Characteristic P Wave Morphology in Patients Undergoing the Atrial Compartment Operation for Chronic Atrial Fibrillation with Mitral Valve Disease

The P wave in the surface ECG represents atrial electrical activation and may be altered in certain pathological conditions. Atrial compartment operation has been used to convert chronic AF to sinus rhythm. However, this procedure may result in changes of impulse conduction in various atrial compartments and alters the P wave morphology. This study sought to elucidate the P wave changes after the atrial compartment operation for AF. Fifteen patients undergoing the atrial compartment operation for chronic AF were studied. In the operation, the atrium was divided into three compartments, namely the left atrium, the atrial septum including sinus and AV nodes, and the right atrial compartment. The anatomic connection between adjacent compartments were preserved at the posterior lower margin of incisions. The surface lead P waves were correlated with intracardiac recording and stimulation in various atrial compartments. Fifteen age- and sex-matched control patients without structural heart diseases were compared. The results showed that patients undergoing the atrial compartment operation had a prolonged P wave duration (190 +/- 27 vs 95+ /- 14 ms, P 0.05). Although the patients undergoing atrial compartment operation had a larger left atrial size, their P wave amplitude was smaller(1.0 +/- 0.3 vs 1.3 +/- 0.3 mm, P 0.05). Alteration in P wave morphology was seen in 14 patients. All the P waves showed a biphasic configuration with an initial positive and a terminal slurred negative deflection in leads II, III, and aVF The terminal components represented the activation of right atrial appendage in 5 patients, the left atrium in 1, and the combined activation of right atrial appendage and the left atrium in 8 patients. The P wave morphology suggested that activation of both the right atrial appendage and the left atrial compartments proceeded in a caudocranial direction as a result of the atrial incisions. In conclusion , atrial compartment operation altered the conduction time and direction in the atria and resulted in characteristic P wave changes