RU2764189C1 - Stent graft for treating aneurysms and aortic dissection - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine, in particular, to endoprosthetics, and can be applied for use in endovascular and cardiovascular surgery in treatment of aneurysms and aortic dissection (AD). The stent graft (SG) for treating aneurysms and aortic dissection consists of an outer element and an inner element made of a woven material and located inside the outer element, and the proximal and distal ends of the SG are marked with radiocontrast markers. The outer element is made in the form of a self-expanding mesh with a diameter of 20 to 50 mm and a length of 150 to 200 mm, containing diamond-shaped cells configured for changing the configuration thereof in accordance with the diameter of the aorta. The woven material of the inner element attached to the outer element by interrupted sutures from a non-absorbable surgical thread constitutes a PET (polyethylene terephthalate) sheet with a permeability for blood with heparin from 50 to 150 ml/cm²/min at a pressure of 120 mm Hg. with the possibility of controlled preservation of the endoleak inside the SG. The method for installing the above SG in endoprosthetics of aneurysms and aortic dissection is characterised by the fact that said SG is delivered to the installation site in the aorta, then a guide with a guiding catheter is passed through the lumen of the SG to the mouth of the aortic branch, the inner element of the SG is perforated with a guide opposite the mouth of the aortic branch through the corresponding cell of the outer element of the SG, the guiding catheter is removed, the peripheral SG is inserted into the artery on a balloon through the perforated inner element of the SG, wherein the proximal end thereof is left in the corresponding cell of the outer element of the SG, by inflating the balloon, the peripheral SG is secured in the artery, wherein the corresponding cell of the outer element of the SG is deformed by the proximal end thereof, the balloon and the guide are removed, wherein heparinisation is executed during installation of the SG and the peripheral SG, and the endoleak is preserved for the duration of installation of the SG and the peripheral SG.

EFFECT: advantages of the SG are the fact that the SG is universal and does not require a long wait for manufacture in factory conditions, thereby significantly simplifying the implantation and perforation technology, therein preventing the occurrence of such dire complications for the patient as endoleaks, and due to the controlled permeability prevents ischemia of vital organs supplied with blood from the branches of the aorta blocked by the SG.

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Description

The invention relates to medicine, more specifically to endoprosthesis, and can be used in endovascular and cardiovascular surgery in the treatment of aneurysms and aortic dissection (RA).

Cardiovascular diseases (CVD) lead in the structure of total mortality worldwide, incl. in Russia and account for 57.1%. According to the WHO, 17.5 million people die from CVD each year. This accounts for approximately 31% of all deaths in the world. 85% of these deaths are due to heart attack and/or stroke. World health statistics register a steady increase in the incidence of aortic aneurysms (AA) (especially in recent decades), and by now this pathology has ceased to be casuistry, occupying one of the leading positions among cardiovascular diseases.

In modern vascular surgery, aneurysms of the aortic arch, thoracic and abdominal aorta, as well as dissection, are a complex clinical and technical problem, since they are particularly dangerous due to the complications that often accompany these diseases and create a real danger of death or severe disability from due to the high risk of rupture.

Despite the significant risk of adverse intra- and postoperative complications, as well as a significant risk of mortality, the standard treatment for such diseases for a long time is surgical resection with the installation of a vascular prosthesis, as well as surgical repair with complete replacement of the aortic arch. Unfortunately, more than 40% of patients are considered unsuitable for such procedures due to their age and cardiopulmonary status. (Is it time for total endovascular aortic arch replacement? VEITHsymposium Bulletin July 2020). Meta-analysis by Urbanski et al. showed a median 30-day mortality of 11% among 1232 patients treated at the aortic arch, with significant variation in mortality rates (2% to 19%) that depended on center experience, patient age, prior sternotomy, and need for concomitant reconstruction . (Multicentre analysis of current strategies and outcomes in open aortic arch surgery: heterogeneity is still an issue. Eur J Cardiothorac Surg. 2016; 50(2):249-255.).

In view of this, the treatment of patients with AA and RA, despite the improvement of the surgical technique of operations, the development of new methods of anesthetic aids and cardiopulmonary bypass, the use of high-quality materials for aortic prosthetics, is an urgent problem in vascular surgery.

