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Background: Peripheral arterial disease (PAD) in the presence of a normal ankle-brachial index (ABI) can be diagnosed noninvasively by measuring a postexercise ABI or by measuring the toe-brachial index (TBI). Methods: This was a prospective comparative study. Over a period of 30 months, a total of 415 patients who were referred with the suspicion of vascular claudication and resting values of 0.91 ≤ ABI1.10 (P ≤ 0.022 for both), but there were no statistically significant differences found in other ABI intervals (P > 0.200 for all). Conclusions: The magnitude of the TBI reduction correlates with an increased probability of an abnormal postexercise ABI. However, this is due in part to limbs with a low TBI having a lower resting ABI on average than limbs with a normal TBI, which also correlates with the probability of an abnormal exercise test result. This study shows that the TBI and the postexercise ABI are not interchangeable for establishing a PAD diagnosis.

Objective: In patients with peripheral arterial disease (PAD), measurements of distal blood pressure form the basis of assessing the severity of the disease along with symptoms and objective findings. The reliability and accuracy of a fully automated bedside device (SysToe) vs. strain gauge plethysmography (SGP) in patients with low toe pressures in a bedside setting in an outpatient clinic of vascular surgery were investigated. Methods: This was a prospective, single blinded study carried out in compliance with the Standards of Reporting of Diagnostic Accuracy Studies. A total of 94 outpatients with symptomatic PAD in an outpatient vascular surgery clinic were included and had index measurements performed with the automated bedside device in a bedside setting by observers with no training in routine distal pressure measurements. SGP reference measurements were performed in a vascular laboratory. Results: There was agreement between modalities regarding the diagnostic classification of chronic limb threatening ischaemia (CLTI) in 79/94 (84%) patients. For detection of CLTI, Cohen's kappa was 0.57 with a sensitivity of 94%, specificity of 82%, positive predictive value (PPV) 52%, and negative predictive value (NPV) 98%. On average, the automated bedside device underestimated the pressures, compared with the SGP. The mean difference between SGP and SysToe was 9 ± 16 mmHg for right limbs and 10 ± 16 mmHg for left limbs (p < .001). Conclusion: The automated bedside device showed a high sensitivity and a high NPV for excluding CLTI. However, the low PPV may result in overdiagnosis. The automated bedside device may function as a screening tool identifying patients in need of further diagnostics with more accurate equipment, for example SGP.

AIM: To examine the interchangeability of two methods for distal pressure measurement based on photoplethysmography using a truncated or full display of the arterial inflow curve, respectively.METHODS: Toe and ankle pressures were obtained from 69 patients suspected of peripheral arterial disease (PAD). Observer reproducibility of the curve readings was examined by blinded reassessment of the pressure curves in a randomly selected subgroup (60 limbs).RESULTS: There were no significant differences in mean pressures between the two methods (p for all > .455). The limits of agreement for the differences were -15.0-15.4 mmHg for right toe pressures, -16.3-16.2 mmHg for left toe pressures, -14.2-15.7 mmHg for right ankle pressures, and -18.3-17.7 mmHg for left ankle pressures. Correlation analysis revealed intraclass correlation coefficients ≥0.960 for all measuring sites. Cohen's Kappa showed excellent agreement in diagnostic classification, with κ = 0.930 for the diagnosis of PAD and perfect agreement in the diagnosis of critical limb ischemia (κ = 1.000). The analysis of intra-observer variation for curve reading showed limits of agreement of -3.9-4.0 for toe pressures and -7.6-7.7 for ankle pressures for the method involving truncated display and -3.1-3.2 for toe pressures and -6.3-8.6 for ankle pressures for the method involving full display of the signal.CONCLUSION: The present study shows minimal differences in diagnostic classification, as well as in ankle and toe pressures, between the full display and the truncated display of the photoplethysmographic pulse signal. Furthermore, the inter-observer variation was low for both of the photoplethysmographic methods investigated.

Mercury-in-silastic strain gauge pletysmography (SGP) is a well-established technique for blood flow and blood pressure measurements. The aim of this study was to examine (i) the possible influence of clinical clues, e.g. the presence of wounds and color changes during blood pressure measurements, and (ii) intra- and inter-observer variation of curve interpretation for segmental blood pressure measurements.A total of 204 patients with known or suspected peripheral arterial disease (PAD) were included in a diagnostic accuracy trial. Toe and ankle pressures were measured in both limbs, and primary observers analyzed a total of 804 pressure curve sets. The SGP curves were later reanalyzed separately by two observers blinded to clinical clues. Intra- and inter-observer agreement was quantified using Cohen's kappa and reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland-Altman analysis.There was an overall agreement regarding patient diagnostic classification (PAD/not PAD) in 202/204 (99.0%) for intra-observer (κ = 0.969, p0.001), and 201/204 (98.5%) for inter-observer readings (κ = 0.953, p0.001). Reliability analysis showed excellent correlation between blinded versus non-blinded and inter-observer readings for determination of absolute segmental pressures (all intraclass correlation coefficients ≥ 0.984). The coefficient of variance for determination of absolute segmental blood pressure ranged from 2.9-3.4% for blinded/non-blinded data and from 3.8-5.0% for inter-observer data.This study shows a low inter-observer variation among experienced laboratory technicians for reading strain gauge curves. The low variation between blinded/non-blinded readings indicates that SGP measurements are minimally biased by clinical clues.

