Arterial Supercharging Research Articles

Further study of hemodynamics in the distal end of multi-territory perforator flap

To summarize and discuss the key factors affecting the hemodynamics in the distal end of the multi-territory perforator flap, so as to provide a theoretical basis for the follow-up research and clinical application in this field. The related recent literature about multi-territory perforator flaps was extensively reviewed, and the concepts and researches of perforasome, choke vessel zone, arterial super-charge, and venous super-drainage were summarized. The multi-territory perforator flap is composed of multiple perforasomes, and there are different types of vascular anastomosis in the choke vessel zones, which have important impacts on the hemodynamics of the flap. In order to ensure the survival of the multi-territory perforator flap, arterial super-charge and venous super-drainage are mainly used in clinical practice. However, no consensus has been reached on the choice of the two techniques. The different distribution of blood vessels in the flap, the number of perforasomes, and the type of vascular anastomosis may be the main reasons for the different results. The location, diameter, and axial characteristics of perforators, the number of perforasomes, and the type of vascular anastomosis are the key factors affecting the hemodynamics of the multi-territory perforator flaps, which should be paid attention to in preoperative design and surgical procedure.

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.

Improvement of multiterritory perforator flap survival supported by a hybrid perfusion mode: A novel strategy and literature review

Perforator flaps have been widely used in clinical Settings, however, unexpected necrosis was still commonly encountered in the distal portions of multiterritory flaps known as Choke zone III. In this study, we introduced a novel hybrid perfusion technique which is different from the established one of arterial supercharging or venous superdrainage to improve multiterritory flap survival with success. In order to ensure the entire flap survival of multiterritory flaps extending to choke zone III, a “hybrid perfusion” mode by anastomosing a distal vein of the flap with a recipient artery was carried out in two cases based on our previous basic study. In addition, a systematic literature review regarding the established microsurgical assistant techniques of arterial supercharging and venous superdrainage techniques were performed. Both flaps survived uneventfully. At a minimal follow-up of six months, both patients were satisfied with the results. This novel hybrid perfusion technique provides a simple new concept in solving partial necrosis of multiterritory flaps. Further practice is guaranteed for better understanding this unconventional attempt.

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

Arterial supercharging and venous superdrainage have been the commonly used vascular augmentation techniques for resolving partial loss of flaps in reconstructive surgery. It remains controversial which one of them is more effective in improving flap survival. The purpose of this study was to compare the effect of distal venous superdrainage and arterial supercharging on the survival of an extended dorsal perforator flap in rats. Sixty Sprague-Dawley rats were randomly divided into three groups (n = 20 in each group). An extended dorsal perforator flap with the size of 3 × 12 cm based on the deep circumflex iliac artery and vein was elevated in each rat. In arterial supercharging group, the thoracodorsal artery was retained as the distal supercharging vessel; In venous superdrainage group, the thoracodorsal vein was retained as the distal superdrainage vessel. In control group, no other arteries and veins were retained except the main vascular pedicle. On the seventh day after operation, the survival area of flap was calculated as a percentage of viable area to the total flap. Vascular changes in the choke zones were assessed by angiography. Microvascular density and diameter were assessed via immunohistochemistry staining of CD31 on the fifth day after operation. The flap survival area in arterial supercharging group was significantly higher than that in venous superdrainage group (98.9 ± 0.8% vs. 81.5 ± 3.5%, p < .001). By gross observation, the extent of dilation of choke zone vessels in venous superdrainage group was smaller compared with that in arterial supercharging group. The density of CD31-positive vessels and the diameter of choke zone vessels in arterial supercharging group were significantly larger than that in venous superdrainage group (23.4 ± 4.6 mm-2 vs. 13.1 ± 4.2 mm-2 , p < .05; and 37.5 ± 5.8 μm vs. 27.8 ± 4.9 μm, p < .05). Compared with venous superdrainage, distal arterial supercharging in the potential territory resulted in better survival of an extended dorsal perforator flap in a rat model.

