Prevalence of true vein graft aneurysms: implications for aneurysm pathogenesis

External bleeding from femoro-crural vein bypass with aneurysmal dilation

Deaths due to external bleeding outside the hospital setting are often suspected to involve violence. However, some disease-related causes, can also lead to fatal external bleeding. While bleeding from natural body orifices is a common end stage of non-curable gastrointestinal bleeding, fatal bleeding via newly formed skin defects is quite rare and highly suspicious in light of external impact. Reliable clarification of the source and cause of bleeding is only possible in the context of an autopsy. The reported case involves the death of a man early 60 s who bled to death as a result of rupture of a femoro-crural bypass. The rupture originated from a rare true aneurysm of an autologous femoro-crural vein bypass implanted 8 years before due to peripheral arterial occlusive disease (PAD) with gangrene. The aneurysm rupture passed all subcutaneous and skin layers leading to fatal external bleeding.

Rupture of an Aneurysmal Arteriovenous Fistula in an In Situ Vein Bypass

We report a case of rupture of an aneurysm on a residual arteriovenous fistula, five years after a femoral to posterior tibial artery bypass for critical ischemia of the right lower limb. This is a 48-year-old patient admitted to the emergency room for hemorrhagic shock following a rupture of a varicose bundle at the level of the posterior surface of the right thigh. The CT angiography confirmed the presence of multiple residual arteriovenous fistulas, which became aneurysmal. The exclusion of the latter by ligature-section made it possible to stop the hemorrhage while preserving the bypass.

The VA vascular injury study: A glimpse at quality of care in Veterans with traumatic vascular injury repair

OBJECTIVE

The high number of limb injuries among Post-9/11 Veterans and their long-term care pose significant challenges to clinicians. Current follow-up for extremity arterial vascular injury (EVI) is based on guideline-concordant care for treatment of peripheral vascular disease (GCC-PVD), including anticoagulant/antiplatelet or statin therapy and duplex ultrasound. No best practices exist for arterial EVI. Our goal was to determine correlates of GCC-PVD and other care among Post-9/11 Veterans with combat-related arterial EVI.

MATERIALS AND METHODS

We identified Post-9/11 Veterans with arterial EVI who underwent initial limb salvage repair or ligation (e.g., for single-vessel injury) attempt per DoD Trauma Registry validated by chart abstraction. Veterans Health Administration (VHA) data characterized the cohort in the first five years of VHA care. Models predicted (a) GCC-PVD, (b) pain clinic use, (c) mental/behavioral health care, (d) long-term opioid use, and (e) time to complication, controlling for injury severity and type, mental health parameters, and demographics.

RESULTS

The 490-Veteran cohort with validated arterial injury was 77% White averaging 25.2 years at injury (range: 18-56). Mechanism of injury was primarily explosive (63%). Veterans had Injury Severity Scores classified as mild (60%), moderate (25%) and severe (15%). Approximately 25% received at least one component of VHA GCC-PVD including 8% arterial ultrasounds, 5% statins, and 11% anticoagulants/antiplatelets; 77% had mental/behavioral healthcare. GCC-PVD, as well as PTSD and substance use disorders, were associated with receipt of mental/behavioral health care. Complications affected 46% of the cohort and were more common among those prescribed 90+ days of opioids or receiving GCC-PVD.

CONCLUSION

Despite injury severity (40% moderate/severe), only 25% of cohort patients received VHA GCC-PVD, and nearly half had complications from their arterial injury. Receiving GCC-PVD appeared to potentiate receiving care for mental and behavioral disorders.

IMPACT

The treatment gap in Veterans with arterial EVI may be due to lack of appropriate guidelines, lack of vascular specialists in VHA or accessing care outside the VHA. Focused study of care options and their outcomes will help define optimal care processes for combat Veterans with arterial EVI.

Femoropopliteal Bypasses with Varicose Great Saphenous Vein

The great saphenous vein is the conduit of choice for femoropopliteal or infrapopliteal bypass, but it is traditionally recommended that varicose vein grafts (VVGs) should not be used for bypass conduits owing to the risk of immediate rupture or long-term aneurysmal change. Herein, we report two cases of femoropopliteal bypass with VVGs. They achieved primary patency without aneurysmal formation after 32 and 17 months. Therefore, VVGs without morphologically conspicuous abnormalities are worth considering for usage as a vein graft.

External stenting and disease progression in vein grafts 1 year after open surgical repair of popliteal artery aneurysm

OBJECTIVE

Open surgical repair remains the gold standard treatment for popliteal artery aneurysms (PAA). The objective of this study was to evaluate the safety of external stenting and its medium-term effect on vein graft disease after open PAA repair.

