Relation of plasma lipid and apoprotein levels to progressive intimal hyperplasia after arterial endarterectomy

Risk Factors for Carotid Restenosis in Patients After Eversion Endarterectomy vs Stenting: A Single-Center Experience

The primary aim of the presented study is to analyze and compare the rate of carotid restenosis in patients after eversion carotid endarterectomy (eCEA), primary carotid angioplasty and stenting (CASp), and stenting for carotid artery restenosis after previous eCEA (CASr). The secondary aim is to compare clinical outcomes in patients with carotid restenosis. The total number of patients with evident carotid restenosis was 223 (24.8%). In patients with eCEA, significant carotid restenosis rate was 12.7%, in the CASp group 18.7%, and CASr 6.7%. Patients with carotid restenosis were asymptomatic in 95.1% of cases. Patients in the CASp group experienced transient ischemic attack more than patients with eCEA (P = .007), while no difference was observed regarding cerebrovascular insult (CVI). The incidence of carotid restenosis was higher in CASp patients, and increased during the follow-up. The majority of patients are asymptomatic post-procedural and the degree of carotid restenosis does not correlate with the occurrence of postoperative symptoms. High low-density lipoprotein cholesterol (LDL-C) levels, low high-density lipoprotein cholesterol (HDL-C) levels, smoking, and a history of vascular surgery correlate with higher degrees of carotid restenosis. The most important factor in the prevention of carotid restenosis is risk factor control as well as adequate pharmacological therapy.

Frequency of restenosis after carotid endarterectomy

Introduction: Carotid artery restenosis is a significant long-term complication of carotid endarterectomy. Carotid artery restenosis is the result of neointimal hyperplasia in the early postoperative period or recurrent atherosclerotic lesions in the following period. Numerous studies have incriminated several risk factors as predisposing conditions for restenosis. The definite role of each predisposing factor, however, is still widely debated. Aim: Investigation of frequency and risk factors for restenosis after carotid endarterectomy. Material and methods: Data of 295 patients who underwent carotid endarterectomy was reviewed between 2008 and 2010. Postoperative duplex studies were performed on control examinations in the following period between 2011 and 2019. Retrospective analysis was performed to assess the effect of demographic, clinical and laboratory characteristics of patients on the development of restenosis after carotid endarterectomy. Results: Restenosis occurred in 76 (26%) patients after carotid endarterectomy, with the highest incidence during the third (33%) and fourth (25%) year of follow-up. Patients with diabetes (p = 0.048) and peripheral arterial occlusive disease (p = 0.041) had significant statistical correlation with the occurrence of restenosis, as well as parameters of lipid status - cholesterol values (p = 0.025), serum low-density lipoprotein (p = 0.036) and non highdensity lipoprotein (p = 0.041). Conclusion: The results of our study confirm the significant role of atherosclerotic risk factors in the development of carotid artery restenosis in the later postoperative period. More frequent monitoring and control of systemic risk factors in these patients is necessary in order to prevent the development of carotid artery restenosis.

Factors Affecting Recurrent Carotid Stenosis

Recurrent carotid stenosis is an ongoing process that may develop at or near the site of an operational or interventional procedure to treat an atheromatous stenosis. Although such a restenosis is most often initially without symptoms, as the disease progresses it may become symptomatic, and thus endanger the patient's life. Such patients are therefore candidates for revisional surgery. Extensive research investigation and numerous studies have incriminated several risk factors as predisposing conditions for recurrent carotid stenosis. The definite role of each predisposing factor, however, is still widely debated. Clarifying the extent of involvement of each factor in the pathogenesis of carotid restenosis is indeed demanding, as it would contribute enormously to the identification of the group of high-risk patients, and, therefore, determine the therapeutic approach in these patients.

3,3′-Dioctadecylindocarbocyanine-low-density lipoprotein uptake and flow patterns in the rabbit aorta–iliac bifurcation under three perfusion flow conditions

The aim of this study was to elucidate which of the following two factors plays a more important role in the localization of atherogenesis: the barrier function of the arterial endothelium modulated by wall shear stress or flow-dependent low-density lipoprotein (LDL) concentration at the blood/wall interface. To determine this, the rabbit aorto-iliac bifurcation was perfused with 3,3′-dioctadecylindocarbocyanine (DiI)-LDL solution under three different flow conditions: (i) forward flow (perfused in the in vivo flow direction); (ii) backward flow (perfused in a reversed flow direction); and (iii) static group (no flow). The results showed that there was a peak in the curve of DiI-LDL uptake distribution along the lateral wall of the bifurcation for all three groups, which was located in the branching areas where the endothelial cells were round and polygonal with no preferred orientation. Nevertheless, the peak of the forward flow group was much sharper than those of the other two groups. The overall DiI-LDL uptake was the highest for the static group. The present experimental study supports the concept that both the barrier function of the endothelium modulated by wall shear stress and the mass transport phenomenon of LDL concentration polarization are involved in the infiltration/accumulation of atherogenic lipids within the arterial wall. Nevertheless, the latter might play a larger role in the localization of atherogenesis.

