⚕️ FCPS MCPS MD IMM Paediatrics TOACS · Mock Test
ECG Interpretation · 8-Minute Station
📚 paeds.online
⏱️ TIME REMAINING
08:00
❓ Q1. Describe the ECG findings.
✅ Model Answer:
• ECG findings: Wide QRS (>0.12 sec), AV dissociation (independent P waves), capture beats (narrow QRS), fusion beats (intermediate morphology).
• VT vs SVT with aberrancy: AV dissociation and capture/fusion beats are virtually diagnostic of VT. QRS >0.14 sec, extreme axis deviation, age >8 years, and lack of response to adenosine favor VT.
• ECG findings: Wide QRS (>0.12 sec), AV dissociation (independent P waves), capture beats (narrow QRS), fusion beats (intermediate morphology).
• VT vs SVT with aberrancy: AV dissociation and capture/fusion beats are virtually diagnostic of VT. QRS >0.14 sec, extreme axis deviation, age >8 years, and lack of response to adenosine favor VT.
❓ Q2. What are the most common causes of VT in children? Classify the underlying etiologies.
✅ Model Answer:
• Structural heart disease: Repaired TOF, cardiomyopathy (DCM, HCM, ARVC), myocarditis, anomalous coronary artery, cardiac tumors.
• Channelopathies: CPVT (RYR2), LQTS, Brugada syndrome.
• Other: Metabolic (electrolytes), drug-induced, idiopathic (RVOT VT, fascicular VT).
• Structural heart disease: Repaired TOF, cardiomyopathy (DCM, HCM, ARVC), myocarditis, anomalous coronary artery, cardiac tumors.
• Channelopathies: CPVT (RYR2), LQTS, Brugada syndrome.
• Other: Metabolic (electrolytes), drug-induced, idiopathic (RVOT VT, fascicular VT).
❓ Q3. What is catecholaminergic polymorphic VT (CPVT)? How is it diagnosed and managed?
✅ Model Answer:
• CPVT: Inherited channelopathy (RYR2, autosomal dominant) causing exercise- or emotion-induced bidirectional or polymorphic VT in structurally normal hearts.
• Diagnosis: Normal resting ECG; exercise stress test provokes VT; genetic testing (RYR2, CASQ2).
• Management: Beta-blockers (nadolol) first-line; flecainide add-on; left cardiac sympathetic denervation for refractory cases; ICD for breakthrough syncope/VF; avoid competitive sports.
• CPVT: Inherited channelopathy (RYR2, autosomal dominant) causing exercise- or emotion-induced bidirectional or polymorphic VT in structurally normal hearts.
• Diagnosis: Normal resting ECG; exercise stress test provokes VT; genetic testing (RYR2, CASQ2).
• Management: Beta-blockers (nadolol) first-line; flecainide add-on; left cardiac sympathetic denervation for refractory cases; ICD for breakthrough syncope/VF; avoid competitive sports.
❓ Q4. What is arrhythmogenic right ventricular cardiomyopathy (ARVC)? What are the ECG findings and management?
✅ Model Answer:
• ARVC: Genetic cardiomyopathy (PKP2, DSP) with fibrofatty replacement of RV, causing VT.
• ECG: Epsilon wave (V1-V3), T-wave inversion V1-V3, LBBB VT.
• Management: Avoid strenuous exercise; beta-blockers; ICD for sustained VT/syncope/high-risk; catheter ablation adjunctive.
• ARVC: Genetic cardiomyopathy (PKP2, DSP) with fibrofatty replacement of RV, causing VT.
• ECG: Epsilon wave (V1-V3), T-wave inversion V1-V3, LBBB VT.
• Management: Avoid strenuous exercise; beta-blockers; ICD for sustained VT/syncope/high-risk; catheter ablation adjunctive.
❓ Q5. The patient is hemodynamically stable. What is your acute management for VT?
✅ Model Answer:
• Stable monomorphic VT: IV Amiodarone 5 mg/kg over 20-60 min (max 150 mg). Repeat once if needed.
• Alternative: Lidocaine 1 mg/kg IV or Procainamide 15 mg/kg IV.
• Torsades de Pointes (TdP): IV magnesium 25-50 mg/kg.
• If unstable: Synchronized cardioversion 0.5-1 J/kg.
• Do NOT use: Adenosine, digoxin, verapamil in VT.
• Stable monomorphic VT: IV Amiodarone 5 mg/kg over 20-60 min (max 150 mg). Repeat once if needed.
• Alternative: Lidocaine 1 mg/kg IV or Procainamide 15 mg/kg IV.
• Torsades de Pointes (TdP): IV magnesium 25-50 mg/kg.