ObjectiveTo assess the accuracy of a fully automated portable device (APD) for diagnosing peripheral arterial disease (PAD) by measuring the toe–brachial index (TBI) and using mercury-in-silastic, strain-gauge plethysmography (SGP) as reference.DesignProspective, randomised, double-blinded diagnostic accuracy study.Materials and methodsA total of 204 consecutive patients with known or suspected PAD were randomly assigned to measurement of TBI by the portable device followed by the SGP technique or the opposite sequence. Finally, ankle–brachial index (ABI) was assessed by SGP.ResultsThe APD showed a sensitivity of 98.8%, a specificity of 61.0%, a positive predictive value of 91.0% and a negative predictive value of 92.6% for detecting PAD compared to a full SGP test comprised of ABI and TBI. According to the SGP test, 35 patients (17.2%) had an ABI > 0.90 but a TBI

Objectives To assess the intra- and inter-observer variation in laser Doppler flowmetry curve reading for measurement of toe and ankle pressures. Methods A prospective single blinded diagnostic accuracy study was conducted on 200 patients with known or suspected peripheral arterial disease (PAD), with a total of 760 curve sets produced. The first curve reading for this study was performed by laboratory technologists blinded to clinical clues and previous readings at least 3 months after the primary data sampling. The pressure curves were later reassessed following another period of at least 3 months. Observer agreement in diagnostic classification according to TASC-II criteria was quantified using Cohen's kappa. Reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland–Altman analysis. Results The overall agreement in diagnostic classification (PAD/not PAD) was 173/200 (87%) for intra-observer ( κ = .858) and 175/200 (88%) for inter-observer data ( κ = .787). Reliability analysis confirmed excellent correlation for both intra- and inter-observer data (ICC all ≥.931). The coefficients of variance ranged from 2.27% to 6.44% for intra-observer and 2.39% to 8.42% for inter-observer data. Subgroup analysis showed lower observer-variation for reading of toe pressures in patients with diabetes and/or chronic kidney disease than patients not diagnosed with these conditions. Bland–Altman plots showed higher variation in toe pressure readings than ankle pressure readings. Conclusions This study shows substantial intra- and inter-observer agreement in diagnostic classification and reading of absolute pressures when using laboratory technologists as observers. The study emphasises that observer variation for curve reading is an important factor concerning the overall reproducibility of the method. Our data suggest diabetes and chronic kidney disease have an influence on toe pressure reproducibility.

BackgroundPeripheral arterial disease (PAD) can be diagnosed noninvasively by segmental blood pressure measurement and calculating an ankle-brachial index (ABI) or toe-brachial index (TBI). The ABI is known to be unreliable in patients with vascular stiffness and fails to detect the early phase of arteriosclerotic development. The toe vessels are less susceptible to vessel stiffness, which makes the TBI useful. However, the diagnostic limits used in guidelines, clinical settings, and experimental studies vary substantially. This review provides an overview of the evidence supporting the clinical use of the TBI.MethodsA review of the literature identified studies reporting the use of the TBI regarding guideline recommendations, normal populations, correlations to angiographic findings, and prognostic implications.ResultsEight studies conducted in a normal population were identified, of which only one study used imaging techniques to rule out arterial stenosis. A reference value of 0.71 was estimated as the lowest limit of normal based on the weighted average in studies with preheating of the limbs. A further seven studies showed correlations of the TBI with angiographic findings. The TBI had a sensitivity of 90% to 100% and a specificity of 65% to 100% for the detection of vessel stenosis. Few studies investigated the value of the TBI as a prognostic marker for cardiovascular mortality and morbidity, and no firm conclusions could be made. Studies have, however, shown correlation between the TBI and comorbidities such as kidney disease, diabetes, and microvasculature disease.ConclusionsIn contrast to the well-defined and evidence-based limits of the ABI, the diagnostic criteria for a pathologic TBI remain ambiguous. Although several guidelines and reviews of PAD diagnostics recommend a TBI