METHODS

Between December 2017 and September 2019, 12 consecutive patients with PAA underwent open surgical repair with externally stented saphenous vein grafts. Duplex ultrasound scanning of the grafts was performed at discharge and at 3, 6, and 12 months after the procedure to evaluate graft patency, average lumen diameter and lumen uniformity.

RESULTS

Eleven patients underwent aneurysm ligation and bypass grafting and one patient was treated with aneurysm exclusion and interposition of a venous segment. External stenting of the vein graft was successful in all patients. The mean follow-up time was 12 months (range, 7-17 months), with a primary patency rate of 100% and no graft revisions or reinterventions. The mean lumen diameters at 3, 6, and 12 months were 5.9 ± 1.2 mm, 5.7 ± 0.8 mm, and 5.7 ± 0.7 mm, respectively, with no significant changes between 3 and 6 (P = .34) and between 6 and 12 months (P = .34). The coefficient of variance at 3, 6, and 12 months was 8.2 ± 9.3, 9.4 ± 7.2, and 10.4 ± 8.9, respectively, with no significant change between 3 and 6 months (P = .78) or 6 and 12 months (P = .98). No mortality or amputations were recorded throughout the follow-up period.

CONCLUSIONS

External stenting of vein grafts in open surgical repair of PAA is feasible and safe. This technique may potentially improve the outcomes of surgical repair in patients with PAA.

Systematic Review of the Co-Prevalence of Arterial Aneurysms Within the Vasculature

OBJECTIVE

Aneurysms are considered focal manifestations of a systemic vascular condition, and various studies report co-prevalence of aneurysms in different vascular beds. Insight into profiles of patients at risk of multiple aneurysms is lacking, and few clinical algorithms exist if additional screening is indicated. This systematic review assessed the co-prevalence of aneurysms in different vascular beds and analysed putative risk factors for multiple aneurysms.

METHODS

Medline, Embase, and Cochrane libraries were searched up to February 2020 for studies reporting co-prevalence of aneurysms in different vascular beds using the keywords: "aneurysm", "co-prevalence", or synonyms. All studies were reviewed by two authors independently. Studies were excluded if they described concomitant treatment of multi-aneurysms, or if the aneurysm was reported solely bilateral, post-dissection, mycotic, traumatic, iatrogenic, or caused by a connective tissue disease. Radar plots were used to indicate studies that found an association between the investigated features and aneurysm co-prevalence against those that did not.

RESULTS

Thirty-two studies met the inclusion criteria, describing in total 16 353 patients of whom 2 015 had at least one additional aneurysm. The weighted co-prevalence was 16.9% (95% confidence interval [CI] 11.8-22.6), I² > 90%. At least 19 combinations of aneurysms were described, mostly derived from retrospective studies. Seventeen of 32 (53%) studies described concurrent aneurysms in patients with an abdominal aortic aneurysm. Predominantly positive associations were found for higher age, hypertension, stenotic disease, presence of multiple (at least three) aneurysms, and primary aneurysm size.

CONCLUSION

Approximately one in six patients with a primary aneurysm harbours an additional aneurysm, increasing to one in four if the patient has a popliteal artery aneurysm. Higher age, hypertension, stenotic disease, presence of multiple (at least three) aneurysms, and primary aneurysm size were predictive of aneurysm co-prevalence. These clinical predictors may assist when deciding whether a patient with a primary aneurysm needs to be screened for additional aneurysms.

Pseudoaneurysm Development after Drug-Eluting Balloon (DEB) Angioplasty of a Venous Femoropopliteal Bypass Graft

Endovascular recanalization of occluded venous femoropopliteal bypass grafts is widely used because of easy access. This case report describes pseudoaneurysm developing 4 weeks after endovascular recanalization of an occluded in situ venous femoropopliteal graft. The patient was treated for a popliteal aneurysm with a venous femoropopliteal bypass graft, which subsequently occluded. Four weeks after DEB PTA, the occluded graft developed 3 pseudoaneurysms. Impaired vessel wall healing after intraluminal paclitaxel administration could have contributed to this. This case adds a perspective to the choice of treatment of occluded venous femoropopliteal bypass grafts.

Late Development of a Large Arteriovenous Fistula with Aneurysm in an In Situ Vein Bypass Graft

We report a case of saphenous vein bypass aneurysm and arteriovenous fistula in a 65-year-old man, 20 years after an in situ vein bypass for occlusive disease. He was found to have patent venous branches which kept the bypass open despite distal anastomotic occlusion. The saphenous vein was successfully excised without distal revascularization due to sufficient native arterial flow. This is the first reported case of aneurysmal degeneration of an in situ vein conduit with occluded distal anastomosis and patent venous side branches. Ultrasound surveillance is warranted for all bypass procedures, and early endovascular or open revisions can prevent late complications.

