Premature Beats

Key Features

• Atrial premature beats

  • Triggered by an ectopic focus in the atrium

  • One of the most common premature beats occurring in pediatric patients, particularly during the fetal and newborn periods

• Junctional premature beats: Arise in the atrioventricular node or the bundle of His

• Ventricular premature beats

  • Sometimes referred to as premature ventricular contractions (PVC) or as ventricular ectopy

  • Relatively common, occurring in 1%–2% of patients with normal hearts

  • Characterized by an early beat with a wide QRS complex, without a preceding P wave, and with a full compensatory pause following this early beat

  • Multifocal ventricular premature beats

    • Always abnormal and may be more dangerous

    • May be associated with drug overdose (tricyclic antidepressants or digoxin toxicity), electrolyte imbalance, myocarditis, or hypoxia

Clinical Findings

• Ventricular premature beats

  • Beats originating from a single ectopic focus all have the same configuration

  • Beats of multifocal origin show varying configurations

  • Usually benign in otherwise healthy patients

  • If exercise results in an increase or coupling of contractions, underlying disease may be present

Diagnosis

• Atrial premature beats

  • May be conducted to the ventricle and therefore followed by a QRS complex

  • May be nonconducted, as the beat has occurred so early that the AV node is still refractory

  • A brief pause usually occurs until the next normal sinus beat occurs

• Junctional premature beats induce a normal QRS complex with no preceding P wave

• Ventricular premature beats

  • 24-hour ambulatory ECG

  • Significance of ventricular premature beats can be confirmed by having the patient exercise; as heart rate increases, benign ventricular premature beats usually disappear

  • Echocardiogram may be performed to evaluate ventricular function

Treatment

• Atrial premature beats: Benign and require no treatment when an isolated finding

• Junctional premature beats: Usually benign and require no specific therapy

• Ventricular premature beats: Treatment is directed at correcting the underlying disorder