In this regard, at present, the technique of endovascular treatment of AA and RA is being actively introduced into clinical practice. This approach is an alternative to open surgery and a real method of choice for patients with severe comorbidities, with a high risk of intra- and postoperative complications. In many respects, this became possible due to the development of devices used in the endovascular approach - stent grafts (SG). SG is a tube of synthetic or biological material connected to a metal component that provides a support function. Modern SGs are self-expanding, their components are: a metal frame and an artificial woven coating material. Currently, several models of SG are available for the treatment of abdominal aortic aneurysm (AAA), which differ in design, number of modules, stent base and structure, thickness, porosity, methods of attaching prosthesis tissue to the stent, and the presence or absence of the possibility of active fixation of the device to the aortic wall. .

There are many requirements for SG, mainly related either to the woven component (its permeability, biocompatibility, athrombogenicity, flexibility, strength, and wear resistance) or to the frame component (the radial force developed by the component and its radial rigidity, elasticity, radiopacity, and wear resistance). In addition to the requirements for components, the design of the SG must also solve the problems posed, especially those associated with the anatomy of the aorta and its branches.

As it turned out, endovascular stenting is also characterized by the appearance of a number of specific complications, such as endoleaks (abnormal blood flow in the aneurysm cavity that persists after prosthesis implantation). In this connection, there is a leakage into the space between the prosthesis and the aneurysmal sac. As well as stent or stent graft fractures, graft displacement, iliac artery rupture, retrograde dissection, microembolization, aortoesophageal (aortoesophageal) fistula, and local complications at the injection site (eg, groin infection, lymphocele, seroma). Endolik (regardless of its type) is an undesirable phenomenon (complication), as it retains blood flow in the aneurysm cavity, which can lead to further progression of the vessel expansion and its rupture.

The most commonly used in the world for the treatment of AA are CG Endurant II, Excluder C3, Zenith and their analogues. All these SGs are modular cylindrical or conical structures made of synthetic material (dacron, polytetrafluoroethylene (PTFE)) with a metal frame of various shapes sewn to it (nitinol stent). The use of these SG data in a number of patients is limited by the peculiarities of the vascular anatomy and the type of aneurysms. In addition, for the installation of such SGs, a prerequisite is the presence of an unchanged aortic wall in the proximal and distal implantation zones for reliable fixation. In this regard, only 70% of patients with AA can be offered this type of treatment. In the remaining 30% of cases, the presence of a short aneurysm neck or its absence, involvement of large main arteries (brachiocephalic, visceral) into the aneurysmal sac is an absolute contraindication to endovascular treatment.

To eliminate these shortcomings in the treatment of AA and RA, branched SG and methods of SG fenestration during surgery began to be developed, since in surgery of aortic aneurysms, especially in the area of the thoracic aortic arch and supra- and juxta-renal sections of the abdominal aorta, it is extremely important to preserve the blood supply to vital organs. , feeding from the branches of the aorta, as well as the maximum reduction in the timing of the temporary stoppage of blood flow through these branches. Cessation of blood flow along the brachiocephalic branches of the aorta is permissible up to 10 minutes, along the visceral branches of the abdominal aorta up to 20 minutes. Since all known SGs have a blood-impermeable wall - a shell, a fenestrated prosthesis, despite the shortcomings described below, was initially recognized as the only way out of this situation. Today, this technique is an innovative technique used in the treatment of aneurysms and dissections of the arch and descending aorta. "Chimney" and other branching technologies, without gaining time to stop local blood flow along the branches of the aorta, have much worse hemodynamic parameters compared to fenestrated SGs (and, consequently, a worse prognosis for the patency of the structure, i.e., the ability to pass blood flow for a long time in sufficient volume, as well as a significant danger of endoleaks). At the same time, the use of branched and fenestrated SGs has shown the best results among existing endovascular technologies in the treatment of patients with AA and RA.

Special personalized SG models have been developed, such as fenestrated SG (Zenith Fenestrated by the American company Cook Medical LLC) and branched SG (E-xtra DESIGN ENGINEERING by the German company Jotec GmbH). The appearance of such SG fenestrated and branched with a graft by the factory method showed optimistic results, however, the technical complexity of the procedure and the high cost of consumables do not allow this technique to be introduced into wide clinical practice and, moreover, included in the provision of high-tech medical care. In this regard, various options have been proposed for performing fenestration (holes) in a newly implanted SG: by using a laser, as well as using the rigid side of the guidewire delivering SG. However, the method of performing fenestration using a special catheter with a puncture needle at its end is recognized as the safest. Performing such fenestration of the SG is associated with difficulties in visualizing occluded vessels and the impossibility of providing navigation for endovascular revascularization, which, in turn, can lead to iatrogenic damage to the arterial wall and massive bleeding. In addition, for the introduction of conductors and instruments for fenestration into the branches covered by the main trunk of the graft, additional accesses are required in the peripheral sections of several interested vessels.