Saphenous vein graft aneurysm formation in a patient with idiopathic multiple aneurysms

True aneurysmal vein graft dilation is rare, and its etiology remains speculative. However, systemic dilation diathesis is regarded as a risk factor. We herein report a case of a rapidly expanding aneurysm in a great saphenous vein graft, resulting in distal malperfusion in a patient who had previously undergone open repair of multiple popliteal artery aneurysms. After an unsuccessful endovascular intervention, the dilated section was eventually replaced by a reversed segment of the contralateral great saphenous vein. Subsequent whole-exome sequencing identified no relevant mutations. This case provides further evidence that aneurysmal disease may be associated with systemic dilation diathesis.

Aneurysmal degeneration of vein conduit used for vascular reconstruction-Case report and literature review

INTRODUCTION

Popliteal artery aneurysms (PAA) are the most prevalent form of peripheral arterial aneurysms. Greater saphenous vein grafts and endoaneurysmorrhaphy remains the mainstay therapy for open repair of PAA. True aneurysmal degeneration of lower extremity infrainguinal autologous vein grafts are relatively rare and its etiology is not completely understood.

CASE PRESENTATION

We present a case of a 57-year-old man with recurrent autologous venous graft aneurysmal dilatations following a surgical popliteal artery aneurysm repair.

DISCUSSION

The pathogenesis of true aneurysmal graft dilatation remains speculative with possible pathogenesis including progression of underlying atherosclerosis, systemic dilating diathesis, autologous venous graft varicosities, low-grade infections and post-stenotic dilatations. Management of venous graft aneurysms should be subjected to the same criteria as other aneurysms. Diagnosis requires a high index of suspicion. The initial study of choice is duplex ultrasonography as it can diagnose the aneurysm and distinguish it from other popliteal masses, provide accurately measurements and identify thrombus within the aneurysm. Once diagnosed, surgical repair should be performed as soon as possible as graft dilatation tends to occur overtime and is typically followed by a rapid increase in size over a short period of time.

CONCLUSION

Aneurysmal degeneration of autologous saphenous venous graft following PAA repairs occur infrequently. Its etiology remains largely speculative. Accurate diagnosis and early surgical intervention can prevent progression of aneurysmal dilatation and minimize the potential of complications.

Giant vein graft aneurysm complicated by Loeys-Dietz syndrome

Loeys-Dietz syndrome (LDS) is a recently reported autosomal dominant aortic aneurysm syndrome with widespread systemic involvement. Although connective tissue diseases carry a theoretical risk of aneurysmal degeneration in vein grafts, there are no reports of vein graft aneurysm (VGA) in patients with connective tissue disease. We herein report the first case of a giant VGA that was manifested 5 years after the reconstruction of a popliteal artery aneurysm associated with LDS. A pathologic examination of the VGA revealed high proteoglycan deposition and medial degeneration of the diffuse type in the VGA; these findings conformed to LDS.

Aneurysmal degeneration of deep lower extremity vein conduits used for vascular reconstruction

BACKGROUND

Successful outcomes have been reported with the use of femoropopliteal vein (FPV) grafts as arterial conduits. We identified 2 patients with a rare complication, true, nonanastomotic aneurysmal degeneration.

METHODS

Patients from 1997 through 2009 that utilized FPV grafts for revascularization were analyzed. We contacted survivors by phone and conducted a literature search of FPV aneurysms.

RESULTS

Of the total of 14 patients in our practice whose FPV was used as a conduit during the study period, 2 developed nonanastomotic FPV graft aneurysms. The mean follow-up time was 33.44 months. Literature review uncovered only 1 previously published case of FPV aneurysmal degeneration.

CONCLUSIONS

Our experience suggests that nonanastomotic aneurysms of FPV grafts may occur more often than those suspected previously. Our study represents the first reports of aneurysmal degeneration affecting FPV grafts when used for vascular reconstructions.

Bypass Grafts: The State of the Art

The treatment options for infra-renal arteriosclerotic occlusive (ASO) vascular disease have never been more varied. The history of open revascularization procedures now exceeds 60 years. This represents three generations of vascular surgeons, the most recent of whom have witnessed more than 30 years of endovascular surgery development and dissemination. Both open and endovascular treatments should be considered mature; moreover, we are improving our understanding of the strategies and tactics that lead to the clinical application of one approach instead of the other. There are other important factors in the choice of a treatment modality to be used for a specific patient. Prime among these is evolving patterns of occlusive disease and the increasing severity of arterial calcification.

