Effect of simultaneous heart-lung transplantation on heart allograft with special reference to coronany artery

Heart-lung transplant recipients are considered to suffer significantly less cardiac rejection than those receiving only heart transolants. The present study attempted to score for the degree of the arterial wall thickness to know whether oresence of the lung could suppress an accelearted coronary artetiosclerosis in en bloc heterotopic heart-lung allogtafts. Fischer to Lewis allografts were divided into two group. One consisted of eight rats without treatment (untreated group) and the other consisted of 31 rats treated with Cyclosporin A, 10mg/kg, daily for twenty days agter surgery (treated group). The untreated group was divided into two subgroup , heart and heart-lung allograft, and the treated group into four subgroups, heart allograft killed on day 30, heart-lung allograft killed on day 30, heart allograft killed on 60 and heart-lung allograft killed on day 60. The surgical technique for hetertopic intra-abdominal heart and heart-lung transplantation was a modification of the Ono and Lindsey and Lee procedures, respectively. Rejection was assessed in incremental steps from 0.5 to 3.0 accorind to Lurie classification. The degree of the donor coronary arterial intimal thickness (intralumninal stenotic rate, ISR) was ecaluated bu the following formula : ISR＝100－L/(I＋M＋L) X100 (L : intraluminal area, M : medial area, I : intimal area). In the untreated group, graft survival in the heart allograft was 14.3±2.9days, whereas the heart-lung allograft showed a statistically significant prolongation in cardiac survival with a mean survival-time of 25.5±5.4days. In the treated group, all grafts survived during the scheduled date of killing after surgery. The histologic studies showed more advanced rejection of the heart in the heart-only transplant groups, as compared with the heart-lung transplanted group, while the rejection grade score in the group with heart or heart-lung transplantation during the 30 day period was lower than those of the 60 day period. The intraluminal stenotic rate in the group with heart-lung transplants was slightly lower than in the group woth heart-only transplants. In addition, the longer the transplantation period was, the more servere the intraluminal stenotic rate was in the heart-only and the heart-lung transplants. This study showed that the presence of the lung in heart-lung allografts provides for prolongation of cardiac survival and suppresses the degree of the coronary arteriosclerosis.