Ventricular Tachyarrhythmias (VT) in Children

VT Introduction Etiology Classification Clinical Presentation Diagnosis Management Prognosis

Introduction to Ventricular Tachyarrhythmias in Children

Ventricular tachyarrhythmias are abnormal heart rhythms originating from the ventricles that can be life-threatening in children. These arrhythmias are characterized by a rapid heart rate (typically >120 beats per minute) and can lead to hemodynamic instability if left untreated. While less common than supraventricular tachycardias in the pediatric population, ventricular tachyarrhythmias require prompt recognition and management due to their potential for sudden cardiac death.

The incidence of ventricular tachyarrhythmias in children is estimated to be 1-2 per 100,000 per year, with a higher prevalence in those with underlying structural heart disease or channelopathies. Understanding the etiology, classification, clinical presentation, and management strategies is crucial for healthcare providers dealing with pediatric patients.

Etiology of Ventricular Tachyarrhythmias in Children

The causes of ventricular tachyarrhythmias in children can be broadly categorized into:

1. Structural heart disease:
   • Congenital heart defects (e.g., Tetralogy of Fallot, transposition of great arteries)
   • Cardiomyopathies (hypertrophic, dilated, restrictive)
   • Myocarditis
2. Inherited arrhythmia syndromes (channelopathies):
   • Long QT syndrome
   • Brugada syndrome
   • Catecholaminergic polymorphic ventricular tachycardia (CPVT)
   • Short QT syndrome
3. Acquired causes:
   • Electrolyte imbalances (hypokalemia, hypomagnesemia)
   • Drug toxicity (e.g., digoxin, antiarrhythmic drugs)
   • Trauma (commotio cordis)
   • Systemic diseases affecting the heart (e.g., rheumatic fever)
4. Idiopathic ventricular tachycardia:
   • Right ventricular outflow tract (RVOT) tachycardia
   • Left ventricular fascicular tachycardia

Understanding the underlying etiology is crucial for appropriate management and long-term prognosis.

Classification of Ventricular Tachyarrhythmias in Children

Ventricular tachyarrhythmias can be classified based on various criteria:

1. Morphology:
   • Monomorphic ventricular tachycardia (uniform QRS complexes)
   • Polymorphic ventricular tachycardia (varying QRS complexes)
2. Duration:
   • Sustained (lasting >30 seconds or requiring intervention)
   • Non-sustained (self-terminating within 30 seconds)
3. Hemodynamic stability:
   • Stable (adequate cardiac output maintained)
   • Unstable (compromised cardiac output, hypotension, altered mental status)
4. Specific types:
   • Ventricular fibrillation (VF)
   • Torsades de pointes
   • Bidirectional ventricular tachycardia
   • Accelerated idioventricular rhythm

This classification helps in determining the appropriate management strategy and assessing the risk of sudden cardiac death.

Clinical Presentation of Ventricular Tachyarrhythmias in Children

The clinical presentation of ventricular tachyarrhythmias in children can vary widely, depending on the type, duration, and hemodynamic consequences of the arrhythmia. Common symptoms and signs include:

• Palpitations: Sensation of rapid or irregular heartbeats
• Chest pain or discomfort
• Shortness of breath
• Dizziness or lightheadedness
• Syncope or near-syncope
• Fatigue or weakness
• Pallor or cyanosis
• Altered mental status
• Seizures (in severe cases)

In infants and young children, nonspecific symptoms such as poor feeding, irritability, or lethargy may be the only indicators. In some cases, ventricular tachyarrhythmias may be asymptomatic and discovered incidentally during routine examinations or screening.

Physical examination findings may include:

• Tachycardia (heart rate often >200 bpm in children)
• Irregular pulse
• Hypotension
• Signs of poor perfusion (prolonged capillary refill, cool extremities)
• Gallop rhythm or S3 heart sound
• Signs of underlying heart disease (e.g., murmurs, heaves)

It's important to note that some children, particularly those with catecholaminergic polymorphic ventricular tachycardia (CPVT), may present with symptoms primarily during physical exertion or emotional stress.

