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  • Introduction
  • 1. Isolate and Transect Artery
  • 2. Suture Front Arterial Wall
  • 3. Suture Front Back Wall
  • 4. Test Anastomosis
  • Discussion
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Microsurgical Technique for 1mm Vessel End to End Anastomosis


Yelena Akelina, DVM
Columbia University Microsurgery Research and Training Laboratory



Hello, I am Dr. Yelena Akelina. I'm a DVM, and I work here as a research scientist and instructor of clinical microsurgery at the department of orthopedic surgery at Columbia University Medical Center. We're here in the Microsurgery Research and Training Laboratory, which was founded by Dr. Harold Dick, 40 years ago and now is one of the prominent centers on teaching microsurgery around the world. We're going to present to you the main exercise that we teach here, which is end-to-end arterial anastomosis, utilizing this microscope and rat femoral artery, which is 1 mm diameter. So anastomosis is a connection of a tube. So a tube can be vessel, could be nerve, could be vas, could be a tube of the uterus. So it could be anything that needs to be connected - could be even be intestinal anastomosis. So something that when you connect two ends of a tube, they call anastomosis. So performing microsurgery, if you can do this small vessel under microscope, you can do pretty much everything that needs to be connected - two ends together.

The summary of the exercise that you're about to see is - starts with incision on the skin in the inguinal area of the rat. Then we're going to raise the fat pad, and - to see the femoral bundle - and we're going to isolate artery from the vein and the nerve. Then we're going to ligate the muscular branches that lies beyond the vessel. We're going to cauterize it as well. Then we're going to clamp the vessel, putting background underneath of the vessel to protect the vein, and we're going to transect the artery in the middle. We're going to trim adventitia, dilate the vessel ends, then bring the clamps closer together, and we're going to start suturing. We're going to put two stay sutures at the corners, as 12 o'clock and 6 o'clock, and we're going to tie them to the frame to have some tension. And then we're going to put middle stitch and two stitches in between the stays and the middle stitch. We're going to flip the clamp over and do the same procedure on the back. So the anastomosis will include about 8 stitches altogether.

After it's all done, the stays will be removed. The clamp will be opened from the distal point to the proximal point. The fat pad will be applied as a hemostatic tube, and the gauze will be applied after that. So we're going to have the vessel recover for a couple of minutes. Then we're going to assess the patency, which we're going lift the vessel up and see if the blood going through it and we see the good pulse. So those are the steps of pretty much every anastomosis you're going to perform.


So we're going to start dissecting the vessels. This is where you want higher magnification. That's about 20 - let's say 26 times mag, and you should see the vessels pretty clear. And especially your pickups - your forceps, which are very important to see. Otherwise, you create a lot of damage. So what we do now - first, we create a little window, between - in the perivascular sheath to see to separate artery from the vein, which is very important. Okay, you can use the hydrodissection at this point, which is useful too. We can - in this little vid - window, we can just push a little saline or lidocaine, and it magnifies the view. So you see, you can see much better the distance between the vessels. So I'm going to zoom closer, and if you notice, when the right - when I dissect, I don't touch any vein or artery walls.

So with the vessels are isolated between each other, we can look at the muscular branches, which we would need to isolate and ligate and coagulate. You can also notice how I handled the vessel by adventitia. So you will never grab the vessel by its wall. You will create irreparable damage in the lumen. So this is the branches that we going to ligate and coagulate. We call them Murphy branch, and we're going to just put the ligature around it with stenonylon and bipole it. If you notice, I u - use constant magnification in and out, which is very important part of this - taking this course - so the people learn how to use the microscope correctly.

Also, what I also want to mention that I didn't mention before - the right magnifi - for focalization of the microscope in the very beginning. So I'm going to mention it right now, and I just like getting - so initially, when you're focusing the microscope, you should be on the highest magnification possible and adjust your focus on there. This way, every time you zoom in and zoom out, you will be focused. So it goes like that. You zoom all the way in, adjust your focus here, and then from there, you can zoom in and zoom out, and you will stay focused. This is very important point in our training called for focalization of the scope.

