Preliminary report on a new concept stent prototype designed for venous implant

Venous obstruction at iliocaval level in both forms, primary and secondary, is a significant cause of severe chronic venous insufficiency. A new therapeutic approach to this pathology emerged with the introduction of stenting procedures that proved effective, leading to good long-term results. However, at present, the majority of implanted stents have been designed for arterial implant and this can pose a limit in particular districts. The purpose of this preliminary acute study was to verify the deliverability and safety of a new stent specially designed for venous-vessel implant. We assess the safety and deliverability of two braided, self-expanding, nickel–titanium stents (Jotec GmbH, Hechingen, Germany) specially designed for endovascular implant in veins. The two stents, despite being based on the same concept, have a different design: stent A presents a proximal tapering shape specially designed to reduce migration, while stent B does not. Both of them are enlarged at their distal extremity and present variable radial force the length of the stent itself, the said force becoming very high in the intermediate segment. Stents were implanted in the internal jugular vein of a sheep, showing optimal deliverability. The completion venography showed the migration of stent B into the right atrium. Stent A maintained its location, confirmed by intravascular ultrasound examination. No scaffolding effect was detected and an adequate adherence and adaptability to the vein wall was obtained. In conclusions, the stent A design matches the characteristics required by vein implants. Stability is achieved even where difficult anatomical conditions apply, such as in the jugular vein. Deployment is easy and precise in a given landing zone. Radial resistive force is very high, as required in specific vein districts, but is also associated with good flexibility. Following this preliminary acute report, further studies are required.

Quantitation of reflux and outflow obstruction in patients with CVD and correlation with clinical severity

AIM

Chronic venous disease (CVD) is the result of venous reflux, obstruction or a combination of both. So far, attempts to correlate venous hemodynamic measurements with symptoms and signs of CVD have produced poor to moderate results, probably because of lack of methods to quantitate obstruction and combine measurements of reflux and obstruction. Our hypothesis is that the combination of quantitative measurements of (a) overall reflux (superficial and deep) and (b) overall outflow resistance i.e. including the collateral circulation would provide a hemodynamic index that should be related to the severity of the disease.

METHODS

Twenty-five limbs with chronic venous disease and 1 limb from a healthy volunteer (VCSS 0-13) were studied. The clinical CEAP classification was C0 in one limb, C1 in 2 limbs, C2 in 10 limbs, C3 in 3 limbs, C4 in 1 limb, C5 in 6 limbs and C6 in 3 limbs. Air-plethysmography was used to measure reflux (VFI in mL/s) when the subject changed position from horizontal to standing. Subsequently, with the subject horizontal and the foot elevated 15 cm, simultaneous recordings of pressure and volume were made on release of a proximal thigh cuff inflated to 70 mmHg. Pressure change was recorded with a needle in the foot and volume change with air-plethysmography. Flow (Q in mL/min) was calculated at intervals of 0.1 seconds from tangents on the volume outflow curve. Outflow resistance (R) was calculated at 0.1 second intervals by dividing pressure by the corresponding flow (R=P/Q). R increased markedly at pressures lower than 25 mmHg due to decrease in vein cross-sectional area, so resistance at 25 mmHg (R25) was used in this study.

RESULTS

In a multivariable linear regression analysis with VCSS as the dependent variable, both VFI and R25 were independent predictors (P<0.001). Using the constant (0.595) and regression coefficients, the regression equation provided a Hemodynamic Index (HI) or estimated VCSS=0.595 + (VFI x 0.41) + (R25 x 98). Thus, HI could be calculated for every patient by substituting VFI and R25 in the equation. HI or calculated VCSS was linearly related to the observed VCSS (r=0.86).

CONCLUSION

The results indicate that the combination of quantitative measurements of reflux and outflow resistance provide a hemodynamic index which is linearly related to the VCSS. These findings need to be confirmed in larger series.

