TY - CHAP M1 - Book, Section TI - Chapter 17. Development of the Heart, with Particular Reference to the Cardiac Conduction Tissues A1 - Anderson, Robert H. A1 - Sizarov, Aleksander A1 - Moorman, Antoon F. M. A2 - Pahlm, Olle A2 - Wagner, Galen S. PY - 2011 T2 - Multimodal Cardiovascular Imaging: Principles and Clinical Applications AB - It is, perhaps, unfortunate that the myocytes that generate and dissipate the cardiac impulse throughout the myocardial body are known as the cardiac conduction tissues, because all myocytes within the heart possess the capacity to conduct. The alternative title, the "specialized tissues," is equally unfortunate, because from a developmental stance, as we will show, the so-called conducting tissues, in particular the nodal components, share important features with the myocytes of the primary heart tube. It is their so-called "working" partners that show more evidence of developmental specialization. In this chapter, therefore, we will describe the processes whereby the initial heart tube grows by addition of myocardium at both its venous and arterial pole, how it loops, and how eventually it becomes converted into the four-chambered organ. In this definitive structure, it is the sinus node that generates the cardiac impulse, this being propagated within the atrial musculature, delayed in the atrioventricular node, and then conducted rapidly to the ventricular myocardium through the atrioventricular bundle, its branches, and the ventricular ramifications known as Purkinje fibers. We will also discuss the fate of the more widespread areas of primary myocardium found in the developing heart because it is almost certainly the remnants of these areas in the postnatal heart that are the substrates for many cardiac arrhythmias. In contrast, with regard to perhaps the most important arrhythmia in the ageing population, namely atrial fibrillation, we will show how the pulmonary myocardial sleeves, known now to be the substrate for many forms of atrial fibrillation, are derived from so-called working rather than specialized conducting tissues. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/04/18 UR - accesscardiology.mhmedical.com/content.aspx?aid=8763644 ER -