Risk factors for lower-extremity vein graft failure

Lower-extremity vein graft failure causes significant morbidity, increases health care costs, and negatively impacts patient quality of life. Identification of risk factors is essential for patient selection, risk factor modification, and identifying individuals who would benefit from more stringent surveillance protocols. Risk factors can be considered as either patient-related or technical. Here we discuss the patient-related risk factors for vein graft failure. Nontechnical factors related to the indication for operation include operation after a previously failed graft, or redo bypass, critical limb ischemia, and infection. Risk factors for vein graft failure are distinct from the risk factors for cardiovascular events. Young age and African American and Hispanic race are risk factors for lower-extremity vein graft failure. Hypercoaguable and inflammatory states also increase risk for vein graft failure. Therapy with statins is indicated in patients with peripheral atherosclerosis and may have beneficial effects on vein graft function, although further studies are needed in this area.

Have statins changed the natural history of atheromatous disease and its treatment?

Statins are among the most widely prescribed medications in the world and there are now numerous clinical trials demonstrating the beneficial effects of these medications on the natural history of atheromatous disease and its treatment. There is now voluminous data to show that patients treated by vascular surgeons benefit from statins and that these medications do effect the natural history of atheroma, its consequences, and treatment. This article will attempt to summarize the more relevant data that highlights the beneficial effects of statins in patients with peripheral arterial disease and how use of these drugs affects cardio-, peripheral, and cerebrovascular risk.

The Role of Statin Drugs in the Management of the Peripheral Vascular Patient

The impact of statin therapy on established vascular conditions and recurrent disease is most relevant for long-term care. Patients receiving statin therapy have been shown to experience less recurrent stenosis following carotid endarterectomy and stent angioplasty, reduced cardiac events following cardiac and noncardiac vascular surgery, and reduction in aneurysm development. In patients with peripheral arterial disease, claudication distance is increased, as well as patency rates following infrainguinal arterial bypass grafting. Of note, statins drugs may also prove beneficial in the prevention of certain cancers, Alzheimer's disease, and osteoporosis (all diseases frequently seen concurrently in the patient with peripheral arterial disease). As such, it is becoming all the more necessary that vascular surgeons remain informed about clinical research initiatives related to statin use and lipid management in general. The following is a review of lipid metabolism as it applies to statins as well as a review of the beneficial effects of statins.

Apolipoprotein E Polymorphism and Stroke Subtypes in an Italian Cohort

BACKGROUND

Studies have indicated that apolipoprotein E (ApoE)-epsilon4 is a risk factor for ischemic cerebrovascular diseases (ICVD), but the existence of this association is still controversial. The aims of this study were: (1) to compare ApoE genotype and allele frequencies in Italian cases with ICVD and in healthy control subjects and (2) to compare ApoE allele frequencies among ischemic stroke subtypes.

METHODS

A hospital-based cohort of 302 Italian subjects with ICVD and 228 healthy subjects have been recruited to investigate the role of ApoE polymorphisms as risk factors for ICVD. TOAST criteria were employed to stratify ICVD cases by subtypes.

RESULTS

No significant differences in ApoE genotype and allele frequencies were found between cases and control subjects. The frequency of ApoE-epsilon4 was lower in cases than in control subjects (6% vs. 10.1%), although not significantly. No differences in ApoE genotype and allele frequencies were evident among ICVD subtypes. However, out of 36 ApoE-epsilon4 alleles 23 (3.7%) were found in subjects with ICVD related to primary degenerative arterial disease related to large vessel disease and small vessel disease, and 13 (2.1%) in remaining subjects. Using logistic regression analysis we assessed whether ApoE-epsilon4 allele was independently associated with risk of ICVD related to a primary degenerative arterial disease compared to other ICVD subtypes. While classical risk factors were significantly associated with higher risk for ICVD due to large vessel disease and small vessel disease than other ICVD subtypes, the role of ApoE-epsilon4 allele was not significant (OR 1.25, 95% CI 0.57-2.74).

CONCLUSION

Our study shows similar ApoE-epsilon4 genotype and allele frequencies in patients with ICVD and in control subjects. No differences were found among different ICVD subtypes either.

