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Biomedical subjects

N Labropoulos

Publications and source records attributed to N Labropoulos.

63 records · Page 4Linked to original sources
PubMed1993

Characterization of symptomatic and asymptomatic carotid plaques using high-resolution real-time ultrasonography.

High-resolution ultrasonography was used to classify carotid plaques into five different types in 72 patients with symptoms and in 49 without, and with stenosis of the origin of the internal carotid artery > 70 per cent. There were 72 plaques in the symptomatic group and 75 in the asymptomatic group. Type 1 plaques were uniformly echolucent, type 2 predominantly echolucent, type 3 predominantly echogenic, type 4 uniformly echogenic and type 5 consisted of plaques that could not be classified owing to heavy calcification and acoustic shadows. Type 1 plaque was found in 90 per cent of patients with symptoms and in 10 per cent of those without, type 2 plaque was found in 53 and 47 per cent, type 3 in 34 and 66 per cent, and type 4 in 5 and 95 per cent, respectively. The preponderance of echolucent plaques in symptomatic patients with stenosis > 70 per cent supports the hypothesis that this type of plaque is unstable and tends to embolize. In contrast, in patients without symptoms there is preponderance of echogenic plaques.

Arteriosclerosis↗
PubMed1993

Detection of superior mesenteric and coeliac artery stenosis with colour flow Duplex imaging.

Measurements of blood velocity in the coeliac axis (CA) and the superior mesenteric artery (SMA) before and after a standard meal in normal people have been studied by several authors. However, information about the ability to detect stenotic lesions is lacking. The aim of our study was to determine the accuracy of Duplex scanning in detecting angiographically proven lesions. Twenty normal volunteers (13 males and seven females) and 24 patients (19 males and five females) with visceral artery stenosis on angiography were examined in the supine position (angle of insonation 60.5) with colour flow Duplex imaging (CFDI) (3.5 MHz probe), in the fasting state and after a standard meal at 15, 40, 60 and 90 min. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were determined in both CA and SMA. The PSV was the best indicator of stenosis. After the meal, there was an increase in both PSV and EDV but neither of the postprandial measurements improved the accuracy of the test. The results indicate that CFDI can detect the presence of significant stenosis (> 50% in the CA and SMA with a sensitivity and specificity of > 80%.

Arterial Occlusive Diseases↗
PubMed1993

The effect of iloprost in patients with rest pain.

Thirty-four patients with ischaemic rest pain in 42 limbs and ankle pressure equal to or less than 50 mmHg have been treated with intravenous infusion of synthetic prostacyclin (iloprost) for eight days. Leg blood flow was measured with air plethysmography before treatment, on day 4 and day 8 of treatment. Total relief of pain for at least 6 weeks occurred in 91% of patients with leg blood flow > or = 40 ml/min, in 18% with leg flow 30-39 ml/min and in 11% with leg flow < 30 ml/min. Complete relief of pain for at least 6 weeks occurred in 92% of patients in whose limbs the blood flow on day 8 was greater than 50 ml/min but only in 6% with blood flow less than 50 ml/min. These results indicate that iloprost increases leg blood flow and that patients likely to respond can be identified from the baseline air plethysmographic measurement of leg blood flow.

Arteriosclerosis↗
PubMed1993

Progression of carotid atherosclerosis. Three year follow-up and analysis of risk factors.

OBJECTIVE: To elicit the risk factors associated with increasing grades of stenosis in patients with carotid plaque. STUDY DESIGN: Retrospective review of serial duplex scans of the carotid bifurcation. Case note review for documented risk factors. SETTING: Irvine Laboratory of the Academic Department of Surgery, Vascular Section. PATIENTS AND RESULTS: Review of serial duplex scans of the carotid bifurcation was performed on 200 unselected patients who each had a follow-up of at least three years. Definite progression of carotid atherosclerosis was defined as an unequivocal increase in at least one grade by the criteria of Strandness, and was documented in 50 patients (25%). Even if the initial situation is normal or minimal disease (< 15% stenosis), once definite plaque progression is observed, the lesion will progress to a hemodynamically significant one (> 50%) in 67% of this patient population. The only risk factor for plaque progression that we defined is hypertension, and this may be spurious. There are no risk factors associated with the subgroup of plaques that progress rapidly above those that progress at a slower rate. CONCLUSIONS: There are no risk factors defined in this population which are associated with advancing carotid atherosclerosis.

