RU169013U1 - FLAT RIGID SUPPORT RING OF THE MITRAL VALVE - Google Patents

Abstract

The utility model “Flat rigid support ring of the mitral valve” refers to medicine, namely to cardiac surgery, and can be used for reconstructive operations on the mitral valve of the heart to eliminate its insufficiency. The support ring is made in the form of an oval with a ratio between the smaller and larger radii of the oval 4: 5, or 0.8. The oval is made with a truncated straight section, the length corresponding to the attachment zone of the base of the anterior mitral valve leaflet, the transition point of the oval arc to the straight section is a point with coordinates 0.94 of the length of the larger radius of the oval horizontally and 0.26 of the length of the larger radius of the oval, measured from the geometric center of the oval. The straight section of the oval is made open in the center. The ring can be made of titanium alloys in the form of a wire rounded in cross section with a diameter of 1.5-2.0 mm, and the outside can be sheathed with a rounded cuff made of synthetic fabric. The proposed support ring of the mitral valve is simple to manufacture, and also, when used in cardiac surgery, it differs significantly from previously known solutions in the simplicity of size selection, the simplicity of the implantation process, low trauma for the structures surrounding the mitral valve, and thanks to non-degenerated materials, a stably unchanged correction result is obtained, and also low thrombogenicity of the implant.

Description

The utility model “Flat rigid support ring of the mitral valve” refers to medicine, namely to cardiac surgery, and can be used for reconstructive operations on the mitral valve of the heart to eliminate its insufficiency.

The flat shape of the support ring is used in most operations, as it is most convenient for surgeons.

Known support ring prosthesis mitral and tricuspid heart valves (RU No. 24372, publ. 08/10/2002), consisting of an open frame and its lining, the frame is made of open rings of the trachea of cattle.

The disadvantage of this technical solution is the non-physiological round shape of the ring, as well as the fragility of the support frame from the rings of the trachea of cattle.

Known ring for annuloplasty (RU No. 83181, publ. 05.27.2009), made of bioinert materials, consisting of a frame in the form of a ring and sheathing. The frame around the perimeter contains a recess, and the skin around the entire perimeter contains a fold, and the fold of the skin is in the recess of the frame.

The disadvantage of this technical solution is the square profile of the support ring, as a result of which the stitching threads pass through the corner of the profile and, when tightened, will lead to its being pressed into the left ventricular myocardium with possible complications.

Known ring for annuloplasty (RU No. 121439, publ. 10.27.2012), containing an annular shell and a tie thread located inside it, one end of which is passed through tightly interconnected mechanisms for moving the thread and its fixation, mechanisms for moving the thread and its fixation installed inside the shell, the second end of the thread is fixed to the mechanism for moving the thread, the latter being made in the form of a device for incrementally displacing the thread, and the mechanism for fixing the thread is made in the form of a single-acting holding element.

The disadvantage of this technical solution is the non-physiological round shape of the ring, the complexity of the design of the locking lock, as well as the regulation of the size of the implanted ring.

The closest technical solution to the claimed is a two-part universal annuloplasty ring (RU No. 144684, publ. 08/27/2014), including a support retaining ring, repeating the shape of the fibrous ring of the mitral or tricuspid valve of the patient, the support ring consists of an elastic closed loop D- shaped with a width of 2-10 mm and a height of 2-5 mm and a rigid ring mounted in a groove made on the outer surface of the elastic contour to a depth of 0.25-1.25 mm. The shape of the rigid ring can be flat, saddle-shaped, having one or more elevations, the ring can be made in the form of a closed or open loop.

The disadvantage of this technical solution is that it does not allow you to pre-form the necessary geometry of the implantable support ring, depending on the anatomical and physiological characteristics of the patient.

The objective of the proposed technical solution is to expand the arsenal of devices for reconstructive operations on the mitral valve of the heart to eliminate its insufficiency.

The problem is solved using the proposed utility model, including a flat rigid support ring of the mitral valve with an open loop, and the ring is made in the form of an oval with a ratio between the smaller and larger radii of the oval 4: 5, or 0.8, in addition, the oval is made with a truncated in a straight section, along the length corresponding to the attachment zone of the base of the anterior mitral valve leaflet, the transition point of the oval arc into a straight section is a point with coordinates of 0.94 lengths of the larger radius of the oval horizontally and 0.26 of the length of the larger o the radius of the oval vertically, measured from the geometric center of the oval, as well as the straight section of the oval is made open in the center.

