The Cardiac Conduction System
The intrinsic conduction system of the heart is comprised of several specialized subpopulations of cells that either spontaneously generate electrical activity (pacemaker cells) or preferentially conduct this activity throughout the chambers in a coordina
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Timothy G. Laske, Maneesh Shrivastav, and Paul A. Iaizzo
Abstract
The intrinsic conduction system of the heart is comprised of several specialized subpopulations of cells that either spontaneously generate electrical activity (pacemaker cells) or preferentially conduct this activity throughout the chambers in a coordinated fashion. This chapter will discuss the details of this known anatomy as well as put such discoveries into a historical context. The cardiac action potential underlies signaling within the heart, and the various populations of myocytes will elicit signature waveforms. The recording or active sensing of these potentials is important in both research and clinical arenas. This chapter aims to present a basic understanding of the cardiac conduction system to provide the reader with a foundation for future research and reading on this topic. The information in this chapter is not comprehensive and should not be used to make decisions relating to patient care. Keywords
Cardiac conduction • Sinoatrial node • Depolarization • Atrioventricular node • Electrophysiology • Cardiac action potential • Gap junction
Electronic supplementary material: The online version of this chapter (doi:10.1007/978-3-319-19464-6_13) contains supplementary material, which is available to authorized users. Videos can also be accessed at http://link.springer.com/book/10.1007/978-3-319-19464-6_13. T.G. Laske, PhD (*) Department of Surgery, University of Minnesota, Minneapolis, MN, USA Medtronic plc, 8200 Coral Sea Street NE, MVS 46, Minneapolis, MN 55112, USA e-mail: [email protected] M. Shrivastav, PhD Medtronic plc, 8200 Coral Sea Street NE, MVS 46, Minneapolis, MN 55112, USA P.A. Iaizzo, PhD Department of Surgery, University of Minnesota, Minneapolis, MN, USA
13.1 Introduction Orderly contractions of the atria and ventricles are regulated by the transmission of electrical impulses that pass through an intricate network of modified cardiac muscle cells, the cardiac conduction system. These cells are interposed within the contractile myocardium. This intrinsic conduction system is comprised of several specialized subpopulations of cells that spontaneously generate electrical activity (pacemaker cells) and/or preferentially conduct this activity throughout the heart. Following an initiating activation (or depolarization) within the myocardium, this electrical excitation spreads throughout the heart in a rapid and highly coordinated fashion. This system of cells also functionally controls the timing
© Springer International Publishing Switzerland 2015 P.A. Iaizzo (ed.), Handbook of Cardiac Anatomy, Physiology, and Devices, DOI 10.1007/978-3-319-19464-6_13
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of the transfer of activity between the atrial and ventricular chambers. Interestingly, a common global architecture is present in mammals, but significant interspecies differences exist at the histologic level [1, 2] (see also Chap. 6). Discoveries relating to this intrinsic conduction system within the heart are relatively recent relative to cardi
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