K. T. WEBER, J. S. JANICKI, A. A. WALKER AND B. H. DENNISON 
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Figure 3. 
-Diagrammatic representation of data monitoring system, including the calf, paper recorder, tape 
recorder and computer. 
sponses, the analog tape and the digital 
computer facilities (see Figure 3) . 
Hemodynamics 
The following may be derived from the re- 
corded data using digital and analog tech- 
niques: peak, mean and integrated aortic flow 
and pressures ; systolic time intervals including 
electromechanical systole or the QSo period, 
pre-ejection period, and left ventricular ejection 
time; the first derivative of left ventricular 
pressure; mean ejection rate; tension time 
index per beat and per minute; cardiac stroke 
and minute work and cardiac output. 
RESULTS AND DISCUSSION 
Baseline Hemodynamics 
Fourteen calves as previously reported^ were 
utilized for the assessment of baseline hemo- 
dynamics in the resting, conscious state. The 
data and results obtained are presented in Ta- 
bles I and II and Figure 4 and include values 
for left ventricular pressure, maximum rate of 
pressure rise, pulse pressure, heart rate, stroke 
volume, cardiac output and their respective in- 
dices, mean ejection rate, stroke work and 
power, and systolic and diastolic time intervals. 
Similar studies by others'^ have been hampered 
by the need for restraint-tables and sedation. 
Ischemic Heart Model 
Experimental myocardial ischemia and in- 
farction has been studied as previously 
reported^-i" in over 30 calves both acutely and 
chronically. Diffuse myocardial microcircula- 
tory ischemia, of varying severity (dosage), 
has been created using microspheres 6-14 mi- 
cron in diameter. The microspheres were in- 
