A PULMONARY XENOGRAFT MODEL 
FOR MICROCIRCULATOR^^ OBSERVATION 
W. A. Cook. P, B. Spelller, S. K. Slausner, S. B. P. Sinha. Y. Kikkawa and F. J. Veith' 
Several pulmonary xenograft models have been in- 
vestigated to determine their usefulness in microcircu- 
latory study of hyperacute rejection. Pig, sheep and 
cat lungs were transplanted to the dog. Our microcir- 
culatory observations were made with an incident light, 
dark-field technique employing a metallurgical micro- 
scope. This allows observation of the pulmonary vascu- 
lature through the surface of the intact lung. The most 
suitable of these models was a cat-to-dog pulmonary 
xenograft utilizing both cat lungs as a lung block 
grafted into the left thorax of the dog. 
INTRODUCTION 
Xenograft models should have ready avail- 
ability of the animal donor and recipient and 
ease of technical preparation. A cat-to-dog lung 
graft model, which we have recently developed 
and which consists of a transplant of both cat 
lungs into the left hemithorax of a dog, meets 
these requirements. 
METHODS 
The donor cats were anesthetized with in- 
traperitoneal pentobarbital and their tracheas 
intubated via a tracheostomy. The animals were 
placed on a volume controlled ventilator, and 
their chest opened by median sternotomy. The 
main pulmonary artery was dissected free to 
its root. The superior and inferior venae cavae 
were ligated. Rapidly thereafter, the trachea 
was clamped and obliquely transected, and the 
heart and both lungs excised as a block after 
dividing the aorta. The ventricles were removed 
from the lung block by incising the atria cir- 
cumferentially just proximal to the atrio- 
ventricular junction and by transecting the 
main pulmonary artery just distal to the pul- 
monary valve. The left atrial appendage and 
excess portions of the right atrium were excised 
so that a circular cuff of left atrium containing 
the orifices of all the pulmonary veins was left 
* Albert Einstein College of Medicine, and Montefiore Hospital, 
New York, New York. 
attached to the lung block. A cannula was tied 
loosely in the main pulmonary artery, and all 
cat blood was removed from the lung block by 
perfusing the vascular tree with chilled (4°c) 
Ringer's lactate solution at a pressure of 15 cm 
of HoO until the effluent coming from the pul- 
monary veins was clear. 
While this was being done, the recipient dog, 
which was also anesthetized with pentobarbital, 
was given 2 mg/kg of heparin, and ventilated 
with a volume respirator, and a left pneumonec- 
tomy was performed. The left pulmonary ar- 
tery, the left mainstem bronchus, and a cuff of 
left atrium containing the orifices of the pul- 
monary veins to the left lung were occluded 
with atraumatic clamps. Care was taken to pre- 
serve as much of these structures as possible. 
The cat lung block was then placed in the 
left hemithorax of the recipient dog (Fig. 1). 
The lung block was held anteriorly and the 
posterior wall of its left atrial cuff was sutured 
to the recipient left atrial cuff with a continu- 
ous everting 6-0 silk mattress suture which was 
reinforced by an over-and-over suture of 6-0 
silk. The obliquely cut trachea of the cat lung 
block was then sutured to the end of the dog 
left mainstem bronchus with a continuous su- 
ture of 4-0 dacron, and the bronchial clamp 
was removed so that the lung block was again 
ventilated. The lung block was then held pos- 
teriorly and the anterior wall of the left atrial 
anastomosis completed with continuous evert- 
ing and over-and-over sutures. The main pul- 
monary artery of the cat was then anastomosed 
to the left pulmonary artery of the dog with a 
continuous over-and-over suture of 6-0 silk, 
and the vascular clamps removed. The cat lungs 
were without ventilation for from 25-35 min- 
utes and without circulation for from 50-60 
minutes. 
Of primary importance to our work is the 
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