1|Page
CCDS IBHRE EXAM (A)+ |ACTUAL
QUESTIONS WITH VERIFIED
SOLUTIONS 2026
Upper Limit of Vulnerability - correct-answer - the weakest shock strength at or
above which VF is not induced when the shock is delivered at any time during the
vulnerable period.
AVNRT - correct-answer - - AV node can be thought of as divided into two
conduction pathways
- premature impulse is blocked in the fast pathway
- impulse travels down the slow pathway
- impulse again reaches the fast pathway in retrograde fashion
- impulse then reenter the slow pathyway
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rule of thumb for AVNRT ablation, which pathway should you ablate? (slow vs
fast) - correct-answer - slow pathway because ablation of fast pathway will
significantly increase the risk of complete heart block
a successful ablation of slow pathway in AVNRT is indicated by: - correct-answer -
1. an accelerated junctional rhythm with 1:1 VA conduction during the burn
2. an increase in refractoriness of the anterograde AV node
3. elimination or alteration in dual AV nodal physiology
Complication of fast pathway ablation in AVNRT - correct-answer - 1. high grade
heart block
2. marked first degree heart block
3. pseudo-pacemaker syndrome caused by prolonged AV conduction times
resulting in atrial contraction during AV valve closure
4. persistence of atypical AV nodal reentry implying slow pathways as both the
antegrade and retrograde limbs of the tachycardia
,3|Page
p wave characteristics in AVNRT - correct-answer - - negative in inferior leads
- positive in V1
Resting (transmembrane) potential - correct-answer - the voltage difference
between the inside and the outside of the cell fiber
Action potential - correct-answer - 5 phases, the cellular characteristics of
depolarization and repolarization
Action potential phase 0 - correct-answer - The depolarization phase
The rapid sodium channels are stimulated to open causing the resting
transmembrane from above -90mV to about 0mV
Action potential phase 1 - correct-answer - early repolarization
, 4|Page
Action potential phase 2 - correct-answer - The plateau phase
mediated by the slow calcium channels essentially disrupts and delays the
repolarization started in phase 1 and prolonged the refractory period
Action potential phase 3 - correct-answer - the end of repolarization
Action potential phase 4 - correct-answer - the resting phase
ions leak back and forth between the membranes and cause a gradual increase in
the transmembrane potential
when the potential reaches the threshold voltage, the cell depolarizes.
This spontaneous depolarization is called automaticity
indication for single chamber ventricular pacing - correct-answer - chronic atrial
fibrillation
CCDS IBHRE EXAM (A)+ |ACTUAL
QUESTIONS WITH VERIFIED
SOLUTIONS 2026
Upper Limit of Vulnerability - correct-answer - the weakest shock strength at or
above which VF is not induced when the shock is delivered at any time during the
vulnerable period.
AVNRT - correct-answer - - AV node can be thought of as divided into two
conduction pathways
- premature impulse is blocked in the fast pathway
- impulse travels down the slow pathway
- impulse again reaches the fast pathway in retrograde fashion
- impulse then reenter the slow pathyway
,2|Page
rule of thumb for AVNRT ablation, which pathway should you ablate? (slow vs
fast) - correct-answer - slow pathway because ablation of fast pathway will
significantly increase the risk of complete heart block
a successful ablation of slow pathway in AVNRT is indicated by: - correct-answer -
1. an accelerated junctional rhythm with 1:1 VA conduction during the burn
2. an increase in refractoriness of the anterograde AV node
3. elimination or alteration in dual AV nodal physiology
Complication of fast pathway ablation in AVNRT - correct-answer - 1. high grade
heart block
2. marked first degree heart block
3. pseudo-pacemaker syndrome caused by prolonged AV conduction times
resulting in atrial contraction during AV valve closure
4. persistence of atypical AV nodal reentry implying slow pathways as both the
antegrade and retrograde limbs of the tachycardia
,3|Page
p wave characteristics in AVNRT - correct-answer - - negative in inferior leads
- positive in V1
Resting (transmembrane) potential - correct-answer - the voltage difference
between the inside and the outside of the cell fiber
Action potential - correct-answer - 5 phases, the cellular characteristics of
depolarization and repolarization
Action potential phase 0 - correct-answer - The depolarization phase
The rapid sodium channels are stimulated to open causing the resting
transmembrane from above -90mV to about 0mV
Action potential phase 1 - correct-answer - early repolarization
, 4|Page
Action potential phase 2 - correct-answer - The plateau phase
mediated by the slow calcium channels essentially disrupts and delays the
repolarization started in phase 1 and prolonged the refractory period
Action potential phase 3 - correct-answer - the end of repolarization
Action potential phase 4 - correct-answer - the resting phase
ions leak back and forth between the membranes and cause a gradual increase in
the transmembrane potential
when the potential reaches the threshold voltage, the cell depolarizes.
This spontaneous depolarization is called automaticity
indication for single chamber ventricular pacing - correct-answer - chronic atrial
fibrillation
