394 
SURGERY AND TRANSPLANTATION 
Table II. — Causes of Death in an Additional 350 Baboon Kidney Allografts 
Type of Total Thromboses Eejection Other Causes 
Transplant Done No. Percent No. Percent No. Percent 
En Bloc 
One kidney 80 20 25 51 63.75 9 11.25 
Single kidney with irrigation 
of recipient's vessels 120 30 25 75 62.50 15 12.50 
Single kidney with aortic patch 
and irrigation of vessels _ _ 150 33 22 87 58.00 30 20.00 
Total 350 83 213 54 
Table II compares the results of a further 350 
transplants. These were done according to the 
variations on the two main groups as described. 
Where a single kidney was transplanted with 
the attached aorta and inferior vena cava seg- 
ment, results were no worse than in the pre- 
viously described groups where both kidneys 
were transplanted (Table II). The 3% lower 
thrombosis rate is not a significant improve- 
ment ; however, it indicates that there is no def- 
inite advantage in transplanting both kidneys, 
as one kidney with normal function will sustain 
life in the baboon. In both instances, the related 
incidence of thrombosis observed with the varia- 
tions of the single kidney transplant indicate an 
improvement over the previously obtained re- 
sults. The incidence of thrombosis was 25% and 
22% (Table II) . The incidence of rejection rela- 
tive to the decrease in the rate of thrombosis is 
higher in these three groups (Table II) . 
Graft thrombosis, when present in all the re- 
ported groups, was either arterial and venous 
or arterial only. No incidence of solitary venous 
thrombosis and graft clotting was observed. 
This reflects the lack of any technical difficulty 
with the venous anastomosis in either type of 
renal allograft technique. 
The average ischemic time for the en bloc 
transplants was about 42 minutes. In the single 
kidney transplants, including those with an 
aortic patch, the average ischemic time was 
about 24 minutes. These operations were per- 
formed adequately by ten surgeons over a two 
year period. It is apparent, however, that vas- 
cular problems can still present serious difficul- 
ties in the use of baboons in some organ allo- 
grafts. The problems are, however, less than 
those encountered with other primates.^'i^ 
In experimental animals where the donor 
need not be sacrified, the direct arterial trans- 
plantation method and the time saved are ob- 
vious advantages of transplanting single kid- 
neys. 
Where only one kidney was transplanted with 
the 671 bloc method, the results achieved were 
very similar to those obtained when both kid- 
neys were used (Tables I and II) . Single kidneys 
with single vessels would seem, therefore, to 
be the most advantageous for experimental 
transplantation. Therefore, an attempt was 
made to lower the thrombosis by irrigating the 
segments of the recipients' vessels between the 
vascular clamps to wash out any blood which 
might give rise to eventual thrombosis. Possible 
clots were then flushed out by releasing the vas- 
cular clamps before the final suture was tight- 
ened and tied. This was thought necessary be- 
cause the animals were not heparinized for the 
transplant procedure. These precautions slightly 
improved the results. The incidence of thrombo- 
sis in the group was 25% (Table II) as compared 
to 34.1% in the other single kidney transplants 
(Table I). This is an overall improvement of 
9%. 
A further modification lower the incidence of 
graft thrombosis to 22% in the single kidney 
transplants (Table I). This was achieved by 
utilizing an aortic patch to give a wider anasto- 
motic opening. This method was of special value 
in some smaller animals with relatively smaller 
renal vessels. Combined with the described ir- 
rigating procedures, the achieved 22% throm- 
bosis influence (Table II) was satisfactory when 
compared to the previous incidence of 34.1% 
(Table I) . This was an overall improvement of 
12%. 
Cardiac Surgery and Cardiac Transplantation 
The use of the baboon as a subhuman primate 
in experiments necessitating the use of a heart 
