Pathogenetic heterogeneity of in-stent lesion formation in human peripheral arterial disease

Markers of Restenosis after Percutaneous Transluminal Balloon Angioplasty in Patients with Critical Limb Ischemia

Among cardiovascular diseases, chronic obliterating lesions of the arteries of lower extremities, which are one of the important problems of modern healthcare, are distinguished. In most cases, the cause of damage to the arteries of lower extremities is atherosclerosis. The most severe form is chronic ischemia, characterized by pain at rest and ischemic ulcers, ultimately increasing the risk of limb loss and cardiovascular mortality. Therefore, patients with critical limb ischemia need limb revascularization. Percutaneous transluminal balloon angioplasty is one of the least invasive and safe approaches, with advantages for patients with comorbidities. However, after this procedure, restenosis is still possible. Early detection of changes in the composition of some molecules as markers of restenosis will help screen patients at the risk of restenosis, as well as find ways to apply efforts for further directions of inhibition of this process. The purpose of this review is to provide the most important and up-to-date information on the mechanisms of restenosis development, as well as possible predictors of their occurrence. The information collected in this publication may be useful in predicting outcomes after surgical treatment and will also find new ways for the target implication to the mechanisms of development of restenosis and atherosclerosis.

Systematic review and meta-analysis of drug-coated balloon for in-stent restenosis in femoropopliteal artery disease

PURPOSE

To evaluate the role of drug-coated balloon (DCB) angioplasty for in-stent restenosis (ISR) in femoropopliteal artery disease.

MATERIAL AND METHODS

Cochrane Library, Embase, and PubMed were searched without language restriction from inception to May 10, 2020.The endpoints included target lesion revascularization (TLR), recurrent ISR, clinical improvement, ankle-brachial index (ABI), and death.

RESULTS

There were five randomized controlled trials with 425 patients (218 with DCB angioplasty and 207 with plain old balloon angioplasty [POBA]) included in the meta-analysis. Compared with POBA, DCB angioplasty was associated with lower risk of TLR (odds ratio [OR] 0.21, 95% confidence interval [CI]: 0.09 to 0.49, P<0.001 at 6 months and OR 0.15, 95% CI: 0.08 to 0.30, P<0.001 at 12 months) and recurrent ISR (OR 0.22, 95% CI: 0.13 to 0.38, P<0.001 at 6 months and OR 0.31, 95% CI: 0.16 to 0.61, P<0.001 at 12 months), and superior clinical improvement (OR 1.98, 95% CI: 1.07 to 3.65, P=0.03 at 6months and OR 2.84, 95% CI: 1.50 to 5.35, P=0.001 at 12 months). There were no significant differences between groups in ABI and death. Subgroup analysis for patients with DCB angioplasty showed similar rates of TLR, recurrent ISR, clinical improvement, and death between the short lesion (<15 cm) and long lesion group (≥15 cm) (P>0.05).

CONCLUSIONS

The current meta-analysis suggests hat DCB angioplasty is an improvement over POBA for femoropopliteal ISR. Future studies about the effect of lesion length on DCB performance are still needed.

Covered Stents vs. Angioplasty for Common Iliac Artery In Stent Restenosis: A Retrospective Comparison

OBJECTIVE

The optimal endovascular treatment for common iliac artery in stent re-stenosis has yet to be assessed. Treatment options include, among others, angioplasty alone and repeated stenting with covered stents.

METHODS

This study retrospectively compared patency and target lesion revascularisation of these treatments. All patients who underwent endovascular treatment of common iliac artery in stent re-stenosis between 2007 and 2017 were included retrospectively. The primary end point was freedom from re-stenosis. Secondary endpoints were target lesion revascularisation rate (TLR) and freedom from occlusion during follow up.

RESULTS

Seventy-four interventions were included, consisting of 37 angioplasties and 37 covered stent placements in 57 patients. Freedom from re-stenosis at four years was 72.6% (95% confidence interval [CI] 51.8% - 88.7%) in the covered stent group vs. 43.5% (95% CI 25.9% - 59.8%) in the percutaneous transluminal angioplasty (PTA) group (p = .003). The target lesion revascularisation (TLR) rate was 16.4% (95% CI 7.1% - 35.6%) and 43.6% (95% CI 28.0% - 63.2%) respectively (p = .020). There was no difference in freedom from occlusion; this was 90.8% (95% CI 73.9% - 97.0%) in the covered stent group and 79.1% (95% CI 58.4% - 90.3%) in the PTA group (p = .49). The difference in freedom from re-stenosis and TLR remained significant after sensitivity and multivariable analyses.

