RU2355360C2 - Biological atrioventicular heart valve and method for making thereof - Google Patents

Abstract

FIELD: medicine; cardiovascular surgery.

SUBSTANCE: valve contains a frame with a carrier ring corresponding with the natural shape of fibrous ring of human valve, a rack and an obturative shutter element attached to the frame. The carrier ring of the frame is segmented on perimetre, while the rack supports are V-shaped and interfaced to the ends of the specified segments of the carrier ring. The racks are provided with platforms to fix the tips of papillary muscles. The method consists that the carrier ring is segmented by number of racks. And the racks rest on the V-shaped bottoms to connect to the related segments of the carrier ring. The racks are supplied with platforms to fasten papillary muscles. The fibrous ring is fixed to the carrier ring of the frame all around, and the tips of papillary muscles are additionally reinforced with a biocompatible flap and fastened to rack platforms. The biocompatible material is used to make an attached cuff sutured to fibrous ring.

EFFECT: inventions allow for deformation of fibrous ring within heart cycle in conformity with deformations of fibrous ring of the recipient.

5 cl, 10 dwg, 1 tbl

Description

The invention relates to medicine, namely to cardiovascular surgery, and can be used in the surgical treatment of defects of the mitral and tricuspid valves.

Experience with the use of various heart valve prostheses shows that biological prostheses, compared with mechanical ones, when implanted in atrioventricular positions carry a lower risk of thromboembolism, which allows us to abandon permanent anticoagulant therapy in most patients. This is due to the physiological characteristics of the central blood flow through the bioprosthesis, as well as to the greater hemocompatibility of the biological leaflet as compared with the synthetic materials of the prosthesis locking element.

Known atrioventricular xenogenic bioprostheses made from the mitral valve of a pig without using a supporting frame. A description of such a heart valve and a method for implanting it are given in US Pat. No. 5,662,704 (MKI A61F 2/24, NCI 623/2, publ. September 2, 1997).

The disadvantages of this valve are due to the anatomical mismatch of the chordal apparatus - in the pig valve the chords are shorter. This leads to the need to lengthen the chordal apparatus using various technical solutions, for example, according to US patents No. 5662704, No. 5824067 and others, which complicates the design of the bioprosthesis and reduces the reliability of its operation.

Methods for the manufacture of known valves are described in the aforementioned US patents No. 5666704, No. 5824067 and consist in the fact that when they are executed from the mitral valve of a pig, the mitral valve complexes containing the fibrous ring, valves, chordal apparatus and the tops of the papillary muscles are selected, washed and preserved. . Then they cover the tops of the papillary muscles with a special material, fixing it around the chords with the formation of a sewing tube, which during surgery is fixed to the tops of the recipient's papillary muscles. The pork valve fibrous ring is also coated with a special material. The use of such material is a significant disadvantage of the known method.

Frameless bioprostheses are known in which this drawback is eliminated by cutting out the leaflet elements from biocompatible materials (for example, US patent No. 63582777, MKI A61F 2/24, NCI 623 / 2.12, published on March 19, 2002).

However, the common disadvantages of all types of frameless atrioventricular bioprostheses and methods for their manufacture are:

technical difficulties of implantation, forcing the surgeon to manipulate deep in the ventricle to fix the chordal apparatus of the bioprosthesis to the remnants of the recipient's papillary muscles;

the possibility of bioprosthesis dysfunction due to changes in the configuration and volumes of the left ventricle in the long-term postoperative period, when the length of the artificial chordal apparatus of the bioprosthesis can become insufficient or excessive, which will ultimately lead to flow regurgitation through the valve.

These disadvantages are partially devoid of the design of the atrioventricular valve and the method of its manufacture according to US patent No. 4665773 (class A61F 2/24, publ. April 7, 1987). The known valve contains a semi-rigid frame with a support ring of an ellipsoidal or kidney-shaped shape that mimics the natural shape of the fibrous ring of a human atrioventricular valve. The locking element of such a valve is made of a single sheet of biological or polymer material and consists of two valves, which provide a central character of the flow through the valve due to their simultaneous opening and closing. A design feature of this valve is the presence in the subvalvular space of supporting inclined struts with a spring effect, which are mounted on the support ring.

