FCPS Paediatrics TOACS · Ventricular Tachycardia (VT)
⚡ 14-year-old with palpitations, syncope – ECG: wide QRS tachycardia, AV dissociation – Causes (TOF scar, CPVT, LQTS, ARVC, myocarditis) – Amiodarone, Cardioversion, ICD, Ablation
📚 Paeds Online – paeds.online
⚕️ OBSERVED STATION · CPSP FORMAT · 8 MINUTES · SEPARATE TABS · CLINICAL SCENARIO
📖 Problem-oriented Clinical Scenario – Ventricular Tachycardia
👶🏻 Clinical Scenario (read aloud – 2 min):
A 14-year-old boy is brought to the emergency department after an episode of sudden loss of consciousness while playing basketball. He reports that he felt his heart "pounding" and became dizzy before collapsing. He was unresponsive for approximately 1 minute and then spontaneously recovered. He is now alert but complains of mild chest discomfort and palpitations. He has had two similar episodes in the past 6 months, both during exercise, but did not seek medical attention. There is no history of fever, cough, or drug use. His paternal uncle had a sudden death at age 32 while jogging; autopsy was not performed.
Examination: Vital signs: HR 180 bpm (regular), BP 105/70 mm Hg, RR 22/min, SpO2 96% on room air. Cardiovascular examination reveals a regular, rapid heart rate with no murmurs. There is no hepatomegaly or peripheral edema. Neurological examination is normal.
ECG (obtained in ED):
Task for the candidate: You are the pediatric cardiologist. Evaluate this child, interpret the ECG, differentiate VT from SVT with aberrancy, discuss the causes of VT in children (structural heart disease: repaired TOF, cardiomyopathy, ARVC; channelopathies: CPVT, LQTS; myocarditis; metabolic), formulate an acute management plan (amiodarone, cardioversion if unstable), and provide counseling about long-term management (ICD, ablation, beta-blockers, lifestyle modifications).
A 14-year-old boy is brought to the emergency department after an episode of sudden loss of consciousness while playing basketball. He reports that he felt his heart "pounding" and became dizzy before collapsing. He was unresponsive for approximately 1 minute and then spontaneously recovered. He is now alert but complains of mild chest discomfort and palpitations. He has had two similar episodes in the past 6 months, both during exercise, but did not seek medical attention. There is no history of fever, cough, or drug use. His paternal uncle had a sudden death at age 32 while jogging; autopsy was not performed.
Examination: Vital signs: HR 180 bpm (regular), BP 105/70 mm Hg, RR 22/min, SpO2 96% on room air. Cardiovascular examination reveals a regular, rapid heart rate with no murmurs. There is no hepatomegaly or peripheral edema. Neurological examination is normal.
ECG (obtained in ED):
Figure: ECG shows wide QRS tachycardia (rate 180 bpm, QRS 0.14 sec) with left bundle branch block (LBBB) morphology, AV dissociation, and occasional fusion/capture beats.
💡 Examiner instruction (interactive): This is a case of Ventricular Tachycardia (VT) – a potentially fatal arrhythmia originating from the ventricles. The candidate must recognize the ECG features of VT (wide QRS >0.12 sec, AV dissociation, capture/fusion beats), differentiate it from SVT with aberrancy, identify underlying causes (post-surgical TOF scar, CPVT, LQTS, ARVC, myocarditis, cardiomyopathy), and understand acute management (stable: amiodarone 5 mg/kg IV; unstable: synchronized cardioversion 0.5-1 J/kg). Long-term management includes ICD for high-risk patients, catheter ablation for scar-related VT, and beta-blockers for channelopathies (CPVT, LQTS). Family screening and genetic testing are essential.
🔍 Examiner Questions (interactive) – Click to reveal model answers
❓ Q1 (Examiner): “Describe the ECG findings in this child. What are the key features that distinguish VT from SVT with aberrancy?”
✅ Candidate's answer:
• ECG findings in VT:
- Wide QRS complex (>0.09 sec in children, >0.12 sec in adolescents) – this is a hallmark of VT.
- AV dissociation – independent P waves (atrial rate slower than ventricular rate).
- Capture beats – normal QRS complexes (narrow) that occur when a supraventricular impulse briefly captures the ventricles.
- Fusion beats – QRS complexes that are intermediate between wide (VT) and narrow (capture) – due to fusion of a ventricular and supraventricular impulse.
- LBBB or RBBB morphology – depending on the site of origin in the ventricle.
• Features that distinguish VT from SVT with aberrancy:
- AV dissociation: Strongly suggests VT (unless there is retrograde VA conduction).
- Capture/fusion beats: Virtually diagnostic of VT.
- QRS >0.14 sec – more likely VT (but not absolute).
- Extreme axis deviation – favors VT.
- Age >8 years – VT more common with structural heart disease.
- Response to adenosine: Adenosine terminates SVT but does not affect VT (may unmask atrial activity).
- ECG in sinus rhythm: Look for delta wave (WPW), QRS morphology, or other clues.
• ECG findings in VT:
- Wide QRS complex (>0.09 sec in children, >0.12 sec in adolescents) – this is a hallmark of VT.
- AV dissociation – independent P waves (atrial rate slower than ventricular rate).
- Capture beats – normal QRS complexes (narrow) that occur when a supraventricular impulse briefly captures the ventricles.
- Fusion beats – QRS complexes that are intermediate between wide (VT) and narrow (capture) – due to fusion of a ventricular and supraventricular impulse.
