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Stavros K Kakkos

Publications and source records attributed to Stavros K Kakkos.

11 recordsLinked to original sources
PubMed2006

Effect of zooming on texture features of ultrasonic images.

BACKGROUND: Unstable carotid plaques on subjective, visual, assessment using B-mode ultrasound scanning appear as echolucent and heterogeneous. Although previous studies on computer assisted plaque characterisation have standardised B-mode images for brightness, improving the objective assessment of echolucency, little progress has been made towards standardisation of texture analysis methods, which assess plaque heterogeneity. The aim of the present study was to investigate the influence of image zooming during ultrasound scanning on textural features and to test whether or not resolution standardisation decreases the variability introduced. METHODS: Eighteen still B-mode images of carotid plaques were zoomed during carotid scanning (zoom factor 1.3) and both images were transferred to a PC and normalised. Using bilinear and bicubic interpolation, the original images were interpolated in a process of simulating off-line zoom using the same interpolation factor. With the aid of the colour-coded image, carotid plaques of the original, zoomed and two resampled images for each case were outlined and histogram, first order and second order statistics were subsequently calculated. RESULTS: Most second order statistics (21/25, 84%) were significantly (p < 0.05) sensitive to image zooming during scanning, in contrast to histogram and first order statistics (4/25, 16%, p < 0.001, Fisher's exact test). Median (interquartile range) change of those features sensitive to zooming was 18.14% (4.94-28.43). Image interpolation restored these changes, the bicubic interpolation being superior compared to bilinear interpolation (p = 0.036). CONCLUSION: Texture analysis of ultrasonic plaques should be performed under standardised resolution settings; otherwise a resolution normalisation algorithm should be applied.

Algorithms↗
PubMed2006

Effectiveness and safety of ultrasound-guided foam sclerotherapy for recurrent varicose veins: immediate results.

PURPOSE: To evaluate the effectiveness and safety of ultrasound-guided foam sclerotherapy in treating recurrent varicose veins. METHODS: Between July 2003 and January 2005, 38 outpatients (25 women; median age 59 years, interquartile range 53.5-66.0) with recurrent varicose veins in 45 legs were treated. Ultrasound was used to identify sites of reflux. The Tessari method was used to produce foam using 3% sodium tetradecyl sulphate; up to 6 mL of foam was injected per session under ultrasound control. Results are shown as median (interquartile range). RESULTS: A single sclerotherapy session was adequate in 26 (58%) legs. In 87% of all legs, complete elimination of both varicose veins and all reflux points was achieved. A positive association between the amount of injected foam and CEAP class (r=0.45, p=0.002) and venous clinical severity score (r=0.37, p=0.012) was found. There was a trend for more sclerotherapy sessions [median 2 (1-2)] in legs with incomplete saphenofemoral junction/ great saphenous vein (GSV) ligation or accessory GSV (n=16) to achieve varicose vein ablation versus legs with other primary sites of reflux [median 1 (1-2), p=0.12]. There were no instances of deep vein thrombosis or systemic complications; superficial thrombophlebitis occurred in 6 (8.2%) of the 73 injection sessions. Legs with proximal reflux due to previous incomplete ligation or fed by an incompetent pelvic vein experienced superficial thrombophlebitis more frequently (4/12, 33%) than legs without proximal reflux [1/33 (3%); OR 16, 95% CI 1.6-164, p=0.014]. CONCLUSION: In most patients, ultrasound-guided foam sclerotherapy is a safe treatment for recurrent varicose veins, with an excellent immediate result. However, the presence of proximal reflux may decrease the immediate results and predispose to superficial thrombophlebitis.

Aged↗
PubMed2006

Review on the value of graduated elastic compression stockings after deep vein thrombosis.

Graduated elastic compression stockings (GECS) are commonly used in the primary prevention of deep vein thrombosis (DVT); however, their role in preventing recurrent DVT and also post-thrombotic syndrome is less well established. The aim of this review was to investigate the effect of GECS after DVT. A literature search was performed by two independent searchers in order to identify randomised controlled trials on the effect of GECS in preventing recurrent DVT and post-thrombotic syndrome. Four randomised trials, including 537 patients, were identified. Two of the studies demonstrated that below-knee GECS significantly reduced post-thrombotic syndrome during follow-up, while a smaller study showed equivocal results. GECS reduced the incidence of post-thrombotic syndrome from 54% to 25.2% [relative risk (RR) 0.47, 95% confidence interval (CI) 0.36-0.61] with the number needed to treat (NNT) being 4 (95% CI 2.7-5.0). The rate of recurrent asymptomatic DVT was also significantly reduced by GECS (RR 0.20, 95% CI 0.06-0.64; NNT 5); the reduction in symptomatic DVT was not significant (RR 0.79, 95% CI 0.50-1.26; NNT 34). In conclusion, there is level Ia evidence to suggest that GECS can significantly reduce the incidence of post-thrombotic syndrome (PTS) after DVT, and therefore these should be routinely prescribed. The evidence for recurrent DVT is less conclusive. Further research is needed towards standardising PTS diagnostic criteria and evaluating more effective preventive measures after DVT.

