Critical Ischemia Of Lower Extremities Research Articles

Changes in circulating levels of vascular endothelial growth factor and vascular endothelial growth factor receptor-2 after carotid endarterectomy

It has been shown that vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2) are upregulated in severe carotid stenosis. However, it is unknown whether carotid endarterectomy (CEA) affects serum level of these molecules. We investigated changes in concentration of VEGF and VEGFR-2 in patients undergoing carotid endarterectomy. Forty-three patients with extracranial carotid stenosis (>70%), were studied. Patients with severe vertebrobasilar stenosis, recent (<1 month) vascular event (stroke, coronary infarction, arterial thromboembolism), critical ischemia of lower extremity, recent infection, autoimmune disease or malignancy were excluded from the study. Blood samples were taken before CEA and on the second post-operative day. Thirty healthy blood donors served as a control group. We used enzyme linked immuno-absorbent assay as a method for the determination of VEGF and VEGFR-2. Pre-operative levels of VEGF (371+/-42 pg/ml) and VEGFR-2 (8424+/-356 pg/ml) were significantly elevated. There was significant decrease in both VEGF (152 pg/ml) and VEGFR-2 (1297 pg/ml) after CEA, without however reaching normal values. In asymptomatic patients and in patients with a contralateral carotid stenosis of >50%, however, the observed reduction of VEGF did not reach statistical significance. On the other hand, in the same subgroups, a major decrease of VEGFR-2 values was observed. VEGF and VEGFR-2 showed a very significant increase in serum of patients with severe carotid stenosis. These pre-operative levels decreased significantly after endarterectomy, and the changes emphasize the importance of these molecules in carotid disease progression.

Pedal Branch Arterial Bypass for Limb Salvage

In patients with critical lower extremity ischemia and occlusion of the distal tibial and pedal arteries bypasses to pedal artery branches may offer the only alternative to primary amputation. The results of 22 pedal branch arterial bypasses are reported, and a review of the literature is offered. The charts of 22 patients undergoing pedal branch arterial bypass during a 12-year period were retrospectively reviewed. The results of six additional reports of this technique were also evaluated. In the present series the cumulative primary graft patency rate was 72 per cent after 2 years. The cumulative limb salvage rate during this interval was 82 per cent. Similar graft patency and limb salvage rates were obtained with the approximately 200 other bypasses of this nature as reported in six other series. Pedal branch arterial bypass offers limb salvage results that are comparable to perimalleolar and pedal artery bypasses. In patients with critical limb ischemia and occlusion of distal tibial and pedal arteries, pedal artery branches should be sought as potential outflow sites. Bypasses to these arteries result in good long-term limb salvage, improved survival, and good functional ability for amputation. Pedal artery branch bypasses are a superior alternative to primary amputation.

Percutaneous Transluminal Angioplasty for Management of Critical Ischemia in Arteries below the Knee

Percutaneous transluminal angioplasty (PTA) can be performed safely in arteries below the knee by using current coaxial catheters. This study includes 37 consecutive patients treated between March 1992 and March 1999 by PTA for limb-threatening infrageniculate occlusive artery disease. The mean duration of follow-up was 28 months. Limb salvage was achieved in 32 patients. The actuarial limb salvage rate at 2 years was 87 +/- 6%. This study shows that PTA was a viable alternative to surgical treatment for management of critical lower extremity ischemia in carefully selected patients. Limb salvage rates after PTA and conventional surgical revascularization seem comparable. Based on these findings, we recommend that PTA be attempted, whenever possible, for initial treatment of patients presenting critical, limb-threatening ischemia due to isolated or multiple stenoses of below-knee arteries.