So at this point, I ligated the branch. I'm going to coagulate that with a bipolar coagulator, which is basically jeweler's forceps. So the main point - you always have to know that you don't touch anything else. So you have a very good grip on the vessel. And you go strictly perpendicular, and you just touch. And that's it. That's all you've done. So this is a safe way to coagulate any vessel. So - and the reason why we ligate that is so you stay away from the main branch of the vessel so you won't hurt it. It's pretty small and very fragile. Okay.

So this vessel is all isolated. You can see it's all free. We're going to put drop of lidocaine solution. It's 2% lidocaine, and it just opens up the vessel before we clamp it so it won't create any troubles while you're suturing.

We're going to use a double clamp with a frame around it. We're going to have a background for the better visualization, protection of the vein, and we're going to have a double clamp here. So our vessels - so before you clamp it, you really have to assess where you want to go, and the reason - the main reason is your location of your branch. So this branch is pretty proximal, so we'll leave it untouched. We're just going to clamp this way here, and cut it in the middle. So, you open the clamp, and put the vessel right in - pretty much on the tip of the clamp. Have a little slack. Clamp it second time. And this is your second. And this is your vessel clamp. So, we're going to transect it now. And wash the blood with a very - 30-gauge - tiny - interior chamber cannula with 30-gauge needle and heparinized saline. So we basically just wash it off immediately so the blood will not coagulate inside. Okay.


The next step in preparation of the vessel edges are trimming adventitia. And if you noticed, I put a lot of water in the field, which is very important, and you'll see why. So when we're pulling and we’re trimming adventitia in - under water, you can visualize it much better. You see? You can see where the lumen is and where the adventitia. When the vessel is dry, you can’t really do this. So pulling it forward, slide adventitia off the edge, and just cut this - these small cuts. The trick is here - is hold the scissors strictly parallel to the surface you’re cutting from, which is very important so you will not nick the vessel accidentally. And sometimes you can use - you see, you can tease adventitia away with very gentle strokes and use the blade - or with scissors - so you can cut it right away.

Make sure nothing floats in your field so it's not going to float inside the vessel. So that's about it. So you only need suture line trimming. So that's not really much. You can also do this; you can rotate the vessel on a clamp. Going to zoom out a little bit so you can see better. There’s this way you can trim. You can still trim this way, which I prefer. Okay, so this is adventitia trim from both vessels’ edges, and we're going to dilate the vessel now.

I'm going to bring the vessel dilator in, which is this small and very blunt instrument - very delicate instrument, and I'm going to dilate this vessel’s edges a few times. Because our arterial anastomosis already has a smooth muscle in it, it's just much easier to dilate that so it basically stands up better. Then you switch your hands so you have a good control of this instrument, and you dilate it again - a couple of times. So the vessel is all nice and dilated. That's all. Okay. And now we're all ready to bring the clamps closer and start suturing.

So I'm going to use two hands and one instrument, which is angled jeweler’s forceps, and I'm going to have this motions, which are very, which have to be very gentle, but it has you-gives you much more power over this instrument, to bring the clamps together. So basically, we're going to slide the clamps closer together. So I'm going to do it like that. You can sometimes apply one - a teeth on one - on a frame, another one on a clamp - so you have control. So I prefer this way than two jeweler’s. This has proven to be much safer way. So now this vessel is ready to be sutured.

Alright, so what I'm - what I’m going to do - I'm going to put two single stitches - it's all interrupted. So we're going to put two stays - 12 and 6 - then one middle stitch and one on each side of it. So the whole vessel will be sutured with 8 interrupted, 10-0 nylon sutures. So if you noticed, I handled the stitch by the suture, make it sit, and just go grab it. And you have 90-degree angle needle through the needle holder and 90-degree angle needle through the cut. Now we're going to zoom in, and we're going to do two stays. And you're gonna watch me - how I'm handling the vessel with the tip of the needle, which is very important. So you see, you can use the needle as a hook and get the pickups inside. And what - what the pickups does - the trick with jeweler’s - is has two functions: first it separates front and back walls, and also it supports the needle.

