Surgery – Instruments – Means for concretion removal
Patent
1993-02-16
1994-07-19
Pellegrino, Stephen C.
Surgery
Instruments
Means for concretion removal
606127, 606113, A61B 1722
Patent
active
053304845
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for fragmentation of thrombi, comprising an external catheter, an internal catheter passed through the external catheter, a torsion-resistant flexible shaft journalled in the internal catheter, a fast rotating drive means for said shaft at the proximal end of the external catheter and an action body connected with the shaft to be unturnable thereto.
Such devices are known in various designs and serve for percutaneous recanalization of blood vessels. An action body arranged at the distal end of the catheter of devices, e.g. in the form of a twin-bladed propeller driven by a shaft journalled in the interior of the catheter serve to fragment thrombi in the blood vessel thereby to restore a free flow passage for the blood through the vessel.
According to their mode of operation the prior devices may be divided into two groups:
In devices of a first group, such as from EP-Al-0367982, fragmentation of the thrombi is performed by means of a propeller-like action body with cutting blades in the area of the catheter tip, accompanied by simultaneous transcatheteral evacuation of the thrombi fragments.
A significant disadvantages of such devices operating with transcatheteral aspiration results from the tendency of the catheter tip to be displaced by insufficiently fragmented thrombi, whereby a further determined processing of the thrombi will be prevented. In particular, this disadvantage has a serious effect in case of fibrin-containing and/or large quantities of thrombi.
In devices of a second group, such as known from U.S. Pat. No. 4,747,821 the fragmentation of thrombi is performed by means of an action body arranged in the area of the catheter tip and being caused to rotate at up to 100,000 r.p.m. The high rotational speed of the action body causes thrombi to be sucked into the action volume and results in a through fragmentation of the thrombi.
A significant disadvantage of these devices operating without transcatheteral aspiration follows from the risk of damage to the walls of the vessel by the action body in spite of a to a large extent curved external shape of the latter.
To counteract the risk of damaging the walls of the vessel, a device has been suggested in the published international patent application WO-A-88/00243 in which a rigid metallic envelope having an opening at one end as well as several radial openings distributed over the circumference surrounds the action body. Even if the rigid metallic envelope eliminates the risk of direct contact and thereby damage to the walls of the vessel by the action body it is a disadvantage that the openings of the envelope easily get blocked by thrombi, in particular as a result of the fibrin fibres contained therein. Moreover, the operation of this device is affected by the fact that the narrow annular clearance between the inner side of the rigid envelope and the outer side of the action body will be further narrowed by fibrin fibres winding around the action body. In addition, the narrow enclosure of the action body influences the transfer of the high rotational velocity to the surrounding liquid. Thereby, the vortex formation and suction effect resulting therefrom will be very limited.
It is an object of the invention to provide a device of the above-mentioned kind of such a design that while maintaining the operation in respect of fragmentation of thrombi into small particles by means of a fast rotating action body, the risk of damages to the vessel is eliminated without any need to enclose the action body in a rigid, protective envelope which affects the suction action on the thrombus.
To accomplish this, a fragmentation device according to the invention is characterized in that the internal catheter is composed of a proximal and a distal part, between which the action body is arranged with the shaft of the action body journalled in both parts of the internal catheter, the action body being concentrically surrounded by a resiliently deformable grid body, comprising legs through which the two parts of the internal cathete
REFERENCES:
patent: 4811735 (1989-03-01), Nash et al.
Gunther Rolf W.
Schmitz-Rode Thomas
Dawson Glenn
Godlewski Richard J.
Pellegrino Stephen C.
William Cook Europe A/S
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