M. R. MALINOW, J. D. HILL, M, LEES, W. P. MCNULTY AND A. J. OCHSNER III 
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immediately to external stimuli, did not eat or 
drink, did not survive longer than 6V2 hours 
after myocardial infarction, and presumably 
died from cardiogenic shock. Animals that sur- 
vived more than 12 hours remained alert and 
responsive to their environment and ate and 
drank normally. 
Electrocardiogram. Tv^^o main patterns were 
observed, (a) In 25 animals, the S-T segment 
became slightly elevated in leads I and aVL and 
the precordial leads and depressed in leads II, 
CONTROL 3 MIN. 
Ill, and aVF; the S-T displacement became 
marked 3 to 4 minutes later (Figure 2). About 
30 minutes after ligation, a small Q v^^ave ap- 
peared in the standard leads and in leads aVF 
and Vi and increased in amplitude afterwards ; 
a QS pattern developed in the precordial leads. 
Twenty-four hours later the S-T displacement 
tended to disappear in the frontal plane but re- 
mained elevated in the precordial leads. In the 
survivors, the QS pattern persisted up to 4 days 
when they were killed. Postmortem examina- 
22 MIN. 7HRS. 
#326 
Figure 2. — Electrocardiographic changes in a monkey after ligation of the anterior descending coronary artery. 
Pattern (a). 
