PMC3775323_01
Baseline 12-lead ECG at the beginning of the electrophysiology study showing intermittent pre-excitation. A positive/negative QRS in V1 and R>S in lead III suggested a right superior paraseptal location.
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F1
Her ECG (Figure 1) suggested a right superior paraseptal accessory pathway (AP).
Induction of atrio-ventricular reciprocating tachycardia with a single extrastimulus from the atrium. Earliest atrial activation can be seen at the proximal pair of electrodes at the His catheter, which shows continuous activity and near absence of His electrogram. HBEP, HBEM, HBED: His catheter from proximal to distal. ORB: decapolar catheter placed in the coronary sinus. RVA: right ventricular apex catheter.
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F2
During tachycardia, the HV interval was 51 ms, and earliest atrial activation was recorded in the superior paraseptal region (Figure 2), a similar pattern to that observed during ventricular pacing.
Wenckebach-type AV block caused by pressure with the ablation catheter, showed at a sweep speed of 67 mm/sec. ABL: ablation catheter. RVA: right ventricular apex catheter.
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F3
AV block (Figure 3). A His catheter recording confirmed this block to be supra-hisian (Figure 4); it resolved after a few minutes but was reproducible.
A His catheter recording confirms a supra-hisian block. Note the absence of a His potential following the atrial activity after the third QRS complex.
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F4
AV block (Figure 3). A His catheter recording confirmed this block to be supra-hisian (Figure 4); it resolved after a few minutes but was reproducible.