Lipp Vis Nursing ChaptLWBK1630_C02_p013-068

54  Chapter 2 • Cardiovascular Care

Understanding Pacemaker Codes First Letter The first letter of a pacemaker code identifies the heart chambers that are paced: V = Ventricle A = Atrium D = Dual (ventricle and atrium) O = None Second Letter The second letter signifies the heart chamber where the pacemaker senses the intrinsic activity: V = Ventricle A = Atrium D = Dual O = None Third Letter The third letter shows the pacemaker’s response to the intrinsic electrical activity it senses in the atrium or ventricle. inhibited depending on the mode and where intrinsic activity occurs) O = None (the pacemaker doesn’t change its mode in response to sensed activity) Fourth Letter The fourth letter signifies the rate modulation ability of the pacemaker (attempt to replicate the ability of a normal heart to increase heart rate in response to T = Triggers pacing I = Inhibits pacing D = Dual (can be triggered or

Permanent Pacemaker Systems Permanent pacemakers are fully implanted in the body and connected to the heart by one or two electrode leads. The pacemaker is powered by solid-state lithium batteries, which usually last 5 to 10 years. Pacemakers are programmable, there operating characteristics can be changed by a programmer that transmits specific electromagnetic signals through the skin. Permanent Pacemaker

Pacemaker lead in external jugular vein

Pacemaker lead tunneled subcutaneously between pacemaker and external jugular vein

Generator placed beneath skin in pectoral region

Tip of wire (electrode) lodged in apex of right ventricle

Biventricular Pacemaker A biventricular pacemaker uses three leads: one to pace the right atrium, one to pace the right ventricle, and one to pace the left ventricle. The left ventricular lead is placed in the coronary sinus. Both ventricles are paced at the same time, causing them to contract simultaneously, improving cardiac output.

Subclavian vein

Generator

Right atrial lead

metabolic demand). R = Rate modulated O = None Fifth Letter

Right atrium

Left ventricular lead (in coronary sinus)

The fifth letter designates the location of multisite pacing. V = Ventricle A = Atrium

Left ventricle

Right ventricular lead

Right ventricle

D = Dual O = None