Vein graft intervention

As the number of individuals in the society with saphenous vein grafts to coronary arteries are increasing, the need for vein graft interventions are on the rise. Vein graft lesions could be either in the aortic ostium, body of the graft or at the distal anastamotic site. Vein graft degeneration and stenosis are much more common than loss of function of the left internal mammary artery grafts for which long term patency rates are much higher. Interventions in degenerated vein grafts are riskier and results often suboptimal than native vessel angioplasty. Unlike in native vessels, opening up a total occlusion is seldom attempted in case of vein graft lesion. In such situations, it will be better to attempt opening up the native vessel if feasible. A totally occluded vein graft is likely to be thrombus laden and cause significant distal embolisation. The chance for distal embolisation is high even for subtotal lesions and hence the use of distal protection devices is the standard of care in vein graft intervention.
Special catheters (both diagnostic and guide) are available for vein graft interventions. Cannulating grafts near the left coronary ostium may be more difficult than those near the right coronary ostium. After the initial diagnostic shots, the lesion is crossed with a guide wire (primary guide wire). Once the primary guide wire is in situ, a distal protection device which is mounted on guide wire is threaded over the primary wire. Once the filter device with sheath has crossed the lesion and placed well beyond it, the primary guide wire is withdrawn. After final check shots, the filter is deployed by withdrawing its sleeve. Predilatation before passing the filter is avoided as far as possible and so are attempts at forcible movement of the filter across the lesion for fear of distal embolisation. Once the filter is fully deployed, the predilatation balloon is threaded over the guide wire of the filter device. After adequate predilatation, the stent is deployed at the nominal pressures. Over inflation and post dilatation are avoided for safety reasons. After check shots, the stent balloon is removed and the filter sleeve re introduced and passed distally to cover the filter before final withdrawl of the filter.

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