CONCLUSION

Covered stents offer better outcomes for common iliac artery in stent re-stenosis than angioplasty alone.

Excimer laser atherectomy combined with drug-coated balloon versus drug-eluting balloon angioplasty for the treatment of infrapopliteal arterial revascularization in ischemic diabetic foot: 24-month outcomes

There are few studies on excimer laser (308 nm) atherectomy in the treatment of infrapopliteal artery disease. The purpose of this retrospective clinical study was to assess the efficacy and safety of excimer laser atherectomy (ELA) in combination with adjuvant drug-coated balloon angioplasty (DCB) compared to DCB for infrapopliteal arterial revascularization in patients with ischemic diabetic foot. From September 2018 to February 2019, a total of 79 patients with diabetic foot were treated for infrapopliteal arterial revascularization at Tianjin First Central Hospital (Tianjin, China). In this project, 35 patients were treated with ELA combined with DCB angioplasty, and 44 patients were treated with DCB angioplasty. The patients' baseline characteristics were similar between the 2 groups. The primary efficacy endpoints through 24 months were clinically driven target lesion revascularization (CD-TLR), wound healing rate, major amputation rate, and target vessel patency rate. The primary safety endpoint through 24 months was all-cause mortality. The primary efficacy results at 24 months of ELA + DCB versus DCB were CD-TLR of 14.3% versus 34.1% (p = 0.044), wound healing rate of 88.6% versus 65.9% (p = 0.019), target vessel patency rate of 80.0% versus 52.3% (p = 0.010), and major amputations rate of 5.7% versus 22.7% (p = 0.036). The safety signal at 24 months of all-cause mortality rate was 2.9% for ELA + DCB group and 4.5% for DCB group (p = 0.957). ELA combined with DCB angioplasty is more effective than DCB in the treatment of infrapopliteal artery disease in patients with ischemic diabetic foot, which can improve the wound healing rate and target vessel patency rate. There was no statistical difference in the safety results between the two groups.

Tryptophan metabolite 5-methoxytryptophan ameliorates arterial denudation-induced intimal hyperplasia via opposing effects on vascular endothelial and smooth muscle cells

Cardiovascular diseases remain the leading cause of morbidity and mortality worldwide, particularly among older adults. Despite the advent of medical technology, restenosis is still an issue after interventional procedures. Tryptophan metabolite 5-methoxytryptophan (5-MTP) has recently been shown to protect against systemic inflammatory responses. This study aimed to investigate the function and mechanisms of 5-MTP in interventional procedure-induced restenosis. We found that after mouse femoral artery denudation with a guide wire, 5-MTP accelerated recovery of endothelium in the denuded area and reduced vascular leakage and intimal thickening. 5-MTP increased endothelial cell proliferation in the denuded arteries and rescued TNF-α-reduced endothelial cell proliferation and migration, likely via maintaining vascular endothelial growth factor receptor 2 activation. In contrast, 5-MTP preserved differentiated phenotype of medial vascular smooth muscle cells (VSMCs) and decreased VSMC proliferation and migration. Furthermore, 5-MTP maintained expression levels of critical transcription factors for VSMC marker gene expressions via attenuated activation of p38 MAPK and NFκB-p65. Our findings uncover a novel protective mechanism of 5-MTP in restenosis. In response to denudation injury, 5-MTP attenuates intimal hyperplasia via concerted but opposing actions on endothelial cells and VSMCs. Taken together, our results suggest that 5-MTP is a valuable therapeutic target for arterial injury-induced restenosis.

Laser Atherectomy Combined With Drug-Coated Balloon Angioplasty Is Associated With Improved 1-Year Outcomes for Treatment of Femoropopliteal In-Stent Restenosis

