*3.6.1 Getting the arterial defect ready*

*The Current Perspectives on Coronary Artery Bypass Grafting*

damage to the intimal walls kicks off the cascade.

Repairing a vein is not for the novice and is much harder than an artery. The most obvious reason for this is that the walls are floppy and much thinner, so it is difficult to see the edge after dissection. The other reason is that veins have less adventitial tissue that is rather adherent to its walls, making it challenging to dissect. They are hence also easier to damage unless handled with meticulous care and technique. Last but not least, the slower blood flow makes them prone to thrombosis and even slight

The vascular sheath is flimsy but adherent. Pick it up (making sure one does not damage the venular wall) with a good pair of jeweller's forceps and holding the dissecting (blunt) micro-scissors parallel to the vein, make a hole in it. Then slide the scissors into the space and dissect along the wall of the vein carefully, making sure not to pull out any tributaries with force. These should be ligated with 10/0 nylon or cauterised very carefully. Once released, the vein ends are brought together and placed in the double clamp. The job is made easier if there is an underlying piece of background material and the operative field is flooded with saline or Ringer's lactate. A fine vessel dilator should be used to dilate the vein in two or three directions. It may be difficult to locate the lumen initially, but once this is done, the vein takes a more recognisable form and the lumen

In view of the thin walls, there is a tendency for the vein edge to roll inwards and mistakes can be made in taking stitches. Extra precaution should be exercised and if there is any doubt, do not proceed until it is cleared. The first two stay sutures are the most crucial and should be done while bathed in saline. The intermediate sutures may be placed slightly further apart (double the distance) than in an artery

Once the repair is complete, the **distal** clamp is released first to flood the repair site and the vessel dilates immediately. Immediate release of the proximal clamp

A good result will reveal a similar diameter and colour both proximal and distal to the anastomosis. Patency is confirmed by the uplift test. Flow is tested from distal to proximal (along the direction of flow) across the anastomotic site. If there is a block, it will bulge at the anastomotic site and the proximal diameter will be smaller, while the blood in the distal part will progressively

This procedure is more difficult than a straight-forward venous anastomosis and has multiple steps: getting the arterial defect ready, harvesting a vein for grafting using a meticulous dissection and anastomosing both ends of the graft. It is a neces-

**3.5 Venous repair: end to end**

*3.5.1 Dissection of the vein*

becomes visible.

*3.5.2 Suturing technique*

*3.5.3 Checking patency*

should show a good flow.

**3.6 Interpositional vein graft**

sary skill to acquire for all microsurgeons.

become darker.

because venous pressure is lower.

**158**

During emergency procedures and sometimes even in elective surgeries, the arterial conduit is damaged and needs replacement in part or more. This is where the interpositional vein graft comes in useful. Most times the vein can be harvested from an adjacent site (size is matched) or a distant one (saphenous in the leg). In all instances, the defect must be measured in order to be bridged. Both the arterial ends are dissected free of adventitia and clamped with single clamps in preparation to receive the vein graft.
