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Biomedical subjects

N Labropoulos

Publications and source records attributed to N Labropoulos.

At least 73 records · Page 4Linked to original sources
PubMed1995

Venous reflux in symptom-free vascular surgeons.

PURPOSE: Work posture and occupation are among the most controversial predisposing factors associated with venous disease. We examined the distribution and extent of venous reflux in the lower extremities of symptom-free vascular surgeons, who were typically classified as leading a life of prolonged standing, in comparison to a group of symptom-free volunteers. METHODS: In this prospective study (January 1991 to April 1994), the venous system in the lower limb veins of 28 vascular surgeons (56 limbs) and 25 normal volunteers (50 limbs) was examined by color-flow duplex imaging. The two groups were matched for age (29 to 45 years) and sex (all men). Subjects with clinical signs and symptoms of venous disease, history of deep or superficial vein thrombosis, or previous venous operation or injection sclerotherapy were not included in the study (12 vascular surgeons). RESULTS: Venous reflux was detected in 29 limbs of vascular surgeons (52%) and in 16 limbs of the control group (32%) (chi-squared test = 4.232, p = 0.039). In the latter, superficial venous incompetence was detected in 9 of 50 limbs (18%), deep venous or perforator incompetence in 3 of 50 limbs (6%), and venous incompetence involving both the superficial and deep systems in 4 of 50 limbs (8%). In the group of vascular surgeons, reflux in the superficial veins was seen in 22 of 56 limbs (39%), in the deep and or perforating veins in 4 of 56 limbs (7%), and in both the superficial and deep veins in 3 of 56 limbs (5%). Superficial venous reflux was more frequently encountered in the limbs of 45% of vascular surgeons (25 of 56) than in the limbs of the control subjects 26% (13 of 50) (chi-squared test = 3.99, p = 0.047). Distal long saphenous vein reflux alone accounted for 39% (5 of 13) of any superficial venous incompetence in the limbs of the control subjects, and was higher, at 48% (12/25), in the vascular surgeons. Reflux in the gastrocnemial veins was equally distributed between the limbs of the control subjects (10%) and the vascular surgeons (11%). CONCLUSIONS: Venous reflux was more frequently seen among symptom-free vascular surgeons than normal individuals of a nonmedical vocation. The superficial system was by far the most common site of venous incompetence in both groups. Below-knee-long saphenous vein reflux in any combination was present in more than 75% of the limbs with superficial venous incompetence.

Adult↗
PubMed1995

Colour flow duplex scanning in suspected acute deep vein thrombosis; experience with routine use.

OBJECTIVES: To determine the accuracy of colour flow Duplex scanning (CFDS) in the diagnosis of deep vein thrombosis (DVT) and subsequently to investigate its diagnostic value in patients who have normal deep veins despite symptoms. DESIGN: Prospective open clinical study. SETTING: Vascular laboratory and radiology departments of University Hospital. MATERIALS AND METHODS: In the first part 112 limbs in 103 patients, 94 with symptoms of acute DVT and nine with pulmonary embolism (PE) were examined prospectively with CFDS and venography. Subsequently, in the second part, 328 legs in 304 patients were examined by CFDS alone for acute symptoms of DVT or PE. MAIN RESULTS: DVT was detected in 55 limbs by venography: proximal DVT was seen in 23 limbs, distal DVT in 25 limbs and both proximal and distal in seven limbs. CFDS was 100% sensitive and 98.8% specific in detecting proximal DVT whereas its sensitivity and specificity was 87.5% and 98.7% for distal DVT. Positive and negative predictive values were over 95% for both limb segments. The overall accuracy for the proximal DVT was 99.4% and for the distal 93.1%. In the second part, CFDS alone detected DVT in 156 limbs (47.6%); DVT was in the proximal segment in 82, distal segment in 61 and both in 13. In 172 limbs other causes of symptoms were identified in 34 (20%). CONCLUSIONS: We have demonstrated that CFDS is as accurate as venography when used by experienced operators. The average time of examination is 15-20 minutes and compares favourably with venography. Other causes of leg symptoms can also be diagnosed by CFDS in around 20% of patients who are found to have normal veins.

