WO2018049492A1 - Method for producing an expandable heart valve stent from a polyurethane membrane and polyurethane membrane valve stent that can be implanted using a catheter in adult and pediatric patients - Google Patents

Abstract

Patent relating to an expandable polyurethane heart valve prosthesis. Constructed from a malleable stent containing the heart valve prosthesis, formed of three polyurethane strips adhered to fabric with three chromium-cobalt rods, which can be administered inside a catheter and implanted by percutaneous puncture. The polyurethane is applied in liquid state, forming a thin film which will form the three movable strips, without the use of stitches. The known properties of polyurethane for medical use will provide the prosthesis with durability, fatigue strength and resistance to calcification, which are indispensable features for use thereof in pediatric patients. The option of expanding the valve prosthesis, as the patient grows, enables said prothesis to be implanted in children, without the need for replacement until adulthood. The expansion procedure can be performed using a percutaneous approach, without the need for another operation, as long as the polyurethane prosthesis continues working, over the years. The development of said heart valve prosthesis can be considered a sustainable project, as long as it benefits patients, the environment and the popular economy.

Description

 "METHOD FOR OBTAINING AN EXPANSIBLE HEART VALVE STENT,

 FROM POLYURETHANE MEMBRANE AND STENT POLYURETHANE MEMBRANE VALVE TO

 CATHETER IMPLANTS IN ADULT AND PEDIATRIC PATIENTS ".

The main object of the present invention is to propose a method indicated to serve as a method of obtaining a cardiac valve stent model made from a synthetic membrane, type polyurethane to be employed in medical (surgical) procedures such as aim to solve problems of anatomical and functional problems related to cardiac malformations and acquired heart disease in humans in the following situations:

Stenosis with partial obstruction of the heart valves, compromising its opening or total obstruction, characterized by the absence of the heart valve and interfering with the passage of blood flow.

Insufficiency or congenital absence of some heart valves, with partial closure, compromising the closing of the heart valves. [004]

It is also an object of the present invention to protect the cardiac prosthesis: "STENT [EXPANSIBLE] HEART VALVE" contained within an expandable stent. The prosthesis is obtained from a structure polyurethane, which has desirable characteristics such as: biostability and biocompatibility with the recipient organism, as well as being efficient and resistant to fatigue, calcification, thrombosis and infection, in order to fulfill the biological function of the natural anatomical structure to be replaced. .

1. Polyurethanes 1.1 Origin and Market Use.

In 1848 French chemist Charles Adolphe Wurtz discovered that the Isocyanate groups reacted quantitatively with the primary hydroxy groups giving rise to urethane groups. For almost a century these reactions were limited to simple laboratory experiments. Until 1Θ37 the German Dr. Otto Bayer and colleagues took polyurethane on an industrial scale.

Currently polyurethane has been used in various areas of industry due to the possibility of obtaining this polymer with a great diversity of physical properties, being possible to obtain infinite variations of characteristics, by the combination of different raw material chemical properties, for example, the choice between the various types of aromatic isocyanates found in the market.

1- Polyurethane (PU) raw material and preparation

[007] We can define polyurethane as Material Group consisting of macromolecules with urethane bonding over and over, usually result of the reaction of isocyanate with hydroxyl groups, both di or polyfunctional. Here's the genetic reaction:

[008] Polyurethane Obtaining Genetic ReactionThe polyurethane chain configuration can range from regular or random to junction or cross, which will determine the physical properties of the synthesized material. Therefore one should be encouraged to the chain segments when it is desired to obtain products with specific properties, being factors directly linked to the type of raw material employed.

2- Siant Expandable

[009] The expandable stant system for heart valve prosthesis implantation.

MODEL

EXPANSIBLE HEART VALVE PROSTHESIS

POLYURETHANE

[010] The present invention will be described with reference to the figures below and classified as a "Expandable Polyurethane Heart Valve Prosthesis" model.

[011] The accompanying drawings show the different steps in the construction of the polyurethane prosthesis, based on the anatomical features of a CT study of the human aortic valve. [012] Figure 1: Stent design: Consisting of a pre-molded, laser-cut cobalt chrome mesh. Forman stent part: ring (1) 12.5 mm high and 3 flexible rods (2) 12.5 mm high, total height 25 mm.

