80 CARDIAC 
weighed, and sections sent for microscopic ex- 
amination. 
Total Heart Failure: Ventricular Fibrillation 
Ten calves have been studies during electrical- 
ly induced (8) or accidental (2) ventricular fib- 
rillation: 3 with LV, and 7 vnth LV and RV 
blood pumps. One of the latter was studied in the 
operating room, acutely, open-chest; the rest 
were studied both by cardiac catheterization 
(8) and awake in stall (4: 4 hours, 9 hours, 32 
hours, and 17 days duration of fibrillation). 
Post-mortem examinations were performed. 
RESULTS 
LV Failure— Acute: CO^ 
Carbon dioxide, while inexpensive and simple 
to use, proved disadvantageous for four reasons : 
lack of reproducibility and predictability, arti- 
factual pressure recordings, intravascular CO2 
collection, and morbidity. 
In each of the 3 calves studied, it was difficult 
to reach a stable end-point in LVedp. The suc- 
cess manifest in Figure 1, in elevation of LVedp 
to a frank failure level (125/0-4 mmHg to 
120/26-35 mmHg) is equally not manifest in a 
calf given the same COo dosage by a flow rate 
and time: Figure 2. In this latter instance, the 
pressure of 125/10-18 mmHg reflects minimal 
LV myocardial failure (left side of figure). 
Artifactually influenced recordings of LV 
pressure were produced in 2 calves, one illus- 
trated in Figure 1 (upper right panel, right 
end) by the abrupt drop in peak LV pressure 
from 120/26-35 to 60/35 mmHg. The reason 
for this is illustrated in Figure 3 : the collection 
of CO2 (arrows) reaching the LV cavity by 
way of direct LV-coronary conections and pre- 
senting a blood-COo meniscus at the catheter tip. 
The abrupt blood-C02 interface in the left cir- 
cumflex coronary artery (arrow, Figure 3) can 
only influence recovery in a negative manner. 
In fact, it may well have been this coronary 
blood-gas interface which led one of the 3 calves 
to ventricular fibrillation following the induc- 
tion of failure, and the biplane angiogram. 
MODELS I 
I 
LV Failure— Chronic: Strontium-90 and 
Cobaltous Chloride ^ 
Since neither of these two techniques proved ' 
useful, the results can be presented briefly and 
together. 
The singular absence of response to the radia- 
tion of LV myocardium by the Strontium-90- 
tipped catheter, either hemodynamically or mi- 1 
croscopically, was disappointing. Throughout 
the 3 month follow-up period, LV and Ao pres- i 
sures remained stable, as did blood counts and 
enzyme levels. Microscopic slides showed no ; 
significant abnormality in any of the many 1 
areas sectioned. Minor replacement of myo- 
fibrils by fibrocytes was evident in a few areas. 
On the basis of this study, the technique was 1 
not pursued further, either in dogs or calves. | 
The outstanding deficiency of the cobaltous | 
chloride technique was the toxicity of the drug, ' 
both in rats and in dogs. This toxicity expressed 
itself differently, according to the route of 
administration, and was unpredictable as to 
time of occurrence or severity, in relationship 
to dosage. The solution was most toxic intra- 
peritoneally : early death (1 rat in 3 ; both dogs) 
was preceded by loss of appetite and fever 
(dogs). Subcutaneous administration proved 
less toxic, but in dogs, produced major skin 
sloughing in 4 of the 5. Two of the 3 rats had 
major skin sloughs. The solution was least 
toxic per os, but caused anorexia and profuse 
diarrhea at all dosage levels, in both species. 
In toto, 3 rats (2 intra-peritoneal, 1 subcutane- 
ous) developed congestive heart failure, cardio- 
megaly and ascites, and 2 dogs (subcutaneous) 
showed tachypnea as well. Heart weight-to-body 
weight ratios were increased 15 to 25% in both 
species, compared to controls. The microscopic 
appearance of the heart muscles showed inter- 
cellular edema, hydropic degeneration, round- 
cell infiltrate, and hypertrophic myofibrils. Be- 
cause of the unpredictable and poor results, 
and the toxicity, this technique, too, was aban- 
doned. 
LV Failure— Acute: Coronary Cuff 
The reliability, the reversibility, and the free- 
dom from arrhythmias which mark this tech- 
nique are illustrated in Figure 4, in which, in a 
