B. K. KUSSEROW 
821 
aortic constriction combined with the brief in- 
sertion and withdrawal of a test ring. In con- 
trast numerous renal infarcts were observed 
in all five animals of a third control series in 
which subtotal infrarenal aortic ligation was 
combined with the injection of particulate auto- 
logous blood clot into the aorta immediately 
above the level of the renal arteries. 
Use of the Test Model 
The renal embolus test system has been uti- 
lized in the evaluation of a large number of 
synthetic surfaces for their thromboembolic 
propensity. These have included polyethylene, 
Teflon, polyvinyl chloride, silicone rubber, poly- 
vinyl chloride coated with graphite-benzal- 
konium chloride-heparin, fluorinated silicone 
rubber, polyurethane, epoxy, saturated hydro- 
carbon block copolymer and hydrogel grafted 
polyurethane. All of these materials were char- 
acterized by a relatively smooth, stationary and 
rigid blood-materials interface. To date all sam- 
ples of these rigid synthetic materials with 
smooth surfaces have demonstrated some 
thrombotic surface deposit, renal infarcts, or 
a combination of both following implantation 
periods of 3-5 days in the test model. Ring 
thrombosis has varied in severity from minor 
precipitates, encountered frequently along the 
edges of the ring implants, to nearly complete 
occlusion of the ring by large thrombotic ag- 
gregates which covered major fractions of the 
luminal surface of the implant. Thrombi were 
accompanied in well over 90% of instances by 
unilateral or bilateral renal infarcts. Some rep- 
resentative samples of the thromboembolic pat- 
terns encountered are presented in Table I. 
Renal infarcts varied considerably in size 
ranging from less than 1 mm in maximal di- 
mension to nearly complete infarction of a 
kidney (Figure 4). One ring (GBH coated 
polyvinyl chloride) was grossly free of throm- 
bus, but the kidneys demonstrated several renal 
infarcts (Figure 5). In general the throm- 
boembolic patterns observed to date with this 
test model suggest that thrombosis which oc- 
curs on rigid, synthetic intravascular implants 
with smooth surfaces may be attended by em- 
bolic episodes with great frequency. More- 
over, the composite findings of ring implants 
completely free of thrombus in the presence 
of renal infarcts indicates that the absence 
of thrombotic material on the surface of in- 
travascular prosthetic devices in no way rules 
out the possibility of antecedent thrombosis 
Experiment 
Table I. — Prosthesis-Induced Thromboembolic Patterns Produced in the Renal 
Embolus Test System by Various Materials* 
Ring implant material 
Ring thrombosis 
Renal infarcts 
9 
10 
Polyethylene .... 
Teflon 
Silicone rubber 
Silicone rubber 
Lumen 2/3 occluded by thrombus. 
GBH coated polyvinyl chloride 
GBH coated polyvinyl chloride 
Fluorosilicone polymer 
Epoxy 
Polyurethane coated epoxy 
Saturated hydrocarbon block copolymer.. 
Ring lined with thrombus about 2 mm 
thick. Protrudes caudally. 
Ring lumen nearly occluded by upper 
and lower rim of ring. 
Ring lumen clear. Thrombus on upper 
and lower rim of ring. 
Thrombus on distal rim and in lumen 
of ring. 
Ring completely thrombus free. 
Ring lumen coated by thin throm- 
botic deposit which projects caudally 
from ring. 
Two to three mm patch of thrombus on 
caudal rim of ring. 
Thin thrombotic deposit on lower rim. 
Minor irregular thin deposit of throm- 
bus on surface of lumen. 
Many pale infarcts of varying size 
in both kidneys. 
No infarcts in either kidney. 
Several infarcts in both kidneys. 
Both kidneys extensively infarcted. 
Scattered infarcts in both kidneys. 
Numerous infarcts in left kidney. 
Fewer in right kidney. 
Several small infarcts in right kid- 
ney. None in left kidney. 
Right kidney almost totally in- 
farcted. Left kidney 24-30% in- 
farcted. 
Several infarcts of varying size 
in both kidneys. 
Both kidneys free of infarcts. 
♦From Kusserow, B.=s 
