Is there a place for duplex screening of brachial artery in haemodialysis patients with vascular access?

BACKGROUND: Vascular access (VA) stenosis with subsequent thrombosis remains one of the major causes of morbidity and hospitalization in haemodialysis patients. The present cross-sectional study was planned in order to analyze the usefulness of brachial artery duplex ultrasound for detection and prediction of vascular access stenoses. METHODS: Color duplex ultrasound (Apogée Cx200, sectorial probe 7.5 MHz) was used to obtain the anatomical pattern of the VA and flow velocity waveforms of the brachial artery in 77 non-selected VA (47 Ciminio-Brescia fistulae and 30 PTFE grafts). In each VA, the resistance index (RI), the mean blood flow rate (Q) and the blood flow ratio index (QI) (QI = VA flow rate/contralateral flow rate) were calculated at the level of the brachial artery. The sensitivity and specificity of these brachial Doppler parameters were calculated for the detection of VA stenosis. In normal VA, positive (PPV) and negative predictive (NPV) values were calculated for the development of clinical stenotic complications 3 months post ultrasound examination. RESULTS: Thirteen of the 77 VA (17%) were identified as stenosed by duplex ultrasound and confirmed by fistulography and/or during surgical exploration. The best screening tests for VA stenosis detection were a QI threshold < 4.0 with a sensitivity and specificity of 69 and 69% and an RI > 0.55 with a sensitivity and specificity of 62 and 66%, respectively. In the VA considered as normal by ultrasound, the prediction of subsequent stenosis within three months post-ultrasound examination gave a PPV of only 18% and 19% for RI and QI, respectively. NPV for RI and QI were 90% and 88%. CONCLUSIONS: While Doppler ultrasound is a useful non-invasive test for the detection of prevalent VA stenosis, our results do not confirm that abnormal brachial Doppler flow parameters can predict short term development of VA stenosis.

[Reference values of intima-medial thickness of carotid and femoral arteries in subjects aged 20 to 60 years and without cardiovascular risk factors]. / Valeurs de référence des épaisseurs intima-média des artères carotidiennes et fémorales chez des sujets âgés de 20 à 60 ans et sans facteur de risque cardiovasculaire.

Many studies have shown a close correlation between intima-medial thickness of the carotid artery measured by high resolution ultrasonography and the presence of coronary artery disease or atherogenic risk factors. However, reference values for the value of intima-medial thickness (IMT) in healthy subjects have not yet been established. The aim of this study was, therefore, to determine the reference values of carotid (C-IMT) and femoral intima-medial thickness (F-IMT) with respect to age and gender in healthy subjects (53 women and 45 men) aged 20 to 60, with no family or personal history of cardiovascular disease or atherogenic risk factors, underwent high resolution colour echo-Doppler examination. The mean C-IMT was 556 +/- 57 microns in women and 573 +/- 70 microns in men (NS), and the femoral equivalent was 543 +/- 63 microns in women and 562 +/- 74 microns in men (NS). Between the ages of 20 and 60, the C-IMT increased by 1.8 microns per year (p < 0.03) in women and 3.4 microns (p < 0.001) in men, the variations being respectively 1.2 microns (NS) and 3.1 microns (p < 0.002) in the femoral artery. Multiple regression analysis including gender and individual values of age, body mass index and lipid profile confirmed that only age was significantly correlated to the increase in thickness. The authors conclude that the reference values of IMT do not differ with gender or site of analysis, but there is a slight influence with respect to age.

[The measurement by high resolution ultrasound of the intima-media thickness at the carotis comunis artery: early marker of atherosclerosis]. / La mesure echographique de l'epaisseur de l'intima-media de I'artêre carotide commune: marqueur précoce de l'athérosclérose.

Since 1986, published from the P. Pignoli's group in Italy, the measurement by B-Mode Ultrasound of the carotid Intima Media Thickness is considered a very important tool for the assessment of cardiovascular risk in epidemiological trials but also for pharmacological studies. After more than 20 years the improvement of the technology in Ultrasound systems and the computer semiautomatic assisted analysis has permitted the standardisation of the method as suggested in the Mannheim and Brussels 2004-2006 Consensus. In vivo carotid IMT analysis is probably the first step for the evaluation of beginning and early atherosclerosis even before detectable lesions defined as plaque are observed. In particular situations by patients with high cardiovascular risk, the measurement of the IMT can be helpful for the decision to treat them more aggressively even in primary prevention.

[Anatomy by ultrasound of the veins in the leg: essentials]. / Anatomie ultrasonique du réseau veineux: Connaissances essentielles.

Studying the anatomy of lower extremity veins is a tedious and complex task. Although huge efforts have been undertaken to create harmonization, any global description of the venous network is encumbered by the large number of superficial and deep veins, anastomoses and collaterals, and not least by a vastly broad nomenclature. Innumerable anatomic variants contribute to creating a complicated picture. What is needed is a description that correspondingly reflects the reality. Yet, does our description reproduce the actual anatomic and pathologic circumstances? As a rule, a phlebography is performed to localize an acute or chronic venous condition. The examiner must have learn about the "healthy" to What the stethoscope is to a cardiologist, the Doppler sonography transducer was to the phlebologist, an indispensable tool. Nowadays, duplex sonography has to be called the gold standard in that it supplies the most comprehensive information for diagnosing functional disorders of the venous system, thereby enabling a clear therapeutic strategy to be delineated. Most qualitatively average or high-grade ultrasound machines are equipped with duplex sonography, which today's specialists can employ to highly efficiently render a differential diagnosis of deep vein thrombosis. Given the ethic and forensic background and the potentially lethal outcome of a misdiagnosis, the use of this diagnostic tool must be exclusively reserved for physicians with a particularly high level of skill and training. The specialist societies for ultrasonography, angiology and phlebology have published strict guidelines for teaching Doppler sonography in Switzerland.

In-vitro motility of normal and pathological smooth muscle of colon.

This study is based on the in-vitro analysis of the normal and pathological colon smooth muscle contraction. Two different methods, supported by computer analysis, are presented. This approach will probably help the physician and the surgeon to better understand the physiopathology of some characteristical diseases, such as Hirschsprung's disease.