Okay. So what we're going to do - there is a trick. So twelve o'clock stitch for me it’s right here. So I'm going to grab the twelve o'clock stitch, rotate it slightly, and go between the teeth. And see, I'm supporting the needle with my metal. And then zoom a little bit out. Very gently, I'm going to grab this needle out. We grab it, right there. Zoom back up. And if you notice, this stitch is very small and through the lumen. And you can see the lumen pretty well here, and you're just going to grab the twelve o'clock here, push it through, and pick it up. So I'm going to use the regular square nuts. Can zoom a little bit closer. And we're going to have a pretty long loop, which is much easier to use - so you don't have to re-grab it again. And I'm going to use a regular sk - single square nut.

So I'm going to tie - this is our first stay, which is twelve o'clock from me, and I'm going to secure it on the frame. So I'm going to put it like a figure eight motion around this positions on the frame, so it's over the middle on the low post and the high post - and it's tight. So this basically will, as I said, gonna simulate the person who is going to hold. If you don't have a frame in the operating room, you're going to have a - just a bar and two singles. So you have some other surgeon who is helping you and holding the stay for you. So this is just - instead of that, we have this frame. So instruments are very important to hold correctly. So we recommend to use a pencil grip hold. So it's like you will hold you pen when you write, and your hands are great if they are on some kind of support. So you don't really need to use neither of the muscle on the arm - just the finger motions, okay?

Okay, so I'm going to zoom back up, and I'm going to take another stitch. And that's going to be six o'clock now. I'm going to use my needle again to intro - to introduce my forcep. I actually like rotating the forceps a little bit towards me, clockwise, and I'm going to introduce it this way. So this way, it's easier to see the six o'clock stitch - or you can do this rotating maneuver that I used before. So again, you take - it's quite a big bite. I'm going to do it again and do a much smaller bite. So the bites in microsurgery should be one or two diameters of the needle from the edge, which is - comes with practice. So now, I can push it in, release the needle, zoom out a tiny bit to re-grab it. Economy of motion is another stick - strict of microsurgery - and another six o'clock I can see here, which is pretty straightforward. You pus it - push it forward and do it with a needle holder.

So now we're going to tie the six o'clock stitch. So surface tension is another big problem in microsurgery, working under microscope, so you have learn how to deal with it also. I'm zooming in a little bit higher, and - so you can see better. Three square nuts. And if you noticed, I have pretty long loops, and I didn't have to re-grab it. So just saving you time. So I'm going to trim my short end. Okay, good, so we're gonna tie the six o'clock stay on the frame - put some tension on it - and we're going to trim the suture off now. So we're all ready for the middle stitches.

So again, I'm going to put the pickups of the tip - tips of the pickups inside the lumen to separate front and back and take a small bite and go between the teeth. And then I'm going to look for the back wall - see it's there - and just take a small bite, lift up on the tip of my needle, and push the needle through.

So what I'm going to do now - I'm going to flip the clamp over. Even if we saw the back wall, I'm going to show you how to flip the clamp safe way. So these two close instruments - the frame goes up and rotates, and then zoom in and what you need to see - you need to see both walls are wide open, and we have that. Okay. So we nicely divided the vessel in halves. And then we're going to flip the clamp back over, and we're going to tie this middle stitch. Again, using as very few motions as possible.

The jeweler's forceps, if you noticed, work on the very tip. So you have to really grab the very tip of the stitch to have a good grip. Three square nuts. Nice and easy. If you see, we don't use any power, so it's good to have light hands with gentle touch when you're tying, which, again, you learn with experience. And we're going to trim. And now we're gonna dissect - I'm sorry - we're going to bisect these distances between the stays and the middle stitch, so we have to put two more stitches in this area so that - if I - you noticed, I left this longer, so we're going to tug on it. The way to avoid the front wall from the back - we're going to lift it a little bit and take smaller bites. We're going to put two more stitches in it. So you see, I am lifting the wall up and also playing with the tip of my needle to lift up my lumen. Just trying to secure my needle so it don’t get stuck.

