SINUS ARRHYTHMIA IN DOGS AFTER CARDIAC TRANSPLANTATION

The recurrence of sinus arrhythmia after cardiac transplantation was studied in 17 dogs previously subjected to cardiac autotransplantation and in 2 dogs after homotransplantation. Sinus arrhythmia was demonstrated in 13 animals between 2 1 2 and 20 months after cardiac autotransplantation and in 1 dog 140 days after cardiac homotransplantation. In all animals sinus arrhythmia recurred after parasympathetic reinnervation of the heart. There was a variable lag between the first demonstration of parasympathetic reinnervation and the recurrence of sinus arrhythmia. Sinus arrhythmia was abolished after efferent parasympathetic blockade with intravenously administered atropine but was not affected by beta adrenergic blockade with propranolol. The recurrence of sinus arrhythmia after cardiac transplantation signifies the occurrence of parasympathetic reinnervation of the heart. Absence of sinus arrhythmia, however, does not exclude the presence of such reinnervation. © 1969.