The placement of a patch to close an artery prevents primary closure leading to a significant stenosis. In the real-life situation, the choice of material lies between autogenous vein and one of the many commercially available patches. Generally speaking, if a segment of vein is available from the same operative wound or if there is any risk of infection, vein should be used. In an elective operation, for example carotid endarterectomy, a prosthetic patch will serve just as well.
When preparing a vein patch, remember to remove as much of the adventitial tissue as possible from the edge of the patch. This will avoid the risk of this layer becoming involved in the suture line and acting as a possible nidus for thrombosis formation. When cutting the patch, bear in mind the size of the artery being patched. The aim is to close the vessel without stenosis, not to create a focal dilatation.
Technique
In general, the length of arteriotomy will be two to three times the diameter of the vessel. Clearly, if a very long endarterectomy or other similar intervention has been performed, a longer incision will be needed. For this exercise open the model artery for 3 cm and excise a small ellipse of the 'vessel' wall.
Cut the patch so that the apex is rounded rather than pointed. This will avoid stenosis at the apex of the patch closure. Do not cut the patch to match the length of the arteriotomy: leave it long as this will facilitate handling during suturing.
A double-ended 5/0 Prolene suture is inserted as a single stitch at the apex of the patch from outside to in on the patch and then from inside to out at the distal end of the arteriotomy. Tie this suture with three throws in your knot and tether one end with a rubber-shod forcep (Figure 2.1).
Figure 2.1
Apex of patch tied in place
Next, pass the needle on the non-shod end through the patch and pull this tight. Once this suture has been passed through the vessel wall and again tightened, traction on the patch will lead to eversion of the edges and align the patch and artery walls for subsequent suturing.
The first two or three stitches should be inserted separately through the patch and artery to guarantee precise placement. However, once away from the apex if it can be done safely the suture can be passed through both in one pass of the needle. So that the operator gets into a rhythm which not only makes the process faster but also more precise, keep reminding yourself to push the heel of the needle through and grasp the needle ready for the next bite. Avoid unnecessary delays repositioning the needle with fingers.
As the heel of the arteriotomy is reached, cut the patch to shape. The easiest way to do this is to cut it straight across and then trim the corners off. Be careful not to cut the suture inadvertently. After passing the heel place a further two or three sutures and then put the shod on the suture and turn your attention to the other suture (Figure 2.2).
Figure 2.2
After placing a few sutures on one side, commence suturing on opposite side of the patch
Repeat the process from the toe again, taking separate bites until away from the toe and complete the suture line towards the other stitch. Tie the two ends with six to eight throws.
On completion of this exercise, it is worthwhile cutting open your patch angioplasty and inspecting it from the inside. There should be complete eversion of the patch and artery walls and no irregular surface on the luminal aspect.
