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Bidirectional Ventricular Tachycardia

Bidirectional ventricular tachycardia (BVT)

Bidirectional Ventricular Tachycardia

• Bidirectional Ventricular Tachycardia is a polymorphic ventricular tachycardia
• It involves 2 ectopic foci in the ventricles
• Which alternately generate impulses
• Ventricular Extrasystole (VES)
• In the right ventricle triggers a VES in the left ventricle
• This pattern repeats continuously (ping-pong theory)
• On the ECG, QRS complexes rotate
• In the frontal plane in two directions (180°)
• The mechanism is early afterdepolarization
  
  
• Bidirectional Ventricular Tachycardia occurs
• Most commonly in digoxin toxicity
• The second most common cause is Catecholaminergic Polymorphic VT
• Andersen-Tawil Syndrome
• Metastatic heart involvement
• Poisoning by plants of the genus Aconite (Aconite poisoning)
• Bidirectional Ventricular Tachycardia is not ventricular bigeminy
• In ventricular bigeminy, sinus rhythm alternates with ventricular extrasystole in a 1:1 ratio
• In bidirectional ventricular tachycardia, 2 ventricular extrasystoles alternate in a 1:1 ratio

Bidirectional Ventricular Tachycardia

• Frequency: 130/min.
• All QRS complexes are wide > 0.12s
• Because they originate from the ventricles
• Cardiac axis shifts approximately 180° with each beat
• No P waves are present before the QRS complexes
• The tachycardia occurred during physical exertion and the patient was not taking digoxin
• This is catecholaminergic polymorphic ventricular tachycardia

Bidirectional Ventricular Tachycardia

• Heart Rate: 130/min.
• Wide QRS complexes (> 0.12s)
• Heart Axis shifts approximately 180° (best observed on continuous lead II)
• The patient was digitally intoxicated
• This is why catecholaminergic polymorphic ventricular tachycardia is not present on this ECG