Determinants of carotid endarterectomy anatomic durability: Effects of serum lipids and lipid-lowering drugs

OBJECTIVES

Carotid endarterectomy (CEA) remains the gold standard for treatment of carotid stenosis. With inevitable comparisons of catheter-based therapy to all aspects of CEA, this study of a large contemporary series was undertaken to evaluate the determinants of anatomic durability of CEA.

METHODS

During the interval (1989 through 1999), 2,127 primary, isolated CEAs with selective patching (50.2%) were performed in 1,853 patients (61.8% male, 36.1% symptomatic). End points included patient longevity and perioperative morbidity as well as evidence of CEA anatomic durability as defined by duplex evaluation: CEA restenosis (moderate, >50%, or greater recurrent stenosis), which included CEA anatomic failure (severe, >70%, restenosis/carotid occlusion). The incidence of CEA recurrent stenosis was temporally assessed early (<2 years) and late (>2 years) after operation. Clinical and surgical variables potentially associated with the study endpoints were analyzed by univariate and multivariate methods.

RESULTS

The perioperative stroke and death rate was 1.4% and the 2-year and 10-year survival was 88.1% and 44.9%, respectively. Anatomic failure after CEA developed in 3.9% at 2 years and in 8.5% at 5 years; only 3.2% of CEA patients underwent reoperation during a mean follow-up of 73.4 months. Early (<2 years) analysis revealed 12.2% restenosis, whereas late (>2 years) results identified 9.8% progression of carotid stenosis and a 5.8% rate of anatomic failure. Multivariate analysis determined elevated creatinine (odds ratio [OR], 1.719, P < .001) and female gender (OR, 1.564; P < .02) correlated with early restenosis. Surgical patch closure and lipid-lowering drugs were protective for both early restenosis, with ORs of 0.543 (P < .0.001) and 0.601 (P < .007) and early anatomic failure ORs of 0.469 (P < .02) and 0.517 (P < .03), respectively. Although only elevated serum cholesterol (OR, 1.009; P < .03) correlated with late anatomic failure, only lipid-lowering drugs were protective for both late freedom from progression of disease (OR, 0.202; P < .0002) or late CEA anatomic failure (OR, 0.128; P < .0003).

CONCLUSIONS

The association of female gender and elevated cholesterol with recurrent carotid stenosis is confirmed, elevated creatinine is introduced as a risk factor, and surgical patch repair is protective for early CEA recurrent carotid stenosis. The unique findings of the significant, beneficial effects of lipid-lowering drugs on both early and late CEA anatomic durability and patient survival indicate that such therapy should be instituted in most patients after CEA.

Targeted replacement of mouse apolipoprotein A-I with human ApoA-I or the mutant ApoA-IMilano. Evidence of APOA-IM impaired hepatic secretion

Despite a pro-atherogenic profile, individuals carrying the molecular variant (R173C) of apolipoprotein (apo)A-I, named apoA-I(Milano) (apoA-I(M)), appear to be at reduced risk for cardiovascular disease. To develop an in vivo system to explore, in a controlled manner, the effects of apoA-I(M) on lipid metabolism, we have used the gene targeting technology, or "gene knock-in" (gene k-in), to replace the murine apoA-I gene with either human apoA-I or apoA-I(M) genes in embryonic stem cells. As in human carriers, mice expressing apoA-I(M) (A-I(M) k-in) are characterized by low concentrations of the human apolipoprotein and reduced high density lipoprotein cholesterol levels, compared with A-I k-in animals. The aim of the present study was to investigate the basic mechanisms of hypoalphalipoproteinemia associated with the apoA-I(M) mutation. ApoA-I and apoA-I(M) mRNA expression, as assessed by Northern blot analysis and quantitative real time reverse transcription-PCR, did not exhibit significant differences in either liver or intestine. Moreover, human apolipoprotein synthesis rates were similar in the k-in lines. When the secretion rate of the human apolipoproteins was assessed in cultured hepatocytes from the mouse lines, secretion from apoA-I(M)-expressing cells was markedly reduced (42% for A-I(M) k-in and 36% for A-I/A-I(M) k-in mice) as compared with that of A-I k-in hepatocytes. These results provide the first evidence that the hypoalphalipoproteinemia in apoA-I(M) human carriers may be partially explained by impaired apoA-I(M) secretion.

Antibodies to cardiolipin may increase the risk of failure of peripheral vein bypasses

OBJECTIVES

To assess the association between antibodies to cardiolipin and infrainguinal vein graft patency.

