PAPER QUESTIONS AND SOLUTIONS 2026
GRADED A+
◉ Action potential
Answer: 5 phases, the cellular characteristics of depolarization and
repolarization
◉ Action potential phase 0
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
Answer: early repolarization
◉ Action potential phase 2
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
Answer: the end of repolarization
◉ Action potential phase 4
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
Answer: chronic atrial fibrillation
◉ Increase level of ANP or BNP in a pacemaker patient may be
related to
Answer: VVI pacing or loss of atrial capture/synchrony
◉ minimal pacing rate on VDD mode
Answer: base interval in ms plus PV interval divided by 60000
◉ VDD pacing - using unipolar lead, bipolar lead(wide spacing and
narrow spacing), and orthogonal
,Answer: Unipolar - oversensing extraneous signals such as
myopotentials
Bipolar - eliminates the likelihood for myopotential oversensing, the
wide spacing has the lowest and widest signal deflection while the
narrow spacing has the highest and fastest deflection
Orthogonal - half rings located directly opposite each other on the
lead body with electrically opposite plate
◉ indication of VDD pacing
Answer: complete heart block without evidence of chronotropic
incompetence, sinus node disease, retrograde conduction, or atrial
arrhythmias
◉ Brugada syndrome
Answer: 1. right bundle branch block
2. ST elevation in V1 to V3
3. morphology of the QRS complex resembling J point elevation
4. related to sudden death
5. structurally normal heart
6. based on phase 2 of the action potential retry due to Na channel
involvement
◉ Brugada syndrome presentation
, Answer: 1. syncope and sudden death caused by fast, POLYMORPHIC
ventricular tachycardia or ventricular fibrillation
2. no warning
3. no prolongation of the QT interval during sinus rhythm
4. only in very few cases there is alternation of long-short sequences
before the polymorphic VT
5. no preceding acceleration in the heart rate as the case of
catecholamine-dependent polymorphic VT
◉ Brugada syndrome EP findings
Answer: 1. majority of the patients with normal sinus node
2. 10% with afib
3. inducibility of VF - easily induced by 1 or 2 ventricular pacing, or
3.
4. sustained VF, cause hemodynamic collapse, and requires external
DC
5. HV interval is prolonged in about half of the patients, but rarely
exceeding 70ms
◉ Drugs that are primarily eliminated by liver
Answer: - quinidine
- mexiletine
- propafenone