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Input Multiplicity

-investigating atypical tachycardias-

Patient presentation

  • 49 year old female

  • recurrent palpitations

  • documented tachycardia on ECG

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Differential diagnosis

  • AVNRT (atypical)

  • AVRT

  • Junctional tachycardia

  • Atrial tachycardia

Baseline ECG/EGM

  • AH: 68

  • HV: 46

  • CL: 950

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Retrograde incremental pacing

  • Eccentric retrograde atrial activation (earliest CS 5,6)

  • Decremental VA conduction

  • VA wenckebach at 450ms

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Retrograde paced extras

  • MIdline (CS 9,10 decremental VA conduction

  • No retrograde jumps

  • VERP 350ms

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Antegrade paced extras

  • No evidence of pre-excitation

  • Expected AH lengthening

  • No jumps/no tachycardia

  • Atrial ERP 310ms

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Tachycardia

  • initiated by atrial paced doubles with AH decrementation

  • Narrow complex tachycardia

  • TCL 412ms

  • VA interval 260ms

  • eccentric atrial activation (CS 5,6)

  • terminated with a V (only junctional tach ruled out)

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Diagnostic manoeuvres in tachycardia

  • No atrial advancement during HIS synchronous VPBs
    (nothing ruled out)

  • No change in VA interval during narrow tachycardia verse LBBB aberrancy
    (left sided accessory pathway/AVRT ruled out)

  • Unable to entrain the atrium from the ventricle 
    (AVRT ruled out)

  • Early APB advances immediate HIS and terminating tachycardia
    (ATc verse atypical AVNRT)

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Proceed to map earliest atrial activation

sa

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Post ablation testing

- tachycardia 2 induction -

  • Induced with ventricular incremental pacing

  • Change in atrial activaton pattern from tachycardia 1 (now earliest CS 9,10)

  • TCL 368ms

  • VA interval 236ms

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2nd tachycardia mapped to traditional slow pathway region

  • No further tachycardia induced after slow pathway ablation

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Slow pathway location (s)

  • Predominantly involves a right inferior extension (RIE)

  • Less commonly can have a 

- left inferior extension (LIE) (<5%) or​

- Infero-lateral LA extension (IL-LA) (~1%)

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References

  • Nawata, H. et al (1998). Heterogenity of anteograde fast-pathway and retrograde slow-pathway conduction patterns in patients with the fast-slow form of atrioventricular reentrant tachycardia” Electrophysiologic and electrocardiographic considerations. JACC 32 (6), 1731-1740
     

  • Stavrakis, S., et al (2018). Slow/fast atrioventricular nodal reentrant tachycardia using the inferolateral left atrial slow pathway. Circulation: Arrhythmia and electrophysiology, 11 (9)

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