Magnetic resonance imaging reveals edema-like changes not only subcutaneously, but also in muscle tissue after femoropopliteal bypass surgery.

Background: The pathophysiological mechanisms that induce postrevascularization edema after femoropopliteal bypass surgery are not completely understood. Reperfusion-associated injury to revascularized tissue and damage to lymphatic structures are both likely to play a role. Aim of this study was to study edema formation after peripheral bypass surgery with magnetic resonance imaging.

Materials And Methods: Nine patients suffering from severe peripheral arterial occlusive disease were subjected to magnetic resonance imaging scans before and 1 week after autologous femoropopliteal or femorocrural bypass surgery.

Results: A 12% increase in volume of the upper legs and an 11% increase in volume of the lower legs were measured in patients postoperatively. The increase of volume was largely due to expansion of the subcutaneous compartments: a 35% increase in the upper legs and a 41% increase in the lower legs. Edema in the upper legs was predominantly located medially at the site of the surgical wound. In contrast, edema in the lower legs was homogenously distributed around the entire leg circumference. The muscle compartment showed no significant change of volume. However, in the majority of patients, edema-like changes were seen in selected muscles as well after a peripheral bypass reconstruction.

Conclusion: Swelling of the subcutaneous compartments is mainly responsible for the volume increases in upper and lower legs similar to lymphatic edema. In addition, in a majority of patients, edema-like changes in selected muscles were seen especially in the upper legs. Reperfusion-associated injury as a cause of these changes cannot be ruled out.