[013] Diameter: In the "open" position, maintain the same uniform diameter with its base in the metal frame: 22 mm and in the "Closed" position: 5 mm.

[014] The program to be used for the design of this prosthesis will be generated through Software Sotid Work; This computer program generates a parametric and solid mesh.

[015] The stent receives polishing and a polytetrafluoroethylene bath to reduce the chance of thrombus formation. The stems have particle physical characteristics: they are flexible when subjected to fluid flow under pressure, reducing the wear of the membrane applied over the stent.

[016] Figure 2: Valve stent design: A thin 0.2 to 0.3 mm polyurethane membrane (1) was applied over the ostentate forming three flexible cusps without the use of sutures and a maximum opening mechanism equal to the diameter. larger stent 22 mm and hermetic closure at the base of the stems, mimicking the human aortic and pulmonary sigmoid valves. There is a limit of application of polyurethane (2), 6 mm from the lower edge of the stent, keeping this segment of the cobalt chrome mesh (3) free of polyurethane, exposing a surface suitable for stent attachment in the patient's valve annulus. [017] Figure 3: Drawing of the balloon catheter (1), integrated by a tube of two lumens: one distal and one lateral. The distal lumen path allows guidewire advancement to advance valve stent guidance. The lateral lumen will allow to inflate the balloon (2) with constant pressure, expanding the polyurethane valve stent (3), with increasing diameters of 12 to 22 mm.

The balloon 6 is positioned within the stent; then subjected to a reduction in diameter from 22 mm to 5 mm to be conditioned in the catheter. A sheath covers the entire length of the catheter to facilitate progression in the peripheral vessels to the heart.

[019] Figure 3 a: The balloon.allowing the expansion with uniform diameter of the stems (1) ø 2 to 3 mm larger expansion of the ring (2), for better fixation in the patient's valve ring, avoiding mobilization or embolization.

[020] The balloon has been designed to provide an exact diameter of 12 to 22 mm, maintaining a pressure set in accordance with the non-permeable balloon material. Stent valve expansion can be performed with balloons of increasing diameter, following the patient's growth, without the need for replacement of the prosthesis.

[021] The chosen balloon (12 to 22 mm) is positioned inside the valve stent, while the stent is reduced in diameter by a procedure called crimping, using a device called a crimping mechanism, which has a closing mechanism by means of a crimp. diaphragm, to symmetrically reduce the stent. STENT MECHANISM OPERATION OF POLYURETHANE VALVE

[022] Figure 4: The drawing shows the release mechanism of the polyurethane valve stent, conditioned in the catheter. After retracting the sheath (1), the valve stent (2) is ready, ready for balloon expansion (3). Radiopaque markings at the ends of the stent and balloon allow placement of the prosthesis in the heart valve ring under treatment.

(023] Figure 5: The drawing shows the stent implantation mechanism by balloon expansion (1), using a saline pressure injection, using a pressure syringe or insufflator, which generates pressures from various atmospheres. as the resistance to expansion expands, delivering varying volumes depending on the size of the balloon. Inflation begins immediately after the prosthesis delivery catheter 6 is actuated, expanding the stent rods (2) and opening the polyunethane valve (3). In order to visualize the position of the stent graft and the balloon in the valve ring by X-ray, platinum / iridium radiopaque markers were ligated according to stent length.

[024] Two additional markers on the proximal catheter shaft were placed to help position the dilating catheter in the patient's valve ring (4) relative to the guide catheter tip (5).

[025] Figure 6: The use of the Pear Balloon Catheter (1) allows the expansion of the lower stent bonnet (2), turning the mesh for better fixation in the valve ring (3). [026] The possibility of expanding the valve prosthesis, in the late postoperative evolution of the patient, allows this prosthesis to be implanted in children without replacement until the addicted age.

[027] The expansion procedure can be performed by percutaneous approach, avoiding classical thoracotomy in reoperations for valve replacement, provided that the polyurethane prosthesis remains functional over the years.

[028] Figure 7: Drawing showing the stenf valve at 4 different times for its clinical use: 12 mm (1), 15 mm (2), 18 mm (3) and 22 mm (4) in diameter.

[029] Figure 8: Drawing Showing the polyurethane valve stent at 4 different times for its clinical use: 12 mm (1), 15 mm (2), 18 mm (3) and 22 mm (4) in diameter.

