Understanding Patient Acceptance of Risk with Treatment Options for Intermittent Claudication.

BACKGROUND: Intermittent claudication has a major impact on the quality of life and functional ability of the patient. However, when treating these patients, management is largely influenced by vascular surgeons' perceptions of risk. There is little information available regarding the level of risk that patients perceive to be acceptable, when considering complications of treatment. This study investigates patients' acceptance of risk associated with current management options for intermittent claudication and explores factors associated with greater risk acceptance. METHODS: Patients with confirmed intermittent claudication presenting to vascular clinic and supervised exercise classes were surveyed in a single-center prospective study. A standard gamble-type method was used to measure patients' acceptance of risk associated with medical treatment, angioplasty, and surgical bypass. Level of risk acceptance was correlated to patient factors. RESULTS: Fifty patients were surveyed; 74% were male, median age was 68 years (interquartile range [IQR] 59-74), maximal walking distance was 100 m (IQR 70-200), and ankle-brachial pressure index was 0.65 (IQR 0.60-0.78). Median risk acceptance for treatment failure was 70% for medical treatment, 50% for angioplasty, and 40% for surgical bypass. Median risk acceptance for major amputation and death was 0% for all 3 management options. Claudicants with maximal walking distance <100 m accepted higher risk of treatment failure (P = 0.0005 for medical treatment, P = 0.0038 for angioplasty), and death with medical treatment (P = 0.0009). There was no significance between claudication distance and risk acceptance of major amputation with any treatment modality or death with angioplasty or surgical bypass. There was no significant correlation among level of risk acceptance and age, gender, or diabetic status. CONCLUSIONS: Claudicants are prepared to accept significant risk of treatment failure, in order to gain benefit, but regardless of claudication distance, patients have low acceptance of the risk of amputation or death. Patient acceptance of risk should be considered when planning management.

A prospective, multi-centre, randomised, open label, parallel, comparative study to evaluate effects of AQUACEL® Ag and Urgotul® Silver dressing on healing of chronic venous leg ulcers.

This study compared wound healing efficacy of two silver dressings, AQUACEL(®) Ag and Urgotul(®) Silver, against venous ulcers at risk of infection, over 8 weeks of treatment. The primary objective was to show non inferiority of AQUACEL(®) Ag to Urgotul(®) Silver. Patients (281) were randomised into two groups. The AQUACEL(®) Ag group had 145 patients treated with AQUACEL(®) Ag for 4 weeks followed by AQUACEL for another 4 weeks. TheUrgotul(®) Silver group had 136 patients treated with Urgotul(®) Silver for 4 weeks followed by Urgotul(®) for another 4 weeks. In both groups, ulcer size and depth, safety events and ulcer healing were compared. After 8 weeks of treatment, the AQUACEL(®) Ag group had a relative wound size reduction (49·65% ± 52·53%) compared with the Urgotul(®) Silver group (42·81% ± 60·0%). The non inferiority of the AQUACEL(®) Ag group to the Urgotul(®) Silver group was established based on the difference between them (6·84% ± 56·3%, 95% confidence interval -6·56 to 20·2) and the pre-defined non inferiority margin (-15%). Composite wound healing analysis showed that the AQUACEL(®) Ag group had statistically higher percentage of subjects with better wound progression (66·9% versus 51·9%, P = 0·0108). In general, both dressings were effective at promoting healing of venous ulcers.

High risk of peripheral arterial disease in the United Kingdom: 2-year results of a prospective registry.

We report a prospective 2-year, multicenter study of patients presenting with intermittent claudication (IC; ankle brachial blood pressure index, ABPI ≤ 0.9). Mean age of the 473 patients enrolled was 68 years, 20% were diabetics, 30% had prior symptomatic coronary heart disease (CHD), 7% had prior stroke, and 39% were current smokers. At baseline, 26.2% of patients had BP ≤ 140/85 mm Hg or lower and at 2 years this figure was 32.5% (P = .01). Current smokers had fallen to 27% (from 39%) at 2 years (P < .001). Use of antiplatelet agents, statins, and angiotensin converting enzyme inhibitors increased significantly during the course of the study as did claudication distance. Death and the composite of death, stroke or myocardial infarction (MI), occurred in 8.4% and 11.6% of patients, respectively. Prognosis was worse in patients with prior history of CHD, older age, those with diabetes and a lower ABPI.

Red blood cell migration in microvessels.

Red blood cell (RBC) migration effects and RBC-plasma interactions occurring in microvessel blood flow have been investigated numerically using a shear-induced particle migration model. The mathematical model is based on the momentum and continuity equations for the suspension flow and a constitutive equation accounting for the effects of shear-induced RBC migration in concentrated suspensions. The model couples a non-Newtonian stress/shear rate relationship with a shear-induced migration model of the suspended particles in which the viscosity is dependent on the haematocrit and the shear rate (Quemada model). The focus of this paper is on the determination of the two phenomenological parameters, Kc and Kmu, in a diffusive flux model when using the non-Newtonian Quemada model and assuming deformable particles. Previous use of the diffusive flux model has assumed constant values for the diffusion coefficients which serve as tuning parameters in the phenomenological equation. Here, previous data [Biophys. J. 92 (2007), 1858-1877; J. Fluid Mech. 557 (2006), 297-306] is used to develop a new model in which the diffusion coefficients depend upon the tube haematocrit and the dimensionless vessel radius for initially uniform suspensions. This model is validated through previous publications and close agreement is obtained.

