Outflow Vessels Research Articles

Infrainguinal arterial reconstruction for claudication: Is it worth the risk? An analysis of 409 procedures

Purpose: Infrainguinal reconstruction traditionally has been reserved for patients with limb-threatening ischemia. Surgery for debilitating claudication, however, has been discouraged as a result of the perceived fear of bypass graft failure, limb loss, and significant perioperative complications that may be worse than the natural history of the disease. In this study, the results of infrainguinal reconstructions for claudication performed during the past 10 years were evaluated for bypass graft patency, limb loss, and long-term survival rates. Methods: Data were collected and reviewed from the vascular registry, the office charts, and the hospital records for patients who underwent infrainguinal bypass grafting for claudication. Results: From 1987 to 1997, 409 infrainguinal reconstructions were performed for claudication (9% of all infrainguinal reconstructions in our unit). The patient population had the following demographics: 73% men, 28% with diabetes, 54% smokers, and an average age of 64 years (range, 24 to 91 years). Inflow was from the following arteries: iliac artery/graft, 10%; common femoral artery, 52%; superficial femoral artery, 19%; profunda femoris artery, 16%; and popliteal artery, 2%. The outflow vessels were the following arteries: 165 above-knee popliteal arteries (40%), 150 below-knee popliteal arteries (37%), and 94 tibial vessels (23%). The operative mortality rate was 0%, and one limb was lost in the series from distal embolization. The primary patency rates were 62%, 77%, and 86% for above-knee popliteal artery, below-knee popliteal artery, and tibial vessel reconstructions at 4 years, and the secondary patency rates were 64%, 81%, and 90%, respectively. Cumulative patient survival rates were 93% and 80% at 4 and 6 years as compared with 65% and 52%, respectively, for infrainguinal reconstructions performed for limb salvage. Conclusion: Infrainguinal arterial reconstruction for disabling claudication is a safe and durable procedure in selected patients. These data indicate that concern for limb loss, death, and limited life span of the patients with this disease may not be warranted. (J Vasc Surg 1999;29:259-69.)

Innominate artery reconstruction: over 3 decades of experience.

Symptomatic atherosclerotic occlusive disease of the innominate artery is a threatening disease pattern that offers a major challenge in achieving definitive surgical repair. To assess the evolution of treatment strategies and their outcomes for this disease, the authors undertook a review of the cumulative experience for more than 3 decades at one institution. Between 1960 and 1997, 94 patients (mean age, 62 years) underwent direct innominate artery revascularization for occlusive atherosclerotic disease to relieve neurologic (n = 85) and/or right upper extremity (n = 26) symptoms or asymptomatic critical stenosis (n = 3). The pattern of atherosclerotic involvement revealed by angiography included critical stenosis (n = 77), complete occlusion (n = 10), and moderate stenosis with plaque ulceration (n = 7). A common brachiocephalic trunk was present in five patients. Transsternal (n = 68) or transcervical (n = 4) innominate endarterectomy was performed in 72 patients and bypass grafting in 22. Forty-one patients underwent concomitant endarterectomy or bypass of innominate branches or adjacent arch vessels, and 3 had coronary bypass grafting. There were three perioperative deaths (3%), all due to cardiac causes. Postoperative morbidity included four strokes (three resolved), two myocardial infarctions, two transient ischemic attacks, and one sternal dehiscence. Follow-up ranged from 8 months to 20 years. Postoperative actuarial survival rate was 96% at 1 year, 85% at 5 years, and 67% at 10 years. Freedom from recurrence requiring reoperation was 100% at 1 year, 99% at 5 years, and 97% at 10 years. Innominate artery reconstruction is safe and durable when either endarterectomy or prosthetic bypass is used. The anatomic variation and disease distribution permit endarterectomy for most patients. The technique of innominate endarterectomy can be extended safely to outflow and adjacent vessels.

Helical CT of aorta after endoluminal stent-graft therapy: value of biphasic acquisition.

