Validation of a Standardised Duplex Ultrasound Classification System for the Reporting and Grading of Peripheral Arterial Disease.

OBJECTIVE: Duplex ultrasound (DUS), a non-invasive means of arterial mapping, allows for the reliable diagnosis of peripheral arterial disease (PAD). One of the authors (C.P.O.), developed a standardised DUS based scoring system, devised for rapid detection and reporting of PAD. The purpose of this study was to validate this system, and to determine the diagnostic performance both overall and per disease severity. METHODS: In total, 250 participants were recruited, based on diagnosis of (n = 125) or absence of PAD (n = 125) from general practice registers. Right and left legs per subject were handled as independent readings, determining actual PAD status via ankle brachial pressure index (ABPI) < 0.9, and then further grading disease severity using suggested ABPI ranges. Data were excluded if no corresponding ABPI value was obtained per DUS determination or if the ABPI reading was > 1.4, owing to the risk of false negatives due to incompressible vessels. Diagnostic sensitivity and specificity were obtained overall, and per severity classification. Furthermore, inter-rater agreement between ABPI and DUS determined PAD severity was determined by linear weighted Cohen's kappa. RESULTS: The sensitivity and specificity in the detection of disease overall was 81.0% (95% confidence interval [CI] 73.4 - 87.2) and 86.3% (95% CI 82.3 - 89.8), respectively. From mild to severe PAD, sensitivity increased from 71.1% (95% CI 55.7 - 83.6) to 89.3% (95% CI 71.8 - 97.7). Furthermore, a Cohen's kappa value of 0.63 (95% CI 0.57 - 0.69) was obtained, indicating moderate agreement between the two diagnostic methods. CONCLUSION: The findings of this study validate the diagnostic performance of the standardised DUS scoring system, as well as its capacity to grade severity of disease, offering a potential tool for the identification of PAD in community/research settings following initial screening methods. Confirmatory work could include a comparison of DUS determined disease with gold standard methods of non-invasive angiography, and novel tools such as toe flex near infrared spectroscopy and multisite photoplethysmography.

Reliability of the Edinburgh Claudication Questionnaire for Identifying Symptomatic PAD in General Practice.

The Edinburgh Claudication Questionnaire (ECQ) was developed to help identify peripheral arterial disease (PAD) in the general population but has not been validated against diagnostic arterial imaging methods such as Duplex Vascular Ultrasound Scanning (DUS). In the present study, we assessed the accuracy of the ECQ for diagnosis using DUS. As part of a National Institute of Health Research funded project looking at novel diagnostic methods, 250 patients were studied from 15 general practices across North East England from May 2015 and November 2016. Practices identified those with a PAD diagnosis from their registers as well as age- and sex-matched controls. All the ECQs were recorded by a vascular specialist nurse. Duplex vascular ultrasound scanning was used as a reference standard for the diagnosis of occlusive PAD. The ECQ had a sensitivity of 52.5% (95% CI: 42.3%-62.5%), specificity of 87.1% (95% CI: 80.6%-92.0%), positive likelihood ratio of 4.06 (95% CI: 2.57-6.42), and negative likelihood ratio of 0.55 (95% CI: 0.44-0.68) compared with reference standard DUS. The ECQ has relatively poor overall diagnostic test accuracy in isolation. It may be helpful in ruling out PAD or as a supplementary test to improve diagnosis of symptomatic disease in General Practice.

Accuracy of Peripheral Arterial Disease Registers in UK General Practice: Case-Control Study.

BACKGROUND: Approximately 20% of the UK population aged 55 to 75 years have evidence of peripheral arterial disease (PAD). PAD affects quality of life and life expectancy if not appropriately diagnosed and managed. At risk patients require accurate diagnosis to ensure optimal treatment to slow disease progression and minimize adverse outcomes. AIM: To assess the accuracy of general practice (GP) registration of the diagnosis of peripheral arterial disease (PAD). DESIGN AND SETTING: An observational analytic case-control study. As part of a National Institute for Health Research-funded (ISRCTN13301188) project assessing novel diagnostic methods set in GP practice. METHODS: A total of 125 patients registered as having PAD and 125 age- and sex-matched controls were recruited from 15 general practices across North East England. The register was then assessed for accuracy of diagnosis. Duplex vascular ultrasound scanning (DUS) undertaken by vascular scientists was used as the gold standard reference for PAD. RESULTS: The PAD register had a sensitivity of 86% (95% CI 77%-92%) and specificity of 74% (95% CI 67%-81%) when compared with DUS. The positive predictive value, however, was 69.6% (95% CI 63%-75%) and negative predictive value 88.8% (95% CI 82%-92%). The overall diagnostic effectiveness of the PAD register was 79.2% (95% CI 73%-84%). CONCLUSION: This analysis indicates that while PAD is detected with reasonable sensitivity in primary care, many patients registered with a diagnosis of PAD lacked DUS-proven disease. Improved approaches to the objective diagnosis of PAD may improve diagnosis and management of PAD in primary care.

