OBJECTIVETo observe the effects of surgical delay procedure on the survival of perforator flap with three angiosomes in rat, and to explore its possible mechanism.

METHODSThe flap model was a perforator flap with three angiosomes which located on the right dorsal side of a rat based on the right deep circumflex iliac vessel. The two connection areas between the three angiosomes were successively named choke zone (CZ) 1 and CZ 2 beginning from the pedicle to the remote area. A total of 110 SD rats were divided into routine flap group (RF, n = 40), delay only group (DO, n = 30), and delay flap group (DF, n =40) according to the random number table. (1) In group RF, 30 rats were selected according to the random number table, and flap surgery was performed directly. Six rats were sacrificed on post operation day (POD) 0, 1, 2, 3, 7 respectively to collect the full-thickness skin samples at both CZs for HE staining to measure the vascular density and diameter. The rest 10 rats underwent flap surgery immediately after a catheter was successfully implanted into their external jugular vein. A volume of 1.5 mL sodium fluorescein solution (100 g/L) was injected to the 10 rats on POD 0 (5 rats) or POD 1 (5 rats) each time with a 2-day interval to learn the change in flap circulation. Each rat was injected for 4 times. The flap survival rate of the 10 rats was calculated on POD 7, and the configuration and distribution of the vessels in the flap were observed through angiography with the improved perfusion method of lead oxide-gelatin. (2) In group DO, the right thoracodorsal perforators of all the rats were surgically ligated through a small skin incision, and 6 rats were sacrificed on POD 0, 1, 2, 3, 7 respectively. The skin samples of each rat at the same area as in group RF were harvested to measure the vascular density and diameter. (3) In group DF, rats were treated with ligation surgery as in group DO, and then they were assigned and treated as in group RF on POD 7 with corresponding indexes detected later. Data were processed with group t test, analysis of variance with factorial design, and SNK test.

RESULTS(1) Significant differences of vascular density at both CZ 1 and CZ 2 were found on POD 7 among the three groups ( with F values respectively 2. 69 and 2. 76, P values below 0.05). The vascular density values of CZ 1 and CZ 2 of rats in group DF were (29 ± 7) and (31 ± 8) per mm on POD 7, which were significantly higher than those of group RF [(23 ± 5) and (23 ± 3) per mm2, with q values respectively 5.67 and 6.01, P values below 0.05] and those within group DF on POD 0 (with q values respectively 6.42 and 7. 14, P values below 0. 05). On POD 3 and 7, the vascular diameter values of CZ 1 of rats in groups RF and DF were significantly higher than those of group DO (with q values from 8. 15 to 11.13, P values below 0.05). The vascular diameter values of CZ 2 of rats in group DF onPOD 0, 1, 2, 3,7 [(65 ± 8), (63 ± 13), (69 ± 9), (67 ± 8), (64 ± 13) 230m] and in group DO on POD 3 and 7 were significantly higher than those in group RF [respectively (46 ± 10) , (40 ± 9), (43 ± 13), (46 ± 12), (47 ± 11) µm on POD 0, 1,2, 3, 7 ] at corresponding time point (withqval- ues from 7.29 to 10.79, P values below 0.05). The difference in vascular diameter between CZ 1 and CZ 2 was statistically significant in groups RF and DO on POD 3 and 7, and in group DF on POD 0, 1 , and 2 (with q values from 5.32 to 9.56, P values below 0.05). Compared with that on POD 0 within each group, the vascular diameter of CZ 1 in groups RF and DF and that of CZ 2 in group DO increased significantly on POD 3 or 7 (with q values from 6.12 to 8.13, P values below 0.05). (2) In groups DF and RF, blood from the pedicle ran through CZ 1 and covered the dynamic territory successfully within POD 7. On POD 0, the blood within all flaps was blocked for about 3 min after going through CZ 1 at 1 cm distal from CZ 2 in group DF and around CZ 2 in group RF. (3) Flap survival rate of rats in group DF was (95 ± 12) % , which was statistically higher than that of group RF [(80 241 9) % , t = 2.91, P <0.01]. All the partial flap necrosis occurred in potential territory. (4) Compared with the vessels in the left dorsal side without surgery, the vessels of CZ 1 in group RF were dilated obviously, and the boundary between vascular trees became indistinct, but the vessels in CZ 2 changed slightly; the vessels in both CZs in group DF were dilated dramatically.

CONCLUSIONSThe delay method could enhance the survival of potential territory in perforator flap with three angiosomes, and it acted mainly by dilating the choke vessels in CZ 2 before flap surgery.

Angiography ; Animals ; Graft Survival ; physiology ; Male ; Necrosis ; Perforator Flap ; blood supply ; physiology ; Rats ; Skin ; blood supply ; Surgical Flaps ; blood supply ; physiology ; Time Factors

OBJECTIVETo develop a new experimental animal model of different a single perforating vessel as its pedicle, and to investigate this vessel can captures how many adjacent angiosomes in different directions.

METHODSThirty-six Sprague-Dawly rats of both sexes were used. The rats were divided into group A, group B and group C. Group A: the unilateral deep circumflex iliac perforator artery- based flap. Group B: the unilateral posterior intercostal perforator artery-based flap. Group C: the unilateral lateral thoracic perforator artery-based flap. An extended dorsal perforator flap measuring up to 13 cm x 6 cm was designed in 36 rats to assess the viability of the flap. The upper margin was located at the level of the tip of the scapula and the lower margin at a level 1 cm below the iliac crest. All flaps were observed for 7 days postoperatively, 72 hours after flap elevation, observe flap dyeing conditions through the vivo fluorescein injection, the surviving flap area was calculated as a percentage of total flap dimensions and the angiosome's structure of the flap was displayed by radiopaque microangiography.

RESULTSNo fluorescence was visible in the distal flap of groups A and C, the whole flap show bright fluorescence in group B. Survival rate of C, A, B were improved in order. Statistic difference is significant (P < 0.01) between group and group. In group A, lead oxide-gelatin angiography shows the cephalic flap necrosis occurred in the bilateral lateral thoracic territories, and the vascular architecture partly disappeared in the necrotic area. In group B, the vascular architecture of flap is unbroken. In group C, the caudal flap necrosis occurred in the bilateral deep circumflex iliac perforator artery territories, and the vascular architecture partly disappeared and disordered in the necrotic area.

CONCLUSIONSThe perforator flap is based centrally on a single perforator, this vessel can capture multiple the second vascular territory. In a direction, the longest distance that the blood supply can reach is the point of the third perforator vessel puncture into skin, which can provide certain theoretical guidance for designing of perforator flap.

Angiography ; Animals ; Female ; Graft Survival ; Male ; Models, Animal ; Perforator Flap ; blood supply ; Rats ; Rats, Sprague-Dawley