- LBBB or RBBB morphology – depending on the site of origin in the ventricle.
• Features that distinguish VT from SVT with aberrancy:
- AV dissociation: Strongly suggests VT (unless there is retrograde VA conduction).
- Capture/fusion beats: Virtually diagnostic of VT.
- QRS >0.14 sec – more likely VT (but not absolute).
- Extreme axis deviation – favors VT.
- Age >8 years – VT more common with structural heart disease.
- Response to adenosine: Adenosine terminates SVT but does not affect VT (may unmask atrial activity).
- ECG in sinus rhythm: Look for delta wave (WPW), QRS morphology, or other clues.
❓ Q2 (Examiner): “What are the most common causes of VT in children? How would you classify the underlying etiologies?”
✅ Candidate's answer:
• Structural heart disease (most common in older children):
- Repaired congenital heart disease: Tetralogy of Fallot (scars from VSD patch, right ventriculotomy), VSD repair, arterial switch, Fontan, Mustard/Senning.
- Cardiomyopathy: Dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy (ARVC).
- Myocarditis: Viral (Coxsackie, Parvovirus B19), autoimmune, Lyme disease.
- Anomalous coronary artery: Anomalous left coronary artery from pulmonary artery (ALCAPA) – with ischemic VT.
- Cardiac tumors: Rhabdomyoma (tuberous sclerosis), fibroma.
• Channelopathies (no structural heart disease):
- Long QT syndrome (LQTS): LQT1, LQT2, LQT3 – Torsades de Pointes.
- Catecholaminergic polymorphic VT (CPVT): RYR2 mutation, stress-induced bidirectional VT.
- Brugada syndrome: SCN5A mutation, coved ST elevation in V1-V2.
- Short QT syndrome.
• Other causes:
- Metabolic: Electrolyte disturbances (K+, Mg2+, Ca2+), acidosis, mitochondrial disorders.
- Drug-induced: Proarrhythmic drugs (class I, III antiarrhythmics, QT-prolonging drugs).
- Idiopathic: RV outflow tract VT (benign, monomorphic), LV fascicular VT (verapamil-sensitive).
• Approach: Echocardiogram (structural disease), ECG (QT, Brugada), exercise test (CPVT, LQT1), cardiac MRI (scar, inflammation, ARVC), genetic testing.
• Structural heart disease (most common in older children):
- Repaired congenital heart disease: Tetralogy of Fallot (scars from VSD patch, right ventriculotomy), VSD repair, arterial switch, Fontan, Mustard/Senning.
- Cardiomyopathy: Dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy (ARVC).
- Myocarditis: Viral (Coxsackie, Parvovirus B19), autoimmune, Lyme disease.
- Anomalous coronary artery: Anomalous left coronary artery from pulmonary artery (ALCAPA) – with ischemic VT.
- Cardiac tumors: Rhabdomyoma (tuberous sclerosis), fibroma.
• Channelopathies (no structural heart disease):
- Long QT syndrome (LQTS): LQT1, LQT2, LQT3 – Torsades de Pointes.
- Catecholaminergic polymorphic VT (CPVT): RYR2 mutation, stress-induced bidirectional VT.
- Brugada syndrome: SCN5A mutation, coved ST elevation in V1-V2.
- Short QT syndrome.
• Other causes:
- Metabolic: Electrolyte disturbances (K+, Mg2+, Ca2+), acidosis, mitochondrial disorders.
- Drug-induced: Proarrhythmic drugs (class I, III antiarrhythmics, QT-prolonging drugs).
- Idiopathic: RV outflow tract VT (benign, monomorphic), LV fascicular VT (verapamil-sensitive).
• Approach: Echocardiogram (structural disease), ECG (QT, Brugada), exercise test (CPVT, LQT1), cardiac MRI (scar, inflammation, ARVC), genetic testing.
❓ Q3 (Examiner): “What is catecholaminergic polymorphic VT (CPVT)? How is it diagnosed and managed?”
✅ Candidate's answer:
• CPVT is a rare inherited channelopathy characterized by exercise- or emotion-induced bidirectional or polymorphic VT in patients with a structurally normal heart.
• Genetics: Autosomal dominant (RYR2, ~60%) or autosomal recessive (CASQ2).
• Diagnosis:
- Resting ECG is normal.
- Exercise stress test – provokes bidirectional VT or polymorphic VT during exercise.
- Holter monitor – may show frequent PVCs or VT during activity.
- Genetic testing – RYR2, CASQ2.
• Management:
- Beta-blockers (nadolol, propranolol) – first-line therapy. Nadolol (1-2 mg/kg/day) is preferred due to once-daily dosing.
- Flecainide – add-on therapy if breakthrough arrhythmias on beta-blockers.
- Left cardiac sympathetic denervation (LCSD) – for refractory cases.
- ICD – indicated for patients with recurrent syncope or VF arrest despite optimal medical therapy.
- Avoid competitive sports – beta-blockers reduce but do not eliminate risk.
- Family screening – first-degree relatives require ECG, exercise test, and genetic testing.
• CPVT is a rare inherited channelopathy characterized by exercise- or emotion-induced bidirectional or polymorphic VT in patients with a structurally normal heart.
• Genetics: Autosomal dominant (RYR2, ~60%) or autosomal recessive (CASQ2).
• Diagnosis:
- Resting ECG is normal.
- Exercise stress test – provokes bidirectional VT or polymorphic VT during exercise.
