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To determine the relationship between ankle/brachial indices (ABIs) and morbidity and mortality in patients with peripheral arterial disease (PAD), a historical cohort study was performed. A total of 154 patients who had undergone noninvasive arterial assessment of the lower extremities in 1989 and 1990 were selected for this purpose. Selection criteria were age >40 years at the time of investigation, a resting ABI

Objective:A review of the published data on epidemiology, pathophysiology, diagnostic techniques and prevention of the post-thrombotic syndrome (PTS).Study selection:Studies, published between 1966 and 1996, identified through the medline database, and references cited in identified articles were included.Data synthesis:Deep venous thrombosis (DVT) may cause outflow obstruction and valve incompetence, resulting in venous hypertension. PTS is probably the effect of venous hypertension on the microcirculation. For qualitative anatomical and functional assessment of the venous system, duplex scanning is required, and for quantitative functional assessment, plethysmographic methods are the most suitable. The best treatment of PTS is its prevention by optimizing diagnosis and treatment of DVT and by prescribing and wearing elastic compression stockings. Until valid follow-up studies have been performed, distal DVT should not be neglected when assessing the PTS risk.Conclusions:PTS is a serious problem in terms of prevalence, complications (venous ulcers) and treatment with considerable socio-economic consequences. Duplex and plethysmography are valuable tools in its diagnosis and might be appropriate to identify patients at risk of developing PTS.

Apheresis of low-density lipoprotein (LDL) is an effective lipid-lowering treatment in hypercholesterolemic patients who have coronary artery disease and are refractory to drugs. More aggressive lipid-lowering therapy may further slow the progression of atherosclerosis.To compare the effect of LDL apheresis and simvastatin therapy with the effect of simvastatin therapy alone on the progression of peripheral vascular disease.Open, randomized, single-center study.University hospital.42 men with primary hypercholesterolemia (total cholesterol level8.0 mmol/L) and extensive coronary atherosclerosis.Biweekly apheresis of LDL plus simvastatin, 40 mg/d (n = 21), or simvastatin, 40 mg/d (n = 21), for 2 years.Lipid and lipoprotein levels, changes in hemodynamically significant stenoses in the aortotibial tract (measured by ankle:arm systolic blood pressure ratio combined with Doppler spectrum analysis of the femoral artery), and changes in the mean intima-media thickness of three carotid artery segments.Mean baseline LDL cholesterol levels decreased from 7.8 to 3.0 mmol/L in the apheresis and simvastatin group and from 7.9 to 4.1 mmol/L in the simvastatin-only group; mean lipoprotein(a) levels decreased from 57.0 to 44.5 mg/dL (change, -19%) in the former group and increased from 38.4 to 44.5 mg/dL (change, 15%) in the latter group. In the apheresis group, the number of patients with hemodynamically significant stenoses in the aortotibial tract decreased from 9 to 7; in the simvastatin-only group, the number increased from 6 to 13 (P = 0.002). Mean intima-media thickness decreased by a mean +/- SD of 0.05 +/- 0.34 mm in the apheresis group and increased by 0.06 +/- 0.38 mm in the simvastatin-only group (P0.001). According to multiple regression analysis, changes in apolipoprotein B, total cholesterol, and lipoprotein(a) levels accounted for changes in the aortotibial tract (R2 = 0.36); changes in lipoprotein(a) and apolipoprotein A1 levels accounted for changes in the intima-media thickness of the carotid artery (R2 = 0.49).Aggressive lipid lowering with simvastatin and LDL apheresis decreased the intima-media thickness of the carotid artery and prevented an increase in the number of hemodynamically significant stenoses in the lower limbs. Therapy with simvastatin alone did not prevent progression of carotid or aortotibial vascular disease.

