Comparison of arterial supercharging and venous superdrainage on improvement of survival of the extended perforator flap in rats

Research Advances in Vascular Remodeling in Choke Vessels of Perforator Flap: A Systematic Review

BACKGROUND

As a significant bridge between perforasomes, choke vessels are the key structure of blood supply expansion, also a prerequisite for preventing distal ischemic necrosis of the multiterritory perforator flap, where the remodeling of choke vessels after flap elevation plays an essential role. This systematic review highlights the underlying mechanisms and clinical ways to promote remodeling of choke vessels, as well as experimental observation approaches to further guide researchers.

METHODS

A systematic review was conducted from 1975 to 2023 through PubMed, EMBASE, Web of Science, and Cochrane database with the key words "choke vessels" and "perforator flap" to investigate the mechanisms and ways to promote remodeling of choke vessels as well as observation approaches. The inclusion criteria and exclusion criteria were set to screen the literature.

RESULTS

A total of 94 literatures were obtained through database retrieval. After removing the duplicate literature, reading the title and abstract, and reviewing the full text finally, 33 articles were included in the final study.

CONCLUSIONS

The underlying remodeling of choke vessels may be related to fluid shear stress, hypoxia, and inflammation. The clinical ways to promote remodeling of choke vessels include surgical delay, arterial supercharge, venous superdrainage, drugs, and stem cells. Various experimental methods of observing microvascular morphology allow for a comprehensive research of choke vessels.

Electrical stimulation promoting the angiogenesis in diabetic rat perforator flap through attenuating oxidative stress-mediated inflammation and apoptosis

Background

Skin flap transplantation is one of the effective methods to treat the diabetes-related foot ulceration, but the intrinsic damage to vessels in diabetes mellitus (DM) leads to the necrosis of skin flaps. Therefore, the discovery of a non-invasive and effective approach for promoting the survival of flaps is of the utmost importance. Electrical stimulation (ES) promotes angiogenesis and increases the proliferation, migration, and elongation of endothelial cells, thus being a potential effective method to improve flap survival.

Objective

The purpose of this study was to elucidate the mechanism used by ES to effectively restore the impaired function of endothelial cells caused by diabetes.

Methods

A total of 79 adult male Sprague-Dawley rats were used in this study. Gene and protein expression was assessed by PCR and western blotting, respectively. Immunohistochemistry and hematoxylin-eosin staining were performed to evaluate the morphology and density of the microvessels in the flap.

Results

The optimal duration for preconditioning the flap with ES was 7 days. The flap survival area percentage and microvessels density in the DMES group were markedly increased compared to the DM group. VEGF, MMP2, and MMP9 protein expression was significantly upregulated. ROS intensity was significantly decreased and GSH concentration was increased. The expression of IL-1β, MCP‑1, cleaved caspase-3, and Bax were downregulated in the DMES group, while TGF-β expression was upregulated.

Conclusions

ES improves the angiogenesis in diabetic ischemic skin flaps by attenuating oxidative stress-mediated inflammation and apoptosis, eventually increasing their viability.

The Effects of Angiosome Morphology on Choke Vessels and Flap Necrosis in a Rat Multiterritory Perforator Flap

BACKGROUND

Although the angiosome concept has been proposed for a long time, very few studies have been done on its morphology. Our study investigated the effects of angiosome morphology on choke vessels and flap necrosis in a rat multiterritory perforator flap.

METHODS

Seventy-two male Sprague-Dawley rats were randomly divided into 3 groups (n = 24/group). The flap contained the right iliolumbar, posterior intercostal, and thoracodorsal angiosomes (TDAVs), termed angiosomes I, II, and III, respectively. Only the posterior intercostal artery and iliolumbar vein were preserved in group 1, whereas only the posterior intercostal artery and vein were preserved in group 2, and only the posterior intercostal artery and thoracodorsal vein were preserved in group 3. Distances from angiosome II to angiosome I (II-I), angiosome II to angiosome III (II-III), angiosome I to the caudal side of the flap (I-caudal), and angiosome III to the cranial side of the flap (III-cranial) were measured. Arteriography, flap necrosis, average microvascular density, and vascular endothelial growth factor expression were evaluated.

RESULTS

The II-I distance was significantly greater than that of II-III (3.853 ± 0.488 versus 3.274 ± 0.433 cm, P = 0.012), whereas the distance of I-caudal resembled that of III-cranial (1.062 ± 0.237 versus 0.979 ± 0.236 cm, P = 0.442). The iliolumbar and posterior intercostal angiosomes were multidirectional, whereas the TDAV was craniocaudal and unidirectional. Seven days after the operation, the choke arteries had transformed into true anastomotic arteries. Flap necrosis was lowest in group 3, followed by group 2, and highest in group 1 (10.5% ± 2.4% versus 18.3% ± 3.5% versus 25.5% ± 4.6%, P < 0.01), whereas group 3 showed the highest microvascular density and vascular endothelial growth factor expression, in contrast to groups 2 and 1, with the lowest.

CONCLUSIONS

The choke vessel adjacent to the craniocaudal and unidirectional TDAV significantly blocked venous return. Increasing venous return may reduce the necrosis.