We report our prospective study evaluating biphasic helical CT of the aorta after endoluminal stent-graft placement. Biphasic helical CT scans in 95 patients with abdominal and thoracic aortic aneurysms who had undergone endoluminal stent-graft placement were reviewed. After a test bolus injection of 15 ml of contrast media at a rate of 3.5 ml/sec for the measurement of the optimal start delay, the aorta was scanned using the following parameters: collimation of 5 mm, table speed of 7 mm per rotation, tube rotation time of 0.75 sec, 120 kV, and 295 mA. A delayed helical CT scan was obtained 15 sec after the initial acquisition using the same parameters. Biphasic helical CT scans showed perigraft leakage in 45 (47%) of 95 patients. Leakage was shown only on arterial phase CT in eight patients and only on the delayed scans in three patients. In two patients, leakage shown on the delayed acquisition was retrospectively seen on the first scan. Leakage and outflow vessels were most visible on the arterial phase acquisition in 17 patients and on the second acquisition in six patients. Overall, biphasic acquisition was superior to arterial phase acquisition alone in 15 (16%) of 95 patients. The diagnostic value of biphasic helical CT is superior to arterial phase acquisition alone for the evaluation of the aorta after endoluminal stent-graft therapy.

Role of Endothelin-1/Endothelin-A receptor-mediated signaling pathway in the aortic arch patterning in mice.

The intercellular signaling mediated by endothelins and their G protein-coupled receptors has recently been shown to be essential for the normal embryonic development of subsets of neural crest cell derivatives. Endothelin-1 (ET-1) is proteolytically generated from its inactive precursor by endothelin-converting enzyme-1 (ECE-1) and acts on the endothelin-A (ETA) receptor. Genetic disruption of this ET-1/ECE-1/ETA pathway results in defects in branchial arch- derived craniofacial tissues, as well as defects in cardiac outflow and great vessel structures, which are derived from cephalic (cardiac) neural crest. In this study, in situ hybridization of ETA-/- and ECE-1(-)/- embryos with a cardiac neural crest marker, cellular retinoic acid-binding protein-1, shows that the migration of neural crest cells from the neural tube to cardiac outflow tract is not affected in these embryos. Immunostaining of an endothelial marker, platelet endothelial cell adhesion molecule CD-31, shows that the initial formation of the branchial arch arteries is not disturbed in ETA-/- or ECE-1(-)/- embryos. To visualize the subsequent patterning of arch vessels in detail, we generated ETA-/- or ECE-1(-)/- embryos that expressed an SM22alpha-lacZ marker transgene in arterial smooth muscle cells. Wholemount X-gal staining of these mutant embryos reveals that the abnormal regression and persistence of specific arch arteries results in disturbance of asymmetrical remodeling of the arch arteries. These defects include abnormal regression of arch arteries 4 and 6, enlargement of arch artery 3, and abnormal persistence of the bilateral ductus caroticus and right dorsal aorta. These abnormalities eventually lead to various types of great vessel malformations highly similar to those seen in neural crest-ablated chick embryos and human congenital cardiac defects. This study demonstrates that ET-1/ETA-mediated signaling plays an essential role in a complex process of aortic arch patterning by affecting the postmigratory cardiac neural crest cell development.

Bypass to the perigeniculate collateral vesselsA useful technique for limb salvage: Preliminary report on 22 patients

Purpose: We describe our initial experience with the use of perigeniculate vessels as outflow tracts in infrainguinal revascularizations for critical limb ischemia. Methods: Twenty-two such reconstructions were carried out in 20 patients over a 2-year period. Indications for surgery consisted of tissue loss in 9 patients and rest pain in the other 13 patients. Inflow was obtained from the femoral vessels. A variety of graft materials were used, including saphenous vein (16 patients), polytetrafluoroethylene (2 patients), composite (1 patient), and arterial homografts (3 patients). The perigeniculate vessels used were the medial sural artery to the gastrocnemius (arteria suralis) in 16 patients and the highest genicular artery (arteria genu suprema) in the other 6 patients. These vessels were approached via a medial above-the-knee popliteal-type exposure. Results: There were three postoperative deaths. Mean follow-up for the other 17 patients averaged 12 months (range, 3 to 37 months). Three grafts failed (thrombosis) during follow-up, leading to two above-the-knee amputations. One graft stenosis was treated with percutaneous angioplasty. The average postoperative increase in the ankle-brachial index was 0.20. Conclusion: These early results appear promising with a 1-year primary patency rate of 77%, assisted primary patency rate of 85%, and a limb-salvage rate of 90% according to the Kaplan-Meier life-table method. This technique is particularly useful when adequate length saphenous vein is not available, no other outflow vessels are available, or other outflow vessels are very calcified and not safely clamped. The continued study of the long-term effectiveness is warranted. (J Vasc Surg 1998;27:928-35.)

