P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Surgery

Background:

• Ectopic atrial rhythms can complicate post-cardiac surgery recovery.
• Accurate localization of ectopic atrial rhythm origins is crucial for effective management.
• Current methods for localizing these rhythms have shown variable reliability.

Purpose of the Study:

• To investigate the utility of P wave characteristics and P-R interval in localizing ectopic atrial rhythms.
• To assess the impact of pacing from various atrial sites on P wave morphology and polarity.
• To evaluate the reliability of established criteria for ectopic atrial rhythm origin determination.

Main Methods:

• Threshold bipolar pacing was utilized in 69 patients following open-heart surgery.
• Pacing was performed from 12 distinct atrial sites using temporary implanted electrodes.
• P wave polarity, morphology, and P-R intervals were systematically recorded and analyzed.

Main Results:

• Specific P wave patterns in Lead I and V1 were observed only with left atrial pacing near pulmonary veins or coronary sinus.
• P wave polarity and morphology were otherwise unhelpful for impulse origin localization.
• Pacing stimulus to P wave intervals varied significantly (10-54 msec), rendering the P-R interval unreliable for localization.

Conclusions:

• P wave polarity, morphology, and P-R interval provide limited value in ascertaining the origin of ectopic atrial rhythms in humans.
• Previously published criteria for localizing ectopic atrial rhythms were demonstrated to be unreliable in this study.
• Further research is needed to develop more accurate methods for identifying the source of ectopic atrial rhythms.