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Question 1. Which structure initiates the normal cardiac impulse in the heart? A) Atrioventricular (AV) node B) Bundle of His C) Purkinje fibers D) Sinoatrial (SA) node Answer: D Explanation: The SA node, located in the right atrium, is the primary pacemaker that generates spontaneous depolarizations, setting the heart’s rhythm. Question 2. In the cardiac conduction system, the pathway that conducts impulses from the AV node to the ventricular myocardium is: A) His-Purkinje network B) Atrial internodal tract C) Bundle of His D) Sinoatrial node Answer: C Explanation: The Bundle of His carries impulses from the AV node down the interventricular septum before dividing into the right and left bundle branches. Question 3. Which of the following best describes the sequence of ventricular depolarization on a surface ECG? A) Septal depolarization → lateral wall → apex B) Apex → base → septum C) Base → apex → lateral wall D) Septal → apex → base Answer: D Explanation: Ventricular depolarization spreads from the septum to the apex and then to the base, producing the characteristic QRS morphology. Question 4. A patient with sinus node dysfunction (SND) is most likely to present with:
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A) Persistent atrial tachycardia B) Sinus pauses >3 seconds C) First-degree AV block D) Ventricular premature beats Answer: B Explanation: SND is characterized by inappropriate sinus pauses or bradycardia, often exceeding 3 seconds, leading to symptomatic dizziness or syncope. Question 5. According to ACC/AHA/HRS guidelines, a second-degree AV block that is Mobitz type II is classified as: A) A benign finding that requires no therapy B) An indication for permanent pacing C) A reversible conduction delay that resolves with atropine D) Equivalent to first-degree block in severity Answer: B Explanation: Mobitz type II block involves intermittent failure of conduction without PR prolongation and warrants permanent pacing due to risk of progression to complete block. Question 6. Ohm’s law in pacing circuits is expressed as V = I × R. If a lead impedance is 600 Ω and the device delivers a 3.6 V pulse, the current delivered is: A) 0.006 mA B) 0.006 A C) 6 mA D) 0.6 mA Answer: B Explanation: Current I = V / R = 3.6 V / 600 Ω = 0.006 A (6 mA). Question 7. The strength-duration curve demonstrates that a lower pacing amplitude can be used if the pulse width is:
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B) On opposite ends of the lead body C) Within the generator housing D) On the tip and a ring electrode respectively Answer: D Explanation: Bipolar leads use a tip electrode as the cathode and a proximal ring electrode as the anode, creating a localized pacing circuit. Question 11. The device sensitivity setting is expressed in millivolts (mV). A lower sensitivity number means the device will: A) Detect larger signals only B) Detect smaller signals, increasing oversensing risk C) Increase pacing output voltage D) Reduce battery consumption Answer: B Explanation: Sensitivity is the minimum amplitude that the device can sense; a lower number makes the device more sensitive to low-amplitude signals, raising oversensing potential. Question 12. Oversensing of T-waves can lead to which of the following device behaviors? A) Inappropriate inhibition of pacing B) Increased capture threshold C) Automatic mode switch to VOO D) Reduction of battery voltage Answer: A Explanation: When T-waves are sensed as intrinsic events, the device may incorrectly withhold pacing, causing bradycardia. Question 13. Undersensing of intrinsic R-waves is most likely to cause: A) Inappropriate pacing inhibition
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B) Pacing at a higher rate than programmed C) Unnecessary ventricular pacing D) Mode switch to AAI Answer: C Explanation: Failure to detect intrinsic ventricular activity leads the device to deliver pacing pulses unnecessarily, increasing ventricular pacing burden. Question 14. A lead impedance reading of 200 Ω is concerning for: A) Lead fracture B) Insulation breach with short circuit C) Normal chronic lead impedance D) Generator malfunction Answer: B Explanation: Low impedance (< 200 Ω) suggests a short circuit, often due to insulation breach or conductor contact, whereas high impedance (> 2000 Ω) indicates fracture. Question 15. High lead impedance (> 2000 Ω) most commonly indicates: A) Battery depletion B) Lead fracture or disconnection C) Acute lead placement D) Normal variation in pediatric patients Answer: B Explanation: Elevated impedance reflects increased resistance, typically caused by a lead fracture or open circuit. Question 16. In the NBG code “DDD,” the first “D” indicates: A) Dual-chamber pacing mode B) Demand (sensing) pacing in the atrium C) Dual-sensing in both chambers