The disadvantages of the known design of the atrioventricular valve and method of its manufacture are:

the impossibility of natural contractions of the recipient's fibrous ring fixed on a continuous semi-rigid ring of the frame;

lack of a sewing cuff for intraoperative fixation of the valve to the fibrous ring, which technically complicates the implantation of the prosthesis;

protrusion into the ventricular cavity of structural parts consisting of foreign materials having gaps at the contact points, which increases the risk of thrombosis;

non-physiological configuration of the structure as a whole, not corresponding to the configuration of the natural atrioventricular valve due to the low profile in the presence of sufficiently massive and rigid supporting inclined racks in the ventricular cavity;

the impossibility of using allo- or xenogenic mitral valve cusps evolutionarily designed for long-term cyclic loading as a locking element.

The technical result of the invention is the creation of an atrioventricular valve of the heart on a flexible supporting frame while preserving the natural anatomical relationships of the cusp-chordal apparatus, which does not require fixation of this apparatus to the tips of the recipient's papillary muscles.

A biological atrioventricular valve of the heart is proposed, including a frame with a support ring corresponding to the natural form of the fibrous ring and having racks, and a locking element containing sashes attached to the frame.

The main difference of the proposed bioprosthesis is that the support ring of the frame is divided along the perimeter into separate sections, and the bases of the racks are made V-shaped and mate with the ends of these sections of the support ring, while the racks end with pads for fixing the tops of the papillary muscles.

The valve frame can be equipped with two uprights extending from the line of attachment of the posterior leaflet to the fibrous ring and located perpendicular to the intercommissural axis of the valve, with each upright having a platform for attaching papillary muscles.

Another difference is that the valve framework can be equipped with two uprights extending from the line of commissures and located parallel to the intercommissural axis of the valve, with each upright having a platform for attaching papillary muscles.

The difference is also that the valve frame can be equipped with two pairs of racks located perpendicularly or at a different angle to the inter-commissural axis of the valve, coming from the attachment line of the front and rear cusps to the fibrous ring, while in each pair of racks are directed towards each other and form a single platform for attaching papillary muscles.

A method of manufacturing the proposed bioprosthesis of a heart valve involves the selection of atrioventricular complexes from mammalian hearts, washing them in saline isotonic solutions, preparing and processing them while preserving the chordal apparatus and the tips of the papillary muscles and fixing them on the supporting frame.

The difference of the proposed method is that the support ring of the frame is divided into sections according to the number of racks, and the racks are made with V-shaped bases for connecting to the ends of the corresponding sections of the support ring and provide platforms for attaching papillary muscles, while the fibrous ring of the valve complex is fixed to the support the ring of the frame around the perimeter, and the tops of the papillary muscles are additionally strengthened with a flap of biocompatible material and attached to the platforms of the racks, moreover, from a biocompatible mat rial manufactured sewing cuff and fixed with sutures to its fibrous ring outside the ring of the support frame.

Due to the proposed structural design of the support ring and the connection of its sections with V-shaped bases of the uprights, it completely repeats the shape of the fibrous ring of a human valve and can be deformed during the cardiac cycle in accordance with the deformations of the recipient's fibrous ring.

The invention allows to completely eliminate such a very complex and inconvenient for the surgeon manipulation, as fixing in depth of the ventricle of the chordal apparatus of the bioprosthesis to the remnants of the recipient's papillary muscles, and also to avoid the problem of mismatch of the length of the chordal apparatus due to postoperative myocardial remodeling.

The invention is illustrated by drawings, in which Fig. 1 shows a general view of a biological atrioventricular valve, Fig. 2 shows a valve framework with two struts extending from the line of attachment of the posterior leaf to the fibrous ring and located perpendicular to the inter-commissural axis of the valve (side view), Fig. .3 - the same (top view), in Fig. 4 - the valve frame using two struts coming from the commissure lines and located parallel to the inter-commissural axis of the valve (side view), in Fig. 5 - the same (top view), 6 - valve frame using four racks located perpendicular to the inter-commissural axis of the valve (side view), Fig. 7 is the same (top view), Fig. 8 is a valve frame using four racks located at an angle to the inter-commissural axis of the valve (side view), Fig.9 is the same (top view), Fig.10 - fastening the sewing cuff to the fibrous ring of the valve.

