Pathogenesis Of Peripheral Arterial Disease Research Articles

Abstract 126: Genome Wide Association Study in the Million Veteran Program Identifies a Novel Role for Thrombosis in the Pathogenesis of Peripheral Artery Disease

Introduction: PAD is a leading cause of cardiovascular morbidity and mortality. Previously published GWAS have been limited by small sample sizes and have only identified 3 genome-wide significant (P<5x10 -8 ) risk loci to date. Hypothesis: DNA sequence variants affecting multiple biological pathways are associated with PAD risk. Methods: Using electronic health record data, we identified individuals with and without clinical PAD from the 353,323 Million Veteran Program (MVP) participants genotyped on a customized Affymetrix Biobank array. We tested 32 million genotyped and imputed DNA variants for association with clinical PAD separately in participants of European (EUR), African (AFR), and Hispanic (HIS) ancestry using logistic regression models controlling for age, sex and population structure, and then performed trans-ethnic meta-analysis. The results were replicated with data from the UK Biobank. Results: We identified 31,307 individuals (24,009 EUR, 5,373 AFR, 1,925 HIS) with, and 211,753 individuals without, PAD. Following meta-analysis and replication, there were 19 genome-wide significant risk loci associated with PAD. We replicated a known association at 9p21 (P=4.3 x10 -39 ), and identified several novel loci associated with PAD that were previously known to be associated with atherosclerosis ( LPA , HDAC9 ), diabetes ( TCF7L2 ), lipid levels ( LPL , CELSR2 ), and tobacco use ( CHRNA3 ). We also identified a novel association with PAD for the Factor V Leiden (FVL) mutation (OR 1.20, P=1.6x10 -12 ), which remained significant after controlling for venous thromboembolism (OR 1.10, P=8.7x10 -4 ). Sensitivity analysis demonstrated FVL is associated with increasing risk estimates for PAD severity (claudication OR 1.19, P=0.0012; rest pain OR 1.41, P=0.004; tissue loss OR 1.57, P=7x10 -9 ). Conclusions: Using the MVP, we assembled the largest reported cohort of individuals with clinical PAD and genetic data worldwide. Our data replicate known causal risk factors and identify a novel association for FVL and its putative role for thrombosis in the development of clinical PAD.

Abstract 233: Genetic Evidence for Overlap in the Pathogenesis of Peripheral Artery Disease and Coronary Artery Disease

Introduction: Peripheral artery disease (PAD) is thought to share atherosclerotic biologic mechanisms and traditional risk factors with coronary artery disease (CAD). Although significant progress has been made in identifying genetic contributors to CAD, genetic factors underlying PAD remain largely uncharacterized. The aim of our study was to evaluate the shared genetic architecture between PAD and CAD. Hypothesis: DNA sequence variants associated with CAD risk are also associated with PAD. Methods: We analyzed the electronic health records from 239,621 U.S. Veterans of European ancestry with available imputed genetic data from the VA Million Veteran Program. Within this cohort we identified 16,364 participants with PAD, and 67,636 with CAD. We constructed additive weighted genetic risk scores (GRS) of 57 DNA sequence variants previously associated with CAD at genome-wide significance. We standardized the GRS to have a mean of zero and standard deviation (SD) of 1, and assessed the strength of its association with PAD through logistic regression. Models were adjusted for age, sex, and 7 principal components of ancestry. In a mediation analysis, we then included CAD status in the model to examine if these genetic associations remained significant after accounting for a CAD diagnosis. Results: The CAD GRS was significantly associated with clinical CAD [OR = 1.22 per SD increase in GRS, (95%CI: 1.21 -1.23, Z-Score = 44.5, P < 2 x10 -16 )]. The CAD GRS was also significantly associated with PAD [OR = 1.12 per SD increase in GRS, (95%CI: 1.10-1.14, Z-Score = 14.5, P < 2x10 -16 )]. This magnitude of association was attenuated when further adjusting for CAD in the regression model but remained strongly significant [OR = 1.05 per SD increase in GRS, (95%CI: 1.03-1.07, Z-Score = 6.2, P = 5.6x10 -10 )]. Conclusions: In the largest single cohort of CAD and PAD cases worldwide, we found that a genetic risk score of DNA sequence variants associated with risk for CAD are also associated with risk of PAD, even after accounting for the presence of coronary atherosclerosis. These data suggest significant overlap in the mechanisms underlying development of atherosclerosis within both the peripheral and coronary arterial beds.