MR ANGIOGRAPHY OF THE PERIPHERAL VESSELS

MR angiography of the inflow vessels has undergone dramatic change in the past few years; the advent of ultra fast gradient echo pulse sequences combined with the gadolinium chelate bolus technique has supplanted earlier methods. However, owing to the highly variable flow velocities and inconsistent rate of vessel opacification encountered in the outflow vessels, two-dimensional time-of-flight MR angiography remains the workhorse of the distal vasculature.

Venous Doppler Ultrasound Assessment of the Parasellar Region

The purpose of this report is to present normal values for venous blood flow velocities from the parasellar region using transcranial Doppler ultrasound (2-MHz transducer) with both transtemporal and transorbital approaches and to examine the nature of previously reported low-pulsatility signals with velocities in the arterial range from this area. Forty-three subjects ranging in age from 18 to 56 years (mean ± SD, 31.9 ± 10.1 years) were examined. In all subjects, a venous signal directed away from the probe with the source lateral to the internal carotid artery siphon was detected on at least one side. A total of 72 parasellar venous signals were insonated. Signals were considered to belong to the main inflow and outflow vessels of the cavernous sinus. The mean blood flow velocity ranged from 6 to 81 cm/s (mean ± SD, 27.3 ± 17.4 cm/s). Typical transients in the Valsalva test confirmed the venous character of the signals. No significant gender, side-to-side or age dependency was observed. A separate analysis was done for venous high-velocity signals defined by a mean blood flow velocity greater than 30 cm/s. They were detected in 21 out of 43 subjects (48.9%) via a transtemporal approach and in 6 of them (14%) via the transorbital route, too. Again, no significant gender, side-to-side or age dependency was noted. In summary, we found a greater variability of venous blood flow velocities in the parasellar region compared to other basal cerebral veins, e.g. the basal vein of Rosenthal. The previously reported low-pulsatility signals with velocities in the arterial range proved to be of venous origin.

Epidural versus General Anesthesia: Does Anesthetic Management Influence Early Infrainguinal Graft Thrombosis?

A few contemporary reports have suggested that the use of epidural anesthesia may favorably influence early graft patency in patients undergoing infrainguinal revascularization. In order to test this hypothesis, we have retrospectively reviewed our experience with 303 primary femoropopliteal-tibial bypass procedures in 294 patients from January 1989 through June 1994. A total of 145 of these operations were done under epidural anesthesia (EA) and 158 under general anesthesia (GA); the demographic profiles for the patients in both of these groups were nearly identical. Thirteen patients (4.2%) died during the perioperative period (EA 3.4%, GA 5.0%; p = 0.48). Early graft thrombosis occurred in 35 patients (12%) during the same hospital admission (EA 14%, GA 9.4%; p = 0.28). There were no significant differences in the graft thrombosis rates for EA and GA with respect to surgical indications (claudication versus limb salvage), graft materials (vein versus synthetic), or the extent of revascularization (popliteal versus crural). Most graft failures appeared to be related to such conventional factors as disadvantaged outflow vessels and/or specific technical complications. Therefore, we conclude that the choice between EA and GA should continue to be made selectively on the basis of traditional anesthetic considerations.

A rational approach to ischemic and ischemic-diabetic foot reconstruction

Microsurgical techniques have been well documented to be of great use in reconstruction of post-traumatic defects of the lower extremity. The same techniques are also increasingly useful in reconstruction for chronic atherosclerotic disease of the lower extremities. Extremely small, heavily calcified vessels can be reliably reconstructed using delicate microsurgical techniques and high magnification. Additionally, revascularization followed by microsurgical free tissue transfer has proven to be a valuable alternative to amputation in patients with major soft tissue loss, or bony or tendon lesions requiring soft tissue reconstruction. Although this is an elderly population with a high number of comorbid risk factors, limb salvage can be obtained with a very low morbidity and mortality when carried out in a closely coordinated approach with the appropriate medical and surgical specialists. Microsurgical techniques have greatly expanded the number of patients that can be offered vascular reconstruction, including patients with severely calcified and tiny vessels (1 mm outflow vessels being routinely successful). Minor modifications in microsurgical technique (working with heavy calcification, presence of atherosclerotic plaques) allow these techniques to be applied to the chronic atherosclerotic and diabetic patient population, thus affording broadened horizons of reconstructive possibilities to these patients.

