688 
PHYSIOLOGY 
Chairman Veith : Have you done any stud- 
ies comparable to the one you presented on im- 
munosuppressed animals? It would appear that 
the process in humans, though similar, is just 
different enough to make a difference with the 
immunosuppressant drugs. 
Dr. Stinson : We're doing those studies now. 
They will be of great interest because there are, 
I think, noninvasive techniques for patient 
monitoring which can get at the systolic and 
diastolic wave forms of left ventricular func- 
tion in order to correlate the changes seen in 
electrocardiographic voltage — a very sensitive 
index of function changes. We've just begun to 
evaluate resolution of these changes in systolic 
and diastolic performance with successful im- 
munosuppressive therapy. 
Claude Chartrand, St. Ousting Hospital, 
Montreal: Did you differentiate electronically 
the aortic flow signal, and if so, did you get any 
informative data on acceleration? 
Dr. Stinson : No we didn't, but I expect that 
if we had, we would have found changes exactly 
as you found earlier. There is a suggestion from 
some experiments that the acceleration of aortic 
flow does approach a meaningful index of con- 
tractility, although it may not be perfect. In his 
earlier studies. Dr. Chartrand found that the 
differentiated aortic flow pattern was a more 
sensitive index of left ventricular performance 
than was peak velocity or total stroke output. 
