Rosen & Barkin's 5-Minute Emergency Medicine Consult (85 page)

Read Rosen & Barkin's 5-Minute Emergency Medicine Consult Online

Authors: Jeffrey J. Schaider,Adam Z. Barkin,Roger M. Barkin,Philip Shayne,Richard E. Wolfe,Stephen R. Hayden,Peter Rosen

Tags: #Medical, #Emergency Medicine

BOOK: Rosen & Barkin's 5-Minute Emergency Medicine Consult
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ICD9
  • 334.2 Primary cerebellar degeneration
  • 334.3 Other cerebellar ataxia
  • 781.3 Lack of coordination
ICD10
  • G11.1 Early-onset cerebellar ataxia
  • G11.9 Hereditary ataxia, unspecified
  • R27.0 Ataxia, unspecified
ATRIAL FIBRILLATION
Edward Ullman
•
Terrance T. Lee
BASICS
DESCRIPTION
  • Dysrhythmia characterized by seemingly disorganized atrial depolarizations without effective atrial contraction
  • Caused by multiple re-entrant waveforms within the atria
  • Atrial rate ranges from 350–600 beats per minute (bpm).
  • Results in loss of organized atrial contractions and rapid ventricular rate:
    • Decrease in cardiac output
    • Prone to embolus formation
  • Most common clinical arrhythmia:
    • Prevalence increasing with age
    • Men are at higher risk
ETIOLOGY
  • Systemic disease:
    • HTN
    • Hyperthyroidism
    • Chronic pulmonary disease
    • Infection
    • Pulmonary embolus
    • Hypoxia
    • Drugs (e.g., sympathomimetics)
    • Acute alcohol ingestion (holiday heart syndrome)
    • Obesity
    • Electrolyte disturbance
    • Thyroid disease
  • Underlying cardiac disease:
    • Cardiomyopathy
    • CAD
    • Valvular disease, especially mitral
    • Pericarditis
    • Sick sinus syndrome
    • Myocardial contusion
    • CHF
    • Congenital heart disease
  • Idiopathic:
    • Absence of any known etiologic factor
    • No clinical or echocardiographic evidence of heart disease
DIAGNOSIS
SIGNS AND SYMPTOMS
  • Palpitations
  • Decreased cardiac output:
    • Weakness
    • Light headedness
    • Syncope
    • Hypotension
    • Angina
    • Pulmonary edema
    • Altered mental status
    • Lower extremity edema
    • Hepatojugular reflex
  • Embolus formation:
    • Acute neurologic injury
    • Mesenteric ischemia
History
  • Onset of symptoms
  • Duration
  • Inciting factors
  • Prior episodes of fibrillation
  • Prior heart disease
Physical-Exam
  • Palpitations
  • Irregularly irregular pulse
  • Absence of A
    -
    waves in the jugular venous pulse
  • Pulse deficit with more rapid ventricular rates:
    • The auscultated or palpated apical rate is faster than the rate palpated at the wrist
ESSENTIAL WORKUP
  • History and physical exam:
    • Assess for instability and need for immediate cardioversion
    • Duration of symptoms >48 hr or <48 hr
    • Evidence of systemic disease or underlying cardiac disease
  • ECG: Signs of congestive heart failure
    • Absent P-waves replaced by fibrillatory (f) waves, 350–600 bpm
    • F-waves vary in amplitude, morphology, and intervals
    • R-R intervals are irregularly irregular
    • Absence of an isoelectric baseline
    • Ventricular rate ranges from 80–150 bpm:
      • If rate >200 associated with wide-irregular QRS, consider bypass tract
    • Slower rate suggests abnormal AV node or presence of AV nodal blocking medication
    • Usually narrow QRS complexes unless:
      • Functional aberration
      • Pre-existing bundle branch
      • Pre-excitation with an accessory pathway
DIAGNOSIS TESTS & NTERPRETATION
Lab
  • CBC
  • Electrolytes
  • Cardiac enzymes—if ischemia is a concern
  • Thyroid function
  • Digoxin level—if patient is taking
  • Anticoagulation parameters
  • Urine drug screen
Imaging
  • CXR
  • ECG
DIFFERENTIAL DIAGNOSIS
  • Atrial flutter with variable AV block
  • Multifocal atrial tachycardia
  • Sinus rhythm with frequent premature atrial contractions
  • Atrial tachycardia with variable AV block
TREATMENT
PRE HOSPITAL
  • IV access
  • Monitor
  • Oxygen
  • Cardioversion:
    • In settings where patient is unstable
INITIAL STABILIZATION/THERAPY
  • IV
  • Oxygen
  • Monitor
  • Immediate synchronized electrical cardioversion starting at 200 J if the patient is unstable
ED TREATMENT/PROCEDURES
  • Hemodynamically unstable and life threatening:
    • Myocardial infarction, pulmonary edema, heart failure that does not respond promptly to pharmacological measures
    • Synchronized electrical cardioversion
      • Biphasic: Start at 100 J, higher success rate
      • Monophasic: Start at 200 J
      • Sx duration <48 hr: Consider IV heparin bolus prior.
      • Sx duration >48 hr: IV heparin, transesophageal echo to exclude atrial clot, cardioversion. Anticoagulate for 4 wk. Do not delay echo if life-threatening arrhythmia.
