Advertisement

The Effect on Venous Congestion of Diverting Arterial Flow in the Arterialized Venous Flap

  • Yu-Te Lin
    Correspondence
    Corresponding author: Yu-Te Lin, MD, MSc, Department of Plastic Surgery, Chang Gung Memorial Hospital, International Master Science Program in Reconstructive Microsurgery, Chang Gung University, Toayuan, Taiwan
    Affiliations
    Department of Plastic Surgery, Vascularized Composite Allotransplantation Center, Chang Gung Memorial Hospital, Taiwan

    College of Medicine, Chang Gung University, Taiwan

    Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan
    Search for articles by this author
  • Charles Yuen Yung Loh
    Affiliations
    Department of Plastic Surgery, Vascularized Composite Allotransplantation Center, Chang Gung Memorial Hospital, Taiwan

    Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taiwan
    Search for articles by this author
  • Shih-Heng Chen
    Affiliations
    Department of Plastic Surgery, Vascularized Composite Allotransplantation Center, Chang Gung Memorial Hospital, Taiwan

    College of Medicine, Chang Gung University, Taiwan

    Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan
    Search for articles by this author
Published:January 07, 2022DOI:https://doi.org/10.1016/j.jhsa.2021.10.021
      An arterialized venous flap is a cutaneous flap based solely on subcutaneous veins. The flap is perfused by nonphysiologic flow of blood from the vein into the peripheral tissue. This nonphysiologic perfusion limits the indications for an arterialized venous flap, and its postoperative complications make it an unpopular choice for reconstruction. When venous flaps are designed following the direction of venous valves (antegrade) in a flow-through fashion, the blood may bypass the peripheral tissue without perfusing the flap. A higher pressure within the efferent end of the vein impedes venous return from the peripheral tissue into this draining vein. Thus, venous congestion of the arterialized venous flap becomes inevitable. We describe our approach to designing an arterialized venous flap in which direct arteriovenous shunting is largely eliminated, thereby transmitting a higher pressure in the periphery of the flap while maintaining a physiologic venous pressure in the efferent vein. This restriction of shunting can be accomplished in a number of ways, depending on the venous pattern within the flap.

      Key words

      An arterialized venous flap is a cutaneous flap based solely on subcutaneous veins. To revascularize the arterial venous flap, 1 end of this vein is anastomosed to a recipient artery, and the other end is connected to 1 or more recipient veins. Thus, the flap is perfused by the nonphysiologic flow of blood from the vein into the peripheral tissue. The indication for a venous flap is to reduce donor site morbidity. The nonphysiologic perfusion limits the application of the arterialized venous flap, and its postoperative complications make it an unpopular choice for reconstruction. Nonetheless, venous flaps can be useful because they are very thin and pliable. The dissection technique for a venous flap is also much easier than for a perforator flap. The anastomosis is less technically demanding when compared with that of perforator flap vessels, which can be smaller and attached to larger, heavier pieces of tissue. In our practice, we use them almost exclusively for the hand or digits, especially for full-thickness volar defects that are not amenable to a skin graft or local flap.
      When venous flaps are designed following the direction of the venous valves (antegrade) in a flow-through fashion, blood may bypass the peripheral tissue without perfusing the flap. The higher pressure within the efferent end of the vein impedes the venous return from the peripheral tissue into this draining vein. Thus, venous congestion of the arterialized venous flaps becomes inevitable.
      Several strategies have been proposed to overcome this problem, such as anastomosing multiple draining veins, using a relatively smaller afferent vein and a relatively larger efferent vein, performing various delay procedures, and transferring the flap in a retrograde orientation such that the valves can serve to divert blood into the periphery of the flap.
      • Woo S.H.
      • Jeong J.H.
      • Seul J.H.
      Resurfacing relatively large skin defects of the hand using arterialized venous flaps.
      • Woo S.H.
      • Kim K.C.
      • Lee G.J.
      • et al.
      A retrospective analysis of 154 arterialized venous flaps for hand reconstruction: an 11-year experience.
      • Byun J.S.
      • Constantinescu M.A.
      • Lee W.P.
      • May Jr., J.W.
      Effects of delay procedures on vasculature and survival of arterialized venous flaps: an experimental study in rabbits.
      • Cho B.C.
      • Lee J.H.
      • Byun J.S.
      • Baik B.S.
      Clinical applications of the delayed arterialized venous flap.
      • Krishnan K.G.
      The venous flaps: an experimental study of the microvascular architecture, the area of perfusion and their correlation.
      • Moshammer H.E.
      • Schwarzl F.X.
      • Haas F.M.
      • et al.
      Retrograde arterialized venous flap: an experimental study.
      Although high rates of success have been reported with these techniques, peripheral ischemia and/or venous congestion remain troublesome, resulting in venous congestion and partial loss of the flap. When the goal of reconstruction is to provide pliable soft tissue coverage of a digit, even a small amount of fibrosis from secondary healing can result in reconstructive failure.
      Our relatively uncomplicated approach has been to design an antegrade flap in which direct arteriovenous shunting is largely eliminated, thereby transmitting higher pressure in the periphery of the flap while maintaining a physiologic venous pressure in the efferent vein. This restriction of shunting can be accomplished in a number of ways, depending on the venous pattern within the flap.

