OBJECTIVE: Nearly 20% of patients with critical limb ischemia will not be suitable for arterial bypass due to distal small vessel occlusion, and venous arterialization of the distal venous bed might be a valuable surgical option. This study demonstrates the in-vivo microcirculatory effects of this type of intervention.

METHODS: Using intravital video microscopy, the authors studied the distal skeletal microcirculatory characteristics following venous arterialization of critical hindlimb ischemia in the rat. 25 Wistar rats underwent proximal ligation of the femoral arteries followed by venous arterialization carried out by anastomosing the saphenous vein to the femoral artery using microsurgery techniques. Microcirculatory hemodynamic conditions of the soleus muscle were observed under normal, ischemic, and arterialized conditions. Fluorescein-labeled red cells were used to measure red cell velocities (Vrbc) at the capillaries, and acridine orange injections used to stain endothelial cell nuclei to measure microcirculatory diameters, and leukocyte nuclei to measure leukocyte adhesion. Laser Doppler Perfusion (LDP) units at the distal limb were measured continuously throughout the procedure.

RESULTS: Proximal femoral arterial ligation resulted in drastic reductions in LDP and Vrbc. Following distal venous arterialization, LDP returned to an average of 41% of baseline. Vrbc returned to near baseline values in 70% of the capillaries. Flow at the capillary and venular system showed frequent reversals and great variations in velocities. Venules and venu-venular anastomoses diameters increased by 50%. There was immediate macromolecular tracer leakage and leukocyte activation was significantly increased in both ischemic and arterialized groups (15 cells vs 156 and 178 cells respectively).

CONCLUSION: Venous arterialization may provide an improvement in microcirculatory velocities but is accompanied by microcirculatory injury and dysfunction in the acute phase. These results suggest that mechanisms besides microcirculatory hemodynamics play a role in the overall picture of clinical effectivity of the procedure

Animal ; Male ; Rats, Wistar ; Saphenous Vein ; Acridine Orange ; Venules ; Ischemia ; Femoral Vein ; Leukocytes ; Hemodynamics ; Muscle, Skeletal ; Hindlimb ; Endothelial Cells

OBJECTIVE: Intimal hyperplasia (IH) remains one of the major obstacles to long term vein graft patency. IL-1B has been demonstrated to be one of the first inflammatory cytokines expressed in the rat vein graft model of IH and may be an important initiator of the sequence of events leading to the development of IH. This study was designed to establish the role of IL-1B by demonstrating the outcome of inhibiting its effects by the use of neutralizing antibodies on the development of IH in this model.

METHODS: Rat epigastric vein to femoral artery interposition grafts were treated with neutralizing antibody to IL-1B suspended in pluronic gel and harvested at the end of one week and two weeks. The amount of intimal hyperplasia was measured at the anastomotic and midgraft regions.

RESULTS: The amount of IH was less at the anastomotic and midgraft regions of the treated grafts at the end of one week (p<0.05), but did not differ significantly with the untreated group at the end of two weeks.

CONCLUSION: Neutralizing antibody to IL-1B delivered locally retarded but did not prevent the occurrence of IH in vein grafts. The initiation of the cascade of events in the development of IH is affected in a major way , but not singularly by IL-1B

Animal ; Male ; Rats ; Hyperplasia ; Antibodies, Neutralizing ; Cytokines ; Poloxamer ; Femoral Artery ; Veins ; Tunica Intima ; Interleukin-1beta ; Transplants

RATIONALE: Compression therapy has been demonstrated to be beneficial in a number of vascular conditions including chronic arterial ischemia, venous insufficiency and primary and secondary lymphedema. Its effectivity however is limited and questioned by the nature of the treatment procedure which requires that the patient be in a sitting or recumbent position while it is being administered. METHODS: The author describes the development of a boot device which provides gait-dependent intermittent compression to the ankle and calf RESULTS: In volunteer studies, the device produced a cycle of pressure changes from 15-40 mmHg at the interface. Simulated calf compression resulted in augmentation of venous flow recorded by duplex sonography at the superficial femoral vein area, indicating an improvement in venous hemodynamics with the use of the device. CONCLUSION These findings demonstrate the potential for an attractive ambulatory alternative to the commonly employed nonambulant therapies for venous insufficiency.
Hemodynamics

RATIONALE: Endoluminal grafts (EG) are a promising alternative to conventional open surgical approaches in the treatment of aneurysmal and occlusive arterial diseases. These devices generally employ metallic stents to secure the proximal and distal EG extents. However, the problem of intimal hyperplasia at the distal EG anastomotic ends similarly affect long-term outcomes as in conventional interposition grafting methods. A technique of distal EG anastomosis using handsewn endoluminal sutures is described and its effects on subsequent development of intimal hyperplasia compared with that of metallic endoluminal stents METHODS: Ten adult mongrel dogs underwent bilateral common iliac artery endoluminal grafting procedures. On one side, the distal EG anastomosis was anchored with metallic stents while on the contralateral side the distal EG was secured with endoluminal sutures. The grafts were harvested after one month and the intimal characteristics were observed using histopathological methods. RESULTS: Distal EG metallic stents and endoluminal sutures resulted in similar patency rates of 90%. The average time to deploy distal EG metallic stents was 56 seconds, while the average time to secure the distal EG anastomosis using endoluminal sutures was 3 minutes 42 seconds. Metallic stents induced the development of intimal hyperplasia to a degree greater than endoluminal sutures (316 ± 12 μm vs. 245 ± 30 μm, p<0.05), but did not affect patency. CONCLUSION Hand sewn endoluminal suture technique results in a lesser degree of intimal hyperplasia compared with that produced by endoluminal metallic stents, while the patency rates are comparable.
Stents