Objectives: Supraventricular arrhythmias are one of the most common and fatal sequelae of the Fontan operation. P wave triggered signal averaged electrocardiography was performed in patients undergoing the Fontan operation to evaluate the presence of atrial degeneration, and to clarify which factors affected the development of atrial arrhythmias.
Methods: P wave triggered signal averaged electrocardiography was recorded in 14 patients after the Fontan-type operation (conventional atriopulmonary connection in 5 and total cavopulmonary connection in 9) and 15 healthy controls. The duration and area of the filtered P wave, and the signal magnitudes (M20, M30) at 20 Hz and 30 Hz obtained from the frequency domain analysis of the P wave (M20, M30) were evaluated and compared with the hemodynamic data.
Results: The duration and area of the filtered P wave, M20 and M30 in patients after atriopulmonary connection were significantly greater than in those after total cavopulmonary connection and the control subjects (p < 0.05). M20 was significantly greater in patients after total cavopulmonary connection than in the control subjects. Right atrial volume in patients after atriopulmonary connection was significantly (p < 0.001) larger than in patients after total cavopulmonary connection (p < 0.05). There were no significant differences in other indices including atrial pressure between the two groups.
Conclusions: Our results suggest that the substrate for atrial arrhythmias such as atrial myocardial degeneration and fibrosis is frequently present in patients after the Fontan operation, especially after atriopulmonary connection. Thus, the enlarged right atrium may be involved in the presence of a substrate for atrial arrhythmias. The developmental risk for late atrial arrhythmias seems to be present even in patients after total cavopulmonary connection.