A 21st century view of the anatomy of the cardiac conduction system

Since the discovery of the major components of the cardiac conduction system (CCS) by the early 20th century we have seen many technological advancements that have allowed immense insight into the CCS tissues. In this review we will discuss how these innovation steps in imaging have been used to enhance our knowledge and understanding of the CCS. We have seen the development of electron microscopy, immunohistochemistry, confocal microscopy, magnetic resonance imaging, micro-computed tomography, and optical coherence tomography, each of which have been used in studies related to the CCS and its function in health and disease. These techniques have allowed us to generate detailed three-dimensional geometries of the CCS, fibre alignment, protein expression information, cell structure and organisation, and how these are affected in cardiac disease and contribute to cardiac dysfunction. Enhanced imaging techniques have provided great insight into the CCS components and changes with disease that can contribute directly to our understanding why the heart beats, diagnostic development, therapeutic, pharmacological and surgical methods, and the improvement of computational modelling studies.