K. T. WEBER, J. S. JANICKI, A. A. WALKER AND B. H. DENNISON 
1265 
0 20 40 60 80 100 120 140 0 20 40 60 80 IOC 120 140 
HEART RATE (beats/min) 
Figure 4. — Regression lines for systolic time intervals at various heart rates. Electromechanical systole (QS2) ; 
left ventricular ejection period (LVET) ; the preejection period (PEP) ; diastole (D) ; and the ratio of systole 
to diastole (QS2/D) derived from 14 calves are plotted (in milliseconds) against the normal regression line 
(±1 SD) and heart rate. (J. Surg. Res. XI:383-389. 1971. Printed with permission of the author.) 
The importance of inflation-deflation duration 
or timing and balloon position on intra-aortic 
balloon pumping performance has been re- 
ported (see Figure 7).^^ Studies evaluating 
pumping effectiveness during induced coronary 
insufficiency have also been initiated. 
SUMMARY 
The feasibility of an instrumented conscious 
calf preparation has been demonstrated. We 
have emphasized its application to cardiovascu- 
lar data acquisition and problem solving. Its po- 
tential usefulness in other areas, however, re- 
mains to be determined. We have presented our 
experimentation and data monitoring in some 
detail so that others might better utilize the 
preparation in pursuing other problems of in- 
terest. 