Eph-B4 prevents venous adaptive remodeling in the adult arterial environment

Eph-B4 determines mammalian venous differentiation in the embryo but is thought to be a quiescent marker of adult veins. We have previously shown that surgical transposition of a vein into the arterial environment is characterized by loss of venous identity, as indicated by the loss of Eph-B4, and intimal thickening. We used a mouse model of vein graft implantation to test the hypothesis that Eph-B4 is a critical determinant of venous wall thickness during postsurgical adaptation to the arterial environment. We show that stimulation of Eph-B4 signaling, either via ligand stimulation or expression of a constitutively active Eph-B4, inhibits venous wall thickening and preserves venous identity; conversely, reduction of Eph-B4 signaling is associated with increased venous wall thickness. Stimulated Eph-B4 associates with caveolin-1 (Cav-1); loss of Cav-1 or Eph-B4 kinase function abolishes inhibition of vein graft thickening. These results show that Eph-B4 is active in adult veins and regulates venous remodeling. Eph-B4-Cav-1-mediated vessel remodeling may be a venous-specific adaptive mechanism. Controlled stimulation of embryonic signaling pathways such as Eph-B4 may be a novel strategy to manipulate venous wall remodeling in adults.

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.

Treatment of popliteal aneurysms by femoral artery transposition: long-term evaluation

A multicentric retrospective study was carried out on 29 operations (28 patients) to evaluate the long-term results of the treatment of popliteal artery aneurysms by transposition of the superficial femoral artery (SFA). This treatment consisted in proximal and distal ligation and bypass grafting or endoaneurysmorrhaphy followed by reconstruction of the popliteal artery. This surgery was always performed when the homolateral SFA could be used. After surgery, every patient was prescribed a long-term antiplatelet treatment. Mean follow-up was 39.2+/-28 months. Actuarial primary patency was 100% at 1 year and 92% at 3 years. No patients presented with either aneurysmal evolution of arterial graft or septic complication of prosthetic bypass. SFA can be used to treat isolated popliteal aneurysms with satisfying long-term results. This technique is an alternative to the use of autologous saphenous vein.

Review of Current Theories for Abdominal Aortic Aneurysm Pathogenesis

Atherosclerotic plaques are a feature of abdominal aortic aneurysms (AAAs). Atherosclerosis and AAA appear to share similar risk factors. These observations have led to the conclusion that AAAs are a consequence of advanced atherosclerosis.

This review explores current theories regarding the pathogenesis of AAA and their implications for treatment.

A systematic literature search was conducted using the search terms abdominal aortic aneurysm, atherosclerosis, pathogenesis, and systemic disease. Articles were categorized according to the association of AAAs with atherosclerosis, arteriomegaly, peripheral aneurysm, systemic expression, genetics, autoimmunity, oxidative stress, and systemic disease. Twenty-nine articles reporting changes in the systemic vasculature associated with AAA and 12 articles examining the shared risk factor hypothesis were identified.

There is insufficient evidence to confirm that AAAs are the result of advanced atherosclerosis. The bulk of evidence points to AAA disease being a systemic disease of the vasculature, with a predetermined genetic susceptibility leading to a phenotype governed by environmental factors.

Spontaneous Vein Graft Rupture after Infrainguinal Vascular Reconstruction: Report of Three Cases

We report three cases of spontaneous vein graft rupture within 2 weeks of infrainguinal vein bypass for limb salvage. Two of the three ruptures were in the distal vein graft and the last just beyond the proximal anastomosis. All were longitudinal slits in the vein with no proximity to branches or valves. Endovascular treatment failed in one patient. Surgical correction with graft salvage was possible in all three cases. This may be an ischemic injury analogous to carotid vein patch rupture, nonapparent trauma to the vein, or simply mechanical stress causing vein rupture with arterial flow.

Matrix metalloproteinase-2: the forgotten enzyme in aneurysm pathogenesis

The pathogenesis of abdominal aortic aneurysm (AAAs) involves progressive cycles of proteolysis and inflammation, the product of proteolysis driving subsequent inflammation. Little is yet known about the initiating events. We review the specific literature examining the possibility that MMP-2 may be the initial catalyst. Histologically, elastolysis is one of the earliest observable events in aneurysm genesis. Matrix metalloproteinase-2 (MMP-2), as the dominant gelatinase differentially expressed in aneurysmal tissue and cells derived from aneurysms, would be a good candidate. We report the results of in vivo and in vitro experiments, which lend support to the importance of MMP-2 as an aneurysmal initiator.

