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Question 1. Which structure directly separates the membranous septum from the tricuspid valve annulus? A) Interventricular membranous septum B) Aortic root C) Fibrous trigone D) Right atrial appendage Answer: C Explanation: The fibrous trigone links the membranous septum to the tricuspid annulus, forming a non‑muscular bridge that is critical for His bundle positioning. Question 2. The “penetrating” portion of the His bundle is best described as: A) The segment that runs within the membranous septum before emerging onto the right side of the interventricular septum B) The distal fibers that branch into the left bundle branch C) The portion that lies within the right ventricular outflow tract D) The atrial insertion of the AV node Answer: A Explanation: The penetrating His bundle travels within the membranous septum before it exits onto the right side of the muscular septum. Question 3. In left bundle branch anatomy, the anterior fascicle primarily supplies which ventricular region? A) Inferior wall of the left ventricle B) Anterolateral wall of the left ventricle C) Posterior septum D) Apex of the right ventricle
Answer: B Explanation: The left anterior fascicle distributes activation to the anterolateral LV wall, while the posterior fascicle supplies the inferior‑posterior region. Question 4. Which electrophysiological advantage does the Purkinje system provide over direct myocardial pacing? A) Shorter QRS duration and preserved ventricular synchrony B) Higher capture thresholds C) Greater risk of tachyarrhythmias D) Delayed activation of the left ventricle Answer: A Explanation: Purkinje fibers conduct rapidly, producing narrow QRS complexes and avoiding pacing‑induced dyssynchrony. Question 5. Pacing‑induced cardiomyopathy (PICM) is most closely associated with which pacing strategy? A) His‑bundle pacing B) Right ventricular apical pacing C) Left bundle branch area pacing D) Biventricular pacing with optimal AV delay Answer: B Explanation: Chronic RV apical pacing creates electrical dyssynchrony, predisposing to PICM. Question 6. Which patient group is most likely to benefit from CSP as a first‑line therapy rather than conventional CRT? A) Patients with preserved LVEF and sinus node dysfunction only
Question 9. Which sheath design is most appropriate for achieving a perpendicular approach to the interventricular septum during HBP? A) Fixed‑curve C315 HIS sheath B) Straight 8‑Fr sheath C) Deflectable 7‑Fr coronary sinus sheath D) Open‑tip femoral sheath Answer: A Explanation: The C315 HIS has a pre‑shaped curve that aligns the lead tip perpendicularly to the septal surface, facilitating stable His capture. Question 10. Lumenless leads (LLL) used in CSP differ from stylet‑driven leads (SDL) primarily in: A) Ability to deliver higher energy pulses B) Presence of an internal lumen for a guidewire, making them more flexible and thin‑walled C) Requirement for larger delivery sheaths D) Compatibility only with defibrillator devices Answer: B Explanation: LLLs have a hollow core that permits a thin, flexible lead without a stylet, improving maneuverability within the septum. Question 11. During His‑bundle mapping, the presence of a sharp, high‑frequency deflection preceding the ventricular electrogram on a unipolar recording indicates: A) Far‑field ventricular capture B) His potential C) Atrial far‑field signal
D) Noise artifact Answer: B Explanation: The His potential appears as a discrete high‑frequency signal just before ventricular activation, confirming proximity to the His bundle. Question 12. The “9‑o’clock” position in an LAO view for LBBAP refers to: A) The location of the lead tip at the inferior septum near the apex B) The orientation of the sheath at 9 o’clock on a clock‑face diagram, indicating posterior septal placement C) The angle of the fluoroscopic C‑arm to visualize the right ventricular outflow tract D) The position of the lead tip at the mid‑septal region near the left bundle branch Answer: D Explanation: In the LAO projection, the 9‑o’clock position corresponds to the mid‑septal area where the left bundle branch runs, guiding optimal lead placement. Question 13. When screwing a lead into the septum for LBBAP, an abrupt rise in torque resistance typically signifies: A) Successful engagement of the left bundle fibers B) Perforation of the septum into the left ventricle C) Contact with the trabecular muscle of the RV free wall D) Lead entanglement with the tricuspid chordae Answer: A Explanation: Increased torque resistance indicates the helix is embedding into dense septal tissue, often correlating with capture of the left bundle. Question 14. Selective His‑bundle pacing is characterized on the surface ECG by:
Explanation: The RBBB pattern reflects early left‑sided activation with delayed right‑sided depolarization, typical of successful LBB capture. Question 17. Recording a discrete left‑bundle potential during mapping is most useful for: A) Confirming lead placement within the coronary sinus B) Distinguishing between selective and non‑selective LBB capture C) Identifying the exact site for lead fixation to maximize capture probability D) Determining the need for a defibrillation coil Answer: C Explanation: The left‑bundle potential marks the anatomical location of the left bundle, guiding precise lead implantation. Question 18. When decreasing output during a transition study, the QRS morphology that changes from narrow to wider indicates: A) Loss of left‑bundle capture and emergence of myocardial capture only B.1) Progressive myocardial capture with decreasing capture thresholds C) Development of right‑bundle‑branch block D) Device malfunction Answer: A Explanation: Lowering output may drop below the threshold for left‑bundle capture, leaving only myocardial capture, which widens the QRS. Question 19. The ventricular‑to‑R‑wave peak time (V6‑RWPT) measured during LBBAP should be ≤: A) 120 ms B) 150 ms
C) 180 ms D) 200 ms Answer: B Explanation: A V6‑RWPT ≤ 150 ms suggests rapid LV activation through the left bundle, confirming physiologic pacing. Question 20. “Stim‑to‑LV activation time” is calculated by measuring the interval from the pacing spike to the earliest LV electrogram on which lead? A) Lead I B) Lead aVL C) Lead V5/V D) Lead II Answer: C Explanation: Leads V5 and V6 record lateral LV activation; the shortest interval reflects true LV capture timing. Question 21. Higher chronic thresholds observed with His‑bundle pacing are primarily due to: A) The thin, insulated nature of the His bundle requiring more current density for capture B) The use of larger lead diameters C) Inadequate device programming D) Frequent lead dislodgement Answer: A Explanation: The His bundle’s small cross‑section and surrounding fibrous tissue increase the energy needed for reliable capture.
