Catecholaminergic polymorphic ventricular tachycardia

Background

• Rare genetic cause of syncope or sudden death in young patients
• Caused by defect in genes involved in intracellular calcium regulation
• Untreated, mortality as high as 35% by age 30
• Structurally normal heart

Clinical Features

• Generally presents between 7-9yo, uncommon to present before 2yo
• Often with family history of known CPVT or sudden unexplained death
• Polymorphic ventricular tachycardia --> syncope/presyncope, palpitations, death
• PVT induced by:
  • Exercise
  • Emotional stress
  • Any other cause of increased catecholamines (e.g. drugs, physiologic stressors)

Differential Diagnosis

• Seizure
• Toxicologic exposure (stimulants or depressant)
• CO poisoning
• Breath-holding spell
• Tet spell
• Cardiac disease
• Pregnancy (especially ectopic)
• Hypoglycemia

Syncope Causes

• Cardiovascular-mediated syncope
  • Dysrhythmias:
    • WPW (pre-excitation)
    • Long QT Syndrome/QT prolongation
    • Brugada Syndrome
    • Catecholaminergic polymorphic ventricular tachycardia
    • 2nd/3rd AV Block
    • Afib/aflutter
    • Vtach/torsades
    • Sick sinus syndrome
    • Arrhythmogenic right ventricular dysplasia
    • Short QT syndrome
  • Cardiovascular disease
    • Valvular Disease (AS, MS, tricuspid stenosis)
    • Aortic Dissection
    • Myocardial Infarction
    • CHF
    • Hypertrophic Cardiomyopathy
    • PE
    • Pericardial Tamponade
    • Myxoma
    • Pulmonary Hypertension
    • Pacemaker malfunction
• Neurally mediated syncope
  • Vasovagal:
    • Fear, pain, emotion, valsalva, breath-holding spell
  • Situational (associated with):
    • Coughing, micturition, defecation, vomiting, swallowing, postexercise
    • Carotid sinus stimulation
• Orthostatic hypotension-mediated syncope:
  • Volume depletion:
    • Dehydration (vomiting, diarrhea)
    • Hemorrhage, (Ectopic Pregnancy, Upper GI Bleed/Lower GI Bleeding, Abdominal Aortic Aneurysm)
    • Sepsis
  • Autonomic Dysreflexia
  • Autonomic failure due to meds
• Other serious causes
  • Stroke
  • SAH
  • TIA
  • Vertebrobasilar Insufficiency
  • Subclavian steal
  • Heat syncope
  • Hypoglycemia
  • Hyperventilation
  • Asphyxiation
  • Seizure
  • Narcolepsy
  • Psychogenic (anxiety, conversion disorder, somatic symptom disorder)
  • Toxic (drugs, carbon monoxide, etc.)

Evaluation

• Baseline ECG normal or maybe slightly long QTc
• During (symptomatic) catecholaminergic episodes
  • Increased HR leads to progressive ventricular ectopy --> isolated PVCs--> bigeminy--> runs of nonsustained vtach--> sustained Vtach/polymorphic ventricular tachycardia
• Echocardiography will show normal heart

Management

Acute

• IV beta blockers first line
• Consider magnesium
• Avoid epinephrine

Long-term

• Beta blockers, often nadalol
• ICD if fail medications or presents with cardiac arrest
• Flecainide
• Verapamil
• Left cardiac sympathetic denervation (!)
• Avoid competitive sports and other stimulants

Disposition

• Likely admit