Concepts of cardiac development have greatly influenced the description of the formation of the four-chambered vertebrate heart. Traditionally, the embryonic tubular heart is considered to be a composite of serially arranged segments representing adult cardiac compartments. Conversion of such a serial arrangement into the parallel arrangement of the mammalian heart is difficult to understand. L...

In 1906, Tawara published his treatise, recently translated from German to English,1 on the anatomy of the cardiac conduction system, which he elucidated through painstaking dissection and histological examination. In the following decades, the conduction system was generally understood and studied in anatomic and physiological terms. Most molecular biology focused on the genes and proteins tha...

BACKGROUND Reentry has been shown to be a mechanism of ventricular arrhythmias elicited by programmed premature stimulation in the subacute ischemic period of dogs subjected to myocardial infarction. The spatial distribution of refractoriness in these hearts has been shown to play an important part in the formation of functional arcs of conduction block during programmed ventricular stimulation...

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...

Since Keith and Flack's anatomical discovery of the sinoatrial node (SAN), the primary pacemaker of the heart, the question of how such a small SAN structure can pace the entire heart has remained for a large part unanswered. Recent advances in optical mapping technology have made it possible to unambiguously resolve the origin of excitation and conduction within the animal and human SAN. The c...

The tubular heart of tunicates is composed of a single layer of myoendothelial cells. The direction of contraction reverses every few minutes. The conduction times in both directions are the same. Conduction velocity was greatest in the middle of the arms of the V-shaped heart and slowest in the apex. The greater the heart length, the greater was the conduction velocity. The Q(10) of conduction...

Atrioventricular (AV) conduction was studied in anesthetized, open-chest, 1-35-day-old goats. Atrial, bundle of His, and ventricular bipolar electrograms were recorded, and the functional refractory periods of the AV conduction system and the ventricles were determined. Supraventricular premature excitation invaded the ventricles during their vulnerable period. This AV conduction property is di...

Electrical coupling between heart muscle cells is mediated by specialised regions of sarcolemmal interaction termed gap junctions. In previous work, we have demonstrated that connexin42, a recently identified gap-junctional protein, is present in the specialised conduction tissues of the avian heart. In the present study, the spatial distribution of the mammalian homologue of this protein, conn...

RATIONALE The clinically important atrioventricular conduction axis is structurally complex and heterogeneous, and its molecular composition and developmental origin are uncertain. OBJECTIVE To assess the molecular composition and 3D architecture of the atrioventricular conduction axis in the postnatal mouse heart and to define the developmental origin of its component parts. METHODS AND RE...