1
IBHRE CCDS Exam Question Bank Actual
Exam 2026/2027 | Complete Exam-Style
Questions | 100% Verified – Detailed
Rationales – Pass Guaranteed – A+ Graded
TABLE OF CONTENTS
Section 1 | Cardiac Anatomy, Electrophysiology, and Pharmacology | Q1 – Q105
Section 2 | Indications and Guidelines for Device Therapy | Q106 – Q210
Section 3 | Pacemaker and ICD Functionality | Q211 – Q315
Section 4 | Cardiac Resynchronization Therapy and Lead Management | Q316 – Q420
Section 5 | Troubleshooting, Follow-up, and Remote Monitoring | Q421 – Q525
Instructions: Choose the single best answer. Pass: 75% in 180 minutes.
══════════════════════════════════════
SECTION 1: CARDIAC ANATOMY, ELECTROPHYSIOLOGY, AND PHARMACOLOGY Q1
– Q105
══════════════════════════════════════
Question 1 of 525
A 65-year-old male with a history of ischemic cardiomyopathy is undergoing an
electrophysiology study for syncope. During the procedure, the catheter is positioned in the
region of the His bundle. The physician observes that the His potential occurs 20 ms prior to the
onset of the QRS complex on the surface ECG. Which of the following anatomic relationships
best explains this timing?
A. The His bundle is located within the right atrial appendage
B. The His bundle penetrates the central fibrous body to reach the ventricles
,2
C. The His bundle is distal to the Bundle of Kent
D. The His bundle is insulated from the atrial myocardium
Correct Answer: B
Rationale: The His bundle traverses the central fibrous body, which acts as an electrical insulator
between the atria and ventricles, allowing the His potential to be recorded before ventricular
depolarization begins. Choice A is incorrect because the right atrial appendage is anatomically
distant from the septal location where the His potential is typically recorded.
Question 2 of 525
A 72-year-old female presents with dizziness and is found to have a prolonged QT interval on
her ECG. She is currently taking multiple medications for hypertension and arrhythmias. Which
of the following mechanisms is most likely responsible for the drug-induced prolongation of the
action potential duration?
A. Inhibition of the rapid sodium channels (INa)
B. Blockade of the slow inward calcium current (ICa-L)
C. Inhibition of the rapid component of the delayed rectifier potassium current (IKr)
D. Stimulation of the sodium-potassium ATPase pump
Correct Answer: C
Rationale: Many drugs that cause QT prolongation, such as sotalol or dofetilide, work by
blocking the IKr potassium current, which delays repolarization and prolongs the action potential
duration. Choice A is incorrect because sodium channel blockade typically slows conduction
velocity (phase 0) rather than prolonging repolarization.
Question 3 of 525
,3
During an EP study, a train of stimuli is delivered at a cycle length of 600 ms, followed by a
premature extrastimulus (S2) that is decremented by 10 ms. The longest coupling interval of the
S2 that fails to capture the atrial myocardium is 280 ms. This interval is defined as which of the
following?
A. Effective refractory period
B. Relative refractory period
C. Functional refractory period
D. Action potential duration
Correct Answer: A
Rationale: The effective refractory period (ERP) is defined as the longest coupling interval of a
premature stimulus that fails to propagate and capture the tissue. Choice B is incorrect because
the relative refractory period refers to a period during which a depolarized stimulus can capture,
but requires a stronger stimulus or results in slowed conduction.
Question 4 of 525
A 58-year-old male with a history of heart failure is initiated on amiodarone for recurrent atrial
fibrillation. Three months later, he presents with fatigue and weight gain. Thyroid function tests
reveal an elevated TSH and low free T4. Which of the following is the most likely mechanism of
amiodarone-induced hypothyroidism?
A. Destruction of thyroid follicular cells via cytotoxic T-cells
B. Inhibition of 5'-deiodinase enzyme reducing conversion of T4 to T3
C. Stimulation of the pituitary gland to secrete excess TSH
D. Iodine excess leading to Wolff-Chaikoff effect
Correct Answer: D
, 4
Rationale: Amiodarone contains a high iodine load, which can inhibit thyroid hormone synthesis
(Wolff-Chaikoff effect) or trigger autoimmune thyroiditis, leading to hypothyroidism in
susceptible individuals. Choice B is incorrect because while amiodarone does inhibit T4 to T3
conversion, this typically causes an "euthyroid sick" pattern rather than true clinical
hypothyroidism with elevated TSH.
Question 5 of 525
A patient in the ICU develops wide-complex tachycardia at a rate of 190 bpm. Blood pressure is
stable at 110/70 mmHg. The physician decides to administer intravenous lidocaine. How does
lidocaine affect the cardiac action potential to terminate this arrhythmia?
A. It prolongs the action potential duration in ventricular myocytes
B. It blocks potassium channels responsible for repolarization
C. It shortens the action potential duration and decreases refractoriness
D. It increases the slope of phase 4 depolarization in pacemaker cells
Correct Answer: C
Rationale: Lidocaine is a Class Ib antiarrhythmic that binds to inactivated sodium channels,
shortening the action potential duration and refractory period, which helps extinguish re-entry
circuits in ischemic tissue. Choice A is incorrect because lidocaine shortens, rather than prolongs,
the action potential duration.
Question 6 of 525
While reviewing a fluoroscopic image during a device implant, you identify the location of the
coronary sinus os. It is located on the posterior aspect of the right atrium, just near the septal
leaflet of the tricuspid valve. Which other prominent structure serves as a crucial landmark for
the Triangle of Koch in this region?
