Introduction: Surface ECG is a useful tool to guide mapping of
focal atrial tachycardia (AT).We thought to construct an algorithm,
based on paced P wave templates from different anatomical sites in both
atria in patients with normal hearts. Methods: We prospectively
enrolled consecutive patients who underwent electrophysiology study,
having no heart disease. Atrial pacing was carried out at different
anatomical sites in both atria. Paced P wave morphology (PWM) and
duration (PWD) were assessed. P wave morphology was classified into:
positive, negative, biphasic (+/- or -/+) and isoelectric. A proposed
algorithm was generated from the constructed templates of each pacing
site. Results: Sixty-four patients (25 males) were enrolled.
Mean age was 37 ± 13 years. Atrial pacing was performed in 61 patients
(95%) at the right atrium and in 15 patients (23%) at the left atrium.
A neg/iso P wave in V1, a pos/iso P wave in AVL and lead I identified
right atrial pacing sites (p=0.01, p=0.02 and p=0.02, respectively).
Negative P wave in lead aVL identified left pulmonary veins when
compared to right pulmonary veins (P=0.03). PWD was significantly longer
when pacing from lateral tricuspid annulus (TA) as compared to medial TA
(136 ± 12ms vs. 99 ± 10 ms , P=<0.001) and when pacing from
the left superior pulmonary vein as compared to the right superior
pulmonary vein (152 ± 12 ms vs. 135± 10 ms, (P=0.001).
Conclusions: PWM and PWD derived from templates generated
through atrial pacemapping could be used to guide localization of focal