Correlations of Endogenous Testosterone and DHEA-S in Peripheral Arterial Disease

Abstract Background: there is an overt bias between cardiovascular morbidity and mortality in male and female patients. Research of the past decades postulated that this difference could be due to the lipid-lowering effect of male sexual-steroids, that show decreased values in cardiovascular disease. Methods: the aim of our study was to determine total serum testosterone and dehydroepiandrosterone sulfate (DHEA-S) on a peripheral arterial disease patient’s cohort (n=35), in comparison with a healthy control group, (n=23) and to establish correlations with other biological risk factors like serum lipids, C-reactive protein, plasma fibrinogen, and the ankle-brachial pressure index. Results: our results showed that total serum testosterone and DHEA-S were significantly decreased in PAD patients in comparison to the control group. We could not observe any significant correlation with the presence of critical ischemia, the levels of total cholesterol, HDL-cholesterol, triglycerides, lipoprotein (a), C-reactive protein or plasma fibrinogen. Conclusion: these results express that low androgen levels could be implicated in the pathogenesis of peripheral arterial disease, but testosterone and DHEA-S are not markers of disease severity. The elucidation of their exact role needs larger, population-based studies.

RNASEQ IDENTIFIES DIFFERENTIAL EXPRESSION OF PLATELET TRANSCRIPTS IN SUBJECTS WITH PERIPHERAL ARTERY DISEASE

Platelets play an important role in the pathogenesis of peripheral artery disease (PAD), and inhibition of platelet activity reduces cardiovascular events. We hypothesized that subjects with PAD would have a unique platelet transcription profile compared to subjects without PAD. Ten subjects with

Impact of Fibroblast Growth Factor-23 on Peripheral Arterial Disease in Type 2 Diabetes Mellitus: A Comparative Cross-Sectional Pilot Study

Purpose: To evaluate whether fibroblast growth factor-23 (FGF-23) has a common role in the pathogenesis of peripheral arterial disease (PAD) and chronic kidney disease (CKD) in type-2 diabetes mellitus (DM). Material and Method: Twenty-one patients with diabetic nephropathy composed the diabetic nephropathy (DM-NP) group and 20 subjects with DM but without NP constituted the DM group. The control group was comprised of 10 ageand gender-matched non-diabetic individuals with CKD. Results: FGF-23 levels were similar in DM-NP and CKD groups (p=0.5). Both groups had higher FGF-23 levels compared to DM group (p<0.001 and p=0.007). PAD was more common in DM than in CKD (p=0.03). In all cases involving DM (e.g., both the DM-NP and DM-groups), FGF-23 levels did not vary with arterial wall changes recorded via Doppler ultrasonography (p=0.5). Discussion: NP and PAD may be independent complications of DM. In DM, FGF-23 may be a marker of NP but not of PAD.

Abstract 16718: Energy Induced Vasodilation in a Model of Endothelial Dysfunction Requires Nitric Oxide

Introduction: Over 8 million Americans are treated for peripheral artery disease (PAD), i.e. intermittent claudication, impaired wound healing, and critical limb ischemia. Endothelial dysfunction of the microcirculation is a potential mechanism for the pathogenesis of PAD because risk factors for PAD- age, hypertension, atherosclerosis, diabetes mellitus, and active tobacco use, have been directly related to a reduction in NOS expression and NO production. These reductions in NO bioavailability impair flow mediated dilation of the brachial artery and acetylcholine induced vasodilation. We have shown energy (670 nm (R/NIR)) can increase NO independent of NOS through release of NO from nitrosyl-heme stores. We hypothesized R/NIR can stimulate vasodilation, and serve as a potential therapy to recover vasodilation in a model of endothelial dysfunction (db/db mice). Methods: Human dermal microvascular endothelial cells (HMVEC) loaded with DAF-2 were stimulated with R/NIR 100mW/cm2 up to 6J. NO was measured using HPLC of DAF-2T. To test vasodilation, facial arteries from C57Bl/6 and db/db mice were isolated, pressurized to 60mmHg, and pre-constricted with U46619. The vessels were irradiated with 670 nm light (10mW/cm2) for 5 min with 10 min dark period between irradiation. Results: HMVEC stimulated with R/NIR increased NO 28.3% (±11.2, p&lt;0.05). The NO scavenger c-PTIO inhibited R/NIR (17.0%±5.9, p&lt;0.05) but was unchanged by pre-incubation with NOS inhibitor L-NAME (1mM) (13.1% ± 5.6). Vessel diameter increased up to 17.8% (±3, p&lt;0.05) after 5 min with R/NIR. L-NAME did not affect dilation (13.74% ±2.2), however c-PTIO (100μM) could attenuate dilation (-.51% ± 1.1, p&lt;0.001). R/NIR vasodilation was abolished with vessel denudation (1.2%± 2.21, p&lt;0.001), suggesting R/NIR dilation was endothelial dependent. Impaired dilation in db/db mice was reversed, as R/NIR could significantly dilate db/db vessels after 5 min [(13.7% ± 2.8) vs. control (17.8% ±3)]. Conclusion: R/NIR vasodilation requires intact endothelium and NO, but does not require NOS. In an obesity model of endothelial dysfunction, R/NIR can significantly restore vasodilation. Therefore, R/NIR as a source for therapeutic NO should be strongly considered in the treatment of ischemic wounds.