Humans↗
PubMed1994

Ultrasonic carotid artery plaque structure and the risk of cerebral infarction on computed tomography.

PURPOSE: The North American and the European Symptomatic Carotid Endarterectomy Trial investigators reported a conclusive benefit of carotid endarterectomy for patients with symptomatic 70% to 99% internal carotid artery (ICA) stenosis. However, it has been suggested that plaque structure may be an even more important factor in producing stroke than the degree of stenosis. The aim of this study was to test the hypothesis that the ultrasonic characteristics of carotid artery plaques were closely related to symptoms and to the prevalence of cerebral infarcts on computed tomography (CT). METHODS: One hundred five carotid artery plaques causing greater than 70% stenosis in the ICA in 83 consecutive patients who underwent brain CT were characterized into four ultrasonic types: echolucent plaques, predominantly echolucent plaques, predominantly echogenic plaques, and echogenic plaques. Patients with permanent neurologic deficit were excluded. RESULTS: There was a significant ipsilateral association between type 1 plaques and symptomatic hemispheres (p < 0.002). Twenty-six of the 105 cerebral hemispheres assessed by CT had infarcts. There was an increased incidence of brain infarcts in type I plaques (37%) compared with 18% in types II, III, and IV combined (p < 0.02). CONCLUSION: Our results support the hypothesis that echolucent plaques are more frequently associated with symptoms and cerebral infarctions and provide further evidence that these plaques are unstable and tend to embolize. Studies on the natural history of asymptomatic carotid artery stenosis should investigate whether plaque characterization could identify a high-risk group.

Arteriosclerosis↗
PubMed1994

Venous reflux in patients with previous deep venous thrombosis: correlation with ulceration and other symptoms.

PURPOSE: Deep vein thrombosis (DVT) in many cases leads to chronic symptoms in the damaged leg, even though the affected veins have recanalized. The major hemodynamic defect in such recanalized veins is reflux. The incidence and extent of reflux has been studied in patients with proven DVT and correlated with concurrent symptoms. METHODS: Two hundred seventeen limbs in 183 patients were examined by duplex scanning from January 1989 to October 1992. All limbs had previous DVT diagnosed by venography. Sites and extent (proximal, distal, or both) of reflux were identified by meticulous duplex scanning of the whole venous system and correlated with presenting symptoms. RESULTS: The patients were classified into nine groups on the basis of the classification of the system involved (superficial, deep, or superficial and deep) and whether the reflux was found proximal or distal to the knee or both. Eight-one limbs belong to chronic venous insufficiency class 1, 92 belong to class 2, and 38 belong to class 3. Reflux was confined to the deep venous system in 84 limbs (38.7%), to the superficial system in 31 (14.3%) limbs, and to both systems in 102 (47%) limbs. It was confined to proximal veins only in 48 (22.1%) limbs, distal only in 56 (25.8%) limbs and throughout the limb in 113 (52.1%) limbs. The incidence of swelling was increased by distal or a combination of proximal and distal reflux regardless of which system was involved. In limbs with superficial venous insufficiency (SVI) or deep venous insufficiency (DVI) only, the incidence of skin changes was not affected by the extent of reflux. However, in limbs with combined SVI and DVI, it was increased in the presence of reflux throughout the limb. Absence of distal reflux was associated with a low incidence of skin changes even in the presence of DVI. Ulceration increased with an increased extent of reflux in the presence of SVI. Absence of superficial reflux was associated with a low incidence, even in the presence of DVI. CONCLUSIONS: The data suggest that as far as the skin changes and ulceration are concerned, distal reflux and reflux in the superficial veins are more harmful than reflux confined to the deep veins, even when such reflux extends throughout the deep venous system.

Adolescent↗
PubMed1994

Superficial venous insufficiency: correlation of anatomic extent of reflux with clinical symptoms and signs.