Purpose: To examine whether laser atherectomy combined with drug-coated balloons (laser + DCB) can improve the outcomes of femoropopliteal (FP) in-stent restenosis (ISR). Methods: A dual-center retrospective study was conducted of 112 consecutive patients (mean age 70.3±10.6 years; 86 men) with Tosaka class II (n=29; diffuse stenosis) or III (n=83; occlusion) FP-ISR lesions. Sixty-two patients (mean age 68.5±10 years; 51 men) underwent laser + DCB while the other 50 patients (mean age 72.5±10.8 years; 35 men) had laser atherectomy plus balloon angioplasty (laser + BA). Critical limb ischemia was the indication in 33% of the interventions. The average lesion length was 247 mm. A Cox regression hazard model was developed to examine the association between laser + DCB vs laser + BA; the results are presented as the hazard ratio (HR) and 95% confidence interval (CI). One-year target lesion revascularization (TLR) and reocclusion were estimated using the Kaplan-Meier method. Results: Overall procedure success was 98% and was similar between groups. Bailout stenting was less often required in the laser + DCB group (31.7% vs 58%, p=0.006). The combination of laser + DCB was associated with improved 12-month estimates for freedom from TLR (72.5% vs 50.5%, p=0.043) and freedom from reocclusion (86.7% vs 56.9%, p=0.003). Among patients with Tosaka III FP-ISR, combination therapy with laser + DCB was also associated with increased freedom from reocclusion (87.1% vs 57.1%, p=0. 028). On multivariable analysis, treatment with laser + DCB was associated with a significantly reduced risk of reocclusion (HR 0.08, 95% CI 0.17 to 0.38; p=0.002). Conclusion: When used for treatment of complex FP-ISR lesions, DCB angioplasty combined with laser atherectomy is associated with significantly reduced 1-year TLR and reocclusion rates.

The Relationship Between the Neutrophil-Lymphocyte Ratio and In-Stent Restenosis in Patients With Femoropopliteal Chronic Total Occlusions

We investigated the relationship between the neutrophil-lymphocyte ratio (NLR) and in-stent restenosis (ISR) in patients with femoropopliteal chronic total occlusions (CTOs). The study enrolled 180 patients who had undergone successful stenting treatment for femoropopliteal CTO. Patients with ISR were subsequently classified into 2 groups: early-ISR (within 1 year) and late-ISR (after 1 year). The clinical characteristics, angiographic data, and follow-up data were recorded. The baseline NLR was significantly higher in the early-ISR group than that in the non-ISR group [3.96(2.14) and 3.33(2.73), p = .04]. Receiver operating characteristic curve analysis suggested an optimum early ISR NLR cutoff point of 3.62, which showed a sensitivity and specificity of 73.4% and 80.4%, respectively (area under the curve: 0.707, 95% confidence interval: 0.603-0.792, P < .001). A subgroup analysis was performed based on the NLR value (<3.62 vs ≥3.62). In the NLR ≥3.62 subgroup, the incidence of early ISR was higher than that of late ISR ( P < .01). In the multivariate analysis, NLR ≥3.62 was independently and positively associated with a higher risk of early ISR. In conclusion, NLR is independently associated with early ISR after stent implantation in patients with femoropopliteal CTO.

Enhanced neointimal fibroblast, myofibroblast content and altered extracellular matrix composition: Implications in the progression of human peripheral artery restenosis

BACKGROUND AND AIMS

Neointimal cellular proliferation of fibroblasts and myofibroblasts is documented in coronary artery restenosis, however, their role in peripheral arterial disease (PAD) restenosis remains unclear. Our aim was to investigate the role of fibroblasts, myofibroblasts, and collagens in restenotic PAD.

METHODS

Nineteen PAD restenotic plaques were compared with 13 de novo plaques. Stellate cells (H&E), fibroblasts (FSP-1), myofibroblasts (α-actin/vimentin/FSP-1), cellular proliferation (Ki-67), and apoptosis (caspase-3 with poly ADP-ribose polymerase) were evaluated by immunofluorescence. Collagens were evaluated by picro-sirius red stain with polarization microscopy. Smooth muscle myosin heavy chain (SMMHC), IL-6 and TGF-β cytokines were analyzed by immunohistochemistry.

RESULTS

Restenotic plaques demonstrated increased stellate cells (2.7 ± 0.15 vs.1.3 ± 0.15) fibroblasts (2282.2 ± 85.9 vs. 906.4 ± 134.5) and myofibroblasts (18.5 ± 1.2 vs.10.6 ± 1.0) p = 0.0001 for all comparisons. In addition, fibroblast proliferation (18.4% ± 1.2 vs.10.4% ± 1.1; p = 0.04) and apoptosis (14.6% ± 1.3 vs.11.2% ± 0.6; p = 0.03) were increased in restenotic plaques. Finally, SMMHC (2.6 ± 0.12 vs.1.4 ± 0.15; p = 0.0001), type III collagen density (0.33 ± 0.06 vs. 0.17 ± 0.07; p = 0.0001), IL-6 (2.08 ± 1.7 vs.1.03 ± 2.0; p = 0.01), and TGF-β (1.80 ± 0.27 vs. 1.11 ± 0.18; p = 0.05) were increased in restenotic plaques.

