Noun
The membrane lining the cavities of the heart.
Source: Webster's dictionaryIt involves a catheter with electrodes probing the endocardium, the inside of the heart, and testing the conduction pathways and electrical activity of individual areas of the heart. Source: Internet
These purkinje fibers (p-fibers) found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the heart to contract. citation The purkinje cells are mostly found within both the endocardium and the sub-endocardium. Source: Internet
The innermost layer of the heart is called the endocardium. Source: Internet