Okay. Going to zoom out. We're going to pull the needle again through, gently. Before I tie it, I just want to make sure that we didn't catch the back. And again, I flip it, gently. Zoom closer so you can see the both walls. Ah, good! We see the mistake. So it grabbed a little bit. And it's good to see it. It actually could be probably just ripped away, but we're going to replace this stitch. Oh good. I will. I like when people do mistakes here so they can actually see what they've done wrong, but it's also good to check. So we'll do this stitch again. Going to do tiny little bites now. Okay, I’m going to zoom out at some point. Try again. Yes, and we got it this time. So the wall is completely free. So we're going to do this for all of the front wall stitches. Okay. Three square nuts. And we're all done with the front. We're going to trim all of the unnecessary stitches here. And we're going to flip the vessel in the back.


So we're going to complete the back wall now. Using the same maneuver, you're going to use the needle to hook it up. Put the pickups in. Take a small bite. With the support of you jeweler's forceps, lift it up - with the tip of the needle, too - and push it through. And you try to push it a little longer, so you can pick it up. Now you can zoom out. Pull the needle through and tie the same square knots. Again, I lift a little longer short end, so we can use that for the tagging and elevating the wall to avoid the back wall because there's no way for us to check anymore if the front wall is closed. So I'm going to zoom all the way up. And - where is it? And I'm going to put small bites, and actually I can visualize that I'm not through the back. You see, when I'm doing this maneuver with the tip of my needle, I know that nothing attaches to that, so that gives you a field that is free. And zoom out to see better and be safer. Pull this away so you won't tie it into your stitch. So these little details are very important. So people observe those to be successful. Okay. Gonna cut. And that's the last stitch we're going to put on the other side, and then anastomosis is completed. See I'm lifting it up so you - oh, I'm lifting the wall up, and again, I'm doing this maneuver with the tip of my needle. Push it through, pick it up, and zoom out. Sometimes the short end is not easy to catch. So you will try to put it somewhere where it's a little bit easier - so like off the clamp. And if you see, if you have the long loop, the only thing you do is just tie.

Okay, so I'm going to trim all the stitches that I don't need, and we're going to flip the clamp over. So I'm going to zoom out. I'm going to flip the clamp over to a natural position. We're going to cut the stays - both of them. So don't forget that. You can examine the anastomosis just before you let go so you can see nothing gets stuck - you don't have any gaps. So yeah, I think it's pretty well done. And - looks good.


So we're going to zoom all the way out, and we're going to remove the clamp. I'm going to free up my fat pad, which I'm going to use for the hemostasis. We're going to bring it up. And I'm going to remove the distal clamp first, which is the low blood pressure side, and it's going to bleed a little. I'm going to remove the blue background, and we're going to do distal, then the proximal, then put the fat pad and some gauze. And we're going to give the vessel a chance to recover and assess the patency. Here we go. So the distal is up. The proximal is up. That’s the fat pad on it - and some gauze.

Okay, so now we see - so I just removed the fat pad, and this is our anastomosis. So this is on the lower magnification. This is about probably 3-and-a-half loops. This is the lower point. And you can see how small the vessel is. So this is tip of the jeweler's, which is .2 mm. So this is really small. It's one millimeter diameter. Now, I'm going to zoom up a little bit, and we're going to see the distal pulse. So assessing the patency - that's another point, which are important. So what we're going to do - I'm going to put the jeweler's - angled jeweler's forceps - underneath of the anastomosis, and we should see the pumping blood coming through. See that? So the blood from here - the pulse on the proximal end, which is not injured - has to be exactly the same as post-anastomosis, and it is. So it's a nice pumping vessel. You can put a little bit of lidocaine just to release the spasm from the clamps for a couple of seconds.

And we can say this anastomosis is completely sutured. It's ver - it’s patent. There is also a patency test where you squeeze the blood coming through. It's pretty traumatic for the vessel - we're not recommending doing it all the time, but if you have any doubts - so you're basically occluding the blood post-anastomosis and milk it, distally - and you open it. So, it should be no time at all lapsed through - from the occlusion to the opening. You see, that's exactly what it is. Okay, so this is our patent arterial, end-to-end anastomosis on 1 mm diameter vessel. There we go.


