THEODORE I. MALININ 
367 
monkeys apparently resume functioning after 
about one hour of normothermic ischemia, as do 
porcine kidneys. 
In contrast to kidney, canine liver is ex- 
tremely sensitive to ischemia, and usually be- 
comes unsuitable for transplantation following 
20-30 minutes of normothermic ischemia.^^-^^ 
Primate liver is more resistant to ischemia, 
recovering after being subjected to ischemia 
for over an hour.^^ This suggests basic physio- 
logic difference between canine and primate 
livers. 
Morphological and ultrastructural changes 
are observed in the heart following even brief 
ischemia periods. After 8-12 minutes of total 
ischemia, De Gasperis et al. noted occasional 
mitrochondrial changes, while after 25-30 min- 
utes they reported loss of cristae with clear- 
ing of the matrix of the mitrochondria, as well 
j as loss of glycogen.2* Forty-five to 50 minutes 
of ischemia led to mitrochondrial changes con- 
sisting of irregularity of shape, reduction in size 
with very close cristae, loss of matrix, trans- 
verse tubular dilation, indentation of the nu- 
clear surface and loss of glycogen. The ischemic 
myocardium of dogs was studied by Denker et 
al.2^ who noted that critical membranous struc- 
tures were altered as early as 20 minutes after 
the ligation of a coronary artery. However, 
these ultrastructural changes are apparently re- 
versible, as their presence does not appear to 
prevent perfused hearts from contracting.^^ On 
the other hand, the lack of such changes did 
not assure the survival of transplants, as was 
demonstrated by Trunkey and co-workers.^^ 
This brings up the question of the full restora- 
tion of the organ function following transplan- 
tation. In transplanted kidneys, a decreased or 
even temporarily suspended function is still 
compatible with life. With hearts and lungs this 
I is not the case, as even a brief significant im- 
pairment of function will lead to the death of the 
host. Any transplantation procedure with these 
organs must therefore provide for the immedi- 
ate resumption of function from the implanta- 
tion onwards. 
Normothermic ischemic tolerances of lungs 
depend on whether the lungs are collapsed, in- 
flated or ventilated. It was shown in experiments 
performed on dogs that the animals survived 
after one-half hour of ischemia with the lungs 
collapsed, after two hours of ischemia with the 
lungs ventilated, and after three hours when 
the lungs were inflated.^'^ These data correlate 
well with previously-suggested safe upper limit 
of unmodified pulmonary ischemia of two 
hours.28 
PRESERVATION OF ORGANS 
BY HYPOTHERMIA 
The life span of an isolated organ can be 
increased several fold by simple cooling. Cool- 
ing is achieved either by exposing the organ 
to low ambient temperature or by flushing the 
organ with a solution of a desired temperature. 
For primate kidney preservation of several 
hours, the best results, as judged by their func- 
tion following implantation, are obtained by 
simple cooling. Irrigation with small quantities 
of cold electrolyte solution produces some tubu- 
lar damage, but has the added advantage of 
rapidly cooling the organ. Canine kidneys, when 
reimplanted into animals after six hours of 
storage at 4°C, will support the animal's life 
in virtually all cases. Kidneys stored 24 hours 
at the same temperature will support life in 
about 50% of animals. Only 25% of animals 
will survive after being transplanted with kid- 
neys stored for 48 hours. Function does not re- 
turn to kidneys transplanted after 72-96 hours 
of storage. 2^ 
Rhesus monkey liver has been successfully 
preserved by simple cooling for 3.5-5 hours.^^ 
Dog liver fails to function following two hours 
of simple hypothermia. 
Hsrpothermia alone does not permit lung stor- 
age beyond a few hours. However, an increased 
storage time has been reported with hypother- 
mia and hyperbaria. Garzon and associates 
stored lung grafts at 4°C under oxygen at 
2ATA for 24 hours. The pulmonary vasculature 
was flushed with lactated Ringer's solution. 
Seven animals were reimplanted with lungs pre- 
served in this manner. These survived for a 
mean period of 21 months. There were no sig- 
nificant changes in the minute ventilation and 
oxygen uptake of these lungs, indicating that 
preserved reimplanted lungs maintained ade- 
quate functional capacity. However, the func- 
.1 
