EXPERIMENTAL CARDIAC SURGERY IN THE CALF 
William J. Donawick and James W. Buchanan* 
ABSTRACT 
The calf has many advantages as an experimental an- 
imal, particularly for intrathoracic and cardiac trans- 
plantation studies. 
Halothane and nitrous oxide were excellent anesthet- 
ics for the induction and maintenance of anesthesia. In 
contrast, barbiturates caused prolonged depression and 
high mortality. Particular attention was required to in- 
sure adequate ventilation during thoracotomy. Large 
tidal volume-high pressure ventilation was necessary to 
provide adequate oxygenation. Pulmonary function was 
impaired by the accumulation of gas in the rumen and 
of mucus in airways. 
The cellular immune response to heart grafts was 
prompt and vigorous but could be successfully sup- 
pressed with antilymphocyte serum. The administration 
of immunosuppressants to the calves increased suscepti- 
bility to infection and in the case of prednisolone, 
delayed wound healing. 
INTRODUCTION** 
The calf is particularly well suited for use in 
cardiac transplantation trials, for intrathoracic 
artificial organ studies, and for evaluation of in- 
tracardiac prostheses. The heart and major ves- 
sels of the calf approximate those of man, are 
strong, and withstand suturing well. With care- 
ful attention to surgical technique, anastomoses 
remain free of thrombosis. The calf closely re- 
sembles man hemodynamically.^ Blood for 
transfusion or for priming an extracorporeal 
oxygenator is readily available from adult cows 
and, since preformed antibodies to foreign 
blood antigens do not exist, the blood need not 
be crossmatched. The calf does not develop diro- 
filariasis, a common endoparasite that compli- 
cates vascular and cardiac surgery in the dog. 
• School of Veterinary Medicine, University of Pennsylvania, 
New Bolton Center, Kennett Square, Pennsylvania 19348 
•* Supported by U.S. Public Health Service Grant 5-RO1-HE-12850 
from the National Heart Institute, by a Grant-in-Aid from the 
Delaware Heart Association, and by private donations to the Heart 
Surgery Fund of New Bolton Center. Dr. Buchanan is recipient of 
a Career Development Award, National Heart Institute, USPHS, 
Grant No. K4-HE-13903. 
The calf is docile, reasonably inexpensive, and 
requires little care. 
Unfortunately, investigators have been ham- 
pered because not enough was known until 
recently about inducing and maintaining anes- 
thesia in the calf, about ventilation during thor- 
acotomy, and about techniques for successful 
cardiopulmonary bypass.-"* With the solution 
of many of these problems, transplantation 
studies with genetically foreign organs were 
possible. Long term organ function required the 
use of immunosuppressants and little was 
known about the immune response of the calf or 
the relative merits of the available immunosup- 
pressants. 
This paper reviews techniques for inhalation 
anesthesia, ventilation, and thoracotomy, de- 
scribes methods for maintenance and treatment 
of calves, and discusses the effectiveness and 
limitations of immunosuppressants used in the 
calf. 
MATERIALS AND METHODS 
One hundred and eighty calves, 60 to 120 kg, 
underwent anesthesia and thoracotomy for 
transplantation of prosthetic and allograft 
heart valves and heterotopic xenograft hearts. 
Anesthesia was induced and maintained with 
nitrous oxide and halothane^ through either a 
Chicago or a North American Drager^ anesth- 
etic apparatus with a Fluotec'^ or Vapor^ hal- 
othane vaporizer, and a Bird^ Mark IV assis- 
tor-controller powered by a Bird Mark VII or 
IX pressure-sensitive respirator. After induc- 
tion, the calves were intubated with a 10-13 
mm i.d. cuffed endotracheal tube 40 cm in 
length. 
* Narkovet, North American Drager, P. O. Box 121, Telford, Pa. 
18969. 
s Fluotec Vaporizer, Cyprane Limited, Haworth, Keighley, Eng- 
land. 
c Bird Corporation, Palm Springs, California. 
289 
