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

PURPOSE

This study was undertaken to evaluate our results of polytetrafluoroethylene (PTFE) tibial and peroneal artery bypasses done for limb salvage.

METHODS

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.

RESULTS

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%.

CONCLUSIONS

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).

Pharmacoeconomics and formulary decision making

Pharmacoeconomic assessment of formulary actions has become increasingly common in local, national, and international formulary decision making. Tactics for managing medication use include formulary management and drug policies. Pharmacoeconomic data can provide support for these formulary decisions. For example, pharmacoeconomic data can support the inclusion or exclusion of a drug on or from the formulary and support practice guidelines that promote the most cost-effective or appropriate utilisation of pharmaceutical products. Various strategies can be used to incorporate pharmacoeconomics into formulary decision making. These include using published pharmacoeconomic studies and economic modelling techniques, and conducting local pharmacoeconomic research. Criteria for evaluating the pharmacoeconomic literature, suggestions for employing economic models, and suggested guidelines for conducting pharmacoeconomic projects are discussed. Although most formularies are viewed as cost-containment tools, formularies should not be a list of the 'cheapest' alternatives. Today's formulary should contain agents that optimise therapeutic outcomes while controlling cost. Pharmacoeconomic assessments of formulary decisions help to ensure that the agents promoted by our formularies yield the highest outcome per dollar spent. A discussion of the process for formulary action in a US hospital, the influence of pharmacoeconomics on US formularies, and strategies for incorporating pharmacoeconomics into formulary decision making are presented in this paper.

Initial experience with transluminally placed endovascular grafts for the treatment of complex vascular lesions

OBJECTIVES

Complex arterial occlusive, traumatic, and aneurysmal lesions may be difficult or impossible to treat successfully by standard surgical techniques when severe medical or surgical comorbidities exist. The authors describe a single center's experience over a 2 1/2-year period with 96 endovascular graft procedures performed to treat 100 arterial lesions in 92 patients.

PATIENTS AND METHODS

Thirty-three patients had 36 large aortic and/or peripheral artery aneurysms, 48 had 53 multilevel limb-threatening aortoiliac and/or femoropopliteal occlusive lesions, and 11 had traumatic arterial injuries (false aneurysms and arteriovenous fistulas). Endovascular grafts were placed through remote arteriotomies under local (16[17%]), epidural (42[43%]), or general (38[40%]) anesthesia.

RESULTS

Technical and clinical successes were achieved in 91% of the patients with aneurysms, 91% with occlusive lesions, and 100% with traumatic arterial lesions. These patients and grafts have been followed from 1 to 30 months (mean, 13 months). The primary and secondary patency rates at 18 months for aortoiliac occlusions were 77% and 95%, respectively. The 18-month limb salvage rate was 98%. Immediately after aortic aneurysm exclusion, a total of 6 (33%) perigraft channels were detected; 3 of these closed within 8 weeks. Endovascular stented graft procedures were associated with a 10% major and a 14% minor complication rate. The overall 30-day mortality rate for this entire series was 6%.

CONCLUSIONS

This initial experience with endovascular graft repair of complex arterial lesions justifies further use and careful evaluation of this technique for major arterial reconstruction.

Endovascular aortoiliac grafts in combination with standard infrainguinal arterial bypasses in the management of limb-threatening ischemia: preliminary report

PURPOSE

Occlusive disease of the aortoiliac segment may lead to limb-threatening ischemia, if coexisting disease is present in the femoral, popliteal, or tibial arteries. The combined treatment of severe aortoiliac and infrainguinal disease with standard techniques may be hazardous or contraindicated in patients with multiple previous reconstructions, severe comorbid medical illnesses, or both. This report summarizes the technical feasibility and early results of aortoiliac endovascular stented grafts (ESGs) in combination with conventional surgical reconstructions for the treatment of multilevel arterial occlusive disease.

METHODS

Seventeen patients with multilevel aortoiliofemoral limb-threatening occlusive disease had an ESG inserted to treat long-segment occlusive disease followed by a conventional surgical bypass. ESGs originated from the aortoiliac junction (seven) or the common iliac artery (10) and were inserted into the common femoral (nine), superficial femoral (four), or deep femoral (four) artery. ESG lengths ranged from 16 to 30 cm (mean, 21 cm). Conventional surgical bypasses were constructed from polytetrafluoroethylene (15) or saphenous vein (two) and extended to the popliteal (12), tibial (two), or contralateral femoral (three) arteries.

