The objectives of this research are to extend the role of surgery in the treatment of atrial dysrhythmias. First, the surgical anatomy and physiology of the atria will be determined by various surgical procedures. For example, the following will be done: excision or exclusion of the SA node from the remainder of the atrium; destruction of the atrium adjacent to the coronary sinus, the sequential division of the internodal tracts; division of Bachmann's bundle and excision of the atrial septum. The feasibility will be explored of substituting coronary sinus or AV nodal rhythm for defective SA nodal rhythm. The production of atrial rhythm disturbance will be done to determine whether of not any of the experimental surgical procedures can be employed for clinical use.