High prevalence of peripheral arterial disease in patients with obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) merits increasing attention as cardiovascular risk factor. Whereas carotid and coronary artery disease have been associated with OSA, occurrence of peripheral arterial disease (PAD) in OSA remains undefined. We screened 100 patients with suspected OSA for PAD. After polysomnography, each patient underwent standardized angiological testing including ankle-brachial index (ABI), central pulse wave velocity, pulse wave index and duplex sonography. Among total study population, PAD prevalence accounted for 88%, of those 68% had asymptomatic plaques and 20% were symptomatic Fontaine ≥ IIa. In confirmed OSA, prevalence raised up to 98%. Except for smoking habits, distribution of established risk factors did not differ between OSA groups (patients without, mild, intermediate and severe OSA). Presence of plaque, Fontaine PAD stages and intermittent claudication exhibited significant gain with increasing AHI. A logistic regression model revealed that age (OR = 1.199, 95% CI [1.066; 1.348]) and the logarithmically transformed AHI (OR = 5.426, 95% CI [1.068; 27.567]) had the strongest influence on plaque presence. Central pulse wave velocity as marker of arterial stiffness was positively correlated with AHI. OSA is associated with a high prevalence of PAD. This implies substantial diseasés under-recognition and a presumable atherogenic role of OSA in the pathogenesis of PAD. However, vasoprotective impact of OSA treatment remains to be determined.

Therapeutic angiogenesis improves fibrinolytic imbalance in patients with critical limb ischemia

The mechanisms of fibrinolysis have been suggested to be linked to the pathogenesis of peripheral artery disease. The impact of therapeutic angiogenesis on the parameters of fibrinolysis was studied in critical limb ischemia (CLI). CLI patients (N = 29) and blood donors as controls (N = 29) were enrolled. Bone marrow (600 ± 50 ml) was centrifuged (3200g, 20 min, 22°C), bone marrow-derived mononuclear cells (100-120 ml) were separated by Optipress I and implanted into the ischemic limb using intramuscular injections. ELISA was employed for the assessment of plasma tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) levels. Patients were followed-up prior to the procedure and after 1, 3 and 6 months. All stage-IV patients (N = 22) had ischemic lesions. The lesions resolved in 10 patients. Five patients underwent major amputation; they all were stage-IV. Ischemic lesions persisted in seven patients beyond 6 months. The t-PA levels were higher in patients compared with the healthy controls both at baseline (P < 0.01) and after 6 months (P < 0.05). No significant changes were observed in the t-PA levels during the follow-up. PAI-1 was higher in patients than in the healthy individuals at baseline (P < 0.001) and at month 1 (P < 0.05). However, no difference in PAI-1 levels between the patients and the healthy individuals was found after 3 and 6 months. The PAI-1 levels were significantly downregulated during the follow-up compared with the baseline (P < 0.0001). Therapeutic angiogenesis for the CLI downregulates PAI-1 levels, thus having a systemic effect on fibrinolysis.

Identification of candidate target genes forhuman peripheral arterial disease using weighted gene co‑expression network analysis.