Diagnosis of Ventricular Tachyarrhythmias in Children

Diagnosing ventricular tachyarrhythmias in children requires a combination of clinical assessment and diagnostic tests:

1. Electrocardiogram (ECG):
   • 12-lead ECG is the primary diagnostic tool
   • Key features: wide QRS complexes (>120 ms), AV dissociation, fusion beats
   • Specific patterns may suggest underlying conditions (e.g., Brugada pattern, long QT)
2. Continuous ECG monitoring:
   • Holter monitor (24-48 hours)
   • Event recorder (up to 30 days)
   • Implantable loop recorder (for long-term monitoring)
3. Exercise stress testing:
   • Particularly useful for CPVT and exercise-induced arrhythmias
   • Can help assess QT interval changes with exertion
4. Echocardiography:
   • Evaluates cardiac structure and function
   • Identifies underlying structural heart disease
5. Cardiac MRI:
   • Provides detailed cardiac anatomy and tissue characterization
   • Useful for diagnosing cardiomyopathies, myocarditis, and scar tissue
6. Electrophysiology study:
   • Invasive procedure to induce and map arrhythmias
   • Helps determine the mechanism and origin of the tachycardia
7. Genetic testing:
   • Recommended for suspected inherited arrhythmia syndromes
   • Can guide management and family screening
8. Laboratory tests:
   • Electrolyte panel (potassium, magnesium, calcium)
   • Cardiac enzymes (troponin, CK-MB)
   • Thyroid function tests
   • Drug levels (if applicable)

The diagnostic approach should be tailored to the individual patient, considering the clinical presentation, family history, and suspected underlying etiology. Early and accurate diagnosis is crucial for appropriate management and prevention of sudden cardiac death.

Management of Ventricular Tachyarrhythmias in Children

Management of ventricular tachyarrhythmias in children involves both acute treatment and long-term prevention strategies:

Acute Management:

1. Hemodynamically unstable VT/VF:
   • Immediate cardiopulmonary resuscitation (CPR) if needed
   • Synchronized cardioversion (0.5-1 J/kg, escalating to 2 J/kg if needed)
   • Defibrillation for VF (2 J/kg, escalating to 4 J/kg)
2. Hemodynamically stable VT:
   • IV amiodarone (5 mg/kg over 20-60 minutes)
   • IV lidocaine (1 mg/kg bolus, followed by infusion)
   • Consider overdrive pacing if other methods fail
3. Torsades de pointes:
   • IV magnesium sulfate (25-50 mg/kg, max 2 g)
   • Correction of underlying causes (e.g., electrolyte imbalances)

Long-term Management:

1. Pharmacological therapy:
   • Beta-blockers (e.g., propranolol, nadolol)
   • Class III antiarrhythmics (e.g., amiodarone, sotalol)
   • Class IC antiarrhythmics (e.g., flecainide) for specific indications
2. Implantable Cardioverter-Defibrillator (ICD):
   • For high-risk patients or those with aborted sudden cardiac death
   • Consider in channelopathies and certain cardiomyopathies
3. Catheter ablation:
   • For focal VT or reentrant VT with a defined substrate
   • Can be curative in idiopathic VT (e.g., RVOT VT)
4. Lifestyle modifications:
   • Avoidance of triggers (e.g., intense exercise in CPVT)
   • Dietary changes (e.g., potassium-rich foods in Long QT syndrome)
5. Treatment of underlying conditions:
   • Management of structural heart disease
   • Correction of electrolyte imbalances
   • Treatment of myocarditis or other systemic diseases

Management should be individualized based on the specific arrhythmia, underlying etiology, and patient characteristics. Close follow-up and periodic reassessment are essential for optimal outcomes.

Prognosis of Ventricular Tachyarrhythmias in Children

The prognosis of ventricular tachyarrhythmias in children varies widely depending on several factors:

• Underlying etiology: Children with structural heart disease or inherited arrhythmia syndromes generally have a more guarded prognosis compared to those with idiopathic VT.
• Type and severity of arrhythmia: Sustained polymorphic VT and VF carry a higher risk of sudden cardiac death compared to monomorphic VT.
• Age at presentation: Very young children and infants may have a more challenging clinical course.
• Response to treatment: Early identification and appropriate management can significantly improve outcomes.
• Compliance with therapy: Adherence to medication regimens and lifestyle modifications is crucial for long-term prognosis.

