"Double Capture" - a technique to differentiate narrow complex Supraventricular Tachycardias

Area of Science:

• Electrophysiology
• Cardiac Arrhythmia Research
• Diagnostic Maneuvers

Background:

• Distinguishing between atrial tachycardia (AT), atrio-ventricular nodal re-entrant tachycardia (AVNRT), and orthodromic re-entrant tachycardia (ORT) in narrow complex supraventricular tachycardia (SVT) is crucial in the electrophysiology (EP) laboratory.
• Current diagnostic maneuvers often require combination due to the limited reliability of single tests.

Purpose of the Study:

• To evaluate the efficacy of a single His-synchronous simultaneous extra-stimulus in the atrium and ventricle, termed "Double Capture," in reliably differentiating narrow complex SVT mechanisms.

Main Methods:

• A retrospective analysis of 44 patients undergoing electrophysiology studies for narrow complex SVTs was conducted.
• The "Double Capture" maneuver involved delivering simultaneous extra-stimuli to the atrium (A) and ventricle (V) when the His was refractory.
• Intracardiac recordings were analyzed to assess the earliest signal post-maneuver to differentiate arrhythmia mechanisms.

Main Results:

• The "Double Capture" maneuver was successfully achieved in 29 out of 38 eligible patients (76%) with either AVNRT or ORT.
• Reproducible termination of tachycardia upon "Double Capture" was associated with ORT (7 patients).
• A His signal as the first post-stimulus signal with ongoing tachycardia typically indicated AVNRT (20 patients), with two exceptions of ORT.

Conclusions:

• The "Double Capture" maneuver demonstrated a specificity of 78% for confirming AVNRT and 100% for ORT in sustained narrow complex SVT.
• This technique may be particularly useful for confirming bystander pathways or evaluating septal pathways in SVT diagnosis.