Hsp70 expression in monocytes from patients with peripheral arterial disease and healthy controls: monocyte Hsp70 in PAD.

BACKGROUND: Heat shock proteins (HSP) are induced during cellular stress. Their role is to chaperone cellular proteins giving protection from denaturation and ultimately preventing cell death. Monocytes are key cells involved in atherosclerosis and are highly responsive to HSP induction. Therefore, we wished to examine monocyte Hsp70 expression and induction in patients with peripheral arterial disease (PAD) and in healthy controls. METHODS: We measured cellular Hsp70 levels in freshly isolated monocytes and released Hsp70 levels in plasma and monocyte culture supernatants, obtained from patients with PAD and from healthy controls. We assessed the effect of statin therapy on Hsp70 levels and examined monocyte cell survival in culture with and without immunological stress. RESULTS: Monocyte cellular Hsp70 was lower in patients with PAD compared to healthy controls (11.3 +/- 7.4 ng/10(6) cells vs 20.7 +/- 16.0 ng/10(6) cells; p < 0.001). Individuals on statin therapy from both PAD and control groups had lower monocyte Hsp70 compared to those not treated with statins. Concentrations of Hsp70 released into culture supernatants were not dependent on PAD or statin therapy. Cell survival was inversely associated with Hsp70 concentrations in culture supernatants but had no association with cellular concentrations of Hsp70. CONCLUSIONS: Cellular Hsp70 and released Hsp70 may play different roles in monocyte health. Whilst induced Hsp70 destined for release appears to be unaffected in PAD, mechanisms responsible for cellular retention of Hsp70 may provide an area for future therapeutic targets in vascular disease.

Polymorphisms in the CD36 gene modulate the ability of fish oil supplements to lower fasting plasma triacyl glycerol and raise HDL cholesterol concentrations in healthy middle-aged men.

Five SNPs in the CD36 gene, 25444G>A, 27645del>ins, 30294G>C, -31118G>A and -33137A>G in haplotypic combinations, link to fasting plasma NEFA concentrations. Fish oil lowers TAG concentrations. The influence of CD36 SNPs on hypotriglyceridemic effects is unknown. The study examines how four of the SNPs modify the effects of fish oil on fasting plasma TAG, NEFA, glucose LDL and HDL cholesterol concentrations in 111 healthy, middle-aged, Caucasian men. Subjects consumed habitual diets while taking 6g MaxEPA daily for 12 weeks. TAG decreased from 1.48 mol/l to 0.11 mmol/l, and glucose and HDL rose from 5.92 to 0.15 mmol/l and from 1.27 to 0.04 mmol/l, respectively, irrespective of genotype. NEFA was unaffected. Significant falls in TAG only occurred in individuals with the GG variant of the 25444, 30294, -31118 or -33137 SNPs. The TAG-lowering effects may be via stimulation of CD36 activity in extrahepatic tissue in individuals with the GG variants of these SNPs.

Dietary supplementation with fish oil modifies the ability of human monocytes to induce an inflammatory response.

Monocytes/macrophages are key orchestrators of inflammation and are involved in the pathogenesis of chronic inflammatory disorders, including atherosclerosis. (n-3) Fatty acids, found in fish oil, have been shown to have protective effects in such disorders. To investigate possible modes of action, we used a monocyte:endothelial cell (EC) coculture model to investigate the pro-inflammatory potential of monocytes. Monocytes were isolated from the blood of donors with peripheral arterial disease (PAD) or control donors, before and after a 12-wk supplementation of their diet with fish oil. The monocytes were cultured with human umbilical vein EC (HUVEC) for 24 h, after which the ability of the HUVEC to recruit flowing neutrophils was tested. Monocytes from either group of donors stimulated the EC to support the adhesion and migration of neutrophils. Fish oil supplementation reduced the potency of monocytes from normal subjects, but not those from patients with PAD, to induce recruitment. Concurrent medication may have acted as a complicating factor. On subgroup analysis, only those free of medication showed a significant effect of fish oil. Responses before or after supplementation were not closely linked to patterns of secretion of cytokines by cultured monocytes, tested in parallel monocultures. These results suggest that fish oil can modulate the ability of monocytes to stimulate EC and that this might contribute to their protective effects against chronic inflammatory disorders. Benefits, however, may depend on existing medical status and on other treatments being received.

Fish oil induced increase in walking distance, but not ankle brachial pressure index, in peripheral arterial disease is dependent on both body mass index and inflammatory genotype.