Specific prognostic considerations include:

1. Idiopathic VT: Generally has a good prognosis, especially after successful catheter ablation.
2. Long QT syndrome: Prognosis has improved with beta-blocker therapy and ICDs, but risk remains throughout life.
3. CPVT: Can be well-controlled with beta-blockers and lifestyle modifications, but carries a risk of sudden death if untreated.
4. Post-operative VT: Prognosis depends on the underlying heart defect and the success of surgical correction.
5. VT in cardiomyopathies: Often associated with progressive heart failure and a higher risk of sudden cardiac death. Prognosis varies depending on the type and severity of cardiomyopathy.
6. Brugada syndrome: Risk stratification is challenging. Symptomatic patients have a poorer prognosis and often require ICD implantation.
7. VT associated with myocarditis: Prognosis can be favorable if the underlying inflammation resolves, but some cases may progress to dilated cardiomyopathy.

Long-term Considerations:

• Recurrence risk: Even with appropriate treatment, there's a risk of arrhythmia recurrence. Regular follow-up and adjustment of management strategies are essential.
• ICD-related issues: Children with ICDs may face device-related complications, inappropriate shocks, and psychosocial challenges as they grow.
• Medication side effects: Long-term antiarrhythmic therapy may have adverse effects on growth, development, and organ function.
• Quality of life: Restrictions on physical activity and the psychological impact of living with a potentially life-threatening condition can affect a child's quality of life.
• Transition to adult care: As pediatric patients reach adulthood, careful transition to adult cardiology services is crucial for continuity of care.

Emerging Therapies and Future Outlook:

Advances in several areas are improving the prognosis for children with ventricular tachyarrhythmias:

• Genetic testing and personalized medicine: Improved understanding of genetic factors allows for more tailored treatment approaches.
• Subcutaneous ICDs: These devices avoid the need for transvenous leads, potentially reducing long-term complications in young patients.
• Advanced mapping and ablation techniques: Improvements in 3D mapping and ablation technologies are making catheter ablation safer and more effective, even in complex cases.
• Novel antiarrhythmic drugs: Research into new medications with better efficacy and safety profiles is ongoing.
• Stem cell therapies: For some forms of cardiomyopathy, regenerative medicine approaches are being investigated to improve cardiac function and reduce arrhythmia burden.

Overall, while ventricular tachyarrhythmias in children remain a significant challenge, advances in diagnosis, risk stratification, and treatment have generally improved outcomes. Early recognition, appropriate management, and ongoing research continue to enhance the prognosis for affected children. However, lifelong cardiac care and vigilance are typically necessary to ensure the best possible outcomes.

Topic Name Monomorphic Ventricular Tachycardia Polymorphic Ventricular Tachycardia Ventricular Fibrillation Torsades de Pointes Catecholaminergic Polymorphic Ventricular Tachycardia Idiopathic Ventricular Tachycardia

Monomorphic Ventricular Tachycardia in Children

Definition and Characteristics:

Monomorphic ventricular tachycardia (VT) is characterized by a regular, wide-complex tachycardia with a consistent QRS morphology. In children, it typically has a rate of 120-250 beats per minute.

Etiology:

• Structural heart disease (e.g., congenital heart defects, cardiomyopathies)
• Post-operative scar tissue
• Myocarditis
• Idiopathic (no apparent structural heart disease)
• Inherited arrhythmia syndromes (less commonly)

Clinical Presentation:

Symptoms can range from palpitations and dizziness to syncope and sudden cardiac arrest, depending on the rate, duration, and underlying cardiac function.

Diagnosis:

• 12-lead ECG showing wide QRS complexes (>120 ms) at a regular rate
• Echocardiography to assess for structural abnormalities
• Cardiac MRI for tissue characterization
• Electrophysiology study for precise localization

Management:

1. Acute treatment:
   • Synchronized cardioversion if hemodynamically unstable
   • IV antiarrhythmic drugs (e.g., amiodarone, lidocaine) if stable
2. Long-term management:
   • Catheter ablation (particularly effective for idiopathic VT)
   • Antiarrhythmic medications
   • ICD implantation for high-risk cases
   • Treatment of underlying heart disease

Prognosis:

Prognosis varies depending on the underlying cause. Idiopathic forms often have an excellent prognosis, especially after successful ablation. Cases associated with structural heart disease may have a more guarded outlook.

