Does Ventricular Bigeminy (VBI) show up on an Electrocardiogram (EKG)?

Ventricular Bigeminy on Electrocardiogram (EKG)

Yes, ventricular bigeminy (VBI) is clearly visible on an electrocardiogram (EKG) as a pattern of alternating normal sinus beats and premature ventricular contractions (PVCs).

Electrocardiographic Features of Ventricular Bigeminy

Ventricular bigeminy has distinctive characteristics on EKG that make it readily identifiable:

• Pattern: Alternating normal sinus beat followed by a PVC in a 1:1 ratio 1
• QRS morphology: PVCs appear as broad (>110 ms), premature ventricular complexes 1
• Timing: Regular pattern with each normal beat followed by a premature beat 2
• Compensatory pause: Typically shows a full or more than compensatory pause after the PVC 1
• Discordant QRS and T wave axis: The T wave direction is typically opposite to the QRS direction in the PVC 1

Diagnostic Value

Ventricular bigeminy has specific diagnostic significance that can be identified on EKG:

• The number of bigeminy episodes and percentage of PVCs occurring in bigeminy can help differentiate between different cardiac conditions 2
• In a study comparing Andersen-Tawil syndrome patients with post-myocardial infarction patients, those with Andersen-Tawil syndrome had significantly more episodes of bigeminy (median 1038 vs 1) and higher percentage of PVCs in bigeminy (51.1% vs 0.1%) 2

Mechanisms and Clinical Significance

The underlying mechanisms of ventricular bigeminy that can be inferred from EKG patterns include:

• May occur during the third phase of action potential and the supernormal myocardial excitation period 3
• In patients with prolonged ventricular repolarization, bigeminy may be caused by PVCs due to early afterdepolarizations 4
• Often begins after a short-long RR sequence in patients with long QT intervals 4

Risk Stratification Based on EKG Findings

The presence and characteristics of ventricular bigeminy on EKG can help with risk assessment:

• In patients with normal hearts, ventricular bigeminy generally has a benign prognosis 5
• In patients with structural heart disease, ventricular bigeminy may indicate increased risk 5
• A specific ECG tetrad has been identified in high-risk patients: frequent ventricular bigeminy (>5% of total ventricular arrhythmias), long corrected QT interval (>0.5 second), relatively fixed coupling interval, and onset of bigeminy after a short-long RR sequence 4

Clinical Implications

The identification of ventricular bigeminy on EKG has important management implications:

• A PVC burden >15% of total heartbeats can produce reversible left ventricular dysfunction 6
• Low PVC burden (<2,000/24 hours) is generally considered benign 6
• High PVC burden (>10% of total heartbeats) is associated with risk of developing PVC-induced cardiomyopathy 6
• PVCs >2,000/24 hours have a higher association with structural heart disease (30%) 6

Monitoring Recommendations

When ventricular bigeminy is detected on EKG, follow-up monitoring may include:

• Ambulatory Holter monitoring to quantify PVC burden and patterns 6
• Echocardiogram to exclude underlying structural heart disease 6
• Exercise stress testing to assess if PVCs increase with exertion 6
• Regular echocardiographic follow-up in patients with high PVC burden 6

In summary, ventricular bigeminy has a characteristic appearance on EKG that makes it readily identifiable and provides valuable diagnostic and prognostic information for clinical management.