Explanation: Septal micro‑perforation often manifests as a subtle impedance rise and reduced sensing due to exposure of the helix to the LV cavity. Question 25. To extend battery longevity in a CSP device, the most effective programming adjustment is: A) Increasing pulse width to 1.0 ms B) Reducing output voltage to just above the capture threshold C) Switching to a dual‑chamber mode with frequent atrial pacing D) Setting a higher rate response threshold Answer: B Explanation: Operating the device at the lowest voltage that reliably captures reduces energy consumption and prolongs battery life. Question 26. The BLOCK‑HF trial primarily demonstrated that: A) Conventional RV pacing is superior to His‑bundle pacing in patients with LVEF < 35% B) His‑bundle pacing reduces the composite endpoint of death, heart‑failure hospitalization, and need for upgrade compared with RV pacing in patients with high pacing burden C) Biventricular pacing is ineffective in patients with AV block D) LBBAP is associated with higher infection rates than HBP Answer: B Explanation: BLOCK‑HF showed that physiologic HBP significantly lowered adverse outcomes versus standard RV pacing in a high‑burden population. Question 27. In the HOT‑CRT study, the primary benefit of LBBAP over conventional CRT was: A) Shorter procedural time B) Lower fluoroscopy dose
C) Greater improvement in LVEF at 6 months D) Reduced need for anticoagulation Answer: C Explanation: HOT‑CRT demonstrated that LBBAP produced a larger increase in LVEF compared with standard biventricular pacing. Question 28. According to current ESC guidelines, CSP is recommended as a first‑line pacing strategy in patients with: A) Permanent atrial fibrillation and normal AV conduction B) AV block with anticipated ventricular pacing >40% and a narrow QRS at baseline C) Chronic RV apical pacing already in place for >5 years D) Isolated left bundle branch block without heart failure Answer: B Explanation: ESC guidelines endorse CSP for patients likely to need high ventricular pacing burden to prevent dyssynchrony. Question 29. Which echocardiographic parameter most directly reflects improvement after successful CSP implantation? A) Decrease in left atrial volume index B) Increase in mitral inflow E/A ratio C) Rise in left ventricular ejection fraction (LVEF) D) Reduction in inferior vena cava diameter Answer: C Explanation: LVEF improvement is the primary marker of reverse remodeling after physiologic pacing.
Answer: B Explanation: A depth of 3–5 mm usually reaches the sub‑endocardial tissue where the left bundle fibers lie, ensuring capture without perforation. Question 33. Which of the following is NOT a typical sign of lead dislodgement in CSP? A) Sudden rise in capture threshold B) Loss of His‑bundle electrogram on interrogation C) Persistent low‑voltage sensing on the atrial channel D) Change in fluoroscopic lead position on chest X‑ray Answer: C Explanation: Low atrial sensing is unrelated to ventricular lead dislodgement; the other options directly reflect lead movement. Question 34. In programming CSP devices, the “AV delay” is most critical for which of the following reasons? A) To synchronize atrial and ventricular pacing, preserving atrial contribution to ventricular filling B) To increase battery consumption C) To avoid oversensing of far‑field ventricular signals D) To reduce the incidence of lead‑related infection Answer: A Explanation: Proper AV delay ensures atrial contraction precedes ventricular activation, optimizing hemodynamics. Question 35. Which pacing output parameter is most directly linked to battery drain in a CSP device? A) Pulse width
B) Pacing mode (DDD vs VVI) C) Sensing threshold D) Lead impedance Answer: A Explanation: Longer pulse widths consume more energy per pulse, significantly affecting battery longevity. Question 36. During a CSP implantation, a “far‑field R‑wave” detected on the His channel is best managed by: A) Increasing the sensitivity setting of the His lead B) Re‑positioning the lead more distal to the His bundle C) Programming a higher pacing output D) Changing to a bipolar sensing configuration on the His channel Answer: D Explanation: Bipolar sensing reduces far‑field detection by limiting the sensing field to the immediate tip‑ring area. Question 37. Which of the following is a contraindication to attempting His‑bundle pacing? A) Prior tricuspid valve replacement with a mechanical prosthesis B) Presence of a left‑sided pacemaker lead C) Chronic atrial fibrillation D) Severe chronic kidney disease Answer: A Explanation: Mechanical tricuspid prostheses obstruct access to the septal region, making HBP technically infeasible.