The aim of the present study was to identify the potential treatment targets of peripheral arterial disease (PAD) and provide further insights into the underlying mechanism of PAD, based on a weighted gene co‑expression network analysis (WGCNA) method. The mRNA expression profiles (accession.no.GSE27034), which included 19samples from patients with PAD and 18samples from normal control individuals were extracted from the Gene Expression Omnibus database. Subsequently, the differentially expressed genes (DEGs) were obtained using the Limma package and the co‑expression network modules were screened using the WGCNA approach. In addition, the protein‑protein interaction network for the DEGs in the most significant module was constructed using Cytoscape software. Functional enrichment analyses of the DEGs in the most significant module were also performed using the Database for Annotation, Visualization and Integrated Discovery and Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology‑Based Annotation System, respectively. A total of 148DEGs were identified in PAD, which were used to construct the WGCN, in which two modules (gray module and turquoise module) were identified, with the gray module exhibiting a higher gene significance (GS) value than the turquoise module. In addition, a co‑expression network was constructed for 60DEGs in the gray module. The functional enrichment results showed that the DEGs in the gray module were enriched in five Gene Ontology terms and four KEGG pathways. For example, cyclin‑dependent kinase inhibitor1A (CDKN1A), FBJ murine osteosarcoma viral oncogene homolog (FOS) and prostaglandin‑endoperoxide synthase2 (PTGS2) were enriched in response to glucocorticoid stimulus. The results of the present study suggested that DEGs in the gray module, including CDKN1A, FOS and PTGS2, may be associated with the pathogenesis of PAD, by modulating the cell cycle, and may offer potential for use as candidate treatment targets for PAD.

Monocyte Chemoattractant Protein 1 Is Correlated With Glycemic Control and Peripheral Arterial Disease in Type 2 Diabetic Patients With Metabolic Syndrome

We evaluated the serum levels of monocyte chemoattractant protein 1 (MCP-1) and their association with peripheral arterial disease (PAD) in 199 patients with type 2 diabetes mellitus (T2DM) and metabolic syndrome ([MetS], group A) in comparison with 109 healthy controls (group B). In group A, MCP-1 levels were significantly (P < .001) higher than group B and exhibited a positive correlation with HbA1c (P < .001) and a negative correlation with ankle-brachial index (P < .001). In the same group, patients with PAD had significantly higher MCP-1 levels compared with those without PAD (P < .001). In conclusion, T2DM patients with MetS exhibit higher serum MCP-1 levels. The latter is associated with worse glycemic control and PAD. These results suggest a potential contributory role for MCP-1 in the pathogenesis of PAD in the presence of hyperglycemia and MetS in T2DM.

Peripheral Arterial Disease in Diabetes: Is There a Role for Genetics?

Atherosclerotic occlusion of vessels outside of the heart is commonly referred to as peripheral arterial disease (PAD). The lower extremity is the most common site of PAD and its development is associated with the same risk factors involved in general atherosclerosis. However, there is emerging evidence that other risk factors may play a key role in the development of PAD. Over the past decade polymorphism in a number of genes has been shown to contribute to the risk of developing PAD. These genes can be classified into proartherosclerosis or proatherothrombosis based on the known gene function. Moreover, they can be categorized as "novel" polymorphism when the function of the genes is not known or when the specific gene within an associated genetic locus is not known. It is intriguing that not only are gene polymorphisms associated with PAD being identified, but more recently studies are now finding gene polymorphisms that may be important in development of this syndrome only in the contest of certain environmental factors such as diabetes. Currently how these gene-environment interactions contribute to the pathogenesis of PAD is poorly understood but will likely play a critical role in future understanding of this complex disease.

Abnormal plasma fibrin clot characteristics are associated with worse clinical outcome in patients with peripheral arterial disease and thromboangiitis obliterans

BackgroundA role of blood coagulation in the pathogenesis of peripheral arterial disease (PAD) and Buerger's disease, or thromboangiitis obliterans (TAO), remains unclear. ObjectiveTo test the hypothesis that PAD and TAO are associated with prothrombotic phenotype of a fibrin clot. Patients and methodsEx vivo plasma fibrin clot permeability, turbidimetry and efficiency of fibrinolysis were investigated in 106 patients with PAD and 20 patients with TAO and compared with the respective control groups matched for age, sex, and cardiovascular risk factors. The progression of PAD and TAO were evaluated during follow-up of 3–7.5 years. PAD patients were characterized by lower clot permeability (−18.8%, p=0.005), shorter lag phase (−35.3%, p<0.001), higher maximum clot absorbancy (+22.4%, p<0.001), prolonged clot lysis time (+30.6%, p=0.003), and lower rate of D-dimer release from clots in the presence of recombinant tissue plasminogen activator (−16.5%, p=0.009), but twofold lower maximum D-dimer levels released from clots during lysis (p<0.001) than the controls. Similar, but more pronounced abnormalities were observed in TAO patients versus controls (all p<0.01). Seventeen PAD (16%) and 3 (15%) TAO patients were lost to follow-up. The progression observed in 47 (52.8%) PAD patients and 10 (59%) TAO patients was associated with lower clot permeability (−14.6%, p=0.009, and −17.5%, p=0.02) and prolonged clot lysis (+11.3%, p=0.004, and +12.4%, p=0.03, respectively). ConclusionsUnfavorably altered fibrin clot properties are observed in both PAD and TAO. Denser fibrin clots with reduced susceptibility to lysis might characterize the progression of both diseases during long-term follow-up.