- Holter monitor – may show frequent PVCs or VT during activity.
- Genetic testing – RYR2, CASQ2.
• Management:
- Beta-blockers (nadolol, propranolol) – first-line therapy. Nadolol (1-2 mg/kg/day) is preferred due to once-daily dosing.
- Flecainide – add-on therapy if breakthrough arrhythmias on beta-blockers.
- Left cardiac sympathetic denervation (LCSD) – for refractory cases.
- ICD – indicated for patients with recurrent syncope or VF arrest despite optimal medical therapy.
- Avoid competitive sports – beta-blockers reduce but do not eliminate risk.
- Family screening – first-degree relatives require ECG, exercise test, and genetic testing.
❓ Q4 (Examiner): “What is arrhythmogenic right ventricular cardiomyopathy (ARVC)? What are the ECG findings and management?”
✅ Candidate's answer:
• ARVC is a genetic cardiomyopathy characterized by progressive fibrofatty replacement of the right ventricle (and sometimes LV), predisposing to ventricular arrhythmias.
• Genetics: Autosomal dominant (PKP2, DSP, DSG2, DSC2, JUP).
• ECG findings:
- Epsilon wave – a small deflection after the QRS in V1-V3 (pathognomonic, present in 30-50%).
- T wave inversion in V1-V3 (without RBBB).
- Late potentials on signal-averaged ECG.
- VT with LBBB morphology (originating from RV).
• Diagnosis: Task Force Criteria – ECG, imaging (MRI: RV dilation, fatty infiltration), histology (endomyocardial biopsy), family history, genetics.
• Management:
- Avoid strenuous exercise – exercise accelerates disease progression.
- Beta-blockers – reduce risk of arrhythmias.
- ICD – indicated for sustained VT, syncope, or high-risk features (RVEF <35%, LV involvement).
- Catheter ablation – adjunctive for recurrent VT (but not curative).
- Heart transplant – for end-stage heart failure.
• ARVC is a genetic cardiomyopathy characterized by progressive fibrofatty replacement of the right ventricle (and sometimes LV), predisposing to ventricular arrhythmias.
• Genetics: Autosomal dominant (PKP2, DSP, DSG2, DSC2, JUP).
• ECG findings:
- Epsilon wave – a small deflection after the QRS in V1-V3 (pathognomonic, present in 30-50%).
- T wave inversion in V1-V3 (without RBBB).
- Late potentials on signal-averaged ECG.
- VT with LBBB morphology (originating from RV).
• Diagnosis: Task Force Criteria – ECG, imaging (MRI: RV dilation, fatty infiltration), histology (endomyocardial biopsy), family history, genetics.
• Management:
- Avoid strenuous exercise – exercise accelerates disease progression.
- Beta-blockers – reduce risk of arrhythmias.
- ICD – indicated for sustained VT, syncope, or high-risk features (RVEF <35%, LV involvement).
- Catheter ablation – adjunctive for recurrent VT (but not curative).
- Heart transplant – for end-stage heart failure.
❓ Q5 (Examiner): “This child is hemodynamically stable. What is your acute management for VT?”
✅ Candidate's answer:
• For stable monomorphic VT with a pulse:
1️⃣ IV Amiodarone: 5 mg/kg IV over 20-60 minutes (max 150 mg per dose). Can be repeated once. Amiodarone is the drug of choice for stable monomorphic VT.
2️⃣ IV Lidocaine: 1 mg/kg IV push (max 3 mg/kg total). Alternative for refractory VT or if amiodarone is unavailable.
3️⃣ IV Procainamide: 15 mg/kg over 30-60 minutes – useful for post-operative VT (tetralogy of Fallot).
4️⃣ Correct electrolytes: Maintain K+ > 4.0 mEq/L, Mg2+ > 2.0 mg/dL.
5️⃣ Consider sedation if cardioversion may be needed.
• If the patient becomes unstable (hypotension, poor perfusion, altered consciousness):
- Synchronized cardioversion – 0.5-1 J/kg, increase to 2 J/kg if unsuccessful.
- Pulseless VT: Defibrillation 2 J/kg → 4 J/kg → ≥4 J/kg with CPR and epinephrine.
• Important: Do not use adenosine, digoxin, verapamil, or calcium channel blockers in VT (they are ineffective and may be harmful).
• For stable monomorphic VT with a pulse:
1️⃣ IV Amiodarone: 5 mg/kg IV over 20-60 minutes (max 150 mg per dose). Can be repeated once. Amiodarone is the drug of choice for stable monomorphic VT.
2️⃣ IV Lidocaine: 1 mg/kg IV push (max 3 mg/kg total). Alternative for refractory VT or if amiodarone is unavailable.
3️⃣ IV Procainamide: 15 mg/kg over 30-60 minutes – useful for post-operative VT (tetralogy of Fallot).
4️⃣ Correct electrolytes: Maintain K+ > 4.0 mEq/L, Mg2+ > 2.0 mg/dL.
5️⃣ Consider sedation if cardioversion may be needed.
• If the patient becomes unstable (hypotension, poor perfusion, altered consciousness):
- Synchronized cardioversion – 0.5-1 J/kg, increase to 2 J/kg if unsuccessful.
- Pulseless VT: Defibrillation 2 J/kg → 4 J/kg → ≥4 J/kg with CPR and epinephrine.
• Important: Do not use adenosine, digoxin, verapamil, or calcium channel blockers in VT (they are ineffective and may be harmful).
