The myotonic dystrophies are multisystem disorders characterized by progressive skeletal muscle weakness, myotonia, cataracts, endocrine abnormalities, cognitive impairment, and cardiomyopathy. Myotonic dystrophy type 1 (DM1) is the most common of the myotonic dystrophies. The cardiac-specific phenotypes of DM1 include progressive atrioventricular conduction delay, atrial and ventricular arrhyt...

BACKGROUND We recently reported a mutation in the PRKAG2 gene to be responsible for a familial syndrome of ventricular preexcitation, atrial fibrillation, conduction defects, and cardiac hypertrophy. We now report a novel mutation in PRKAG2 causing Wolff-Parkinson-White syndrome and conduction system disease with onset in childhood and the absence of cardiac hypertrophy. METHODS AND RESULTS D...

The cardiac conduction system (CCS) initiates and coordinately propagates the electrical impulse to orchestrate the heartbeat. It consists of a set of interconnected components with shared properties. A better understanding of the origin and specification of CCS lineages has allowed us to better comprehend the etiology of CCS disease and has provided leads for development of therapies. A variet...

Cardiac electrophysiologic derangements often coexist with disorders of the circulatory system. Capturing and diagnosing arrhythmias and conduction system disease may lead to a change in diagnosis, clinical management and patient outcomes. Standard 12-lead electrocardiogram (ECG), Holter monitors and event recorders have served as useful diagnostic tools over the last few decades. However, thei...

Specialized fiber electrograms were recorded from selected sites along the His bundle and bundle branches during open-heart surgery in 26 patients. The heart was then paced from the same recording sites. Stimuli applied to the proximal His bundle recording site always resulted in His bundle pacing, which was characterized by a stimulus artifact-to-QRS interval which equaled or very nearly equal...

The contraction pattern of the heart relies on the activation and conduction of the electrical impulse. Perturbations of cardiac conduction have been associated with congenital and acquired arrhythmias as well as cardiac arrest. The pattern of conduction depends on the regulation of heterogeneous gene expression by key transcription factors and transcriptional enhancers. Here, we assessed the g...

The heterogeneous tissues of the cardiac pacemaking and conduction system are responsible for setting, maintaining and coordinating the rhythmic pumping of the heart (reviewed Thompson et al., 1995; Moorman et al., 1998; Gourdie et al., 1999). Anomalous development of this specialized network has been implicated in pediatric arrhythmia and other congenital abnormalities of cardiac activation (S...

The cardiac specialized conduction tissue was studied by serial sectioning in 13 cases of situs ambiguus. In four cases of right isomerism, we found paired sinus nodes in relation to a crista terminalis, and in each case a sling of conduction tissue between two atrioventricular nodes was present regardless of the ventricular morphology or cardiac position. In the cases with left isomerism, the ...

The cardiac conduction system (CCS) is a specialized tissue network that initiates and maintains a rhythmic heartbeat. The CCS consists of several functional subcomponents responsible for producing a pacemaking impulse and distributing action potentials across the heart in a coordinated manner. The formation of the distinct subcomponents of the CCS occurs within a precise temporal and spatial f...

HF-1 b, an SP1 -related transcription factor, is preferentially expressed in the cardiac conduction system and ventricular myocytes in the heart. Mice deficient for HF-1 b survive to term and exhibit normal cardiac structure and function but display sudden cardiac death and a complete penetrance of conduction system defects, including spontaneous ventricular tachycardia and a high incidence of ...