Aged↗
PubMed1993

The effect of elastic stockings on the elasticity of varicose veins.

The aim of this study was to establish the long-term effect of graduated elastic compression on venous elasticity in patients with superficial or deep venous disease and to determine the possible relationship between elasticity and the duration of the disease. The elastic modulus of 29 patients, 19 with superficial vein incompetence and 10 with deep vein incompetence was assessed by the simultaneous measurement of calf volume (determined using strain gauge) and venous pressure (obtained via a dorsal foot vein) during venous occlusion. The measurements were obtained before and after 4 weeks of elastic compression stockings. The elastic modulus K, was defined as stress/strain when the veins were full and was calculated from the pressure/volume relationship. The results show a clear difference in elasticity before and after elastic stockings. Two groups of patients were identified: group 1 with increased elasticity and group 2 with decreased elasticity. There was a negative linear relationship (r = 0.88) between increase in elasticity after treatment and duration of venous disease.

Bandages↗
PubMed1993

Noninvasive tests in venous insufficiency.

Chronic venous insufficiency (CVI) is the result of outflow obstruction, reflux or a combination of both. Noninvasive tests detect an quantify obstruction and reflux if present and define the anatomic localisation of the abnormality. In evaluating CVI noninvasive tests combine physiologic and imaging techniques. These tests are widely available, simple, quick and cost-effective and therefore they are the methods of choice for initial objective evaluation. Different tests provide answers to different questions. The optimum clinically useful information can be now obtained using only three instruments: pocket Doppler, duplex or color duplex scanner and air plethysmography. The value of ambulatory venous pressure, photoplethysmography and light reflection reography, air plethysmography, duplex and color duplex scanning to assess reflux and the value of tests to assess out-flow obstruction are presented. Pooled data collected from large studies are also presented for reference. Qualitative and quantitative assessment of CVI are useful both for clinical assessment and to evaluate the effect of treatments.

Chronic Disease↗
PubMed1992

The combination of liquid crystal thermography and duplex scanning in the diagnosis of deep vein thrombosis.

One hundred patients with clinically suspected deep vein thrombosis (DVT) were studied by liquid crystal thermography (LCT), duplex scanning and venography. Liquid crystal thermography was found to have a negative predictive value of 97% if performed within 1 week of the onset of symptoms. Duplex scanning had a sensitivity of 93% and specificity of 91% for all thrombi (proximal and calf). On the basis of these results a plan of investigation has been formulated that would avoid duplex scanning and venography in 39 of the 100 patients. Duplex scanning alone would be appropriate in 56 of the remaining 61 patients. Only six patients would be unsuitable for duplex scanning because of a very tense tender leg and require venography. The plan would miss one calf thrombus and result in treating three patients unnecessarily. This policy would be not only effective but also cost-effective.

Female↗
PubMed1992

Popliteal vein entrapment in the normal population.

The aim of this study was to determine the incidence and severity of popliteal vein compression by full knee extension in the normal population. The popliteal veins in 100 healthy volunteers (200 limbs) with no history of previous deep vein thrombosis (DVT) or venous obstruction were examined using duplex scanning with the knee slightly flexed and then fully extended. Knee extension produced complete obstruction in 17 subjects and severe obstruction (< 50% decrease in diameter) in a further 10 subjects. Thirteen subjects had unilateral compression and 14 bilateral. The 27 subjects were tested for functional venous outflow obstruction with air plethysmography. In flexion, the outflow fraction was normal (> 40%) in all subjects. With the knee fully extended, severe or complete venous obstruction (outflow fraction < 10%) was found in eight subjects. Moderate obstruction (outflow fraction 10-40%) was found in all the remaining 19 subjects. When digital compression of the long saphenous vein was performed, these subjects also demonstrated severe outflow obstruction. Although the incidence of symptoms of functional venous obstruction is rare in the general population, these findings have important implications for venous stasis for patients on the operating table and in those having prolonged bed rest. Studies investigating the association between popliteal vein compression and postoperative deep venous thrombosis are needed.

Adult↗