I've been teaching microvascular surgery in this institution for the last seventeen years. We teach about 200 surgeons a year from about twelve specialties, about 45 programs from US, and about 50 countries around the world. So people coming here to learn this very specific and difficult skill. Because it's a small lab - it's only three students and one instructor, which is a pretty good ratio for one-on-one training for, again, very difficult skill.

There is a lot of mistakes done in this course. And the most common is ability - no ability to focus the microscope correctly and use the machine in the right way. Then, people are sometimes rushing through the anastomosis a little bit too fast, and they're doing mistakes by just not observing the hands too much. Another one - people do a lot of back wall stitches when they're catching posterior wall with the stitches and the veresult - will result in a failure as well. There is spacing issues - the distance between the stitches is very important - that we teach people doing very common mistakes that it's not spaced enough, so it causes a lot of bleeding. So that's the most common ones.

And by doing this courses the people are actually learning what mistakes can be done here in an environment like this - in a lab - instead of doing this in a human OR. So they do this, they recognize that, and they're learning how to fix that. So which is - I think most important part of the teaching here that the people have space to do these kinds of things. And mistakes are done here and learned how to fix and not repeat again results in much better surgery outcomes in ORs. That's one of our goals to teach here - that people are dealing with troubleshooting with the control of us - with the - by the instructors, which will help them to resolve these problems.

Rats' vessels are fresh and young - young and healthy, so they’re doing a pretty fine job because they're also very thin. People who operate - well, surgeons who operate on humans - usually dealing with atreskis - arteriosclerosis, and it makes the vessel much thicker. So, you know, they actually have to go through the vessels much more - with much more force than we teach here. So for us, it teach microvascular surgery on a healthy, very thin vessel is better, so they can also do much thicker vessels. So this is not really related as well - so rats are not arteriosclerotic or old or thick. So - but it's pretty tough as it is as the skill to teach and to learn as well. So it's enough complication to just learning it on a fresh, healthy vessel. So it's enough complication to just learning it on a - on a fresh, healthy vessel.

So I'm a third-year resident. Currently, I'm interested into going into sports medicine, and all residents who come through this program have to spend at least a week in the microvascular lab, learning how to suture small vessels and nerves. And before coming to lab, I had no experience with this. After leaving it, I have an appreciation of handling of small vessels and just a great respect for what micro - microsurgeons do. I think it's going to be helpful in my 3D spatial visualization, which is also very important in all sorts of orthopedic surgery, and just handling tissue in general - I think my thought process and perception of it has changed a lot after being in the lab for five days.

Now, I want to state one statement, which is very important for me, and I have been talking a lot about this at all international conferences: that I truly believe that quality of the surgical training will increase significantly if programs will implement courses like this. So if person - if surgeon even never touch a microscope in his career - has sports surgery or general surgeon, doing the courses like this gives them a lot more skills that they - they becoming a better surgeons as they are before - they were before. So it's very important. So I really truly believe that courses like this should be everywhere, and people will take it and become a better surgeon. So our quality of surgical care will improve significantly. And that's why - the reason why is important because doing these courses people learn, first of all, gentleness. Handling, dissecting the small tissues like this on 1 mm diameter or smaller - you have to be gentle. You can't do otherwise. People are learning how to coordinate their hands and eyes and feet and hopefully brain together to have a surgery done with assistance of the foot-pedal-controlled microscope.

Also, by planning procedures, they're learning how the preparation and set up is very important. Paying attention to little details - this is what microsurgery is all about. If you don't pay attention, you won't be successful. Also, they're learning how to self-control themselves, and the patience here is the key. If you're not patient, if you - it is frustrating, but if you're not patient enough and you have no self-control, you won't be successful. So the quality like this, I agree, and I think everybody will agree, are important to every surgeon - no matter if he will never touch microscope again. So this is, I think, very important to have courses like that.