Patients with Diabetes and Critical Limb Ischemia Have a High Peripheral Vascular Resistance

Results of infrainguinal bypass surgery may be better in diabetic patients compared with nondiabetic patients. One important determinator of outcome in these operations is the peripheral vascular resistance (PR). The aim of the present prospective study is to evaluate whether there is a difference in PR in diabetic and nondiabetic patients with critical limb ischemia. The two patient groups (n = 11 for each) were matched for toe pressure, age, gender, and outflow vessel, PR was measured intraoperatively during infrainguinal bypass surgery by controlled infusions of autologous blood. The resistance was significantly higher in the diabetic group (p < 0.05), as compared to the nondiabetic group. Except for fibrinogen that tended to be higher in diabetics (p = 0.07), blood parameters, blood pressures and angiographic scoring of run-off were similar in both groups. This finding of higher PR in diabetic patients with critical limb ischemia compared with matched nondiabetic ischemic patients suggests that a low PR is not the reason for the positive results of infrainguinal bypass surgery in diabetic patients.

Lower Extremity Bypass for Critical Ischemia Using Synthetic Conduit and Adjuvant Vein Cuff

The use of an interposition cuff of vein placed at the distal anastomosis between synthetic bypass conduit and outflow vessel has been advocated to improve patency of lower extremity bypass grafts. Over a three-year period we have performed 43 such bypass procedures: to the above knee popliteal artery (n = 3); below knee popliteal (n = 13), and infrapopliteal arteries (n = 27). There were 20 females and 23 males having a mean age of 70 years (48-84 years). Fifteen patients were hypertensive, 15 were diabetic, and 25 had a history of tobacco use. All cases required limb salvage for rest pain (n = 25), gangrene (n = 10), or ulceration (n = 8) in the absence of suitable autologous vein. Nineteen operations followed a previous failed bypass. Patients were reviewed at six-month intervals. The operative mortality was 8% and two-year primary and secondary patency were 40% and 55%, respectively. Cumulative patency rates were better for first-time grafting procedures than for patients who had undergone previous attempts at limb salvage (60% versus 22%). Two-year limb salvage was 60%. During the same time period, two-year primary and secondary patency rates were 54% and 67%, respectively for autogenous vein. Although the numbers are small these results support the use of an adjuvant vein cuff when employing synthetic grafts. A prospective study of vein versus synthetic graft plus cuff should be undertaken.

Endovascular aortic stent-grafts: transcatheter embolization of persistent perigraft leaks.

To assess efficacy of transcatheter embolization of peri prosthetic leaks from aortic stent-grafts Eight patients with a long-standing (3-13 months) perigraft leak after stent-graft implantation underwent transcatheter embolization. Leakage was demonstrated at helical computed tomography (CT). Angiography was performed for evaluation of outflow vessels and transcatheter embolization. All patients underwent helical CT follow-up after the procedure and every 3 months. Embolization was successful in seven patients and resulted in aneurysmal sac thrombosis. A second procedure was necessary in one patient to complete occlusion of the aneurysm. No further aneurysmal growth was detected during 4-9 months follow-up. Right leg paresis was observed in one patient immediately after the procedure, but symptoms disappeared completely after 8 days. Another patient had a minor sensory deficit in the region of the right crural nerve. Transcatheter embolization of perigraft leaks appears to be an effective technique to achieve aneurysmal thrombosis.