CONCLUSIONS

Our study suggests proliferation and apoptosis of fibroblast and myofibroblast with associated increase in type III collagen may play a role in restenotic plaque progression. Understanding pathways involved in proliferation and apoptosis in neointimal cells, may contribute to future therapeutic interventions for the prevention of restenosis in PAD.

Relationship between HLA molecules and late restenosis after coronary stent placement

OBJECTIVE

The objective of this study is to confirm whether there is relation between the human leucocyte antigen (HLA) locus and restenosis after percutaneous coronary intervention (PCI) holds in our patient population and whether it can be useful as a prognostic factor.

METHODS

We examined the HLA phenotypes in 46 consecutive patients (39 men, 7 women, mean age of 57 ± 9 years) who had successful stent implantation in the coronary artery. Selective coronary arteriography was performed 6 months after coronary stenting to assess the presence of restenosis. The HLA phenotyping was performed for HLA-A,-B,-C antigens by Terasaki microlymphocytotoxicity technique and for HLA-DR alleles with PCR-SSP technique.

RESULTS

Restenosis(R+) was present in 12 (26.1%) patients (11 men, 1 woman, mean age of 57 ± 10 years). For HLA Class I antigens frequency of HLA-B62 and HLA-CW2 antigen was slightly higher in restenotic patients but did not reach statistical significance. For HLA-DR alleles restenotic patients had higher frequencies for HLA-DRB1(∗)01(R+ %25, R- %14.7), and HLA-DR11(R+ %41.7, R- %20.6), without reaching statistical significance and lower frequencies for DR7(R+ %0, R- %17.6) and D13(R+%8.3, R- %32.4) and HLA-DR53 (R+ %25, R- %35.3) without reaching statistical significance.

CONCLUSION

In conclusion, results show that there was no relationship between the development of restenosis and HLA-subtypes.

Suppressor of cytokine signaling-3 and intimal hyperplasia in porcine coronary arteries following coronary intervention

AIMS

The growth and differentiation of cells is regulated by cytokines by binding to cell-surface receptors and activating intracellular signal transduction cascade. Suppressor of cytokine signaling (SOCS)-3 is a negative regulator of cytokines. In this study we examined the expression of SOCS-3 in porcine coronary artery smooth muscle cells (PCASMCs) in vitro and in proliferating smooth muscle cells of neointimal lesions after coronary artery intervention in a swine model.

METHODS AND RESULTS

PCASMCs were cultured and stimulated with TNF-α and/or IGF-1 individually or in combination. Protein expression of SOCS-3 was examined using Western blot. For in vivo studies, six female Yucatan miniswine were fed with special high cholesterol diet for 8 months. At 4 months of high cholesterol diet, animals underwent coronary balloon angioplasty. At the end of 8 months animals were euthanized, coronary arteries were isolated and morphological and histological studies were performed. Western blot data revealed significantly high SOCS-3 expression in PCASMCs in the presence of either TNF-α or IGF-1 (5-6 fold) alone. However, in the presence of both TNF-α and IGF-1 the SOCS-3 expression was significantly decreased (4-5 fold). Results from morphological studies including, H&E and Masson's trichrome stain showed typical lesions with significant neointimal proliferation. Histological evaluation showed expression of smooth muscle α-actin and significantly increased proliferating cell nuclear antigen (PCNA) in neointimal lesion. Interestingly, there was significantly decreased expression of SOCS-3 in smooth muscle cells of neointima as compared to control.

CONCLUSIONS

These data suggest that SOCS-3 expression is decreased in proliferating smooth muscle cells of neointimal lesions. This leads to uncontrolled growth of vascular smooth muscle cells in injured arteries leading to restenosis. Therefore, local delivery of SOCS-3 gene at the site of injury after coronary artery intervention could regulate the proliferation of vascular smooth muscle cells and help in preventing the neointimal hyperplasia and restenosis.

