Bidirectional Ventricular Tachycardia

Bidirectional ventricular tachycardia

Definitions

• Bidirectional ventricular tachycardia (BVT) is a rare ventricular dysrhythmia characterised by a beat-to-beat alternation of the frontal QRS axis.
• In the example above, you can see the QRS axis shifts 180 degrees from left to right with each alternate beat.
• Another possible pattern is alternating left and right bundle-branch block (see Figure 2 in the paper by Smith et al).

Causes

• This rhythm is most commonly associated with severe digoxin toxicity.
• It may be the presenting rhythm in patients with familialcatecholaminergic polymorphic ventricular tachycardia (CPVT).
• BVT has also been reported with herbal aconite poisoning.

Examples

Multifocal ectopy and bidirectional VT secondary to digoxin poisoning

Another example of bidirectional VT due to digoxin toxicity

Exercise stress test in a patient with CPVT. Progressively worsening ventricular arrhythmias are observed during exercise. Typical bidirectional VT develops after 1 minute of exercise with a sinus heart rate of approximately 120 beats per minute. Arrhythmias rapidly recede during recovery.

Related Topics

• Digoxin toxicity

Further Reading

• ECG BASICS – Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES – Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes – Cheats guide to eponymous emancipation
• ECG Reference Sites on the WEB – the best of the rest

Author Credits

References

• Menduiña MJ, Candel JM, Alaminos P, Gómez FJ, Vílchez J. Bidirectional ventricular tachycardia due to digitalis poisoning. Rev Esp Cardiol. 2005 Aug;58(8):991-3. Spanish [PMID: 16053836] [Full text - English]
• Murray L, Daly F, McCoubrie D, Soderstrom J, Pascu O, Armstrong J, Cadogan M. Toxicology Handbook, Second Edition. Churchill Livingstone (2010).
• Napolitano C, Priori SG, Bloise R. Catecholaminergic Polymorphic Ventricular Tachycardia. 2004 Oct 14 [updated 2009 Jul 7]. In: Pagon RA, Bird TC, Dolan CR, Stephens K, editors. GeneReviews [Internet]. Seattle (WA): University of Washington, Seattle (1993) [PMID: 20301466]
• Richter S, Brugada P. Bidirectional ventricular tachycardia. J Am Coll Cardiol. 2009 Sep 22;54(13):1189. [Full text].
• Smith SW, Shah RR, Hunt JL, Herzog CA. Bidirectional ventricular tachycardia resulting from herbal aconite poisoning. Ann Emerg Med. 2005 Jan;45(1):100-1 [Full text]