Polymorphic Ventricular Tachycardia in Children

Definition and Characteristics:

Polymorphic ventricular tachycardia (VT) is characterized by a rapid, irregular wide-complex tachycardia with beat-to-beat variations in QRS morphology, axis, and amplitude.

Etiology:

• Long QT syndrome (congenital or acquired)
• Catecholaminergic polymorphic ventricular tachycardia (CPVT)
• Severe electrolyte disturbances (e.g., hypokalemia, hypomagnesemia)
• Acute myocardial ischemia (rare in children)
• Drug toxicity
• Severe structural heart disease

Clinical Presentation:

Often presents with syncope, seizure-like activity, or sudden cardiac arrest. May be preceded by palpitations or dizziness.

Diagnosis:

• ECG showing rapid, irregular wide-complex tachycardia with varying QRS morphology
• Genetic testing for inherited arrhythmia syndromes
• Echocardiography to exclude structural heart disease
• Exercise stress testing (particularly for CPVT)

Management:

1. Acute treatment:
   • Immediate defibrillation if pulseless
   • IV magnesium sulfate, particularly for torsades de pointes
   • Correction of electrolyte abnormalities
   • Beta-blockers for CPVT
2. Long-term management:
   • Treatment of underlying condition (e.g., beta-blockers for LQTS and CPVT)
   • ICD implantation for high-risk cases
   • Left cardiac sympathetic denervation (for refractory cases of LQTS or CPVT)
   • Avoidance of QT-prolonging medications in LQTS

Prognosis:

Generally more serious than monomorphic VT. Prognosis depends on the underlying cause and effectiveness of treatment. CPVT and LQTS can have good outcomes with appropriate management, but carry a lifelong risk of arrhythmia.

Ventricular Fibrillation in Children

Definition and Characteristics:

Ventricular fibrillation (VF) is a chaotic, rapid electrical activity of the ventricles resulting in no effective cardiac output. On ECG, it appears as irregular, chaotic waves without discernible QRS complexes.

Etiology:

• Inherited arrhythmia syndromes (e.g., Brugada syndrome, LQTS)
• Severe structural heart disease
• Acute myocarditis
• Commotio cordis
• Severe electrolyte disturbances
• Drug toxicity
• Hypoxia or ischemia

Clinical Presentation:

Presents as sudden cardiac arrest with loss of consciousness, absence of pulse, and cessation of breathing.

Diagnosis:

• Clinical presentation of cardiac arrest
• ECG showing chaotic, irregular electrical activity without QRS complexes
• Post-resuscitation workup to identify underlying cause

Management:

1. Acute treatment:
   • Immediate cardiopulmonary resuscitation (CPR)
   • Defibrillation (2 J/kg, increasing to 4 J/kg if needed)
   • Epinephrine administration
   • Consider antiarrhythmic drugs (e.g., amiodarone) for refractory VF
2. Post-resuscitation care:
   • Targeted temperature management
   • Identification and treatment of underlying cause
   • Neurological assessment and support
3. Long-term management:
   • ICD implantation for most survivors
   • Specific therapy for underlying condition (e.g., beta-blockers for LQTS)
   • Family screening for inherited conditions

Prognosis:

VF is immediately life-threatening. Survival depends on prompt recognition and defibrillation. Neurological outcomes vary based on the duration of arrest and effectiveness of resuscitation. Long-term prognosis depends on the underlying cause and prevention of recurrence.

Torsades de Pointes in Children

Definition and Characteristics:

Torsades de Pointes (TdP) is a specific form of polymorphic ventricular tachycardia characterized by a "twisting of the points" appearance on ECG, with the QRS complexes appearing to twist around the isoelectric line. It is associated with a prolonged QT interval.

Etiology:

• Congenital Long QT syndrome
• Acquired Long QT syndrome:
  • QT-prolonging medications
  • Electrolyte disturbances (hypokalemia, hypomagnesemia, hypocalcemia)
  • Bradycardia
  • Hypothermia
• Structural heart disease (less common in children)

Clinical Presentation:

May present with palpitations, dizziness, syncope, or sudden cardiac arrest. Often occurs in bursts that self-terminate but can degenerate into sustained VF.