Explanation: Fusion pacing occurs when paced impulses combine with native conduction, resulting in a QRS that is narrower than pure myocardial capture but wider than pure selective capture. Question 41. Which of the following best describes the effect of a shorter AV delay in a DDD‑mode CSP system? A) Increases atrial contribution to ventricular filling B) May cause atrial “sensing‑pacing” competition leading to pacemaker syndrome C) Reduces the likelihood of pacemaker‑mediated tachycardia D) Enhances ventricular pre‑excitation Answer: B Explanation: An excessively short AV delay can lead to atrial contraction against a closed AV valve, producing pacemaker syndrome. Question 42. In a patient with chronic RV apical pacing who is upgraded to CSP, the expected change in QRS duration is: A) Increase by >30 ms B) No change C) Decrease by ≥20 ms D) Variable, depending on lead position only Answer: C Explanation: Physiologic pacing (HBP or LBBAP) typically narrows the QRS by at least 20 ms compared with RV apical pacing. Question 43. Which imaging modality is most useful for confirming septal lead depth during LBBAP implantation? A) Trans‑esophageal echocardiography (TEE)
B) Intracardiac echocardiography (ICE) C) Fluoroscopy with left‑anterior‑oblique (LAO) projection D. Cardiac MRI Answer: C Explanation: LAO fluoroscopic view allows visualization of the lead tip relative to the septal wall and helps assess depth. Question 44. A patient with CSP presents with intermittent loss of capture despite stable thresholds on interrogation. The most likely cause is: A) Lead micro‑fracture B) Battery depletion C) Intermittent loss of contact due to respiratory motion of the septum D) Software glitch in the device programmer Answer: C Explanation: Septal motion can transiently alter lead‑tissue interface, causing intermittent capture loss. Question 45. Which of the following statements about the “His‑bundle to LV activation time” is true? A) It is measured from the His potential to the onset of the QRS in lead I B) Shorter intervals predict better long‑term LV function C) It is irrelevant in LBBAP validation D) It is always >150 ms in selective HBP Answer: B Explanation: A shorter His‑to‑LV activation time reflects rapid conduction through the Purkinje system, correlating with improved LV performance.
Answer: B Explanation: The His bundle traverses the membranous portion of the interventricular septum before bifurcating. Question 49. Which of the following best explains why CSP may reduce the incidence of atrial fibrillation in patients with AV block? A) It eliminates the need for anticoagulation B) By preserving atrial‑ventricular synchrony, it reduces atrial stretch and remodeling C) CSP directly suppresses atrial ectopy through pacing D) It increases AV nodal refractory period Answer: B Explanation: Maintaining AV synchrony lowers left‑atrial pressure, decreasing atrial remodeling that predisposes to AF. Question 50. During device interrogation, a sudden increase in lead impedance from 500 Ω to 900 Ω most likely indicates: A) Lead fracture B) Septal micro‑perforation with exposure to blood pool C) Battery depletion D) Programming error Answer: B Explanation: Impedance rise often reflects loss of tissue contact or micro‑perforation, altering the electrical path. Question 51. Which programming parameter is most important to prevent “cross‑talk” between the atrial and ventricular channels in a dual‑chamber CSP system?
A) AV delay B) Refractory period settings C) Sensitivity of the ventricular lead D) Rate response slope Answer: B Explanation: Properly set refractory periods prevent the ventricular channel from sensing atrial events and vice versa. Question 52. In a patient with an implanted HBP system, the appearance of a new left‑bundle‑branch‑block pattern on ECG after a lead revision suggests: A) Successful conversion to LBBAP B) Loss of His capture with only right‑bundle capture remaining C) Development of new intrinsic LBBB unrelated to pacing D) Inadequate lead fixation causing intermittent capture Answer: B Explanation: After loss of His capture, the pacing may only stimulate the right bundle, producing an LBBB morphology. Question 53. Which of the following is the most common acute complication of LBBAP implantation? A) Coronary sinus dissection B) Septal perforation into the left ventricle C) Tricuspid valve injury D) Infection of the pocket Answer: B