The purpose of this study was to examine the difference in: (1) effective muscle pump activity (MPA) between voluntary and electrically (ES) induced contractions in able-bodied subjects (ABS); and (2) ES-induced MPA between spinal cord-injured (SCI) individuals and ABS. MPA was measured as relative volume changes in the calf using strain-gauge plethysmography during repeated muscle contractions in the supine position while venous outflow was impeded by a thigh cuff inflated to a range of pressures. Ten SCI individuals and ten ABS participated in this study. ABS showed no significant difference between voluntary and electrically induced MPA [58.1 (18.4)% versus 67.7 (8.7)%, respectively]. SCI individuals showed a significantly lower ES-induced MPA than ABS [21.5 (15.9)% versus 67.7 (8.7)%, respectively]. The low MPA in SCI individuals may be explained by: (1) extensive leg muscle atrophy and/or (2) an “atrophic” vascular system in the legs. The electrical current level seemed to influence MPA (43 mA, 21.5% versus 60 mA, 30.8%) for SCI individuals, whereas no influence of muscle contraction rate on MPA was observed in ABS. The results of this study demonstrate that although ES-induced leg muscle contractions result in adequate MPA in ABS, it leads to significantly less effective MPA in SCI individuals.

Purpose: Venous hemodynamics were evaluated in relation to the postthrombotic syndrome (PTS) 7 to 13 years after deep venous thrombosis (DVT). Methods: The presence of flow, reflux, and compressibility of 1394 vein segments in 82 patients was assessed by means of duplex scanning. The venous outflow resistance was measured by means of strain-gauge plethysmography. The venous hemodynamics were related to the clinical severity of the PTS, characterized by the CEAP (clinical, etiologic, anatomic, pathophysiologic) classification. Results: In patients with severe clinical symptoms of PTS, the prevalence of reflux was significantly higher. There was no relationship between the severity of the PTS and the noncompressibility or the combination of reflux and noncompressibility or an increased venous resistance. By means of multiple regression analysis with the variables of age, gender, reflux, and venous resistance, age and reflux were shown to be the main contributors to the severity of PTS. Significantly more patients (64%) with severe signs of PTS had a combination of deep and superficial reflux. In each of the traceable vein segments, the mean of the CEAP classification was calculated for the vein segments with and without reflux. In the proximal superficial femoral vein (P < .001), distal superficial femoral vein (P < .05), and popliteal vein (P < .05), a significantly higher mean CEAP classification was found in the veins with reflux, whereas in the distal, long, and short saphenous veins, no such relationship was found. Conclusion: Most patients with severe PTS had a combination of deep and superficial reflux. Reflux in the deep proximal veins contributes significantly to the PTS. (J Vasc Surg 1999;29:1071-6.)

1. The purpose of the study was to evaluate the degree of thrombus regression, development of valvular insufficiency, impaired calf muscle pump function and clinical symptoms after a period of acute deep venous thrombosis. 2. Seventy patients with acute deep venous thrombosis, diagnosed by duplex scanning or venography, received treatment with heparin and oral coumarin derivatives according to a standard protocol. All patients wore graduated compression stockings during the whole study period. Duplex scanning was performed at diagnosis and 1 and 3 months later to measure thrombus mass and reflux. The supine venous pump function test was used to assess calf muscle pump function. 3. Three months follow-up was completed in 60 patients. In total 218 (28%) out of 780 vein segments were initially thrombosed and 134 (17%) could not be traced. A statistically significant reduction of thrombus mass was recorded throughout the study period. Total resolution of thrombosis in all vein segments occurred in 25% of the patients within 1 month and in 40% in 3 months. There was no difference in regression between the various proximal vein segments. Distal segments showed more regression than proximal segments. Reflux occurred in 27% of the initially thrombosed veins and in 15% of the patent veins. Patients who showed total resolution after 1 month had a significantly higher calf muscle pump function than patients without total resolution (70%pf vs 61%pf, P < 0.05). Patients with reflux in two or more segments had a significantly lower calf muscle pump function than patients with reflux in less than two segments (58%pf vs 69%pf, P < 0.05). 4. Using duplex scanning and the supine venous pump function test 3 months after an acute deep venous thrombosis, overall haemodynamic abnormalities and local site of valve incompetence could readily be identified. Patients with haemodynamic abnormalities might be at risk to develop the post-thrombotic syndrome. There was no difference in thrombus regression between the various proximal vein segments. Reflux was significantly more often seen in initially thrombosed veins. Thirty-five percent of the patients developed an abnormal calf muscle pump function after 3 months. Patients with early resolution of thrombus had a higher calf muscle pump function after 3 months.

