English cardiac English English Electrical conduction system of the heart English cardiac English cardiac conducting pathway 心脏电传导系统 English cardiac English Electrical conduction system of the heart English conduction English English English Electrical conduction system of the heart English Heart Nodes cardiac conduction 心脏电传导系统 English Conduction English English Heart Nodes Heart Nodes English conduction English English English Electrical conduction system of the heart English English Electrical conduction system of the heart electrical conduction system of the heart Normal sinus rhythm English heart node signals