❓ Q6 (Examiner): “What are the indications for ICD implantation in a child with VT?”
✅ Candidate's answer:
• Secondary prevention (ICD indicated in all survivors):
- Cardiac arrest survivors (aborted SCD) due to VT/VF.
- Sustained VT with hemodynamic compromise.
• Primary prevention (ICD indicated for high-risk patients):
- Repaired tetralogy of Fallot with sustained VT, LV dysfunction (EF <35%), syncope, or QRS >180 msec.
- Hypertrophic cardiomyopathy (HCM) – with syncope, NSVT, massive LVH (>30 mm), family history SCD.
- ARVC – with sustained VT, syncope, RV dysfunction, family history SCD.
- Dilated cardiomyopathy – with sustained VT, EF <35% (in adults; pediatric data limited).
- Long QT syndrome (LQTS) – cardiac arrest survivors, syncope despite beta-blockers, QTc >550 ms, Jervell and Lange-Nielsen.
- CPVT – breakthrough syncope/VF despite optimal beta-blocker therapy.
- Brugada syndrome – cardiac arrest survivors or syncope with type 1 ECG.
• ICD type: Transvenous (older children) vs subcutaneous S-ICD (no transvenous leads) for adults/older adolescents. Epicardial for small children.
• Secondary prevention (ICD indicated in all survivors):
- Cardiac arrest survivors (aborted SCD) due to VT/VF.
- Sustained VT with hemodynamic compromise.
• Primary prevention (ICD indicated for high-risk patients):
- Repaired tetralogy of Fallot with sustained VT, LV dysfunction (EF <35%), syncope, or QRS >180 msec.
- Hypertrophic cardiomyopathy (HCM) – with syncope, NSVT, massive LVH (>30 mm), family history SCD.
- ARVC – with sustained VT, syncope, RV dysfunction, family history SCD.
- Dilated cardiomyopathy – with sustained VT, EF <35% (in adults; pediatric data limited).
- Long QT syndrome (LQTS) – cardiac arrest survivors, syncope despite beta-blockers, QTc >550 ms, Jervell and Lange-Nielsen.
- CPVT – breakthrough syncope/VF despite optimal beta-blocker therapy.
- Brugada syndrome – cardiac arrest survivors or syncope with type 1 ECG.
• ICD type: Transvenous (older children) vs subcutaneous S-ICD (no transvenous leads) for adults/older adolescents. Epicardial for small children.
❓ Q7 (Examiner): “What is the role of catheter ablation in VT? When is it preferred over ICD?”
✅ Candidate's answer:
• Catheter ablation is an important adjunctive therapy for VT, especially for scar-related VT and idiopathic VT.
• Indications for ablation:
1️⃣ Idiopathic VT: RV outflow tract VT (monomorphic, benign, often exercise-induced) – ablation is curative.
2️⃣ Scar-related VT: Post-operative congenital heart disease (tetralogy of Fallot, VSD) – ablation can reduce VT burden and ICD shocks.
3️⃣ ARVC: Adjunctive to ICD to reduce recurrent VT.
4️⃣ Fascicular VT (verapamil-sensitive): Left posterior fascicular VT – ablation curative.
5️⃣ Recurrent VT despite antiarrhythmic medications.
• Ablation is NOT a substitute for ICD in patients with structural heart disease and high risk of sudden death (ICD is still indicated). Ablation reduces the frequency of ICD shocks.
• Success rate: >90% for idiopathic VT, 70-80% for scar-related VT.
• Complications: Pericardial effusion, heart block, vascular injury.
• Catheter ablation is an important adjunctive therapy for VT, especially for scar-related VT and idiopathic VT.
• Indications for ablation:
1️⃣ Idiopathic VT: RV outflow tract VT (monomorphic, benign, often exercise-induced) – ablation is curative.
2️⃣ Scar-related VT: Post-operative congenital heart disease (tetralogy of Fallot, VSD) – ablation can reduce VT burden and ICD shocks.
3️⃣ ARVC: Adjunctive to ICD to reduce recurrent VT.
4️⃣ Fascicular VT (verapamil-sensitive): Left posterior fascicular VT – ablation curative.
5️⃣ Recurrent VT despite antiarrhythmic medications.
• Ablation is NOT a substitute for ICD in patients with structural heart disease and high risk of sudden death (ICD is still indicated). Ablation reduces the frequency of ICD shocks.
• Success rate: >90% for idiopathic VT, 70-80% for scar-related VT.
• Complications: Pericardial effusion, heart block, vascular injury.
❓ Q8 (Examiner): “A 16-year-old with repaired tetralogy of Fallot presents with presyncope and non-sustained VT. What is the next step?”
✅ Candidate's answer:
• Step 1: Comprehensive evaluation:
- Echocardiogram: Assess RV size and function, TR severity, pulmonary regurgitation.
- Cardiac MRI: Quantify RV volumes, ejection fraction, and scar burden (late gadolinium enhancement – LGE).
- Holter monitor: Assess VT burden, presence of NSVT.
- Exercise stress test: Assess for exercise-induced VT.
- Electrophysiology study (EPS): Inducibility of sustained VT.
• Risk stratification for SCD in TOF:
- QRS duration >180 msec – marker of RV dysfunction.
- LV dysfunction (EF <35-40%).
- Sustained VT at EPS.
- Syncope or presyncope.