Closest to the claimed technical essence is the SG "Fenestrated stent grafts" (patent US 10376395 B2), which is taken as a prototype.

This SG is an intravascular prosthesis made of PTFE or Dacron, reinforced with a metal wire frame in the form of Gianturco zigzag Z rings made of titanium nickelide, which are fixed together with non-absorbable surgical sutures. Known SG has a diameter of 20 to 40 mm and a length of 100 to 250 mm. The placement of the holes (fenestres) corresponds to the personalized model of a particular patient. The edges of the holes and the proximal and distal ends of the SG were treated with non-absorbable surgical suture and marked with radiopaque markers made of gold or other radiopositive material.

Despite the active use of such SG in clinical practice, this model is not without a number of shortcomings. SG described in the prototype is not universal and is applicable only in a certain anatomical region of the aorta. In addition, it is made only for a specific patient, taking into account its anatomical features.

The diameter of the SG rings should not exceed the size of the patient's unchanged aorta by more than 15%. An error in calculations and making it with a large diameter can lead to complications both in the intra- and postoperative periods. This is due both to the incomplete expansion of the walls of the SG and to the excessive and uneven pressure of the rings on the artery wall. In addition, the process of manufacturing such a personalized SG is laborious and can take up to 4 months. Such a long waiting period may increase the risk of developing severe, life-threatening complications of aneurysmal disease.

The coating of this SG is PTFE, and as you know, this is a practically impermeable material (it has a low porosity) for erythrocytes. Therefore, if the visceral vessels are blocked in violation of the implantation technique of such a SG, this leads to hypoperfusion and ischemia of vital organs. On the other hand, an increase in the porosity of the material can lead to the appearance of endoleaks (“On the choice of material for the creation of vascular implants (Literature review). SCIENTIFIC ELECTRONIC JOURNAL “INNOVA” No. 2 (3) 2016.”).

The process of positioning SGs with prefabricated holes is difficult and requires precision engineering. An error at this stage can lead to endoleaks, breakage, and deformities of peripheral SGs inserted into visceral arteries.

The above disadvantages of the SG, described in the prototype, do not allow for its use in wide clinical practice, since they are suitable only for solving a narrow range of problems.

The technical result of the present invention is to create a universal SG by using a self-expanding mesh with diamond-shaped cells with the possibility of changing their configuration in accordance with the diameter of the aorta and located inside its woven material made of polyethylene terephthalate (lavsan) attached to the mesh along its entire length and width by nodal sutures with non-absorbable suture.

This result is achieved by the fact that in the known stent-graft for the treatment of aneurysms and aortic dissection, consisting of an outer element and an inner element, which is made of woven material and is located inside the outer element, and the proximal and distal ends of the SG are marked with radiopaque markers, according to the invention, the outer element is made in the form of a self-expanding mesh with a diameter of 20-50 mm and a length of 150-200 mm, containing diamond-shaped cells with the possibility of changing their configuration in accordance with the diameter of the aorta. The woven material of the inner element, attached to the outer element with interrupted sutures from a non-absorbable surgical thread, is a lavsan (polyethylene terephthalate) fabric with a permeability for blood with heparin from 50 to 150 ml/cm ² /min at a pressure of 120 mm Hg. Art. with the possibility of controlled preservation of the endoleak inside the SG.

The execution of the outer element of the SG in the form of a self-expanding mesh increases the strength of the structure, which prevents breakage and deformation during implantation.

The manufacture of SG with diamond-shaped cells, with the possibility of changing their configuration in accordance with the diameter of the aorta, provides free passage of the instrument for antegrade perforation, which prevents the formation of endoleaks without creating an obstacle to blood flow inside the SG lumen. This shape of the cells ensures the mobility of the walls of the SG and the possibility of their tight fit in the zone of a healthy aortic wall, which enhances the frame properties of the structure, and also prevents the spread of aneurysmal deformation of the vessel with its subsequent dissection.

The diameter of the outer element in the form of a self-expanding mesh is 20-50 mm and its length is 150-200 mm due to the anatomical dimensions of the aorta in the areas of the proposed stenting. And changing these indicators depending on the size of the aorta allows you to adapt it to the maximum for any patient.

