Rosen & Barkin's 5-Minute Emergency Medicine Consult (116 page)

• Inherited heart disease due to mutations of cardiac Na
  ⁺
  channels without structural abnormalities
  
• Very high risk of sudden cardiac death in the form of ventricular fibrillation
  
• 2-yr mortality ∼30%
  
• Suspected in 40–60% of what was previously known as idiopathic ventricular fibrillation
  
• Higher prevalence in men of Southeast Asian descent, but all ages, genders, races can be affected
  

• Inherited:
  
  • Autosomal dominant in 50%
    
  • Variable penetration
    
• Cardiac Na
  ⁺
  channel:
  
  • >70 described mutations
    
  • Variable penetrance
    
  • SCN5A mutations account for 20%
    

DIAGNOSIS

• Most commonly presents as episodes of sudden death (in ventricular fibrillation) or as syncope or near-syncope in self-terminating episodes of polymorphic ventricular tachycardia
  

• HPI:
  
  • Episodes of syncope or near-syncope
    
  • Palpitations
    
  • Cardiac arrest
    
  • Concomitant illness, fever, metabolic, or electrolyte disorders
    
  • Cocaine use
    
  • TCA and psychotropic drugs
    
  • Nocturnal agonal respirations
    
• Family history:
  
  • History of drowning due to syncope or dysrhythmias while submerged
    
  • History of early and/or sudden cardiac death
    
  • Known relatives with Brugada syndrome
    

• Complete physical exam, with special attention to other causes of syncope or dysrhythmia:
  
  • Abnormal heart sounds
    
  • Pectus excavatum (normal variant EKG changes)
    
  • Athletes
    
  • Pacemaker in situ
    

• A 12-lead EKG is imperative
  
• Detailed HPI and family history
  
• Toxicology screen
  

• Basic:
  
  • Right bundle branch block (RBBB) or Incomplete right bundle branch block (IRBBB) with ST-segment elevation in the right precordial leads only
    
• Morphology of QRS-T in V1–V3
  
  • ST-elevation
    
  • Sometimes only in V1 and very rarely in V3
    
• Type 1 (coved pattern):
  
  • Initial ST-elevation ≥2 mm, slowly descending, concave with respect to the isoelectric line
    
  • Negative symmetric T-wave
    
  • No clear r’
    
  • QRS duration mismatch between V1 and V6
    
• Type 2 (saddle back pattern):
  
  • High r’ take-off is ≥2 mm with respect to the isoelectric line
    
  • Followed by ST-elevation – convex with respect to the isolectric line
    
  • QRS duration mismatch between V1 and V6
    

• Serum:
  
  • Chemistries to rule out underlying electrolyte causes of dysrhythmia or syncope
    
  • Cardiac biomarkers (troponin, CK-MB) for ischemia
    
  • D-dimer in the appropriate population (Wells, PERC) if considering pulmonary embolism
    
  • CBC for evaluation of syncope
    

• CXR:
  
  • Evaluate for cardiomegaly
    
• CT-angiogram of the chest:
  
  • If considering pulmonary embolism as a cause
    

• Electrophysiology lab
  
  • Drug challenge with sodium channel blockers (type 1a and 1c)
    
• AICD placement
  
  • Mortality reduced to 0% in this group
    

• Syncope:
  
  • Primary cardiogenic
    
  • Vasovagal
    
  • Neurogenic
    
  • Hypovolemia
    
  • Pregnancy
    
• Dysrhythmias:
  
  • Paroxysmal atrial fibrillation
    
  • Atrial fibrillation with rapid ventricular response
    
  • Wolff–Parkinson–White syndrome
    
  • Lown–Ganong–Levine syndrome
    
  • Ventricular tachycardia
    
  • Multifocal atrial tachycardia
    
  • Spontaneously terminating ventricular fibrillation
    
  • Symptomatic bradycardia
    
  • High-grade heart blocks
    
  • Long QT syndromes
    
  • Overdose especially TCA
    
• EKG mimics:
  
  • Isolated RBBB
    
  • Athletes
    
  • Septal hypertrophy
    
  • Pectus excavatum
    
  • Arrhythmogenic right ventricular dysplasia
    
  • STEMI
    
• Other systemic illness:
  
  • Electrolyte disturbances
    
  • Pericarditis
    
  • Myocarditis
    
  • Myopericarditis
    
  • Pulmonary embolism
    

TREATMENT

• Airway, breathing, and circulation management
  
• ACLS protocol for arrest/dysrhythmias
  

• Airway, breathing, and circulation management
  
• Start or continue ACLS algorithms
  

• Cardiac monitoring at all times
  
• Cardiology consult:
  
  • For electrophysiology evaluation
    
• Defibrillator/pacing pads
  
• Correct underlying disease processes:
  
  • Replete electrolytes
    
  • Correct metabolic derangements
    
  • Asymptomatic patients’ management controversial. Current consensus states EP evaluation but not supported in literature.
    

• ACLS medications per protocol
  
• Antiarrhythmics usually not helpful
  

• PALS/defibrillation
  
• Appropriate weight-based medication and energy (joule) adjustments
  

FOLLOW-UP

• EKG findings concerning for Brugada in the appropriate clinical setting
  
• Unexplained syncope
  
• Inability to obtain rapid cardiology follow-up
  
• Ongoing dysrhythmias even if they are spontaneously terminating
  

• Hemodynamically stable
  
• Asymptomatic
  
• Cardiology clearance
  
• Appropriate AICD intervention after an event
  
  • After interrogation of AICD
    

• All patients with concerning EKG findings and history should be referred to EP for additional evaluation
  

• Consider in any episodes of sudden cardiac death or syncope, especially in the setting of family history of the same
  
• The EKG is diagnostic showing RBBB or IRBBB with ST-segment elevation in the right precordial leads only
  
• Beware of EKG mimics which can have similar presentation – typically mimics will have concordant QRS duration in V1 and V6 whereas Brugada QRS changes should be isolated to V1–V3
  
• Have a low threshold for cardiology consultation given high risk of death
  
• AICD implantation is definitive treatment, almost eliminating risk of sudden cardiac death
  
• Antiarrhythmic agents have not been found to be helpful
  
• The Brugada pattern may be “unmasked” in systemic illness, even if resolution of the EKG occurs, the patient should still have EP follow-up
  

• Bayés de Luna A, Brugada J, Baranchuk A, et al. Current electrocardiographic criteria for diagnosis of Brugada pattern: A consensus report.
  J Electrocardiol
  . 2012;45(5):433–442.
  
• Brady WJ. ST segment and T wave abnormalities not caused by acute coronary syndromes.
  Emerg Med Clin North Am
  . 2006;24(1):91–111, vi. Review.
  
• Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: A distinct clinical and electrocardiographic syndrome.
  J Am Coll Cardiol.
  1992;20:1391–1396.
  
• Mattu A, Rogers RL, Kim H, et al. The Brugada syndrome.
  Am J Emerg Med
  . 2003;21(2):146--151.
  

CODES

746.89 Other specified congenital anomalies of heart

BASICS