36 
CARDIAC MODELS 
% OF 
CONTROL 
150 
HEMODYNAMIC EFFECTS OF MYOCARDIAL INFARCTION 
HR 
CO 
I 
sv 
I 
EF 
i 
dp/dt 
1 
I 
EDV 
I 
Con I 
i 
LVEDP 
5671 I l^tOO 
I 
I 
1 
i 
I 
I 
1 
I 
i 
CONTROL 
["■^ 25 HRS. AFTER Ml 
Figure 2. 
3 DAYS AFTER Ml 
medial limit included the interventricular sep- 
tum midway between its junction to anterior 
and posterior walls of the heart. The lateral 
limit was the anterior 50 percent of the free 
wall of the left ventricle. Expressed as a per- 
centage of left ventricular mass, infarct sizes 
ranged between 5 and 35 percent. 
The expected observation was made that the 
location of the infarction paralleled closely the 
site of occlusion in the coronary artery system 
with the more laterally located infarcts related 
to occlusion of diagonal branches and the more 
anterior and anteroseptal locations more related 
to occlusion of the main LAD coronary artery. 
Actual size of infarction, however, was much 
less related to the size of the vessel occluded 
than would have been anticipated. Occlusion of 
vessels of comparable sizes were found to pro- 
duce infarcts of quite widely variable size, 
ranging from small, focal, subendocardial le- 
sions, to massive transmural ones. 
The lesions which have been observed in the 
coronary arteries range in size and degree from 
minor intimal changes to large zones of frank 
wall destruction. Contrary to the original ob- 
servations of Salazar, we have found a poor re- 
lationship between the extent of vessel wall 
damage and the total amount of energy deliv- 
ered. Comparison of anodal and cathodal cur- 
rent also revealed little difference. Arterial wall 
lesions were always localized, and limited typi- 
cally to the pericardial aspect of the arterial cir- 
cumference. This correlated with the region of 
highest current density. With two exceptions 
