The heterogeneous tissues of the pacemaking and conduction system comprise the “smart
components” of the heart, responsible for setting, maintaining, and coordinating the rhythmic
pumping of cardiac muscle. Over the last few years, a wealth of new information has been
collected about the unique genetic and phenotypic characteristics expressed by these
tissues during cardiac morphogenesis. More recently, genetically modified viruses,
mutational analysis, and targeted transgenesis have enabled even more precise resolution …