We examine the reliability of single and repeated blood pressure measurements at ankle, toe, and arm levels for the diagnosis of peripheral arterial disease (PAD) by laser Doppler flowmetry. Segmental pressures were measured in 200 patients with known or suspected PAD. Segmental indices were calculated using (1) one measurement [M-1], two measurements [M-2], or by a predefined reproducibility criterion (RC) as well as (2) by using one brachial blood-pressure (BBP-one) or correspondent to each segmental pressure (BBP-all) as reference. The agreement in diagnosis of PAD by Cohen's Kappa was κ = 0.930 when comparing RC to M-1, and κ = 0.977 when comparing RC to M-2. The same comparison showed excellent relative reliability for segmental indices (all intra-class correlation coefficients (ICC) ≥ 0.980). Diagnostic classification agreement for BBP-all versus BBP-one were κ = 0.831 for RC, κ = 0.804 for M-1, and κ = 0.847 for M-2. The relative reliability analysis showed excellent correlation in segmental indices (all ICC ≥ 0.957). The study shows minimal difference in segmental indices and diagnostic classification when comparing calculations based on the listed strategies. However, the study indicated that it is important to measure BBPs correspondent to each segmental pressure.

Objective Mitral valve replacement with preservation of the entire subvalvular apparatus entails superior postoperative left ventricular function compared with other techniques. However, this option is often not possible because of valve pathology. We hypothesized that preservation of only 4 mitral valve secondary ("strut") chordae would be functionally and geometrically equivalent to total valve preservation in the long-term setting. In a porcine mitral valve replacement model we investigated the long-term effects of 3 surgical techniques on left ventricular function and geometry: (1) total preservation of the native valve, (2) strut chordal preservation, and (3) total excision of the subvalvular apparatus. Methods Forty 60-kg pigs were randomized to 1 of the 3 techniques. Global and regional left ventricular function and dimensions were assessed with cardiovascular magnetic resonance and conductance catheter 90 days after mitral valve replacement. Groups were compared by multivariate analysis of variance. Results There was no overall difference between groups 1 and 2. Group 3 animals had (1) greater base-apex diastolic and systolic lengths, and smaller short-axis diameters, and (2) lower sphericity indices, and greater base-apex and short-axis fractional shortening than groups 1 and 2. Regional analysis showed slimming and elongation to occur primarily in the basal left ventricular segments. Left ventricular contractility and hemodynamic parameters did not differ between groups. Conclusions Strut chordal preservation was equivalent to total valve preservation during mitral valve replacement, whereas total chordal resection caused significant left ventricular slimming with compensatory increases in fractional shortening. Therefore, to preserve left ventricular geometry, special attention must be paid to maintain the valvular–ventricular continuity through the strut chordae during mitral valve replacement. This concept may have important therapeutic implications for chordal-sparing mitral valve replacement.

ObjectiveTo assess the diagnostic accuracy of laser Doppler flowmetry (LDF) with mercury-in-silastic strain gauge plethysmography (SGP) as a reference test for measuring the toe and ankle pressures in patients with known or suspected peripheral arterial disease (PAD).MethodsThis was a prospective, randomized, blinded diagnostic accuracy study. Toe and ankle pressures were measured using both methods in 200 consecutive patients, who were recruited at our vascular laboratory over a period of 30 working days. Classification of PAD and critical limb ischemia (CLI) was made in accordance with TASC-II criteria.ResultsThe LDF method demonstrated 5.8 mm Hg higher mean toe pressures than the SGP method for the right limb and 7.0 mm Hg for the left limb (both P < .001). There were no significant differences in the mean ankle pressures (both P > .129). The limits of agreement for the differences (SGP − LDF) were −31.7 to 20.2 mm Hg for right toe pressures, −28.0 to 14.0 mm Hg for left toe pressures, −25.5 to 22.8 mm Hg for right ankle pressures, and −26.9 to 24.6 mm Hg for left ankle pressures. A correlation analysis of the absolute pressures using the two methods showed an intraclass correlation coefficient of 0.902 (95% confidence interval [CI], 0.835-0.938) for right toe pressures, 0.919 (95% CI, 0.782-0.960) for the left toe pressures, 0.953 (95% CI, 0.937-0.965) for right ankle pressures, and 0.952 (95% CI, 0.936-0.964) for left ankle pressures. Cohen's Kappa showed an agreement in the diagnostic classification of κ = 0.775 (95% CI, 0.631-0.919) for PAD and κ = 0.780 (95% CI, 0.624-0.936) for CLI.ConclusionsLDF showed a good correlation with SGP over a wide range of toe and ankle pressures, as well as substantial agreement for the diagnostic classification of PAD including CLI.