Effects of Distal Arterial Supercharging and Distal Venous Superdrainage on the Survival of Multiterritory Perforator Flaps in Rats

BACKGROUND

Which one of the two measures, distal arterial supercharging (DAS) and distal venous superdrainage (DVS), is better to enhance flap survival? No consistent conclusions have been reached.

METHODS

All flaps were pedicled on the deep circumflex iliac vessels. Seventy-two healthy male rats were distributed to four groups randomly: DAVS group (distal arteriovenous supercharging group), the thoracodorsal (TD) artery and TD vein were preserved; DAS group (distal arterial supercharging group), the TD vein was ligated; DVS group (distal venous superdrainage group), the TD artery was ligated; control group, the TD artery and TD vein were ligated. Flap survival rate was evaluated on postoperative day 7. Flap angiography was performed to assess vascular changes of the flap. Microvascular density (MVD) was evaluated by hematoxylin and eosin staining, and CD34-positive microvessel density was measured by immunohistochemistry. Vascular endothelial growth factor (VEGF) level was measured by western blot. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were evaluated using specialized commercial kits.

RESULTS

The mean flap survival rate was increased significantly in DAVS and DAS groups than in DVS and control groups. DAVS and DAS groups had higher flap vascularization, MVD, CD34-positive microvessel density, VEGF expression and SOD level compared to DVS and control groups. DAVS and DAS groups also had lower MDA level relative to DVS and control groups.

CONCLUSION

DAS is more conducive to improving the survival rate of the multiterritory perforator flap compared to DVS, mainly by enhancing angiogenesis and preventing ischemia-reperfusion (I/R) injury.

Which one is better for multi-territory perforator flap survival, central perforator artery or central perforator vein?

BACKGROUND

The survival of multi-territory perforator flap is associated with the position of the perforators. This study aimed to explore whether use of the central perforator artery or vein was better for flap survival.

METHODS

75 male Sprague-Dawley rats were randomly divided into three groups (n=25 per group). The flap contained the right and left iliolumbar, left posterior intercostal, and left thoracodorsal angiosomes, termed angiosomes Ⅰ to Ⅳ, respectively. The anastomosis between angiosomes Ⅱ and Ⅲ was termed choke 2. In experimental group 2, only the right iliolumbar vein and the left iliolumbar artery were preserved; in experimental group 1, only the right iliolumbar artery and the left iliolumbar vein were preserved; and in the control group, only the right iliolumbar artery and vein were preserved. On day-7 after the operation, the flap arteriography, intraluminal diameter, average microvascular density, vascular endothelial growth factor (VEGF) expression and flap survival were compared among groups. Moreover, the percentages of the angiosomes were measured.

RESULTS

The dilation of the choke 2 artery was most pronounced in experimental group 2, followed by experimental group 1, and, finally, the control group (p<0.05). Similar results regarding average microvascular density, VEGF expression, and survival rate were found among the three groups. The percentages of angiosomes Ⅰ to Ⅳ were 23.1%, 23.0±3.1%, 23.0±1.9%, and 31.0±3.1%, respectively.

CONCLUSIONS

Compared with the central perforator vein, the central perforator artery was more beneficial in enhancing flap survival. A multi-territory perforator flap with the central perforator artery could capture 3 angiosomes safely.

Different Transfer Forms of the Expanded Forehead Flap Pedicled with Superficial Temporal Vessels to Treat Chin and Submental Scar Deformities

BACKGROUND

The chin and submental regions are located at the junction of the face and neck. Its function and aesthetic appearance can be seriously affected when scar deformities cause the cervicomental angle to disappear. The expanded forehead flap pedicled with superficial temporal vessel(s) is a surgical treatment for chin and submental scar deformities. Different transfer types have developed for this flap based on individual situations. At present, there is no unified treatment strategy for applying this forehead flap to treat different regions and ranges of chin and submental scar deformities.

METHODS

Ninety one cases were collected from patients with chin and submental scar deformities that were treated using the expanded forehead flap pedicled with superficial temporal vessels from January 2008 to December 2018. The authors divided the chin and submental scar deformities into 4 types according to different regions and ranges, and summarized flap survival and complications of 5 different transfer forms used to treat scars for creating feasible treatment strategies. We followed up 76 cases, investigating the satisfaction of appearance and texture of the flaps, improvement of neck movement, and scar recurrence.

RESULTS

Expanded forehead flaps were used to repair 91 cases of chin and submental scar deformities. According to the postoperative flap survival and complications of flap blood supply, the treatment strategies are as follows: Bilateral cutaneous and subcutaneous pedicled forehead flaps are applied to treat scars in bilaterally symmetrical large-scale scars in Zone LCL. Unilateral pedicled forehead flaps are applied to treat small-scale scars in Zone C and Zone L. Unilateral pedicled plus contralateral vascular anastomosis and unilateral pedicled plus contralateral super thin forehead flaps are applied to treat the moderate-scale scars of Zone LC. Mean follow-up period was 81 months (range 28-131), 93.4% (71/76) was satisfied with appearance and texture of the flaps, 97.4% (74/76) was satisfied with the improvement of neck movement, and 2.6% (2/76) occurred scar recurrence.

CONCLUSIONS

Five different types of expanded forehead flaps pedicled with superficial temporal vessels can be used to repair differential scar deformities of the chin and submental regions and achieve good therapeutic effects.