Long-Term Results of Infrapopliteal Bypass Using Polytetrafluoroethylene and Taylor Vein Patch for Critical Lower Extremity Ischemia

Although distal anastomotic vein patch and cuff techniques have been advocated to improve the patency of lower extremity bypass grafts with polytetrafluoroethylene (PTFE), use of this approach in the infrapopliteal position remains unproven. The purpose of this study is to evaluate the results of infrapopliteal bypass grafting using PTFE and Taylor vein patch for critical lower extremity ischemia. All patients undergoing infrapopliteal bypass grafting with PTFE and Taylor vein patch for ischemic rest pain or tissue loss were identified from the vascular surgery registry. This report describes results for surgical morbidity and mortality, patency, limb salvage, and survival for procedures performed from 1993 through 1998. Forty-two infrapopliteal bypass grafts with PTFE and Taylor vein patch were placed for critical lower extremity ischemia during the 6-year period. Surgical indications were rest pain in 25 (60%) patients and ischemic tissue loss in 17 (40%). Distal arterial anastomosis included 17 (40%) anterior tibial, 10 (24%) peroneal, eight (19%) posterior tibial, and seven (17%) tibioperoneal arteries. Follow-up ranged from 1 to 52 months (mean 17 months). Life-table primary patency, secondary patency, limb salvage, and survival at 3 years were 25%, 31%, 44%, and 66%, respectively. Infrapopliteal bypass with PTFE and Taylor vein patch for critical lower extremity ischemia has poor long-term results that are comparable to those reported for PTFE without Taylor vein patch.

Flow-Mediated Dilation in Lower-Extremity Vein Grafts

Autogenous vein bypasses manifest a substantial late stenosis and occlusion rate due, at least in part, to the hostile conditions of the arterial milieu. The present study was undertaken to evaluate flow-mediated dilation (FMD)-a putative measure of endothelial health and, potentially, long-term function-in chronically implanted vein grafts performed for critical lower-extremity ischemia. Eleven patients, four men, seven women (mean age: 64 ±14 years; range: 30 to 81 years), with saphenous vein bypasses performed for critical lower-extremity ischemia a mean of 346 ±457 days previously (range: 47 to 1640 days), had their grafts studied in the resting state, following 5 minutes' tourniquet application to produce hyperemia, and following administration of nitroglycerin. Baseline and maximal postischemic brachial artery and vein graft diameters were determined ultrasonographically. An Atherosclerosis Risk Score (ARS) was calculated by assigning one point for each of six established risk factors for atherosclerosis (smoking, diabetes, hypertension, hypercholesterolemia, male gender, and age &gt;60 years). Vein graft flow and diameter increased significantly with hyperemia (20% ±23%; p=0.04, and 3% ±3%; p=0.01 by paired t-test, respectively). Mean ARS was 3.6 ±1.2 (range: 2 to 5). FMD in vein grafts correlated inversely with ARS (r=-0.66, p=0.03). Seven of the 11 vein grafts demonstrated FMD &gt;1% of baseline diameter. No differences were observed between the seven patients with “reacting” grafts and four with “non-reacting” grafts except in the mean ARS (2.9 ±0.9 vs. 4.3 ±0.5, respectively, p=0.05) and in the frequency of diabetes (33% vs. 100%; p=0.05). Chronically implanted saphenous vein grafts performed for limb-threatening ischemia exhibit FMD. FMD in vein grafts appears to be influenced adversely by concurrent atherosclerotic risk factors, and is reduced compared to FMD reported in other vessels.