The hypothesis of patho-physiological correlation between chronic cerebrospinal venous insufficiency and multiple sclerosis: rationale of treatment

BACKGROUND

The possible role of the venous system in the pathogenesis of chronic neurodegenerative diseases has been hypothesized for decades. Quite recently, the description of a venous condition defined as chronic cerebrospinal venous insufficiency (CCSVI) and its strong association with multiple sclerosis (MS) has brought back the attention of the scientific community to the hypothesis of an aetiological or concomitant role of an altered venous function in the occurrence of this pathology. CCSVI is identified by sonographic criteria, thus the indication for its possible treatment is based on ultrasound findings.

METHOD

We retrospectively examined 167 consecutive patients affected by clinically defined MS and CCSVI, identified by ultrasound assessment by the presence of at least two sonographic criteria. Ultrasonographic diagnosis of CCSVI was then integrated by venography and intravascular ultrasound examination (in 43 patients). Patients were all submitted to endovascular procedure (venoplasty).

RESULTS

In 37% of cases there was no correspondence between the preoperative ultrasound assessment and the venographic findings. In the event of incongruity between venography and sonography, the intravascular ultrasound examination investigation, when performed, confirmed ultrasound findings in 42% of cases and venography results in 58%. At one month in 12% of cases ultrasound assessment showed the persistence of altered flux. In 67% of cases patients reported subjective amelioration, regarding non-specific symptoms.

CONCLUSION

The pathophysiology of CCSVI is yet to be defined. The superior cava venous system is highly complex in terms of anatomy and possible anomalies, as well as its haemodynamic mechanisms. Further studies are required to define the parameters of diagnosis and treatment of CCSVI.

A French-Italian survey on the prevalence of isolated varices (C2) and complicated varices (C2+). Results of a multi-centre study conducted by the SFA and the SFP under the auspices of the European Venous Forum

AIM

The advanced CEAP classification allows one to differentiate between isolated varicose veins (C2) and complicated varicose veins (C2, 3 - C2, 3, 4 - C2, 4 or C2, 3, 4, 5 etc) named (C2+).

METHODS

The main objective of this study was to identify when using the advanced classification the prevalence of isolated varicose veins (C2) and complicated varicose veins (C2+) among patients consulting vascular specialists and to compare their symptomatic status and the data issued from the advanced CEAP including also the headings, Anatomy (A), Etiology (E) and Pathophysiology (P).

RESULTS

171 patients were evaluated, 100 in France and 71 in Italy. The prevalence of C2 and C2+ was the same in both countries: 64.4% in France and 63.3% in Italy. Also no difference was found in the prevalence of other descriptors: etiology, anatomy or pathophysiology. The time to complete the advanced form was less than 5 minutes for 65% of the investigators.

CONCLUSION

The advanced CEAP is easy to use in daily pratice. We have the same prevalence of patients in France and in Italy, who consulted for isolated varicose veins or associated with other signs of chronic venous disorders.

Effects of eccentric compression by a crossed-tape technique after endovenous laser ablation of the great saphenous vein: a randomized study

OBJECTIVES

To evaluate the effect of eccentric compression applied by a new crossed-tape technique on procedure-related pain occurrence after endovenous laser ablation (ELA) of the great saphenous vein (GSV).

METHODS

From April 2005 to June 2006, 200 consecutive ELA procedures were randomized to receive (group A: 100) or not (group B: 100) an eccentric compression applied in the medial aspect of the thigh. Patients were scheduled for a seven-day examination to assess the level of pain experienced. Pain intensity was measured using a visual analogue scale giving a numerical grade from 0 (no pain) to 10 (worst pain ever).

RESULTS

The intensity of postoperative pain was significantly reduced (P < 0.001) in the eccentric compression group as compared with the non-compression one.

CONCLUSIONS

This technique of eccentric compression greatly reduces the intensity of postoperative pain after ELA of the GSV.

