K. Man et al., Liver transplantation in rats using small-for-size grafts - A study of hemodynamic and morphological changes, ARCH SURG, 136(3), 2001, pp. 280-285
Background: Damage to a small-for-size liver graft after reperfusion is fre
quently observed but the mechanism of injury remains unclear.
Hypothesis: Injury to a small-for-size liver graft is related to the change
s of portal pressure and blood flow.
Main Outcome Measures: Survival rates, portal hemodynamics, microcirculator
y changes, and morphological changes (by light microscopy and electron micr
oscopy).
Setting: A rat model of nonarterialized orthotopic liver transplantation co
mparing 2 groups of rats transplanted with whole grafts (100% of recipient
liver weight) and small-for-size grafts (30% of recipient liver weight).
Results: Median survival of the rats with small-for-size grafts was 30 hour
s (range, 27-37 hours). During the first 15 minutes after reperfusion, mean
arterial pressure of the small-for-size graft group was significantly lowe
r than that of the whole graft group (10-minute: 100 vs 132 mm Hg, P=.04; 1
5-minute: 96 vs 127 mm Hg, P=.04). Portal pressure (in centimeters of water
) of the small-for-size graft group was significantly higher in the first 2
0 minutes after reperfusion than the level before the an- hepatic phase (5-
minute: 15.1 vs 9.3, P=.02; 10-minute: 16.1 vs 9.3, P=.03; 15-minute, 13.5
vs 9.3, P=.03; 20-minute: 13.4 vs 9.3, P=.03) and was significantly higher
than chat of the whole graft group in the first 10 minutes after reperfusio
n (5-minute: 15.1 vs 9.6, P=.02; 10-minute: 16.1 vs 10.3, P=.04). Hepatic m
icrocirculatory blood flow (in milliliters per minute per 100 g) was also s
ignificantly higher in the small-for-size graft group during the first 40 m
inutes after reperfusion (S-minute: 16.3 vs 9.3, P=.02; 10-minute: 14.9 vs
6.6, P=.02; 15-minute: 14.8 vs 5.5, P=.02; 20-minute: 13.1 vs 7.0, P=.02; 3
0-minute: 13.2 vs 8.8, P=.04; 40-minute: 14.6 vs 7.1, P=.02). Light and ele
ctron microscopy showed normal morphological features of whole graft up to
24 hours after reperfusion. The small-for-size graft, however, showed sinus
oidal congestion, tremendous swelling of mitochondria of hepatocytes, irreg
ular large gap of sinusoidal lining cells, and collapse of the space of Dis
se.
Conclusions: In a rat model, the portal hemodynamic changes in small-for-si
ze grafts are transient. Progressive damage of the graft may result from mi
crocirculatory failure due to irreversible endothelial injury after reperfu
sion.