• Management:
- If high-risk (sustained VT, LV dysfunction, syncope) → ICD implantation.
- If VT is inducible and scar-related → catheter ablation to reduce VT burden.
- Medical therapy: Amiodarone or sotalol may be used to suppress VT.
- Pulmonary valve replacement (PVR) may improve RV function and reduce VT burden in some patients.
• Step 1: Comprehensive evaluation:
- Echocardiogram: Assess RV size and function, TR severity, pulmonary regurgitation.
- Cardiac MRI: Quantify RV volumes, ejection fraction, and scar burden (late gadolinium enhancement – LGE).
- Holter monitor: Assess VT burden, presence of NSVT.
- Exercise stress test: Assess for exercise-induced VT.
- Electrophysiology study (EPS): Inducibility of sustained VT.
• Risk stratification for SCD in TOF:
- QRS duration >180 msec – marker of RV dysfunction.
- LV dysfunction (EF <35-40%).
- Sustained VT at EPS.
- Syncope or presyncope.
• Management:
- If high-risk (sustained VT, LV dysfunction, syncope) → ICD implantation.
- If VT is inducible and scar-related → catheter ablation to reduce VT burden.
- Medical therapy: Amiodarone or sotalol may be used to suppress VT.
- Pulmonary valve replacement (PVR) may improve RV function and reduce VT burden in some patients.
❓ Q9 (Examiner): “A child with acute myocarditis presents with VT. What is the management?”
✅ Candidate's answer:
• Myocarditis can cause VT due to myocardial inflammation, myocardial injury, and scar formation.
• Initial management:
- Treat heart failure – diuretics, inotropes, afterload reduction.
- Antiarrhythmic therapy: Amiodarone is preferred (avoid flecainide in acute myocarditis due to risk of proarrhythmia).
- Avoid catecholamines (may worsen arrhythmias).
- IVIG or steroids – in selected cases (giant cell myocarditis, autoimmune).
- Mechanical support (ECMO) if severe heart failure/refractory VT.
• Long-term management:
- Repeat echocardiogram – monitor recovery of LV function.
- Cardiac MRI – assess for scarring (LGE) – indicates persistent risk of VT.
- If LV function recovers and no VT recurrence: Medications may be weaned.
- If persistent scar/VT: Consider ICD (if EF <35% or sustained VT).
- Avoid competitive sports until recovery is documented (usually 6-12 months).
• Myocarditis can cause VT due to myocardial inflammation, myocardial injury, and scar formation.
• Initial management:
- Treat heart failure – diuretics, inotropes, afterload reduction.
- Antiarrhythmic therapy: Amiodarone is preferred (avoid flecainide in acute myocarditis due to risk of proarrhythmia).
- Avoid catecholamines (may worsen arrhythmias).
- IVIG or steroids – in selected cases (giant cell myocarditis, autoimmune).
- Mechanical support (ECMO) if severe heart failure/refractory VT.
• Long-term management:
- Repeat echocardiogram – monitor recovery of LV function.
- Cardiac MRI – assess for scarring (LGE) – indicates persistent risk of VT.
- If LV function recovers and no VT recurrence: Medications may be weaned.
- If persistent scar/VT: Consider ICD (if EF <35% or sustained VT).
- Avoid competitive sports until recovery is documented (usually 6-12 months).
❓ Q10 (Examiner): “A child on oral erythromycin develops Torsades de Pointes (TdP). What is the acute management and which drugs prolong QT?”
✅ Candidate's answer:
• Acute management of TdP (polymorphic VT with prolonged QT):
- IV Magnesium: 25-50 mg/kg (max 2 g) IV over 1-2 minutes – first-line.
- Discontinue all QT-prolonging drugs – erythromycin, other macrolides, fluoroquinolones, antipsychotics, antiarrhythmics.
- Correct electrolytes: K+ >4.5 mEq/L, Mg2+ >2.0 mg/dL.
- Overdrive pacing or isoproterenol (0.01-0.05 mcg/kg/min) to increase heart rate.
- If unstable: Synchronized cardioversion/defibrillation.
• Common QT-prolonging drugs:
- Antibiotics: Macrolides (erythromycin, clarithromycin), fluoroquinolones (ciprofloxacin, levofloxacin).
- Antiarrhythmics: Class IA (quinidine, procainamide), Class III (sotalol, amiodarone – lower risk).
- Psychotropics: Antipsychotics (haloperidol, risperidone), tricyclic antidepressants.
- Others: Antihistamines (terfenadine, astemizole), antiemetics (ondansetron), methadone.
• Acute management of TdP (polymorphic VT with prolonged QT):
- IV Magnesium: 25-50 mg/kg (max 2 g) IV over 1-2 minutes – first-line.
- Discontinue all QT-prolonging drugs – erythromycin, other macrolides, fluoroquinolones, antipsychotics, antiarrhythmics.
- Correct electrolytes: K+ >4.5 mEq/L, Mg2+ >2.0 mg/dL.
- Overdrive pacing or isoproterenol (0.01-0.05 mcg/kg/min) to increase heart rate.
- If unstable: Synchronized cardioversion/defibrillation.
• Common QT-prolonging drugs:
- Antibiotics: Macrolides (erythromycin, clarithromycin), fluoroquinolones (ciprofloxacin, levofloxacin).
- Antiarrhythmics: Class IA (quinidine, procainamide), Class III (sotalol, amiodarone – lower risk).
- Psychotropics: Antipsychotics (haloperidol, risperidone), tricyclic antidepressants.
