LEFT VENTRICULAR FAILURE AND CARDIOGENIC SHOCK 
FOLLOWING ACUTE MYOCARDIAL INFARCTION: 
A CORRELATION OF CLINICAL AND 
EXPERIMENTAL OBSERVATIONS 
K. T. Weber, R. A. Ratshin, C. E. Rackley and R. 0. Russell, Jr.' 
Left ventricular failure and shock accompanying 
acute myocardial infarction (AMI) remain major thera- 
peutic challenges; Experimental models have been de- 
veloped to improve our understanding of the pathophys- 
iology of these disorders; however, their validity has 
been open to question. In order to establish the experi- 
mental criteria necessary for an appropriate cardiac 
model, hemodynamic observations in 79 patients with 
AMI shock (45, Group A) or failure (34, Group B) are 
reported. No statistically significant difference was 
observed in heart rate (HR), peripheral vascular re- 
sistance (PVR), or left ventricular filling pressure 
(LVFP) between each group. Stroke index (SI), how- 
ever, did reflect an important diff'erentiation between 
failure and shock with a mean value of 18 cc/m" for 
Group A and 28 cc/m" for Group B. Cardiac index (CI) 
was 1.64 and 2.46 L/min/m", respectively. A composite 
literature review of AMI shock (153 patients), includ- 
ing this series, indicated the following mean values; 
HR, 102 beats/minute; SI, 15 cc/m"; CI, 1.5 L/min/m"; 
TPR, 2116 dynes / sec /cm-=^; and LVFP, 22 mm Hg. 
Three experimental models that have been developed 
in conscious and anesthetized calves are described and 
include both slow (4-6 hours) and rapid (15-30 min- 
utes) microsphere (6-14 micron diameter) embolization 
techniques of the left coronary artery, as well as con- 
trolled large vessel coronary occlusions. Persistent 
(3-28 days) , dose-dependent degrees of ventricular 
impairment, at rest and during stress (angiotensin), 
associated with compensatory changes in ventricular 
wall thickness are seen for the slow microsphere infu- 
sion technique. Acute occlusions of the left anterior 
descending or circumflex coronary arteries resulted in 
acute ventricular failure without shock and a high 
incidence of fatal ventricular arrhythmias within 16 
to 218 minutes. Rapid sphere injections, on the other 
hand, produced a stable degree of hemodynamic shock, 
with or without elevations in LVFP, and moderate eleva- 
tions in PVR. 
The criteria for failure and shock models are enum- 
*Depaitment of Medicine University of Alabama, Birmingham, 
Alabama. 
**The research upon which this publication is based was performed 
pursuant to the Medical Devices Applications Program Contract 
#PH 43-67-1418, N.I.H. Grant #HE 11,310; and the Myocardial 
Infarction Research Unit Program Contract #PH 43-67-1441, 
National Institutes of Health. 
erated and comparisons with various experimental 
methods drawn. 
INTRODUCTION** 
Left ventricular failure and cardiogenic shock 
accompanying acute myocardial infarction re- 
main major therapeutic challenges. The inabil- 
ity of presently available medical therapeutics 
to improve survival has prompted the search 
for more aggressive interventions, such as in- 
farctectomy, coronary bypass grafting and cir- 
culatory assist devices. In an attempt to improve 
our understanding of the pathophysiology, time 
course and therapeutic response of the ischemic 
heart during these states, a great deal of effort 
has been devoted to the development of an ex- 
perimental analog. 
However, before one can judge the adequacy 
and reliability of current ischemic heart models 
and evolve design criteria necessary for future 
preparations, a reasonable understanding of 
the clinical problem is necessary. Clearly, at 
present, we do not have all the answers on shock 
and failure and, in addition, obvious shortcom- 
ings always exist in equating experimental and 
clinical data. Aside from these inherent weak- 
nesses, however, we feel that the present state 
of the art for the ischemic heart disease model 
can be assessed, but only after a careful review 
of pertinent and presently available clinical 
findings. The purpose of this paper will be to 
derive and describe experimental design criteria 
by reviewing the clinical and hemodynamic data 
in 79 patients, 45 with cardiogenic shock and 34 
in failure without shock accompanying acute 
myocardial infarction, who were followed in our 
Myocardial Infarction Research Unit. The cor- 
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