26.14 Criteria for inflow and outflow reconstructions for critical lower extremity ischemia: Indications and results

New unconventional oil extraction technologies are needed because conventional technologies to extract gas and oil from oil shale or tar sands are both economically unfeasible and ecologically devastating. One technology proposed in this paper is built on long-standing proposals to explode a nuclear bomb in the heart of an oil shale deposit which in a flash causes the release of gas and oil from the oil shale. This rubble chimney will have a glassy bottom which seals the oil from sinking into the earth, thus preventing damage to the aquifer. The authors show that the equivalent of a significant atomic bomb can be achieved using conventional explosives or liquid oxygen and carbon. The computations further show that the amount of carbonous material lost in the explosion is a small price to pay for the safe in situ collection of the oil and gas. Computations show that this technology is both physically possible and economically feasible. A second approach is using the supercritical state — that exact point between liquid and gas — to extract the oil and gas from the oil shale and from the tar sands. In one configuration, the supercritical state is achieved by a sea-based configuration using the weight of water to provide sufficient pressure. A land-based alternative is a pressure well — a very deep well that similarly achieves sufficient pressure to produce the supercritical state. Supercritical carbon dioxide is frequently used in extraction using the supercritical state and the specific technology using carbon dioxide both in devices as well as in high pressure in situ. To contain the pollutants and maximize the output, a plasma tunneler heats the oil shale in situ and collects the oil and gas while the gases are contained in inflatable domes at the “worm hole” or the aperture that the earth penetration device was fed from. Other non-combustion proposals are advanced as well.

The Current Role of Profundaplasty in Complex Arterial Reconstruction

By use of direct surgical procedures, including endarterectomy and patch angioplasty, the reconstructed profunda femoris artery has been employed to treat symptoms of claudication from femoral-popliteal occlusive disease and to facilitate healing of ampu tations that spare the knee joint. As the techniques of distal arterial bypass have become more sophisticated with improved long-term patency, the role of profun daplasty has changed. Sixty-eight reconstructions of the profunda femoris artery were reviewed for 51 patients with limb-threatening ischemia (69%), claudication (28%), or infected pros thetic vascular grafts (3%). Thirty-three (49%) of the limbs had undergone 73 prior arterial reconstructions. Forty-nine patients had inflow procedures performed at the time of the profundaplasty, and 13 had concomitant reconstruction of arterial outflow. In only 6 cases was the procedure an isolated profundaplasty. Successful profun daplasty was defined as primary patency of the vascular reconstruction. By life table analysis, revascularizations utilizing profundaplasty had a primary patency of 81% at one year, 64% at two years, and 54% at four years. The series achieved a limb salvage rate of 96% at four years. Isolated profundaplasty is seldom utilized to treat critical ischemia of the lower extremity. The current role of profundaplasty places the procedure as an important adjunct to achieve long-term limb salvage and patency of complex vascular reconstructions.

Factors influencing limb salvage and survival after amputation and revascularization in patients with end-stage renal disease

Background: Critical lower-extremity ischemia in patients with end-stage renal disease is associated with high operative mortality and low rates of limb salvage. Patients and methods: The outcomes of 102 operations for lower-extremity ischemia in 77 patients with end-stage renal disease were analyzed to determine predictors of limb salvage and operative survival. Results: Patients undergoing amputation (n = 50) and revascularization (n = 52) were similar in age, cause, and duration of renal failure, and prevalence of coronary artery disease. Operative mortality was 13% in revascularized patients and 20% in amputated patients, and was caused by sepsis in 12 of the 17 deaths (71%). Limb salvage in surviving patients was 91% at 30 days and 67% at 1 year. One-year survival was 72% in both groups. Factors associated with limb loss included advanced generalized atherosclerosis, extensive tissue necrosis, failed ipsilateral bypass, and poor cardiac functional status. Overall, factors associated with mortality included failure of limb salvage procedures, hemodynamic instability, and poor cardiac functional status. Conclusions: More liberal use of primary amputation for end-stage renal disease patients with critical leg ischemia appears to be an important factor in improving both limb salvage rates and overall operative mortality.

Malperfusion of the thoracoabdominal vasculature in aortic dissection.

