Lesson 12

Lesson 12: Pacemaker Part 1

• Consists of a pulse generator and pacing leads delivering electrical current to the heart.

NBG Classification

• Pacemakers are identified using a 5-letter code:

  • Position 1 = Chamber paced

  • Position 2 = Chamber sensed

  • Position 3 = Response to sensed activity

  • Position 4 = Programmability options

  • Position 5 = Ability to pace multiple sites

Common Pacing Modes

• Asynchronous: AOO, VOO, DOO

• Single-chamber: AAI, VVI

• Dual-chamber: DDD

Failure to Capture

• Occurs when stimulus fails to trigger myocardial depolarization.

Cardiac Output

• Dependent on normal heart rate and rhythm; pacemaker maintains this if the heart cannot.

Components of Pacemakers

• Leads: Atrial lead (in right atrial appendage), Ventricular lead (in right ventricle apex)

• Pulse Generator: Processes electrical signals from the heart, responds based on programming.

• Battery: Often a lithium type.

Indications for Pacemaker Insertion

• SA node disease, AV node disease, Long QT syndrome, Dilated cardiomyopathy, Hypertrophic obstructive cardiomyopathy.

EKG Morphology

• Atrial pacing: Spike precedes P wave, QRS normal.

• Ventricular pacing: Spike precedes wide QRS complex.

• AV Sequential (dual chamber): Spikes for both atrial and ventricular pacing.

Key Mnemonic: PaSeR

• Pa = Chamber Paced

• Se = Chamber Sensed

• R = Response