RESULTS

Technical success in graft insertion was achieved in 17 (94%) of 18 attempted ESG procedures. The 1-year primary and secondary cumulative patency rates for ESGs were 94% +/- 10% and 100%, respectively, whereas the 1- and 2-year patency rates for the extravascular grafts were 92% +/- 10% and 100%, respectively. Four patients had minor postprocedure complications (23%), and no deaths occurred. One patient lost his limb at 16 months because of severe pedal sepsis.

CONCLUSIONS

Transluminally placed stented grafts in combination with conventional surgical infrainguinal bypasses are a technically feasible and potentially safe option for the treatment of limb-threatening aortoiliofemoral occlusive disease and have demonstrated encouraging early patency. Long-term follow-up will be necessary before widespread application of this technique is advocated.

Transfemoral endovascular repair of iliac artery aneurysms

PURPOSE

This report evaluates the application of transfemoral endovascular repair of iliac artery aneurysms.

PATIENTS AND METHODS

Over a 20-month period, 11 patients with serious comorbid illnesses and a total of 14 iliac artery aneurysms were treated with endovascular grafts composed of polytetrafluoroethylene conduits combined with balloon expandable iliac artery stents (Palmaz). Nine right common, 3 left common, and 2 right internal iliac artery aneurysms were treated. The patients were men between 58 and 89 years of age (mean 72). Eight patients had isolated aneurysms and 3 had multiple iliac artery aneurysms.

RESULTS

Endovascular iliac grafts were successfully placed in all 11 patients. No procedural deaths occurred. Follow-up ranged from 3 to 21 months (mean 11). No acute or late graft thromboses occurred.

CONCLUSIONS

Transluminally placed endovascular stented grafts can be used to successfully exclude iliac artery aneurysms from the circulation while maintaining lower-extremity arterial perfusion. However, longer follow-up in more patients is necessary to confirm the durability of this technique.

Human transluminally placed endovascular stented grafts: preliminary histopathologic analysis of healing grafts in aortoiliac and femoral artery occlusive disease

PURPOSE

The purpose of this study was to perform a preliminary histopathologic analysis of explanted human endovascular stented grafts from patients treated for occlusive disease.

METHODS

Over a 16-month period, 26 endovascular stented grafts were placed in 21 patients with limb-threatening ischemia caused by aortoiliac or femoral artery occlusive disease. All grafts were inserted through open arteriotomies remote from the region of primary disease. During the follow-up period, two patients died of preexisting heart disease 2 weeks and 7 months after grafting, and a portion of their endovascular grafts were the surrounding artery was explanted. Specimens from five other endovascular grafts were obtained during surgical revision for graft stenosis after 3 and 6 weeks and for outflow artery stenosis after 3, 5, and 6 months. All specimens were formalin fixed and studied with hematoxylin and eosin and trichrome staining and immunohistochemically for factor VIII-related antigen, alpha actin smooth muscle, macrophage antigen (MAC-387) and PC-10 (a mouse monoclonal antibody which specifically recognizes proliferating cell nuclear antigen in paraffin sections).

RESULTS

Three weeks after placement of the stented grafts, organizing thrombus was present on both surfaces of the expanded polytetrafluoroethylene (PTFE) grafts. At 6 weeks, evidence of a neointima with overlying endothelium was seen in the perianastomotic region, and 3 months after grafting it was seen 1 to 3 cm from the anastomosis. The specimen explanted at 5 months demonstrated factor VIII-positive cells 8 cm from the anastomosis. The histopathologic condition of the external capsule appeared to vary, depending on the presence or absence of an external wrap on the PTFE graft and on which layer in the arterial wall the graft was inserted. A foreign body reaction characterized by multinucleated giant cells was seen adjacent to wrapped grafts or around those placed in an intraadventitial plane. Grafts inserted within the media were surrounded by orderly, arranged, smooth muscle cells and few mononuclear cells. Extensive smooth muscle cell proliferation (PC-10 activity) was not seen within native artery atherosclerotic plaques peripherally displaced and external to prosthetic endovascular grafts.

CONCLUSIONS

These preliminary observations on the healing of PTFE endovascular stented grafts in human beings demonstrate limited plaque hyperplasia and the presence of endothelial cells on the luminal surface remote from the graft-artery anastomosis. It is unclear whether this is a unique manifestation of healing in prosthetic grafts inserted within the walls of arteries.