      Indications

      The indications for a venous flap include defects on the hand or digit that cannot be resurfaced by a local or regional flap and composite tissue defects requiring replacement of both tendon and soft tissue (harvesting palmaris longus along with the venous flap in a volar forearm).

      Contraindications

      There is no absolute contraindication for a shunt-restricted arterialized venous flap transfer. A venous flap based on deep-seated superficial veins or with thick subcutaneous fat may not be a good choice as it prevents the visualization of the venous system and makes shunt restriction difficult. When the revascularization of the distal part of the digit is required, a flow-through venous flap is indicated instead of the shunt-restricted arterialized venous flap. We recommend caution while using our technique for very large flaps because adequate control of direct arteriovenous shunting would be more difficult when an abundant venous network exists within a broader territory. In these instances, there is an assortment of thin perforator flaps that can be used.

      Surgical Anatomy

      We prefer the donor site of the forearm for certain reasons:
      The skin thickness at the distal third of the forearm is similar to that of the finger; The veins are of similar caliber for anastomosis with digital vessels; The palmaris longus tendon can be included in the flap whenever necessary; The resulting donor site defect is easy to close and causes little morbidity; The donor and recipient sites can be included in the same operative field.
      Venous networks on the forearm can be mapped with the application of a venous tourniquet or visualized with a commercialized infrared light detector before the surgery. If the veins are not visible with either technique, the design of shunt restriction will be difficult, and a venous flap from the forearm is not recommended.
      The specific method to restrict arteriovenous shunting depends on the venous pattern at the donor site, as described below: (Fig. 1) (Note that all flaps are designed for antegrade flow; therefore, the afferent end of the flap is located more distally on the forearm.)
      • 1.
        II-pattern: Two parallel and separate veins running longitudinally. The arterialized vein is repaired at the afferent end and ligated at the efferent end; when vice versa, the drainage vein is ligated at the afferent end and repaired at efferent end. The inflow vein will be arterialized (pressurized), thus forcing blood into the peripheral tissue, but because there are no gross connections, the outflow vein will maintain a physiologic venous pressure and will permit the drainage of blood from the peripheral tissue.
      • 2.
        H-pattern: Two parallel veins with transverse connecting branch(es). The connecting branches are ligated, and separate veins are used for inflow and outflow (as with II-pattern flaps).
      • 3.
        Y-pattern: One vein entering the afferent end of the flap, bifurcating into 2 branches that exit the efferent end. One of the proximal branches is chosen as the outflow vessel and is ligated near the bifurcation. The remaining segment (the other branch and the single afferent vein) then serves as the inflow vessel. Ideally, the Y-pattern flap should be designed with the bifurcation as distal (near the afferent end) as possible to maximize the length of the outflow vessel passing through the flap.
      • 4.
        λ-pattern: Two distal veins merging into 1 proximally. This is the mirror image of the Y-pattern, and the strategy is the reverse, with the ligation of 1 of the distal branches near the bifurcation. The ligated branch will then provide inflow, and the remaining segment will provide outflow. For the λ-pattern flap, the bifurcation should be located as proximal (near the efferent end) as possible to maximize the length of the inflow vessel.
      • 5.
        I-pattern: One continuous vein running along the length of the flap. Because it must provide both inflow and outflow, the single vein is ligated at its midpoint slightly toward the afferent end so that only the afferent half is arterialized and the efferent half maintains venous pressure.
      Figure thumbnail gr1
      Figure 1Five patterns of shunt-restricted arterialized venous flap can be designed depending on the pattern of the subcutaneous veins at the donor site. The key is to choose the donor site with an abundance of venous channels. Selecting the veins that must be arterialized and ones for drainage can be done here.

