Tach me if you can
-mistaken identity in SVT-
Patient presentation
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64 year old female
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episodic palpitations for last few years
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previous admissions for incressant, non sustained SVT
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stop/start bursts suggestive of ATc
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Documented tachycardiast
Differential diagnosis
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AVNRT (atypical)
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AVRT
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Junctional tachycardia
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Atrial tachycardia
P wave morphology
Tachycardia onset
Tachycardia offset
Baseline ECG/EGM
Retrograde pacing
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Decremental, midline VA conduction
Tachycardia - onsets
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initiated by atrial ectopic
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initiated by ventricular ectopic
?2 for 1 phenomenon
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junctional verse 2:1
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same phenomenon inducing tachycardia
Tachycardia termination
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terminating with V consistently
Tachycardia characteristics
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Long RP tachycardia with midline activation
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TCL 450ms
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VA interval 184ms
Atrial pacing
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Unable to perform any diagnostic baseline manoeuvres without inducing SVT
Tachycardia termination with early APB
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Does not help differentiate AVNRT from ATc
Early APB showing linked VAs
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demonstrates that VA conduction is involved in the circuit, consistent with AVNRT
Post slow pathway ablation
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VA dissociation. No further inducible tachycardia
References
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Kistler et al., (2005). Focal atrial tachycardia from the ostium of the coronary sinus. American college of Cardiology 45(9), 1488-1493
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Kistler, P. et al., (2021). P-Wave Morphology in Focal Atrial Tachycardia: An Updated Algorithm to Predict Site of Origin. Clinical Electrophysiology, 7 (12), 1547-1556
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Mandharam, V.R. & Lokhandwala, Y.Y. (2022). Last entrainment sequence: the last work in perinodal atrial tachycardia diagnosis? Clinical electrophysiology, 8 (10), 1301-1303
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Veenhuyzen, G.D. & Quinn, F.R (2008). Principles of Entrainment: Diagnostic Utility for Supraventricular Tachycardia. Indian pacing and electrophysiology journal. 1;8 (1), 51-65