Production of an internal element of the SG from a woven material of lavsan (polyethylene terephthalate) fabric with a permeability for blood with heparin from 50 to 150 ml/cm ² /min at a pressure of 120 mm Hg. Art. with the possibility of controlled preservation of the endoleak inside the SG allows to achieve controlled porosity of the SG wall. Against the background of heparin, it provides blood supply to vital organs when the aortic branches are blocked by the construction, and makes it possible to create an x-ray "road map" against the background of the use of a radiopaque substance, i.e. a full-fledged image of the aorta and its branches with all the details that is necessary for accurate perforation and further prosthetics of the great vessels extending from the aorta, and when heparin is canceled, the porosity becomes zero, which separates the aneurysm cavity from the SG lumen and excludes endoleaks.

The location of the woven material made of polyethylene terephthalate (lavsan) inside the outer element and its fixation to the self-expanding mesh with interrupted sutures with non-absorbable surgical thread allows avoiding the windage of the coating and minimizing the possibility of endoleaks.

The installation of the proposed SG in arthroplasty of aneurysms and aortic dissection is carried out using a standard delivery system against the background of the use of heparin and a radiopaque substance. The SG is delivered to the installation site in the aorta, and then a guidewire with a guiding catheter is passed through its trunk to the mouth of the aortic branch.

Perforation of the internal element of the SG is performed with a conductor opposite the mouth of the aortic branch blocked by the SG, after which the guiding catheter is removed. This method of perforation eliminates the need for additional surgical approaches in the patient to the peripheral parts of the involved vessels.

The next step through the lumen of the established proposed SG for the treatment of aneurysms and aortic dissection, a peripheral SG is inserted into the aorta through its perforated wall along a guidewire. They can be any SG used in vascular surgery for arterial stenting (for example, SG FLUENCY). Fixation of peripheral SG in the artery is carried out by inflating the balloon. In this case, the proximal end of the peripheral SG is fixed in the corresponding cell of the external SG element and deforms it, while ensuring reliable fixation of the structure, after which the balloon and conductor are removed. It is important to note that this method of perforation and placement of peripheral SG can be used for each branch of the aorta blocked by SG. Moreover, heparinization and preservation of the endoleak continue until the end of the installation of the last peripheral SG.

This method of FH placement in arthroplasty of aneurysms and aortic dissection is technically simple and versatile, and also allows high-precision FG implantation, perforation in the required location, and placement of peripheral FG, while avoiding its breakage and deformation.

We have conducted studies of the proposed SG on a silicone phantom of the aorta, where aneurysmal expansion was modeled with and without dissection. In the study using a perfusion pump, a pulsating blood flow was simulated with a maximum pressure of 200 mm. rt. Art. The contour of the silicone phantom of the aorta was filled with a blood-substituting solution, simulating the rheological properties of native blood. SG was established using a standard delivery system against the background of the use of heparin and a radiopaque agent. Then, a conductor with a guiding catheter (the end of which is bent at a right angle) was passed through the SG, and opposite the mouth of the aortic branch, the internal element of the SG was perforated, the guide was inserted into the lumen of the artery, and the guiding catheter was removed. A peripheral SG was inserted through the conductor through the SG lumen on a balloon of the required diameter, and the balloon was inflated. At the same time, the proximal end of the peripheral SG was securely fixed in the SG cell, deforming it. The balloon and conductor were removed. The procedure was repeated for endoprosthesis replacement of all necessary branches of the silicone aortic phantom. Separately, the permeability of the SG wall was checked by connecting it to the circuit of the efferent therapy apparatus, as well as the flow of blood through the SG wall: on heparin 5 thousand IU (at the rate of 5 thousand IU per 85 kg of the intended patient's weight), while the permeability was from 50 to 150 ml/cm ² /min existed for 2 hours, then after the exclusion of the presence of heparin in the blood, the permeability of the internal element of the SG became zero.

Unlike the known SG, where the endoleak is undesirable, the proposed SG is made with the possibility of temporary preservation of the endoleak. This makes it possible to maintain the blood supply to vital organs for the entire procedure of SG implantation and the required amount of peripheral SGs until the blood supply is normalized, as well as to obtain an X-ray picture in a situation caused by SG implantation.

