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Essentials of Diagnosis
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Most patients with sudden cardiac death have underlying coronary heart disease
In the absence of reversible cause, implantable cardioverter defibrillator (ICD) is recommended
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General Considerations
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Sudden cardiac arrest: defined as the successful resuscitation of ventricular fibrillation, either spontaneously or via intervention (defibrillation)
Sudden cardiac death: defined as unexpected nontraumatic death in clinically well or stable patients who die within 1 hour after onset of symptoms; the causative rhythm in most cases is ventricular fibrillation
A disproportionate number of sudden deaths occur in the early morning hours; this suggests that there is a strong interplay with the autonomic nervous system
Prompt evaluation to exclude reversible causes of sudden cardiac arrest should begin immediately following resuscitation
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Underlying coronary heart disease
Initiating arrhythmia in most patients is unknown, but is presumed to be
Sustained monomorphic ventricular tachycardia
Polymorphic ventricular tachycardia
Primary ventricular fibrillation (especially in the setting of acute ischemia)
Complete heart block and sinus node arrest may also cause sudden death
Other forms of structural heart disease can predispose to sudden cardiac death including
Idiopathic cardiomyopathy
Hypertrophic cardiomyopathy
Valvular heart disease (aortic stenosis, pulmonic stenosis)
Congenital heart disease
Arrhythmogenic right ventricular cardiomyopathy
Myocarditis
Five to ten percent of cases of sudden cardiac death are primarily arrhythmic and occur in the absence of structural heart disease; etiologies include
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Laboratory testing
Should be performed to exclude severe electrolyte abnormalities (particularly hypokalemia and hypomagnesemia), acidosis, and to evaluate cardiac biomarkers
Abnormalities may be secondary to resuscitation and not causative of the event; use caution in attributing cardiac arrest solely to an electrolyte disturbance
A 12-lead ECG should be performed to evaluate for ongoing ischemia or conduction system disease
Echocardiography should be done to evaluate ventricular function
Coronary arteriography should be performed to exclude coronary disease as the underlying cause, since revascularization may prevent recurrence
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Intervention is required unless ventricular fibrillation
Occurs shortly after myocardial infarction
Is associated with ischemia
Is seen with a correctable process (eg, electrolyte abnormality or medication toxicity)
Hypothermia protocol should be initiated rapidly and continued for 24–36 hours after cardiac arrest
ICD is generally indicated in patients who survive sudden cardiac arrest
Sudden cardiac arrest in the setting of acute ischemia or infarct should be managed with prompt coronary revascularization
Wearable defibrillator vest