Long-Term Results of Venous Bypass for Lower Extremity Arteries with Selective Short Segment Prosthetic Reinforcement of Varicose Dilatations

The long-term benefit of venous bypass has been clearly demonstrated, but procedure feasibility is contingent upon availability of a suitable vein. In this study, we evaluated the outcome of venous bypasses performed by the first author using veins presenting dilatations that were selectively reinforced with a short prosthesis. The purpose was to answer three questions. First, should ectasis be reduced before reinforcement? Second, do hyperplasia and stenosis develop in reinforced zones? Third, do dilatation and rupture develop in unreinforced zones? Twelve patients, including 10 men and 2 women ranging in age from 36 to 77 years (median 68), underwent bypass for peripheral artery disease in seven cases, popliteal aneurysm in four, and prosthetic rupture in one. Ten patients had poor distal runoff. The bypass was femoral-to-popliteal in eight cases, femoral-to-infrapopliteal in three, and popliteal-to-popliteal in one. The graft was reversed in nine cases and ex situ devalvulated in three. The number of prosthetic reinforcements used was one in two cases, two in three cases, three in six cases, and four in one case. All but one prosthetic reinforcement were made of polytetrafluoroethylene (PTFE). Bypass occlusion was observed in two cases, including one case observed in the early postoperative period after bypass for limb salvage in a young man in whom distal runoff was limited to a few collaterals and one case that occurred 4 years after a repeat bypass procedure. The other 10 bypasses remained patent throughout follow-up, which varied from 1 to 11 years (median 4). There were three deaths during follow-up. Doppler ultrasound revealed no stenosis in the reinforced zones and no dilatation in the unreinforced zones but demonstrated progressive deterioration of the runoff in 50% of cases. At the last follow-up examination, two bypasses were patent despite poor runoff. Although the number of patients in this series was small, the outcome of venous bypass using reinforced vein grafts appeared clearly better than outcomes of prosthetic bypass reported in the literature. Reinforcement can be easily achieved using a short, thin-walled PTFE prosthesis adjusted to the proper diameter by gentle dilatation using forceps. Unlike most authors, we do not recommend reducing dilatation by resection or oversewing. Reinforced zones did not develop stenosis and unreinforced intermediate zones showed little or no dilatation and no risk of rupture.

Diameter comparison of saphenous vein bypasses for popliteal aneurysm versus peripheral arterial occlusive disease in matched subjects

Previous research has suggested that arterial aneurysm might result from a systemic tendency to dilatation. This systemic effect would involve both arterial and venous dilatation. The authors investigated whether venous grafts implanted to bypass popliteal artery aneurysms (PAA) had larger diameters than those implanted to treat peripheral arterial occlusive disease (PAOD). They compared representative diameters of 20 vein grafts implanted for PAA with matched bypass grafts implanted for PAOD. Graft diameters were obtained by means of CVI-Q M-mode ultrasound imaging. Each PAA patient/graft was matched to an equivalent PAOD patient/graft based on the patient's gender and age and the vein graft type and distal anastomosis. Secondarily, graft proximal anastomosis was matched in 60% (12/20) of the cases. Age was matched if the difference was < or = 4 years. Average age at the time of surgery was 68 +/-12 years for PAA and 68 +/-13 for PAOD groups. There were 11 reversed greater saphenous vein (GSV), 2 nonreversed GSV, and 7 in situ GSV in each group. Distal anastomoses were at the popliteal (15), peroneal (3), posterior (1), and anterior tibial (1) arteries in each group. Matching was not possible for lesser saphenous and cephalic vein grafts or bypasses to the tibial-peroneal trunk. Graft diameters were significantly larger for the PAA group, 6.24 +/-0.66 mm (standard deviation), than for the PAOD group, 5.73 +/-0.69 mm (p < 0.02, Mann-Whitney U test). Of 10 bypasses with diameter >6.5 mm, 8 were implanted for PAA. If these 10 largest bypasses were eliminated from the calculations, the mean graft diameters were 5.82 +/-0.51 mm and 5.57 +/-0.52 mm for the PAA and PAOD groups, respectively (p = 0.28). Bypass grafts implanted in PAA patients had significantly greater diameters than grafts implanted in PAOD patients. This finding, however, was due to a subgroup of grafts with diameters >6.5 mm. Perhaps systemic abnormalities associated with PAA should be first studied in patients with large vein grafts or large original veins.

Resultados tardios das reconstruções arteriais dos membros inferiores com a utilização de veias portadoras de dilatações varicosas revestidas seletivamente com segmentos protéticos