      Surgical Technique

      A venous tourniquet is first applied to facilitate the mapping of veins. Following this, an arterial tourniquet is applied, after which exploration of the defect(s) commences. Volar and dorsal incisions are made as appropriate to prepare the recipient’s arteries and veins, respectively. Once the defect is confirmed, a semitransparent template is placed over the defect and then transposed onto the forearm donor site. When creating a template of the defect, the template does not need to be excessively larger than the defect size. The template is reversed to ensure an antegrade design (blood flow in the natural direction of the veins). Once the flap template and pedicles are confirmed, the flap is raised to contain only skin, subcutaneous vein, and subcutaneous fat superficial to the muscle fascia. Shunt restriction is then performed according to the different venous configurations. The final flap inset and anastomosis are similar to any other arterial flap.

      Postoperative Management

      The flap may be monitored following the general guidelines to monitor an arterial flap. Color, temperature, fullness, and capillary refills are reliable. Dextran infusion (500 mL/d) is routinely administered for 3 days. Arterial insufficiency can be recognized when the flap turns pale. Mild congestion with slight discoloration or moderate congestion with blister formation may be encountered, but this rarely interferes with the assessment. When overwhelming congestion is observed, re-exploration is usually indicated. Timely salvage ensures less scarring from secondary healing, which is important for functional outcomes of the hand or finger.

      Pearls and Pitfalls

      • 1.
        The thickness of the skin flap and the diameter of the veins of the distal third of the forearm match that of the finger.
      • 2.
        Antegrade design reduces the incidence of arterial insufficiency due to the competent venous valve at the afferent end.
      • 3.
        Shunt restriction of an arterialized venous flap limits flow-through blood streams, which enhances peripheral perfusion and reduces venous congestion of the flap.
      • 4.
        A semitransparent template can be used to select the best orientation of the flap, in which more abundant venous networks pass through.
      • 5.
        Venous congestion observed at the afferent half of the flap usually becomes apparent until the third postoperative day. We suspect that small branches (nonfunctioning venules) undetectable during the surgery become progressively dilated after the surgery and permit secondary shunting.
      • 6.
        The selection of the donor site for a venous flap has to be performed cautiously, especially for the thin patients. The veins may pass under the skin without any interaction.

      Complications

      We have used the shunt-restricted arterialized venous flap in 22 hands, including 8 flaps for scar contracture release, 13 flaps for immediate trauma reconstructions, and 1 flap for the coverage of the flexor tendon and neurovascular bundles after tumor extirpation. The dimension of the flaps ranged from 1.5 × 2 to 3.5 × 7.5 cm (average 9.7 cm2). The patterns of flaps included 4 II, 5 H, 2 Y, 3 λ, and 6 I. Six of 22 flaps (27%) developed venous congestion to varying degrees. Swelling without color change or mild bluish change in part of the flap was considered as mild venous congestion; when the swelling and bluish change was noticed in the whole flap with blister formation, we considered it moderate venous congestion (Figure 2, Figure 3). In all cases, congestion occurred more obviously at the afferent end of the flap, arose on the second or third postoperative day and gradually subsided within 7–14 days. Two flaps were mildly congested, and 4 flaps (including a flap that required re-exploration) developed blisters and superficial epidermolysis. However, re-epithelialization was evident by the time the blisters sloughed, and no flap developed full-thickness necrosis or fibrosis. Of the different venous configurations, epidermolysis and congestion did occur at a substantially higher rate in those with an I-pattern than in those with the other patterns.
      Figure thumbnail gr2
      Figure 2An example of moderate venous congestion. An I-pattern venous flap was used to reconstruct the soft tissue loss of the middle and ring fingers. The afferent vein was repaired to the radial digital artery of the middle finger and efferent vein to the dorsal vein of the ring finger. Discoloration, swelling, and blister formation at the afferent half of the flap occurred progressively (postoperative day 5).
      Figure thumbnail gr3
      Figure 3The venous congestion gradually subsided from postoperative day 7 to 14 (postoperative day 21).

