PETERS, DONOVAN, KAWAI, KWAN-GETT, ZWAET AND KOLFF 
ART. HEART CYCLE 
401 
IN FLOW 
OUT FLOW 
AIR OUT 
DIASTOLE (70%) 
SYSTOLE (30%) 
Figure 1. — Schematic illustrating cardiac cycle of one Kwan-Gett, air driven diaphragm artificial heart. Maximum 
stroke volume is 100 cc. 
test is a simple determination of the durability 
of the heart. The artificial heart is placed on a 
mock circulation connected to a drive system 
and allowed to pump continuously against an 
arterial pressure of 100 mm of Hg with an atrial 
pressure adjusted to produce a cardiac output 
of approximately five liters/min. We have had 
one Kwan-Gett ventricle on a test of this type 
for fourteen months without failure. The second 
test is a determination of the hemodynamic 
function of the artificial heart. This test is also 
conducted on a mock circulation. The effects 
of atrial pressure, arterial pressure, heart rate 
and duration of systole on the cardiac output 
are determined. A sample of the function curves 
produced from these tests on a Kwan-Gett heart 
are shown in Figure 2. The effect of allowing 
the heart to exhaust air into a vacuum of 10 
mm Hg as compared to exhausting to atmos- 
phere is clearly shown. A set of function curves 
for a Donovan spherical heart exhausting to 
atmosphere is shown in Figure 3. This allows 
us to completely understand the hemodynamic 
response of the heart before it goes into the 
animal, and illustrates the differences in func- 
tion curves with different designs of artificial 
hearts (i.e., maximum cardiac output increased 
with larger spherical artificial heart) . This 
knowledge allows us to eliminate most of the 
pressure measurements which would be neces- 
sary to control the heart without pre-implanta- 
tion function testing. For example, we can easily 
maintain an animal with the artificial heart 
implanted using only one pressure line for an 
arterial pressure and one pressure line for the 
central venous pressure. 
Artificial Heart implantation Procedures 
In order to minimize surgical trauma and 
blood damage, two implantation methods, other 
than cardiopulmonary bypass, have been de- 
veloped. The rationale for not using cardiopul- 
monary bypass in all experiments was to eval- 
uate the immediate effects of pumping of the 
artificial heart independent of hemolysis and de- 
creased coagulation factors which result from 
use of the heart-lung machine. 
On some occasions, when cardiopulmonary 