PURPOSE: The aim of this study was to assess the distribution and extent of valvular incompetence in patients with reflux confined to the superficial venous system and correlate the extent of such reflux with clinical symptoms and signs. METHODS: Two hundred fifty-five limbs of 217 patients with superficial venous insufficiency and normal perforating and deep veins were examined with color-flow duplex imaging. One hundred twenty-three limbs (48.2%) of 102 patients had reflux confined to the long saphenous system, 83 limbs (32.6%) of 72 patients had reflux confined to the the short saphenous system, and 49 limbs (19.2%) of 43 patients had reflux in both long and short saphenous systems. RESULTS: In the long saphenous system the commonest pattern of reflux was that which extended throughout the length of long saphenous vein (LSV) (47%). Ache, swelling, and skin changes were common in the presence of below knee reflux irrespective whether the thigh segment was involved. Ulceration (8%) was found only in limbs with reflux extending throughout the length of LSV. In the short saphenous system the most common pattern of reflux extended throughout the length of short saphenous vein (SSV) (57%) without involvement of Giacomini or gastrocnemial veins. Ache and swelling were present in 62% and 72% of the limbs, but this incidence was not related to the extent of reflux. Swelling, skin changes, and ulceration occurred only when the whole of the SSV was involved. In the limbs with reflux in both the long and short saphenous systems, the most common pattern of reflux extended throughout the length of both systems (45%). In these limbs the incidence of swelling was 80%. The incidence of skin changes went from 44% when the below-knee segment of the LSV was involved to 73% when reflux occurred throughout the LSV and SSV. Ulceration (14%) was found only in the latter situation. Variable patterns of saphenogastrocnemial termination were seen. In 57.8% of the limbs SSV joined the popliteal vein just above the popliteal crease, whereas the SSV terminated in the thigh in 26.6%. CONCLUSIONS: We conclude that ache, ankle edema, and skin changes in limbs with reflux confined to the superficial venous system are predominantly associated with reflux in the below-knee veins. Ulceration is found only when the whole of the LSV is involved (8%) or when reflux is extensive in both LSV and SSV (14%).

Adolescent↗
PubMed1994

Duplex controlled angioplasty.

Duplex examination was carried out to assess lesions in peripheral arteries amenable to angioplasty. With the help of a special catheter, angioplasty of these lesions was performed under Duplex control. Sixteen patients presenting with claudication were examined by Duplex and 38 lesions were identified (31 stenoses, seven occlusions) and all the findings except one (vessel E1) were confirmed by subsequent angiography. Sixteen lesions were considered amenable to angioplasty and 13 lesions (in 10 patients) were selected for Duplex controlled angioplasty. A new catheter system which has a piezo-electric transducer at the centre of the balloon and integrated to a Duplex scanner via a catheter system interface, was used for the procedure. This allows the exact position of the balloon to be represented on the screen. Thirteen lesions (seven superficial femoral artery (SFA), three external iliac, two common iliac and one graft) were subjected to angioplasty under Duplex control. In one patient, the SFA was punctured directly under ultrasound control as the profunda was diseased. The guide wire was visualised in all cases and in the majority of cases, balloon size for the angioplasty was chosen by measurement of the arterial diameter by Duplex, which was also used for haemodynamic evaluation before, during and after the procedure. Eleven lesions (85%) underwent angioplasty entirely under Duplex control and additional X-ray control was needed in only two cases. In conclusion, Duplex allows the monitoring of both anatomical and haemodynamic parameters during angioplasty. It also reduces the risk of ionising radiation. Our initial experience has been encouraging as angioplasty was performed in the majority of lesions purely under Duplex control.

Angioplasty, Balloon↗
PubMed1994

Complications of the balloon assisted percutaneous transluminal angioplasty. Review article.