Ischemic damage to vital organs supplied by the thoracoabdominal aorta greatly increases the overall risk of aortic dissection. Of 320 patients operated upon for aortic dissection since 1985, 33 (10.3%) underwent operations directed at the relief of malperfusion (15/158 acute type A; 9/18 acute type B; 4/78 chronic type A; 5/66 chronic type B). Organs affected were the kidneys in 32; the bowel in 20; and the spinal cord in 1, while critical lower extremity ischemia was present in 11 patients. In total, 64 vascular areas were affected. Fenestration of the dissecting membrane with or without infrarenal grafting was the procedure performed most frequently in 25, followed by replacement of the descending or thoracoabdominal aorta in 6, and bypass grafting or direct revascularization of individual side branches in 6. Six other operations targeted at the affected organs were done. Twenty-four patients underwent one-stage operation for malperfusion; in 11, early reoperation after primary aortic repair was necessary, while 2 patients were operated electively. Ten of 33 patients died in hospital, 7 of malperfusion-induced complications. Of three late deaths, one was related to sequelae of malperfusion. We conclude that immediate diagnosis and prompt relief of malperfusion offer the best prospects for patient survival. Membrane fenestration appears to be the method of choice for treating malperfusion in most patients, and must be directed to the level of aortic and/or side branch obstruction.

Axillofemoral bypass: Outcome and hemodynamic results in high-risk patients

Aortobifemoral bypass (AoFB) is the preferred method to provide lower extremity inflow. To determine whether axillofemoral bypass (AxFB) is an acceptable alternative for high-risk patients, we reviewed our results with these two operations. Between 1985 and 1990, 29 axillobifemoral and 5 axillounifemoral bypass procedures were performed preferentially because of severe associated medical illness in patients with severe aortoiliac occlusive disease. During the same interval, 107 patients received an AoFB for pure aortoiliac occlusive disease. Nearly all patients having AxFB and AoFB were heavy smokers, and the two groups had similar rates of hypertension and angina. However, other major risk factors were more frequently found in patients undergoing AxFB. Limb-threatening ischemia was more frequent and femoral artery occlusive disease was more severe in patients having AxFB. Anastomosis to the deep femoral arteries and concomitant infrainguinal bypass were more likely to be required in patients who had AxFB. Life-table patient survival at 3 years was 35% for AxFB versus 91% for AoFB (p < 0.001). Primary patency at 3 years was 63% for AxFB versus 85% for AoFB (p = 0.032). Secondary patency was 74% for AxFB versus 94% for AoFB (p < 0.001). However, all revised grafts in both groups were patent at 36 months, and only one revised AxFB graft was an ultimate failure. Limb salvage at 3 years was 76% for AxFB versus 97% for AoFB (p = 0.065). Nineteen of the 22 patients with AxFB who died during follow-up died with patent grafts. Hemodynamic performance of AxFB and AoFB were compared. Mean preoperative ankle-brachial index was higher in AoFB (0.50) than AxFB (0.38, p < 0.001), but postoperative ankle-brachial index was much higher after AoFB (0.83) than AxFB (0.57, p < 0.001). Even after adjustment for severity of outflow disease, postoperative ankle-brachial index was much better after AoFB than AxFB. Axillofemoral bypass was performed in older higher risk patients with more severe ischemia than those in the AoFB group. Hemodynamic performance was inferior and graft failure more common after AxFB. However, AxFB provided limb salvage in all but 2 of 22 patients who have died, and no survivor has had amputation because of graft failure. Axillofemoral bypass is an acceptable but hemodynamically inferior alternative to AoFB in properly selected high-risk patients with critical lower extremity ischemia who would likely not tolerate the more durable AoFB.

Limb Salvage vs Amputation for Critical Ischemia

Since 1980, 498 patients with 627 critically ischemic legs (rest pain, gangrene, ischemic ulcer, and ankle-brachial pressure index less than 0.40) were treated with revascularization regardless of operative risk or anticipated operative difficulty. Primary amputation was performed only when no graftable distal vessels were present (14 primary amputations [2.8%]) or in neurologically impaired, hopelessly nonambulatory patients. The mortality for revascularization was 2.3%, and the median hospital stay was 11 days. During follow-up, 41 limbs (7%) required amputation, 31 after failure of revascularization and 10 despite patent revascularizations. Renal failure had an adverse influence on limb salvage (67%) because of a significantly increased requirement for amputation despite patent revascularizations. We conclude aggressive limb revascularization in patients with critical lower-extremity ischemia results in low operative morbidity and mortality and excellent long-term limb salvage. Patients with critical leg ischemia and renal failure are at higher risk for limb loss than patients without renal failure.