Outcome and cost analysis after femorocrural and femoropedal grafting for critical limb ischaemia

The past decade has seen an increase in the use of distal arterial bypass grafts for treating critical lower limb ischaemia. However, this surgical policy is associated with variable results. The aims of this study were to identify factors that affect outcome and to calculate the cost of such surgical interventions. A prospective analysis of femorocrural and femoropedal bypass grafts and primary amputations was performed between June 1991 and January 1995. A consecutive series of 109 limbs with critical lower limb ischaemia underwent a bypass graft to a single crural or pedal vessel shown on either preoperative intra-arterial digital subtraction angiography or at surgical exploration. Complete data were available for all patients during follow-up which ranged from 0 to 42 (median 12) months. The factors assessed were age, sex, diabetes, pedal arch, graft material, outflow vessel, number of calf vessels, number of vessels crossing the ankle, inflow state, previous revascularization procedures and foot gangrene and tissue necrosis. Chief outcome measures were survival, knee and limb salvage, patency rates and hospital cost. The Kaplan-Meier method was used to construct life tables and the log rank test for comparison of factors. Cost was measured according to National Health Service criteria, and comparisons were made by the Mann-Whitney U test. At 36 months primary patency was 27 per cent, primary assisted patency 31 per cent and secondary patency 45 per cent; limb salvage was 54 per cent, knee salvage 73 per cent and survival 58 per cent. Significant factors in predicting outcome were graft material (P = 0.004), inflow state (P = 0.0001), number of calf vessels (P = 0.039), number of vessels crossing the ankle (P < 0.0001) and the condition of pedal vessels (P < 0.0001). Cost analysis showed that the median price for a successful bypass was 4320 pounds, that of a failed bypass leading to amputation 17,066 pounds and that of primary amputation in patients with non-reconstructable distal disease 12,730 pounds. The patency rate of femorotibial and peroneal bypass depends on the inflow state, the availability of a venous conduit, the number of calf vessels, the presence of straight flow to the foot and the presence of patent pedal vessels. These factors can help in the selection of patients for femorodistal reconstruction and may explain the wide variation in published results. The low cost of revascularization compared with amputation justifies attempted reconstruction. However, repeated attempts to reconstruct patients with severe distal disease who may benefit more from primary amputation will significantly increase the cost.

Infrainguinal arterial reconstruction with nonreversed greater saphenous vein

This study was undertaken to examine the effectiveness and the possible advantages of infrainguinal arterial reconstruction with nonreversed greater saphenous vein (NRGSV) grafts. We reviewed the results achieved with 189 consecutive NRGSV bypass procedures from July 1, 1985, to August 31, 1995, and compared them with 568 consecutive in situ greater saphenous vein (INGSV) bypass procedures completed over the same interval. NRGSV bypass procedures were performed by selecting the optimum inflow and outflow vessels and then excising the best available appropriate-length segment of greater saphenous vein. The valves were lysed with a Mills valvulotome using gentle antegrade distention with an isotonic electrolyte solution containing heparin (1000 U/500 ml) and papaverine (60 mg/500 ml). The graft was then translocated to the inflow site, where the proximal and distal anastomoses were sequentially completed, followed by a completion arteriography. Demographic and risk factor characteristics did not differ between patients who underwent NRGSV and those who underwent INGSV bypass. Compared with INGSV bypasses, NRGSV bypasses were more commonly secondary procedures (26% vs 8%; p < 0.001) and were more often performed for limb salvage indications (89% vs 68%; p < 0.001). NRGSV bypasses also had more distal inflow vessels (23% superficial femoral artery [SFA] and 28% popliteal artery [POP] vs 10% SFA and 1% POP; p < 0.001) and more distal outflow vessels (52% tibial and 22% pedal artery vs 47% tibial and 3% pedal artery; p < 0.001) than did INGSV bypasses. Despite the higher incidence of secondary bypass procedures and more distal outflow vessels in the NRGSV group, the overall results achieved at 5 years did not differ between the two groups. The 5-year primary patency rates were 65% +/- 5% for NRGSV and 72% +/- 3% for INGSV (p < 0.12), and the 5-year secondary patency rates were 74% +/- 5% and 82% +/- 2% (p < 0.08), respectively. Similarly, the 5-year limb salvage rate among bypass procedures performed for limb salvage indications did not differ for NRGSV (82% +/- 5%) and INGSV (90% +/- 2%; p < 0.06). The application of the NRGSV bypass graft preserves the INGSV's main advantage of optimal size match between artery and vein at each anastomosis, but facilitaties the tailoring of the procedure to the patients anatomy and the completion of the bypass with the shortest, best-quality conduit available. Our application of the NRGSV in a more challenging series of bypass procedures produced equivalent results to those achieved in a concurrent series of INGSV bypass procedures.

