174 CARDIAC MODELS 
Table II. — Chronic Hemodynamic Data %vith Subacute Microsphere Injection 
Days postinjection 
Animal Baseline 1 3 5 10 14 21 28 
Average (Group I; 4 mg/kg) 
LVP 132/9 118/15 115/17 117/14 124/22 114/20 132/19 
dp/dt _ _ 2217 1882 1763 1803 1947 1993 2120 
SV - - 87 77 75 76 83 81 64 
CO _. - - - 8.3 8.3 8.4 8.3 8.9 8.8 7.9 
MER 438 398 388 374 418 382 410 271 
Heart weight: 983 gm (960-1240); LV wall thickness: 2.8 cm (2.4-3.1). 
Average (Group II; 5 mg/kg) 
LVP 131/8 110/17 114/20 106/19 111/21 104/20 111/20 104/19 
dp/dt 1958 1532 1538 1373 1452 1290 1450 1600 
SV _ 81 51 55 52 59 56 50 51 
CO 8.2 6.8 6.3 5.8 6.5 6.2 6.4 5.2 
MER 266 302 339 274 321 299 381 
Heart weight: 967 gm (700-1550); LV wall thickness: 2.9 cm (2.6-3.0). 
clinical failure unaccompanieci by shock (see 
Table IV). LVEDP in these animals ranged 
from 18 to 31 mmHg. In addition, all animals 
died with, irreversible ventricular fibrillation 
within 16 to 218 minutes of occlusion.*^ 
DISCUSSION 
The primary intent of experimental ischemic 
heart models is to characterize ventricular dys- 
function during various stages and degrees of 
ischemia and infarction and to then assess the 
ability of therapeutic interventions to alter and 
improve on these observed abnormalities. The 
design criteria for models representing the 
clinical spectrum of failure and shock M^ill be 
presented below. 
Ventricular dysfunction following acute myo- 
cardial infarction is variable. Shock accompany- 
ing acute infarction, and unrelated to arrhyth- 
mias, hypovolemia, pain or drug reaction, 
represents one end of the spectrum. The high 
mortality (66 to 100%) accompanying shock 
makes this entity the major therapeutic chal- 
lenge in the ischemic heart disease area. Table 
V depicts the hemodynamic observations in 
shock reported by several investigators.''"^^ In 
addition, it has become clear that within shock, 
several hemodynamic subgroups may be identi- 
fied and thereby provide pertinent prognostic 
and therapeutic information. The hemodynamic 
criteria for the experimental model which repre- 
sents the clinical variant of acute myocardial 
infarction shock requiring the greatest research 
effort, therefore, are: (a) systolic pressure of 
Table III.- — Cardiogenic Shock Following Rapid Microsphere Infusion 
Basal 
Average 
Range 
Shock (37-85 min.) 
Average 
Range 
HR 
beats/min 
125 
76-162 
118 
85-160 
LVP 
mmHg 
115/6 
95/2-125/10 
71/16 
45/6-95/38 
AP 
mmHg 
115/87 
95/65-125/95 
71/48 
45/25-95/70 
SV 
cc 
74 
51-100 
37 
12-65 
CO 
L/min 
8.5 
6.5-11.0 
3.7 
1.3-5.8 
TPR 
mmHg/ 
L/min 
12.7 
10.8-16.3 
14.2 
10.2-21.4 
Table IV. — Failure Following Large Vessel Occlusion in Conscious Animals 
TPR 
HR 
LVP 
AP 
SV 
CO 
mmHg/ 
beats/min 
mmHg 
mmHg 
cc 
L/min 
L/min 
Basal 
Average 
97 
136/7 
136/90 
81 
7.8 
11.7 
Rangp 
75-112 
118/2-165/10 
118/70-165/105 
72-97 
5.8-8.6 
10.2-13.0 
Failure (10-203 min.) 
Average . . 
107 
118/22 
118/81 
57 
6.1 
13.0 
Range .. . 
101-110 
100/18-135/31 
118/85-135/100 
50-61 
5.5-6.6 
10.1-14.9 