Peripheral arterial disease (PAD) is an atherosclerotic disease. Evidence suggests that atherosclerosis is an inflammatory condition and long chain n-3 fatty acids, found in oily fish and fish oils, have been shown to reduce inflammation. Genetic and lifestyle factors such as body mass index (BMI) also influence inflammation. In this study we have examined the effect of fish oil in patients with claudication secondary to PAD. Fish oil supplementation, providing 1g EPA and 0.7 g DHA per day for 12 weeks, increased walking distance on a treadmill set at 3.2 km/h with a 7% incline. Walking distance to first pain increased from 76.2+/-8.5 m before fish oil to 140.6+/-25.5 m after fish oil (mean+/-SEM, p=0.004) and total distance walked increased from 160.0+/-21.5 m before fish oil to 242.1+/-34.5 m after fish oil (p=0.002). Fish oil supplementation also improved ankle brachial pressure index (ABPI) from 0.599+/-0.017 before fish oil to 0.776+/-0.030 after fish oil (p<0.001). The increase in walking distance was dependent on both BMI and genotype for single nucleotide polymorphisms in the genes encoding the pro-inflammatory cytokines tumour necrosis factor-alpha and interleukin (IL)-1beta and the anti-inflammatory cytokine IL-10 (detected using amplification refractory mutation system polymerase chain reaction). Neither BMI nor any of the genotypes examined affected the ability of fish oil to increase ABPI. The mechanisms by which fish oil affects walking distance and ABPI do not appear to be the same.

Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial.

BACKGROUND: N-3 polyunsaturated fatty acids (PUFAs) from oily fish protect against death from cardiovascular disease. We aimed to assess the hypothesis that incorporation of n-3 and n-6 PUFAs into advanced atherosclerotic plaques increases and decreases plaque stability, respectively. METHODS: We did a randomised controlled trial of patients awaiting carotid endarterectomy. We randomly allocated patients control, sunflower oil (n-6), or fish-oil (n-3) capsules until surgery. Primary outcome was plaque morphology indicative of stability or instability, and outcome measures were concentrations of EPA, DHA, and linoleic acid in carotid plaques; plaque morphology; and presence of macrophages in plaques. Analysis was per protocol. FINDINGS: 188 patients were enrolled and randomised; 18 withdrew and eight were excluded. Duration of oil treatment was 7-189 days (median 42) and did not differ between groups. The proportions of EPA and DHA were higher in carotid plaque fractions in patients receiving fish oil compared with those receiving control (absolute difference 0.5 [95% CI 0.3-0.7], 0.4 [0.1-0.6], and 0.2 [0.1-0.4] g/100 g total fatty acids for EPA; and 0.3 [0.0-0.8], 0.4 [0.1-0.7], and 0.3 [0.1-0.6] g/100 g total fatty acids for DHA; in plaque phospholipids, cholesteryl esters, and triacylglycerols, respectively). Sunflower oil had little effect on the fatty acid composition of lipid fractions. Fewer plaques from patients being treated with fish oil had thin fibrous caps and signs of inflammation and more plaques had thick fibrous caps and no signs of inflammation, compared with plaques in patients in the control and sunflower oil groups (odds ratio 0.52 [95% CI 0.24-0.89] and 1.19 [1.02-1.57] vs control; 0.49 [0.23-0.90] and 1.16 [1.01-1.53] vs sunflower oil). The number of macrophages in plaques from patients receiving fish oil was lower than in the other two groups. Carotid plaque morphology and infiltration by macrophages did not differ between control and sunflower oil groups. INTERPRETATION: Atherosclerotic plaques readily incorporate n-3 PUFAs from fish-oil supplementation, inducing changes that can enhance stability of atherosclerotic plaques. By contrast, increased consumption of n-6 PUFAs does not affect carotid plaque fatty-acid composition or stability over the time course studied here. Stability of plaques could explain reductions in non-fatal and fatal cardiovascular events associated with increased n-3 PUFA intake.

Some effects of sustained compression on ulcerated tissues.

Sustained leg compression is the first line of treatment for patients with chronic venous ulcers. The success rates of this treatment vary, and the mode(s) of action are not well understood. In this study, tissue oxygen tension (TcPO2), surface pH, and reactive hyperemia measurements were made to observe changes associated with sustained compression in patients with chronic venous ulcers. Patients with chronic venous ulcers (n = 20, 13 F, 7 M, median age 65.5 years, median ulcer size 13.9 cm2) were assigned to the same treatment, wound dressings, and 4-layer bandaging during a 24-week period. Duplex ultrasound, venous refilling time, skin tissue oxygen, and ulcer surface pH were measured at defined time points. Ulcer areas were calculated from contour traces done at regular dressing changes. The difference between ulcer surface pH and control values measured proximally on the same leg diminished with healing (p = 0.02), which occurred despite the evidence of deep venous reflux. Ulcers with smaller initial areas healed quicker (p = 0.003). A greater likelihood of healing was observed in women (p = 0.017). Sustained compression may potentiate healing by acting on the microcirculation in ulcerated tissues.