Polymorphisms of the hypoxia-inducible factor 1 gene and peripheral artery disease

Hypoxia-inducible factor 1 (HIF1) is a key regulator of angiogenesis and is involved in inflammation, which are two important features of the pathogenesis of peripheral artery disease (PAD). The gene for the HIF1-alpha subunit (HIF1A) carries two common mis-sense mutations, P582S (C>T, rs11549465) and A588T (G>A, rs11549467), which both have been related to increased trans-activation capacity of HIF1-alpha. The aim of the present study was to analyze the role of these polymorphisms in PAD. The study was designed as a case-control study including 917 patients with documented PAD and 969 control subjects. HIF1A genotypes were determined by exonuclease (TaqMan) assays. HIF1A P582S genotype frequencies were not significantly different between PAD patients (PP 82.2%; PS 16.5%; SS 1.3%) and control subjects (83.2%; 15.3%; 1.5%; p = 0.72). Similarly, HIF1A A588T genotype frequencies did not differ significantly between PAD patients (AA 95.9%; AT 4.1%) and control subjects (AA 96.8%; AT 3.2%; p = 0.28). In a multivariate logistic regression analysis including age, sex, smoking, diabetes, arterial hypertension and hypercholesterolemia, neither the HIF1A P582S polymorphism (odds ratio: 1.26; 95% confidence interval 0.92-1.74; p = 0.16) nor the A588T polymorphism (odds ratio: 1.17; 95% confidence interval 0.59-2.35; p = 0.66) was significantly associated with the presence of PAD. Both polymorphisms were furthermore not associated with age at onset of PAD, Fontaine stage of the disease or the ankle/brachial index of patients. We conclude that functional polymorphisms in the HIF1A gene do not contribute to susceptibility to PAD.

Does endothelial dysfunction contribute to the clinical status of patients with peripheral arterial disease?

Peripheral arterial disease leads to lower extremity ischemia and limb loss, and is linked to cardiovascular events. The anatomical extent of lower extremity atherosclerosis fails to fully explain ischemic symptoms or predict the development of critical limb ischemia. Endothelial dysfunction is known to contributed to the pathogenesis and clinical expression of coronary artery disease, but the importance of endothelial dysfunction in peripheral arterial disease remains incompletely understood. Endothelial dysfunction could contribute to lower extremity ischemia by impairing blood flow responses to ischemia, collateral formation and arterial remodelling, and by promoting vasospasm, thrombosis, plaque rupture and lesion progression. There is a need for additional studies examining the contribution of endothelial dysfunction to the pathogenesis of peripheral arterial disease, and the potential role of endothelial dysfunction as a surrogate marker with utility in the management of patients.

The MTP −493TT genotype is associated with peripheral arterial disease: Results from the Linz Peripheral Arterial Disease (LIPAD) Study

Objectives Microsomal triglyceride transfer protein (MTP) transfers lipids into apoprotein B-containing lipoproteins for secretion from liver, intestine, and heart. We hypothesized the −493T single nucleotide polymorphism in the MTP promoter region to be associated with altered lipoprotein levels and with presence of peripheral arterial disease (PAD). Design and methods 433 patients with symptomatic PAD and 433 controls matched for sex and age from the Linz Peripheral Arterial Disease (LIPAD) study were genotyped cross-sectionally for the −493T single nucleotide polymorphism in the promoter region of the MTP gene. Results The frequency of the −493T allele in patients with PAD was 0.320, whereas it was 0.255 in controls ( p < 0.001). The MTP −493TT genotype was independently associated with PAD, even after adjustment for LDL cholesterol. The odds ratio of the −493TT MTP genotype for PAD was 3.18 (95% CI, 1.76–5.71) when adjusted for current smoking, arterial hypertension, LDL cholesterol, triglycerides, glycohemoglobin, C-reactive protein, and homocysteine. Furthermore, we found an association between the MTP promoter polymorphism and the apolipoprotein B-containing lipoproteins total-cholesterol ( p = 0.011), LDL cholesterol ( p = 0.002) and apolipoprotein B ( p = 0.034). Conclusions Our results provide preliminary evidence for a potential role of the MTP −493TT genotype in the pathogenesis of PAD.