The biological atrioventricular valve of the heart contains a flexible support frame with a support ring 1 and uprights 2 made of a material resistant to cyclic loads, for example polypropylene. The flexibility of the support ring is ensured by the fact that it is divided into sections by the uprights, and the uprights have V-shaped bases 3 with which they are connected to the ends of the respective sections. To produce the biological part of the atrioventricular valves (mitral and tricuspid), valve complexes are selected from the hearts of mammals, for example pigs, and they are washed using isotonic saline solutions, prepared and processed with the preservation of the chordal apparatus and the tips of the papillary muscles. When fixing the prepared valve complex on the supporting frame, the tops of the papillary muscles are additionally strengthened with a flap of biocompatible material (not shown) by wrapping and hemming, then fix to the platforms 4 racks 2 frames. The fibrous ring 5 of the valve complex is fixed to the supporting ring 1 of the skeleton along the entire perimeter, while the flaps 6 and the chordal apparatus 7 are located in the subvalvular space and are attached to the skeleton with the help of the fibrous ring and the tips of the papillary muscles. The final stage of manufacturing a bioprosthesis includes the formation of a biocompatible material of the sewn cuff 8 and fixing it with sutures 9 on the fibrous ring outside of the supporting ring 1 of the frame. The support ring completely repeats the shape of the atrioventricular fibrous ring of the valve and can be deformed during the cardiac cycle in accordance with the deformations of the fibrous ring due to V-shaped joints with uprights.

For the tests, four biological atrioventricular valves of the heart were made with fastening of papillary muscles on the frame:

using four racks located perpendicular to the inter-commissural axis I-I of the valve, when each pair of racks going from the line of attachment of the anterior and posterior cusps is directed towards each other, forming a single platform for attaching the papillary muscle;

using four racks located at an angle to the inter-commissural axis I-I;

using two racks, going from the line of attachment of the posterior leaflet to the fibrous ring and located perpendicular to the inter-commissural axis I-I of the valve, when each rack ends with a platform for fastening the papillary muscle;

using two racks extending from the line of commissures and located parallel to the intercommissural axis of the valve, when each rack ends with a platform for attaching papillary muscle.

The results of tests of all selected biological valves showed (see table) that all the anatomical relationships of the cusps, chordal apparatus, and papillary muscles were preserved in their designs, and the support ring has the necessary flexibility and can be deformed during the cardiac cycle in accordance with the deformations of the fibrous ring.

All valve elements are made of materials of biological origin, while the frame is also enclosed in a shell of biomaterial. Biological tissues can be both viable (allogeneic) and preserved, non-viable (xenogenic).

After preservation and sterilization, the valve can be subjected to additional modification by biologically active substances (antithrombotic, antibacterial, etc.).

Claims (5)

1. Biological atrioventricular valve of the heart, containing a frame with a support ring corresponding to the natural form of the fibrous ring of a human valve and comprising sashes attached to the frame, characterized in that the support ring is divided along the perimeter into separate sections, and the bases of the racks are V-shaped and paired with the ends of these sections of the support ring, while the racks are equipped with platforms for fixing the tops of the papillary muscles. 2. The heart valve according to claim 1, characterized in that the valve frame is provided with two uprights located perpendicular to the inter-commissural axis of the valve. 3. The heart valve according to claim 1, characterized in that the valve frame is provided with two uprights located parallel to the inter-commissural axis of the valve. 4. The heart valve according to claim 1, characterized in that the valve frame is provided with two pairs of racks located at an angle to the inter-commissural axis of the valve, while in each pair of racks are directed towards each other and form a single platform for fastening papillary muscles. 5. A method of manufacturing a biological atrioventricular valve of the heart, including processing the atrioventricular complexes with the preservation of the chordal apparatus and fixing on the support frame, characterized in that the support ring is divided into sections by the number of racks, and the racks are made with V-shaped bases and connected to the ends of the corresponding sections the support ring, while the fibrous ring is fixed to the support ring of the frame around the perimeter and from the biocompatible material is made sewing cuff and fixi they seam it to the fibrous ring outside of the support ring of the frame.

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