Bandages↗
PubMed2005

The efficacy of a new portable sequential compression device (SCD Express) in preventing venous stasis.

OBJECTIVE: It has been previously shown that the SCD Response Compression System, by sensing the postcompression refill time of the lower limbs, delivers more compression cycles over time, resulting in as much as a 76% increase in the total volume of blood expelled per hour. Extended indications for pneumatic compression have necessitated the introduction of portable devices. The aim of our study was to test the hemodynamic effectiveness of a new portable sequential compression system (the SCD Express), which has the ability to detect the individual refill time of the two lower limbs separately. METHODS: This was an open, controlled trial with 30 normal volunteers. The new SCD Express was compared with the SCD Response Compression System in the supine and semirecumbent positions. The refilling time sensed by the device was compared with that determined from velocity recordings of the superficial femoral vein using duplex ultrasonography. Baseline and augmented flow velocity and volume flow, including the total volume of blood expelled per hour during compression with the SCD Express, were compared with those produced by the SCD Response compression system in the same volunteers and positions. RESULTS: Both devices significantly increased venous flow velocity as much as 2.26 times baseline in supine position and 2.67 times baseline in semirecumbent position (all P < .001). There was a linear relationship between duplex ultrasonography-derived refill time and the SCD Express-derived refill time in both the supine (r = 0.39, P = .03) and semirecumbent (r = 0.71, P < .001) positions but not with the SCD Response. Refill time measured by the SCD Express device was significantly shorter and the cycle rate higher in comparison with the SCD Response in both positions. The single-cycle flow velocity and volume flow parameters generated by the two devices were similar in both positions. However, median (interquartile range) total volume of blood expelled per hour was slightly higher with the SCD Express device in the supine position (7206 mL/h [range, 5042-8437] vs 6712 mL/h [4941-10,676]; P = .85) and semirecumbent position (4588 mL/h [range, 3721-6252] vs 4262 mL/h [3520-5831]; P = .22). Peak volume of blood expelled per hour by the SCD Express device in the semirecumbent position was significantly increased by 10% in comparison with the SCD Response (P = .03). CONCLUSIONS: Flow velocity and volume flow enhancement by the SCD Response and SCD Express were essentially similar. The latter, a portable device with optional battery power that detects the individual refill time of the lower limbs separately, is anticipated to be associated with improved overall compliance and therefore optimized thromboprophylaxis. Studies testing its potential for improved efficacy in preventing deep vein thrombosis are justified.

Adolescent↗
PubMed2003

Validation of the new venous severity scoring system in varicose vein surgery.

OBJECTIVES: We performed this observational study to validate the three components of a new venous severity scoring (VSS) system, ie, venous clinical severity score (VCSS), venous segmental disease score (VSDS), and venous disability score (VDS), and to evaluate VCSS, VDS, and CEAP clinical class and score in quantifying outcome of varicose vein surgery. Patients and methods The study included 45 patients who underwent superficial venous surgery in 48 legs with primary varicose veins. Venous color duplex scanning, clinical examination, and a questionnaire were used preoperatively and at 6 weeks and 6 months postoperatively to assign VSS and CEAP clinical class and score. RESULTS: CEAP clinical score, VCSS, and VDS demonstrated a linear association with CEAP clinical class (P <.001, P <.001, P =.002, respectively). Good correlation among all severity scores was found, particularly between CEAP clinical score and VCSS (r = 0.94; P <.001). CEAP clinical score was also highly correlated with CEAP clinical class (r = 0.84; P <.001) and VDS (r = 0.70; P <.001). Similarly, VCSS correlated with CEAP clinical class (r = 0.83; P <.001) and also VDS (r = 0.72; P <.001). The anatomic severity marker VSDS demonstrated a weak correlation with clinical severity indicators VCSS (r = 0.29; P =.048) and VDS (r = 0.31; P =.03) but not with age, gender, or CEAP clinical class and score. Six months after surgery the median (interquartile range) percent change in VCSS (73%; range, 50%-100%) and CEAP clinical score (70%; range, 50%-100%) were both significantly greater (P <.001) than the corresponding change in CEAP clinical class (17%; range, 0%-50%). In legs with high VDS at baseline, median (interquartile range) percent change in VDS was 100% (range, 50%-100%), significantly greater (P <.001) than the corresponding change in CEAP clinical class (0%; range, 0%-17%). CONCLUSIONS: Venous severity scores are significantly higher in advanced venous disease, demonstrating correlation with anatomic extent. Both venous clinical severity scores, VCSS and CEAP clinical score, are equally sensitive and significantly better for measuring changes in response to superficial venous surgery than is the already in use CEAP clinical class. VDS demonstrated comparable and even better performance. Although the assignment of CEAP clinical class might be adequate for daily clinical purposes, venous severity scoring systems should be used in clinical studies to quantify venous outcome.

