Enforced guiding catheter

The claimed invention refers to medical technologies and can be applied in endovascular surgery and in interventional cardiology, mainly for recanalization of chronically occluded coronary arteries.

Delivery of instruments or a pharmaceutical composition immediately to a place of a vascular disruption by application of guiding catheters is commonly known in endovascular surgeries, including interventional cardiology. The guiding catheter, as a rule, is executed in the form of an elastic tube made of a smooth polymer and radiopaque stuff, usually, reinforced to ensure the necessary flexibility for minimization of vascular walls trauma. After a guiding catheter achieves a place of prospective operation the working instrument or a medical product is delivered through the inner channel of the catheter to the place of operation (see patent RU2203104 [I]). The position of the distal end of a guiding catheter is usually controlled by means of observation of its contrast level or of its radiopaque labels. It should be mentioned, however, that the outer diameter of a guiding catheter is, as a rule, essentially smaller, than the inner diameter of the bloodvessel into which the catheter is inserted. This enables elimination of possibility of occlusion of the blood-vessel and of discontinuation of the blood flow; however, a drawback of such design consists in insufficient fixation of a guiding catheter in a lumens of the arterial segment, seriously complicating or restricting efficiency of the operation which is carried out by instruments introduced through the catheter. Used in intervention cardiology in the course of a balloon angioplasty and coronary stenting, the guiding catheters are fixed in lumens of coronary arteries due to the special flexures, and also due to introduction beyond the arterial ostium, which can result in high risk of a mechanical trauma of an

arterial wall, its dissection and thrombosis. Rigid bracing of a guiding catheter in lumens of an artery constitutes a necessary condition for conducting a recanalization of a chronic arterial occlusion as the inserted instruments should overcome resistance in the occluded segment. There are several methods of improving bracing of a guiding catheter: 1) insertion of an additional coronary wire; 2) insertion of a balloon catheter in an artery at the moment of recanalization efforts by a special wire; 3) insertion of an additional wire in a lateral branch of an artery in a position more proximal than an occlusion area, insertion of a balloon catheter along this wire and inflation into the side brunch, wherein the said balloon catheter serves as an "anchor". At the same time, the above methods do not solve, to full extent, the problem of bracing of a guiding catheter in an arterial lumens, an anatomical diversification of arteries constitution do not always allow to implement the said methods, they necessitate the use of additional tools and are, in many cases, technically impossible. Furthermore, it is necessary to note, that in spite of introduction, in the clinical practice, of new coronary wires with increased rigidity, and also various apparatus methods of a recanalization of chronic arterial occlusions (eximer laser, SafeCross system, etc.), fixation of a guiding catheter in an arterial lumens remains the major and still unsolved aspect of endovascular recanalization of chronic arterial occlusions.

Devices for bracing (or «anchoring») the distal end of a guiding catheter are known, for example, from the US patent 5,885,238 [2] in which the system of endovascular blocking of a coronary artery lumens by means of an inflatable balloon at the distal end of the catheter, is described. In the said system the catheter is not a guiding catheter, but only provides «a gag», blanking coronary arteries, i.e. a different problem is solved; however, the principle of an inflatable balloon is applicable to bracing (fixation) the distal end of a guiding balloon.

Such solution is known, for example, from the US patent 5,000,743 [3], and, being most similar to the claimed invention, is chosen as the prototype.

The patent describes a system consisting of two catheters, i.e. a guiding catheter and a balloon dilatation catheter. The guiding catheter is supplied, at the distal end, by the inflatable balloon located around the catheter, which, in an inflated state provides certain degree of fixation of the position of the distal end of the guiding catheter. Such fixation ensures increased accuracy of introduction of a working part of dilatation catheter in a blood vessel.

The main drawback of the above solution consists in practically full closure of a blood vessel by the inflated balloon, though the authors have tried to solve this problem, at least in part, by disposing holes in the wall of the guiding catheter not far from the balloon. Such solution, however, sharply impedes the blood flow in the blood vessel and, thus, have restrictions as to the operation duration. Besides, as the guiding catheter is made, usually, of a stuff providing a sufficient slip in the blood vessel, the balloon with the same surface will be reliable fixed only at rather high inner pressure which can result in a trauma of the blood vessel. When the tools introduced through such catheter face resistance, the catheter can slip out of the lumens of an artery.

The problem to be solved by the claimed invention consists in providing a reliable fixation of the distal end of a guiding catheter in a blood vessel with the minimal trauma of vascular walls, having maintained the sufficient channels for blood flow. The technical result consists in ensuring stability of bracing a catheter at preserving free blood circulation, which results in lower homodynamic complications during operation, and also in better chance of success in endovascular recanalization of chronically occluded arteries.

