Description

• Atrial dysrhythmia (most commonly with atrial rate of 300 with a 2:1 block leading to a ventricular rate of 150)
• Estimated 200,000 new cases each year
• A macroreentrant circuit in the right atrium is thought to be the underlying mechanism
• Most sensitive rhythm to cardioversion
• Seldom occurs in the absence of organic heart disease
• Less common than supraventricular tachycardia (SVT) or atrial fibrillation
• Typically paroxysmal, lasting seconds to hours
• Occurs in ∼25–35% of patients with atrial fibrillation
• Untreated, may promote cardiomyopathy

Etiology

• Alcoholism
• Cardiomyopathies and myocarditis
• CHF
• Electrolyte abnormalities
• Ischemic heart disease
• Pulmonary embolus and other pulm diseases
• Valvular heart diseases
• Post op following cardiac surgery (often in first postoperative week)
• Thyrotoxicosis

• Occurs in children but is often asymptomatic
• Associated mortality is highest in the neonatal period
• Associated with:
  • Congenital heart disease
  • Infectious etiologies, such as rheumatic fever or myocarditis
• Be sure to consider potential toxic ingestions in pediatric patients with new AV block