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Biomedical subjects

N Labropoulos

Publications and source records attributed to N Labropoulos.

At least 55 records · Page 3Linked to original sources

The role of common carotid artery end-diastolic velocity in near total or total internal carotid artery occlusion.

OBJECTIVES: To evaluate the role of the end-diastolic velocity (EDV) in the common carotid artery (CCA) as a marker of internal carotid artery (ICA) occlusion. DESIGN: Validation of retrospective data in a prospective clinical study. METHODS: The EDV in 94 patients with total ICA occlusion and in 24 patients with high grade (95-99%) unilateral ICA stenosis identified on extracranial carotid colour-flow Duplex imaging (CFDI) and arteriography was reviewed, and was retrospectively compared to the EDV of 176 normal individuals. Identification of patients with ICA occlusion was most accurate (99.3%) with an ipsilateral EDV > or = 12 cm/s and a DIFF > or = 10 cm/s (DIFF = contralateral EDV -- ipsilateral EDV). These values were then prospectively applied to all 886 patients (67 with high grade stenosis or occlusion) who underwent CFDI at our institution during 1994. RESULTS: The EDV > or = 12 had a 92% sensitivity, a 99.4% negative predictive value (NPV) and a 85% specificity in distinguishing between occluded and patent ICA's. In combination with a DIFF > or = 10 was 80.4% sensitive and 97.5% specific. The positive predictive value of the EDV > or = 12 in the distinction between 95-99% ICA stenosis and ICA occlusion was 78.3%, and that of the combination was 85.4%. The EDV was rarely zero and 10% of patients with normal or minimally diseased ICA's had an EDV > or = 12 and/or a DIFF > or = 10. CONCLUSIONS: The EDV < or = 12 cm/s is a sensitive marker of ICA occlusion with a high NPV and in combination with the DIFF > or = 10 cm/s, is specific. Nevertheless, EDV parameters are inaccurate in the distinction of 95-99% ICA stenosis from occlusion. Low EDV can be found in a number of patients with minor or no ICA disease, particularly in those with a stroke or silent cerebral infarct.

Adult↗

Laser Doppler flux in normal and arteriosclerotic carotid artery wall.

The perfusion of the arterial wall was evaluated in vivo in normal sections of the carotid artery, in sections with fibrotic plaques and in sections with plaques and diffuse calcifications using laser Doppler flowmetry. Patients with carotid plaques undergoing carotid endarterectomy were studied. Using intra-operative ultrasound three different levels of atherosclerosis involvement of the arterial wall were defined: normal arterial wall where all components (intima, media and adventitia) were clearly separated and intact; wall with intima-media thickening and fibrotic plaques (without calcifications); sections with diffusely calcified plaques. In 20 patients 20 normal sections, 20 sections with fibrotic plaques and 20 sections with large plaques and diffuse calcifications were studied. Diabetic and hypertensive patients were excluded. Wall flux was measured on the external surface of the common carotid artery before complete dissection for endarterectomy. Measurements were recorded when at least 3/4 of the adventitia was intact for a length of at least 4 cm. The average flux in normal sections was higher (p < 0.05) than in sections with fibrotic plaques and in sections with calcified plaques. A significant difference in flux (p < 0.05) between fibrotic (decreased flux) and calcified areas (very low flux) was recorded. In conclusion a higher wall perfusion was observed in normal arterial sections in comparison with sections with plaques. Sections with diffuse calcifications and larger plaques had a very low flux.

Aged↗

The impact of duplex scanning on vascular practice.

Duplex ultrasonography has gained enormous importance in the vascular practice over the last decade. Technological development with the colour application as well as the high resolution imaging have altered the diagnostic approach, treatment and follow-up of the vascular patients. Research on the epidemiology and natural history of atherosclerosis and thrombosis has also been founded based on the ultrasonic applications, improving our understanding in the pathophysiology of the vascular disease. This article presents an overview of the revolutionary role of the ultrasonic investigations in the arterial and venous disease and outlines the possible limitations of the technique. Financial aspects of its use in the health care system and potential advents in the near future are also discussed.

Aortic Diseases↗

Venous hemodynamic abnormalities in patients with leg ulceration.

PURPOSE: Venous ulceration in the leg has been predominantly associated with deep venous insufficiency, although a few reports have implicated the superficial veins. The aim of this study was to identify the distribution of valvular incompetence in patients with active leg ulceration. PATIENTS AND METHODS: Color flow duplex imaging (CFDI) ultrasonography was used to evaluate the entire venous system--superficial, perforator and deep--from groin to ankle in 112 limbs of 94 patients with venous leg ulcers. RESULTS: Seventy two limbs (64%) had multisystem incompetence and 36 (32%) had one system involved only, whereas in 4 limbs (4%) there was no venous incompetence. Deep venous reflux exclusively was present in 7 limbs (6%) and the perforator system alone was involved only in 3 limbs (3%). However, isolated superficial incompetence was seen in 26 extremities (23%) and combination of superficial with perforator system alone in 23 (21%). In addition, reflux overall in the superficial system (alone and in combination with perforator and deep systems) was seen in 94 limbs (84%). The most common pattern (28%) of abnormality was reflux in all systems, superficial, perforator, and deep. CONCLUSIONS: The results of this study show that variable combined patterns account for over two thirds of patients with ulceration. No comprehensive surgical policy for alleviating ulceration can be justified; we suggest that a complete evaluation of all venous systems from groin to ankle with CFDI ultrasonography in patients with venous ulceration is practical on a routine basis and will be particularly valuable before surgery in order to target intervention at specific incompetent sites.

Adolescent↗

New insights into the pathophysiologic condition of venous ulceration with color-flow duplex imaging: implications for treatment?

PURPOSE: This study was conducted to investigate the distribution of reflux in the veins adjacent to or within the venous ulcer (local) and to correlate it with the pattern of disease of the axial veins (all veins away from the ulcer area) of the affected limb. METHODS: Forty-three ulcers in 34 legs of 33 patients were examined with color-flow duplex imaging. The veins in the area of the ulcer were scanned with a sterile technique. RESULTS: In 17 legs (50%) there was documented past deep venous thrombosis. All of the 34 limbs had reflux in the superficial or deep axial veins either alone or in combination. Fifteen of these limbs (44%) also had perforating vein incompetence, but none had perforator incompetence alone. Six ulcers showed no evidence of reflux in the local veins when scanned through the ulcer bed despite the presence of reflux in the axial veins of the limb. In 13 limbs with 17 ulcers, either the superficial axial veins alone or the deep axial veins alone were affected (with or without associated perforator incompetence). Examination of the local veins associated with these 17 ulcers revealed a similar pattern of reflux to that seen in the axial veins in 13 cases, with the remaining 4 ulcers showing no local venous abnormality. The pattern of reflux was less predictable at the local ulcer level in limbs where both superficial and deep venous incompetence coexisted in the axial veins. Only 7 of the 26 ulcers (27%) in these limbs had similar evidence of combined superficial and deep reflux in the local ulcer veins, whereas 10 ulcers (39%) were associated with local reflux in the superficial or deep veins alone. CONCLUSIONS: These data show that 86% (37/43) of the ulcers has some degree of reflux in the local area, the pattern of which may differ from the axial vein disease. Treatment of the local hemodynamic abnormalities may be an important factor in the healing of the ulcers and in the prevention of their recurrence.

Adolescent↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