Análise morfométrica da carótida de suínos submetidos a angioplastia com ou sem implante de stent de cromo-cobalto

Contexto: A hiperplasia intimal é a reação tardia mais comum decorrente da angioplastia. O uso de stents de cromo-cobalto é bem estudado na circulação coronariana, porém não há muitos estudos que abordem o uso desses stents nas circulações carotídea e periférica. Objetivo: Analisar mediante morfometria a reação intimal presente na artéria carótida de suínos submetidos a angioplastia isoladamente e a angioplastia seguida de implante de stent de cromo-cobalto. Materiais e métodos: Em oito suínos, foi realizada angioplastia da artéria carótida comum direita e angioplastia seguida de implante de um stent de cromo-cobalto na artéria carótida comum esquerda. Após 4 semanas, os animais foram submetidos a eutanásia para a retirada de amostras de tecido arterial e preparo de lâminas histológicas. As imagens das lâminas foram digitalizadas e analisadas por programa de morfometria digital. A análise estatística foi realizada através da média e desvio padrão das áreas em cada grupo, utilizando-se o Teste t de Student. O valor de p < 0,05 foi considerado significativo. Resultados: O implante do stent provocou maior grau de hiperplasia comparado à angioplastia isolada. A diferença em resposta ao implante de stent foi estatisticamente significativa quando as áreas do lúmen, da lâmina elástica interna e da lâmina elástica externa foram comparadas entre os dois grupos. Não se observou diferença significativa quando se realizou a comparação entre as camadas médias dos dois grupos. Conclusão: O implante de stent de cromo-cobalto gerou um espessamento intimal maior do que o produzido apenas pela angioplastia, porém ele não foi suficiente para reduzir o lúmen arterial.

Evaluation of peripheral artery stent with 64-slice multi-detector row CT angiography: prospective comparison with digital subtraction angiography

PURPOSE

To assess the accuracy of 64-slice multi-detector row computed tomography (MDCT) angiography in the evaluation of peripheral artery in-stent or peristent restenosis, with conventional digital subtraction angiography (DSA) as the reference standard.

MATERIALS AND METHODS

Forty-one patients (30 men, 11 women; mean age, 69.8+/-9.2 years) with symptomatic peripheral arterial occlusive disease after peripheral artery stenting (81 stented lesions) underwent both conventional DSA and 64-slice MDCT angiography. Each stent was classified as evaluable or unevaluable, and every stent was divided into three segments (proximal stent, stent body, and distal stent), resulting in 243 segments. For evaluation, stenosis was graded as follows: 1, none or slight stenosis (<25%); 2, mild stenosis (25-49%); 3, moderate stenosis (50-74%); 4, severe stenosis or total occlusion (> or =75%). Two readers evaluated all CT angiograms with regard to narrowing of in-stent or peristent restenosis by consensus. Results were compared with findings of the DSA.

RESULTS

Of 81 stents, 62 (76.5%) were determined to be assessable. The metal artifact of the gold marker and motion artifact increased uninterpretability of the images of stents. Overall, 24 of 28 in-stent restenosis and 38 of 53 persistent restenosis were correctly detected by MDCT (85.7% and 71.7% sensitivity). In evaluable stents, 21 of 22 in-stent restenoses and 27 of 28 persistent restenosis were correctly detected (95.4% and 96.4% sensitivity). Additionally, as the grade of stenosis increases, the mean level of CT values in the stent lumina decreases linearly accordingly.

CONCLUSION

64-Slice MDCT has a high accuracy for the detection of significant in-stent or peristent restenosis of assessable stents in patients with peripheral artery stent implantation and therefore can be considered as a valuable noninvasive technique for stent surveillance.

Analysis of arterial intimal hyperplasia: review and hypothesis

BACKGROUND

Despite a prodigious investment of funds, we cannot treat or prevent arteriosclerosis and restenosis, particularly its major pathology, arterial intimal hyperplasia. A cornerstone question lies behind all approaches to the disease: what causes the pathology?

HYPOTHESIS

I argue that the question itself is misplaced because it implies that intimal hyperplasia is a novel pathological phenomenon caused by new mechanisms. A simple inquiry into arterial morphology shows the opposite is true. The normal multi-layer cellular organization of the tunica intima is identical to that of diseased hyperplasia; it is the standard arterial system design in all placentals at least as large as rabbits, including humans. Formed initially as one-layer endothelium lining, this phenotype can either be maintained or differentiate into a normal multi-layer cellular lining, so striking in its resemblance to diseased hyperplasia that we have to name it "benign intimal hyperplasia". However, normal or "benign" intimal hyperplasia, although microscopically identical to pathology, is a controllable phenotype that rarely compromises blood supply. It is remarkable that each human heart has coronary arteries in which a single-layer endothelium differentiates early in life to form a multi-layer intimal hyperplasia and then continues to self-renew in a controlled manner throughout life, relatively rarely compromising the blood supply to the heart, causing complications requiring intervention only in a small fraction of the population, while all humans are carriers of benign hyperplasia. Unfortunately, this fundamental fact has not been widely appreciated in arteriosclerosis research and medical education, which continue to operate on the assumption that the normal arterial intima is always an "ideal" single-layer endothelium. As a result, the disease is perceived and studied as a new pathological event caused by new mechanisms. The discovery that normal coronary arteries are morphologically indistinguishable from deadly coronary arteriosclerosis continues to elicit surprise.

