Duration and dispersion of the P wave after the Senning operation.

We studied the duration and dispersion of the P wave in patients after a Senning operation, assessing its value in detecting the risk of atrial tachycardias.We measured the duration and dispersion of the wave in surface 12 lead electrocardiograms obtained from 18 patients with sinus rhythm, having a mean age of 12.8 years, with 13 being males and 5 females, who had undergone a Senning operation, comparing the values obtained in 35 age and gender-matched healthy people. The patients had undergone repair at a mean age of 13.4 months, and had a mean duration of follow-up of 12.8 years after the procedure. We also made 24 hour Holter recordings.The maximal duration of the P wave, at a mean of 129.3 milliseconds, and dispersion with a mean of 78 milliseconds, were both significantly increased in the patients compared with their controls, the mean values for the normal subjects being 103.7 and 54 milliseconds. Supraventricular tachycardia was detected in 1 of 3 patients with dispersion greater than 100 milliseconds, and in 2 of 15 patients (13%) with dispersion less than 100 milliseconds as measured from the Holter recordings (p > 0.05).Thus, the maximum duration and dispersion of the P wave were increased in patients after a Senning operation, but we were unable to establish any relationship between these measurements and atrial tachycardias as observed using Holter monitoring.