546 
HEMODYNAMICS 
Table II. — Cardiovascular Control Measurements in Normal Standing Horses 
Horse No. 
Measurements 
700o0 
70044 
71003 
71006 
71008 
71011 
(Mean) 
End-diastolic 
2019.7 
1165.3 
1985.4 
1929.0 
2056.3 
957.9 
1685.6 
volume ( ml ) 
End-systolic 
113.3 
614.6 
1318.9 
822.0 
1060.5 
490.9 
906.7 
volume (ml) 
Stroke volume 
889.7 
560.7 
666.6 
1107.0 
995.8 
467.0 
779.4 
(ml) 
Stroke work 
895.3 
1084.0 
1173.7 
508.1 
(Gm-meters) 
Heart rate 
54.0 
80.0 
66.0 
75.0 
59.0 
90.0 
70.6 
(beats/min) 
Cardiac output 
48.0 
44.0 
43.9 
83.0 
58.7 
42.0 
53.3 
(L/min) 
Ejection fraction 
44.0 
47.0 
57.4 
48.4 
48.8 
(% EDV) 
50 
40 
30 
ill 
o 
< 20 
X 
o 
►10 
iLl 
o 
a: 
UJ 
a. 
^ EPINEPHRINE 
D ISOPROTERENOL 
NOREPINEPHRINE 
II 
. HEART RATE CARDIAC OUTPUT 
EJECTION FRACTION 
(% EDV) 
STROKE WORK 
Figure 6. — Comparison of the percent change in car- 
diovascular values after intravenous administration 
of Epinephrine, Isoproterenol and Norepinephrine. 
Bars represent the mean of 13 values and brackets 
represents the standard errors of these means. 
lustrated in Figure 5. The direct correlation be- 
tween increased EDV resulting in increased 
stroke work is apparent. 
Catecholamines 
The effects of continuous intravenous infu- 
sion of epinephrine, norepinephrine and isopro- 
terenol are summarized in Table IV and Figure 
6. Horses used in these studies were either 
under the influence of pentobarbital sodium 
anesthesia for the entire period of the experi- 
ment or the anesthesia was induced by pento- 
barbital sodium and maintained on halothane. 
The intravenous infusion of epinephrine 
caused a marked increase in the heart rate, the 
cardiac output, the ejection fraction and a de- 
crease in the left ventricular end-diastolic vol- 
ume (EDV) and end-systolic volume (ESV) 
Table III. a — Effects of Tyrode's Solution Infusion on Cardiovascular Measurements in a Chronic Horse {#0011) 
End-diastolic 
Radius (cm) 
End-systolic 
Radius (cm) 
End-diastolic 
Volume (ml) 
End-systolic 
Volume (ml) 
Stroke 
Volume (ml) 
Ejection 
Fraction 
(% EDV) 
Heart Rate 
( beats/min ) 
Cardiac 
Output 
(L/min) 
Stroke 
Work 
(Gm-meters) 
4.40 
3.40 
1275.0 
588.3 
686.7 
53.85 
86 
58.86 
722.0 
4.50 
3.50 
1363.4 
641.7 
721.7 
52.93 
83 
59.90 
798.2 
4.60 
3.50 
1456.9 
641.7 
815.2 
55.93 
80 
65.21 
916.4 
4.65 
3.50 
1504.9 
641.7 
863.2 
57.35 
79 
68.19 
1025.2 
4.70 
3.55 
1554.0 
669.6 
884.4 
56.90 
81 
71.63 
1074.4 
4.80 
3.60 
1655.3 
698.3 
957.0 
57.81 
82 
78.47 
1310.2 
4.80 
3.70 
1655.3 
758.2 
897.1 
54.19 
83 
74.49 
1285.7 
Table IIL. — Effect of Tyrode's Solution Infusion on Cardiovascular Measurements in a Chronic Horse {#OJfi.) 
End-Diastolic 
Radius ( cm ) 
End-systolic 
Radius (cm) 
End-diastolic 
Volume (ml) 
End-systolic 
Volume (ml) 
Stroke 
Volume (ml) 
Ejection 
Fraction 
(% EDV) 
Heart Rate 
(beats/min) 
Cardiac 
Output 
(L/min) 
3.93 
3.30 
908.5 
537.6 
370.6 
40.79 
86 
31.9 
4.12 
3.50 
1050.6 
641.7 
408.8 
38.90 
80 
32.7 
4.50 
3.45 
1363.9 
614.6 
749.3 
54.93 
86 
64.4 
4.60 
3.46 
1456.9 
614.6 
842.3 
57.81 
86 
72.4 
4.85 
4.125 
1707.6 
1050.6 
657.0 
38.47 
86 
56.6 