Placement of endovascular stented grafts via remote access sites: a new approach to the treatment of failed aortoiliofemoral reconstructions

Endovascular grafting is a technique that combines the use of intravascular stents and prosthetic grafts to fabricate devices with unique properties. The purpose of this study is to describe the use of endovascular graft technology in the treatment of failed or failing standard aortoiliofemoral reconstructions. Over a 15-month period five patients with limb-threatening ischemia and failed aortofemoral or iliofemoral reconstructions underwent successful placement of six endovascular grafts to revascularize seven severely ischemic lower extremities. Standard thin-walled 6 mm polytetrafluoroethylene grafts and Palmaz balloon-expandable stents were used to fashion each reconstruction. In addition to the primary endovascular grafts, three patients underwent immediate femoropopliteal bypasses to improve distal outflow and one patient had a femorofemoral bypass graft to restore circulation to the contralateral ischemic extremity. The ankle/brachial indices of all patients significantly improved after the procedure (from a mean of 0.32 to a mean of 0.75) and all grafts are patent to date (mean follow-up 10 months). There were no deaths or limb loss in this group of patients. These favorable results indicate that this minimally invasive approach, which permits a new arterial graft to be inserted through a remote access site, is a valuable method for providing unobstructed arterial inflow after aortoiliofemoral graft failure. This procedure may be particularly valuable when there are contraindications to the use of axillary arteries or the thoracic aorta as alternatives to complex reoperative abdominal aortic surgery.

Transluminally placed endovascular stented graft repair for arterial trauma

PURPOSE

Intravascular stents have become important tools for the management of vascular lesions; however, stents in combination with vascular grafts have only recently reached clinical application. This report describes an experience with stented grafts for the treatment of penetrating arterial trauma.

METHODS

Seven transluminally placed stented grafts were used to treat one arteriovenous fistula and six pseudoaneurysms. These grafts were successfully inserted percutaneously or through open arteriotomies that were remote from the site of vascular trauma. The devices were composed of balloon-expandable stainless steel stents covered with polytetrafluoroethylene grafts.

RESULTS

Patency up to 14 months was achieved (mean follow-up 6.5 months) with these stented grafts. The use of stented grafts appears to be associated with decreased blood loss, a less invasive insertion procedure, reduced requirements for anesthesia, and a limited need for an extensive dissection in the traumatized field. These advantages are particularly important in patients with central arteriovenous fistulas or false aneurysms who are critically ill from other coexisting injuries or medical comorbidities.

CONCLUSIONS

The use of stented grafts already appears justified to treat traumatic arterial lesions in critically ill patients. Although the early results with the seven cases in this report are encouraging, documentation of long-term effectiveness must be obtained before these devices can be recommended for widespread or generalized use in the treatment of major arterial injuries.

Transfemoral endovascular stented graft treatment of aorto-iliac and femoropopliteal occlusive disease for limb salvage

BACKGROUND

Endovascular stented grafts employ a new technique that blends intravascular stent and prosthetic graft technologies. These devices may be used to treat arterial aneurysms, occlusive disease, and vascular injuries. This report describes the application of stented grafts to the treatment of limb-threatening ischemia secondary to occlusive disease of the aorta, iliac, and femoral arteries.

METHODS

Three patients with limb-threatening ischemia and severe comorbid medical illnesses were treated with transvascular stented grafts that were composed of 6-mm thin-walled polytetrafluoroethylene grafts and Palmaz balloon expandable stents. The grafts were inserted through a cutdown in an artery remote from the site of occlusion and introduced into the vascular system within 14-Fr introducer sheaths.

RESULTS

Technical success was documented in all three patients with restoration of arterial continuity following stent graft deployment. Patency and limb salvage has been achieved to 1 year. One patient required further dilatation of the proximal stent at 6 weeks. Complications were limited to an iliofemoral deep vein thrombosis in one patient.

CONCLUSIONS

Endovascular stented grafts can be inserted to treat limb-threatening ischemia. Although these initial results are encouraging, greater experience in more patients observed for longer periods of time is necessary before this technique can be advocated for widespread use.

Is percutaneous balloon angioplasty appropriate in the treatment of graft and anastomotic lesions responsible for failing vein bypasses?