OBJETIVO: Responder as seguintes questões: 1) o revestimento protético deve ser precedido de uma redução da ectasia? 2) as zonas revestidas apresentam um risco de hiperplasia ou estenose? 3) as zonas não revestidas possuem um risco de dilatação e ruptura? MÉTODOS: Doze pacientes (10 homens e duas mulheres), com idades entre 33 e 77 anos (idade mediana = 68), foram submetidos a pontes em conseqüência de arterite (n = 7), aneurisma poplíteo (n = 4) ou ruptura de prótese (n = 1). As pontes foram fêmoro-poplíteas (n = 8), fêmoro-infra poplíteas (n = 3) e poplíteo-poplítea (n = 1). A safena utilizada foi de forma reversa em nove casos e ex situ devalvuladas em três casos. Os revestimentos foram aplicados em número de um (n = 2), dois (n = 3), três (n = 6) e quatro (n = 1). Todos, exceto um, foram de PTFE. RESULTADOS: Duas pontes ocluíram, uma precocemente por déficit de leito distal e outra 4 anos após a operação. As outras 10 pontes permaneceram pérvias durante o acompanhamento, que variou entre 1 e 11 anos (mediana = 4 anos). Metade dos casos apresentou uma deterioração progressiva do leito distal. No último controle, duas pontes permaneceram pérvias, a despeito de um leito distal desértico. CONCLUSÃO: Os resultados desta série apresentam-se notadamente superiores aos das pontes protéicas descritas na literatura. O revestimento é efetuado facilmente com uma prótese curta de PTFE de parede fina. É inútil reduzir as dilatações antes do revestimento por sutura ou ressecção - anastomose. As zonas situadas sobre a bainha de PTFE não evoluem para estenoses. As zonas intermediárias dilatam-se por vezes moderadamente e sem risco de ruptura.

True Aneurysms in a Saphenous Vein Graft Placed for Repair of a Popliteal Aneurysm: Etiologic Considerations

Although vein graft aneurysms have been described to be atherosclerotic in nature, it has been hypothesized that vein graft aneurysms may be a part of a systemic dilating process. In the case reported here, histopathologic examination of vein graft aneurysms demonstrates aneurysmal degeneration with no atherosclerotic changes and do support the hypothesis that vein graft aneurysms may be a manifestation of a systemic dilating process.

Mega-aneurysmal degeneration of a saphenous vein graft following infrainguinal bypass. A case report

True aneurysm formation in infrainguinal autologous vein grafts is rare. The authors report a case of a patient presenting with extensive aneurysmal degeneration of a femoropopliteal bypass vein graft 13 years after the original operation and 8 years after graft revision and thrombolysis for acute occlusion. Over a 2-year period, the vein graft aneurysm expanded from 2.7 to 4.5 cm maximal diameter. He underwent exclusion and partial resection of the vein graft aneurysm with placement of a new femoropopliteal bypass using reversed saphenous vein from the contralateral leg. Histopathologic examination of the aneurysm revealed intimal fibrosis, medial degeneration, and inflammation. This case and review of the literature suggests that true infrainguinal vein graft aneurysms occur infrequently and massive aneurysm degeneration is even more uncommon. Because of the rarity of true infrainguinal vein graft aneurysms, their etiology remains unclear.

Enhanced invasive properties exhibited by smooth muscle cells are associated with elevated production of MMP-2 in patients with aortic aneurysms

BACKGROUND

abdominal aortic aneurysms (AAA) are associated with excessive vascular matrix remodelling. Recent findings suggest a systemic overproduction of matrix metalloproteinases-2 (MMP-2) by vascular smooth muscle cells (SMC) may be pivotal aetiologically. SMC migration is facilitated by MMP mediated proteolysis of the basement membrane and extracellular matrix. Our aim was to see if enhanced MMP-2 production by these SMC exhibit increased invasion, in an in vitro model of migration.

METHOD

SMC were derived from inferior mesenteric vein (IMV) harvested from patients undergoing aneurysm repair (n=6) or colectomy for diverticulosis (n=6, control). Using a modified Boyden chamber chemotaxis was measured towards platelet derived growth factor (PDGF) and foetal calf serum (FCS) and invasion through a Matrigel layer. MMP-2 production was quantified by ELISA and gelatin zymography.

RESULTS

chemoattractant studies demonstrated no difference in the effect of PDGF or FCS between the two populations of SMC. However, invasive studies demonstrated a significant increase in the number of migrating SMC isolated from IMV of AAA patients. Analysis of culture media extracts revealed that this difference was associated with a significant increase in production of MMP-2.

CONCLUSION

SMC derived from patients with AAA demonstrate increased invasive properties when compared to a control group. Increased migration appears to be due to overproduction of MMP-2. The enhanced migratory potential of these SMC may lead to extracellular matrix remodelling and subsequent medial disruption demonstrated in the aneurysmal aorta. These data further support evidence of the proteolytic role of MMP-2 in cell migration.

The association between venous structural alterations and biomechanical weakness in patients with abdominal aortic aneurysms

OBJECTIVE

Abdominal aortic aneurysms (AAAs) are associated with generalized arterial dilation, torturosity, and altered matrix composition, which suggests a generalized systemic weakness throughout the entire vasculature. The aim of this study was to determine whether this phenomenon was present in the venous tissue of patients with AAA.