- Others: Antihistamines (terfenadine, astemizole), antiemetics (ondansetron), methadone.
❓ Q11 (Examiner): “This child's paternal uncle died suddenly at age 32. How would you screen the family?”
✅ Candidate's answer:
• Family screening is essential for inherited arrhythmia syndromes (LQTS, CPVT, ARVC, Brugada) and cardiomyopathy.
• First-degree relatives (parents, siblings):
- ECG – look for QT prolongation, epsilon waves, Brugada pattern, T-wave inversions.
- Exercise stress test – to unmask CPVT or LQT1.
- Holter monitoring – to detect NSVT or frequent PVCs.
- Echocardiogram – to screen for cardiomyopathy (HCM, DCM, ARVC).
- Cardiac MRI – if ARVC is suspected.
- Genetic testing – if a pathogenic variant is identified in the proband.
• Genetic testing in the proband: Panel testing for LQTS, CPVT, ARVC, Brugada, and cardiomyopathy genes. If a variant is found, cascade screening is offered to at-risk relatives.
• If no mutation found: Clinical screening (ECG, echo, exercise test) every 1-2 years for first-degree relatives.
• Genetic counseling: Discuss 50% risk for autosomal dominant conditions, variable penetrance, and reproductive options.
• Family screening is essential for inherited arrhythmia syndromes (LQTS, CPVT, ARVC, Brugada) and cardiomyopathy.
• First-degree relatives (parents, siblings):
- ECG – look for QT prolongation, epsilon waves, Brugada pattern, T-wave inversions.
- Exercise stress test – to unmask CPVT or LQT1.
- Holter monitoring – to detect NSVT or frequent PVCs.
- Echocardiogram – to screen for cardiomyopathy (HCM, DCM, ARVC).
- Cardiac MRI – if ARVC is suspected.
- Genetic testing – if a pathogenic variant is identified in the proband.
• Genetic testing in the proband: Panel testing for LQTS, CPVT, ARVC, Brugada, and cardiomyopathy genes. If a variant is found, cascade screening is offered to at-risk relatives.
• If no mutation found: Clinical screening (ECG, echo, exercise test) every 1-2 years for first-degree relatives.
• Genetic counseling: Discuss 50% risk for autosomal dominant conditions, variable penetrance, and reproductive options.
❓ Q12 (Examiner): “Can this child return to competitive sports? What are the recommendations for VT patients?”
✅ Candidate's answer:
• AHA/ACC guidelines for sports participation in VT patients:
- Sustained VT or aborted cardiac arrest: No competitive sports unless an ICD is placed and the patient is cleared by a cardiologist. Even with ICD, avoid high-intensity contact sports.
- Non-sustained VT with normal heart: May be allowed to participate in low-moderate intensity sports after cardiology evaluation.
- CPVT, LQTS, ARVC, Brugada: No competitive sports (high risk of exercise-induced arrhythmias).
- Post-ablation for idiopathic VT: May return to sports after 3-6 months if no recurrence.
• Recommendations for this child: Since he has symptomatic VT with a family history of SCD, he should not participate in competitive sports until a comprehensive evaluation (MRI, EP study, genetic testing) is completed. If an ICD is placed, he should avoid contact sports. Low-intensity recreational activities (jogging, walking) may be allowed.
• Shared decision-making: Discuss the risks and benefits with the family.
• AHA/ACC guidelines for sports participation in VT patients:
- Sustained VT or aborted cardiac arrest: No competitive sports unless an ICD is placed and the patient is cleared by a cardiologist. Even with ICD, avoid high-intensity contact sports.
- Non-sustained VT with normal heart: May be allowed to participate in low-moderate intensity sports after cardiology evaluation.
- CPVT, LQTS, ARVC, Brugada: No competitive sports (high risk of exercise-induced arrhythmias).
- Post-ablation for idiopathic VT: May return to sports after 3-6 months if no recurrence.
• Recommendations for this child: Since he has symptomatic VT with a family history of SCD, he should not participate in competitive sports until a comprehensive evaluation (MRI, EP study, genetic testing) is completed. If an ICD is placed, he should avoid contact sports. Low-intensity recreational activities (jogging, walking) may be allowed.
• Shared decision-making: Discuss the risks and benefits with the family.
❓ Q13 (Examiner): “What metabolic abnormalities can cause VT in children?”
✅ Candidate's answer:
• Electrolyte disturbances:
- Hypokalemia (K+ <3.5): Causes U waves, ST depression, prolonged QT → risk of TdP.
- Hypomagnesemia (Mg2+ <1.8): Increases risk of TdP.
- Hypocalcemia (Ca2+ <8.5): Prolongs QT.
- Hyperkalemia (K+ >5.5): Can cause peaked T waves, wide QRS → VT/VF.
- Acidosis: Can precipitate arrhythmias.
• Metabolic disorders:
- Mitochondrial disorders: Can cause cardiomyopathy and VT.
- Carnitine deficiency: Causes cardiomyopathy, VT.
- Glycogen storage diseases: Pompe, PRKAG2 (HCM + WPW + VT).
- Thyroid disorders: Hyperthyroidism can cause tachycardia and atrial arrhythmias; hypothyroidism can cause bradycardia.
• Workup: Serum electrolytes (K, Mg, Ca, Na), BUN, creatinine, glucose, thyroid function, arterial blood gas.
