Results
We identified 5 patients from Cleveland Clinic and 9 patients from the
University of California, San Francisco, who had very slow (110 bpm or
less) typical AVNRT. Three additional patients were excluded because
they did not undergo AOD or AES pacing maneuvers as noted in the Methods
section, although tachycardia was no longer inducible after their slow
pathway ablation. Therefore, a total of 11 patients were included in
this analysis. Patient characteristics and electrophysiologic study data
are shown in Table 1. Ages ranged from 20 to 78 years. There
were six females and five males. One patient was undergoing a 4th
ablation (Case 4), and two patients had their 2nd ablations (Case 7 and
9). All other patients were undergoing their initial ablation. The
tachycardia cycle length ranged from 560ms to 782ms. Septal VA times
were all within 70ms. All patients except for one demonstrated V-A-V
response by VOD, which showed PPI-TCL over 115ms. VOD reproducibly
terminated tachycardia in one patient (Case 8), and thus VOD could not
be obtained.
We delivered AOD or AES to distinguish this tachycardia from JT.
Advancement of the tachycardia was recognized by overdrive pacing from
at least one location of the atrium (usually from the coronary sinus
ostium) in 5 patients. Termination of tachycardia was recognized in one
patient by overdrive atrial pacing (Case 4). With regards to the
response to AES, 6 patients showed an A-H-A response, while one patient
(Case 1) showed A-H-H-A response with the advancement of the
tachycardia, likely due to a double ventricular response.
All patients underwent successful slow pathway ablation rendering their
tachycardia not inducible after ablation.