MATERIALS AND METHODS

Plasma levels of antibodies to cardiolipin, haemostatic factors, lipids and the smoking marker carboxyhaemoglobin were determined preoperatively and 6 weeks postoperatively in 80 patients undergoing infrainguinal vein bypass surgery. Bypass patency was assessed by ankle blood pressure measurements and ultrasound duplex scanning at 1 week, 6 weeks, 3, 6, 9 and 12 months. A localised increase in the graft peak systolic velocity by a factor of 2.5 or more was considered to indicate a significant stenosis.

RESULTS

Antibodies to cardiolipin were identified in seven (9%) patients preoperatively. In four of these seven patients the bypasses thrombosed within 3 months after surgery and another two developed stenoses. At 6 months the primary bypass patency, i.e. patency without stenosis, was 14% (95% confidence interval (CI) 0-33%) in patients with antibodies to cardiolipin, as opposed to 57% (95% CI 45-69%) in patients without these antibodies (log rank test: p = 0.03). Diabetes mellitus was also associated with a reduced 6 months primary bypass patency (38% (95% CI 16-60%) vs. 58% (95% CI 45-71%), p = 0.006). A Cox regression analysis showed that both the presence of antibodies to cardiolipin and diabetes independently contributed towards predicting the overall risk of bypass failure.

CONCLUSION

Antibodies to cardiolipin were identified in 9% of patients undergoing infrainguinal vein bypass surgery and appeared to be associated with increased risk of bypass failure.

Duplex imaging findings predict stenosis after carotid endarterectomy

PURPOSE

This study was performed to determine whether early duplex findings predicted restenosis after carotid endarterectomy.

METHODS

One hundred ninety-two symptomatic patients who underwent carotid endarterectomy were studied with color duplex imaging at 1 day and 1 week after surgery to identify minor residual disease (causing < 50% stenosis), arterial kinking, and suture stricture, and to measure the external and luminal diameters of the carotid bulb and distal internal carotid artery. Patients were then observed prospectively with duplex surveillance for a median of 24 months to identify > 50% restenosis.

RESULTS

Twenty-five stenoses > 50% of the operated carotid artery (13%) were identified, four at 1 day (residual) and 21 at a median follow-up of 6 months (restenosis). On multiple logistic regression analysis, > 50% restenosis was found to be associated with minor day-1 residual stenosis (p = 0.01) and with small luminal diameter of the distal internal carotid artery (p = 0.03) as measured 1 week after carotid endarterectomy. Life table analysis showed restenosis at 24 months to be more common for patients with below-median than patients with above-median carotid bulb external diameter (18% vs 5%, respectively; p = 0.01).

CONCLUSIONS

Duplex scanning within a week of carotid endarterectomy identifies > 50% residual stenosis, in addition to minor residual 25% to 50% stenosis and small carotid dimensions, which are good predictors of > 50% restenosis at 6 months.

Vessel wall and flow characteristics after carotid endarterectomy: eversion endarterectomy compared with Dacron patch plasty

OBJECTIVES

Experimental studies have demonstrated that decreases in vessel wall compliance and increases in turbulence may contribute to (re)stenosis. We studied vessel wall and flow characteristics after endarterectomy with Dacron patch plasty and after eversion endarterectomy, and compared those findings with the characteristics of non-stenotic, unoperated carotid arteries (controls).

METHODS

Seventy-four patients who underwent 84 carotid endarterectomies were studied postoperatively by ultrasonography (2-24 months) Recorded variables included the diameter of the bulb, strain, elastic modulus (stiffness), and presence of turbulent flow.

RESULTS

The vessel wall and flow characteristics of the two groups differed significantly. The diameter was higher and the strain lower in Dacron patch plasty than in controls; eversion endarterectomy did not differ from controls. The elastic modulus was higher (stiffer) in Dacron patch plasty than in eversion endarterectomy; neither Dacron patch plasty nor eversion endarterectomy differed significantly from controls. The stiffness index was not significantly different between the groups. Turbulence was present in Dacron patch plasty and eversion endarterectomy when compared with controls.

CONCLUSION

In diameter, strain and stiffness, the operated carotid artery resembles the non-stenotic, unoperated artery more closely after eversion endarterectomy than after Dacron patch plasty.

