EXPERIMENTAL MYOCARDIAL 
INFARCTION BY CLOSED CHEST TECHNIQUE 
E. L. Stanley, P. Kezdi and R. K. Kordenaf 
This paper describes our experience in development 
and evaluation of a myocardial infarction model de- 
signed to closely resemble the human condition. Proxi- 
mal coronary artery occlusion occurs in the awake, in- 
tact dog by gradual thrombosis occurring from two 
hours to two days, depending on the type of metallic 
material used. Copper alloys clotted in one to two 
hours while magnesium alloys clotted over a period of 
48 hours. 
The sequential electrophysiologic and hemodynamic 
changes produced by the myocardial infarction were 
evaluated from ECG's, aortic blood pressures, cardiac 
output by dye dilution technique, and enzyme determi- 
nation. In 43 dogs the helical coil wire was placed in ei- 
ther the left anterior descending branch (24 animals) 
or the left circumflex artery branch (19 animals). Se- 
rial ECG's showed tachycardia followed by A-V disso- 
ciation and idioventricular rhythm and PVC in six to 
eight hours. S-T segment depression progressed to S-T 
segment elevation and Q-waves were noted by 24 
hours. The A-V dissociation persisted for 48 hours and 
then reverted back to sinus rhythm. Sixty-three % of 
the animals survived greater than 48 hours with most 
of the early deaths due to the untreated arrhythmias. 
The cardiac output decreased 35% and the blood pres- 
sure 30% with a gradual return towards preinfarction 
levels. SGOT's were elevated (300 units). Post mortem 
examination showed complete occlusion at the helical 
wire site and a myocardial infarction that closely re- 
sembled the human condition. The average infarction 
weight was 22 grams (average heart weight of 150 
grams). This model closely resembled the human con- 
dition; coronary artery occlusion occurred by thrombo- 
sis, a small myocardial infarction with arrhythmias de- 
veloped and a 70% survival rate with gradual return of 
the hemodynamic values toward normal was noted. 
INTRODUCTION** 
Numerous models of experimental my- 
ocardial infarction have been developed in the 
past.i"^ No one of these models hov^^ever simu- 
lated closely the clinical myocardial infarction. 
An ideal model should include: (1) single or 
multiple segmental occlusions of the coronary 
* Cox Heart Institute, 3525 Southern Boulevard Dayton, Ohio 
*• This work was supported by NIH Contract PH-43-68-688 and 
Grant HE09885. 
artery by a gradual occluding process without 
thoracotomy; (2) a predictible time of my- 
ocardial infarction in the awake intact animal 
and; (3) electrophysiologic, hemodynamic, and 
prognostic results similar to the experience in 
the human condition. The ideal model v^ould 
also permit sequential studies in the intact ani- 
mal of the events prior to, during, and v^^ith re- 
covery from myocardial infarction, and the 
efficacy of measures for its prevention and treat- 
ment. 
The present paper describes our experience 
in development and evaluation of a myocardial 
infarction model that was designed to closely 
resemble the human condition. Proximal coro- 
nary occlusion occurs in the awake, intact ani- 
mal by gradual thrombosis following insertion 
of a helical coil wire into a coronary artery.'* 
The technique of the helical coil wire insertion, 
sequential electrophysiologic and hemodynamic 
measurements, and general applications of this 
model are described in the paper. 
METHODS AND MATERIALS 
In this study, mongrel dogs of both sexes 
weighing from 15-25 kg were used. A total of 
71 dogs were studied. The animals were sedated 
with morphine sulfate and, under sterile condi- 
tions, the left carotid artery and jugular vein 
were exposed. A special purpose double catheter 
system that permits selective catheterization of 
the left circumflex and anterior descending 
branches of the left coronary artery was passed 
under x-ray visualization to the root of the as- 
cending aorta (Figure 1). This special purpose 
catheter, constructed by us, consists of a cath- 
eter within a catheter. The outer preformed 
catheter rests against the ascending aortic wall 
and points the inner catheter into the left coro- 
nary artery. The larger catheter (Formacath 
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