The LPA gene C93T polymorphism influences plasma lipoprotein(a) levels and is independently associated with susceptibility to peripheral arterial disease

BackgroundPlasma lipoprotein(a) [Lp(a)] levels are mainly genetically determined. The C93T polymorphism is a naturally occurring variant of the LPA gene that may influence Lp(a) concentration. The role of Lp(a) in the pathogenesis of peripheral arterial disease (PAD) has not been firmly established. MethodsA total of 299 patients with PAD and 312 PAD-free control subjects were investigated. Genotyping of the LPA C93T polymorphism was performed by means of PCR-RFLPs. Plasma Lp(a) levels were determined by ELISA. ResultsSubjects carrying at least one LPA 93T allele had lower Lp(a) levels. The prevalence rate of the 93T allele was significantly higher in control subjects (19.5%) than in PAD patients (13.0%, P=0.012). In multivariate logistic regression analysis with covariates including traditional risk factors, the 93T allele was independently associated with a reduced risk of PAD (OR=0.75, 95% CI=0.51-0.95, P=0.031). ConclusionThe 93T allele of the LPA gene is associated with a reduced risk of PAD and low Lp(a) levels.

Basement Membrane Remodeling in Skeletal Muscles of Patients with Limb Ischemia Involves Regulation of Matrix Metalloproteinases and Tissue Inhibitor of Matrix Metalloproteinases

Background/Aim: Because the pericapillary basement membrane in skeletal muscles of patients with chronic critical limb ischemia (CLI) is thickened, we determined the expression patterns of genes involved in collagen metabolism, using samples from 9 CLI patients, 4 patients with acute limb ischemia and 4 healthy controls. Methods: Gene array analysis, quantitative RT-PCR and semiquantitative grading of immunohistochemical reactivity were performed to determine mRNA/cDNA and protein concentrations. Results: In CLI patients compared to controls, cDNA levels of matrix metalloproteinase (MMP)-9 and MMP-19 were higher, collagen type IV chains A1 and A2, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 were similar and MMP-2 were lower. On the protein level, MMP-2, MMP-9, MMP-19 and TIMP-1 were more abundantly expressed. In skeletal muscles from patients with acute limb ischemia, cDNA and protein levels of MMP-9, MMP-19, collagen type IV chains, TIMP-1 and TIMP-2 were high. MMP-2 was elevated at the protein but decreased on the cDNA level. Conclusion: Expression of basement membrane components in skeletal muscles of CLI and acute limb ischemia patients is altered, possibly contributing to the pathogenesis of peripheral arterial disease.

Combined Use of Warfarin and Aspirin Decreases Mortality in Patients with Peripheral Arterial Disease.

