Long-term daily study of blood volume in cardiac autotransplanted dogs

Cardiac transplantation is followed by the interruption of afferent nerves to the heart. Knowing that some of the afferent nerves are responsible for the homeostasis of the blood volume, we undertook a serial and long-term study of the blood volume in 25 dogs with denervated hearts. The animals were autotransplanted in order to eliminate repercussions linked to rejection and to its treatment. To discern the effects of surgery and of extracorporeal circulation from those of denervation, a group of 11 control dogs was operated upon and subjected to a period of extracorporeal circulation. In both groups, serial and long-term studies of blood volume were carried out daily with 131I-labeled albumin. Analysis of the results demonstrated that in the hours following surgery, blood volume is significantly decreased by 11% in the control group and by 22% in group 2. By the 5th postoperative day, the blood volume had increased gradually to attain normal values in both groups. At the 2nd postoperative week, the total blood volume remained normal in the control group, whereas blood volume had increased by 5.7% in the autotransplanted dogs, this being due to a 38% increase of the plasmatic phase. This increment persisted from the 14th to the 42nd postoperative day and attained 7.4%. Our conclusion is that the variations in blood volume during the 1st postoperative week in the autotransplanted heart are inherent in surgery and in extracorporeal circulation. Afterwards, the hypervolemia shown in the transplanted dogs is secondary to cardiac denervation.