130 
CARDIAC MODELS 
Figure 11. — Schema for synchronous pulsatile venoarterial bypass with oxygenation, indicat- 
ing the sites of cannulation, the disposable oxygenator, the pulse pressure generator and 
the SIMAS controller. 
eters were markedly improved in all dogs (Fig- 
ure 15). Their condition was good with every 
likelihood for recovery, had the dogs not been 
sacrificed one hour after termination of pump- 
ing. At autopsy, aortic wall injury was never 
observed and there was no evidence of embolic 
phenomena nor organ abnormality. 
Group IV— Synchronized Venoarterial Bypass 
With Oxygenation— Survival 
All dogs survived the four hour treatment 
period. Marked improvement in hemodynamic 
and metabolic parameters was observed (Figure 
16). One hour after cessation of circulatory sup- 
port they were still in good condition. Autopsy 
after sacrifice revealed no evidence arterial em- 
boli and histologic studies showed no organ ab- 
normality. Examination of the pulse pressure 
generator following each experiment also failed 
to show eviJence of fibrin formation or blood 
clot. 
Comments— Study II 
The technique of serial ligation of major 
branches of the anterior descending and circum- 
flex arteries used in this Study produced a 
heart failure preparation which overcame some 
of the shortcomings of other methods. It re- 
sulted in extensive localized myocardial ische- 
mia and infarction, and a shock state, prior to 
terminal arrhj^thmia, long enough to enable 
evaluation of various support systems. The cri- 
teria for cardiogenic shock closely corresponded 
to those advanced by Friedberg — reduction in 
venous return, blood volume or cardiac output 
by 30-409' resulting in clinical manifestation 
caused by altered hemodynamics and homeo- 
static changes ; by Agress and Associates — 
acute myocardial infarction proved by electro- 
cardiography or autopsy associated with sys- 
tolic blood pressure of 80 mm. mercury or less 
and clinical signs of peripheral circulatory col- 
lapse and by Dietzman and co-workers — 