The essence of the claimed invention consists in that a guiding catheter for endovascular recanalization of chronically occluded coronary arteries, comprises a polymeric tube provided with a main channel capable of introducing a dilatation balloon catheter or a stent, and an auxiliary channel capable of building an overpressure in an elastic balloon located on the distal end of the catheter; the elastic balloon consists of, at least, one capacity located on the surface of the polymeric tube, which capacity is communicating with the auxiliary channel and is supplied, on its outer surface with, at least, one element of additional fixation. For practical implementation of the claimed invention it is expedient, that the length of each capacity was in the range of 2 to 30 mm, and the cross- section size was in the range of 0.5 to 5 mm. If there is more than one capacity they are mainly located radially and symmetrically regarding the longitudinal axis of the catheter. The perimeter of a working surface of a balloon capacity on the surface of the polymeric tube also does not exceed, preferably, half of the perimeter of the cross section of the polymeric tube.

For achievement of the best traction of the inflated balloon with blood vessel walls, the element of the additional fixation is executed in the form of, at least, one fixing prominence, which prominence can be, preferably, executed of the same stuff, as an elastic balloon.

It makes sense, that the fixating prominence is executed, preferably, in the form of a hemisphere.

It makes sense, that if the number of capacities is more than one, the capacities are located symmetrically regarding the longitudinal axis of the polymeric tube.

Overpressure in an elastic balloon is provided by controlled introduction of radiopaque substance that increases accuracy of localization of

the distal end of a guiding catheter.

Besides, an overpressure in the capacities of an elastic balloon is provided through taps to the auxiliary channel.

It is preferable, that at the distal end of a catheter the holes have been made for communication between the main channel and a blood flow in an aorta.

The proximal of a catheter can have the Y-adapter for injection, through one input of the basic channel, of radiopaque substance, or insertion of instruments, and the second input is connected to a high pressure syringe with capability of inflating the elastic balloon comprising, at least, one capacity.

Further the essence of the invention is illustrated by drawings. Fig. 1 shows a general diagram of the claimed catheter where 3 is the catheter, 11 is the Y-shaped proximal end, 5 is the distal end with the capacities of balloon.

Figs. 2.1, 2.2 show catheter 3 located in an ostium of the coronal artery 2 branching from aorta 1, and the mechanism of its fixation due to capacities of balloon 5 with a fixating prominence (projection) 9.

Figs. 3.1, 3.2 show the cross section of artery 2 in a place of location of a guiding catheter before inflation of capacities of balloon 5 which capacities are supplied by fixating prominences, and after inflation of balloon 5.

The cross section shown on Fig. 3.2, allows seeing, in this example, the presence of three capacities of balloon 5, which provides much more opportunities for maintenance of practically normal blood flow. It is necessary to note, that the holes described in the prototype, are kept intact in the claimed design, however, they do not play an essential role in maintenance of the blood flow at presence of wider channels shaped between

capacities of the balloon and the arterial walls.

Fig. 4 shows the longitudinal section of guiding catheter 3, where the channel inside the walls of the catheter is schematically presented, leading to capacity of balloon 5. Through this channel connected with Y-shaped proximal end of the catheter, the capacity of balloon 5 is supplied by a contrast agent inflating the capacity of the balloon, which results in extension of the balloon and the guiding catheter is fixed in an artery by means of prominences 9.

Diagrams on Fig. 5 (5.1 to 5.6) demonstrate the operation of the claimed method in the process of endovascular recanalization of an occlusion of a coronary artery.

- guiding catheter 3 is introduced into an ostium of the blood vessel 2;

- in case of mechanical difficulties at guiding a coronary conductor 6 through an atherosclerotic occlusion 4, the capacities of the balloon, at the distal end of a guiding catheter, are inflated by pumping the contrast agent, under pressure, in the capacities of the balloon through the auxiliary channel, and, due to close contact of the balloon walls and fixating prominences of the balloon and the arterial walls, the catheter is fixed in blood vessel 5 (Fig. 5.2);

- further, the capacities of the balloon can be deflated (Fig. 5.3) and inflated in case of difficulty in guiding balloon catheter 7 through occlusion area 4 (Fig. 5.4);

- further, a routine balloon angioplasty of artery 2 in the occlusion area 4 is performed by means of balloon catheter 7 (Fig. 5.5) and, afterwards, an implantation of coronary stent 8 can be performed (Fig. 5.6).