Richard B. Allan

A Comparison of Flow-mediated Dilatation and Peripheral Artery Tonometry for Measurement of Endothelial Function in Healthy Individuals and Patients with Peripheral Arterial Disease

OBJECTIVE Flow-mediated dilatation (FMD) and peripheral artery tonometry (PAT) are commonly used methods for assessing endothelial function in a research setting but it is unclear how well they correlate. This study aimed to compare and correlate these methods in patients with peripheral arterial disease (PAD) and in healthy individuals. MATERIALS AND METHODS FMD and PAT measurements were obtained as samples of convenience from 26 patients with PAD and 25 healthy subjects. FMD was defined as the percentage increase in the brachial artery diameter after distal occlusion and PAT was measured using the reactive hyperaemia index (RHI). RESULTS Patients with PAD had a significantly lower FMD than healthy subjects (2.43% vs. 5.80%, p < 0.001). No difference was found in RHI between the two groups. No correlation was found between the FMD and RHI in subjects with PAD (r = 0.284, p = 0.160), in healthy subjects (r = 0.153, p = 0.464) or when both groups were combined (r = 0.174, p = 0.22). CONCLUSION The lack of change in RHI in PAD patients suggests that PAT is not a sensitive measure of endothelial function. The lack of correlation suggests that FMD and PAT are not interchangeable. PAT should not be used as a substitute for FMD as a measure of endothelial function.

Validation of a Brief Dietary Assessment Tool for Estimating Dietary EPA and DHA Intake in Australian Adults at Risk of Cardiovascular Disease.

Background: Short food frequency questionnaires (FFQs) are powerful screening instruments for estimating nutrient intakes and play an important role in risk stratification in vulnerable populations. Omega-3 fatty acids are of increasing importance in the prevention of chronic and degenerative disease, especially in older adults who are at higher risk of these chronic conditions. A short FFQ exists to rapidly assess omega-3 intake from marine sources, however it has not previously been validated for agreement with total omega-3 intake and ability to identify suboptimal omega-3 intakes in older adults or for use in Australia. Objective: The aim of the study was to validate a 9-item marine omega-3 FFQ (MFQ) for assessment of omega-3 intake against a validated 74-item semiquantitative FFQ. Methods: One hundred and eight participants (mean age 67 ± 10 years, 47% male) completed the MFQ designed to estimate omega-3 intake from marine sources and the 74-item FFQ designed to estimate usual omega-3 and total energy intake in addition to other nutrients. To test agreement between the two questionnaires for estimating total omega-3 intake, mean bias and 95% limits of agreement (LOA) were calculated. Sensitivity and specificity were assessed using 2 × 2 contingency tables based on whether participants did or did not meet National Heart Foundation (NHF) recommendations for omega-3 intake per day. Results: Mean intake of omega-3 estimated from the MFQ was 210 ± 235 mg/day compared with 295 ± 260 mg/day as estimated by the FFQ. Mean bias (95% LOA) for omega-3 assessed by the two questionnaires was 89 mg/day (−475 mg to 653 mg). The MFQ achieved 98% sensitivity and 31% specificity for the omega-3 cut-off of 500 mg/day. When nutrient composition of the marine products were replaced with Australian data, mean intake of omega-3 was 230 ± 253 mg and the mean bias improved to 64 mg (−681 mg to 553 mg) and achieved 93% sensitivity and 40% specificity. Conclusions: The MFQ shows promise as a rapid screening tool for identifying older adults with intakes of omega-3 fatty acids likely to be below recommendations for chronic and degenerative disease risk reduction. Given the clinically meaningful mean bias and wide LOA, it cannot be recommended as an appropriate tool for the purpose of reporting average intake of individuals. Use of Australian nutrient data improved the mean bias of the tool in estimating total omega-3 intake. The values should be replaced and the MFQ could then be a useful tool for research purposes at the population level.

Precise mid-trimester placenta localisation: does it predict adverse outcomes?

A low‐lying placenta detected at the mid‐pregnancy ultrasound is commonly reported to warn against potential morbidity associated with placenta praevia. There is no information on what distance away from the internal cervical os is safe.

A Comparison of Measures of Endothelial Function in Patients with Peripheral Arterial Disease and Age and Gender Matched Controls

This study compared flow-mediated dilatation (FMD), peripheral artery tonometry (PAT), and serum nitric oxide (NO) measures of endothelial function in patients with peripheral artery disease (PAD) against age/gender matched controls. 25 patients (mean age: 72.4 years, M : F 18 : 7) with established PAD and an age/gender matched group of 25 healthy controls (mean age: 72.4 years, M : F 18 : 7) were studied. Endothelial function was measured using the % FMD, reactive hyperemia index (RHI) using PAT and serum NO (μmol). Difference for each method between PAD and control patients and correlation between the methods were investigated. FMD and RHI were lower in patients with PAD (median FMD for PAD = 2.16% versus control = 3.77%, p = 0.034 and median RHI in PAD = 1.64 versus control = 1.92, p = 0.005). NO levels were not significantly different between the groups (PAD median = 7.70 μmol, control median = 13.05 μmol, p = 0.662). These results were obtained in elderly patients and cannot be extrapolated to younger individuals. FMD and PAT both demonstrated a lower hyperaemic response in patients with PAD; however, FMD results in PAD patients were unequivocally reduced whereas half the PAD patients had RHI values above the established threshold for endothelial dysfunction. This suggests that FMD is a more appropriate method for the measurement of NO-mediated endothelial function.