CONCLUSION

Two questions should inform the priorities of our research: (1) what controls switch the single cell-layer intimal phenotype into normal hyperplasia? (2) how is normal (benign) hyperplasia maintained? We would be hard-pressed to gain practical insights without scrutinizing our premises.

Versican degradation and vascular disease

Versican is an abundant proteoglycan in the blood vessel wall that is increased after vascular injury and accumulates in advanced atherosclerotic plaques. Versican is a large molecule with domains that mediate binding to cytokines, enzymes, lipoproteins, other extracellular matrix molecules, and signaling receptors. There is evidence that versican exists in the normal, as well as the diseased, vessel wall as discrete fragments, which represent these functional domains. We review the literature on versican degradation in vascular tissue and the function of versican domains, all of which suggest that proteolytic modification of versican may have physiologic as well as pathologic implications for the vascular system.

Long-term Results of Percutaneous Transluminal Angioplasty for Symptomatic Iliac In-stent Stenosis

OBJECTIVE

This study describes the long-term results of endoluminal therapy for iliac in-stent obstructions.

DESIGN

This is a retrospective study.

MATERIALS AND METHODS

From 1992 to 2005, 68 patients (22 women), with a mean age of 61+/- 13 years and 16 bi-iliac in-stent obstructions, underwent 84 endovascular interventions for focal iliac in-stent stenoses (n = 61) or occlusions (n = 23). Primarily, only uncovered stents were placed. All patients were symptomatic: 70% had disabling intermittent claudication, 23% had resting pain, and 7% had trophic changes. All had in-stent diameter reduction exceeding 50% that was confirmed by duplex scanning and angiography. Procedures were performed under local anesthesia via the femoral route.

RESULTS

All interventions were initially technically successful, with a minor complication of pneumonia in one patient (2%). Initial clinical success was achieved in 86% of patients. PTA alone was used to treat 72 (86%) in-stent obstructions, the other 12 (14%) had PTA and renewed stent placement. The 30-day mortality rate was 0%. Mean follow-up was 35 months (range, 3 months to 10 years) and included duplex scanning. Primary clinical patency was 88% at 1 year, 62% at 3 years, and 38% at 5 years follow-up. During follow-up, 28 (33%) of 84 extremities required secondary reinterventions because of symptomatic renewed in-stent stenosis, and 11 were treated successfully with repeated endovascular interventions. Secondary patency at 1 year was 94%, 78% at 3 years, and 63% at 5 years. Surgical intervention was eventually needed in 17 (20%) of the 84 extremities.

CONCLUSIONS

Endoluminal therapy for iliac focal in-stent obstructive disease seems to be a safe technique with acceptable long-term outcome and therefore a true alternative to primary surgical reconstruction.

Morphometric analysis of the intimal reaction after stent implantation in iliac arteries submitted to angioplasty in pigs

PURPOSE

To compare through digital morphometry, the intimal thickening of the common ilíac arteries (CIA) in pigs, submitted to angioplasty and angioplasty followed by stent implantation.

METHODS

Angioplasty was performed in 10 pigs in both CIA, followed by a stent implantation in the left CIA. After four weeks, the aorto-iliac segment was dissected. Histologic slices where divided in three groups: left CIA in the area of the proximal (group 1) and distal (group 2) implantation site of the stent and the region of angioplasty in the right CIA (group 3). The histological slices were digitalized to be analyzed by morphometry with calculation of the luminal, intimal and media layers areas. Descriptive statistics analysis was performed through average and standard deviation of areas on each group, using ANOVA, with LSD Post-Hoc test (p<0.05).

RESULTS

A significant statistic difference was observed when the median area of intimal layer of the groups 1 and 2 where compared with group 3 and in the media layer area of the groups 1 and 2 when compared with group 3. No difference was observed in luminal areas among the three groups.