Anti-platelet therapy with aspirin (ASA) is standard therapy for patients with peripheral arterial disease (PAD). While ASA is not felt to impact the natural history of PAD, it decreases mortality from stroke, myocardial infarction, and other co-morbidities in the patients with PAD. Anticoagulation with warfarin (WAR) is indicated in arterial and venous thrombo-embolic conditions such as deep vein thrombosis and atrial fibrillation, but is generally considered not beneficial in patients with PAD. We retrospectively identified patients via ICD9 code who were diagnosed with PAD between January and December 2000, and assessed their course through July 2005. Of 530 individuals, 45 had a history of taking ASA and WAR concomitantly, 116 of taking WAR alone, 219 of taking ASA alone, and 150 received neither drug. Age, mortality, prevalence of hemorrhage and of co-morbid conditions (smoking, diabetes mellitus, atrial fibrillation, stroke, myocardial infarction, hypertension, coronary artery disease, hyperlipidemia, congestive heart failure, renal failure, and chronic obstructive pulmonary disease) that could affect mortality or hemorrhage were determined. Results are illustrated in the table.GroupWAR+ASAWARASANeithern=45n=116n=219n=150Mortality n (%)12 (26.7)51 (44.0)91 (41.6)71 (47.3)Hemorrhage N (%)6 (13.3)10 (8.6)6 (2.7)17 (11.3)Type of Hemorrhage3-GI8-GI6-GI13-GI2-ICH1-Nose3-ICH1-ST1-ST1-HematuriaAge*73 ± 973 ± 973 ± 972 ± 11Co-Morbid Conditions/Patient*5.4 ± 1.74.1 ± 1.63.5 ± 1.62.9 ± 1.7INR*2.2 ± 0.72.2 ± 0.5ICH= Intracranial ST= Soft Tissue * Mean ± SDThe higher number (not statistically significant) of co-morbid conditions in patients receiving WAR was because most of these individuals had atrial fibrillation. We observed a significant decrease in mortality in patients receiving WAR+ASA compared to patients on WAR alone (Chi-square, p=0.044) and neither drugs (p=0.014), and a trend for decreased mortality compared with patients on ASA alone (p=0.062). However, we observed an increased prevalence of hemorrhage in patients receiving WAR with or without ASA compared with individuals receiving ASA alone (WAR vs ASA p=0.016; WAR+ASA vs ASA p=0.002). We suspect that the frequent hemorrhagic events observed in individuals on neither drug may in part explain why these individuals were not on ASA and/or WAR. This retrospective data suggests combination therapy with WAR+ASA may be better than either agent alone or no therapy for reducing mortality in patients with PAD. Further, this data suggests that the pathogenesis of PAD may involve both platelet and non-platelet mediated hypercoagulable states.

Blood pressure changes in the leg on standing.

Normotensive and hypertensive patients develop peripheral arterial disease. The authors hypothesized that significant changes in lower extremity blood pressures occur upon standing, which could play a role in the pathogenesis of peripheral arterial disease. Forty-one subjects had blood pressure measurements performed in the arm and ankle in the supine and standing positions. The data show a marked increase in leg blood pressure on assuming the standing position, with mean increases of 65 mm Hg in systolic and 62 mm Hg in diastolic blood pressure in the lower extremities, compared with the arm on standing. In addition, the changes in diastolic pressure in the leg on standing were significantly correlated to height (r=0.47; p<0.002). These data reveal a previously unappreciated aspect of blood pressure, namely a large increase in lower extremity blood pressure values on standing, which may predispose to peripheral arterial disease.

Therapeutic Angiogenesis Induced by Human Recombinant Hepatocyte Growth Factor in Rabbit Hind Limb Ischemia Model as Cytokine Supplement Therapy

Hepatocyte growth factor (HGF) exclusively stimulates the growth of endothelial cells without replication of vascular smooth muscle cells and acts as a survival factor against endothelial cell death. Therefore we hypothesized that a decrease in local vascular HGF might be related to the pathogenesis of peripheral arterial disease. We initially evaluated vascular HGF concentration in the vessels of patients with arteriosclerosis obliterans. Consistent with in vitro findings that hypoxia downregulated vascular HGF production, vascular HGF concentration in the diseased segments of vessels from patients with arteriosclerosis obliterans was significantly decreased as compared with disease-free segments from the same patients (P<0.05), accompanied by a marked reduction in HGF mRNA. On the other hand, a novel therapeutic strategy for ischemic diseases that uses angiogenic growth factors to expedite and/or augment collateral artery development has recently been proposed. Thus in view of the decreased endogenous vascular HGF, rhHGF (500 micrograms/animal) was intra-arterially administered through the internal iliac artery of rabbits in which the femoral artery was excised to induce unilateral hind limb ischemia, to evaluate the angiogenic activity of HGF, which could potentially have a beneficial effect in hypoxia. Administration of rhHGF twice on days 10 and 12 after surgery produced significant augmentation of collateral vessel development on day 30 in the ischemic model as assessed by angiography (P<0.01). Serial angiograms revealed progressive linear extension of collateral arteries from the origin stem artery to the distal point of the reconstituted parent vessel in HGF-treated animals. In addition, we examined the feasibility of intravenous administration of rhHGF in a moderate ischemia model. Importantly, intravenous administration of rhHGF also resulted in a significant increase in angiographic score as compared with vehicle (P<0.01). Overall, a decrease in vascular HGF might be related to the pathogenesis of peripheral arterial disease. In the presence of decreased endogenous HGF, administration of rhHGF induced therapeutic angiogenesis in the rabbit ischemic hind limb model, as potential cytokine supplement therapy for peripheral arterial disease.