GERARD S. KAKOS AND H. NEWLAND OLDHAM, JR. 
353 
6. Mitchell, B., Adam, M., Lambert, C, Sunger, U. 
and Shiekh, S. Ascending Aorta-To-Coronary Ar- 
tery Saphenous V in Bypass Graft. /. Thoracis 
Cardiovasc. Surg. 60:457, 1970. 
DISCUSSION 
Chairman Michael P. Kaye: Dr. Kakos' 
very interesting paper is open for discussion. 
Lance Gould, Seattle: You mentioned that 
you increased the constriction to a critical point 
and then measured pressure fall and flow 
changes. How do you evaluate how much that 
constriction was? You indicated 75 per cent or 
so caused no coronary pressure gradient or 
appreciable change in distal circumflex coronary 
flow. 
Dr. Kakos : Yes, 75 per cent is an approxima- 
tion. I'm not sure it's within 10 per cent as a 
critical point. We used a graded constrictor, 
which was a double snare, and measured it. This 
figure refers to cross-sectional area and not 
diameter. 
Dr. Gould : I see. Was the measurement done 
] at the time you were doing the acute experi- 
I ment ? 
I Dr. Kakos : The final measurement was done 
afterwards. We marked the constrictor and 
subsequently measured it. 
Dr. Gould: I see. It very nicely indicates 
what we found in humans with severe lesions 
who were studied post-operatively. If we do in- 
ject the bypass with dye, it very often appears 
to be physiologically constricted, although the 
openings may be there. 
Chairman : Are there any further questions? 
Lloyd Phillips, University of Minnesota: 
Did you have an opportunity to evaluate the 
contribution of the right coronary artery to the 
collateralization of the left side? Also, did you 
have a chance to measure actual flows or vol- 
ume distal to your occlusion on the left side? 
Dr. Kakos: The first part of that I can 
answer by saying no. We did not produce an- 
other model with occlusion of the right coronary 
artery. That is being done now, and, in fact, 
some of these data are now becoming avail- 
able. When you ask if we measured flow distal 
to the occlusion, do you mean during the period 
that the ameroid was occluding this vessel or 
afterwards by free flow into a container? No, 
we did not examine free flow into a container. I 
think that method may be fraught with some 
dangers because you remove all peripheral re- 
sistance and perhaps might not get an accurate 
measurement. We used peripheral coronary 
pressure as a time device for our collateral 
flow. And of course, we also monitored the 
left anterior descending coronary artery flow 
which was, I think, contributing the largest 
amount of blood to the system. 