Adult↗
PubMed2002

Ambulatory venous pressure measurements: new parameters derived from a mathematic hemodynamic model.

PURPOSE: The mechanism of venous pressure decrease during exercise still remains unclear. To explore the components involved with the regulation of ambulatory venous pressure, we reinvestigated the pattern of pressure decrease during tiptoe exercise with a newly developed mathematic model. METHODS: Seventeen healthy limbs of 16 volunteers (normal group) and 35 limbs of 33 patients with signs and symptoms of chronic venous insufficiency were studied. Seventeen limbs had superficial venous incompetence (SVI), and 18 showed deep venous incompetence with or without concomitant superficial venous reflux. All subjects were examined with ambulatory venous pressure measurements. As parameters obtained from serial phasic changes in pressure during tiptoe movements, the pressure reduction fraction per step (decreasing component) and the pressure increase per step (increasing component) were calculated with application of the mathematic hemodynamic model and assessed comparatively in the three groups with different types of reflux (normal, SVI, and deep venous incompetence group). RESULTS: The pressure increase per step was significantly different in each of the three groups (P <.0001, with analysis of variance), whereas no apparent difference was seen in the mean pressure reduction fraction per step among the groups. With addition of the inflation of ankle cuff, the value of pressure increase in limbs with SVI was significantly reduced (P =.0004, with Wilcoxon signed rank test), although no changes were seen in the pressure reduction fraction in each group. CONCLUSION: Our results indicate that the pressure reduction fraction, representing calf muscle pump function, is independent of the existence or site of valve incompetence. On the other hand, the pressure increase, corresponding to the degree of reflux during exercise, correlates strongly with the severity of venous insufficiency. The theoretic model can separate the two components responsible for ambulatory venous pressure changes, calf muscle pump function and venous reflux, and provide better understanding of venous hemodynamics.

Blood Pressure Monitoring, Ambulatory↗
PubMed2002

S-18886 Servier.

S-18886, the active isomer of S-18204, is a thromboxane A2 receptor antagonist with a long duration of action. The compound is under development by Servier for the potential treatment of cardiovascular diseases [269611]. By 2000, a clinical trial had been carried out in patients with coronary artery disease [389458]; advanced clinical trials were ongoing in August 2001 [420310].

Animals↗
PubMedDate not supplied

Ultrasound plaque characterisation, genetic markers and risks.

The arterial wall changes detected by ultrasound are the end result of all risk factors (exogenous, endogenous and genetic) known and unknown and are better predictors of risk than any combination of conventional risk factors. However, ultrasound cannot be used in people younger than 45 because characteristic changes occur after this age. Nevertheless, it can be used in individuals over 45 to identify the genetic risk factors associated with atherosclerosis. The identification of genetic factors will subsequently provide a means of identifying individuals at risk at an early age, even childhood. In addition, knowledge of the genetic abnormalities associated with increased risk in a particular individual will provide a means of targeting prophylactic therapy.

Arteriosclerosis↗
PubMedDate not supplied

Effect of image normalization on carotid plaque classification and the risk of ipsilateral hemispheric ischemic events: results from the asymptomatic carotid stenosis and risk of stroke study.

The aim of this study was to determine the effect of image normalization on plaque classification and the risk of ipsilateral ischemic neurologic events in patients with asymptomatic carotid stenosis. The first 1,115 patients recruited to the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study with a follow-up of 6 to 84 months (mean 37.1 months) were included in this study. Duplex ultrasonography was used for grading the degree of internal carotid artery stenosis and for plaque characterization (types 1-5), which was performed before and after image normalization. One hundred sixteen ipsilateral ischemic hemispheric events occurred. Image normalization resulted in 60% of plaques being reclassified. Before image normalization, a high event rate was associated with all types of plaque. After image normalization, 109 (94%) of the events occurred in patients with plaque types 1 to 3. For patients with European Carotid Stenosis Trial (ECST) 70 to 99% diameter stenosis (equivalent to North American Symptomatic Carotid Endarterectomy Trial [NASCET] 50-99%) with plaque types 1 to 3, the cumulative stroke rate was 14% at 7 years (2% per year), and for patients with plaque types 4 and 5, the cumulative stroke rate was 0.9% at 7 years (0.14% per year). The results suggest that asymptomatic patients with plaque types 4 and 5 classified as such after image normalization are at low risk irrespective of the degree of stenosis.

Carotid Artery, Internal↗