Radiofrequency balloon ablation: 1-year outcomes of the AURORA study.

Background: A novel irrigated radiofrequency balloon (RFB) for pulmonary vein isolation (PVI) integrated into a 3D mapping platform was recently launched.

Methods: Patients undergoing a first atrial fibrillation (AF) ablation at two German high-volume EP centers were included into the prospective AURORA registry. All patients underwent clinical follow-up (FU) at 90, 180, and 360 days following ablation including 48-h Holter ECGs.

PDE8 Inhibition and Its Impact on ICa,L in Persistent Atrial Fibrillation: Evaluation of PDE8 as a Potential Drug Target.

Atrial fibrillation (AF) poses a significant therapeutic challenge with drug interventions showing only limited success. Phosphodiesterases (PDE) regulate cardiac electrical stability and may represent an interesting target. Recently, PDE8 inhibition was proposed as an antiarrhythmic intervention by increasing L-type Ca 2+ current (I Ca,L ) and action potential duration (APD).

Pulsed-field- vs. cryoballoon-based pulmonary vein isolation: lessons from repeat procedures.

Aims: Pulsed-field ablation (PFA) is an emerging technology to perform pulmonary vein isolation (PVI). Initial data demonstrated high safety and efficacy. Data on long-term PVI durability and reconduction patterns in comparison to established energy sources for PVI are scarce.

Association of atrial mechanical dispersion with atrial fibrillation recurrence following catheter ablation: results of the ASTRA-AF pilot study.

Aims: For patients with symptomatic drug-refractory atrial fibrillation (AF), catheter ablation to achieve rhythm control is an important therapeutic option. The atrial mechanical dispersion measured as standard deviation of the time to peak strain (SD-TPS) is associated with the risk of AF recurrence following catheter ablation.

Methods: The study cohort prospectively enrolled n = 132 consecutive patients with paroxysmal (n = 88) or persistent AF (n = 44) presenting for de novo pulmonary vein isolation (PVI) and followed for 1 year.

Repeat pulmonary vein isolation and anterior line ablation using a novel point-by-point pulsed-field ablation system.

Background: Pulsed-field ablation (PFA) is a nonthermal energy source for ablation of cardiac arrhythmias. This study investigated the prospective outcomes of a novel PFA generator in conjunction with a commercially available, contact force-sensing, focal ablation catheter.

Objective: The purpose of this study was to assess the feasibility, safety, and lesion characteristics of point-by-point PFA in consecutive patients undergoing repeat ablation of atrial fibrillation (AF).

Human induced pluripotent stem cell-derived cardiomyocytes as an electrophysiological model: Opportunities and challenges-The Hamburg perspective.

Models based on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are proposed in almost any field of physiology and pharmacology. The development of human induced pluripotent stem cell-derived cardiomyocytes is expected to become a step forward to increase the translational power of cardiovascular research. Importantly they should allow to study genetic effects on an electrophysiological background close to the human situation.

Resting membrane potential is less negative in trabeculae from right atrial appendages of women, but action potential duration does not shorten with age.

Aims: The incidence of atrial fibrillation (AF) increases with age. Women have a lower risk. Little is known on the impact of age, sex and clinical variables on action potentials (AP) recorded in right atrial tissue obtained during open heart surgery from patients in sinus rhythm (SR) and in longstanding AF.

Regulation of APD and Force by the Na/Ca Exchanger in Human-Induced Pluripotent Stem Cell-Derived Engineered Heart Tissue.

The physiological importance of NCX in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is not well characterized but may depend on the relative strength of the current, compared to adult cardiomyocytes, and on the exact spatial arrangement of proteins involved in Ca2+ extrusion. Here, we determined NCX currents and its contribution to action potential and force in hiPSC-CMs cultured in engineered heart tissue (EHT). The results were compared with data from rat and human left ventricular tissue.

Muscarinic Receptor Activation Reduces Force and Arrhythmias in Human Atria Independent of IK,ACh.

In human hearts, muscarinic receptors (M-R) are expressed in ventricular and atrial tissue, but the acetylcholine-activated potassium current (IK,ACh) is expressed mainly in the atrium. M-R activation decreases force and increases electrical stability in human atrium, but the impact of IK,ACh to both effects remains unclear. We used a new selective blocker of IK,ACh to elaborate the contribution of IK,ACh to M-R activation-mediated effects in human atrium.

Regulation of basal and norepinephrine-induced cAMP and I in hiPSC-cardiomyocytes: Effects of culture conditions and comparison to adult human atrial cardiomyocytes.

Background: There is ongoing interest in generating cardiomyocytes derived from human induced pluripotent stem cells (hiPSC) to study human cardiac physiology and pathophysiology. Recently we found that norepinephrine-stimulated calcium currents (I) in hiPSC-cardiomyocytes were smaller in conventional monolayers (ML) than in engineered heart tissue (EHT). In order to elucidate culture specific regulation of β-adrenoceptor (β-AR) responses we investigated whether action of phosphodiesterases (PDEs) may limit norepinephrine effects on I and on cytosolic cAMP in hiPSC-cardiomyocytes.

Ca currents in cardiomyocytes: How to improve interpretation of patch clamp data?

Objectives: Variability of ion currents is major issue when used for significance testing. One of the simplest approach to reduce variability is normalization to cell membrane size. However, efficacy of Ca currents (I) normalization is unknown.

Regulation of I and force by PDEs in human-induced pluripotent stem cell-derived cardiomyocytes.

Background And Purpose: Phosphodiesterases (PDEs) are important regulators of β-adrenoceptor signalling in the heart. While PDE4 is the most important isoform that regulates I and force in rodent cardiomyocytes, the dominant isoform in adult human cardiomyocytes is PDE3.

Experimental Approach: Given the potential of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for biomedical research, this study characterized the contribution of PDE3 and PDE4 isoforms to the regulation of I and force in hiPSC-CMs in an engineered heart tissue (EHT) model.

Chronic intermittent tachypacing by an optogenetic approach induces arrhythmia vulnerability in human engineered heart tissue.

Aims: Chronic tachypacing is commonly used in animals to induce cardiac dysfunction and to study mechanisms of heart failure and arrhythmogenesis. Human induced pluripotent stem cells (hiPSC) may replace animal models to overcome species differences and ethical problems. Here, 3D engineered heart tissue (EHT) was used to investigate the effect of chronic tachypacing on hiPSC-cardiomyocytes (hiPSC-CMs).