Patient Example (Case 4)
Figure 1 shows ECGs during sinus (A) and reentrant arrhythmia
(B) of a patient example (Case 4) who underwent 3 slow pathway ablations
prior to the current study. This patient had been in this incessant
arrhythmia shown in panel B after the 3rd ablation. The surface ECG
showed a very slow junctional type arrhythmia (HR 75/min), and the
patient was significantly symptomatic when in this arrhythmia. The
patient was treated as having a junctional arrhythmia, and beta-blocker
therapy was prescribed, which did not improve her symptom. Due to the
inefficacy of this treatment, the patient was referred for further
possible ablation. Intracardiac studies showed simultaneous VA
activation with septal VA timing of 59ms. VOD showed V-A-V response with
PPI-TCL 177ms (Figure 2). AES delivered during the slow pathway
refractory period (on time with retrograde fast pathway depolarization)
terminated the tachycardia, which proved that slow pathway conduction
was part of the tachycardia mechanism (Figure 3) . AOD delivered
from CS 1-2 successfully entrained the tachycardia. The septal PPI-TCL
confirmed a reentrant mechanism (Figure 4) . After the
successful slow pathway ablation, this tachycardia could never be
inducible, and the patient became asymptomatic.