Ventricular Rate During Atrial Fibrillation Before and After Slow-Pathway Ablation

Introduction: The surface EKG of typical atrioventricular nodal reentrant tachycardia (AVNRT) shows simultaneous ventricular-atrial (RP) activation with pseudo R’ in V1 and typical heart rates ranging from 150-220/min. Slower rates are suspicious for junctional tachycardia (JT). However, occasionally we encounter typical AVNRT with slow ventricular rates. We describe a series of typical AVNRT cases with heart rates under 110/min. Methods: A total of 1972 patients with AVNRT who underwent slow pathway ablation were analyzed. Typical AVNRT was diagnosed when; 1) evidence of dual atrioventricular nodal conduction, 2) tachycardia initiation by atrial drive train with A-H-A response, 3) septal ventriculoatrial (VA) time < 70 ms, and 4) ventricular-atrial-ventricular (V-A-V) response to ventricular overdrive (VOD) pacing with post pacing interval-tachycardia cycle length (PPI-TCL) > 115ms. JT was excluded by either termination or advancement of tachycardia by atrial extrastimuli (AES) or atrial overdrive (AOD) pacing. Results: We found 11 patients (Age 20-78 years old, 6 female) who met the above-mentioned criteria. The TCL ranged from 560ms to 782ms. Except for one patient showing tachycardia termination, all patients demonstrated a V-A-V response and PPI-TCL over 115ms with VOD. AES or AOD pacing successfully excluded JT by either advancing the tachycardia in 10 patients or by tachycardia termination in one patient. Slow pathway was successfully ablated, and tachycardia was not inducible in all patients. Conclusions: This case series describes patients with typical AVNRT with slow ventricular rate (less than 110/min) who may mimic JT. We emphasize the importance of using pacing maneuvers to exclude JT.

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Abstract 738: Role of the Pulmonary Veins in Experimental Paradigms of Remodeling- Basic Science Associated Atrial Fibrillation

Circulation ◽

10.1161/circ.116.suppl_16.ii_139-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Masao Sakabe ◽

Kristina Lemola ◽

Katsuyoshi Chiba ◽

Grigorios Katsouras ◽

Akiko Shiroshita-Takeshita ◽

...

Keyword(s):

Atrial Fibrillation ◽

Pulmonary Veins ◽

Rate Adaptation ◽

Ventricular Rate ◽

Atrial Remodeling ◽

List Type ◽

Ablation Therapy ◽

Before And After ◽

The Mean

Background : Pulmonary vein (PV) activity is crucial in some forms of clinical atrial fibrillation (AF), particularly paroxysmal lone AF. The precise importance of PVs in AF associated with structural heart disease is less clear. Some evidence suggests that PVs may be important for AF in experimentally-remodeled atrial substrates, e.g. atrial-tachycardia remodeling (ATR) and congestive heart failure (CHF)-induced structural remodeling, but contradictory findings also exist. This study assessed the role of PVs in canine remodeling-associated AF by evaluating the changes induced by PV-LA disconnection via encircling epicardial ablation. Methods: AF was induced before and after complete isolation of all PVs in dogs with: ATR induced by atrial tachypacing (400 bpm x 1 wk; with AV block and 80 bpm ventricular pacing to control ventricular rate, n=5); and CHF induced by ventricular tachypacing (VTP, 240 bpm x 2 wks, n=7). Electrophysiological measurements and AF mapping with 240 unipolar atrial electro-grams in both atria and all PVs were also obtained before and after PV isolation. Results ATR reduced atrial ERPs and ERP rate adaptation. The shortest AF cycle length (AFCL) in each ATR dog was recorded from PVs (mean 84±3 ms), but the mean AFCL in each of the PVs (range 97–103 ms) was not different from the mean AFCL at LA sites (98 –103 ms). PV ablation did not affect AF duration in ATR dogs (mean 284±265 pre- vs. 304±225 s post-ablation, P=NS), nor did it significantly alter RA or LA AFCL. In CHF dogs, ERPs and ERP rate adaptation were preserved. The shortest AFCL was recorded in PVs in 2 dogs (108,112 ms) and in the left side of Bachmann’s bundle in 3 (97–117 ms). PV ablation failed to alter AF duration in CHF dogs (mean 778±203 pre- vs. 644±206 s post-ablation), and increased AFCL in RA and LA slightly (10 –15%) but not significantly. Conclusions : Uncoupling of the PVs from the LA fails to significantly affect the AF substrate in 2 clinically-relevant animal paradigms of AF-promoting atrial remodeling. These findings suggest that in the presence of a favorable atrial substrate for AF the PVs are not needed for AF maintenance, and are consistent with clinical observations that complete PV isolation may not be essential for effective ablation therapy of all groups of AF patients.

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