We reviewed 95 cases of vein graft and anastomotic lesions treated with percutaneous transluminal balloon angioplasty (PTA) and 30 cases treated surgically. The therapy was deemed a failure if the lesion recurred or if the graft closed. The 21-month patency rate of lesions treated surgically was 86%, which was significantly better than the 42% patency rate for all lesions treated with PTA (P < 0.01). An evaluation of the lesion and graft characteristics that could influence the patency of stenotic lesions treated with PTA included: lesion length, minimum graft diameter, lesion location, and lesion type. The 66% patency rate at 24 months for the 41 simple lesions (single, nonrecurrent, < 15 mm in length, and within grafts > or = 3 mm minimal diameter) was significantly better than the 17% patency rate for the 50 complex lesions (multiple, recurrent, > or = 15 mm in length, or within grafts < 3 mm in minimal diameter) (P < 0.01). In addition, the 21-month patency rate for the surgically treated group (86%) was not significantly better than that of the angioplasty-treated simple lesions (66%). When feasible, vein graft lesions are best treated with simple surgical interventions. PTA can be useful to maintain the patency of severely compromised grafts prior to surgical repair, to treat simple lesions difficult to reach surgically, and for patients with medical contraindications for an operation.

Use and misuse of pharmacoeconomic terms: a definitions primer

Given the current cost-conscious health care environment, pharmacists must now be able to assess the effects of an agent from safety, efficacy, and value considerations. This article describes the various methodologies that may be used in performing pharmacoeconomic analyses and highlights the use and misuse of pharmacoeconomic terminology. Case studies relating the use of these methods to the pharmacy practice setting are presented. The technical nuances of the various methods are explained to promote a better understanding of the appropriate use of these techniques and the terminology used to describe them.

Is surveillance to detect failing polytetrafluoroethylene bypasses worthwhile?: Twelve-year experience with ninety-one grafts

PURPOSE

The purpose of this study was to review the 91 failing polytetrafluoroethylene (PTFE) grafts that were treated at our institution over the past 12 years to better understand their cause and improve the diagnosis and treatment of these grafts.

METHODS

Eighty-five patients with 91 failing grafts were retrospectively reviewed. The 144 graft-threatening lesions associated with these grafts were characterized by location (inflow artery, outflow artery, anastomosis, or graft body) and treatment method used (surgery, balloon angioplasty, or thrombolysis).

RESULTS

Progression of atherosclerotic disease was the predominant cause of failing PTFE grafts with 43 inflow lesions and 83 outflow lesions, accounting for 87% of all lesions identified. Ten lesions (7%) were noted within the prosthetic grafts, whereas only eight (6%) lesions were noted at the anastomoses. Forty stenotic lesions 2 cm in length or less were treated with percutaneous transluminal balloon angioplasty, whereas 100 lesions were treated by patch angioplasty or graft extensions. The remaining four lesions, present within the prosthetic grafts, were treated with thrombolytic therapy. The 5-year cumulative patency rate for all failing PTFE grafts was 71%, whereas that of failing femoropopliteal PTFE grafts was 64%. The 5-year limb salvage rate for all failing PTFE grafts was 73%.

CONCLUSIONS

The progression of inflow and outflow disease is the predominant cause of failing PTFE grafts, which suggests that this process is a more important cause of PTFE graft thrombosis than is generally recognized. Frequent PTFE graft surveillance may permit detection of some threatening lesions before graft thrombosis occurs and may help maintain and prolong graft patency. The enhanced 5-year patency and limb salvage rates for treated failing PTFE grafts compared with the known poor outcome after reinterventions for PTFE graft failure support the conclusion that surveillance of PTFE grafts is worthwhile.

Analysis of balloon dilatation of human vein graft stenoses

Controversy continues as to whether percutaneous transluminal angioplasty (PTA) or surgical revision is the ideal modality for the treatment of failing grafts. This prompted a histopathologic analysis of failing human vein graft segments subjected to ex vivo balloon dilatation to define variables responsible for the discrepant results. Fifteen vein graft lesions from 14 patients with failing infrainguinal bypasses were recovered after surgical excision. Each graft lesion was focal and uniform in length (2.1 +/- 0.3 cm). Rings sectioned from adjacent regions of each vein graft lesion before and after balloon inflation were processed for histologic study, photomicrography, and image analysis. Angioplasty balloon size was selected on the basis of preoperative arteriograms. Graft lesions were divided into three groups based on lesion thickness and the degree of fibrosis and cellularity seen on sections stained with Masson's trichrome. The luminal area before angioplasty was not significantly different for the three groups (p > 0.2). Vein grafts with thick intimas (group 1) had significantly less luminal dilatation after angioplasty as compared with less thick intimal lesions (groups 2 and 3; p < 0.001). Those lesions with varying degrees of cellularity (groups 2 and 3) showed no significant differences in luminal diameter after angioplasty. However, the cellular lesions in group 2 consistently formed multiple intimal flaps that could produce PTA failures even with good luminal restoration. The varying histology of vein graft lesions and associated differences in intimal thickness and cellularity may be responsible for the inconsistent results following PTA. Estimates of wall thickness before angioplasty, particularly in the intimal area, may be helpful in evaluating which lesions might benefit most from PTA.

