An experimental technique for heart-lung transplantation in subprimate models

The success of heart-lung transplant experiments in subprimate models has been limited because most techniques include total pulmonary denervation, which causes respiratory problems, blood loss, and subsequent death. Using 20 subprimates (12 domestic swine and 8 mongrel dogs), we tested a heterotopic heart-single lung transplant method intended to preserve unilateral pulmonary innervation and to reduce blood loss. After native right pneumonectomy, the donor heart and right lung were transplanted en bloc. Anastomotic sites included the right primary bronchus, the superior vena cava, and the aorta. Selective left bronchial intubation and partial occlusion techniques eliminated the need for cardiopulmonary bypass and mediastinal dissection. All 10 recipient animals survived the operation, and the need for blood transfusions was minimal (1.1 +/- 0.7 [mean +/- SD] units/procedure). Donor and native lung function, assessed by selective left atrial blood gases, were similar: mean PO(2) was 229 +/- 31 mmHg and 180 +/- 25 mmHg, respectively; and mean PCO(2), 36 +/- 13 mmHg and 38+/-2 mmHg, respectively. Nine recipients were weaned from mechanical ventilation with a mean PCO(2) of 38+/-4 mmHg. Preserving unilateral pulmonary innervation allows normal respiration, and minimizing blood loss increases operative survival. Our method of heterotopic heart-single lung transplantation is reliable and could provide a functional heart-lung allograft for conducting future experimental studies of heart-lung transplantation.