Super-Microsurgery for Vessels with Diameters Smaller Than 0.5 mm

Introduction

Microsurgery is a skilled technique used in specialized surgical procedures of plastic and reconstructive surgery. Unlike conventional surgical procedures, microsurgery is performed under a microscope; therefore, training is required before the actual surgery is performed. Several studies have reported microsurgical training using artificial blood vessels, food such as chicken, and laboratory animals such as rats.^1–3 In the past, we have trained young surgeons, medical students, and overseas doctors with various clinical experiences and reported on the significance of microsurgery training. ⁴ In addition, there are numerous reports on the anastomotic technique of microsurgery in the literature,^5–8 with the author contributing to several of these reports. ⁹ From these experiences, it is believed that many skills necessary for actual microsurgical procedures can be acquired preoperatively through an excellent training program.

The development of microscopes and surgical techniques has led to the establishment of super-microsurgical techniques for blood and lymphatic vessels with diameters <1 mm. Its indications are rapidly increasing with the development of lymphatic surgeries, such as lymphaticovenular anastomosis^10–12 and lymph node transfer with vascular pedicles, for lymphedema.^13–15 In LVA, the lymphatic vessels to be anastomosed are generally <1 mm in diameter; therefore, the procedure’s anastomosis technique must vary from conventional microsurgery to maintain accurate and long-term patency. We previously reported on the LVA method for maintaining long-term patency using an experimental animal model.^16,17

In some cases of LVA of the upper extremity or the thigh, groin, and lower abdomen, the lymphatic vessels and veins to be anastomosed are <0.5 mm in diameter. Among super-microsurgical techniques, the anastomosis of vessels smaller than 0.5 mm is considered very difficult to perform due to the small diameter and thinness of the vascular or lymphatic walls. This presents difficulties in accurately performing the anastomosis and ensuring patency of the anastomotic site, as inserting a forceps into the lumen of such vessels is often not feasible. In this article, we report on the main points of super-microsurgery, particularly on the anastomosis of veins and lymphatic vessels smaller than 0.5 mm.

Materials and Methods

LVA with the anastomosis of veins and lymphatic vessels smaller than 0.5 mm was performed in 20 anastomoses. Institutional Review Board approval was not obtained because the study was not eligible. The type and stages of lymphedema, the caliber of lymphatic vessels and veins anastomosed, venous reflux, additional anastomosis by leak, and anastomosis time were examined. Venous reflux was classified into four levels as follows: none, mild, moderate, and severe. For the various measurements, a crack scale was used.

Anastomosis for vessels with diameter <0.5 mm

It is generally easier to perform when the vascular vessels are placed horizontally. The following is a case study involving a right-handed surgeon: the blood vessel farthest from or located to the right of itself was defined as the first blood vessel, whereas the other blood vessel was defined as the second blood vessel. (1)

The outer wall of the first blood vessel near the abrupt end hook with the tip of the needle in the needle holder. The entire abrupt end of the first blood vessel was supported by a forceps on the left-hand. In other words, the first blood vessel was positioned between the needle and the forceps. The key was for the forceps to gently hold the entire vessel without grabbing it.

(2)

The surgeon decides the entry point and angle of the needle while moving the tip. After the needle was fixed, a force was applied to the needle and needle holder to pass through the needle to the vascular wall.

(3)

It was confirmed that the tip of the needle is located in the lumen of the first blood vessel after passing through the needle (Fig. 1).

(4)

The tip of the needle was inserted into the lumen of the second blood vessel, and the bite was adjusted while poking the second blood vessel from the endometrium.

(5)

Once the tip was properly positioned, counter-traction was applied by holding the entire outer wall with a left-hand forceps. Step (4) was repeated if the position was found to be incorrect.

(6)

The part near the tip of the needle was held, and the needle was pulled out along its curvature (Fig. 2).

OPEN IN VIEWER

FIG. 1.

Threading the needle into the first vascular canal. Left: The entire vascular canal was held without inserting a left-hand setter into the lumen. Center: Force was applied to the needle holder in the right-hand and the setter in the left-hand. Right: The needle tip is inserted into the lumen of the first canal.

OPEN IN VIEWER

FIG. 2.

Threading the needle into the second vascular canal. Left: The bite is adjusted by probing the lumen of the second vascular canal using a needle tip. Center: Force is applied to the needle holder in the right-hand, and the needle is threaded into the second canal. Right: After threading both canals, they were pulled out along the needle’s curvature.