Which is the Pivotal Vessel in Vascular Supercharging? An Assessment of Three Forms of Vascular Supercharging Models Using Indocyanine Green Fluorescence Angiography

BackgroundThe study aimed to perform continuous and dynamic observation on the blood flow changes in a rat abdominal model of supercharged flaps to examine the roles of arterial and venous supercharging in preventing distal flap necrosis. Materials and methodsEighteen rats were divided into three experimental groups. The left-sided flaps in all groups were used as controls such that the subxiphoid perforator vessels served as the only pedicle. Experimental groups I, II, and III consisted of supercharged right-sided flaps. Group I, the arteriovenous supercharging group, had flaps supercharged by the suprapubic perforator arteries and veins. Group II, the arterial supercharging group, had flaps supercharged by the suprapubic perforator arteries. Group III, the venous supercharging group, had flaps supercharged by the suprapubic perforator veins. Laser-induced near-infrared fluorescence angiography was performed before and after surgery. ResultsAs revealed by near-infrared fluorescence angiography, the control group and venous supercharging group exhibited rapid reductions in blood supply and loss of arterial perfusion in distal areas. The distal flap necrosis was much smaller in the venous supercharging group than in the control group. Both the arteriovenous supercharging group and the arterial supercharging group exhibited adequate perfusion and resulted in full postoperative survival of the flaps. ConclusionsThese findings indicated that the distal arterial hypoperfusion is the major cause of the distal venous stasis and necrosis in the flaps. Sufficient arterial supercharging ensures the distal arterial perfusion and therefore diminishes the occurrence of distal flap necrosis.

Arterial Supercharging Is More Beneficial to Flap Survival Due to Quadruple Dilation of Venules

Background“Choke vessels” are communicating conduits between adjacent perforasomes in the skin. Most researches focus mainly on the arterial aspect of the “choke vessels” and neglect the venous aspect, an imbalance needed to be addressed. Materials and methodsThe study was divided into parts I, II, and III. Part I was for observation of the vascular morphological evolution in the choke zone after flap harvest in rats. Part II was for determination of the importance of the dilation of the arterial and venous components of “choke vessels” by preserving the iliolumbar artery (ILA group) or vein (ILV group). A laser Doppler flowmeter and a speckle flow imaging system were adopted for monitoring the hemodynamic impact caused by the different manipulation. Part III was for corroboration of part II by manipulation of other vessels. ResultsIn part I, the arteries and veins between the iliolumbar and intercostal perforasomes underwent modest dilation, whereas the venules between the veins nearly quadrupled in diameter. In part II, flaps in the ILA group were much more intensive in blood perfusion than flaps in the ILV group. The flap necrosis rate was 0.31 ± 0.07 in the ILV group, being significantly larger than 0.10 ± 0.03 in the ILA group. Part III confirmed that venous superdrainage is less efficacious in reducing flap necrosis than arterial supercharging, in which the position of the additional artery was far more important than the diameter. ConclusionsThe extensive dilation of the venous component of choke vessels makes a more potent compensatory role for venous drainage after flap harvest, indicating arterial supercharging is better in augmenting flap viability than venous superdrainage.

Supercharging Strategies for Prefabricated Flaps in a Rat Model.