The impact of abdominal aortic aneurysm on muscle mass and energy expenditure: A novel preliminary investigation.

Objective Vascular surgical patients, including those with abdominal aortic aneurysm (AAA), are nutritionally vulnerable. The aim of this study was to compare resting energy expenditure (REE) of patients with AAA relative to age- and gender-matched controls and explore relationships between aneurysm size and muscle mass. Methods Twenty patients with AAA underwent assessment of REE using indirect calorimetry. Mid-arm circumference and triceps skinfold thickness were measured and corrected arm muscle area calculated. Twenty gender- and age-matched controls were assessed using the same procedures. Results Mean (SD) age of participants with AAA was 74.7 (7.7) years, size of AAA ranged from 45 to 70 mm. Median (IQR) REE was significantly higher than controls [5990 (5469, 7017) kJ/day versus 5086 (4536, 5886) kJ/day, p = .011; or 69 (64, 80) kJ/kg/day versus 66 (61, 69) kJ/kg/day, p = .046]. While weight-adjusted REE was independent of aneurysm size (r = .200; p = .397), as aneurysm size increased, weight-adjusted corrected arm muscle area decreased (r = −.576; p = .008). Conclusion The raised REE and decline in muscle mass associated with larger AAA suggest that early detection and attention to nutritional requirements of patients with AAA may be warranted.

The impact of different supervised exercise regimens on endothelial function in patients with intermittent claudication

Background and objectives The impact of supervised exercise training on endothelial function in patients with intermittent claudication is unclear. This study assesses the impact of treadmill-based supervised exercise training alone or in combination with resistance training on pain free walking distance, flow-mediated dilatation, reactive hyperaemia index, nitric oxide and asymmetric dimethylarginine. Methods Thirty-five patients with intermittent claudication were randomised to 12 weeks of treadmill-only supervised exercise training (Group 1) or a combination of treadmill and lower-limb resistance supervised exercise training (Group 2). Pain free walking distance was assessed by six-minute walk test. Endothelial function was assessed by brachial artery flow-mediated dilatation, reactive hyperaemia index and serum analysis of asymmetric dimethylarginine and nitric oxide. Results Pain free walking distance improved within Group 1 (160 m to 204 m, p = 0.03) but not Group 2 (181 m to 188 m, p = 0.82), no between group difference. No significant change in flow-mediated dilatation or reactive hyperaemia index in either group. Nitric oxide decreased in Group 1 (15.0 µmol/L to 8.3 µmol/L, p = 0.003) but not Group 2 (11.2 µmol/L to 9.1 µmol/L, p = 0.14), p = 0.07 between groups. Asymmetric dimethylarginine decreased in Group 2 (0.61 µmol/L to 0.56 µmol/L, p = 0.03) but not Group 1 (0.58 µmol/l to 0.58 µmol/L, p = 0.776), no between group difference. Conclusion Supervised exercise training does not improve endothelial function as measured by flow-mediated dilatation, reactive hyperaemia index and nitric oxide bioavailability.

Can fish oil supplementation improve endothelial function in asymptomatic offspring of patients with peripheral arterial disease

Correspondence: J Ian Spark Department of Vascular Surgery, Flinders Medical Centre, Flinders Drive, Bedford Park, Adelaide, SA 5042, Australia Tel +618 8204 5445 Fax +618 8204 7106 Email ian.spark@health.sa.gov.au Background: Peripheral arterial disease affects 10%–25% of adults aged .55 years, and while a multitude of risk factors exist, one key influence is genetics. Rather than awaiting the onset of debilitating symptoms, interventions that target high-risk individuals and prevent or delay the onset of symptoms would have widespread impact. The aim of this study is to implement a 12-week fish oil intervention (10 mL/day containing approximately 1.5 g of eicosapentaenoic acid and 1 g of docosahexaenoic acid), with the intention of improving endothelial function, inflammation, and lipid status in a high-risk population, ie, those with impaired endothelial function and a parent with symptomatic peripheral arterial disease. Methods: This is a parallel-group, double-blind, randomized controlled trial involving administration of fish oil containing either about 1.5 g of docosahexaenoic acid and 1 g of docosahexaenoic acid (intervention) or about 0.15 g of eicosapentaenoic acid and about 0.1 g of docosahexaenoic acid for 12 consecutive weeks (control). The participants are 100 offspring of adults with diagnosed peripheral arterial disease who themselves have an ankle-brachial pressure index

Accuracy of ultrasound to identify chronic liver disease.

0.9 but impaired endothelial function according to peripheral arterial tonometry. Measures performed at baseline and at 6 and 12 weeks include flow-mediated dilatation, Creactive protein, absolute neutrophil and lymphocyte counts, tumor necrosis factor-α, interleukin-1β, and interleukin-6 levels, thromboxane and prostacyclin, lipid status, and homocysteine, nitrite, and nitrate levels. Participants will be phoned fortnightly to monitor adherence and side effects, while participants will maintain a diary of fish oil consumption on a daily basis, and fish oil returned will be measured to confirm adherence. Participants will complete validated surveys to determine background diet and physical activity levels. Discussion: This study will examine the effectiveness of a moderate-dose fish oil intervention in reversing endothelial dysfunction in asymptomatic offspring of patients with peripheral arterial disease. It provides the opportunity to delay the progression of peripheral arterial disease using a cheap and readily available dietary supplement that has minimal side effects compared with synthetic vasoactive pharmacological medications.