Rosen & Barkin's 5-Minute Emergency Medicine Consult (133 page)

ECG findings:

• Abnormal in >90% pts with HCM
  
• T-wave inversion >1 mm 2 or + leads V2-V6, II and aVF, or I and aVL or deep TWI in V4-V6 in non-African-Caribbean descent athletes >16 yo
  
• ST-segment depression >0.5 mm in 2 or more leads requires further investigation
  
• Q-waves >3 mm in depth or >40 ms duration in at least 2 leads other than III & aVR
  
• P-wave >120 ms leads I or II with negative portion ≥1 mm and ≥40 ms in lead V1
  
• Nonspecific IVCD >140 ms
  

• Clinical lab testing is of no assistance.
  
• Genetic testing may help in outpatient workup, but not in ED.
  

• CXR:
  
  • Normal in the vast majority
    
  • Bulge along left heart border representing hypertrophy of free wall of LV
    
  • Right or left atrial enlargement
    
  • Pulmonary vascular redistribution
    
• Transthoracic cardiac echo/Doppler:
  
  • LV wall >15 mm, with normal or small LV cavity (13–14 mm with other features; e.g., family history in adults), in children ≥2 times standard deviation above mean for age, sex, size
    
  • Systolic outflow obstructions
    
  • Diastolic filling abnormalities
    
• Cardiovascular magnetic resonance (CMR)
  
  • Supplements ECHO
    
  • Allows more structural detail for evidence of fibrosis
    
• Stress thallium and PET evaluate ischemia.
  

No ED-based procedures are of diagnostic utility.

• Vagal and other causes of syncope and presyncope
  
• Heatstroke
  
• Aortic stenosis
  
• Pulmonic stenosis
  
• Ventricular septal defect
  
• Mitral regurgitation
  
• Mitral valve prolapse
  
• Arteriosclerotic coronary vascular disease
  
• Differentiate in patients presenting with CHF or angina:
  
  • More ominous in the setting of HCM
    

TREATMENT

• ABCs
  
• IV catheterization
  
• Supplemental oxygen
  
• Cardiac monitor
  
• Pulse oximetry
  

• Depends on type of presentation: Dysrhythmia, cardiac failure, chest pain or ischemia
  
• Underlying principle to understand sensitivity to any situation that may impair cardiac filling.
  
• Patient may need to remain supine.
  
• Standard CHF or anginal vasodilator therapy may lead to cardiovascular collapse; if this occurs, treat with fluid bolus.
  
• Attention to any hypovolemia as small degree may significantly impair cardiac output.
  
• Control rate and improve diastolic filling (underlying principle in treating HCM-associated CHF and angina):
  
  • β-Blockers:
    
    • Mainstay of therapy
      
    • Decrease dysrhythmias and lower elevation of pressure gradient across the LV outflow tract
      
  • Calcium channel blockers:
    
    • Verapamil reduces obstruction by decreasing contractility and improving diastolic relaxation and filling.
      
    • Nifedipine relatively contraindicated due to vasodilatation
      
• Dysrhythmia management:
  
  • β-Blockers and calcium channel blockers 1st line for supraventricular dysrhythmias
    
  • Amiodarone:
    
    • Drug of choice for ventricular dysrhythmias
      
    • Used when β-blockers and calcium channel blockers fail
      
  • Electrical cardioversion:
    
    • Use early in HCM with new atrial fibrillation and CHF
      

All medications must be assessed for effect in face of possible outflow track restriction

• Amiodarone: 150 mg over 10 min, then 360 mg over 6 hr, then 540 mg over next 18 hr (peds: 5 mg/kg IV rapid IV/IO bolus, off-label use per manufacturer, but class IIb for VT with a pulse and class indeterminate for VF and pulseless VT, per American Heart Association. Do not use in infants.)
  
• Propranolol: 1–3 mg (peds: 0.01–0.1 mg/kg slow IV push over 10 min; not to exceed 1 mg/dose) slow IV bolus
  
• Verapamil: 2.5 mg (peds: >1 yr: 0.1–0.2 mg/kg/dose over 2 min; repeat q10–30min as needed; not to exceed 5 mg/dose [1st dose] or 10 mg/dose [2nd dose]) IV bolus over 1–2 min, may repeat as 5 mg in 15–30 min
  
• Phenylephrine: 0.1–0.2 mg (peds: 1–20 μg/kg) IV slow bolus for severe hypotension (shock) not responding to fluid bolus. Repeat in 10–15 min as needed or start IV drip to titrate to BP; or other pure vasoconstrictor (i.e., no inotropic effect). Maintenance dose: 0.05 μg/kg/min (peds: 0.1–0.5 μg/kg/min) IV
  

N/A

Diltiazem: 0.25 mg/kg (peds: Contraindicated <12 yr old) IV over 2 min; may repeat in 15 min at 0.35 mg/kg

FOLLOW-UP

• Unexplained syncope, especially in younger adults.
  
• ICU admission:
  
  • Syncopal episodes
    
  • CHF
    
  • Angina
    
  • Hemodynamically significant tachydysrhythmia
    

When increased myocardial wall thickness is an incidental finding during the ED evaluation for another presentation with:

• No history of familial sudden death (proposed guidance—3 generations to rule out in face of suspicion) or personal history of syncope
  
• Need urgent follow-up with a cardiologist
  
• Counsel against any activities that may decrease diastolic filling pending follow-up:
  
  • Counsel against physical exertion until evaluated by cardiologist
    

See “Discharge Criteria.”

See “Discharge Criteria.”

• Increasing awareness of genetic and phenotypic variants with implications in definition of “normal variant”:
  
  • Some authors advocate cardiac ECHO screening for any youth participation in sports.
    
  • Some authors advocate AICD at diagnosis.
    
• If HCM is considered in a patient with syncope, it must be ruled out because it is much more likely to be fatal with repeat episodes.
  

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  J Thorac Cardiovasc Surg
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• Maron BJ, McKenna WJ, Danielson GK, et al. American College of Cardiology/European Society of
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  Guidelines.
  J Am Coll Cardiol.
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  Circulation
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• Spirito P, Autore C. Management of hypertrophic cardiomyopathy.
  BMJ
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CODES

425.18 Other hypertrophic cardiomyopathy

BASICS

• Dilated cardiomyopathy occurring during the last month of pregnancy up to 5 mo following the delivery
  
• Diagnostic criteria (all required):
  
  • Onset of myocardial failure during last month of pregnancy or 1st 5 mo after delivery
    
  • Absence of a specific cause
    
  • Absence of prior cardiac disease
    
• Diagnosis requires strict criteria of echocardiographic dysfunction
  
• Incidence: 3–5/10,000 live births
  
• ∼50% of cases resolve spontaneously
  
• Mortality: 18–56%
  
• Risk factors:
  
  • Older women (>30 yr)
    
  • Multiparous women
    
  • Multiple gestations
    
  • Prolonged tocolytic therapy (>4 wk)
    
  • Obesity
    
  • Preeclampsia
    
  • African American
    
• Systemic and pulmonary embolism more frequent than with other forms of cardiomyopathy
  
• Factors indicating a poor prognosis:
  
  • Lower left ejection fraction at 6 mo postpartum
    
  • Onset >2 wk postpartum
    
  • Age >30 yr
    
  • African American descent
    
  • Multiparity