Color Doppler Ultrasound Imaging in the Assessment of Iliac Endofibrosis.

Endofibrosis (EF) of the iliac arteries is a flow-limiting condition typically seen in highly trained endurance athletes. Thirty-seven athletes (74 limbs) were referred to our department with suspected EF. All patients had a pre- and postexercise color Doppler ultrasound (CDU) of the iliac arteries. Doppler waveform and peak systolic velocity (PSV) and end-diastolic velocity (EDV) were assessed pre- and postexercise. Endofibrosis was diagnosed with CDU in 24 athletes (29 limbs). Arterial wall and course abnormalities were detected at rest in 20 (67%) symptomatic limbs of athletes with and 4 (22%) symptomatic limbs of athletes without EF. Postexercise abnormal waveforms of the stenotic/damped type were seen in the iliac arteries in all 29 limbs of athletes diagnosed with EF. These waveform changes were accompanied by high PSV (>350 cm/s) and EDV (>150 cm/s), with (n = 10; 34%) or without (n = 19; 66%) the evidence of reduced arterial lumen caliber. Color Doppler ultrasound can be used to detect EF.

Helping expectant mothers understand inadequate ultrasound images.

BACKGROUND: Obstetric ultrasound scans may fail to provide all the information that is needed because of poor visualisation. Two main causes of poor visualisation are addressed. These are poor foetal position and poor quality imaging due to beam distortion by overlying fatty tissue. METHOD: To improve communication with patients attending obstetric scans, a poster and leaflet were designed to explain these causes of inadequate scans. A questionnaire was used to assess the value of the poster. RESULTS: 57/66 (86%) questionnaires were completed. 52 (91%) found the information on the poster was helpful and well explained. For 8 (14%) the information changed their thoughts about the scan. CONCLUSION: Clear communication aids the expectant mothers understanding of why scans may be suboptimal. The way this is recorded in the scan results is discussed.

Reviewing the curriculum for physics and technology in postgraduate sonography courses.

Physics and technology is seen as a difficult subject by those training in medical ultrasound. The reasons for this are discussed. Who should teach the subject and what should be included are considered. Ways to approach the subject so as to make it more relevant and easier to learn are proposed and a basic syllabus is suggested in an appendix.

Weak Radial Artery Pulse: An unusual congenital cause.

We present an 11year-old boy with a weak right radial pulse, and describe the successful application of vascular ultrasound to identify the ulnar artery dominance and a thin right radial artery with below normal Doppler flow velocity that could explain the discrepancy. The implications of identifying this anomaly are discussed.

The beneficial effect of L-thyroxine on cardiovascular risk factors, endothelial function, and quality of life in subclinical hypothyroidism: randomized, crossover trial.

CONTEXT: Subclinical hypothyroidism (SCH) is defined as raised serum TSH levels with circulating thyroid hormones within the reference range. It is uncertain whether treatment of SCH with L-thyroxine improves cardiovascular (CV) risk factors and quality of life. OBJECTIVE: The objective of the study was to assess CV risk factors and patient-reported outcomes after treatment. DESIGN: This was a randomized, double-blind, crossover study of L-thyroxine and placebo. SETTING: The study was conducted with community-dwelling patients. PATIENTS: One hundred patients [mean age (sd) 53.8 (12) yr, 81 females] with SCH [mean TSH 6.6 (1.3) mIU/liter] without previously treated thyroid or vascular disease. INTERVENTION: Intervention consisted of 100 microg L-thyroxine or placebo daily for 12 wk each. MEASUREMENTS: Primary parameters were total cholesterol (TC) and endothelial function [brachial artery flow-mediated dilatation (FMD)], an early marker of atherosclerosis. Patient-reported outcomes were also assessed. RESULTS: L-thyroxine treatment reduced TC (vs. placebo) from 231.6 to 220 mg/dl, P < 0.001; low-density lipoprotein cholesterol from 142.9 to 131.3 mg/dl, P < 0.05; waist to hip ratio from 0.83 to 0.81, P < 0.006; and improved FMD from 4.2 to 5.9%, P < 0.001. Multivariate analysis showed that increased serum free T(4) level was the most significant variable predicting reduction in TC or improvement in FMD. Furthermore, the symptom of tiredness improved on L-thyroxine therapy, but other patient-reported outcomes were not significantly different after correction for multiple comparisons. CONCLUSION: SCH treated by L-thyroxine leads to a significant improvement in CV risk factors and symptoms of tiredness. The CV risk factor reduction is related to the increased level of achieved free T(4) concentration.