Limited survival area is an intractable problem in the clinical practice of prefabricated flaps. This study compared four strategies to find an effective method and to understand the potential mechanisms for supercharging. A prefabricated abdominal flap rodent model was prepared. Rats were randomly divided into five groups (n = 6/group). (A) Control group: prefabricated right side femoral vessels. Based on group A, various prefabricated vessels were added; (B) proximal venous supercharging group: right side superficial inferior epigastric vein (SIEV); (C) proximal arterial supercharging group: right side superficial inferior epigastric artery (SIEA); (D) distal venous supercharging group: left side SIEV; and (E) distal arterial supercharging group: left side SIEA. Macroscopic analysis, near-infrared fluorescence imaging, and microscopy were used to analyze the survival area, fluorescence area, and capillary density. No significant differences in survival areas were found among supercharging groups (B-E), which were larger than in the control group. Near-infrared fluorescence imaging showed the areas of control and venous supercharging groups (A, B, and D) were smaller than in arterial groups (C and E). Capillary density areas in the right part of the flap in proximal supercharging groups (B and C) and left part of the flap in distal supercharging groups (D and E) were all greater than group A, with no significant differences among the other groups. Enhanced neovascularization is a useful supercharging strategy. Both arterial and venous vessel supercharging improved the survival area of prefabricated flaps.

Free Bipedicled Radial Forearm and Posterior Interosseous Artery Perforator Flap Phalloplasty

IntroductionThe free radial forearm (FRFA) flap is universally still considered as the gold standard technique in penile reconstruction. Typically, a considerably large flap is required, often involving almost the entire circumference of the forearm. Partial necrosis may occur at the distal-most (dorsoradial) part of the flap as a result of insufficient perfusion. AimTo describe a new technique using the posterior interosseous artery (PIOA) to supercharge FRFA phalloplasty. MethodsIn a 12-month period, all patients having FRFA flap phalloplasty were enrolled. Perioperative, after complete flap dissection, an indocyanine green perfusion scan was performed. In case of insufficient perfusion at the distalmost part of the flap, a supramicrosurgical anastomosis was performed between the FRFA pedicle and the PIOA (artery only). Main Outcome MeasuresStudied outcomes included the rate of marginal necrosis, surgical time, postoperative posterior interosseous nerve damage and urethral complications (fistula, stenosis or necrosis). ResultsA total of 27 FRFA flap phalloplasties was performed. Anastomosis of the PIOA was needed in 15 cases. No marginal necrosis was observed in these cases. There were no cases of postoperative posterior interosseous nerve damage. There were no significant differences in urethral complications (fistula, stenosis or necrosis) between the 2 groups. Clinical ImplicationsIn selected cases where insufficient perfusion of the dorsoradial part of the flap is present, patients may benefit from arterial supercharging to prevent postoperative marginal necrosis. Strength & LimitationsStrengths include a single surgeon, thus lending continuity of skill and technique, a consecutive series, and 100% short-term follow-up. Limitations include single institution series and a limited number of patients. ConclusionArterial supercharging is effective in improving perfusion of large FRFA flaps used in phalloplasty when dorsoradial hypoperfusion is detected on an indocyanine green perfusion scan. It is a technically challenging addition to the standard technique because of the small size of the vessels, the close relationship between the PIOA and the posterior interosseous nerve, and the vulnerability of the newly constructed intra-flap anastomosis.De Wolf E, Claes K, Sommeling CE, et al. Free Bipedicled Radial Forearm and Posterior Interosseous Artery Perforator Flap Phalloplasty. J Sex Med 2019;16:1111–1117.

Versatility and “flap efficiency” of pedicled perforator flaps in lower extremity reconstruction

The use of pedicled perforator flaps provides an alternative to free tissue transfer for lower limb reconstruction. We use computer-aided image analysis to investigate the versatility of pedicled perforator flaps for the reconstruction of lower limb defects. Between April 2007 and April 2011, a case series of 61 patients with wounds of the lower extremity from knee to ankle were reconstructed with pedicled perforator flaps. We performed 16 pedicled reverse-flow anterolateral thigh (RF-ALT) flaps, 8pedicled medial sural artery perforator (MSAP) flaps, 26 pedicled peroneal artery perforator (PAP) flaps, and 11 pedicled posterior tibial artery perforator (PTAP) flaps. Digital planimetry of defects covered was analyzed and the "efficiency" of each flap was calculated, which allowed the assessment of the merits of each flap in the management of lower limb defects. Flaps healed primarily in 82% of cases (50/61). Approximately 50% of the secondary donor sites required skin grafting. Complications requiring secondary surgery occurred in 18% (11/61) of the cases. Six required secondary skin grafting (10%). One RF-ALT flap was converted into a free flap, one PAP required arterial supercharging, and three pedicled RF-ALT flaps required venous supercharging. Image analysis showed that these pedicled perforator flaps could cover 75% of the surface area of the lower leg. The higher length of perforator allowed for greater "flap efficiency" and better versatility of tissue cover. Image analysis can be used as a modality to assess the versatility of individual flaps in the reconstruction of lower limb defects.