Prospective randomized multicenter comparison of in situ and reversed vein infrapopliteal bypasses

We have performed a prospective, randomized, multicenter study to compare in situ and reversed vein grafts for long limb salvage bypasses from the proximal thigh to an infrapopliteal artery. Three hundred eighty-four patients required an infrapopliteal bypass for critical lower extremity ischemia. Of these, 259 were excluded because a short vein bypass was performed or because the vein was considered inadequate. The remaining 125 patients had a randomized vein bypass, 63 reversed, 62 in situ. The two groups were similar with regard to risk factors, indications, graft dimensions, and outflow. Secondary patency at 30 months was similar for both techniques: reversed 67% ± 9% (±SE); in situ 69% ± 8%. For veins ≤3.0 mm in minimum distended diameter 24-month patency rates were 61% ± 22% for 12 in situ veins and 37% ± 29% for 10 reversed veins (p > 0.05). Angiographic evaluation of failing grafts revealed lesions similar in type and frequency in both types of grafts. These included focal (in situ, n = 4; reversed, n = 7) and diffuse vein hyperplasia (in situ, n = 2; reversed, n = 1), and inflow and outflow stenoses (in situ, n = 4; reversed, n = 3). The incidence of wound complications and the mortality rate were similar for the two groups. These data show no significant difference in overall patency rates for the two types of vein grafts at 212 years. Because of the poor preliminary patency of reversed vein grafts ≤3.0 mm in minimum distended diameter, we suggest the in situ method be used preferentially when such small veins are encountered. Thirty percent of patients requiring a long infrapopliteal bypass had no vein suitable for an in situ graft, although an ectopic vein bypass was feasible. Thus surgeons performing these operations should be adept at both procedures.

Changing Arterioselerotic Disease Patterns and Management Strategies in Lower-limb-Threatening Ischemia

From January 1, 1974 to December 31, 1989, we treated 2829 patients with critical lower-extremity ischemia. In the last 5 years, 13% of patients had therapeutically significant stenoses or occlusions above and below the groin, while 35% had them at two or three levels below the inguinal ligament. Unobstructed arterial flow to the distal half of the thigh was present in 26% of patients, and 16% had unobstructed flow to the upper third of the leg with occlusions of all three leg arteries distal to this point and reconstitution of some patent named artery in the lower leg or foot. In the last 2 years, 99% of all patients with a threatened limb and without severe organic mental syndrome or midfoot gangrene were amenable to revascularization by percutaneous transluminal angioplasty (PTA), arterial bypass, or a combination of the two, although some distal arteries used for bypass insertion were heavily diseased or isolated segments without an intact plantar arch. Limb salvage was achieved and maintained in more than 90% of recent patient cohorts, with a mean procedural mortality rate of 3.3%. Recent strategies that contributed to these results include (1) distal origin short vein grafts from the below-knee popliteal or tibial arteries to an ankle or foot artery (291 cases); (2) combined PTA and bypass (245 cases); (3) more distal PTA of popliteal and tibial artery stenoses (233 cases); (4) use of in situ or ectopic reversed autogenous vein for infrapopliteal bypasses, even when vein diameter was 3 to 4 mm; (5) composite-sequential femoropopliteal-distal (PTFE/vein) bypasses; (6) reintervention when a procedure thrombosed (637 cases) or was threatened by a hemodynamically significant inflow, outflow, or graft lesion (failing graft, 252 cases); (7) frequent follow-up to detect threatening lesions before graft thrombosis occurred and to permit correction of lesions by PTA (58%) or simple reoperation; and (8) unusual approaches to all infrainguinal arteries to facilitate secondary operations, despite scarring and infection. Primary major amputation rates decreased from 41% to 5% and total amputation rates decreased from 49% to 14%. Aggressive policies to save threatened limbs thus are supported.