THE FATE OF BYPASS GRAFTS TO ANGIOGRAPHICALLY OCCULT RUNOFF VESSELS DETECTED BY MAGNETIC-RESONANCE ANGIOGRAPHY

Purpose: Magnetic resonance angiography (MRA) is a noninvasive vascula r imaging technique that is more sensitive than contrast arteriography (CA) for the detection of patent distal runoff vessels. This techniqu e has facilitated performance of MRA-directed bypass procedures for pa tients who were believed not to be bypass candidates because of the ab sence of a suitable target vessel on the preoperative CA. The fate of bypasses to these angiographically occult runoff vessels is unknown, h owever, and it has been proposed that patients with angiographically o ccult runoff may have aggressive occlusive disease, rendering bypass p rocedures ultimately futile. Methods: Between April 1992 and February 1995, 212 autogenous vein infrageniculate bypasses were performed for limb-salvage indications, 22 (12%) to angiographically occult runoff v essels. Results of bypasses performed to angiographically occult vesse ls were compared with those of bypasses to CA-detected runoff vessels. Life-table analysis of graft-patency and limb-salvage rates was perfo rmed. Results: The accuracy of the MRA-predicted patency of angiograph ically occult vessels was confirmed in every case by the operative fin dings. Life-table analysis revealed no significant difference in prima ry graft patency (p > 0.05) or limb-salvage (p > 0.05) rates between p atients with bypasses to runoff vessels detected by CA compared with t hose to angiographically occult vessels seen by MRA alone. At 35 month s after surgery, the primary graft patency rate was 68% for bypasses t o CA-detected vessels and 67% for MRA-detected vessels. The limb-salva ge rate was 83% for CA-detected vessel bypass patients and 78% for pat ients with angiographically occult runoff. Conclusion: MRA can accurat ely identify patent runoff vessels not visualized by CA. Results of by passes performed to angiographically occult runoff vessels are similar to those of bypasses performed to vessels detected by CA. MRA should be performed in patients in whom CA fails to reveal runoff vessels sui table for use in a limb-salvage procedure. The greater sensitivity of MRA may facilitate successful bypass surgery and improve the overall l imb-salvage rate.