• Electrolyte disturbances:
- Hypokalemia (K+ <3.5): Causes U waves, ST depression, prolonged QT → risk of TdP.
- Hypomagnesemia (Mg2+ <1.8): Increases risk of TdP.
- Hypocalcemia (Ca2+ <8.5): Prolongs QT.
- Hyperkalemia (K+ >5.5): Can cause peaked T waves, wide QRS → VT/VF.
- Acidosis: Can precipitate arrhythmias.
• Metabolic disorders:
- Mitochondrial disorders: Can cause cardiomyopathy and VT.
- Carnitine deficiency: Causes cardiomyopathy, VT.
- Glycogen storage diseases: Pompe, PRKAG2 (HCM + WPW + VT).
- Thyroid disorders: Hyperthyroidism can cause tachycardia and atrial arrhythmias; hypothyroidism can cause bradycardia.
• Workup: Serum electrolytes (K, Mg, Ca, Na), BUN, creatinine, glucose, thyroid function, arterial blood gas.
❓ Q14 (Examiner): “The parents are very anxious about the risk of sudden death. How will you counsel them?”
✅ Candidate's structured answer:
• “Your child has a condition called Ventricular Tachycardia – a fast heart rhythm that starts in the lower chambers of the heart. This can cause dizziness, fainting, and in rare cases, be life-threatening.”
• “The good news is that we have excellent treatments to manage this condition. We will do a thorough evaluation to find the cause – this includes an ultrasound of the heart (echocardiogram), a detailed MRI, and possibly a special test called an EP study.”
• “If we find a specific cause, we may be able to treat it with medication (beta-blockers or amiodarone) or with a procedure called catheter ablation – which can cure the rhythm problem in some cases.”
• “Most importantly, we will assess the risk of future dangerous rhythms. If your child is at high risk, we will recommend a small device called an ICD – an internal defibrillator that can stop dangerous rhythms and save your child's life.”
• “Your child will need to avoid competitive sports until we have completed the evaluation and treatment. But he can still lead an active, fulfilling life.”
• “We will also test other family members because some of these conditions can run in families. We are here to support you every step of the way.”
• “Your child has a condition called Ventricular Tachycardia – a fast heart rhythm that starts in the lower chambers of the heart. This can cause dizziness, fainting, and in rare cases, be life-threatening.”
• “The good news is that we have excellent treatments to manage this condition. We will do a thorough evaluation to find the cause – this includes an ultrasound of the heart (echocardiogram), a detailed MRI, and possibly a special test called an EP study.”
• “If we find a specific cause, we may be able to treat it with medication (beta-blockers or amiodarone) or with a procedure called catheter ablation – which can cure the rhythm problem in some cases.”
• “Most importantly, we will assess the risk of future dangerous rhythms. If your child is at high risk, we will recommend a small device called an ICD – an internal defibrillator that can stop dangerous rhythms and save your child's life.”
• “Your child will need to avoid competitive sports until we have completed the evaluation and treatment. But he can still lead an active, fulfilling life.”
• “We will also test other family members because some of these conditions can run in families. We are here to support you every step of the way.”
🗣️ Examiner's probing / high-yield points (Ventricular Tachycardia):
• "What is the drug of choice for stable monomorphic VT?" → Amiodarone (5 mg/kg IV).
• "What are the ECG features of VT?" → Wide QRS, AV dissociation, capture/fusion beats.
• "What is the first-line treatment for Torsades de Pointes?" → IV magnesium 25-50 mg/kg.
• "What is CPVT?" → Catecholaminergic polymorphic VT (exercise-induced, normal ECG).
• "What is the most common cause of VT in children with structural heart disease?" → Repaired tetralogy of Fallot.
• "What is the indication for ICD in a child with VT?" → Cardiac arrest survivors, sustained VT with structural heart disease, high-risk channelopathy.
• "What is the role of catheter ablation in VT?" → Curative for idiopathic VT; adjunctive for scar-related VT.
• "What is the ECG hallmark of ARVC?" → Epsilon wave in V1-V3.
• "What is the genetic test for CPVT?" → RYR2 (autosomal dominant).
• "What drugs should be avoided in a patient with VT and LQTS?" → QT-prolonging drugs (macrolides, fluoroquinolones, antipsychotics, antiarrhythmics).
• "What is the drug of choice for stable monomorphic VT?" → Amiodarone (5 mg/kg IV).
• "What are the ECG features of VT?" → Wide QRS, AV dissociation, capture/fusion beats.
• "What is the first-line treatment for Torsades de Pointes?" → IV magnesium 25-50 mg/kg.
• "What is CPVT?" → Catecholaminergic polymorphic VT (exercise-induced, normal ECG).
• "What is the most common cause of VT in children with structural heart disease?" → Repaired tetralogy of Fallot.
• "What is the indication for ICD in a child with VT?" → Cardiac arrest survivors, sustained VT with structural heart disease, high-risk channelopathy.
• "What is the role of catheter ablation in VT?" → Curative for idiopathic VT; adjunctive for scar-related VT.
• "What is the ECG hallmark of ARVC?" → Epsilon wave in V1-V3.
• "What is the genetic test for CPVT?" → RYR2 (autosomal dominant).
• "What drugs should be avoided in a patient with VT and LQTS?" → QT-prolonging drugs (macrolides, fluoroquinolones, antipsychotics, antiarrhythmics).
