ABSTRACT
Electrodes can be endocardial or epicardial. Endocardial (transvenous) electrodes are placed into the right ventricle through a branch of the cranial vena cava, and require a higher threshold potential to stimulate a beat. Epicardial-myocardial electrodes are either sutured or screwed into the myocardium of the ventricle. Less energy is required to initiate a heartbeat and the lifespan of the power source is increased. Either type of electrode may be unipolar or bipolar.