CONCLUSION

Angioplasty followed by stent insertion produces an intimal thickening larger than that observed after simple angioplasty. However, the area of the media layer is smaller in the "angioplasty plus stent" group and there is no significant change in the luminal area among the three groups.

Bone morphogenetic protein 4: potential regulator of shear stress-induced graft neointimal atrophy

OBJECTIVE

Placement in baboons of a distal femoral arteriovenous fistula increases shear stress through aortoiliac polytetrafluoroethylene (PTFE) grafts and induces regression of a preformed neointima. Atrophy of the neointima might be controlled by shear stress-induced genes, including the bone morphogenetic proteins (BMPs). We have investigated the expression and function of BMPs 2, 4, and 5 in the graft neointima and in cultured baboon smooth muscle cells (SMCs).

METHODS

Baboons received bilateral aortoiliac PTFE grafts and 8 weeks later, a unilateral femoral arteriovenous fistula.

RESULTS

Quantitative polymerase chain reaction showed that high shear stress increased BMP2, 4, and 5 messenger RNA (mRNA) in graft intima between 1 and 7 days, while noggin (a BMP inhibitor) mRNA was decreased. BMP4 most potently (60% inhibition) inhibited platelet-derived growth factor-stimulated SMC proliferation compared with BMP2 and BMP5 (31% and 26%, respectively). BMP4 also increased SMC death by 190% +/- 10%. Noggin reversed the antiproliferative and proapoptotic effects of BMP4. Finally, Western blotting confirmed BMP4 protein upregulation by high shear stress at 4 days. BMP4 expression demonstrated by in situ hybridization was confined to endothelial cells.

CONCLUSIONS

Increased BMPs (particularly BMP4) coupled with decreased noggin may promote high shear stress-mediated graft neointimal atrophy by inhibiting SMC proliferation and increasing SMC death.

Accumulation and loss of extracellular matrix during shear stress-mediated intimal growth and regression in baboon vascular grafts

The composition of extracellular matrix during growth and regression of the neointima was analyzed during healing in a baboon aorto-iliac polytetrafluoroethylene graft. Graft neointimal thickening can be modulated by altering blood flow by construction of downstream arteriovenous fistulas. Normal flow with normal shear stress induces neointimal thickening, whereas high flow with high shear stress upstream of a fistula induces regression of established neointima. The neointima formed under normal shear stress is enriched in hyaluronan and proteoglycans, particularly versican. On the other hand, the neointima near the graft material is enriched in collagen and biglycan. Neointimal regression in response to high shear stress is associated with a loss of proteoglycans as detected by histochemical staining. Immunostaining with an antibody against an ADAMTS cleavage neoepitope of versican increases after switching to high flow, although immunostaining for versican core protein is not appreciably changed by high flow. The present data demonstrate that the graft neointima is enriched with proteoglycans, particularly versican and hyaluronan, as well as collagen, and there is a differential distribution of each. Neointimal atrophy occurs with an apparent loss of proteoglycans and evidence of versican degradation.

Accumulation and loss of extracellular matrix during shear stress-mediated intimal growth and regression in baboon vascular grafts

The composition of extracellular matrix during growth and regression of the neointima was analyzed during healing in a baboon aorto-iliac polytetrafluoroethylene graft. Graft neointimal thickening can be modulated by altering blood flow by construction of downstream arteriovenous fistulas. Normal flow with normal shear stress induces neointimal thickening, whereas high flow with high shear stress upstream of a fistula induces regression of established neointima. The neointima formed under normal shear stress is enriched in hyaluronan and proteoglycans, particularly versican. On the other hand, the neointima near the graft material is enriched in collagen and biglycan. Neointimal regression in response to high shear stress is associated with a loss of proteoglycans as detected by histochemical staining. Immunostaining with an antibody against an ADAMTS cleavage neoepitope of versican increases after switching to high flow, although immunostaining for versican core protein is not appreciably changed by high flow. The present data demonstrate that the graft neointima is enriched with proteoglycans, particularly versican and hyaluronan, as well as collagen, and there is a differential distribution of each. Neointimal atrophy occurs with an apparent loss of proteoglycans and evidence of versican degradation.

Early Surgical Outcome After Failed Primary Stenting for Lower Limb Occlusive Disease

PURPOSE

To evaluate the early results of revascularization after failed primary stent placement for lower limb occlusive disease.

