NCLEX RN Practice Question 433

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PACEMAKERS

 Description:

Temporary or permanent device that provides electrical stimulation and maintains the heart rate when the client’s intrinsic pacemaker fails to provide a perfusing rhythm

Settings

• A synchronous (demand) pacemaker senses the client’s rhythm and paces only if the client’s intrinsic rate falls below the set pacemaker rate for stimulating depolarization.
• An asynchronous (fixed rate) pacemaker paces at a preset rate regardless of the client’s intrinsic rhythm and is used when the client is asystolic or profoundly bradycardic.
• Overdrive pacing suppresses the underlying rhythm in tachydysrhythmias so that the sinus node will regain control of the heart.

Spikes

• When a pacing stimulus is delivered to the heart, a spike (straight vertical line) is seen on the monitor or electrocardiogram strip.
• Spikes precede the chamber being paced; a spike preceding a P wave indicates that the atrium is paced and a spike preceding the QRS indicates that the ventricle is being paced.
• An atrial spike followed by a P wave indicates atrial depolarization and a ventricular spike followed by a QRS complex represents ventricular depolarization; this is referred to as capture.
• If the electrode is in the atrium, the spike is before the P wave; if the electrode is in the ventricle, the spike is before the QRS complex.

Temporary pacemakers

• Noninvasive transcutaneous pacing
• Noninvasive transcutaneous pacing is used as a temporary emergency measure in the profoundly bradycardic or asystolic client until invasive pacing can be initiated.
• Large electrode pads are placed on the client’s chest and back and connected to an external pulse generator.
• Wash the skin with soap and water before applying electrodes.
• It is not necessary to shave the hair or apply alcohol or tinctures to the skin.
• Place the posterior electrode between the spine and left scapula behind the heart, avoiding placement over bone