Diagnosis:

• ECG showing characteristic "twisting" pattern of QRS complexes
• Prolonged QT interval on baseline ECG
• Genetic testing for congenital LQTS
• Evaluation for acquired causes (medication review, electrolyte panel)

Management:

1. Acute treatment:
   • Defibrillation if sustained or hemodynamically unstable
   • IV magnesium sulfate (25-50 mg/kg, max 2g)
   • Correction of electrolyte abnormalities
   • Temporary pacing to increase heart rate if bradycardia-dependent
2. Long-term management:
   • Beta-blockers for congenital LQTS
   • Avoidance of QT-prolonging medications
   • ICD implantation for high-risk cases
   • Left cardiac sympathetic denervation in selected cases

Prognosis:

Prognosis depends on the underlying cause. Acquired forms may have a good prognosis if the precipitating factor is identified and corrected. Congenital LQTS requires lifelong management but can have a good prognosis with appropriate treatment. Recurrence risk remains a concern, necessitating ongoing vigilance and management.

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) in Children

Definition and Characteristics:

CPVT is an inherited arrhythmia syndrome characterized by exercise or emotion-induced bidirectional or polymorphic ventricular tachycardia in the absence of structural heart disease.

Etiology:

• Genetic mutations affecting cardiac calcium handling:
  • RYR2 gene (autosomal dominant, most common)
  • CASQ2 gene (autosomal recessive)
  • Other rare genetic variants

Clinical Presentation:

Typically presents in childhood or adolescence with syncope or cardiac arrest triggered by physical exertion or emotional stress. Some patients may experience palpitations or dizziness preceding syncope.

Diagnosis:

• Exercise stress test showing characteristic bidirectional or polymorphic VT
• Genetic testing
• Normal resting ECG (unlike LQTS)
• Normal structural cardiac evaluation (echocardiogram, cardiac MRI)

Management:

1. Acute treatment:
   • Beta-blockers to terminate acute episodes
   • Defibrillation if sustained VT or VF occurs
2. Long-term management:
   • High-dose beta-blockers (e.g., nadolol) as first-line therapy
   • Flecainide as add-on therapy for refractory cases
   • ICD implantation for high-risk patients or those with recurrent events despite medical therapy
   • Left cardiac sympathetic denervation for refractory cases
   • Exercise restriction (avoid competitive sports and intense physical activities)
3. Family screening:
   • Genetic testing and clinical evaluation of first-degree relatives

Prognosis:

CPVT is associated with a high risk of sudden cardiac death if untreated. With appropriate management, many patients can have a good quality of life, but lifelong therapy and follow-up are necessary. The risk of arrhythmic events persists into adulthood, requiring ongoing vigilance and adherence to treatment.

Idiopathic Ventricular Tachycardia in Children

Definition and Characteristics:

Idiopathic ventricular tachycardia (IVT) refers to VT occurring in the absence of structural heart disease or inherited arrhythmia syndromes. It typically presents as monomorphic VT and is often amenable to catheter ablation.

Types:

1. Right Ventricular Outflow Tract (RVOT) Tachycardia:
   • Most common form of idiopathic VT in children
   • Typically presents with left bundle branch block, inferior axis morphology on ECG
2. Left Ventricular Fascicular Tachycardia:
   • Often originates from the left posterior fascicle
   • Characterized by right bundle branch block, superior axis morphology
3. Other rare forms:
   • Aortic cusp VT
   • Papillary muscle VT
   • Mitral annular VT

Clinical Presentation:

Symptoms can range from asymptomatic (detected incidentally) to palpitations, dizziness, or rarely syncope. Exercise may trigger or exacerbate symptoms in some cases.