Acoustic communication in two freshwater gobies: ambient noise and short-range propagation in shallow streams

Noise is an important theoretical constraint on the evolution of signal form and sensory performance. In order to determine environmental constraints on the communication of two freshwater gobies Padogobius martensii and Gobius nigricans, numerous noise spectra were measured from quiet areas and ones adjacent to waterfalls and rapids in two shallow stony streams. Propagation of goby sounds and waterfall noise was also measured. A quiet window around 100 Hz is present in many noise spectra from noisy locations. The window lies between two noise sources, a low-frequency one attributed to turbulence, and a high-frequency one (200-500 Hz) attributed to bubble noise from water breaking the surface. Ambient noise from a waterfall (frequencies below 1 kHz) attenuates as much as 30 dB between 1 and 2 m, after which values are variable without further attenuation (i.e., buried in the noise floor). Similarly, courtship sounds of P. martensii attenuate as much as 30 dB between 5 and 50 cm. Since gobies are known to court in noisy as well as quiet locations in these streams, their acoustic communication system (sounds and auditory system) must be able to cope with short-range propagation dictated by shallow depths and ambient noise in noisy locations.

Acoustic communication in two freshwater gobies: the relationship between ambient noise, hearing thresholds and sound spectrum

Two freshwater gobies Padogobius martensii and Gobius nigricans live in shallow (5-70 cm) stony streams, and males of both species produce courtship sounds. A previous study demonstrated high noise levels near waterfalls, a quiet window in the noise around 100 Hz at noisy locations, and extremely short-range propagation of noise and goby signals. To investigate the relationship of this acoustic environment to communication, we determined audiograms for both species and measured parameters of courtship sounds produced in the streams. We also deflated the swimbladder in P. martensii to determine its effect on frequency utilization in sound production and hearing. Both species are maximally sensitive at 100 Hz and produce low-frequency sounds with main energy from 70 to 100-150 Hz. Swimbladder deflation does not affect auditory threshold or dominant frequency of courtship sounds and has no or minor effects on sound amplitude. Therefore, both species utilize frequencies for hearing and sound production that fall within the low-frequency quiet region, and the equivalent relationship between auditory sensitivity and maximum ambient noise levels in both species further suggests that ambient noise shapes hearing sensitivity.

Reliability of antagonistic arch impression in dental prostheses: clinical evaluation of different preimpression preparation procedures

This study compared the influence of different methods of preimpression preparation on the quality of occlusal reproduction in irreversible hydrocolloid impressions. A total of 30 impressions of the lower dental arch of a patient were made with five different preimpression preparation procedures. Stone casts were made and analyzed. Critical comparison showed that the preimpression preparation influenced the quality of the occlusal surface of the cast. Fingerpainting the occlusal surface with fluid hydrocolloid before positioning the loaded impression tray, associated with use of a saliva ejector, reduced the incidence of macroscopic defects on the occlusal surface of the impressions.

[Materials for dies in fixed prosthesis: a comparative in-vitro analysis of their detail-reproducing capacity and of their surface quality]

The authors examine the detail reproduction capacity and surface roughness of 11 commercially available materials [6 plasters (stones?), 2 epoxy resins and 3 polyurethane resins] indicated for the construction of working models with individually extractable dies. The study was performed in vitro according to the method outlined by the ADA in specification no. 19 relating to materials for elastomeric imprints. This specification describes the use of a steel test-block with which it is possible to prepare a master imprint in polyvinylsiloxane. This imprint allows the grooves of the test-block to be reproduced in the form of angular crest which represent the details to be reproduced. Both the master imprint and the samples to be tested were prepared according to the manufactures instructions. The study was performed in three stages: macroscopic analysis, microscopic analysis, profilometric analysis. The macroscopic analysis did not show any differences between the different materials tested. The microscopic analysis showed that when enlarged 40 times the resins revealed a smoother surface than the plasters. The surface quality of plasters was improved by using a hardening solution recommended by the manufacturer as an alternative to water, or by using spacer paint. The plaster materials gave excellent angular definition contrary to the epoxy and polyurethane resins. The use, where advised, of the hardening solution as an alternative to water did not alter this parameter. The electronic profilometer used for the profilometric analysis comprised a diamond sensor which, when run along the surface, recorded all roughness, translating it into chart form.(ABSTRACT TRUNCATED AT 250 WORDS)