Thermography and colour duplex ultrasound assessments of arterio-venous fistula function in renal patients.

Vascular and clinical assessments of arterio-venous fistula (AVF) function and access are important in patients undergoing or preparing to undergo renal dialysis. Objective assessment techniques include colour duplex ultrasound and more recently medical infrared thermography. Ideally, these should help assess problems relating to fistula failure or to vascular steal from the hand which can result from excessive fistula blood flow. The clinical value of thermography, as yet, has not been assessed for this patient group. The aims of this study were therefore to investigate the relationships between thermography skin temperature measurement and (a) quantitative ultrasound measurement of AVF blood flow, and (b) qualitative clinical assessment of vascular steal from the hands. Fifteen adult patients underwent thermal imaging of the upper limbs, colour duplex ultrasound to derive AVF blood flow from brachial artery blood flow measurements, and a clinical evaluation for vascular steal. Temperature measurements were extracted from the thermograms, including bilateral arm and hand (Fistula -- Non-Fistula) differences, for comparison with derived AVF blood flow and steal grading. Derived AVF blood flow ranged from 30 to 1,950 ml min(-1), with a mean rate close to one litre per minute. Thermography detected the warmer superficial veins in proximity to the patent fistulas, with bilateral differences in fistula region skin temperature correlated with derived AVF blood flow (using maximum temperature measurements the correlation was +0.71 [p < 0.01]; and using mean temperature measurements the correlation was +0.56 [p < 0.05]). When thermography measurements were compared with the clinical assessment of steal the mean hand temperature differences separated steal from non-steal patients with an accuracy of greater than 90%. In summary, we have now demonstrated the potential clinical value of medical infrared thermography for assessing AVF function in renal patients.

Photoplethysmography detection of lower limb peripheral arterial occlusive disease: a comparison of pulse timing, amplitude and shape characteristics.

The assessment and diagnosis of lower limb peripheral arterial occlusive disease (PAOD) is important since it can lead progressively to disabling claudication, ischaemic rest pain and gangrene. Historically, the first assessment has been palpation of the peripheral pulse since it can become damped, delayed and diminished with disease. In this study we investigated the clinical value of objective photoplethysmography (PPG) pulse measurements collected simultaneously from the right and left great toes to diagnose disease in the lower limbs. In total, 63 healthy subjects and 44 patients with suspected lower limb disease were studied. Pulse wave analysis techniques extracted timing, amplitude and shape characteristics for both toes and for right-to-left toe differences. Normative ranges of pulse characteristics were then calculated for the healthy subject group. The relative diagnostic values of the different pulse features for detecting lower limb arterial disease were determined, referenced to the established ankle-brachial pressure index (ABPI) measurement. The ranges of pulse characteristics and degree of bilateral similarity in healthy subjects were established, and the degrees of pulse delay, amplitude reduction, and damping and bilateral asymmetry were quantified for different grades of disease. When pulse timing, amplitude and shape features were ranked in order of diagnostic performance, the shape index (SI) gave substantial agreement with ABPI (>90% accuracy, kappa 0.75). SI also detected higher grade disease, for legs with an ABPI less than 0.5, with a sensitivity of 100%. The simple-to-calculate timing differences between pulse peaks produced a diagnostic accuracy of 88% for all grades of arterial disease (kappa 0.70), and 93% for higher grade disease (kappa 0.77). These contrasted with the limited discriminatory value of PPG pulse amplitude. The low-cost and simplicity of this optical-based technology could offer significant benefits to healthcare, such as in primary care where non-invasive, accurate and simple-to-use (de-skilled) diagnostic techniques are desirable.