Diagnosis:

• 12-lead ECG during tachycardia
• Holter monitoring or event recorder
• Exercise stress test
• Echocardiography to exclude structural heart disease
• Cardiac MRI in selected cases
• Electrophysiology study for definitive diagnosis and localization

Management:

1. Acute treatment:
   • Vagal maneuvers or adenosine may terminate some forms
   • IV verapamil for fascicular VT
   • Beta-blockers or other antiarrhythmic drugs for RVOT VT
2. Long-term management:
   • Catheter ablation: First-line therapy for most cases, with high success rates
   • Antiarrhythmic medications: Beta-blockers, calcium channel blockers, or class IC antiarrhythmics if ablation is not preferred or unsuccessful
   • Observation: For infrequent, well-tolerated episodes

Prognosis:

Generally excellent prognosis, especially after successful catheter ablation. Recurrence rates are low, particularly for RVOT VT. Fascicular VT may have a slightly higher recurrence rate. The risk of sudden cardiac death is extremely low in true idiopathic VT.

Special Considerations in Children:

• Catheter ablation in young children should be performed at experienced pediatric electrophysiology centers
• Growth and development may affect the long-term success of ablation procedures performed in early childhood
• Regular follow-up is important to ensure the absence of developing structural heart disease or other arrhythmias

Differential Diagnosis:

It's crucial to rule out other causes of VT in children, including:

• Arrhythmogenic right ventricular cardiomyopathy (ARVC)
• Cardiac sarcoidosis
• Myocarditis
• Congenital heart disease
• Inherited arrhythmia syndromes

Careful evaluation and follow-up are essential to confirm the diagnosis of idiopathic VT and exclude these potentially more serious conditions.