Endovascular aortounifemoral grafts and femorofemoral bypass for bilateral limb-threatening ischemia.

Although axillobifemoral bypass procedures have a lower mortality rate than aortobifemoral bypass procedures, they are limited by decreased patency, moderate hemodynamic improvement, and the need for general anesthesia. This report describes an alternative approach to bilateral aortoiliac occlusive disease using unilateral endovascular aortofemoral bypass procedures in combination with standard femorofemoral reconstructions. Seven patients who had bilateral critical ischemia and tissue necrosis in association with severe comorbid medical illnesses underwent implantation of unilateral aortofemoral endovascular grafts, which were inserted into predilated, recanalized iliac arteries. The proximal end of the endovascular graft was fixed to the distal aorta or common iliac artery with a Palmaz stent. The distal end of the graft was suture-anastomosed to the ipsilateral patent outflow vessel, and a femorofemoral bypass procedure was then performed. All endovascular grafts were successfully inserted through five occluded and two diffusely stenotic iliac arteries under either local (1), epidural (5), or general anesthesia (1). The mean thigh pulse volume recording amplitudes increased from 9 +/- 3 mm to 30 +/- 7 mm and from 6 +/- 2 mm to 26 +/- 4 mm ipsilateral and contralateral to the aortofemoral graft insertion, respectively. In all cases the symptoms completely resolved. Procedural complications were limited to one local wound hematoma. No graft thromboses occurred during follow-up to 28 months (mean, 17 months). Endovascular iliac grafts in combination with standard femorofemoral bypass grafts may be an effective alternative to axillobifemoral bypass in high-risk patients who have diffuse aortoiliac occlusive disease, particularly when bilateral axillary-subclavian disease is present.

Analysis of cardiac shunting in the turtle Trachemys (Pseudemys) scripta: application of the three outflow vessel model.

Blood distribution within the ventricle was analysed in acutely prepared turtles Trachemys scripta by measuring the oxygen concentration and flow rates of blood in the central vessels. Pulmonary (Qp) and systemic (Qs) blood flow rates were similar when total cardiac output (Qtot) was below 40 ml min-1 kg-1. Above this value, increments of Qtot were directed to the pulmonary circuit, with Qs levelling off at approximately 20 ml min-1 kg-1. When Qtot was larger than 40 ml min-1 kg-1, the systemic circuit was almost exclusively perfused by left atrial blood and systemic venous return was almost all directed towards the lungs. Blood oxygen levels and flow rates were consistently higher in the right aorta than in the left aorta. Blood movement within the ventricle, coupled with differences in ejection timing, is probably the decisive factor determining this pattern of blood distribution in the turtle heart.

Defining the critical limit of oxygen extraction in the human small intestine.

Although animal models have been used to characterize the relation between oxygen consumption and blood flow, reliable data have not been generated in the human small intestine. We perfused segments of human small intestine by using an ex vivo perfusion circuit that allowed precise manipulation of blood flow and perfusion pressure. Our goal was to define the critical level of intestinal blood flow necessary to maintain the metabolic needs of the tissue. Human small intestine (n = 5) tissue obtained at transplantation harvest was transported on ice to the laboratory. A 40-cm mid-jejunal segment was selected for perfusion, and appropriate inflow and outflow vessels were identified and cannulated. Perfusion with an autologous blood solution was initiated through an extracorporeal membrane oxygenation circuit. After a 30-minute equilibration period, arterial and venous blood gases were measured at varying flow rates while maintaining a constant hematocrit level. Arterial and venous oxygen content, arteriovenous oxygen difference (A-VO2 diff), and oxygen consumption (VO2) were then calculated. Our results demonstrated that at blood flows > 30 ml/min/100 g, VO2 is independent of blood flow (1.6 +/- 0.06 ml/min/100 g), and oxygen extraction is inversely related to flow. Below this blood flow rate of 30 ml/min/100 g, oxygen extraction does not increase further (6.3 +/- 0.3 vol%), and VO2 becomes flow dependent. This ex vivo preparation defines for the first time a threshold value of blood flow for small intestine below which oxygen consumption decreases (30 ml/min/100 g). Previous animal studies have correlated such a decrease in oxygen consumption with functional and histologic evidence of tissue injury. This "critical" flow rate in human intestine is similar to that found previously in canine and feline intestine, but lower than that of rodent species.

