E. L. STANLEY, P. KEZDI AND R. K. KORDENAT 
167 
with heparin only gets you over this short pe- 
i riod of time. 
I might mention another matter which is im- 
portant here. Blair, in his original study, and 
we, in our work, found when using exactly the 
same type of magnesium alloy and inserting the 
coil through and actually traumatizing the coro- 
nary wall, it took several days for the occlusion 
to occur; histologically, however, it was a true 
thrombosis with lamina type construction. In 
our particular study when the arterial wall was 
not damaged at all while the coil was lying in- 
side the lumen, occlusion occurred within twelve 
to twenty-four hours. It was not a thrombosis 
with lamina construction. Instead, it was ac- 
tually a clotting type occlusion with a haphaz- 
ard arrangement of platelets and fibrin. 
As for the first question : it is quite difficult. 
The melting point of palmitic acid is, I believe, 
about 60° C. Originally, we tried to put in some 
sodium chloride and other salts to keep it in so- 
lution, or to dissolve it. This was not possible ; 
so we finally heated up the distilled water solu- 
tion to 60 to 70°. We added very small amounts 
of palmitic acid, and then constantly stirred it 
with a magnet. You end up with a slightly su- 
persaturated solution, but as the temperature of 
the solution drops to 60, 55, and 50°, it does not 
precipitate. Accordingly, the actual solutions 
that we injected into these animals were in fact 
small amounts of a solution which was still 
heated up to 50 to 55° C. 
Dr. Malinow: What happened to the dogs 
when you injected saline at 55° ? 
Dr. Stanley: Absolutely nothing happened 
at all. It is of interest that we also injected up 
to 20 cc. of the same free fatty acid solution 
without the helical coil wiring ; the effects were 
quite different. Over a period of five to ten min- 
utes there were some gradual EGG changes in 
some of the animals. When again injected with 
large amounts of the free fatty acid, the ani- 
mals would demonstrate this gradual loss of 
mechanical systole with terminal arrhythmias 
after five to fifteen minutes. But the postmor- 
tem examination showed no major vessel, or 
even small vessel, occlusion in these animals. 
Specifically, very small amounts injected into a 
large vessel ischemic area seemed to have a pro- 
foundly different effect. 
Ghairman: I'd like to ask you a triple- 
headed question. This is a very nice model if 
you have a very high survival rate, such as 70 % 
in eight or nine days which seems very good to 
me for coronary occlusion techniques. Do you 
consider longer term application? Do you sup- 
pose that the animals could go on living for, 
say, a month to provide a really long term fol- 
low-up ? Have you tried any therapeutic maneu- 
vers, and what do you foresee concerning the 
application of this technique in the artificial 
heart program? 
Dr. Stanley : Yes, we let a few of them, in- 
cluded in this series, survive for up to a month's 
time. I think the survival rate is not due to the 
small occlusion only, but to the fact that we per- 
formed merely a small operation on the neck 
and closed that up ; therefore we do not have an 
infection problem or similar problems. The ani- 
mals that do survive for long periods of time 
are then sacrificed. The wire itself disintegrates 
after two weeks' time. The occlusion site recan- 
nulizes which I think others have demonstrated 
as well. In fact, after three weeks there is a sig- 
nificant recannulization and after a month or 
so, some of these animals showed a rather sig- 
nificant flow back through the vessel that was 
originally occluded. It is accordingly compatible 
with a long-term evaluation of the effect of 
small myocardial infarction. Finally, since this 
is a clotting or thrombotic mechanism, we have 
been interested in the study of various fibrino- 
lytic and other agents in this particular model. 
Likewise, since a gradual occlusion over a pe- 
riod of several hours is involved, the develop- 
ment of collateral circulation is important. It is 
a fine model for that purpose, and we have stud- 
ied various vasodilators and other drugs, medi- 
cations or biochemical approaches so as to im- 
prove oxygen delivery to the heart itself. I 
therefore believe that it is a good model. 
Questioner : What gauge wire was used, and 
what effect did this have on the animal? 
Dr. Stanley : The wire that we used is two 
hundredths of an inch in diameter. Originally, 
most of this work was done using a magnesium 
aluminum alloy which is very hard to come by, I 
might say. One company in Michigan was able 
to supply it for us. More recently we have gone 