Objective QnA: Ventricular Tachyarrhythmias in Children

1. Question: What is the definition of ventricular tachycardia (VT) in children? Answer: Ventricular tachycardia in children is defined as three or more consecutive ventricular beats at a rate > 120 beats per minute.
2. Question: Which congenital heart disease is most commonly associated with ventricular tachycardia in children? Answer: Tetralogy of Fallot repair is most commonly associated with ventricular tachycardia in children with congenital heart disease.
3. Question: What is the most common cause of polymorphic VT in children with structurally normal hearts? Answer: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is the most common cause of polymorphic VT in children with structurally normal hearts.
4. Question: Which inherited channelopathy is associated with bidirectional VT? Answer: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is associated with bidirectional VT, typically induced by exercise or emotional stress.
5. Question: What is the typical ECG appearance of torsades de pointes? Answer: Torsades de pointes appears as a polymorphic VT with characteristic twisting of the QRS complexes around the isoelectric line.
6. Question: Which medication is first-line therapy for hemodynamically stable VT in children? Answer: Amiodarone is often considered first-line therapy for hemodynamically stable VT in children due to its efficacy and relatively low risk of pro-arrhythmia.
7. Question: What is the immediate management for pulseless VT in children? Answer: Immediate defibrillation with 2 J/kg is the first step in managing pulseless VT in children, followed by CPR if unsuccessful.
8. Question: Which imaging modality is preferred for identifying structural abnormalities associated with VT in children? Answer: Cardiac MRI is the preferred imaging modality for identifying structural abnormalities associated with VT in children, such as fibrosis or infiltrative diseases.
9. Question: What is the role of beta-blockers in managing ventricular arrhythmias in children? Answer: Beta-blockers are first-line therapy for many ventricular arrhythmias in children, particularly those associated with long QT syndrome, CPVT, and some forms of idiopathic VT.
10. Question: Which electrolyte abnormality can precipitate ventricular arrhythmias in children? Answer: Hypokalemia can precipitate ventricular arrhythmias in children, particularly in those with underlying channelopathies or on medications that prolong the QT interval.
11. Question: What is the most common site of origin for idiopathic VT in children? Answer: The right ventricular outflow tract is the most common site of origin for idiopathic VT in children.
12. Question: Which genetic syndrome is associated with an increased risk of ventricular arrhythmias and sudden cardiac death in children? Answer: Marfan syndrome is associated with an increased risk of ventricular arrhythmias and sudden cardiac death in children, particularly in those with significant aortic root dilation.
13. Question: What is the role of implantable cardioverter-defibrillators (ICDs) in managing ventricular arrhythmias in children? Answer: ICDs are used for primary or secondary prevention of sudden cardiac death in children at high risk of life-threatening ventricular arrhythmias, such as those with certain channelopathies or cardiomyopathies.
14. Question: Which antiarrhythmic medication is contraindicated in children with Brugada syndrome? Answer: Class IC antiarrhythmic drugs (e.g., flecainide, propafenone) are contraindicated in children with Brugada syndrome as they can unmask or exacerbate the ECG pattern and increase arrhythmia risk.
15. Question: What is the significance of epsilon waves on ECG in children with ventricular arrhythmias? Answer: Epsilon waves are characteristic of arrhythmogenic right ventricular cardiomyopathy (ARVC) and represent delayed activation of the right ventricle due to fibrofatty replacement of myocardium.
16. Question: Which non-invasive test is useful in risk-stratifying children with hypertrophic cardiomyopathy for ventricular arrhythmias? Answer: Ambulatory ECG monitoring (Holter) is useful in risk-stratifying children with hypertrophic cardiomyopathy, as the presence of non-sustained VT is a risk factor for sudden cardiac death.
17. Question: What is the role of catheter ablation in managing ventricular arrhythmias in children? Answer: Catheter ablation can be curative for some forms of idiopathic VT in children and may be used as an adjunct therapy in those with recurrent VT despite medical management.
18. Question: Which medication is used as an adjunct to beta-blockers in children with CPVT who continue to have arrhythmias? Answer: Flecainide is often used as an adjunct to beta-blockers in children with CPVT who continue to have arrhythmias despite maximal beta-blocker therapy.
19. Question: What is the typical ECG appearance of accelerated idioventricular rhythm (AIVR)? Answer: AIVR typically presents as a wide complex rhythm with a rate slightly faster than the underlying sinus rate (usually 60-120 bpm) and often shows fusion or capture beats.
20. Question: Which cardiomyopathy is associated with an increased risk of ventricular arrhythmias in children who are competitive athletes? Answer: Hypertrophic cardiomyopathy is associated with an increased risk of ventricular arrhythmias in children who are competitive athletes, particularly during intense physical exertion.
21. Question: What is the role of left cardiac sympathetic denervation in managing ventricular arrhythmias in children? Answer: Left cardiac sympathetic denervation can be used as an adjunct therapy in children with refractory ventricular arrhythmias, particularly in those with long QT syndrome or catecholaminergic polymorphic ventricular tachycardia.
22. Question: Which metabolic disorder can present with life-threatening ventricular arrhythmias in infants? Answer: Certain fatty acid oxidation disorders, such as very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency, can present with life-threatening ventricular arrhythmias in infants, particularly during fasting or illness.
23. Question: What is the significance of T wave alternans in children with ventricular arrhythmias? Answer: T wave alternans is a marker of electrical instability and may indicate an increased risk of life-threatening ventricular arrhythmias, particularly in children with long QT syndrome or cardiomyopathies.
24. Question: Which antiarrhythmic medication is preferred for treating ventricular arrhythmias in children with significant left ventricular dysfunction? Answer: Amiodarone is often preferred for treating ventricular arrhythmias in children with significant left ventricular dysfunction due to its minimal negative inotropic effect compared to other antiarrhythmic drugs.
25. Question: What is the role of mexiletine in managing ventricular arrhythmias in children? Answer: Mexiletine, a Class IB antiarrhythmic, can be used as an adjunct therapy in children with long QT syndrome type 3 and can also be effective in some cases of idiopathic ventricular tachycardia.
26. Question: Which imaging finding on cardiac MRI is suggestive of arrhythmogenic right ventricular cardiomyopathy (ARVC) in children? Answer: Late gadolinium enhancement in the right ventricular free wall or localized right ventricular aneurysms on cardiac MRI are suggestive of ARVC in children.
27. Question: What is the significance of a short-coupled variant of torsades de pointes in children? Answer: Short-coupled variant of torsades de pointes is a rare but malignant form of polymorphic VT that can occur in children with structurally normal hearts and is characterized by a very short coupling interval of the initiating premature ventricular complex.
28. Question: Which surgical procedure can be considered for children with recurrent ventricular tachycardia originating from a discrete myocardial scar? Answer: Surgical ventricular tachycardia ablation or aneurysmectomy can be considered for children with recurrent ventricular tachycardia originating from a discrete myocardial scar, particularly when catheter ablation has failed or is not feasible.