42 
CARDIAC MODELS 
Table I. 
Suitable 
Exact "Trial" Incidence Valid for 
Thoracotomy Unanesthetized Focal Timing of Occlusions Ventricular Shock Serum Chronic 
Method Required Preparation Ischemia Infarction Possible Fibrillation Model Enzymes Studies 
Direct ligation of a 
single large vessel^ + 0 + + 0 variable 0 0 + 
Ameroid constrictor^ + ++ 0 0 71ow 0 possibly + 
Microembolia 0 0* 0 + 0 variable + + ? 
Coronary "plug"* 0 0* + + 0 ?high 0 + ? 
Multiple ligation 
of small vessels^ + 0 + + 0 ?low + 0 0 
Electrothrombosis« 0 0* + + 0 Thigh 0 + + 
Mercury embolization' 0 0* ± + 0 low + + 0 
Metallic wire 
thrombosis^ 0 ++0 0 ?0 + + 
Balloon cuff + + + + + lowO + + 
Anesthesia generally employed, but probably not mandatory. 
alloy wire within a coronary artery through a 
catheter.^ 
The present report deals with the recently de- 
veloped method of coronary occlusion which em- 
ploys a balloon-cuff device implanted about the 
coronary artery.^'^^ Though thoracotomy is 
required, animals may be studied at any time 
after surgery. The exact timing of onset of in- 
farction is possible. A unique feature of the 
method is the ability to carry out one or more 
"trial" occlusions. This permits studies of tran- 
sient ischemia without permanent occlusion. 
The incidence of ventricular fibrillation is low, 
and the method is eminently suited to chronic 
studies of myocardial ischemia. 
METHODS 
Our studies have been carried out over the 
last four years in various animal species, in- 
cluding the dog, pig, calf and baboon. Initially, 
extensive testing of the balloon cuff occlusion 
device was carried out in open-chest anesthe- 
tized animals. "'i^'i^ These studies demon- 
strated the feasibility and consistency of coro- 
nary occlusion with this device. Subsequently 
this methodology was extended to intact con- 
scious animals utilizing single and multiple im- 
plantable coronary artery balloon occluders. 
The method entails implantation of the bal- 
loon-cuff occluders on the left anterior descend- 
ing or circumflex coronary arteries or both 
(Figure 1). The animals were allowed to re- 
cover from surgery for approximately two 
weeks. At the time of study the animals were 
sedated using 0.8 mg/kg of morphine sulfate 
given I.M. for dogs, 2-3 mg/kg of morphine sul- 
fate given I.M. for calves, and 1 mg of mor- 
phine sulfate given I.M. for pigs. Pigs were dif- 
ficult to tranquilize using this regimen, and on 
occasion required 1 mg/kg of phencyclidine or 
more to produce muscle relaxation. For hemo- 
dynamic studies catheters were inserted acutely 
under local anesthesia. Cardiac output measure- 
ments were performed using indocyanine green 
dye as indicator.* 
* Kindly supplied by Hynsbn, Westcott, and Dunning, Baltimore, 
Md. 
0. D. = 2 .4 mm 
1. D. = 0.75 mm 
7.0 mm 
28 cm 
BARGER BALLOON 
Figure 1. — Above: Schematic representation of bal- 
loon cuffs implanted on the left anterior descending 
and circumflex coronary arteries of a dog. Balloon is 
inflated through exteriorized Silastic tubing. 
Below : Dimensions of balloon cuff and tubing. 