METHODS

A retrospective review was conducted of 25 consecutive patients (16 men; mean age 65 years, range 32-89) treated between January 2001 to October 2003 for infrainguinal stent failure at a median 6.6 months (range 3-60) after primary stent implantation (27 femoropopliteal and 20 popliteal-crural) at referring hospitals. All surgical procedures for stent failure were performed at tertiary centers. The results of bypass grafting for failed stenting were compared to a contemporaneous cohort of patients undergoing primary bypass surgery performed by the same surgeons.

RESULTS

At the time of admission, 22 stents were thrombosed, and 3 patent stents presented with >50% in-stent stenosis. Twenty patients had 7 femoropopliteal or 9 femorodistal vein bypasses and 4 reconstructions of the common femoral or profunda femoris artery. Four patients had 3 primary amputations and 1 lumbar sympathectomy. One patient with claudication was treated conservatively. Procedure-related complications were observed in 40%; 30-day mortality was 4% (1/25). Early (30-day) graft thrombosis occurred in 6 (30%) of 20 arterial reconstructions, necessitating 8 secondary amputations (44% [11/ 25] overall amputation rate). A total of 47 surgical procedures were performed in the 24 surviving patients (median 2 operations per patient, range 1-9) over an 11-month period (range 1-57). Primary patency rates at 30 days and at 6 and 12 months were 67%, 44%, and 33%, respectively, in the poststent bypass cohort versus 98%, 96%, and 88%, respectively, in a contemporaneous group of patients treated with primary bypass grafting.

CONCLUSIONS

Failed stents in lower limb arteries often require distal reconstructive bypass surgery, which is associated with high complication rates and poor outcome, including major amputations. There is no scientific evidence to support stenting below the inguinal ligament.

Efeitos a curto prazo de "stents" não recobertos e recobertos com politetrafluoroetileno em aorta de suínos: um modelo experimental

OBJETIVO: Descrever um estudo experimental avaliando através da morfometria digital o espessamento intimal na parede arterial após o implante de "stents" metálicos auto-expansíveis recobertos ou não com politetrafluoroetileno (PTFE) na aorta de suínos. MÉTODOS: Em três grupos de suínos jovens uma bainha introdutora de 12 F foi inserida na aorta abdominal distal. Os animais do grupo I (n=5) foram considerados controle. Os animais do grupo II (n=10) receberam o implante de um stent metálico auto-expansível não recoberto. No grupo III (n=10) um stent auto-expansível recoberto com PTFE foi inserido. Após quatro semanas os animais foram sacrificados e os espécimes arteriais foram retirados, sendo o espessamento intimal quantificado pela análise morfométrica. RESULTADOS: Na comparação entre os grupos I, II e III quanto às áreas da íntima, média e índice intimal, não foi observada variação estatisticamente significativa. Diferenças foram observadas entre os grupos em relação às áreas luminais proximais (p=0,0036) e distais (p=0,044). Através dos testes de comparação múltipla para Kruskal-Wallis foi identificada uma diferença entre os grupos I e II. Entretanto, quando essas variáveis foram controladas pelo fator peso (relação área luminal/peso), a diferença não foi mais observada. CONCLUSÕES: Nesse estudo a curto prazo, o revestimento de PTFE não esteve associado a adicional espessamento intimal além daquele promovido pelo dispositivo metálico em artérias de grande calibre e condições de alto fluxo.

Operative management of carotid artery in-stent restenosis: first experiences and duplex follow-up

OBJECTIVES

Carotid Artery Stenting (CAS) may be comparable to Carotid Endarterectomy (CEA) as a durable and effective procedure in stroke prevention. Concern remains about the incidence of restenosis after stenting and its management. We evaluated the surgical management of restenosis after CAS.

DESIGN

prospective study.

METHODS

between December 1997 and April 2001, 217 CAS procedures were performed in 217 patients (155 men and 62 women; age 70 years +/- 8.2). After a mean of 8 months post-stenting four patients (two symptomatic, two asymptomatic with contralateral occlusion) with severe haemodynamic in-stent restenosis (90-99%) had surgical reintervention.

RESULTS

standard CEA with removal of the stent was performed in all four patients. No major complications occurred. Intima hyperplasia showed to be the predominant mechanism leading to in-stent restenosis. All four surgically treated patients remained asymptomatic and without recurrent restenosis over a mean follow-up time of 13 months (range 3-20 months).

CONCLUSION

the optimal treatment of in-stent restenosis has yet to be defined, but standard CEA with removement of the stent appears to be feasible.