Ventricular tachycardia as a consequence of triggered activity

Area of Science:

• Cardiology
• Electrophysiology
• Pharmacology

Background:

• Ventricular tachycardia (VT) can arise from triggered activity, a mechanism involving early or delayed afterdepolarizations.
• Certain medications like hydrochlorothiazide and hydroxyzine, as well as catecholaminergic surges, can precipitate afterdepolarizations.
• Outflow tract (OT) tachycardia is a specific type of VT often associated with delayed afterdepolarizations and uniquely responsive to adenosine.

Observation:

• A case of triggered outflow tract tachycardia is presented.
• The patient's condition was potentially influenced by medications causing QT prolongation and early afterdepolarizations.
• Intravenous amiodarone was administered, possibly effective due to its antiadrenergic properties.

Findings:

• Triggered activity is an under-recognized mechanism of VT.
• Delayed afterdepolarizations are implicated in outflow tract tachycardia.
• The case suggests amiodarone's potential role in managing triggered OT tachycardia, though other agents might be considered.

Implications:

• Understanding the specific VT mechanism, such as triggered activity, is crucial for selecting optimal treatment.
• In cases of acquired long QT syndrome, therapies that do not prolong repolarization, like magnesium or specific beta-blockers, may be more appropriate.
• This case underscores the importance of tailored therapeutic approaches for complex VT presentations.