      • Consider pretreatment with antiarrhythmic drugs and use anterior–posterior pad placement to increase likelihood of success
    • Chemical cardioversion:
      • Choice of drug depends on history of CHF, high BP, LV hypertrophy, and CAD
      • Medications may be proarrhythmic and should be used with caution
      • As with electrical cardioversion, appropriate anticoagulation will be necessary depending on the duration and presence/absence of clot
      • Ibutilide
      • Procainamide
      • Flecainide
      • Propafenone
      • Sotalol
  • Hemodynamically stable, mildly symptomatic:
    • Treat underlying cause if 1 is identified.
    • Identify if symptoms are <48 hr. If so consider synchronized cardioversion.
    • >48 hr: Rhythm control does not offer mortality benefit over rate control
    • Use procainamide to treat stable patients with a suspected bypass tract
    • Rate control:
      • Not necessary if rate <100 bpm or if rhythm spontaneously converts to sinus
      • AV nodal blockers (calcium channel blockers, β-blockers, and digoxin) contraindicated if bypass tract suspected such as WPW
      • Calcium channel blockers: Consider in patient with pulmonary disease. Use cautiously in patient with uncompensated CHF and 2nd- or 3rd-degree heart block
      • β-blockers: Consider in patient with coronary artery disease (CAD). Use cautiously in patient with uncompensated CHF, 2nd- or 3rd-degree heart block, and pulmonary disease
      • Digoxin: Consider in patient with pre-existing CHF.
      • Amiodarone: Consider in refractory atrial fibrillation
    • Rhythm control and prophylaxis:
      • Includes procainamide, sotalol, amiodarone, dofetilide
      • Amiodarone: Only agent with strong data to support initiation for outpatient treatment
    • Elective cardioversion:
      • Oral anticoagulation with therapeutic levels for 3 wk prior to and 4 wk after
    • Stable patients with atrial fibrillation and WPW can be treated with procainamide or ibutilide, although cardioversion may be preferred
  • Anticoagulation determined by CHADS2 scoring:
    • 1 point for each of the following:
      • History of cardiac failure
      • History of HTN
      • Age ≥75 yr
      • Diabetes
    • 2 points for a history of stroke or TIA
    • Score of 0:
      • 81–325 mg/day of aspirin
    • Score of 1:
      • Either 81–325 mg/day of aspirin or adjusted-dose warfarin with a target INR of 2.5
    • Score >1:
      • Adjusted-dose warfarin with a target INR of 2.5 (range 2–3)
    • Adjusted annual stroke rate increases from 1.9% for a CHADS2 score of 0 to 18.2% for a CHADS2 score of 6
    • Aspirin:
      • Patients with contraindications to anticoagulation and unreliable individuals
      • Patients with low stroke risk
MEDICATION
  • Metoprolol:
    • 5–10 mg slow IV push at 5 min intervals to total of 15 mg
    • 25 mg–100 mg oral BID
  • Diltiazem:
    • 0.25 mg/kg IV over 2 min; if unsuccessful, repeat in 15 min as 0.35 mg/kg IV over 2 min; maintenance infusion of 5 mg/h usually started to maintain rate control.
    • 120–300 mg oral daily
  • Digoxin:
    • 0.5 mg IV initially, then 0.25 mg IV q4h until desired effect
  • Esmolol:
    • 0.5 mg/kg over 1 min; maintenance infusion at 0.05 mg/kg/min over 4 min
  • Propranolol:
    • 0.1 mg/kg IV divided into equal doses at 2–3 min intervals
  • Verapamil:
    • 2.5–5 mg IV bolus over 2 min; may repeat with 5–10 mg q15–30min to max. of 20 mg
    • 120–300 mg PO daily
  • Amiodarone:
    • 5–7 mg/kg over 30–60 min, then 1.2–1.8 g/d continuous infusion or in divided PO doses until 10 g total
    • 600–800 mg/d divided dose until 10 g total, then 200–400 mg/d maintenance
  • Procainamide: 15–18 mg/kg loading dose administered as a slow infusion over 30 min. Max.: 1 g. Then 2–6 mg/min infusion.
  • Quinidine gluconate: 324–648 mg PO q8–12h: (extended release tabs)
  • Ibutilide: 1 mg IV for patients >60 kg; 0.01 mg/kg IV for patients <60 kg infused over 10 min; can be repeated once if sinus rhythm not restored within 10 min. Requires normal QTc, no history of torsades, no hypokalemia. Patients must be monitored for 4 h for QT prolongation, Torsades de Pointes, and ventricular tachycardia.
  • Flecainide: 2 mg/kg IV at 10 mg/min PO. Do not give in patients with structural heart disease.
  • Propafenone: 1–2 mg/kg IV at 10 mg/min
  • Sotalol: 75 mg infused IV over 5 h BID if CrCl >60 mL/min. Give QD if CrCl 40–60 mL/min
  • Heparin: Load 80 U/kg IV; infusion at 18 U/kg/h. Dosage adjustment required in obese patients
  • Low-molecular-weight heparin: 1 mg/kg SQ BID
  • Warfarin sodium: 2.5–5 mg/d PO, dosage adjustments based on INR
  • Aspirin: 50–325 mg/d

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