For a better understanding, here are illustrations of the SG:

Fig. 1 - SG for the treatment of aneurysms and aortic dissection, where:

1 - The outer element of the SG, made in the form of a self-expanding mesh;

2 - The inner element of the SG, made of polyethylene terephthalate (lavsan), located inside the outer element;

3 - Fastening the inner element of the SG to the outer interrupted sutures with non-absorbable surgical thread;

4 - X-ray contrast markers;

a - SG diameter 20-50 mm;

b - SG length 150-200 mm.

Fig. 2 - SG for the treatment of aneurysms and aortic dissection with peripheral SG, where:

1 - The outer element of the SG, made in the form of a self-expanding mesh;

2 - The inner element of the SG, made of polyethylene terephthalate (lavsan), located inside the outer element;

3 - Fastening the inner element of the SG to the outer interrupted sutures with non-absorbable surgical thread;

4 - X-ray contrast markers;

5 - Peripheral SG;

6 - Wall of the outgoing artery;

7 - Fixation of the proximal end of the peripheral SG in the SG cell with its deformation.

The advantages of this SG are that it is universal and does not require a long wait for manufacturing in the factory, which greatly facilitates the technique of implantation and perforation, while preventing the occurrence of such formidable complications for the patient as endoleaks, and due to controlled permeability, it prevents ischemia of vital organs , supplying blood from the overlapped SG branches of the aorta.

To date, the proposed SG for the treatment of aneurysms and aortic dissection has passed a series of tests on silicone aortic phantoms. The conducted studies have confirmed its high functionality and readiness for preclinical trials (testing on primates).

SG for the treatment of aneurysms and aortic dissection was developed by the authors and tested on a silicone phantom in the Department of Vascular and X-ray Endovascular Surgery of the Federal State Budgetary Institution “RNDRHT named after N.N. acad. A.M. Granov "M3 RF.

Claims (5)

1. Stent graft (SG) for the treatment of aneurysms and aortic dissection, consisting of an outer element and an inner element, which is made of woven material and is located inside the outer element, and the proximal and distal ends of the SG are marked with radiopaque markers, characterized in that the outer element made in the form of a self-expanding mesh with a diameter of 20-50 mm and a length of 150-200 mm, containing diamond-shaped cells with the possibility of changing their configuration in accordance with the diameter of the aorta, and the woven material of the inner element attached to the outer element with interrupted sutures from a non-absorbable surgical thread, is a lavsan (polyethylene terephthalate) cloth with a permeability for blood with heparin from 50 to 150 ml/cm ² /min at a pressure of 120 mm Hg. Art. with the possibility of controlled preservation of the endoleak inside the SG. 2. The method of installing the SG according to claim 1 during arthroplasty of aneurysms and aortic dissection, in which the SG is delivered to the installation site in the aorta, and the SG is made of a metal outer element and a woven inner element, the outer element is made in the form of a self-expanding mesh containing diamond-shaped cells with the possibility of changing their configuration in accordance with the diameter of the aorta, and the woven material of the inner element attached to the outer element with a non-absorbable surgical thread is a lavsan (polyethylene terephthalate) cloth with a permeability for blood with heparin from 50 to 150 ml/cm ² /min, then a conductor with a guiding catheter is passed through the lumen of the SG to the orifice of the aortic branch, the conductor perforates the internal element of the SG opposite the orifice of the aortic branch through the corresponding cell of the external element of the SG, the guiding catheter is removed, the guide catheter is inserted along the guide into the artery on the balloon through the perforated internal element of the SG peripheral SG, at the same time, its proximal end is left in the corresponding cell of the external SG element, by inflating the balloon, the peripheral SG is fixed in the artery, while its proximal end is deformed in the corresponding cell of the external SG element, the balloon and conductor are removed, and during the installation of the SG and the peripheral SG, heparinization is performed and save the endoleak during the installation of the SG and peripheral SG. 3. The method according to claim 2, in which, when arthroplasty of the remaining necessary branches of the aorta, the conductor perforates the internal element of the SG opposite the mouth of the corresponding aortic branch and removes the guiding catheter, after which the operation is repeated for each of the branches of the operation: - institution through the conductor into the artery on the balloon through the perforated internal element of the SG of the peripheral SG, - by inflating the balloon for fixing the peripheral SG in the artery, while its proximal end deforms the corresponding cell of the external SG element, and removing the balloon and guidewire, and the patient's heparinization and preservation of the endoleak continue until the last peripheral SG is installed.

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