Percutaneous Transluminal Angioplasty (PTA), has become a widely used technique in the management of atherosclerotic and nonatherosclerotic stenoses or occlusions in almost all arterial segments. The long term success rate and the complication rate of the PTA have been reported to be equal to surgical intervention in selected indications. Despite the enormous literature on PTA, little attention has been given to the detailed identification of the etiology, the risk factors and the accepted range of the complications. The aims of this literature study are (a) to evaluate the safety of the balloon assisted PTA in the treatment of stenosed and occluded arterial lesions, (b) to provide detailed information on the etiology of complications, (c) to discuss the indications for the appropriate use of this procedure and (d) to identify the accepted complication rate.

Angioplasty, Balloon↗
PubMed1994

Acute and long-term effect of elastic stockings in patients with varicose veins.

The acute and long-term effect of elastic stockings has been evaluated in 20 patients (20 limbs) with grade 2 venous disease. The sites of venous reflux were determined with colour flow duplex scanning. Air Plethysmography was used to measure the amount of venous reflux and the ejecting capacity of the calf muscle pump. The patients were classified in to two different groups, A and B. Both groups of patients wore elastic stockings for four weeks. In group A (no. = 9) the measurements were done before, during and one day after the removal of the stockings, whereas in group B (no. = 11) the last measurements were done immediately after the removal of the stockings. Patients that showed improvement in their haemodynamics were re-examined a week later. Elastic compression appeared to be beneficial in both groups. The application of the elastic stockings improved reflux and the residual volume fraction in both groups and the ejecting capacity of the calf muscle pump in group B. Immediately after the removal of the stockings (Group B) all the measurements regressed to the initial values with the exemption of the residual volume fraction. However, one week later, the latter also regressed to the original value. It is concluded that the beneficial effect of elastic stockings on the venous haemodynamics is present mainly when the stockings are worn. It is completely abolished within a day after their removal.

Bandages↗
PubMed1994

Risk factors associated with recurrent carotid stenosis.

The incidence of restenosis following carotid endarterectomy reported with duplex scanning has ranged from 6-19%. The aim of this study was to determine the importance of risk factors in the development of carotid stenosis following carotid endarterectomy. Two hundred-thirty patients who underwent carotid endarterectomy (nineteen bilateral carotid endarterectomies) and had complete follow-up with duplex scanning for at least one year have been studied between February 1983 and April 1989. Forty six patients developed restenosis (18.5% of carotid endarterectomies) whereas 184 patients did not restenose. All patients were studied for the following risk factors: age, sex, ischemic heart disease, smoking habit, family history of cardiovascular disease diabetes mellitus, hyperlipidemia and peripheral vascular disease. The incidence of ischemic heart disease, a positive family history of cardiovascular disease, hyperlipidemia and diabetes mellitus was significantly increased (p < 0.05) in patients with recurrent carotid stenosis (80.4%, 71.7%, 58.7%, 32.6% respectively) as compared to patients without a recurrent stenosis (55.7%, 33.5%, 31%, 10.5%). None of the above significant risk factors was strongly associated with early (< 2 years) carotid restenosis. There is an increased prevalence of clinical atherosclerotic risk factors such as family history of cardiovascular disease, diabetes mellitus, ischemic heart disease and hyperlipidemia in patients who develop carotid restenosis.

Aged↗
PubMed1994

Laser Doppler skin perfusion pressure in normal and vascular subjects with rest pain: an universal measurement?

Laser-Doppler (LDF) skin perfusion pressure was measured and compared with Doppler ankle pressure measurements in 40 normal subjects and 20 patients with rest pain and ankle/foot Doppler pressure lower than 70 mmHg. Six different, commercially available LDF instruments were used. To obtain perfusion pressure a standard blood pressure cuff was used measuring the pressure at which the skin flux reading reached the biological zero level when inflating the cuff (P1) and the pressure at which the LDF tracing reappeared after deflating the cuff from sovrasistolic pressure level (P2). Perfusion pressure (PP) was considered to be the average [P1 + P2]/2. No differences in PP amongst the 6 instruments both in normal and vascular subjects were observed. These results indicate that PP is an universal LDF measurement which can be easily obtained with different LDF instruments.

Ankle↗
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↗