Growth-stimulating effect of lipoproteins on human arterial smooth-muscle cells and lung fibroblasts is due to apo B-containing lipoproteins, type LDL and VLDL, and requires LDL receptors

Excessive growth of the arterial smooth muscle is essential for the development of atherosclerosis and leads to arterial insufficiency in several other conditions. It is therefore important to elucidate the mechanisms that regulate the growth of the human arterial smooth-muscle cell, SMC. Like other untransformed cells, SMC require plasma for sustained growth in vitro. As found in an earlier study most of the material in plasma which stimulates SMC growth is related to the lipoproteins (LP), and is widespread among LP of different density classes. In the present study we investigated whether the growth-stimulating activity might be more specifically related to certain lipoproteins defined by criteria other than density or particle size. Activity was assayed using human SMC and human lung fibroblasts as both a change of culture size and DNA synthesis. The growth-stimulating activity was confined to apo B-containing LP, as defined by their strong affinity to heparin-Sepharose, electrophoretic beta-mobility, the presence of apo B and the absolute requirement of low density lipoprotein (LDL) receptors for the growth-stimulating effect to appear. It was strongly potentiated by PDGF-BB. A much higher level of LDL was required to initiate synthesis of DNA in SMC than in fibroblasts but at optimal LDL concentration the degree of activation was similar for both cell types. Apo B-containing LP are very powerfully related to atherosclerosis. As intimal thickening is a primary change in atherogenesis, the growth-stimulating effect of them may be of direct pathogenetic importance.

Microsomal enzyme inducers raise plasma high-density lipoprotein cholesterol levels in healthy control subjects but not in patients with primary hypoalphalipoproteinemia

In this study we compared the ability of phenytoin, a microsomal enzyme inducer, to raise plasma high-density lipoprotein (HDL) levels in normolipidemic subjects and patients with primary hypoalphalipoproteinemia. In healthy control subjects, phenytoin caused a dose-dependent increase of plasma HDL, HDL2, and HDL3 cholesterol levels, up to 40% to 50%. Minor changes were recorded in the plasma concentrations of apolipoprotein (apo) A-I and apo A-II; the plasma level of the cholesteryl ester transfer protein (CETP) decreased by 42%. In contrast, none of the patients with hypoalphalipoproteinemia had changes in plasma HDL, HDL2, or HDL3 cholesterol, apo A-I, apo A-II, or CETP levels. These findings indicate that microsomal enzyme inducers are unsuitable to increase plasma HDL levels in high-risk patients with primary hypoalphalipoproteinemia, and they disclose a new mechanism, that is, decreased CETP-mediated transfer of cholesterol out of HDL, for the HDL-raising effect of microsomal enzyme inducers in healthy individuals.

Drug control of reverse cholesterol transport

Reverse cholesterol transport identifies a series of metabolic events resulting in the transport of excess cholesterol from peripheral tissues to the liver. High-density lipoproteins (HDL) are the vehicle of cholesterol in this reverse transport, a function believed to explain the inverse correlation between plasma HDL levels and atherosclerosis. An attempt to stimulate, by the use of drugs, this transport process may hold promise in the prevention and treatment of arterial disease. Among the agents affecting lipoprotein metabolism, only probucol exerts significant effects on reverse cholesterol transport, by stimulating the activity of the cholesteryl ester transfer protein and, consequently, altering HDL subfraction composition/distribution. Another approach to the stimulation of reverse cholesterol transport consists of raising plasma HDL levels; studies in animals, either by exogenous supplementation or by endogenous overexpression, have shown a consistent benefit in terms of atherosclerosis regression and/or non-progression. Thus, it is time to consider different future treatments of atherosclerosis, combining the classical lipid-lowering treatments with innovative methods to promote cholesterol removal from the arterial wall.

The influence of smoking and lipids on restenosis after carotid endarterectomy

Factors associated with restenosis were investigated in 107 patients undergoing carotid endarterectomy for symptomatic disease. The patients, 71 men and 36 women with mean age 68 +/- 8 years, were followed up for 1 year by serial Duplex scanning. Carotid restenosis of > or = 50% developed in 18 patients (17%), 11 men and seven women. Restenosis was not influenced by age, sex, diabetes or hypertension. Continuing smokers, serum cotinine > 200 nmol/l, had a significantly higher incidence of > or = 50% restenosis after 1 year (39%), compared with only 16% of non-smokers, p = 0.023. Restenosis > or = 50% also was associated significantly with below median body mass index (p = 0.027). Women undergoing carotid endarterectomy had higher levels of cholesterol (median 7.4 mmol/l) and apolipoprotein B (median 0.81 g/l) than men (median cholesterol 6.4 mmol/l, median apolipoprotein B 0.69 g/l), p < 0.01. For men only, restenosis of > or = 50% was associated with low levels of serum cholesterol (median 5.7 mmol/l), p = 0.002. For women cholesterol levels were higher (median 8.1 mmol/l) in those with > or = 50% restenosis. Smoking adversely influences early restenosis (1 year) after carotid endarterectomy. Hyperlipidaemia is not a risk factor for restenosis in men, but may be associated with restenosis in women.