Techniques


Fig. 3.1

Surgeons working position at microscope



For both surgeon and assistant, the ideal position for a micro-anastomosis is on the surface, not in a deep hole or under a bony shelf; neck extension on the operating table may be useful. Exposure must be adequate to access a good length of recipient vessel; careful use of self-retaining retractors or sutures to hold back the skin edge will further refine anastomotic exposure and access. An accurate hemostasis of the surgical field represents a keystone in performing a microsurgical procedure. A continuous trickle of blood is a very disturbing complication, and blood may stick on the vessel wall and become difficult to remove after a fibrin clot formation. A frequent irrigation and usage of moistened gauze may help to solve this problem. Vessels to be anastomosed should be parallel to the surgeon, and the vessel lumen should be on the same plane and clearly in view.


The surgeon and assistant should be themselves opposite each other ideally sitting on height-adjustable stools and with their hands comfortably supported. Correct positioning of the hand is important to avoid tremor and reduce fatigue. The instruments should be held in the tripod pinch between the thumb, the index, and the middle finger stacked upon the ring and the little fingers. As suggested by Acland, this position led to control tremor and guarantee the best handling of microsurgical instruments (Fig. 3.2) [5].

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Fig. 3.2

Correct microsurgical instrument handling


3.3 Selection of Recipient Vessels


The recipient vessels should be as long as possible to permit them to reach closer the surface and to allow adequate exposure, access, and vessel rotation. The site of anastomosis should be chosen away from branches and venous valves, at least within the segment of vessels included in the clamp. Side arterial branches and tributary veins may act as restraints causing kink or alter anastomosis position before wound closure.


The recipient vein should be selected based on its caliber (up to twice as flap vein diameter). After its division, it is advisable to check for valves near the site of anastomosis that may cause drainage resistance. This may be accomplished through direct inspection under microscope magnification or through “a flush test.” It consists in flushing the recipient vein with dilute heparinized saline through a blunt catheter in order to assess the ease of drainage. If high resistance or consistent backflow is encountered, a sacrifice of small vein segment containing the valves may be necessary. If this maneuver causes an excessive shortening of the vessel, another recipient vein should be selected. If there are no valves but high backflow is present, tying tributaries beyond the anastomosis site may represent a valid solution.


A good recipient artery should show a valid pulsation after its dissection, and a consistent spurt should to be present after its section. It is of paramount importance to not manipulate the artery excessively in order to not cause a spasm. The vessels have always to be handled by holding the adventitia and never by grasping the wall directly. During the dissection, it is useful to bath the vessel with warm saline, and if necessary and when a spasm is detected, irrigation with vasodilatation agents (papaverine 3%) may represent a good option (Fig. 3.3).

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Fig. 3.3

Vessel preparation


3.3.1 Pedicle and Recipient Vessel Preparation


In order to perform a correct anastomosis, the two vessel ends are to lie in the same plane and kept well approximated without tension. The choice of the best clamp to be used is based on vessel diameter and vessel wall characteristics (A vs. V clamp). The V clamps are usually used for both artery and veins, but in case of a slippery vessels, the A clamps are needed. In applying the clumps, particular attention is to be paid to not snap the clamp onto the vessels (Fig. 3.4).

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Fig. 3.4

Microsurgical clamps


Before performing the anastomosis, adventitia need to be stripped. Fine trimming is required in order to clear see the vessel end and to prevent clot formation. The amount of adventitia removed should be extended up to 3–4 mm from the vessel ends. The procedure for the fine adventitia trimming follows three simple rules: grasp, pull, and cut. First of all, under high microscope magnification, the cleavage plane between the adventitia and tunica media is recognized. After that, the adventitia is grasped with Jeweler’s forceps, pulled longitudinally, and cut with adventitia scissors (Fig. 3.5).

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Fig. 3.5

Adventitia cutting


Vessels are irrigated with heparinized saline through a blunt catheter in order to flush out the residual blood inside the lumen between the clumps. Background material could be useful in performing the anastomosis (Fig. 3.6).

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Fig. 3.6

Background material positioning


3.4 Vessel Anastomosis


3.4.1 General Principles


The outcome of a microvascular anastomosis relies on specific steps that have to be strictly followed and taken into consideration. These steps can be summarized as follow:



  • Tie the knots with adequate tension in order to prevent stenosis and prevent leakage.



  • Place the smallest number of sutures to achieve a leakproof anastomosis.



  • Position the knots at equal distance apart.



  • The bites on both sides must be equal, and the needle should cross exactly in a straight line.

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Apr 26, 2020 | Posted by in OTOLARYNGOLOGY | Comments Off on Techniques

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