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Proximal to Distal PICA Bypass for Calcified Fusiform Aneurysm

November 28, 2018

Transcript

This video describes the technique of Proximal to Distal PICA End-to-Side Anastomosis. This is a 58 year-old female who presented with an incidental partially calcified distal PICA aneurysm. CT angiogram demonstrated the obvious presence of the calcium around the base of the aneurysm. The location of the aneurysm relative to the foramen magnum is apparent. Only a suboccipital craniotomy is necessary. And a semi-laminectomy would not be needed. Let's go ahead and review the angiogram in this case. The 3D reconstruction angiogram demonstrates the morphology of the aneurysm. In other words, it's fusiform nature compared to the ranching vessels. This fusiform feature of this aneurysm, as well as was the calcium at its base, prevent any primary clip ligation of the aneurysm. And therefore, a revascularization technique would be necessary. Patient was placed in the prone position. As you can see here, the head of the patient's slightly below the body of the patient. The neck slightly flexed. Therefore I can sit during the microsurgical part of the operation. This facilitates greatly the stability of the hand and the arms during performance of the anastomosis. If the head is left much higher or slightly higher than the body, often that a surgeon is unable to sit during the microsurgical part of the operation, due to the distance of the head from the floor of the operating room. A linear incision, obviously is more than adequate. And again semi-laminectomy would not be needed, in this case. After suboccipital craniotomy was completed. Here's the C1 lamina, at the tip of my arrow. The arachnoid was gently torn apart. This is an efficient way to open the arachnoid in this case. Using jeweler forceps. The aneurism is immediately apparent underneath the right tonsil. You can see this feeding artery, the fusiform nature of the aneurysm and the presence of the calcium in it's space. Small part of tonsil was removed in order to expose the aneurysm and the surrounding normal vasculature. Let's go ahead and expose the distal part first the aneurysm is delineated from the fourth ventricle. Here, you can see part of the aneurysm is embedded in the fourth ventricle. This is an important part of the operation in terms of understanding the configuration of the feeding artery and the exiting artery. Here, you can see the exiting artery has a very short segment before it bifurcates. And therefore a primary anastomosis from the proximal PICA to distal PICA and excluding the aneurysm was not technically feasible. However, this branch of the distal PICA was readily in the vicinity of the proximal PICA. And I felt that an end-to-side anastomosis would be possible even though there's a slight caliber difference here. So the plan was essentially to occlude both vessels. You can see a branch of the distal PICA. There is another branch here. This is the exiting short artery out of aneurysm. And therefore connect, or revascularized the distal branch here from the proximal segment of the PICA. Let's go ahead and see if this is feasible. And you can appreciate the short exiting artery from the aneurysm. I use a papaverine soap gel foamed to bathe the vessels in papaverine and relieve their vasospasm. Here again, you can see the configuration of the exiting artery. Here's the quad plexus on the aneurysm and the floor of the fourth ventricle And as the floor has to be carefully protected and kept clean. Here's the proximal PICA. 11th cranial nerve. Want to see if there are any perforating vessels at the level of the more distal PICA. Here, you can see a large perforating vessel just proximal to the entry of the vessel into the aneurysm. This vessel has to be carefully protected. I first tried to untethered these important perforators. So have additional length for placement of a temporary clip. Again here is the floor of the fourth ventricle. Again, the medial wall of the aneurysm. The floor of fourth ventricle, here. Let's go ahead and start the process of the arteriotomy, on the distal PICA. Here, you can see temporary clip just distal to that large perforator. Here is another temporary clip on the distal PICA. Now the distal PICA is excluded. I'll go ahead and transect the more proximal section of the PICA, sharply, from the aneurysm. This section of the proximal PICA is mobilized toward the distal PICA. And then end-to-side anastomosis, appears to be feasible. You can see the large important perforating artery is being fed. I tried to mobilize this artery to create more space. Now the arteriotomy was completed on to the distal PICA. The lumen is clearly exposed. Arteriotomy is extended on both sides of the initial cut. The first stitch, in this case at 9/0 or 10/0 suture would be adequate. I decided on using a 9/O suture due to the size of the caliber of the vessels. First suture should be from outside to inside, inside to outside. So the knot is kept outside of the lumen of the anastomosis. Here's the heel of the anastomosis. Next another sutures placed at the toe of anastomosis. Again, from outside to inside and inside to outside to keep the knot outside the lumen of the vessel. I turn my hands so that the suture does not tear through the wall of the vessel. The first suture line would be intraluminal. This is rather challenging. Specially at the depth of operative field within the posterior fossa. One has to be very careful not to catch the front wall of the vessels and continue along the back wall intraluminally. Also, since this is a running suture, three or four sutures would be more than adequate to create a good seal and anastomosis site. And you can see isolation of the back wall turning up the hand movement of the needle in segments so that the needle will not tear through the wall of the vessels. As mentioned at the beginning of the video, the sitting position of the surgeon is quite important for performance of this anastomosis to keep the hands steady and on target. Let's go ahead and put the fourth suture in this case, which is completed now. And the residual stump of the initial suture at the heel of the anastomosis is used to tie off this suture. And the knot is kept outside the lumen. Similar technique is used on the front end of the anastomosis. One has to be careful not to catch the back wall of the proximal PICA. This anastomosis is technically much easier because it's extraluminal. But one has to be again, very careful to catch the front walls of the vessels. The final knot is also completed to the toe suture. Remove the distal temporary clip. You can see back flow through the aneurysm. I'll go ahead and place a permanent curved clip on the aneurysm distal section, connecting to the draining artery to avoid the back flow into the aneurysm. Either temporary clips are sequentially removed. Not much bleeding is apparent at the anastomosis site. Micro Doppler confirms good flow. Let's go ahead and do fluorescein angiography. Adequate flow through all the vessels are apparent. The aneurysm is no longer filling. You can see there's no blood within the fourth ventricle. It's still remains clean. You can I see the perforating vessel to the floor of the fourth ventricle is irrigating well. Again papaverine soap gel foam is used to relieve vasospasm from the vessels. The depth of dissection is quite deep. As apparent here. Closure was completed in standard fashion. Postoperative angiogram demonstrates good filling across the anastomosis. There is no evidence of stenosis or lack of distal filling, in this case. And you can see nice distal filling of distal PICA aneurysms. And the postoperative CT scan reveals no evidence of ischemia. And this patient made an excellent recovery after surgery. Thank you.

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