In a patient with a transplanted heart which of these are the reasons for increased cardiac output during exercise

Cardiac transplantation results in total denervation of the donor's heart, including the donor sinus node, which usually controls heart rate after transplantation. Denervation causes an increase in basal heart rate due to parasympathetic sectioning (normally parasympathetic tone is greater than sympathetic tone on the heart). Further increase in heart rate during exercise is dependent primarily on increase in plasma catecholamine concentration, e.g. from the adrenal medulla.