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Answer: B Explanation: VRP is the interval after a ventricular event during which the device will not sense another ventricular signal, preventing double counting. Question 20. The AV delay in a dual-chamber pacemaker is typically longer for a sensed atrial event than for a paced atrial event because: A) Sensed events require more processing time B) Intrinsic conduction time must be allowed before ventricular pacing C) Paced atrial events produce higher amplitudes D) To conserve battery life Answer: B Explanation: When the atrium is sensed, the device allows the patient’s intrinsic AV conduction to occur before delivering a ventricular pulse, thus using a longer AV delay. Question 21. Upper Tracking Rate (UTR) differs from Upper Pacing Rate (UPR) in that UTR refers to: A) The maximum rate at which the device will track atrial events and pace the ventricle B) The maximum ventricular pacing rate irrespective of atrial activity C) The rate at which the device switches to VOO mode D) The rate limit for sensor-driven activity pacing Answer: A Explanation: UTR is the highest rate at which atrial events are tracked and followed by ventricular pacing; UPR is the absolute maximum ventricular pacing frequency. Question 22. The Total Atrial Refractory Period (TARP) primarily influences: A) The detection of premature ventricular contractions B) The 2:1 block point during rapid atrial rates C) The ventricular safety pacing window D) The sensor-driven rate response slope
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Answer: B Explanation: TARP determines how many atrial events can be sensed before the device reaches its 2:1 block, influencing the upper rate behavior. Question 23. Medtronic’s Managed Ventricular Pacing (MVP) algorithm primarily aims to: A) Increase ventricular pacing for patients with AV block B) Minimize unnecessary right-ventricular pacing by operating in AAI(R) mode when possible C) Automatically switch to VVI mode during atrial fibrillation D) Provide rate-responsive pacing based on accelerometer data Answer: B Explanation: MVP allows the device to pace in AAI(R) as long as AV conduction is intact, reducing RV pacing burden and preserving ventricular function. Question 24. Mode switching in Medtronic devices is triggered by: A) Detection of high-rate ventricular tachycardia B) Persistent atrial tachyarrhythmia (AF/AT) exceeding the programmed rate threshold C) Low battery voltage D) Loss of lead capture Answer: B Explanation: When the device senses rapid atrial activity exceeding a predefined rate, it switches to a non-tracking mode (e.g., DDI) to prevent ventricular tracking of atrial fibrillation. Question 25. The Search AV+ feature automatically adjusts the AV delay to: A) Maximize ventricular pacing output B) Promote intrinsic AV conduction by shortening the AV interval after a non-capture episode C) Prevent pacemaker-mediated tachycardia
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C) The maximum pacing output during exercise D) The battery voltage at which the device alerts the patient Answer: B Explanation: Activity Threshold sets the motion (acceleration) level that must be exceeded before the rate-responsive algorithm increases pacing rate. Question 29. The “Slope” setting in an activity-based rate response algorithm controls: A) The maximum heart rate achievable during exercise B) The steepness of the heart-rate increase relative to activity level C) The duration of the refractory period after a paced beat D) The voltage output during capture testing Answer: B Explanation: Slope defines how aggressively the pacing rate rises as activity increases; a higher slope yields a steeper rate increase. Question 30. During exercise, a patient with a Medtronic pacemaker experiences a 2:1 AV block at 120 bpm. This is most likely due to: A) Exhaustion of battery power B) The device’s upper tracking rate being reached C) Intrinsic AV nodal disease limiting conduction at high atrial rates D) Oversensing of myopotentials causing premature inhibition Answer: C Explanation: Intrinsic AV nodal disease can cause a physiological 2:1 block when atrial rates exceed the AV node’s conduction capacity, independent of device settings. Question 31. Pacemaker-mediated tachycardia (PMT) is best treated by: A) Increasing the lower rate limit B) Extending the post-ventricular atrial refractory period (PVARP)
