Nitroprusside modulates pulmonary vein arrhythmogenic activity

<p>Abstract</p> <p>Background</p> <p>Pulmonary veins (PVs) are the most important sources of ectopic beats with the initiation of paroxysmal atrial fibrillation, or the foci of ectopic atrial tachycardia and focal atrial fibrillation. Elimination of nitric oxide (NO) enhances cardiac triggered activity, and NO can decrease PV arrhythmogensis through mechano-electrical feedback. However, it is not clear whether NO may have direct electrophysiological effects on PV cardiomyocytes. This study is aimed to study the effects of nitroprusside (NO donor), on the ionic currents and arrhythmogenic activity of single cardiomyocytes from the PVs.</p> <p>Methods</p> <p>Single PV cardiomyocytes were isolated from the canine PVs. The action potential and ionic currents were investigated in isolated single canine PV cardiomyocytes before and after sodium nitroprusside (80 μM,) using the whole-cell patch clamp technique.</p> <p>Results</p> <p>Nitroprusside decreased PV cardiomyocytes spontaneous beating rates from 1.7 ± 0.3 Hz to 0.5 ± 0.4 Hz in 9 cells (P < 0.05); suppressed delayed afterdepolarization in 4 (80%) of 5 PV cardiomyocytes. Nitroprusside inhibited L-type calcium currents, transient outward currents and transient inward current, but increased delayed rectified potassium currents.</p> <p>Conclusion</p> <p>Nitroprusside regulates the electrical activity of PV cardiomyocytes, which suggests that NO may play a role in PV arrhythmogenesis.</p

An Observational, Prospective Survey Assessing the Control of Atrial Fibrillation in Asia Pacific: Rationale and Design of the RecordAF-AP Registry

Background The literature suggests that the prevalence of atrial fibrillation (AF) may be lower in Asian countries than in Western countries. Nevertheless, AF remains a significant public health problem in the region. The burden of AF, the experiences of previous trials and the lack of data on AF and its management in Asia Pacific highlight the need for a comprehensive prospective study of AF management. Methods The REgistry on Cardiac rhythm disORDers assessing the control of Atrial Fibrillation Asia Pacific (RecordAF-AP) is a prospective, observational survey of the management of recently diagnosed AF patients with 1-year follow-up in 8 countries across Asia Pacific. Eligible patients presenting with AF, treated or not, will be included in the registry and data will be recorded prospectively during follow-up visits at 6 and 12 months. Results RecordAF-AP will recruit more than 3000 patients. Study recruitment commenced in April 2009 and the final results anticipated at the end of 2011. Conclusions RecordAF-AP will assess the real-life management of AF patients in Asia Pacific, including a comparison of clinical outcomes in rhythm versus rate control strategies, providing much needed insight into the costs, treatment choices and clinical outcomes of AF patients in this region

Cardiovascular Imaging in the Management of Atrial Fibrillation

Atrial fibrillation (AF) is he most commonly encountered arrhythmia in clinical practice, with an overall prevalence of 0.4% in the general population. Recent advances in technology and in the understanding of the pathophysiology of AF have led to more definitive and potentially curative therapeutic approaches. Echocardiography has a well-established role in the assessment of cardiac structure and function and risk stratification, and has become an essential part of the guidelines for management of AF. The development of intracardiac echocardiography has led to real-time guidance of percutaneous interventions, including radiofrequency ablation and left atrial appendage closure procedures for patients with AF. Other imaging modalities, including computed tomography and magnetic resonance angiography, have allowed for more accurate measurement and better understanding of the cardiac anatomy. We review the impact of various imaging modalities in the evaluation and management of AF

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

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

Free-living marine nematodes community structure in the conservation area (Chaojing Park) and its adjacent area of Keelung, Taiwan

Studies conducted in the same seas or even study sites nearby each other, showed very different community structure, implying the patchiness of free-living marine nematodes which may be related to the sedimentary environment such as sediment type and food availability of the study area. This study was motivated by the concerns about the impacts of high level of anthropogenic activities on Chaojing Park (gazetted as Wanghaixiang’s Chao-Jing Bay Resource Conservation Area (WCJBRA) in 2016). The present study provides baseline knowledge of free-living marine nematode community structure in WCJBRA and identify potential marine nematodes as bioindicators to indicate possible impacts of the anthropogenic activities to the Chaojing Park. A total of 15 stations were selected in the subtidal zones of WCJBRA and its adjacent area. Marine nematode sample collection was carried out on the 13th and 14th of September 2019 using SCUBA diving technique. Results showed positive correlation between nematode density and medium sand (500μm-1.0mm). Presence of certain species such as Daptonema sp., Pomponema sp. and Innocuonema sp. indicates presence of disturbances in S12 and S13. Several species also showed potential to be introduced as indicator for healthy environment subjected to further studies on nematode-pollutants relationship, particularly on autecology as per se. Higher species diversity, H’ index of S1-S8 and S11 was categorised as Good Condition; followed by station with moderate species diversity index (S9, S10, S14 –Moderate Condition) zone; and lastly S12, S13 and S15 (Poor Condition)