Pacemaker Rhythm Analysis Flashcards

What is pacemaker syndrome?

Answer: Symptoms from loss of AV synchrony in VVI pacing, causing retrograde atrial contraction against closed mitral valve

Pacemaker syndrome occurs with VVI pacing when retrograde (ventriculo-atrial) conduction causes atria to contract against closed AV valves, producing low cardiac output, hypotension, and symptoms of heart failure.

Rate response (R) in pacemaker programming allows the device to do which of the following?

Answer: Increase pacing rate in response to physical activity by detecting body movement or minute ventilation

Rate-responsive pacemakers (VVIR, DDDR) use accelerometers or minute ventilation sensors to detect activity and increase pacing rate, simulating the normal sinus node chronotropic response to exercise.

Which intervention should be attempted first for a pacemaker patient presenting with failure to capture?

Answer: Increase pacing output amplitude on the programmer or apply a magnet to evaluate threshold

The first step is to increase the pacing output (voltage or pulse width) via programming to overcome an elevated stimulation threshold, which may restore capture before considering invasive interventions.

In a patient with a permanent pacemaker, a magnet applied over the pulse generator typically causes what pacemaker behavior?

Answer: Asynchronous pacing at a fixed rate (magnet rate), ignoring sensed cardiac activity

A magnet converts the pacemaker to asynchronous (DOO or VOO) mode, delivering pacing pulses at a fixed programmed magnet rate regardless of any sensed cardiac activity, which is useful for testing capture or overriding oversensing.

Pacemaker-mediated tachycardia (PMT) can occur in dual-chamber pacemakers due to which mechanism?

Answer: Retrograde P waves are sensed by the atrial channel, triggering ventricular pacing, creating a reentrant loop

PMT occurs in DDD pacemakers when a premature ventricular beat conducts retrogradely to the atria; the resulting retrograde P wave is sensed by the atrial channel, which then triggers ventricular pacing, which again conducts retrogradely — creating a pacemaker-dependent reentrant loop.

Which lead position is used for most right ventricular apical pacing, and what ECG pattern does it produce?

Answer: Right ventricular apex, producing a left bundle branch block (LBBB) pattern with left axis deviation

Traditional RV apical pacing activates the left ventricle last (via slow myocardial spread), producing an LBBB morphology in V1 with left axis deviation — the expected ECG appearance of successful right ventricular pacing.