Reliability of Ultrasound Diameter Measurements in Patients with a Small Asymptomatic Popliteal Artery Aneurysm: An Intra- and Inter-observer Agreement Study.

BACKGROUND: In this study the intra- and inter-observer variability of ultrasound measurements of the diameter of the popliteal artery were tested in a group of patients under surveillance for a small (diameter 10-20 mm), asymptomatic popliteal artery aneurysm (PAA). METHODS: From a group of patients under ultrasound surveillance for bilateral, asymptomatic PAAs, 13 consecutive patients agreed to participate in the study and provided informed consent. The maximum diameter of the popliteal arteries was assessed by a vascular technologist. The same assessment was repeated by a second vascular technologist, unaware of the results of the first measurement. After a week, this protocol was repeated. The intra- and inter-observer reliability of this measurement was calculated using intra-class correlation coefficients (ICCs) and Bland and Altman plots. RESULTS: Of the 10 patients with bilateral and three patients with unilateral PAA, 12 completed the 2 week protocol. A total of 86 measurements were analyzed. The mean diameter of the popliteal arteries was 13.5 ± 3.4 mm. The ICC for the intra-observer reliability of observer 1 was 0.96 (95% CI 0.92-0.99), p < .001 and of observer 2 was 0.98 (95% CI 0.95-0.99), p < .001. The ICC for the inter-observer reliability for the first measurements was 0.96 (95% CI 0.90-0.98), p < .001 and for the second measurements 0.97 (95% CI 0.94-0.99), p < .001. The Bland-Altman plots showed random error, while 95% of the variation was between 0.016 and 0.16, p > .47. The absolute magnitude of the systematic error of both observers was less than 0.135 mm (median 0.00). CONCLUSION: Ultrasound measurement of the maximum diameter of the popliteal artery is reproducible; hence, it is suitable for making a clinical treatment decision. Its use for surveillance of small, asymptomatic PAAs is justified.

Predictors of the post-thrombotic syndrome with non-invasive venous examinations in patients 6 weeks after a first episode of deep vein thrombosis.

BACKGROUND: Post-thrombotic syndrome (PTS) is a chronic complication of deep vein thrombosis (DVT) affecting a large number of patients. Because of its potential debilitating effects, identification of patients at high risk for the development of this syndrome is relevant, and only a few predictors are known. OBJECTIVES: To assess the incidence and potential predictors of PTS. METHODS: We prospectively followed 111 consecutive patients for 2 years after a first episode of objectively documented DVT of the leg. With non-invasive venous examinations, residual thrombosis, valvular reflux, calf muscle pump function and venous outflow resistance were assessed at 6 weeks, 3 months, 6 months, 1 year, and 2 years. The Clinical, Etiologic, Anatomic, and Pathophysiologi classification was used to record the occurrence and severity of PTS. Regression analysis with area under the receiver operating characteristic (ROC) curve was performed to identify potential predictors. RESULTS: The cumulative incidence of PTS was 46% after 3 months, and the incidence and severity did not increase further. Men appeared to be at increased risk as compared with women (risk ratio [RR] 1.4, 95% confidence interval [CI] 0.9-2.2), as were patients over 50 years as compared with younger patients (RR 1.4%, 95% CI 0.9-2.1). Patients with thrombosis localized in the proximal veins at diagnosis had an increased risk of PTS as compared with patients with distal thrombosis (RR 2.3%, 95% CI 1.0-5.6). PTS developed in 32 of 52 patients (62%) with residual thrombosis in the proximal veins 6 weeks after diagnosis, as compared with 17 of 45 patients (38%) without residual proximal thrombosis, leading to a 1.6-fold increased risk (95% CI 1.0-2.5). The presence of valvular reflux in the superficial veins was also a predictor at 6 weeks, with a 1.6-fold increased risk as compared with patients without superficial reflux (95% CI 1.1-2.3). A multivariate analysis of these predictors yielded an area under the ROC curve of 0.72 (95% CI 0.62-0.82). CONCLUSIONS: PTS develops in half of all patients within 3 months, with no further increase being seen up to 2 years of follow-up. Male sex, age over 50 years, proximal localization of the thrombus at entry, residual proximal thrombosis and superficial valvular reflux at 6 weeks seem to be the most important predictors of PTS in patients with a first episode of DVT. Duplex scanning 6 weeks after diagnosis appears to be clinically useful for the identification of patients at risk of PTS.

Evaluation of the one-minute exercise test to detect peripheral arterial disease.

BACKGROUND: Asymptomatic peripheral arterial disease (PAD) is common amongst the elderly and is a risk factor for cardiovascular morbidity and mortality. PAD can be assessed by non-invasive tests such as the ankle/brachial pressure index (ABPI) at rest and Doppler flow velocity (DFV) scanning, but these tests may underestimate the prevalence of PAD. The aim of this study was to estimate the added value, for the detection of PAD, of the one-minute exercise test, defined as positive if the drop of the ankle systolic pressure was more than 30 mmHg. We also investigated whether the combination of the ABPI at rest and the one-minute exercise test could replace DFV scanning. MATERIALS AND METHODS: We studied this in a random sample (n = 631) of a 50- to 75-year-old population. RESULTS: Of these subjects 11% (66/631) had an abnormal ABPI (< 0.9) and 16% (102/631) had an abnormal DFV curve. Of this sample 72% of the subjects performed a one-minute exercise test. Of all subjects 6% (27/451) had an abnormal ABPI (< 0.9) and 12% (54/451) had an abnormal DFV curve. The one-minute exercise test revealed seven cases of PAD (beyond the 67 already identified) which were not detected by an abnormal ABPI at rest and/or DFV scanning. As a result the prevalence of PAD increased by 2%. All patients with an aortoiliac or femoropopliteal obstruction had an ABPI at rest < 0.9. The sensitivity of the combination of the ABPI at rest and the one-minute exercise test to detect abnormal DFV curves was low for crural obstructions. CONCLUSION: The one-minute exercise test slightly improves the detection of peripheral arterial disease in the general population.