Rosen & Barkin's 5-Minute Emergency Medicine Consult (131 page)

BASICS

Diseases of the myocardium associated with cardiac dysfunction:

• Dilated:
  
  • Idiopathic in 25% of all cases of heart failure
    
• Hypertrophic
  
• Restrictive
  
• Arrhythmogenic right ventricular (RV)
  
• Unclassified cardiomyopathy
  
• Specific cardiomyopathy:
  
  • Heart muscle disease associated with a systemic disease or condition
    

• Genetic: 20–30%
  
• Acquired
  
• Idiopathic
  

• Dilated:
  
  • Idiopathic
    
  • Viral
    
  • Genetic/toxic
    
  • Immune
    
  • Familial
    
• Hypertrophic:
  
  • Familial disease with autosomal dominance
    
• Restrictive:
  
  • Idiopathic
    
  • Amyloid
    
• Arrhythmogenic RV:
  
  • Familial disease with dominant and recessive patterns
    
• Specific infectious:
  
  • Lyme disease
    
  • Viral
    
  • Chagas disease
    
  • HIV
    
• Toxic agents:
  
  • Alcohol
    
  • Chemotherapeutic agents
    
• Peripartum
  
• Metabolic:
  
  • Hyperthyroidism
    
  • Pheochromocytoma
    
  • Takotsubo (stress catecholamine)
    
• General system diseases:
  
  • Lupus
    
  • Scleroderma
    
  • Neuromuscular diseases
    
  • Amyloidosis
    

• Idiopathic
  
• Genetic:
  
  • Inborn errors of metabolism
    
  • Malformation syndromes
    
  • Neuromuscular disease
    
  • Familial isolated cardiomyopathy disorders
    
• Acquired:
  
  • Vitamin and/or trace mineral deficiencies
    
  • Electrolyte disturbances
    
  • Endocrine disorders
    
  • Toxins
    
  • Collagen vascular disease
    
  • Immunologic disease
    
  • Malignancy
    
  • Morbid obesity
    
  • Myocarditis
    
  • Pulmonary disease
    
  • Kawasaki disease
    
  • Infection
    
  • Radiation
    
  • Congenital heart disease
    
  • Asphyxia
    

DIAGNOSIS

• Antecedent illness or exposure:
  
  • Chemotherapy
    
  • HIV
    
  • Lyme disease
    
  • Viral
    
• Underlying systemic condition:
  
  • Hemochromatosis
    
  • Sarcoidosis
    
  • Pregnancy
    
• Substance abuse history
  
• Family history:
  
  • Familial sudden death
    
• Exertional complaints (syncope, dyspnea)
  
• Dizziness
  
• Near syncope and syncope
  
• Palpitations
  
• Sudden death
  
• Ventricular arrhythmias
  
• CHF
  

• Irritability
  
• Hepatomegaly
  
• Generalized muscle weakness
  
• Acute biochemical crisis
  
• Hypoglycemia
  
• Metabolic acidosis
  
• Hyperammonemia
  
• Cyanosis
  
• Encephalopathy
  
• Dysmorphic features
  

See Cardiomyopathy, Peripartum.

• Vital signs
  
• Cardiopulmonary exam
  
• Abdominal organomegaly
  
• Edema
  
• Other:
  
  • Rash
    
  • Goiter
    
  • Systemic illness
    

• CBC
  
• Chemistry panel
  
• Liver function tests, thyroid function tests
  
• Cardiac biomarkers
  
• Brain (B-type) natriuretic peptide: Level >100 pg/mL
  
• Serologies: Not useful in the ED
  

• CXR:
  
  • Dilated cardiomyopathy:
    
    • Cardiomegaly
      
    • Pulmonary congestion
      
    • Pleural effusions
      
  • Hypertrophic cardiomyopathy (HCM):
    
    • See Cardiomyopathy, Hypertrophic.
      
  • Restrictive cardiomyopathy:
    
    • Normal cardiac silhouette
      
    • Pulmonary congestion
      
• Emergency transthoracic 2D echocardiography by emergency physician:
  
  • Depressed LV ejection fraction (EF)
    
  • Excludes pericardial tamponade
    
• Formal echocardiography:
  
  • Study of choice
    
  • Identification of underlying disease
    
• Nuclear scintigraphy:
  
  • When ECG is indeterminate
    
  • Determination of the thickness of the septum and free wall
    
  • Alternatives to echocardiography
    
• CT and MRI distinguish between constrictive pericarditis and restrictive cardiomyopathy.
  
