Background-There is a lack of understanding of the substrate for microreentrant circuits and triggered activity of the pulmonary vein (PV) muscle sleeves and atria, in patients with atrial fibrillation (AF).

BackgroundWe previously reported that IKAS are heterogeneously upregulated in failing rabbit ventricles and play an important role in arrhythmogenesis. This study goal is to test the hypothesis that subtype 2 of the small‐conductance Ca2+ activated K+ (SK2) channel and apamin‐sensitive K+ currents (IKAS) are upregulated in failing human ventricles.Methods and ResultsWe studied 12 native hearts from transplant recipients (heart failure [HF] group) and 11 ventricular core biopsies from patients with aortic stenosis and normal systolic function (non‐HF group). IKAS and action potential were recorded with patch‐clamp techniques, and SK2 protein expression was studied by Western blotting. When measured at 1 μmol/L Ca2+ concentration, IKAS was 4.22 (median) (25th and 75th percentiles, 2.86 and 6.96) pA/pF for the HF group (n=11) and 0.98 (0.54 and 1.72) pA/pF for the non‐HF group (n=8, P=0.008). IKAS was lower in the midmyocardial cells than in the epicardial and the endocardial cells. The Ca2+ dependency of IKAS in HF myocytes was shifted leftward compared to non‐HF myocytes (Kd 314 versus 605 nmol/L). Apamin (100 nmol/L) increased the action potential durations by 1.77% (−0.9% and 7.3%) in non‐HF myocytes and by 11.8% (5.7% and 13.9%) in HF myocytes (P=0.02). SK2 protein expression was 3‐fold higher in HF than in non‐HF.ConclusionsThere is heterogeneous upregulation of IKAS densities in failing human ventricles. The midmyocardial layer shows lower IKAS densities than epicardial and endocardial layers of cells. Increase in both Ca2+ sensitivity and SK2 protein expression contributes to the IKAS upregulation.

Introduction-Myocardial infarction (MI) results in cardiac nerve sprouting in the myocardium. Whether or not similar neural remodeling occurs in the stellate ganglia (SG) is unknown. We aimed to test the hypothesis that MI induces bilateral SG nerve sprouting.

Catheter ablation has become the curative treatment for various cardiac arrhythmias, including ventricular tachycardia and atrial fibrillation, leading to more challenging procedures, prolonged fluoroscopy exposure and the need for stable and reproducible catheter movement. In the last decade, remotely-controlled catheter ablation has emerged as a novel concept to improve catheter manoeuvrability and stability. This has the potential to increase procedural success, decrease procedure time and minimise catheter-related complications. To date, two remote navigation systems (Niobe from Stereotaxis and Sensei from Hansen Medical) are commercially available based on magnetic and mechanical driven forces, respectively. Both have shown promise but also shortcomings during clinical evaluation. Recently, two new systems, CGCIMaxwell from Magnetecs and Amigo from Catheter Robotics, have shown promising results in animals. They are under clinical evaluation and are also based on magnetic and mechanical driven forces, respectively. This article describes the basic principles of the systems, summarises their respective published experiences during mapping and ablation procedures, their current clinical applications and future directions.

The purpose of the current study was to compare right ventricular (RV) myocardial wall velocities (tissue Doppler imaging) and strain rate imaging (SRI) parameters with conventional echocardiographic indices evaluating RV function in chronic obstructive pulmonary disease (COPD) patients.In total, 39 patients with COPD and 22 healthy subjects were included in the current study. Seventeen patients had pulmonary artery pressure ,35 mmHg (group I) and 22 patients had pulmonary artery pressure .35 mmHg (group II). Tissue Doppler imaging, strain and strain rate (SR) values were obtained from RV free wall (FW) and interventricular septum. Respiratory function tests were performed (forced expiratory volume in one second/vital capacity (FEV1/VC) and carbon monoxide diffusion lung capacity per unit of alveolar volume (DL,CO/VA)).Strain/SR values were reduced in all segments of group II patients compared with group I patients and controls with lowest values at basal FW site. A significant relationship was shown between peak systolic SR at basal FW site and radionuclide RV ejection fraction. A significant relationship was shown between peak systolic SR at basal FW site and DL,CO/VA and FEV1/VC.In conclusion, in chronic obstructive pulmonary disease patients, strain rate imaging parameters can determine right ventricular dysfunction that is complementary to conventional echocardiographic indices and is correlated with pulmonary hypertension and respiratory function tests.