Transjugular intrahepatic portosystemic shunt in a porcine model: histologic characteristics at the early stage.
OBJECTIVE
The authors attempted to determine the histologic processes that take place during development of stenosis after transjugular intrahepatic portosystemic shunt (TIPS) creation.


METHODS
TIPS were created with metallic stents in 20 healthy domestic pigs (tantalum stents in 10, stainless steel stents in 10). The animals were sacrificed 2-16 days later. All the shunts were examined by means of venography both immediately after placement of the stents and before sacrifice. All histologic sections were assessed with modified Giemsa and basic fuchsin stains. Anti-smooth-muscle-cell alpha-actin stain was used in three specimens. The stenotic reaction was quantified by using standard planimetry techniques and a computerized image-analysis system.


RESULTS
Within 16 days after TIPS placement, 15 (75%) of the 20 shunts were completely occluded, four (20%) of 20 shunts were partially occluded, and one (5%) of 20 shunts remained widely patent (animal died of unknown cause 2 days after the TIPS procedure). Stent occlusion was caused primarily by pseudointimal hyperplasia, which was similar morphologically in the portal, middle, and hepatic portions of the stent. Myofibroblastic proliferation was the most striking feature of the pseudointimal hyperplasia. The average thickness of the proliferation was 2.14 mm, which was 67% of the total diameter of the stent. A mild fibrous or lymphocytic reaction occurred around the stent wires and between the pseudointimal hyperplasia and the liver parenchyma.


CONCLUSIONS
The histologic features of pseudointimal formation in this swine TIPS model closely resemble those in humans. This model may prove useful for evaluating stents and other devices and improving the understanding of restenosis after vascular interventions.
Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
G J
GJ
Teng
M A
MA
Bettmann
P J
PJ
Hoopes
B L
BL
Ermeling
L
L
Yang
R J
RJ
Wagner
D000818:Animals; D003251:Constriction, Pathologic; D006965:Hyperplasia; D011169:Portal Vein / Q000473:pathology; D019168:Portasystemic Shunt, Transjugular Intrahepatic; D011172:Portography; D015607:Stents / Q000009:adverse effects; D013552:Swine; D017539:Tunica Intima / Q000473:pathology