Results

Anastomoses of lymphatic vessels and veins smaller than 0.5 mm accounted for about 10% of all anastomoses. Of the 20 anastomoses, 9 were in the upper extremity and 11 in the lower extremity. One anastomosis was for primary lymphedema and 19 were for secondary lymphedema. The stages of lymphedema had the following distribution: seven cases of stage 1 lymphedema, seven cases of stage 2, four cases of late stage 2, and two cases of stage 3. The lymphatic vessels were on average 0.375 mm (0.2 mm to 0.5 mm) in diameter, and the veins were on average 0.435 mm (0.3 to 0.5 mm) in diameter. Venous reflux was observed in three patients: two with mild and one with moderate reflux. All anastomoses were performed with 6 to 8 stitches. No additional anastomosis due to leakage from the anastomosis was necessary in any case. The anastomosis time was 11.35 minutes on average (9 to 14 minutes) (Table 1). The patency rate for the 20 anastomosis was also 100%.

Discussion

Few studies have reported the technical details of super-microsurgery, and surgeons have used a variety of methods based on their own experiences. This has been an obstacle to the widespread use of super-microsurgery. The author has published several educational videos demonstrating the techniques of super-microsurgery, which encompass strategies for overcoming technical difficulties in super-microsurgery.^18,19 The biggest technical difference between microsurgery and super-microsurgery, especially when anastomosing a blood vessel of 0.5 mm or smaller, is the inability to apply counter-traction by inserting the forceps held in the hand opposite the needle-handled device into the lumen of the anastomotic blood vessel. In vessels smaller than 0.5 mm, it is preferable not to forcibly insert the forceps into the lumen because of the possibility of laceration or damage to the vascular wall due to insertion, even when the forceps can be inserted. Few reports have described the technical details of how to accurately thread a needle in the absence of counter-traction. This report highlights several important points regarding needle threading in super-microsurgery, which is the key to successful anastomosis and long-term patency.

Another challenge is the detailed adjustment of the bite during anastomosis. If sutures are not made with an appropriate bite for each stitch, wrinkling of the vascular wall at the anastomotic site may occur. In addition, if the bite is too small, the vessel wall may be avoided during anastomosis. However, if the bite is too large, it may cause anastomotic occlusion due to the exposure of the intima at the anastomotic site. In super-microsurgery, failure to adjust the bite even with one stitch can cause torsion of the entire anastomosis, directly affecting its success. The authors are conscious that the bite should be approximately the same size as the thickness of the blood vessel, especially when there is a difference in the caliber of anastomotic vessels.^20,21

In an LVA, the most desirable anastomosis is to accurately anastomose lymphatic vessels with good lymphatic flow and veins with a high drainage effect.^12,22,23 Lymphatic flow in lymphatic vessels is not directly related to the diameter of the lymph vessels or their size.^24,25 In actual surgery, lymphatic vessels with a large diameter but low lymphatic flow due to degeneration, and lymph vessels with a small diameter but with high flow are often identified. ²⁰ Therefore, even with small lymphatic vessels, good lymphatic drainage and associated surgical effects can be expected in some cases of anastomosis. In the present study, venous reflux was observed in three cases. During LVA, the vein and lymphatic vessels must be in close proximity for anastomosis to perform. Some veins may have backflow; however, identifying one with no backflow is preferable as it allows for good drainage. Generally, smaller veins have less backflow from the cut end, and anastomosis of a small but high-flow lymphatic vessel with a slight difference in caliber and no backflow is the most ideal.^25–27

Once a surgeon is familiarized with this anastomosis procedure, they can typically perform one anastomosis in about 10 minutes. For example, in lymphaticovenular anastomosis it takes approximately 15 minutes to identify the lymphatic vessels and veins for anastomosis and closure of the wound, and the entire procedure of 3–4 anastomoses can be performed within 1 hour.

Conclusion

The important points of LVA for lymphatic vessels and veins smaller than 0.5 mm were reported. The condition of lymphatic vessels in patients with lymphedema varies, and the ability to anastomose lymphatic vessels of various sizes to the veins can be applied to a variety of cases at different stages of the disease. Once a surgeon is familiarized with this anastomosis procedure, they can typically perform one anastomosis in about 10 minutes.