A. The Eustachian ridge
IBHRE CCDS Exam Question Bank Actual
Exam 2026/2027 | Complete Exam-Style
Questions | 100% Verified – Detailed
Rationales – Pass Guaranteed – A+ Graded
TABLE OF CONTENTS
Section 1 | Cardiac Anatomy, Electrophysiology, and Pharmacology | Q1 – Q105
Section 2 | Indications and Guidelines for Device Therapy | Q106 – Q210
Section 3 | Pacemaker and ICD Functionality | Q211 – Q315
Section 4 | Cardiac Resynchronization Therapy and Lead Management | Q316 – Q420
Section 5 | Troubleshooting, Follow-up, and Remote Monitoring | Q421 – Q525
Instructions: Choose the single best answer. Pass: 75% in 180 minutes.
══════════════════════════════════════
SECTION 1: CARDIAC ANATOMY, ELECTROPHYSIOLOGY, AND PHARMACOLOGY Q1
– Q105
══════════════════════════════════════
Question 1 of 525
A 65-year-old male with a history of ischemic cardiomyopathy is undergoing an
electrophysiology study for syncope. During the procedure, the catheter is positioned in the
region of the His bundle. The physician observes that the His potential occurs 20 ms prior to the
onset of the QRS complex on the surface ECG. Which of the following anatomic relationships
best explains this timing?
A. The His bundle is located within the right atrial appendage
B. The His bundle penetrates the central fibrous body to reach the ventricles
,2
C. The His bundle is distal to the Bundle of Kent
D. The His bundle is insulated from the atrial myocardium
Correct Answer: B
Rationale: The His bundle traverses the central fibrous body, which acts as an electrical insulator
between the atria and ventricles, allowing the His potential to be recorded before ventricular
depolarization begins. Choice A is incorrect because the right atrial appendage is anatomically
distant from the septal location where the His potential is typically recorded.
Question 2 of 525
A 72-year-old female presents with dizziness and is found to have a prolonged QT interval on
her ECG. She is currently taking multiple medications for hypertension and arrhythmias. Which
of the following mechanisms is most likely responsible for the drug-induced prolongation of the
action potential duration?
A. Inhibition of the rapid sodium channels (INa)
B. Blockade of the slow inward calcium current (ICa-L)
C. Inhibition of the rapid component of the delayed rectifier potassium current (IKr)
D. Stimulation of the sodium-potassium ATPase pump
Correct Answer: C
Rationale: Many drugs that cause QT prolongation, such as sotalol or dofetilide, work by
blocking the IKr potassium current, which delays repolarization and prolongs the action potential
duration. Choice A is incorrect because sodium channel blockade typically slows conduction
velocity (phase 0) rather than prolonging repolarization.
Question 3 of 525
,3
During an EP study, a train of stimuli is delivered at a cycle length of 600 ms, followed by a
premature extrastimulus (S2) that is decremented by 10 ms. The longest coupling interval of the
S2 that fails to capture the atrial myocardium is 280 ms. This interval is defined as which of the
following?
A. Effective refractory period
B. Relative refractory period
C. Functional refractory period
D. Action potential duration
Correct Answer: A
Rationale: The effective refractory period (ERP) is defined as the longest coupling interval of a
premature stimulus that fails to propagate and capture the tissue. Choice B is incorrect because
the relative refractory period refers to a period during which a depolarized stimulus can capture,
but requires a stronger stimulus or results in slowed conduction.
Question 4 of 525
A 58-year-old male with a history of heart failure is initiated on amiodarone for recurrent atrial
fibrillation. Three months later, he presents with fatigue and weight gain. Thyroid function tests
reveal an elevated TSH and low free T4. Which of the following is the most likely mechanism of
amiodarone-induced hypothyroidism?
A. Destruction of thyroid follicular cells via cytotoxic T-cells
B. Inhibition of 5'-deiodinase enzyme reducing conversion of T4 to T3
C. Stimulation of the pituitary gland to secrete excess TSH
D. Iodine excess leading to Wolff-Chaikoff effect
Correct Answer: D
, 4
Rationale: Amiodarone contains a high iodine load, which can inhibit thyroid hormone synthesis
(Wolff-Chaikoff effect) or trigger autoimmune thyroiditis, leading to hypothyroidism in
susceptible individuals. Choice B is incorrect because while amiodarone does inhibit T4 to T3
conversion, this typically causes an "euthyroid sick" pattern rather than true clinical
hypothyroidism with elevated TSH.
Question 5 of 525
A patient in the ICU develops wide-complex tachycardia at a rate of 190 bpm. Blood pressure is
stable at 110/70 mmHg. The physician decides to administer intravenous lidocaine. How does
lidocaine affect the cardiac action potential to terminate this arrhythmia?
A. It prolongs the action potential duration in ventricular myocytes
B. It blocks potassium channels responsible for repolarization
C. It shortens the action potential duration and decreases refractoriness
D. It increases the slope of phase 4 depolarization in pacemaker cells
Correct Answer: C
Rationale: Lidocaine is a Class Ib antiarrhythmic that binds to inactivated sodium channels,
shortening the action potential duration and refractory period, which helps extinguish re-entry
circuits in ischemic tissue. Choice A is incorrect because lidocaine shortens, rather than prolongs,
the action potential duration.
Question 6 of 525
While reviewing a fluoroscopic image during a device implant, you identify the location of the
coronary sinus os. It is located on the posterior aspect of the right atrium, just near the septal
leaflet of the tricuspid valve. Which other prominent structure serves as a crucial landmark for
the Triangle of Koch in this region?
A. The Eustachian ridge
