A. Gurlek et al., VENOUS FLAP ISCHEMIA - MICROCIRCULATORY CHANGES IN EXPERIMENTAL FLAPSIN A RABBIT MODEL, Journal of reconstructive microsurgery, 14(2), 1998, pp. 121-126
This study was designed to investigate the simultaneous changes in blo
od flow and microcirculation in an island flap during venous occlusion
(venous ischemia), in an ischemia/reperfusion injury model in the rab
bit. An island groin flap based on the inferior epigastric vessels was
harvested in 15 rabbits. The flap was rendered ischemic for 3 hr (n=5
) or 4 hr (n=10, 5 heparinized and 5 not), by applying a microvascular
clamp to the inferior epigastric vein. Transonic Doppler and laser Do
ppler were used to monitor blood flow in the epigastric artery and mic
rocirculation of the flap for 1 hr after flap elevation, 1 hr after oc
clusion, and for 3 hr at the end of the ischemic period. Venous occlus
ion was followed by a rapid decrease of blood flow and microcirculatio
n readings. After ischemia, both blood flow and microcirculation readi
ngs in the flap were significantly decreased, compared to pre-ischemic
values in all groups. In the 3-hr ischemia group, blood flow readings
returned to pre-stress values, while microcirculation remained signif
icantly lower. In the 4-hr ischemia group treated with heparin, blood
flow in the artery settled at levels significantly lower than pre-stre
ss readings; however, microcirculation of the flap was ultimately full
y restored to pre-ischemic values. in the 4-hr ischemia group, both bl
ood flow and microcirculation in the flap settled at levels significan
tly lower than pre-stress values. The authors concluded that tolerance
for venous ischemia is time-dependent in this model and that venous i
schemia is more deleterious than global ischemia. Administration of he
parin may alter the time frame of ischemia/reperfusion injury and may
prevent the harmful effects of injury at the microcirculatory level.