[030] Indications: Patients with dysfunctional prosthesis may be submitted to polyurethane valve stent implantation and positioned inside the old prosthesis: Procedure called Implantevaive in vafve. The polyurethane valve stent can be implanted into any dysfunctioning heart valve: Mrtral, Tricuspid, Aortic, and Pulmonary, or positioned within tubular prostheses with or without a valve.

[031] This is a Sustainable Project: benefiting Patients: A reliable, durable, lower risk of dysfunction prosthesis will be offered for implantation in adults and children through a simpler procedure and lower surgical risk. Shortest ICU stay, and Hospital Information.

[032] Environment: No manipulation of animal tissue or chemical solutions will be necessary to preserve the prosthesis, which will be sterilized with Gamma Radiation.

[033] Economic Product: Manufacturing can be carried out on a large scale, therefore of low cost and high added value.

[034] Scientific Value: Several different models can be manufactured according to the needs of each patient.

[035] Social Satisfaction: It is a national product, evaluated by the scientific method (Experimental Surgery) and can obtain certification by ANVISA, to make it available to any citizen.

Claims

CLAIM "METHOD FOR OBTAINING AN EXPANDABLE HEART VALVE STENT FROM POLYURETHANE MEMBRANE AND POLYURETHANE MEMBRANE VALVE STENT, FOR IMPLANTATION BY CATHETER, IN ADULT AND PEDIATRIC PATIENTS". Consisting of a pre-molded cobalt chrome mesh, cut with a laser, polished and subjected to a polytetrafoamethylene bath. Form the stent (Figure 1) with a ring (1) 12.5 mm high and 3 flexible rods (2) 12.5 mm high, total height 25 mm. Construction of an expandable polyurethane heart valve stent without the use of suture lines to connect the three thin loops to the valve ring, with wide opening and closing without leaving a central leak. Formation of a thin polyurethane membrane (Figure 2) (1), measuring 0.2 to 0.3 mm, applied to the stent, forming three flexible cusps, imitating the human aortic and pulmonary sigmoid valves. There is a polyurethane application limit (2), 6 mm from the lower edge of the stent, keeping this segment of the cobalt chrome mesh (3) free of polyurethane, exposing a surface suitable for fixing the stent to the patient's valve ring. The balloon catheter (Figure 3, 3a) allows uniform expansion of the rods (1) and 2 to 3 mm greater expansion of the ring (2), for better flxation on the patient's valve ring, avoiding mobilization or embolization. The balloon was designed to provide an exact diameter of 12 to 22 mm, maintaining an established pressure according to the material of the semi-deformable balloon. Expansion of the valve stent can be performed with balloons of increasing diameter, following the patient's growth, without the need to replace the prosthesis. The stent release mechanism is a polyurethane valve, conditioned in the catheter. After withdrawing the vane (Figure 4) (1), the valve stent (2) is exposed, ready for balloon expansion (3). Radiopaque marks at the ends of the stent and balloon allow positioning the prosthesis in the ring of the heart valve being treated. The pear-shaped balloon catheter (Figure 5) (1) allows expansion of the lower edge of the stent (Figure 8) (2) , externally turning the mesh for better fixation in the vaivar ring (3), avoiding movement, rotation or embolization. The stents can be expanded with diameters of: (Figure 7) 12 mm (1), 15 mm (2), 18 mm (3) and 22 mm (4), as well as the polyurethane valve stent, for clinical use, with diameters: (Figure 8), 12 mm (1), 15 mm (2), 18 mm (3) and 22 mm (4). This is a Sustainable Project: benefiting Patients: A reliable prosthesis will be offered, lasting, with lower risk of dysfunction, for implantation in adults and children, through a simpler procedure, lower surgical risk. Shorter length of stay in the ICU and hospital stay. Environment: It will not be necessary to manipulate animal tissue or chemical solutions to preserve the prosthesis, which will be sterilized with Gamma Radiation. Economical Product: Manufacturing can be carried out on a large scale, therefore low cost and with great added value. Scientific Value: Several different models can be manufactured, depending on the needs of each patient. Social Satisfaction: this is a national product, evaluated using the scientific method (Experimental Surgery) and capable of obtaining certification from AN VI SA, to make it within the reach of any citizen.