Pacemaker Rhythm Analysis Flashcards

A pacemaker spike followed by a wide, abnormal QRS complex indicates what type of pacing?

Answer: Ventricular pacing with successful capture

A pacemaker spike immediately followed by a wide QRS complex confirms ventricular pacing with successful capture — the pacemaker stimulus has successfully depolarized the ventricular myocardium.

Pacemaker failure to capture is identified by which ECG finding?

Answer: Pacemaker spikes visible without subsequent QRS complexes

Failure to capture occurs when the pacemaker fires (spike visible) but the electrical stimulus fails to depolarize the myocardium, so no QRS complex follows the spike.

Pacemaker oversensing causes which problem?

Answer: Inappropriate inhibition of pacing pulses due to sensing signals that are not cardiac in origin

Oversensing occurs when the pacemaker incorrectly interprets non-cardiac signals (muscle potentials, electromagnetic interference) as intrinsic cardiac activity, inhibiting appropriate pacing and causing bradycardia.

The NBG (NASPE/BPEG) pacemaker code uses letters to describe pacemaker function. In a VVI pacemaker, what does the second 'V' indicate?

Answer: The ventricle is the sensed chamber

In the NBG code, the first letter indicates the paced chamber, the second letter indicates the sensed chamber. In VVI, the second V means the ventricle is the sensed chamber.

In a DDD pacemaker, what does the first 'D' represent?

Answer: Both atrium and ventricle are paced (dual chamber pacing)

In DDD mode, the first D indicates that both the atrium and ventricle can be paced (dual chamber pacing), making it the most physiologic pacemaker mode.

Pacemaker undersensing is identified by which ECG pattern?

Answer: Pacemaker spikes firing at inappropriate times during or after intrinsic cardiac beats

Undersensing means the pacemaker fails to detect intrinsic cardiac activity, causing it to fire at its programmed interval even when the heart has already depolarized spontaneously.