      Case Illustration

      A 19-year-old woman sustained a crush injury of her right hand. Scar contracture on the volar surface of the middle and ring fingers had been released and resurfaced with full-thickness skin grafts. Relapse of flexion contracture of the fingers occurred. Soft tissue defects were left on the volar surface of the middle and ring fingers after release of the proximal interphalangeal joints. Surgical syndactyly with a shunt-restricted arterialized venous flap was planned. The radial digital artery of the middle finger and a dorsal vein of the ring finger were prepared. The flap was designed and raised at the ispilateral forearm. A 2.5 × 7.5-cm2 λ-pattern venous flap was harvested, and the donor site was repaired primarily. The flap was noted to have mild venous congestion the third and fourth days after the surgery, and the discoloration reduced after day 8 after the surgery. Surgical syndactyly was divided about 1 month after the initial procedure. Even though there was mild destruction in 1 of the articular surfaces, functional restoration was obtained, and no relapse of contracture was noticed at the final follow-up of 1 year (Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, Figure 12, Figure 13, Figure 14).
      Figure thumbnail gr4
      Figure 4Scar contracture on the volar surface of the middle and ring fingers was resurfaced with full-thickness skin grafts. Recurrence of flexion contracture in the digits was evident and unsatisfactory.
      Figure thumbnail gr5
      Figure 5Inability to fully flex the proximal interphalangeal joints was secondary to injury at the proximal phalangeal necks.
      Figure thumbnail gr6
      Figure 6Preoperative x-ray showed acceptable joint space, although mild degeneration could be noted at the middle phalangeal head of the middle finger.
      Figure thumbnail gr7
      Figure 7An extension lag of 50° of the proximal interphalangeal joint in the middle and ring fingers was a major concern for the patient.
      Figure thumbnail gr8
      Figure 8Soft tissue defects formed after the release. Temporary K-wires were passed through the proximal interphalangeal joints to fabricate an orthosis for them in extension after the microsurgical reconstruction.
      Figure thumbnail gr9
      Figure 9An arterialized venous flap, measuring 2.5 × 7.5 cm2, was designed on the ipsilateral forearm.
      Figure thumbnail gr10
      Figure 10Laser Doppler imaging was used to monitor the perfusion of the flap. The afferent end was on the middle finger, and the efferent end was on the ring finger. Better perfusion of the efferent end was observed on postoperative days 1 and 2. This could have been because of the afferent part of the flap having a higher arterial pressure, resulting in more apparent venous congestion. Clinically, more venous congestion was seen after postoperative day 3. The technique of shunt restriction improved venous outflow, which enhanced flap perfusion and reduced morbidity, preventing uncontrolled venous congestion.
      Figure thumbnail gr11
      Figure 11K-wires were removed in 2 weeks. Surgical syndactyly did not interfere with postoperative hand rehabilitation. Acceptable extension was regained in 4 weeks.
      Figure thumbnail gr12
      Figure 12Acceptable flexion of fingers was regained in 4 weeks.
      Figure thumbnail gr13
      Figure 13The flap was divided 4 weeks after the microsurgical venous flap transfer. Debulking of the flap was performed because it was thicker at the mid-forearm level. No relapse of flexion contracture was encountered at 6-month follow-up.
      Figure thumbnail gr14
      Figure 14The finger flexion was the same as preoperative pictures.

      Acknowledgments

      The study was supported by Chang Gung Memorial Hospital, Linkou, Taiwan (grant CMRPG3F0161).

      References

        • Woo S.H.
        • Jeong J.H.
        • Seul J.H.
        Resurfacing relatively large skin defects of the hand using arterialized venous flaps.
        J Hand Surg Br. 1996; 21: 222-229
        • Woo S.H.
        • Kim K.C.
        • Lee G.J.
        • et al.
        A retrospective analysis of 154 arterialized venous flaps for hand reconstruction: an 11-year experience.
        Plast Reconstr Surg. 2007; 119: 1823-1838
        • Byun J.S.
        • Constantinescu M.A.
        • Lee W.P.
        • May Jr., J.W.
        Effects of delay procedures on vasculature and survival of arterialized venous flaps: an experimental study in rabbits.
        Plast Reconstr Surg. 1995; 96: 1650-1659
        • Cho B.C.
        • Lee J.H.
        • Byun J.S.
        • Baik B.S.
        Clinical applications of the delayed arterialized venous flap.
        Ann Plast Surg. 1997; 39: 145-157
        • Krishnan K.G.
        The venous flaps: an experimental study of the microvascular architecture, the area of perfusion and their correlation.
        Br J Plast Surg. 2002; 55: 340-350
        • Moshammer H.E.
        • Schwarzl F.X.
        • Haas F.M.
        • et al.
        Retrograde arterialized venous flap: an experimental study.
        Microsurgery. 2003; 23: 130-134