defibrillator (ICD) remains to be the cornerstone in prevention of SCD in patients fulfilling the diagnosis of definite ARVD/C, especially among ARVD/C patients with syncope, hemodynamically unstable ventricular tachycardia (VT), ventricular fibrillation, and aborted SCD. Further risk stratification is clinically valuable in the management of patients with borderline or possible ARVD/C and mutation carriers of family members. However, given the entity of heterogeneous penetrance and non-uniform phenotypes, the standardization of clinical practice guidelines for at-risk individuals will be the next frontier to breakthrough.Antiarrhythmic drugs are prescribed frequently to patients experiencing frequent ventricular tachyarrhythmias and/or appropriate ICD shocks. Amiodarone is the recommended drug of choice. Radiofrequency catheter ablation (RFCA) has been demonstrated to effectively eliminate the drug-refractory VT in patients with ARVD/C. However, the efficacy and clinical prognosis of RFCA via endocardial approach alone was disappointing prior to the era of epicardial approach. In recent years, it has been proven that the integration of endocardial and epicardial ablation by targeting the critical isthmus or eliminating abnormal electrograms within the diseased substrates could yield higher acute success and lower recurrence of ventricular tachyarrhythmias during long-term follow-up. Heart transplantation is the final option for patients with extensive disease, biventricular HF with uncontrollable hemodynamic compromise, and refractory ventricular tachyarrhythmias despite aggressive medical and ablation therapies

Signal-averaged electrocardiography as a noninvasive tool for evaluating the ventricular substrate in patients with nonischemic cardiomyopathy: reassessment of an old tool

IntroductionSignal-averaged electrocardiography (SAECG) provides diagnostic and prognostic information regarding cardiac diseases. However, its value in other nonischemic cardiomyopathies (NICMs) remains unclear. This study aimed to investigate the role of SAECG in patients with NICM.Methods and resultsThis retrospective study included consecutive patients with NICM who underwent SAECG, biventricular substrate mapping, and ablation for ventricular arrhythmia (VA). Patients with baseline ventricular conduction disturbances were excluded. Patients who fulfilled at least one SAECG criterion were categorized into Group 1, and the other patients were categorized into Group 2. Baseline and ventricular substrate characteristics were compared between the two groups. The study included 58 patients (39 men, mean age 50.4 ± 15.5 years), with 34 and 24 patients in Groups 1 and 2, respectively. Epicardial mapping was performed in eight (23.5%) and six patients (25.0%) in Groups 1 and 2 (p = 0.897), respectively. Patients in Group 1 had a more extensive right ventricular (RV) low-voltage zone (LVZ) and scar area than those in Group 2. Group 1 had a larger epicardial LVZ than Group 2. Epicardial late potentials were more frequent in Group 1 than in Group 2. There were more arrhythmogenic foci within the RV outflow tract in Group 1 than in Group 2. There was no significant difference in long-term VA recurrence.ConclusionIn our NICM population, a positive SAECG was associated with a larger RV endocardial scar, epicardial scar/late potentials, and a higher incidence of arrhythmogenic foci in the RV outflow tract

EHRA expert consensus document on the management of arrhythmias in frailty syndrome, endorsed by the Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Latin America Heart Rhythm Society (LAHRS), and Cardiac Arrhythmia Society of Southern Africa (CASSA).

There is an increasing proportion of the general population surviving to old age with significant chronic disease, multi-morbidity, and disability. The prevalence of pre-frail state and frailty syndrome increases exponentially with advancing age and is associated with greater morbidity, disability, hospitalization, institutionalization, mortality, and health care resource use. Frailty represents a global problem, making early identification, evaluation, and treatment to prevent the cascade of events leading from functional decline to disability and death, one of the challenges of geriatric and general medicine. Cardiac arrhythmias are common in advancing age, chronic illness, and frailty and include a broad spectrum of rhythm and conduction abnormalities. However, no systematic studies or recommendations on the management of arrhythmias are available specifically for the elderly and frail population, and the uptake of many effective antiarrhythmic therapies in these patients remains the slowest. This European Heart Rhythm Association (EHRA) consensus document focuses on the biology of frailty, common comorbidities, and methods of assessing frailty, in respect to a specific issue of arrhythmias and conduction disease, provide evidence base advice on the management of arrhythmias in patients with frailty syndrome, and identifies knowledge gaps and directions for future research