C. GRANT LA FAROE AND W. F. BERNHARD 
85 
Initially, the search for a closed-chest, acute 
failure model directed us towards COo infusion, 
since it was simple to use and reversible. 
Clearly, it proved hazardous generated arti- 
facts, and proved far from reproducible. Thus, 
left coronary occlusion by mechanical means 
as the only alternative, and the balloon cuff- 
occluder technique proved to be very useful. 
Positioned at the time of pump implantation, 
the balloon could later be inflated manually to 
produce a steady-state, arrhythmia-free level 
of failure at a predetermined LVedp. It proved 
eminently reproducible (Viz. Figure 6) in one 
study where, at a 1 week interval, two non- 
pumping failure states yielded the same data 
as are tabulated (singly) in Tables I and II. 
Similarly, from calf to calf, the same reproduci- 
bility and freedom from arrhythmias has been 
evident. The single disaster (balloon inflation 
tube kinking) produced II/2 hours of arrhyth- 
Table I. — Numerical data corresponding to Figure 6. The four hemodynamic states are identified in the left hand 
column. Left ventricular (LV) failure was induced by coronary balloon cuff occlusion. Ao, LV — aortic and 
LV pressures (mmHg). EDV and ESV — end-diastolic and end-systolic volumes. SV = stroke volume. E.F. — 
ejection fraction. Max Vce = maximum velocity of contractile element shortening — dP/dt -4- P. Max 
dP/dt = maximum rate of change of LV pressure during isovolumetric systole. PV work — pressure — volume 
work = area enclosed by the loop. 
ANIMAL 
8 
PUMP 
STATUS 
Ao 
LV 
•EDV 
•ESV 
•SV 
•E.F. 
•MAX V 
CE 
•MAX dP/ 
PV WORK 
mmHg 
mmHs 
ML 
ML 
ML 
mmHg/sec 
mmHg.ml 
OFF 
136/108 
(118) 
136/13 
209 
106 
103 
0.H9 
2.2 
m 
10.7m 
ON 
150/108 
(128) 
23/2 
157 
82 
75 
(2.6) 
800 
1,251 
\ 
1 
OF 
72/57 
(62) 
72/37 
259 
200 
59 
0.23 
0.6 
312 
1.9W 
0« 
133/101 
(111) 
30/6 
203 
135 
68 
0.33 
(1.3) 
315 
1,181 
LV-Ao BLOOD PUMP -CHRONIC 
PRESSURE 
(mmHg) 
Conlrot 
LV Foilure 
Failure + Pump 
Cortiol+ Pump 
130 1 50 170 190 2)0 230 250 
LV VOLUME (ml) 
CALF *I57 
Figure 6. — Pressure-volume work diagrams describing 
the effect on LV function of blood pump assistance 
in control and reversible LV failure states. Corre- 
sponding numerical data are found in Tables I and 
II. 
* Indexed 
Calf ^^157 
