[Effect of cardiac rejection on blood volume]

The variations of blood volume after autotransplantation have been documented recently by our group. Since, in the homotransplanted heart, acute rejection affects cardiac function we felt that the blood volume variations might be different than that of the autotransplants. In thirty-one immunosuppressed dogs with an orthotopic homotransplanted heart, daily assessments of blood volume with iodine 131 tagged albumin was carried out from preoperative period (control) until death from acute rejection. In the immediate postoperative period there was a significant fall of 21% of the blood volume caused by a 20% fall of plasmatic volume and of a 23% fall in erythrocyte volume. From the second to the fifth postoperative day in spite of persistence of a low erythrocyte volume the blood volume progressed to normal due to a compensatory increase of the plasmatic volume. In the terminal phase of rejection there was a 32% increase of the plasmatic volume leading to an 8% increase of the total blood volume.