Editing Cardiac catheterization (section)

===Pacemakers and defibrillators===
[[File:X-ray of pacemaker with right atrial and ventricular lead.jpg|thumb|350px|Posteroanterior and lateral [[chest radiograph]]s of a pacemaker with normally located leads in the right atrium (white arrow) and right ventricle (black arrowhead), respectively.]]

Placement of internal [[Artificial cardiac pacemaker|pacemaker]]s and [[Implantable cardioverter-defibrillator|defibrillator]]s are done through catheterization as well. An exception to this is placement of electrodes on the outer surface of the heart (called epicardial electrodes). Otherwise, electrodes are placed through the venous system into the heart and left there permanently. Typically, these devices are placed in the left upper chest and enter the left [[subclavian vein]] and electrodes are placed in the right atrium, right ventricle, and coronary sinus (for the left ventricle stimulation).{{citation needed|date=March 2021}}