Successful retrograde arterial inflow through a muscular branch in a free anterolateral thigh chimeric flap transfer

In this report, we present a case in which a free anterolateral thigh (ALT) flap was transferred for head and neck reconstruction after oropharyngeal cancer ablation, and a retrograde arterial inflow was used to salvage the flap when the main arterial pedicle showed usual repeated spasms. The flap was raised as a chimera flap comprising a fasciocutaneous flap and a vastus lateralis muscle flap. After reperfusion, the pedicle artery exhibited spasms repeatedly and vascular flow was unstable. Therefore, we performed arterial supercharge. In the distal portion of the muscle flap, a small arterial branch was dissected as a reverse-flow arterial pedicle. The recipient artery was also a retrograde limb of the superior thyroid artery. The flap survived; however, postoperative ultrasonographic echo evaluation revealed that the spastic descending branch of the lateral circumflex femoral artery was obstructed and that the reverse-flow muscular perforator alone nourished the whole flap. In free ALT flap transfer, a small perforator level artery was able to nourish a flap, even in a retrograde manner. Moreover, when the vasculature of the free flap is unstable, retrograde arterial supply to a small perforator can be an option to save the flap transfer.

Vascular pressure monitorization for necessity of vascular augmentation in a rat extended abdominal perforator flap model

In case blood perfusion compromises, vascular enhancement with arterial supercharge or venous superdrainage can increase viability of the flap. In this study, vascular pressure monitorization was used in a rat extended abdominal perforator flap model to reveal intraoperative vascular compromise and the need for vascular augmentation. A rat abdominal perforator flap was designed, which was based on the right second cranial perforator of epigastric artery. Vascular pressures of the flap were monitored continuously for 60 min, by catheters placed in the right superficial inferior epigastric artery and vein. Forty rats were divided into four experimental groups, as follows: group 1 (n = 10, no vascular augmentation), group II (n = 10, arterial supercharge), group III (n = 10, venous superdrainage), and group IV (n = 10, arterial and venous augmentation). Arterial supercharge and/or venous superdrainage were performed by using the left superficial inferior epigastric artery and vein. After the rats were sacrificed on the 7th day, total flap area and necrotic regions were evaluated. Mean arterial blood pressure was found significantly lower (P < 0.05) and mean venous blood pressure was measured significantly higher (P < 0.05) in group I than the groups II, III, and IV. Flap survival area was also larger in the groups II, III, and IV than the group I (P < 0.05). The results of this experimental study demonstrate that arterial insufficiency and venous congestion are almost always present in the rat extended abdominal perforator flap model, similar to deep inferior epigastric perforator flap. When such an extended perforator flap is used, arterial and venous pressure monitorization may be considered as a tool to support intraoperative clinical findings to reveal the need of vascular augmentation and ascertain flap viability.

