Microsurgical Technique for 1mm Vessel End to End Anastomosis
This article describes the technique of performing an end-to-end arterial anastomosis on a 1mm diameter rat femoral artery. Microsurgery anastomosis is a technique required for free flap transfers, transplant surgery and other surgical applications. This video article shows the microsurgical anastomosis technique in detail, covering aspects that are difficult to grasp without direct visualization. The laboratory environment is ideal tor practicing the delicate and meticulous maneuvers of microsurgery and for becoming familiar with the microscope and specialized tools involved. We hope this article will familiarize the prospective trainee prior to taking courses at our laboratory.
- Carl Zeiss OPMI MC surgical stereo microscope
- Optronics Video system
- Standard Microsurgery instruments
- 10-0 nylon sutures
History and relevance
The development of microsurgical anastomosis has allowed complex reconstructive surgical procedures including free tissue transfer grafts to cover large tissue defects, replantation of limbs, fingers, toes, and the revascularization of poorly perfused organs. The closure or coverage of large defects after trauma or tumor resection often requires free tissue transfer grafts and numerous anastomoses. Microsurgical techniques may also be used as a new approach to achieve lymphatic drainage in cases of lymphedema.
Dr. Jules Jacobson at the University of Vermont first described the use of a microscope to anastomose vessels as small as 1.4 mm in 1960. In 1963, hand surgeons at the University of Louisville, Dr. Harold Kleinert and Dr. Mort Kasdan, performed the first revascularization of a partial digital amputation. In 1964 Dr. Harry J. Buncke, working out of a lab created in his garage, successfully replanted a rabbit ear, anastomosing blood vessels 1 mm in diameter. Modern microsurgical techniques are now fundamental tools of plastic surgery, allowing soft tissue coverage and restoration of function after trauma or oncologic resections.
Healing of the anastomosis
After the anastomosis is made, it must heal and mature if it is to survive. Formation of a platelet plug is the first step in a sequence of events towards healing and maturation of a fresh anastomosis. With injury to the intima, exposed collagen triggers platelet adhesion and aggregation. This in turn activates fibrinogen, which adheres to platelets and acts to link platelets together to form a platelet plug. Fibrinogen is then converted to fibrin which strengthens the platelet plug. If the vessel walls are not damaged and the anastomosis is secure, the platelet plug disappears over the first 3 to 5 days and by day 5 the pseudointima is present. One to two weeks later the anastomotic site is covered with new endothelium.
However, if there is too much damage to the endothelium, platelet aggregation continues and after reaching a certain critical mass it will trigger a cascade of events leading to thrombus formation in the vessel. The critical period of thrombus formation in the anastomosis is the first 3-5 days of healing. If a thrombus forms and is not cleared, the anastomosis will fail.
Summary of principles involved in microsurgical anastomosis
- Vessels are prepared by debriding any areas damaged by trauma
- Remove any intravascular clots and debris and irrigate with heparinized saline
- For end to end anastomosis as is shown in this article, the ends of the two vessels should be approximately the same in size
- Vessel side branches are examined and ligated to prevent hematoma formation
- Avoid vessel tension, kinking, and twisting. If tension is excessive it is preferable to perform a vein grafting
- Standard sutures are simple, interrupted, and full-thickness. These are the standard to which all new anastomotic techniques are compared.
- After flow is established, bathe the anastomotic sites in warm irrigation and lidocaine or papaverine to relieve vasospasm
- Examine anastomoses at the end of the procedure and perform the vascular strip test to check flow. To perform the strip test:
- Gently occlude the vessel distal to the anastomosis with a microforceps and “strip” the vessel with another microforceps in the direction of flow distally from the anastomosis
- Brisk blood flow should then be observed to return across the anastomosis with a good distal pulsation when the proximal microforceps are released
The author has no financial relationship with the equipment companies mentioned in this article.
Statement of Consent
This procedure was performed according to protocols that have been reviewed and approved of by IUCUC at Columbia University.
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Table of Contents
- The rat is anesthetized with Ketamine 75mg/kg and Xylazine 5-10mg/kg given Intra-peritoneally
- The groin area is prepped and draped in a sterile fashion
- Begin by making a groin skin incision in the rat prior to using the microscope
- Dissect out and raise the fat pad laterally out of the wound with the assistance of the microscope
- Wrap the femoral fat pad in moist gauze
1. Isolate and Transect Artery
- Adjust the microscope to high magnification and dissect the femoral artery from the vein by blunt dissection using two forceps
- Isolate, ligate and coagulate the muscular branch
- Applying the background under the artery to protect the vein and set the stage for the clamping
- Clamp the artery with an approximator clamp making sure that there is enough length inside the clamp if the branch has been excised
- Transect the vessel and irrigate with heparinized saline
2. Suture Front Arterial Wall
- Trim the adventitia from the suture line to prevent it from folding inside the lumen and causing thrombosis.
- Dilate the edges and bring the clamps closer together just prior to suturing
- Suturing the Anastomosis: Using 10-0 nylon for 1mm diameter vessels, suture interrupted stitches in the following order:
- One stay suture at the 12 o’clock position and one at the 6 o’clock position to bisect the vessels
- A third stitch dividing this distance in half
- One stitch between the middle stitch and each stay suture (2 total)
- Flip to the posterior wall, place another stitch between the 12 and 6 o’clock position
- Again, apply one stitch between this middle stitch and each stay suture
- 8 stitches are usually required for a vessel of this size. The stay stitches are usually done in two equal bites, sized by two needle diameters from the edge, the rest of the stitches are usually done with a one bite stitch
- Avoid the back wall by inserting the tips of the jewelers forceps inside the lumen for the stay sutures and middle stitch and by lifting the wall up by the one of the long tale of the middle stitch while putting the rest of the stitches in
- Turn over the clamp to check on every front wall stitch prior to tying it to ensure that the stitch did not also capture the front wall
3. Suture Back Arterial Wall
- After completing the front wall, the clamp is rotated and the same technique is performed on the posterior wall
- After completion of all of 8 stitches, inspection is done by examining the gaps
- If needed extra stitches are applied
4. Test Anastomosis
- Remove the two clamps beginning with the distal clamp first
- A fat pad is applied on a top of the anastomosis for hemostasis
- Assess the patency of arterial flow by visualizing the distal pulse and performing a refill test