Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Patent
1998-08-31
2000-01-11
Jaworski, Francis J.
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
600472, A61B 812
Patent
active
060130334
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a catheter for echographic imaging within a cavity.
BACKGROUND
It is known that the detection and the evaluation of the severity of certain diseases are based on the analysis of echographic images. Thus, intravascular ultrasound imaging has been developed for characterizing atheromatous lesions in man. The resolution which can be obtained with ultrasound depends in fact on the frequency used, and the higher this frequency, the better the resolution. However, the attenuation which the ultrasound beam suffers increases with the frequency, and the depth of penetration of the beam diminishes considerably. An image with very good resolution at high frequency can therefore only be obtained by the intravascular route.
The treatment of the lesions due to the presence of atheromatous plaque in the coronary arteries involves recourse to two distinct invasive techniques: surgery and catheter intervention (balloon angioplasty or laser). The use of catheterized instruments represents a comfortable alternative. However, surgery proves necessary when the lesions are serious, that is to say when they are in an advanced state. In this case, the surgical interventions consist in replacing the stenosed portion of the coronary artery with part of another artery, either by removal and grafting, which creates a bypass round the zone, or by using another artery to irrigate the heart.
The catheters are used for the interventions employing the balloon angioplasty technique. In this technique, a catheter measuring about 1.5 meters in length and 1 mm in diameter is introduced percutaneously into the femoral artery and is advanced to the coronary artery by progressing through the arterial network. The probe is guided with the aid of a guide wire which may or may not be integral with the catheter and whose end is curved in order to avoid perforations during the manoeuvres needed for advancing and orienting the catheter. This progress is monitored by an external imaging technique, which makes the positioning easier and safer. The therapy can also be based on the abrasion of the atheromatous plaque by laser or mini-scalpel, the guiding of which is based on the same principle as for the angioplasty catheters.
The criteria for the choice of using one or other of the methods mentioned hereinabove are empirical. They take account of a priori knowledge of the structure of the plaque and of the extent of its thickness and length. Despite the preference for angioplasty, because of its greater simplicity, the two methods nevertheless entail substantial risks.
The manoeuvrability of the catheter, the simplification of the intervention procedures, the increase in the resolution cell and the awareness of the position of the distal end of the catheter are the key points in the development of this therapeutic control technique.
Intracoronary echography is distinguished by the small dimensions of the elements to be investigated and of the routes for gaining access to these. This is reflected in a quite particular specification for the design of the catheters, the piezoelectric elements, the elements permitting scanning, and the instruments for treating the stenoses.
Furthermore, the aim of quantitative echography is the complete exploitation of the echographic signal and the extraction of the quantitative parameters aiding in the diagnosis and providing additional information compared to the traditional echographic image. Thus, the methods for characterizing tissues by ultrasound permit estimation of the quantitative parameters on the basis of the echographic signal or echographic image. These methods also demand specific characteristics as regards the systems for obtaining the echographic signals or images.
Thus, the cable of the catheter, the total length of which is about 1.50 meters, has a proximal part which is sufficiently rigid to permit guiding, and a more flexible distal part which has an overall diameter of 1 to 2 mm and a length of 2 to 15 cm. The distal end is made up of a capsul
REFERENCES:
patent: 5367878 (1994-11-01), Muntz et al.
patent: 5606975 (1997-03-01), Liang et al.
patent: 5779643 (1998-07-01), Lum et al.
Allano Sylvain
Berger Genevieve
Bovo Nicolas
Dufour Isabelle
Grandchamp Jean-Paul
Behr Esq. Omri M.
Centre National de la Recherche Scientifique
Jaworski Francis J.
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