Blood gas analyses in doubly-vascularised free jejunal transfers

The vascular supercharge (additional microvascular anastomosis) has rarely been used for free flaps, and the blood circulation in the transferred tissue has not been recorded. We have made double vascular anastomoses during free jejunal transfer to reduce the possibility of loss of the flap from vascular occlusion. To evaluate the efficacy of additional arterial and venous anastomoses to improve the circulation in the transferred tissue, we analysed the results of blood gas measurements including venous partial pressure of oxygen ( pO 2) and carbon dioxide ( pCO 2) from the distal arcade vein. The free jejunal transfer was made using two pairs of arterial and venous anastomoses. Blood gas concentrations were analysed in samples drawn from the vein in the jejunal arcade before harvest, after the anastomosis of one paired artery and vein, after an additional arterial anastomosis, and after anastomoses of two pairs of artery/vein. The results showed that the venous pCO 2 was not changed by increasing the number of anastomosed vessels. The venous pO 2 was raised both by an additional arterial anastomosis and by two pairs of anastomoses, compared with that at the other two time points measured ( p = 0.04, p = 0.02, respectively). An additional arterial anastomosis seemed to have more effect on the pO 2 than an additional artery/vein pair. Additional arterial and venous supercharging therefore has a similar effect on hyperbaric oxygenation. This effect is mainly caused by arterial supercharging.

Artery-dominant free jejunal transfer

Although the supercharge (additional microvascular anastomosis) technique is often used in pedicled transfer of parts of the gastrointestinal tract, this is rarely performed during free jejunal transfer (FJT). The differences in blood circulation and outcomes between the usual single pedicle flap and a double pedicle flap are not well known. Therefore, we evaluated the effect of an additional arterial anastomosis in FJT. The FJT was performed using one venous and two arterial anastomoses after hypopharyngeal cancer ablation. To assess the effects of an arterial supercharge, blood-gas analysis, including the venous partial pressure of oxygen (pO(2)) and partial pressure of carbon dioxide (pCO(2)), was performed on samples drawn thrice from the jejunal vein: before harvest, after the anastomosis of a paired artery and vein and after an additional arterial anastomosis. The result revealed that the venous pO(2) was elevated by the additional arterial anastomosis, compared with the two other measuring times (P=0.04). The venous pCO(2) did not show significant changes. By being given a dominant artery, a jejunal flap can develop a physiological circulatory environment and can establish nutritional pathways without adverse effects.

Effect of vascular augmentation on the haemodynamics and survival area in a rat abdominal perforator flap model

A major drawback of the DIEP flap is the compromised venous drainage in the distal area, which is the rationale behind the creation of additional venous anastomoses for better flap survival. Although venous congestion is defined as an increase in the venous pressure, the effect of vascular augmentation on the venous pressure has not been elucidated. We investigated the effects of arterial supercharge and venous superdrainage on the venous pressure and the flap survival area in a rat abdominal perforator flap model. An abdominal perforator flap was raised in each of 30 Wistar rats, with the contralateral superficial inferior epigastric artery (SIEA) and vein (SIEV) isolated for pressure measurements. The changes in the SIEV pressure were recorded while proximal sites of these vessels were opened and closed. Thereafter, the animals were divided into three groups: a control group (n=10, both the SIEA and SIEV were ligated), an enhanced arterial inflow (EAI) group (n=10, the SIEA was left intact) and a supplemental venous outflow (SVO) group (n=10, the SIEV was left intact). The flap survival area was determined 7 days after surgery. The SIEV pressure without vascular augmentation was only 13.2+/-5.9 mm Hg. Compared with the control group, the flap survival area was significantly larger in the EAI group, but not in the SVO group. An extremely high venous pressure was noted when the SIEA was opened and the SIEV was occluded, but there was great variation among the individual animals (range: 21.2-79.6 mm Hg). The necrotic area in the EAI group correlated well with the SIEV pressure (r=0.861). These findings indicate that the major factor contributing to distal necrosis in this rat perforator flap model is arterial insufficiency rather than venous congestion. The results suggest that, as long as the arterial inflow is secure, the venous pressure is a reliable parameter for deciding the necessity of venous superdrainage.