METHODS

A segment of inferior mesenteric vein was harvested from patients who underwent aneurysm repair (n = 11) or colectomy for diverticulosis (n = 11; control). Matrix composition of the vessel was determined with stereology, and dimensions were measured with a computerized image analysis system. Stress-strain measurements were calculated with elongation of inferior mesenteric vein tissue with a tensile-testing machine.

RESULTS

Histologic examination results showed fragmentation of elastin fibers within the medial layer of venous tissue obtained from patients with AAA. The medial elastin content in tissue from patients with aneurysms was 19.4%, compared with 26.8% in the control group (P =.018). Mechanical test results revealed a significant reduction in the tensile strength from 2.885 MPa in the control group to 1.405 MPa in the AAA group (P =.007). This reduction corresponded with a significant reduction of 59% in the stiffness of the vessel, with the mean Young's modulus of elasticity in the AAA group being 2.72 MPa, compared with 5.361 MPa in the control group (P =.0005).

CONCLUSION

Reduction in tensile strength and stiffness in venous tissue from patients with AAA was associated with disruption and reduction of the elastin content of the vein wall. These changes are analogous to those observed in the arterial aneurysmal wall and confirm the systemic nature of this disorder.

The role of matrix metalloproteinases in vascular disease

There is growing interest in the role of matrix metalloproteinases in vascular diseases. These conditions are often characterized by excessive tissue remodelling, and increased matrix metalloproteinase activity has been demonstrated in aneurysms, intimal hyperplasia and atherosclerotic plaque disruption. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology. The core of this review is derived from a MEDLINE database literature search. The review found that there is convincing evidence of increased matrix metalloproteinase activity in a spectrum of vascular disease. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in vascular disease models suggest potential therapeutic benefit. In conclusion, in vivo studies of matrix metalloproteinase inhibition are required to further study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies vascular disorders.

Impaired vasoreactivity despite an increase in plasma nitrite in patients with abdominal aortic aneurysms

OBJECTIVE

This investigation was designed to determine whether differences in vasoreactivity occur in patients with abdominal aortic aneurysms (AAAs) as compared with patients with peripheral arterial occlusive disease (PAOD) or individuals (controls) without known vascular disease.

METHODS

Brachial artery vasoreactivity was assessed in a blinded fashion, after endothelium-dependent (ED) and endothelium-independent (EI) flow-mediated vasodilation, in age-matched, male patients with AAAs (n = 11) or PAOD (n = 9) or in controls (n = 10). There were no significant differences in prestudy systolic or diastolic blood pressure, body mass index, or antilipidemic medications among the groups studied. Exclusion criteria included diabetes and tobacco use within 3 months. Quantitative ultrasound scan measurements of brachial artery diameters were performed at rest and after either forearm ischemia (ED) or administration of 0.4 mg sublingual nitroglycerin (EI). Plasma nitric oxide (NO(X) = NO(2) + NO(3)) was measured with the Saville assay. Asymmetric dimethylarginine, an endogenous inhibitor of NO(X) synthase, was measured with liquid chromatography.

RESULTS

Initial brachial artery diameters were not significantly different among the groups studied (4.85 +/- 0.18 mm for AAA group, 4.82 +/- 0.17 mm for PAOD group, 4.68 +/- 0.20 mm for controls). ED and EI vasodilation was significantly less (P =.02 and.03, respectively) in the AAA group (-1.71 +/- 1.52 and 8.33 +/- 1.13, respectively) when compared with the controls (2.96 +/- 1.04 and 13.88 +/- 2.16, respectively). However, plasma NO(X) was significantly increased (P =.01) in the AAA group (7.86 +/- 0.85 micromol/L) as compared with both controls (5.13 +/- 0.63 micromol/L) and PAOD (4.85 +/- 0.46 micromol/L). Asymmetric dimethylarginine levels were decreased in the AAA group (0.34 +/- 0.05 micromol/L) as compared with the PAOD group (0.46 +/- 0.09 micromol/L). No correlation existed between aneurysm size and ED or EI vasodilation or plasma NO(X).

CONCLUSION

This study is the first to document a divergence between ED and EI vasoreactivity and systemic NO metabolites in patients with AAAs. It is speculated that a dysfunctional vessel wall response, rather than a lack of NO, may be important in the pathogenesis of AAAs.

Ubiquitous elevation of matrix metalloproteinase-2 expression in the vasculature of patients with abdominal aneurysms

BACKGROUND

Patients with abdominal aortic aneurysms (AAAs) exhibit arterial dilation and altered matrix composition throughout the vasculature. Matrix metalloproteinase-2 (MMP-2) is the dominant elastase in small AAAs, and overexpression of MMP-2 in vascular smooth muscle cells (SMCs) may be a primary etiological event in aneurysm genesis. The aim of this study was to investigate MMP-2 production in vascular tissue remote from the abdominal aorta.

