C. GRANT LA FARGE AND W. F. BERNHARD 
technique of choice, and then repeat pressures, 
flows, and angiograms were obtained. 
High-fidelity pressures were recorded in all 
states on magnetic tape (Sanborn 7-channel 
tape recorder) at 30 i.p.s., and played back to 
an 8-channel Sanborn photographic recorder at 
3% i.p.s. tape and 200 mm/sec paper speeds. 
The recordings were subsequently analysed on 
a PDP-9 computer, through an Edwin Indus- 
tries X-Y digitizing table for dP/dt and dP/ 
dt/KP (Vcc = velocity of contractile element 
shortening).^ The simultaneously recorded an- 
giograms were analysed on the same computer 
for left ventricular volumes, mass, and ejection 
fraction. All data were normalized (indexed) by 
dividing raw values by one tenth the square 
root of body weight in kilograms.^'^* 
Hemodynamic Studies: Awake, Rest, and 
Exercise 
In several calves, electromagnetic flow 
probes (Carolina Medical Instruments) have 
been used to study normal resting (6) and 
exercising (1), and failure (1) states, including 
ventricular fibrillation (1). In 3 calves, indwell- 
ing PA, Ao, and LV catheters were used to 
monitor, continuously, the normal (3), ventric- 
ular failure (2), and ventricular fibrillation 
(1) states. In addition to pressure, flows were 
measured at rest (3), during fibrillation (1), 
and during graded treadmill exercise (2) by 
indocyanine green dye dilution cardiac output 
curves. For these studies, a 4-channel Sanborn 
stylus-recorder was used. 
Other Studies: Hematology, Biochemistry, and 
Pathology 
All animals in each category (including 
dogs, but excluding rats) were followed 
daily or biweekly with serial blood tests to de- 
teTmine the long term effects of pumping, as 
previously recorded,^"'^^'^^ or, in the case of the 
Strontium-90 dog, the effects of intracavitary, 
LV myocardial irradiation. In the case of ven- 
tricular failure and fibrillation, additional study 
was made of enzyme levels and blood gases; 
these entities were always normal in other 
experiments. 
77 
Post-mortem examinations were conducted on 
all animals, and on all organ systems. In the 
cobaltous chloride experiments, heart and organ 
weights were recorded. In all experiments, the 
heart was dissected in a standard fashion, and 
weighed. Samples of myocardium, and other 
organs, were sent for microscopic examination. 
LV Failure — Acute: Coronary Ligation and 
Carbon Dioxide (CO^) 
Acute failure is here defined as a re- 
versible state of short duration (less than 
3 hours). Clearly, the technique of coronary 
ligation has been used frequently and will 
be reviewed by other participants in the 
conference. 315. 10 Even in the best hands, the 
technique suffers from two drawbacks: unpre- 
dictability, and high morbidity and mortality. 
Our own attempts to produce reliable, acute 
failure with a clearly defined end-point (pre- 
determined LV end-diastolic pressure) were, 
predictably, as fraught with arrhythmias and 
led as often to death as expected. This proce- 
dure was abandoned. 
The use of CO2 as an indicator (right atrial 
gas bubble to reveal the presence, radiographi- 
cally, of a thickened pericardium or pericardial 
effusion) and its solubility in plasma suggested 
the possibility of acute, reversible coronary oc- 
clusion by a fine stream of bubbles directed by 
catheter into the left coronary distribution. 
Three calves were used in this evaluation: 2 
controls, and 1 calf with an implanted LV by- 
pass pump. The control calves and the pump calf 
were brought to the cardiac catheterization lab- 
oratory for study. Following the usual protocol, 
control state data were taken, including a left 
ventricular biplane angiogram (Figure 13). 
Left ventricular myocardial failure was then in- 
duced by coronary infusion of COo and pressure 
recordings and biplane angiograms repeated. 
Two calves recovered, one (control) progressed 
after the second biplane to ventricular fibrilla- 
tion. The other two returned to the animal 
farm for further hematologic studies. 
LV Failure— Acute: Coronary Cuff 
Aware of the experience of Joison in 1968, re- 
ported in 1969,^'^ we adapted the balloon-cuff. 