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C) Decreasing the ventricular output voltage D) Switching to VOO mode permanently Answer: B Explanation: Extending PVARP prevents retrograde P-waves from being sensed and thus breaks the re-entrant loop that sustains PMT. Question 32. The Elective Replacement Indicator (ERI) typically appears when the battery voltage falls to approximately: A) 2.8 V B) 2.5 V C) 2.6 V D) 3.0 V Answer: C Explanation: For most Medtronic devices, ERI is triggered when the battery voltage reaches about 2.6 V, signaling the need for replacement planning. Question 33. When a magnet is placed over a Medtronic pacemaker operating in a non-ERI state, the device will generally: A) Switch to VOO mode at 85 bpm B) Disable all pacing output C) Enter asynchronous mode at 65 bpm D) Reset the lower rate limit to 70 bpm Answer: A Explanation: Application of a magnet typically forces Medtronic devices into an asynchronous mode (VOO) at a fixed rate of 85 bpm, useful for testing and emergent situations. Question 34. In the ERI state, a Medtronic device’s magnet response changes to: A) 85 bpm asynchronous pacing persists B) 65 bpm asynchronous pacing
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D) Battery depletion below ERI Answer: B Explanation: Hysteresis is an intentional programming feature that temporarily lowers the pacing rate after activity; it mimics malfunction but is normal behavior. Question 38. During MVP transition, the device appears to “jump” from AAI(R) to DDD(R) mode. This is most likely due to: A) Battery low voltage B) Loss of AV conduction detected by the algorithm C) Magnet application D) Programmer firmware update Answer: B Explanation: MVP switches to DDD(R) when the algorithm detects that AV conduction is not reliable, ensuring ventricular support. Question 39. Auto-PVARP is a feature that automatically adjusts the post-ventricular atrial refractory period based on: A) Battery voltage levels B) Frequency of retrograde atrial activity C) Patient’s activity level D) Lead impedance trends Answer: B Explanation: Auto-PVARP shortens or lengthens the refractory period in response to detected retrograde conduction, helping to prevent PMT. Question 40. The “Hysteresis” function in a dual-chamber pacemaker is designed to: A) Increase the lower rate limit after a pause B) Allow the heart rate to fall below the programmed lower rate limit after activity, reducing pacing burden C) Extend the AV delay during atrial tachyarrhythmias
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D) Automatically switch to VOO mode when sensing fails Answer: B Explanation: Hysteresis permits the intrinsic rate to drop below the programmed LRL after exercise, decreasing unnecessary pacing. Question 41. In a patient with a Medtronic dual-chamber pacemaker programmed to DDD mode, the device will: A) Pace both chambers regardless of intrinsic activity B) Pace the ventricle only if an atrial event is sensed C) Pace each chamber on demand, tracking intrinsic atrial activity to the ventricle D) Provide fixed-rate pacing at the programmed upper rate Answer: C Explanation: DDD is a dual-chamber, demand mode that senses atrial activity and, if needed, delivers ventricular pacing after the programmed AV delay. Question 42. The “Upper Rate Limit” (URL) in a rate-responsive pacemaker controls: A) The maximum sensor-driven rate regardless of atrial activity B) The highest rate at which the device will pace the ventricle when tracking atrial events C) The minimum pacing rate during sleep D) The refractory period after each paced beat Answer: B Explanation: URL caps the ventricular pacing rate when the device is tracking atrial events, preventing excessively rapid ventricular rates. Question 43. A lead with an impedance of 1500 Ω is considered: A) Normal for a chronic ventricular lead B) Indicative of a lead fracture C) Too low, suggesting insulation breach
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Answer: C Explanation: Auto-Capture tests capture after each paced beat (or at intervals) and modifies output to maintain a preset safety margin. Question 47. A patient with a Medtronic pacemaker experiences “ventricular capture loss” only during deep inspiration. The most likely cause is: A) Lead dislodgement B) Intermittent high-output demand due to oversensing of diaphragmatic EMG C) Battery depletion D) Programming of a too-short AV delay Answer: B Explanation: Inspiratory diaphragmatic myopotentials can be oversensed, causing inappropriate inhibition of pacing and resulting in apparent capture loss during deep breaths. Question 48. The “Rate Smoothing” algorithm is used to: A) Prevent sudden changes in pacing rate by limiting the difference between consecutive intervals B) Accelerate heart rate during exercise C) Reduce battery consumption by decreasing output voltage D) Automatically switch to VOO mode in case of atrial oversensing Answer: A Explanation: Rate smoothing limits rapid fluctuations in pacing intervals, providing a more physiologic heart-rate profile. Question 49. Which of the following best describes the “Automatic Mode Switch” (AMS) response when atrial fibrillation is detected? A) Switches from DDD to VVI at a fixed rate of 120 bpm B) Switches from DDD to DDI, preventing ventricular tracking of atrial fibrillation C) Increases the lower rate limit to 70 bpm D) Initiates a magnet response to pause pacing
