LVA was performed under local anesthesia in 11 lymphedema patients (1 case of upper extremity lymphedema and 10 cases of lower extremity lymphedema; Table 2) according to previously reported conventional LVA procedures.10 An approximately 2–3-cm–long skin incision was made based on indocyanine green lymphography. After identification of the lymphatic channels and venules appropriate for anastomoses, the vessels were transected. An intravascular stent was subsequently inserted into either the venule or lymphatic channel, depending on the vessel condition. After stent insertion, anastomosis was carried out.
In the supermicrosurgical perforator-to-perforator anastomosis group, either the lateral thoracic artery perforator flap or superficial circumflex iliac artery perforator flap was used and anastomosed to the recipient perforator above the deep fascial layer. The diameter of at least 1 of the recipient or flap vessels was less than 0.8 mm. Seven arterial and venous anastomoses were performed in 7 patients. The recipient vessels included perforators of the descending branch of lateral circumflex femoral artery (anterolateral thigh perforator) in 1, descending genicular artery in 3, perforator of posterior tibial artery in 2, and the ulnar artery in 1 (Table 3).
Fingertip replantation was performed in 5 cases, with 5 arterial and 4 venous anastomoses. All cases involved a crushing injury in 4 men and 1 woman, with ages ranging from 41 to 76 years (mean age, 53 years). Three patients underwent complete amputations, and the remaining 2 underwent incomplete amputations. The amputations comprised 1 thumb, 2 middle fingers, 1 ring finger, and 1 little finger. Based on the Ishikawa fingertip injury classification,11 1 case was a subzone 1 injury, 2 were subzone 2 injuries, and 2 were subzone 3 injuries (Table 4).
Time required for anastomosis and complications were examined. Flap survival rate was also examined in free perforator flap transfer cases and fingertip replantation cases.
In the LVA cases, supermicrosurgical anastomosis was established without any complications or damage to the vessels (Fig. 2). The common problems associated with anastomosis such as catching on the back wall, leakage of lymphatic fluid or blood, or thrombosis were not observed. Patency of anastomosis was confirmed by visualization of lymphatic fluid flow from the lymphatics to the veins and a patency test using forceps. Images of the anastomoses were taken, and several microsurgeons visually checked for patency.
In all cases of perforator-to-perforator anastomoses, flaps survived without complications (Fig. 3). Five cases involved 1 arterial and 1 venous anastomosis, whereas 2 cases involved 1 arterial and 2 venous anastomoses. The common complications associated with anastomosis such as catching on the back wall, leakage of blood, and thrombosis were not observed (Table 3).
Among the fingertip replantation cases, the overall survival rate was 100% (5/5 replants) without associated postoperative complications or nail deformity (Fig. 4).
The mean time required to complete the anastomosis in the present study was 16.4 ± 3.56 minutes using the hemi-IVaS technique.
Supermicrosurgical anastomosis is defined as the microsurgical anastomosis of vessels with a diameter < 0.8 mm, although controversy persists regarding border size. The difficulty of the anastomosis of vessels with a diameter of 0.8 mm is dependent on vessel mobility, obstacles of the surrounding tissue, and vessel wall condition. In the present study, we defined microsurgical and supermicrosurgical anastomosis borders as 0.8 mm in diameter.5
Supermicrosurgical anastomosis is difficult due to small vessel size, thin vessel walls, vessel size discrepancy, and vessel damage. These conditions are frequently encountered in clinical practice because small vessels tend to have thin walls and a high vessel size to diameter ratio. For example, it would be more difficult to anastomose vessels with a diameter of 0.3–0.4 mm than those with a diameter of 1.3–1.4 mm because the diameter ratios are 0.4/0.3 = 1.33 and 1.4/1.3 = 1.08, respectively. To overcome these challenges in performing supermicrosurgical anastomosis, we decided to insert an intravascular stent into 1 side of the vessel.
The advantages of the hemi-IVaS technique are as follows:
- 1) Stent insertion into only 1 side is easy and can be performed quickly;
- 2) It can make the lumen of the thin and damaged vessels visible;
- 3) It can reduce the risk of inadvertent catching of the back wall of the vessel and save time;
- 4) There is greater mobility of vessels while the stent is in place in hemi-IVaS than in the conventional IVaS technique; and
- 5) It is a reasonable method, especially when only 1 side of the vessel has a thin or damaged wall.
On the other hand, the disadvantages of the hemi-IVaS technique are as follows:
- 1) Making the last 2–3 stitches at equal intervals is difficult for beginners in the present method; and
- 2) Careful control of the stent is needed because it is easily removed from the lumen and must be reinserted.
Although IVaS is useful for supermicrosurgical anastomosis, it has some disadvantages including the difficulty and stress involved in inserting the stent in both sides of the vessels as well as time needed to perform the procedure. Additionally, it is difficult to maintain an acceptable stent position within the vessel. In some cases, the surgeon may even fail to remove the stent from the vessel.
The hemi-IVaS technique is helpful even for trained supermicrosurgeons because it can reduce stress during challenging anastomoses in cases such as different conditions in different vessel sides. Furthermore, the reliability of supermicrosurgical anastomosis has yet to be established, so improving supermicrosurgical anastomosis reliability is useful for supermicrosurgery beginners and masters alike. The possibility that stent insertion could damage fragile vessels was reportedly low in 1 electron microscopy observation, which indicated that the lumen will remain intact if this method is correctly applied.
The criteria for using this technique in supermicrosurgical anastomosis are a vessel discrepancy ≥ 1.5 times or 1 side of the vessel having a thin or damaged wall. In clinical supermicrosurgical anastomosis cases, the vessels are in different conditions (e.g., one may have a small diameter or a thin or damaged wall). In such situations, inserting the intravascular stent in only 1 side is especially effective for maintaining the integrity of the lumen of the affected side.
Although supermicrosurgery has been established worldwide, there have been no reports on techniques that have proved its success.15 To our knowledge, this is the first study to use an intravascular stent for supermicrosurgical perforator-to-perforator anastomosis for free flap transfer and examine the usefulness of hemi-IVaS, but future studies are needed to validate our findings.
Hemi-IVaS is a valuable technique to increase the reliability of supermicrosurgical anastomosis. However, further studies are needed to improve its success rate and identify all possible areas for its use.
The authors thank all members in their department for their kind support with data collection and article preparation.
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