Effect of Venous Superdrainage on a Four-Territory Skin Flap Survival in Rats

In a previous report, the authors demonstrated that distal arterial supercharging is more effective at increasing flap survival. There is no doubt of the benefit of arterial augmentation in flap surgery, but the effect of venous superdrainage is still controversial. The purpose of this study was to investigate how venous augmentation could generate larger flap survival areas with different superdrainage positions in rats. A four-territory skin flap, developed by the authors, was used. Forty rats were divided into four groups, as follows: group 1, flaps based only on the deep circumflex iliac artery and vein; group 2, flaps superdrained with the ipsilateral superficial inferior epigastric vein; group 3, flaps superdrained with the contralateral superficial inferior epigastric vein; and group 4, flaps superdrained with the contralateral deep circumflex iliac vein. On the fourth postoperative day, the flaps were assessed by measurements of necrosis and survival areas. Vascular changes produced by venous augmentation were evaluated angiographically. Compared with group 1 (mean flap survival, 37.8 +/- 5.0 percent), the flap survival areas were significantly greater in the superdrainage flap groups (group 2, 57.4 +/- 6.5 percent, p < 0.001; group 3, 72.4 +/- 21.3 percent, p < 0.001, and group 4, 89.2 +/- 18.8 percent; p < 0.001). Angiographic assessment of the flaps revealed dilatation of the choke vein between the territories and reorientation of dilated veins along the long axes of the flaps. This study demonstrates that venous augmentation is also effective for increasing flap survival, and the distal procedure is more effective than the proximal procedure in arterial supercharging.

Effects of Arterial Supercharging and Venous Superdraining Procedures in Skin Flap Survival in Rats

Effects of Arterial Supercharging and Venous Superdraining Procedures in Skin Flap Survival in Rats

Extended left colon interposition for esophageal replacement using arterial augmentation

Gastric necrosis after esophagectomy is a difficult clinical problem. Remedial operations to reestablish gut continuity usually rely on the use of the left colon as the neo-esophagus. Previous resection of the necrotic stomach, adhesions associated with a multiple redo-laparotomy and the need to use a substernal route to reach the cervical esophagus all conspire to produce a requirement for increased conduit length. We present a case in which the “arterial supercharge technique” was used to provide a colonic interposition with extended length in such a clinical situation.

Extended rat-ear flap model: a new rodent model for studying the effects of vessel supercharging on flap viability.

A new extended rat-ear flap model, with both an axial and a random component, is described. The flap is based on an axial supply by the posterior auricular artery and the posterior facial vein. The random portion, consisting of the rat dorsum, is capable of being supercharged at two separate sites-in the scapular and pelvic regions. There are several advantages to this composite flap. It is a combined axial and random flap. When used as a free flap, the viability of the axial portion serves as an indicator for anastomotic patency. The random portion allows for the investigation of the effects of pharmaceutical manipulation or surgical intervention, e.g., flap supercharging. The results indicate that the axial supply alone can cover approximately 50 percent of the extended rat-ear flap. Moreover, adding supercharging perforators to the random portion significantly increases the area of flap survival. Of interest, an axial vascular supply, coupled with more distal dorsal perforators (pelvic) than proximal (scapular) perforators, may increase survival for the so-called "watershed" area in the middle of the random portion of the flap. Additionally, this study also investigated the relative importance of arterial supply vs. venous drainage, using the extended rat-ear flap model. The flap was either supercharged with both the perforators of the scapular and pelvic arteries, or both scapular and pelvic veins. The results of the study suggests that augmenting venous drainage provides statistically significant improvement (87 percent vs. 51.6 percent) in increasing flap survival, when compared to augmenting the arterial supply. Arterial supercharging provided no improvement in flap survival, when compared to no supercharging (axial vessels + arterial supercharging, 51.6 percent vs. axial vessels alone, 49.9 percent). The results also suggest that providing adequate venous outflow is more important than providing additional arterial blood, and that impaired venous outflow may contribute to some cases of flap failure. However, it should be kept in mind that the best flap survival occurs with both arterial and and venous supercharging.