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Answer: B Explanation: AMS typically changes the mode to a non-tracking mode such as DDI to avoid rapid ventricular pacing during AF. Question 50. In the context of Medtronic pacing, “Search AV+” differs from “Search AV” by: A) Extending the AV delay further after a non-capture event B) Shortening the AV delay progressively to test for intrinsic conduction more aggressively C) Disabling automatic threshold testing D) Adjusting the lower rate limit automatically Answer: B Explanation: Search AV+ reduces the AV delay incrementally after each non-capture, promoting intrinsic AV conduction faster than the standard Search AV. Question 51. The “Activity Threshold” is set too low in an elderly patient. The most likely clinical consequence is: A) Failure of the rate-responsive function to increase heart rate during activity B) Excessive pacing rate increases during minor movements, leading to unnecessary tachycardia C) Battery depletion due to constant high-output pacing D) Inability to detect atrial tachyarrhythmias Answer: B Explanation: A low activity threshold makes the device interpret trivial motions as significant activity, causing inappropriate rate elevations. Question 52. Which parameter directly influences the duration of the sensor-driven rate response during the “Recovery” phase? A) Reaction time B) Recovery time C) Upper rate limit
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D) Disable the magnet response feature Answer: B Explanation: A rapid low-impedance change suggests a short circuit, which can lead to loss of capture or device damage; immediate evaluation is required. Question 56. The “Post-ventricular atrial refractory period” (PVARP) is critical for preventing: A) Ventricular tachycardia B) Pacemaker-mediated tachycardia (PMT) C) Atrial undersensing D) Battery depletion Answer: B Explanation: Extending PVARP prevents retrograde P-waves from being sensed, thereby breaking the re-entrant circuit that causes PMT. Question 57. In a dual-chamber pacemaker, the “Dual-sensed, dual-paced” (DDD) mode will track atrial events up to the: A) Lower rate limit B) Upper tracking rate (UTR) C) Maximum sensor rate D) Fixed ventricular rate set by the programmer Answer: B Explanation: DDD tracks atrial events only up to the programmed UTR; beyond that, the device may impose a 2:1 block or other rate-limiting behavior. Question 58. Which of the following is NOT a typical cause of oversensing? A) Myopotentials from skeletal muscle B) Electromagnetic interference from diathermy C) Low lead impedance due to fracture D) T-wave sensing in ventricular channels
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Answer: C Explanation: Low impedance usually causes undersensing or short-circuit issues, not oversensing; oversensing stems from external electrical signals or high-amplitude cardiac components. Question 59. A patient with a Medtronic pacemaker programmed to “AAI(R)” experiences symptomatic bradycardia during sleep. The most appropriate programming change is: A) Switch to VVI mode B) Increase the lower rate limit C) Enable rate-adaptive pacing with an accelerometer D) Add a ventricular lead and program DDD mode Answer: D Explanation: If sinus node function is insufficient, adding ventricular support (DDD) ensures reliable ventricular pacing, especially during sleep when intrinsic rate may fall. Question 60. The “Refractory Period” following a paced atrial event is called: A) Post-atrial ventricular refractory period (PAVR) B) Atrial blanking period (ABP) C) Ventricular refractory period (VRP) D) Post-ventricular atrial refractory period (PVARP) Answer: B Explanation: The atrial blanking period prevents the device from sensing the atrial pacing artifact as an intrinsic atrial event. Question 61. In an MVP-enabled device, the term “ventricular pacing burden” refers to: A) The percentage of ventricular beats delivered by the pacemaker over a given period B) The total energy consumption of the ventricular lead