• If unstable: Synchronized cardioversion 0.5-1 J/kg.
• Do NOT use: Adenosine, digoxin, verapamil in VT.
❓ Q6. What are the indications for ICD implantation in a child with VT?
✅ Model Answer:
• Secondary prevention: Aborted cardiac arrest survivors, sustained VT with hemodynamic compromise.
• Primary prevention: TOF (QRS >180ms, LV dysfunction, sustained VT), HCM (syncope, NSVT, massive LVH), ARVC (syncope, RV dysfunction), LQTS (QTc >550ms, syncope on beta-blocker), CPVT (breakthrough syncope on beta-blocker).
• Secondary prevention: Aborted cardiac arrest survivors, sustained VT with hemodynamic compromise.
• Primary prevention: TOF (QRS >180ms, LV dysfunction, sustained VT), HCM (syncope, NSVT, massive LVH), ARVC (syncope, RV dysfunction), LQTS (QTc >550ms, syncope on beta-blocker), CPVT (breakthrough syncope on beta-blocker).
❓ Q7. What is the role of catheter ablation in VT? When is it preferred over ICD?
✅ Model Answer:
• Idiopathic VT: RVOT VT, fascicular VT – ablation is curative.
• Scar-related VT: Repaired TOF, ARVC – reduces VT burden and ICD shocks.
• Ablation is NOT a substitute for ICD in high-risk structural heart disease patients.
• Success: >90% for idiopathic VT, 70-80% for scar-related VT.
• Idiopathic VT: RVOT VT, fascicular VT – ablation is curative.
• Scar-related VT: Repaired TOF, ARVC – reduces VT burden and ICD shocks.
• Ablation is NOT a substitute for ICD in high-risk structural heart disease patients.
• Success: >90% for idiopathic VT, 70-80% for scar-related VT.
❓ Q8. A 16-year-old with repaired tetralogy of Fallot presents with presyncope and non-sustained VT. What is the next step?
✅ Model Answer:
• Evaluation: Echo (RV function, TR), Cardiac MRI (RV volumes, scar burden), Holter, Exercise stress test, EP study.
• Risk factors: QRS >180ms, LV dysfunction, sustained VT at EPS, syncope.
• High-risk → ICD. If scar-related VT → catheter ablation. Medical therapy: amiodarone or sotalol.
• Consider pulmonary valve replacement if severe PR.
• Evaluation: Echo (RV function, TR), Cardiac MRI (RV volumes, scar burden), Holter, Exercise stress test, EP study.
• Risk factors: QRS >180ms, LV dysfunction, sustained VT at EPS, syncope.
• High-risk → ICD. If scar-related VT → catheter ablation. Medical therapy: amiodarone or sotalol.
• Consider pulmonary valve replacement if severe PR.
❓ Q9. A child on oral erythromycin develops Torsades de Pointes (TdP). What is the acute management and which drugs prolong QT?
✅ Model Answer:
• Acute management: IV magnesium 25-50 mg/kg, discontinue QT-prolonging drugs, correct K+ (>4.5), Mg2+ (>2.0). Overdrive pacing or isoproterenol if needed. Defibrillation if unstable.
• QT-prolonging drugs: Macrolides (erythromycin), fluoroquinolones, antipsychotics (haloperidol), antiarrhythmics (sotalol, quinidine), antihistamines (terfenadine), methadone.
• Acute management: IV magnesium 25-50 mg/kg, discontinue QT-prolonging drugs, correct K+ (>4.5), Mg2+ (>2.0). Overdrive pacing or isoproterenol if needed. Defibrillation if unstable.
• QT-prolonging drugs: Macrolides (erythromycin), fluoroquinolones, antipsychotics (haloperidol), antiarrhythmics (sotalol, quinidine), antihistamines (terfenadine), methadone.
❓ Q10. This child's paternal uncle died suddenly at age 32. How would you screen the family?
✅ Model Answer:
• First-degree relatives: ECG, exercise stress test, Holter, echocardiogram. Cardiac MRI if ARVC suspected.
• Genetic testing: If proband has pathogenic variant → cascade screening. If no variant → clinical screening every 1-2 years.
• Genetic counseling: Discuss 50% risk, variable penetrance, reproductive options.
• First-degree relatives: ECG, exercise stress test, Holter, echocardiogram. Cardiac MRI if ARVC suspected.
• Genetic testing: If proband has pathogenic variant → cascade screening. If no variant → clinical screening every 1-2 years.
• Genetic counseling: Discuss 50% risk, variable penetrance, reproductive options.
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💡 Examiner's note: Compare your answers with the model answers. In real TOACS, you would discuss these with the examiner.