Cardiac fibrosis is characterized by the deposition of extracellular matrix (ECM) and mediated by cardiac fibroblasts via the renin-angiotensin system (RAS) and transforming growth factor beta (TGFβ) signaling pathways. Recognition of TGFβ by fibroblasts leads to myofibroblast differentiation as well as induction of ECM protein expression. An imbalance between proand anti-fibrotic signals resul...

Reactive oxygen species (ROS) are emerging as centre-stage players in cardiac functional regulation. ROS and Ca2+ signals converge at dyads, the structural and functional units of cardiac excitation–contraction coupling. These two prominent signalling systems are intertwined with ROS modulation of the entire Ca2+-signalling network, and vice versa. While constitutively generated homoeostatic RO...

Structural inhomogeneities in cardiac tissue have been associated with increased cellular repolarization alternans in animal experiments and increased T-wave alternans (TWA) in clinical studies. However, the effect of structural inhomogeneities on the relationship between cellular alternans and TWA has not been thoroughly investigated. We created 1-dimensional multicellular fiber models with an...

Homogeneity of recovery time protects against arrhythmias whereas dispersion of recovery time is arrhythmogenic. A single surface electrocardiographic QT interval gives no information on recovery time dispersion but the difference between the maximum and minimum body surface QT interval may be relevant. This hypothesis was tested by measuring the dispersion of the corrected QT interval (QTc) in...

Cardiomyocyte Ca2+ dictates cardiac contraction via excitation–contraction coupling (ECC) and excitation–transcription coupling. Adaptation to these processes also majorly contributes enhanced contractile function capacity following exercise training. Cytoplasmic release controls sarcomeric contraction, with important modulation by the voltage-sensitive plasma membrane L-type channel Ryanodine ...

Percutaneous septal ablation has emerged as a less invasive treatment of symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). In the past decade, the availability of this sophisticated technique has revived the interest of cardiologists in left ventricular outflow tract obstruction, which led to the recognition that most patients with HCM have the obstructive type. Follow-u...

Mycobacterial infections resulting from cardiac implantable electronic devices are rare, but as more devices are implanted, these organisms are increasingly emerging as causes of early-onset infections. We report a patient with an implantable cardioverter-defibrillator pocket and associated bloodstream infection caused by an organism of the Mycobacterium fortuitum group, and we review the liter...

Tachycardia-dependent QT/T alternans occurs in patients with the congenital or idiopathic form of long-QT syndrome (LQTS) and may presage the onset of polymorphic ventricular tachyarrhythmias. To examine the electrophysiological basis of arrhythmogenicity of QT/T alternans in LQTS, the tridimensional repolarization pattern of QT/T alternans was studied in the anthopleurin-A model of LQTS, a sur...