SINGLE LUNG TRANSPLANTATION WITH IMMEDIATE LIGATION 
OF THE OPPOSITE PULMONARY ARTERY IN THE DOG: A 
MODEL FOR ASSESSING THE FUNCTIONAL ADEQUACY OF 
TRANSPLANTED LUNGS 
F. J. Veith, S. B. P. Sinha,* S. S. Siegelman and J. W. C. Hagstrom 
Since single lung transplants in patients will have to 
provide virtually total pulmonary function, it is impor- 
tant that studies on experimental lung transplants be 
performed under analogous functional stresses. We 
found that dogs routinely survive after autotrans- 
plantation or allotransplantation of either lung and im- 
mediate ligation of the opposite pulmonary artery if 
technical errors are avoided and if the arterial anasto- 
mosis of the transplant is made distensible. This can be 
achieved by a variety of techniques. Nine of 16 dogs 
(56%) subjected to autotransplantation of the left lung 
and immediate ligation of the right pulmonary artery 
(RPA) survived from 2 to 45 months. These dogs had 
pulmonary artery pressures, pulmonary vascular resist- 
ances, arterial and venous blood gas values, and lung 
histology comparable to those in normal dogs undergo- 
ing RPA ligation. The only abnormality present on pul- 
monary angiograms was a 25-75% increase in the di- 
ameter of the left pulmonary artery and its major 
branches. This documents the importance of distensibil- 
ity of the large pulmonary arteries in situations requir- 
ing increased pulmonary blood flow and emphasizes the 
importance of making a distensible pulmonary artery 
anastomosis in dog lung transplants charged with carry- 
ing the entire cardiac output. Only 11 of 115 dogs 
(10%) receiving left lung allografts with immediate 
ligation of the RPA lived one to three months. Despite 
intensive immunosuppression with azathioprine, anti- 
lymphocyte serum, and corticosteriods, rejection was a 
major cause of death in these dogs. Thus, a single trans- 
planted canine lung can provide total respiratory and 
vascular function at all times after operation up to 3 
years. The described model supports the feasibility of 
single lung transplantation in patients with pulmonary 
hypertension and provides a method for evaluating im- 
munosuppressive regimens and lung preservation tech- 
niques intended for use in lung transplantation. 
INTRODUCTION** 
Potential lung transplant candidates will 
have severe bilateral pulmonary disease. Ac- 
* Department of Surgery, Montefiore Hospital and Albert Einstein 
College of Medicine, 111 East 210 Street, New York 10467. 
** This work was supported in part by grants from the U.S. 
Public Health Service (HE 11472), the Health Research Council of 
the City of New York, the Manning Foundation and the John A. 
Hartfoi-d Foundation. 
cordingly, any therapeutic lung transplant must 
be able to provide adequate total gas exchange 
while carrying the entire cardiac output at tol- 
erable pulmonary arterial pressures. Since 
there are presently no methods for providing 
assisted gas exchange, the transplanted lung 
must meet these functional requirements from 
the moment of its insertion onward. Because of 
the complexity of bilateral lung transplantation 
procedures, it would be advantageous if a single 
lung graft could satisfy these needs. 
To be of maximal predictive value for human 
lung transplantation, studies of experimental 
lung transplants should be performed under 
functional stresses analogous to those which 
would confront the human single lung graft. 
Transplantation of one lung followed immedi- 
ately by ligation of the pulmonary artery to the 
opposite lung in an experimental animal would 
force the transplant to provide total gas ex- 
change while carrying the entire cardiac out- 
put. 
Numerous investigators had attempted to do 
this without success in experimental animals 
prior to 1969, although reimplantation of one 
lung followed by delayed ablation of function in 
the opposite lung had been accomplished in 
dogsi'2 and baboons.^ The inability to achieve 
survival after single lung transplantation and 
immediate contralateral pulmonary artery liga- 
tion had been blamed on the fixed and elevated 
transplant vascular resistance which had been 
though to be a consequence of denervation. 
When the transplant with this fixed resistance 
was forced to accept the entire pulmonary blood 
flow, it was thought that intolerable right heart 
failure or fatal pulmonary insufficiency second- 
ary to damage to the pulmonary microvascula- 
ture would result. 
In 1969, we reported the following observa- 
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