Ventricular Bigeminy
Ventricular bigeminy is a cardiac rhythm characterized by alternating normal sinus beats and premature ventricular complexes (PVCs), creating a pattern where every other beat is a PVC. 1
Definition and Characteristics
Ventricular bigeminy manifests on the ECG as:
- A pattern where each normal sinus beat is followed by a premature ventricular beat
- PVCs appear as premature abnormal QRS complexes that differ from the sinus QRS morphology
- PVCs are not preceded by premature P waves 2
- The abnormal beats originate from the ventricles rather than following the normal conduction pathway
Electrocardiographic Features
- Premature ventricular beats have a QRS morphology different from the patient's normal QRS complex
- In infants, the QRS duration may be normal or slightly prolonged (<0.08 s) but with different morphology from sinus beats 2
- The coupling interval (time between the normal beat and PVC) is often relatively fixed 3
- PVCs occur after the T wave of the preceding normal beat
Clinical Significance and Risk Assessment
Risk stratification for ventricular bigeminy is based on:
High-Risk Features:
- QTc interval >500 ms
- Association with syncope or presyncope
- Evidence of hemodynamic compromise
- Occurrence during exercise
- Family history of sudden cardiac death 1
Moderate-Risk Features:
- Frequent episodes (>10% of total heartbeats)
- Mild symptoms (palpitations)
- Underlying cardiac disease 1
Low-Risk Features:
- Asymptomatic presentation
- Normal cardiac structure and function
- Normal QT interval
- Suppression of bigeminy with exercise 1
Underlying Causes
Ventricular bigeminy may be associated with:
- Normal hearts (idiopathic)
- Coronary artery disease/myocardial ischemia
- Cardiomyopathies (hypertrophic, dilated)
- Electrolyte abnormalities
- Thyroid dysfunction
- Medication effects
- Altered autonomic tone
- Hypoxia 1, 4
Evaluation
For patients with ventricular bigeminy, the following evaluations should be considered:
- 12-lead ECG to evaluate QT interval and assess for other abnormalities
- Echocardiogram to determine ventricular function and structural abnormalities 2
- 24-hour Holter monitoring for complex ventricular arrhythmias 2
- Exercise stress testing, particularly for high-risk patients
- Laboratory tests to identify electrolyte abnormalities or thyroid dysfunction 1
Management Approach
Management depends on risk stratification and symptoms:
Asymptomatic Patients with Normal Hearts:
- No specific antiarrhythmic therapy is required 1
- Avoidance of potential triggers (caffeine, alcohol, stress)
- Reassurance and follow-up
Symptomatic Patients:
- Consider beta-blockers for symptom control 1
- For persistent symptoms, sodium channel blockers (Class IC agents) may be considered
- Correction of underlying causes (electrolyte abnormalities, ischemia, etc.)
High-Risk Patients:
- Consultation with a cardiologist/electrophysiologist
- Consider antiarrhythmic therapy
- Evaluation for implantable cardioverter-defibrillator if associated with high-risk features 1
Special Considerations
- In patients with long QT syndrome and ventricular bigeminy, withdrawal of QT-prolonging drugs and correction of electrolyte abnormalities are essential 1
- For bigeminy associated with acute coronary syndromes, prompt coronary revascularization is recommended 1
- Ventricular bigeminy may be a precursor to more serious arrhythmias in patients with structural heart disease or prolonged QT intervals 3
Prognosis
- In patients with structurally normal hearts, ventricular bigeminy generally has a benign prognosis 4
- In patients with underlying cardiac disease, especially coronary artery disease or cardiomyopathy, ventricular bigeminy may be associated with increased mortality risk 4
- The presence of complex ventricular arrhythmias in patients with prior myocardial infarction carries a worse prognosis 4