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DISCUSSION 
Chairman P. Kezdi: Thank you Dr. La 
Farge. This was a beautiful presentation of the 
acute and chronic effect of assist devices in 
failure. 
K. T. Weber, Jr., University of Alabama: As 
you know, we've utilized the same technique in 
conscious animals followed up to 28 days with 
microspheres, 6 to 14 mil in diameter. I would 
like to make several points. One is that even 
though we do get compensatory changes, i.e., 
changes in left ventricular wall thickness and 
dilatation up to 65 and 45%, respectively, one 
can get failure expressed under angiotensin 
stress or at rest, depending on the microsphere 
dosage, chronically elevated end diastolic pres- 
sures, reduction in cardiac index of 30%, etc. 
Another point is that when the same dose of 
microspheres is injected acutely over fifteen 
minutes, we can produce cardiogenic shock, as 
opposed to our four to six hour infusion period, 
which gives us the stable diffuse ventricular 
failure. 
Dr. La Farge: I'll make two comments on 
that. When I first gave Frank Hastings this 
technique (and I might add that Dr. Weber's 
beautiful work is in the last two references 
in my paper), it was perfectly clear that the 
results needed to be assessed in normal animals 
not controlled with a pump. I've done a few 
normal animals, although nowhere near as 
many as you have. I have found that in the 
normal animals you can only go to an end- 
diastoiic pressure of around 25 or 26 or you get 
into trouble by either the acute infusion, which 
I use over about a half-hour period, or the 
longer term infusion. I can get away with the 
kind of thing I talked about, like putting an 
end diastolic pressure of 45 mm of mercury 
because I have always that magic way of re- 
versing it. 
Dr. M. Klain, Cleveland Clinic, Cleveland, 
Ohio: I would like to comment on the coronary 
flow in coronary obstruction. We measured the 
oxygen tension in various areas of the myocar- 
dium during the obstruction. We found that 
immediately adjacent to the obstruction in the 
other areas of the myocardium there was an 
increase of myocardial flow. My question is: 
did you see any fibrillation after release of the 
obstruction? We have seen, especially in dogs, 
that after you relieve the temporary obstruction 
you very often obtain fibrillation in about 
twenty minutes. We were also able to decrease 
this fibrillation, as well as the fibrillation after 
obstruction, significantly by injecting xylocaine 
before the obstruction is produced. 
Dr. La Farge : The answer to your question 
is simply no ; we never had any trouble. I think 
the difference between my technique and Dr. 
Hood's and Norman's is that I never completely 
obstructed the left coronary artery. It is a 
partial, almost complete obstruction and that 
just may make the difference. The only fibril- 
lation that I ever saw was in an animal whose 
biplane I showed with the coronary cuff. There 