• MR comprehensive assessment of heart failure: Assess myocardial anatomy, regional and global function, and viability. Allows assessment of perfusion and acute tissue injury (edema and necrosis), and nonischemic heart failure, fibrosis, infiltration, and iron overload can be detected.
  

EKG:

• HCM:
  
  • Left ventricle (LV) hypertrophy
    
  • Q-waves in leads II, III, aVF, V5, and V6 in the early teenage years (most specific)
    
• Dilated, Lyme, Chagas, and toxic cardiomyopathies:
  
  • Atrial fibrillation
    
  • Heart block
    
  • Conduction abnormalities
    
  • Pseudoinfarct pattern with pathologic Q-waves in anterior and inferior leads without coronary artery disease
    

• Electrolytes
  
• pH
  
• Glucose
  
• Ammonia level
  
• Cardiac output
  
• Dysmorphic evaluation
  
• EKG
  
• Echocardiogram:
  
  • Genetic workup; see individual causes
    

• Other causes of dyspnea:
  
  • Chronic obstructive pulmonary disease
    
  • Anemia
    
  • Asthma
    
  • Interstitial lung disease
    
  • Pulmonary embolism
    
  • Pericardial tamponade
    
  • Valvular heart disease
    
  • Ischemic heart disease
    
  • Hypothyroidism
    
  • Constrictive pericarditis, commonly confused with restrictive cardiomyopathy
    
• Other causes of syncope:
  
  • Hypovolemia
    
  • Heat disorder
    
  • Hypoglycemia
    
  • Arrhythmia
    
  • Cardiac ischemia
    

TREATMENT

• Monitor
  
• Oxygen
  
• Avoid or use a lower dose of nitroglycerin in suspected HCM
  
• Decompensated heart failure:
  
  • Nitroglycerin
    
  • Noninvasive positive-pressure ventilation
    

Airway, breathing, and circulation:

• Control airway as needed.
  
• Supplemental oxygen
  
• Noninvasive positive-pressure ventilation
  

• Anticoagulation:
  
  • Dilated cardiomyopathy
    
  • Standard treatment of atrial fibrillation
    
  • Systemic embolization
    
• Limited ED experience with agents effective in HCM:
  
  • Disopyramide to reduce obstruction
    
  • Amiodarone to convert and maintain sinus rhythm
    
• Standard treatment of CHF
  
• Standard treatment of dysrhythmias
  

• Amiodarone: 5 mg/kg over 10 min
  
• Carnitine: (Peds: 50–300 mg/kg/d PO or IV)
  
• Digoxin: Start 0.125 mg IV
  
• Diltiazem IV: 0.25 mg/kg actual body weight over 2 min (average adult dose: 20 mg); repeat bolus dose (may be administered after 15 min if the response is inadequate): 0.35 mg/kg actual body weight over 2 min (average adult dose: 25 mg); continuous infusion 10 mg/hr; rate may be increased in 5 mg/hr increments up to 15 mg/hr as needed
  
• Disopyramide: 100–200 mg PO q6h
  
• Esmolol IV: Loading dose: 500 μg/kg over 1 min; follow with a 50 μg/kg/min infusion for 4 min; infusion may be continued at 50 μg/kg/min or, if the response is inadequate, titrated upward in 50 μg/kg/min increments (increased no more frequently than q4min) to a max. of 200 μg/kg/min
  
• Furosemide: 20–40 mg IV to a max. of 200 mg on subsequent doses (peds: 1 mg/kg IV q12–24h)
  
• Heparin: Load 80 IU/kg IV; then 18 IU/kg/hr
  
• Metoprolol IV: 2.5–5 mg q2–5min (max. total dose: 15 mg over a 10–15-min period)
  
• Milrinone: Bolus 50 μg/kg IV over 10 min, then 0.375–0.75 μg/kg/min IV
  
• Nesiritide: Bolus 2 μg/kg IV, then 0.01 μg/kg/min IV with a max. of 0.03 μg/kg/min
  
• Nitroglycerin: 5 μg/min IV titrate to SBP