METHODS AND RESULTS

Inferior mesenteric vein (IMV) was harvested from patients undergoing aneurysm repair (n=21) or colectomy for diverticular disease (n=13, control). Matrix composition of the vessels was determined by stereological techniques. MMPs were extracted from tissue homogenates and quantified by gelatin zymography and ELISA. MMP-2, membrane type-1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinases type 2 (TIMP-2) expression were determined by Northern analysis. SMCs were isolated from IMV, and the production and expression of MMP-2 and TIMP-2 in the SMC lines were quantified. Tissue homogenates and isolated inferior mesenteric SMCs from patients with aneurysms demonstrated significantly elevated MMP-2 levels, with no difference in TIMP-2 or MT1-MMP. These differences were a result of increased MMP-2 expression. Histological examination revealed fragmentation of elastin fibers within venous tissue obtained from patients with AAA and a significant depletion of the elastin within the media. In situ zymography localized elastolysis to medial SMCs.

CONCLUSIONS

Patients with AAA have elevated MMP-2 levels in the vasculature remote from the aorta. This finding is due to increased MMP-2 expression from SMCs, a characteristic maintained in tissue culture. These data support both the systemic nature of aneurysmal disease and a primary role of MMP-2 in aneurysm formation.

Treatment of popliteal arterial aneurysm using a superficial femoral artery autograft

The usefulness of aggressive surgical management of popliteal arterial aneurysm is now widely accepted. Reconstruction is usually performed using either prosthesis or saphenous vein autograft. Autografts are preferable but not always possible because of problems of availability and congruence. An alternative conduit for cases involving lesions spanning the articular midline of the knee is the superficial femoral artery. From 1993 to 1998, we used superficial femoral artery autografts to treat a total of 18 aneurysms in 12 patients. All patients were male with a mean age of 66 years (range, 42 to 75). Fourteen aneurysms were treated during elective procedures, including four in combination with aortic repair. The remaining four were treated on an emergency basis. Exposure was achieved via the internal medial route in all cases. Treatment consisted of exclusion or aneurysmorraphy. The mean length of the autograft harvested from the ipsilateral thigh was 10.2 cm (range, 6-18). The harvested graft was replaced by a PTFE prosthesis. Our results show that superficial femoral artery autografts are a suitable alternative for two indications: for patients with small aneurysms located in the middle of the popliteal artery, since autografts provide excellent congruence, and for patients with no other useable donor vein or concurrent deep venous thrombosis.

Infrainguinal arterial reconstructions with vein grafts in patients with prior aortic procedures: the influence of aneurysm and occlusive disease

PURPOSE

This study assessed whether infrainguinal reconstructions with autogenous vein (IR) performed in patients with prior abdominal aortic aneurysm (AAA) repairs have altered graft patency, compared with those in patients who have undergone prior aortobifemoral bypass grafting procedures (ABF) for aortoiliac occlusive disease.

METHODS

From 1979 to 1998, 54 patients with prior aortic reconstructions underwent 64 autogenous single-segment saphenous IRs solely for infrainguinal occlusive disease. Included in this cohort were 30 IRs with an earlier AAA repair and 34 IRs with an earlier ABF repair. During the same period, 1274 patients underwent 1642 autogenous vein lower-extremity bypass grafting procedures (LEB). Lower-extremity native arterial (AAA, n = 6; ABF, n = 11) and vein graft diameters (AAA, n = 6; ABF, n = 6) were determined by means of angiography and duplex ultrasonography, respectively. The three reconstruction groups (AAA, ABF, LEB) were compared.

RESULTS

The patients in the three groups were similar in sex, indication for operation, proximal and distal anastomotic site, and number of distal runoff vessels. The cumulative 5-year primary graft patency rate in the AAA group (92% +/- 5%) was significantly higher (P <. 001) than that in the LEB group (63% +/- 2%) and the ABF group (44% +/- 11%). Furthermore, cumulative 5-year primary patency was decreased in the ABF group compared with the LEB group (P =.05). A significant increase in both native arterial (P =.001) and vein graft diameter (P <.05) was demonstrated by using linear regression and a Student t test, respectively, in the AAA group compared with the ABF group.

CONCLUSION

These data demonstrate that, compared with those in patients without a previous aortic procedure, IRs in patients with prior AAA repairs have significantly improved graft patency, and IRs in patients with prior ABF reconstructions for aortoiliac occlusive disease have significantly decreased graft patency. Larger arterial diameter and altered vein graft adaptation may contribute to the superior long-term outcomes of IRs in patients with prior AAA repairs.