120 
CARDIAC MODELS 
Figure 1. — a. Operative schema for arterio-arterial counterpulsation. Note reduction of aortic systolic pressure 
and augmentation of diastolic pressure during pumping, b. Insert indicating implantation sites of constric- 
tors and flow probes about the anterior descending and circumflex arteries, c. Insert demonstrating technique 
of implanting the coronary sinus catheter. 
coronary artery constriction was determined, 
coronary arteriograms were made according to 
the technique of Robbins ^ and myocardial sec- 
tions taken for histologic examination. 
Experiment II— Hemodynamic Study 
Twenty-three mongrel dogs were operated 
upon. All had coronary artery constrictors im- 
planted as in Experiment I. In the control 
group, an electromagnetic flow probe was 
placed about both coronary arteries 3-4 centi- 
meters distal to the constrictors in 4 dogs and 
a single probe placed about the circumflex ar- 
tery in 7 animals (Figure IB). In the treated 
group, flow probes were placed about both 
arteries in 6 dogs and a single probe about the 
left circumflex artery in 6 animals. The coro- 
nary blood flow was carefully monitored. 
Treated dogs were counterpulsated on the 14th 
day and followed until death or sacrifice after 
30 days. Autopsy examination was then carried 
out. 