Adequate patient selection is required to limit the clinical workload and improve the cost-effectiveness of noninvasive hemodynamic evaluation of the aortoiliac system. In a prospective blinded fashion the traditional invasive technique of direct femoral artery pressure measurements and the computerized Doppler spectrum analysis of blood flow velocities in the common femoral artery were studied. Both tests for rapid assessment of aortoiliac obstruction were compared with duplex ultrasonographic imaging, using a peak systolic velocity ratio of 2.5 to demonstrate stenoses of 50% or more. In a series of 17 consecutive patients (34 aortoiliac segments) with suspected aortoiliac obstructive disease, a good level of agreement (kappa = 0.6) was found for both methods when compared with duplex scanning. Analysis of deviations from the duplex registrations indicated an overestimation of the pathologic cases using femoral artery pressure measurements and an underestimation using Doppler spectrum analysis of blood flow velocities in the common femoral artery. Both methods were well tolerated, but femoral artery pressure measurements had a higher technical failure rate. Because of its noninvasive character and its feasibility the Doppler technique is preferred for the selection of patients for more extensive duplex sonographic investigation.

Because clinical signs and symptoms are unreliable the diagnosis of deep vein thrombosis (DVT) should be objectified. Advantages and disadvantages of contrast venography, plethysmography, ultrasound techniques, fibrinogen leg scanning, computer-assisted tomography, magnetic resonance imaging and blood tests are discussed. In patients with a first event of suspected DVT non-invasive methods like serial plethysmography or ultrasound testing are sensitive and specific enough to make a treatment decision. It is safe to withhold anticoagulants if the test remains normal within 1 week. In patients with suspected recurrent DVT new non-invasive techniques are being tested, but up to now the definitive objective diagnostic test continues to be contrast venography. In first period as well as in recurrent DVT D-Dimer testing could be an additional test to exclude active thromboembolism.

Objectives. In patients with familial hypercholesterol­ aemia (FH), the prevalence of haemodynamically significant peripheral vascular disease (PVD) was measured in relation to lipoproteins, general risk factors and the presence of coronary artery disease (CAD). Design. A case control study. Setting. The outpatient lipid clinic of a university hospital (tertiary referral centre). Subjects. Patients with heterozygous FH [n = 6 8 ; age 4 5 .8 ± 1 1 .6 years; untreated LDL-cholesterol 9.2 ± 2 .0 mmol L-1] were compared with control subjects m atched for gender, age, weight, smoking and presence of hypertension [n~27\ age 44.0 years; LDL-cholesterol 3 .8 ± 1 .3 mmoIL"1 ]. Main outcome measures. PVD was assessed during cholesterol-lowering treatm ent using ankle/arm blood pressure ratios and analyses of Doppler-derived blood flow velocities in the femoral artery at rest and during reactive hyperaemia. The diagnosis of CAD was assessed clinically. Results. Haemodynamically significant PVD was found in 21 (31%) FH patients and in one (3.7%) control subject, predominantly localized in the femoro-popliteal vessels. CAD was present in 30 (44.1%) FH patients and in one (3.7%) control subject. PVD could be demonstrated in 50% of FH patients with CAD [relative risk 3.2 (95% Cl 1 .4 - 7 .2 )] and in 19% as the first manifestation of vascular disease. Males and females were equally affected. Mean arterial blood pressure of FH patients with PVD was higher compared to FH patients without PVD. Conclusions. Haemodynamically significant PVD appears to be more prevalent in FH patients than is generally assumed, especially in those with CAD. A relation with lipoprotein levels could not be demon­

Publisher Summary This chapter makes a comparison between psychophysical and saccadic responses to near threshold visual stimuli. There exists an inverse relationship between the contrast detection threshold and stimulus duration for stimuli up to a certain duration. The interval of this linear summation has been shown to be about 60 ms for luminance contrast stimuli and about 200 ms for chromatic stimuli equiluminant to the visual field. For saccadic measurements the observer has to respond by making a saccade to the stimulus at every stimulus presentation. The contrast detection threshold is defined as the point at which 80% of the responses are correct. The probability of evoking a correct saccade depends on the duration of a stimulus both for luminance contrast stimuli and for chromatic stimuli. The spatiotemporal properties of visual stimuli affect saccadic responses in the same way as for psychophysical responses.