IBHRE - International Board of Heart Rhythm Examiners Implantable Device Functionality Questions and Answers

Question 1

A patient with a dual-chamber pacemaker programmed in DDD mode reports palpitations.
The device interrogation reveals a tachycardia with a ventricular rate locked at the upper tracking rate.
The intracardiac electrogram shows that each ventricular paced event is followed by a retrograde P-wave, which is then sensed by the atrial lead, triggering the next ventricular paced event.
What is this rhythm called?

Accepted Answer

Pacemaker-mediated tachycardia (PMT)

Answer

Ventricular safety pacing (VSP)

Answer

Mode Switch event

Answer

Sensor-indicated tachycardia

Question 2

An ICD is programmed with SVT discriminators to prevent inappropriate shocks. Which of the following findings during a high-rate episode would most strongly suggest a diagnosis of VT, causing the device to override SVT criteria and deliver therapy?

Accepted Answer

AV dissociation

Answer

A stable R-R interval

Answer

A sudden onset of the tachycardia

Answer

1:1 atrioventricular (AV) association

Question 3

A patient with a VVI pacemaker presents for follow-up. The device log shows multiple episodes of pacing inhibition despite the patient's intrinsic rate being below the programmed lower rate limit. The intracardiac electrogram shows that after each intrinsic QRS complex, a second, smaller signal is consistently sensed on the ventricular channel, which inappropriately resets the pacing timer. What is the most likely cause of this pacing inhibition?

Accepted Answer

T-wave oversensing

Answer

Myopotential oversensing

Answer

Ventricular undersensing

Answer

Crosstalk

Question 4

A modern pacemaker's ventricular automatic capture feature confirms capture after each pacing stimulus by looking for an evoked response. To avoid misinterpreting the pacing artifact's afterpotential as a captured beat, the sensing amplifier is blanked for a short period. What is this afterpotential?

Accepted Answer

A residual electrical charge at the electrode-myocardium interface following the pacing stimulus

Answer

A far-field signal from the contralateral chamber

Answer

An electromagnetic interference signal generated by the pulse generator

Answer

The intrinsic R-wave that occurs just after the pacing spike

Question 5

What is the primary purpose of the Mode Switch feature in a dual-chamber implantable device?

Accepted Answer

To prevent rapid ventricular pacing in response to a detected atrial tachyarrhythmia

Answer

To increase the pacing rate during exercise using a blended sensor

Answer

To conserve battery by switching to a VVI mode at night

Answer

To prevent pacemaker-mediated tachycardia by extending the post-ventricular atrial refractory period (PVARP)

Question 6

An EGM from a dual-chamber pacemaker shows an atrial paced (AP) event followed 110 ms later by a ventricular paced (VP) event. This AP-VP sequence is intermittent and significantly shorter than the programmed AV delay of 200 ms. This behavior is most characteristic of which device feature?

Accepted Answer

Ventricular Safety Pacing (VSP)

Answer

Rate smoothing

Answer

An adaptive AV delay algorithm

Answer

Auto-adjusting sensitivity