50 
CARDIAC MODELS 
24. Kumar, R., Hood, W. B., Jr., and Abelmann, W. 
H. Hemodynamic spectrum of left ventricular fail- 
ure in experimental myocardial infarction. Amer. 
Heart J. 82:713-714, 1971. 
25. Hood, W. B., Jr., Kumar, R., Joison, J., and Nor- 
man, J. C. Experimental myocardial infarction. V. 
Reaction to impaired circumflex flow in the pres- 
ence of established anterior myocardial infarction 
in intact conscious dogs. Amer. J. Cardiol. 
26:355-364, 1970. 
26. Wagner, R., Howland, P., Hood, W. B., Jr., and 
Abelmann, W. H. A servo-controlled, canine model 
of stable severe ischemic left ventricular failure. 
Fed. Proc. 31: 330 Abs, 1972. 
27. Bernhard, W. F., LaFarge, C. G., Husian, M., 
Yamamura, N., and Robinson, T. C. Physiologi- 
cal observations during partial and total left heart 
bypass. J. Thorac. Cardiovasc. Surg. 60:807-819, 
1970. 
28. Norman, J. C, Molokhia, F. A., and Hood, W. B., 
Jr. Primate models of ischemic left ventricular 
failure: Absence of pain reaction with transient 
coronary occlusion. Fed. Proc. 31 : 628 Abs, 1972. 
DISCUSSION 
Chairman La Farge : Thank you very much, 
Dr. Hood, for a beautiful presentation of a 
multi-species approach to the age-old problem 
of coronary occlusion. 
Francis L. Earl, Food and Drug Adm., 
Washington, D.C. : You made a statement that 
swine are hard to work with. In what way did 
you find them hard to work with ? 
Dr. Hood : Yes ; I should clarify our methods 
for studying these animals. To date, none of 
our studies have been done in free-ranging ani- 
mals. Our catheters are acutely inserted under 
local anesthesia and removed at the end of the 
study; then reinserted for restudies. We are 
working with a restrained animal, lying on its 
side, rather than with an unrestrained or other- 
wise free-ranging animal. We have found it very 
difficult to manage Chester White pigs under 
these conditions, even under sedation with var- 
ious drugs. Is this different from your experi- 
ence? 
Dr. Earl: This is a deficiency of your tech- 
nique. I mean : they can be handled. With your 
ingenuity, you should be able to come up with a 
method for handling them. It is not very difii- 
cult. 
Chairman : May I make a brief comment? A 
number of us have worked with pigs and had 
perhaps more difficulties with that species than 
with others. We've had relatively good results 
when working with pigs. They tend to behave 
like dogs, i.e., they are quite trainable, they are 
free-ranging, they eat their own ECG leads and 
anything else that's attached to them ; they are 
quite nice when they are trained, but they do 
present problems which are similar to those 
presented by the dog, except for the clotting 
area. 
M. R. Malinow, Beaverton, Oregon : I would 
like to add that you have to have a lot of inge- 
nuity to work with baboons. They not only eat 
the leads, but also the hands of the experimen- 
ters. 
Chairman : I'd like to ask a question in that 
line which has been raised as one of the topics 
of this whole conference: it is the question of 
intrinsic diseases in animals and animal colo- 
nies. You had a chance to observe several ani- 
mals in a colony. Would you like to comment on 
their behavior, in response to Dr. Malinow, and 
on the intrinsic management of the disease, 
particularly in baboons? 
Dr. Hood: Our experience with baboons is 
still limited at this point. One of the obvious 
problems in all of our dog experiments was the 
spontaneous occurrence of pneumonia which is 
a real problem in chronic animal studies. Our 
studies have at times been hampered, particu- 
larly in the winter season, by pneumonia. We 
have not in this rather large series of 180 come 
across spontaneous abnormalities of the circula- 
tory system or congenital anomalies that have 
limited the study and have not had to discard 
animals on this basis. 
R. E. Goldstein, NIH, Bethesda, Md. : My 
question is how do you decide where to place the 
balloon cuffs. 
Dr. Hood: I think the placement of balloon 
cuffs is an important problem. One would wish 
that there were some way we could assess in ad- 
vance where the animal should have its balloon 
cuffs placed in order to develop just the right 
amount of failure without going into ventricu- 
lar fibrillation, which is clearly related to the 
extent of the ischemic damage. Our practice has 
been to place the cuffs at the tip of the left 
atrial appendage in the dog and in the other 
species, usually beyond the first marginal 
