IBHRE EXAM QUESTIONS AND
ANSWERS 2025
The relative refractory period of the ventricular myocardium corresponds to which of the
following phases of the action potential - ANSWER3
small subendocardial structure located with the interatrial septum - ANSWERAv node
the propagation through the AV Node and HIS-Purkinje fibers. - ANSWERPR interval
- Depolarization of neighboring cells occurs as a result of intercellular connections are
called - ANSWERGap Junctions
Chemistry Used in the vast majority of ICD's today.
Optimized for pulses of high current to charge the defibrillation capacitor quickly. Known
as the "High-Rate" battery. - ANSWERLithium silver vanadium oxide (Levi)
Abnormal QT interval is - ANSWER>0.43 sec or 430 milliseconds.
• Rule of thumb: QT > than ½ the R-R interval is abnormal).
What is the most frequent mechanism in unexplained syncope: - ANSWERBrady
arrhythmias
thickened left ventricular septum and lateral wall resulting in poor cardiac output with
intrinsic ventricular conduction - ANSWERHOCM
Antiarrhythmics:
• Moderate reduction in phase 0 slope; increase APD, increase ERP - ANSWERClass
1A
Antiarrhythmics:
• Small reduction in phase 0 slope; reduce Action Potential Duration (APD's) decrease
ERP. - ANSWERClass 1B
Antiarrhythmics:
• Pronounced reduction in phase 0 slope; no effect on APD or ERP - ANSWERClass 1C
Antiarrhythmics:
• Beta Blockers block sympathetic activity; reduce rate and conduction, decreases slope
of Phase 4 in the action potential. - ANSWERClass 2
Antiarrhythmics:
, • Potassium Channel Blockers, delay repolarization (phase 3) and thereby increase
action potential duration and effective refractory period.
•proarrhythmia - ANSWERClass 3
Antiarrhythmics:
• Slow Calcium Channel Blockers decrease systemic vascular resistance and prolong
phase 2 of the action potential. - ANSWERClass 4
- May increase or decrease defibrillation thresholds.
- Variable response due to class 1 and 3 actions
- May slow VT rates - ANSWERClass 3 (Amiodarone, pacerone, cordarone)
- May decrease defibrillation thresholds.
- May slow VT rates.
- Alter cycle lengths. - ANSWERClass 2 (beta blockers)
- Slow ventricular conduction velocity and may increase DFT. - ANSWERClass 1
7) Li/cFx: Lithium poly carbon monofluoride is new for devices requiring more/less
energy? - ANSWERMore energy
1 HZ = how many bpm - ANSWER60
switch activated by a magnet causing asynchronous pacing, now a solid state magnet
detector. - ANSWERReed switch
restrics current flow to one direction - ANSWERDiode
restricts current flow. - ANSWERResistor
converts a biphasic signal to all positive or negative - ANSWERRectifier
semiconductor used for switching and amplification - ANSWERTransistor
only takes in positive feedback. - ANSWEROpen loop sensor
physiologic change is converted to a rate and the resultant rate change i.e. O2 sat and
myocardial contractility. - ANSWERClosed loop sensor
To produce bipolar thresholds equivalent to unipolar the anode must be at least how
many times larger than the cathode - ANSWER3x
Pacing lead anodes tend to run in the how many mm? - ANSWER4-20
Icd electrodes run how many mm - ANSWER2-10
ANSWERS 2025
The relative refractory period of the ventricular myocardium corresponds to which of the
following phases of the action potential - ANSWER3
small subendocardial structure located with the interatrial septum - ANSWERAv node
the propagation through the AV Node and HIS-Purkinje fibers. - ANSWERPR interval
- Depolarization of neighboring cells occurs as a result of intercellular connections are
called - ANSWERGap Junctions
Chemistry Used in the vast majority of ICD's today.
Optimized for pulses of high current to charge the defibrillation capacitor quickly. Known
as the "High-Rate" battery. - ANSWERLithium silver vanadium oxide (Levi)
Abnormal QT interval is - ANSWER>0.43 sec or 430 milliseconds.
• Rule of thumb: QT > than ½ the R-R interval is abnormal).
What is the most frequent mechanism in unexplained syncope: - ANSWERBrady
arrhythmias
thickened left ventricular septum and lateral wall resulting in poor cardiac output with
intrinsic ventricular conduction - ANSWERHOCM
Antiarrhythmics:
• Moderate reduction in phase 0 slope; increase APD, increase ERP - ANSWERClass
1A
Antiarrhythmics:
• Small reduction in phase 0 slope; reduce Action Potential Duration (APD's) decrease
ERP. - ANSWERClass 1B
Antiarrhythmics:
• Pronounced reduction in phase 0 slope; no effect on APD or ERP - ANSWERClass 1C
Antiarrhythmics:
• Beta Blockers block sympathetic activity; reduce rate and conduction, decreases slope
of Phase 4 in the action potential. - ANSWERClass 2
Antiarrhythmics:
, • Potassium Channel Blockers, delay repolarization (phase 3) and thereby increase
action potential duration and effective refractory period.
•proarrhythmia - ANSWERClass 3
Antiarrhythmics:
• Slow Calcium Channel Blockers decrease systemic vascular resistance and prolong
phase 2 of the action potential. - ANSWERClass 4
- May increase or decrease defibrillation thresholds.
- Variable response due to class 1 and 3 actions
- May slow VT rates - ANSWERClass 3 (Amiodarone, pacerone, cordarone)
- May decrease defibrillation thresholds.
- May slow VT rates.
- Alter cycle lengths. - ANSWERClass 2 (beta blockers)
- Slow ventricular conduction velocity and may increase DFT. - ANSWERClass 1
7) Li/cFx: Lithium poly carbon monofluoride is new for devices requiring more/less
energy? - ANSWERMore energy
1 HZ = how many bpm - ANSWER60
switch activated by a magnet causing asynchronous pacing, now a solid state magnet
detector. - ANSWERReed switch
restrics current flow to one direction - ANSWERDiode
restricts current flow. - ANSWERResistor
converts a biphasic signal to all positive or negative - ANSWERRectifier
semiconductor used for switching and amplification - ANSWERTransistor
only takes in positive feedback. - ANSWEROpen loop sensor
physiologic change is converted to a rate and the resultant rate change i.e. O2 sat and
myocardial contractility. - ANSWERClosed loop sensor
To produce bipolar thresholds equivalent to unipolar the anode must be at least how
many times larger than the cathode - ANSWER3x
Pacing lead anodes tend to run in the how many mm? - ANSWER4-20
Icd electrodes run how many mm - ANSWER2-10