Intraarterial pressure measurements during angiographic evaluation of peripheral vascular disease: techniques, interpretation, applications, and limitations.

Many operative and percutaneous procedures are available for the treatment of occlusive disease involving the lower-extremity arterial system. Peripheral vascular disease involving the aorta and lower-extremity vessels usually is attributable to atherosclerosis. The lower-extremity arterial supply is divided segmentally into the inflow (aortoiliac) and outflow (femoropopliteal and tibioperoneal) vessels. Given the length of the lower-extremity vascular system, the propensity for multifocal disease, and the possibility of a nonvascular cause for a patient's symptoms, both localization of disease in arterial segments and determination of the hemodynamic impact of diseased sites are important for judicious treatment planning. This review focuses on the use of intraarterial pressure measurement as an adjunct to angiography and intravascular intervention in evaluating the significance of arterial occlusive disease in lower-extremity arteries.

Polytetrafluoroethylene bypasses to infrapopliteal arteries without cuffs or patches: A better option than amputation in patients without autologous vein

This study was undertaken to evaluate our results of polytetrafluoroethylene (PTFE) tibial and peroneal artery bypasses done for limb salvage. Within a group of patients undergoing infrainguinal limb salvage bypasses at our institution between January 1986 and May 1995, 63 patients faced an immediate amputation, had no autologous vein on duplex examination and operative exploration, and had only a tibial or peroneal artery as an outflow vessel for bypass. Most of these patients (82%) had two or more prior ipsilateral infrainguinal bypasses. These 63 patients underwent 66 PTFE bypasses to a tibial or peroneal artery without a distal anastomotic vein cuff or an adjunctive arteriovenous fistula. Our results were then compared with those reported from infrapopliteal (crural) bypasses performed with alternate autologous vein sources or PTFE in conjunction with various recommended adjuncts. The 3- and 5-year cumulative primary graft patency rates for our PTFE infrapopliteal bypasses were 39%+/-7% and 28%+/-9%, respectively. Secondary graft patency rates were 55%+/-8% and 43%+/-10% at 3 and 5 years, respectively. Limb salvage rates were 71%+/-7% at 3 years and 66%+/-8% at 5 years. Two-year actuarial patient survival rate was only 67%+/-7%. These results indicate that a PTFE bypass to an infrapopliteal artery remains a worthwhile option in patients without usable autologous vein. The secondary patency and limb salvage rates were acceptable in this setting and were not significantly different from the best results reported with prosthetic tibial/peroneal bypasses with distal vein cuffs or patches (74% at 1 year; 58% at 3 years), arteriovenous fistulas (71% at 1 year) or composite arm vein grafts (39% and 29% at 3 and 5 years, respectively).

Clinical and Angiographic Selection Factors for Thrombolysis as Initial Therapy for Acute Lower Limb Ischemia

The purpose of this study was to determine whether angiographic patterns correlate with the clinical severity of acute lower limb ischemia (ALLI) and with the outcome of treatment with percutaneous intraarterial thrombolysis (PIAT). A retrospective analysis was conducted of angiograms and case records of 186 consecutive PIAT infusions in 160 patients with ALLI. The number of segments of occlusions; associated stenoses of inflow, outflow, and collateral vessels; and the demonstration of patent distal vessels were correlated with severity of ischemia and outcome of PIAT. Occlusions requiring flow to traverse one collateral bed to supply patent distal vessels (angiographic category I) correlated with the "viable" clinical classification of ALLI. Those requiring blood to flow through two contiguous collateral beds to supply patent distal vessels (category II) correlated with the "threatened" clinical classification. Occlusions with distal propagation that occluded the distal vascular bed (category III) correlated with the "irreversible" clinical category. Rates at 30 days for patency, amputation, and mortality were as follows for category I: 100%, 0%, and 0%; category II: 90%, 8.6%, and 0.7%; and category III: 55%, 19%, and 5%, respectively. Angiographic patterns correlate well with clinical severity of ischemia and predict the outcome from PIAT as initial therapy of ALLI. Amputation and mortality rates are less than those reported for emergency surgical treatment of ALLI.