📘 Ventricular Tachycardia – Core Revision for TOACS
⚡ Definition
≥3 consecutive ventricular beats at rate >120 bpm. Wide QRS (>0.12 sec). Sustained (>30 sec or hemodynamic compromise) vs non-sustained.
≥3 consecutive ventricular beats at rate >120 bpm. Wide QRS (>0.12 sec). Sustained (>30 sec or hemodynamic compromise) vs non-sustained.
🔍 ECG Features
Wide QRS, AV dissociation, capture/fusion beats, extreme axis deviation. LBBB (RV origin) or RBBB (LV origin) morphology.
Wide QRS, AV dissociation, capture/fusion beats, extreme axis deviation. LBBB (RV origin) or RBBB (LV origin) morphology.
🩺 Causes
Structural: repaired TOF, cardiomyopathy, ARVC, myocarditis. Channelopathies: CPVT, LQTS, Brugada. Idiopathic: RVOT VT, fascicular VT. Metabolic: K+, Mg2+, acidosis.
Structural: repaired TOF, cardiomyopathy, ARVC, myocarditis. Channelopathies: CPVT, LQTS, Brugada. Idiopathic: RVOT VT, fascicular VT. Metabolic: K+, Mg2+, acidosis.
💊 Acute Management
Unstable: cardioversion/defibrillation. Stable monomorphic: amiodarone 5 mg/kg IV. TdP: IV magnesium 25-50 mg/kg. Correct electrolytes.
Unstable: cardioversion/defibrillation. Stable monomorphic: amiodarone 5 mg/kg IV. TdP: IV magnesium 25-50 mg/kg. Correct electrolytes.
📈 Long-Term Management
Beta-blockers (CPVT, LQTS). ICD for high-risk (aborted arrest, sustained VT, structural disease). Catheter ablation for idiopathic/scar-related VT.
Beta-blockers (CPVT, LQTS). ICD for high-risk (aborted arrest, sustained VT, structural disease). Catheter ablation for idiopathic/scar-related VT.
🧬 Genetic Syndromes
CPVT (RYR2): exercise-induced, normal ECG. LQTS (KCNQ1, KCNH2, SCN5A): prolonged QT. ARVC (PKP2): epsilon wave, T-wave inversion V1-V3.
CPVT (RYR2): exercise-induced, normal ECG. LQTS (KCNQ1, KCNH2, SCN5A): prolonged QT. ARVC (PKP2): epsilon wave, T-wave inversion V1-V3.
⭐ High-yield pearls for TOACS (Ventricular Tachycardia):
• Amiodarone is first-line for stable monomorphic VT.
• AV dissociation and capture/fusion beats confirm VT.
• IV magnesium is first-line for Torsades de Pointes.
• ICD for: aborted arrest, sustained VT with structural disease, high-risk channelopathy.
• CPVT = exercise-induced VT, normal ECG, RYR2 mutation.
• ARVC = epsilon waves, T-wave inversion V1-V3, fibrofatty replacement.
• Repaired TOF = scar-related VT, risk factors: QRS >180ms, LV dysfunction.
• Avoid QT-prolonging drugs in LQTS and drug-induced TdP.
• Amiodarone is first-line for stable monomorphic VT.
• AV dissociation and capture/fusion beats confirm VT.
• IV magnesium is first-line for Torsades de Pointes.
• ICD for: aborted arrest, sustained VT with structural disease, high-risk channelopathy.
• CPVT = exercise-induced VT, normal ECG, RYR2 mutation.
• ARVC = epsilon waves, T-wave inversion V1-V3, fibrofatty replacement.
• Repaired TOF = scar-related VT, risk factors: QRS >180ms, LV dysfunction.
• Avoid QT-prolonging drugs in LQTS and drug-induced TdP.
🗣️ Candidate's role-play & examiner feedback
💬 To the candidate (role‑play): You will be asked the 14 questions from the Examiner Q&A tab. This station tests knowledge of Ventricular Tachycardia – ECG interpretation (wide QRS, AV dissociation, capture/fusion beats), causes (repaired TOF, CPVT, LQTS, ARVC, myocarditis), acute management (amiodarone, cardioversion, magnesium for TdP), long-term management (ICD, ablation, beta-blockers), and family screening. Provide empathetic counseling to parents about prognosis, sports restrictions, and the importance of ICD in high-risk patients.
📝 Examiner Marking Grid (Ventricular Tachycardia – TOACS station):
- ✅ Interprets ECG: wide QRS, AV dissociation, capture/fusion beats (VT)
- ✅ Differentiates VT from SVT with aberrancy
- ✅ Lists causes: structural (TOF, cardiomyopathy, ARVC, myocarditis), channelopathies (CPVT, LQTS, Brugada), metabolic
- ✅ Describes acute management: amiodarone 5 mg/kg IV (stable), cardioversion (unstable), magnesium for TdP
- ✅ States ICD indications: aborted arrest, sustained VT with structural disease, high-risk channelopathy
- ✅ Discusses catheter ablation: curative for idiopathic VT, adjunctive for scar-related VT
- ✅ Explains CPVT (RYR2, exercise-induced, beta-blockers) and ARVC (epsilon wave, ICD)
- ✅ Discusses family screening (ECG, exercise test, genetic testing)
- ✅ Counsels about sports restrictions and lifestyle modifications
📚 Key references: Nelson Textbook of Pediatrics 22e (Chapter 484.4 – Ventricular Tachyarrhythmias), AHA/ACC/HRS Guidelines for VT and ICD, Pediatric EP Society recommendations.