Limb salvage surgery in end stage renal disease: is it worthwhile?

The role of limb salvage surgery in patients with end stage renal disease (ESRD) is controversial. In view of this debate, we reviewed our experience with 54 primary and 15 secondary revascularizations for limb salvage in patients with ESRD over the past decade. Thirty-seven patients required dialysis and 10 had functioning renal transplants. Severe limb threatening ischemia was the indication for all revascularizations. The 2-year cumulative secondary graft patency rate was 56.2% with an associated limb salvage rate of 71.4%. There was no significant difference in graft patency or limb salvage rates between patients requiring dialysis and those with functioning renal allografts (p = 0.5). The 30-day operative mortality for the 99 surgical procedures (69 arterial bypasses and 30 additional operations) was 13% and the 2-year patient survival was 45.6%. Six of the 15 amputations were performed despite a patent graft on limbs which had extensive infection and gangrene. We conclude that limb salvage surgery should only be undertaken with recognition of these risks in patients with ESRD or functioning renal transplants. Surgery should be performed before gangrene and infection become extensive. Patients with unrelenting infection or mid-forefoot gangrene should be considered for primary amputation.

A ten-year experience with one hundred fifty failing or threatened vein and polytetrafluoroethylene arterial bypass grafts

Between Jan. 1, 1980, and Dec. 31, 1989, 2187 infrainguinal revascularization procedures were performed. In 130 of these cases with patent bypasses, hemodynamic deterioration was suspected, and urgent arteriography was performed. Twenty additional patients with aortofemoral, femorofemoral, or axillofemoral bypasses demonstrated hemodynamic deterioration. In 93% of failing grafts the condition was suspected because of recurrent symptoms or changes in the pulse examination. Two hundred eighty-five high-grade stenotic or occlusive lesions were identified in inflow arteries, outflow arteries, within the graft, or at proximal or distal anastomoses associated with these 150 grafts. One hundred sixty-one (57%) of these lesions were in patients with failing vein grafts; 115 (40%) were in patients with failing polytetrafluoroethylene (PTFE) grafts; and 9 (3%) were associated with failing composite vein/PTFE grafts. Stenotic lesions less than 5 cm in length were initially treated with percutaneous transluminal balloon angioplasty (PTA). Occlusive lesions, stenoses greater than 5 cm in length, and PTA failures were treated surgically. The overall 6-year cumulative secondary patency rate for failing grafts was 65%, and the limb salvage rate was 75%. The extended patency rate after the first intervention in the failing state was 56% at 5 years. The 5-year secondary patency rate for grafts initially treated with PTA (58%) was not significantly different (p = 0.25) from that for grafts treated initially with surgery (71%). Percutaneous transluminal angioplasty was effective for inflow stenoses of the iliac, femoral, and popliteal arteries and for some outflow lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Interpretation of "cost-effective" and soundness of economic evaluations in the pharmacy literature

The varied interpretations of the term "cost-effective" in the pharmacy literature are discussed and the soundness of pharmacoeconomic analyses is assessed. Sixty-five studies concerning cost issues, which were published by six pharmacy journals from January 1985 to December 1990, were evaluated according to 10 methodological criteria. Two investigators independently reviewed each study and completed a data collection form; differences were discussed and resolved to ensure consistency of evaluation. In 36 (55%) of 65 articles, cost-effectiveness was misinterpreted as cost saving. Only 3 of the 10 criteria were fulfilled by 50% or more of the studies evaluated. Problem areas included the following: (1) identification of relevant costs and consequences of each strategy, (2) discounting--adjusting data to reflect the differential timing of costs and consequences, (3) incremental analysis--examining extra costs of a program relative to additional effects provided, and (4) sensitivity analysis. Many pharmacoeconomic studies inappropriately used the term "cost-effective" and inadequately addressed basic methodological components of an economic evaluation.

Interruption of critical aortoiliac collateral circulation during nonvascular operations: a cause of acute limb-threatening ischemia

In patients with aortoiliac occlusive disease interruption of critical collaterals during another nonvascular or cardiac operation may threaten limb viability. This occurred in four patients whose limb-threatening ischemia was precipitated by radical cystectomy with bilateral hypogastric artery ligation, left colon resection, or coronary artery revascularizations by means of the internal mammary artery. Important collateral pathways, the interruption of which may account for this phenomenon, are detailed, and approaches are outlined for prevention and management of acute ischemia in this setting.