The front section of the arc is straightened to avoid obstruction of the excretory tract of the left ventricle. It is known that the main load in the mitral valve is the fibrous ring. With its flattening, developing during annulodilation, the tension on the fibrous ring increases. After implantation, the support ring takes over the load. It can be made of titanium or its alloys and their strength is sufficient to counter the load. Outside for hemming, the support ring can be covered with a round cuff in the profile made of synthetic fabric.

The flat rigid support ring of the mitral valve is made open in the center for the convenience of putting on a round cuff in the profile made of synthetic fabric.

According to the calculations below, the shape and proportions of the support ring are obtained, given relative to its larger diameter. Based on the indicated proportions, several sizes of a flat rigid mitral valve support ring are calculated.

The technical result of the utility model is the creation of a flat rigid support ring of the mitral valve with proportions that most closely match the physiological proportions of the mitral valve, the patient being operated on, which will significantly reduce the excessive load on the elements of the mitral valve, leaflets, tendon chords, papillary muscles.

The physiological proportions of the normal mitral valve were studied using anatomical preparations of the unchanged mitral valve of adults and by echocardiography of healthy volunteers (Bokeria, L.A. Mechanical stress in the cusps of the mitral valve and bioprosthesis in the mitral position. Effect of the geometry of the fibrous ring on the cusp tension. / L. A. Bokeria, II Skopin, MA Sazonenkov, EN Tumaev // Clinical physiology of blood circulation. - 2008. - No. 2. - pp. 73-80; Sazonenkov, MA Features of the anatomy normal mitral valve na / M.A. Sazonenkov // Bulletin of the Scientific Center for Cardiovascular Surgery named after AN Bakulev RAMS. Eighth annual session of the Scientific Center of Cardiovascular Surgery named after AN Bakulev RAMS with the All-Russian Conference of Young Scientists. - 2004. - V. 5 , No. 5. - p. 423; Sazonenkov, M.A., Geometric model of a normal mitral valve / M.A. Sazonenkov, E.N. Tumaev, I.I. Skopin // Bulletin of the Scientific Center of Agricultural Sciences named after A.N. Bakuleva RAMS Cardiovascular Diseases Fourteenth All-Russian Congress of Cardiovascular Surgeons. 2008. - T. 9, No. 6. - p. 55).

Were defined as significant for the physiology of the natural fibrous ring: the shape of the ring, the ratio of the larger and smaller radii, the length of the line of attachment of the front and rear cusps. To determine the shape of the support ring, the above parameters were selected precisely in the phase of the systole of the cardiac cycle (with echocardiography), which corresponds to the closed state of the valve.

The essence of the utility model is illustrated by drawings, which depict:

In FIG. 1 shows a model of a planar rigid support ring of the mitral valve in physiological proportions;

In FIG. 2 shows the shape and proportions of a normally formed mitral valve fibrous ring, where L is the attachment area of the anterior mitral valve leaf, and is the larger radius of the oval, b is the smaller radius of the oval;

In FIG. 3 shows the location of the straight section of the artificial flat rigid support ring, where the arc MN is the section of the oval arc corresponding to the line of attachment of the anterior mitral valve leaflet, and the line MN is the line along which the section of the oval should be cut;

In FIG. 4 is a diagram for calculating the coordinates of points (MN) on the line of a straight section of a flat rigid support ring, where MN is the line along which the section of the oval should be cut off, OA is the smaller radius of the oval; OV is the larger radius of the oval (a); N is the point at which the arc transitions to a straight section of the oval; OQ is the coordinate of the point N along the axis of the larger radius (defined by the length as 0.94 of the length of the large radius from the center of the oval); OR - the coordinate of the point N along the axis of the smaller radius (defined by the length as 0.26 of the length of the large radius from the center of the oval); α is the angle needed to calculate the coordinates of point N.

To calculate the physiological form of a flat rigid support ring, the following initial conditions must be observed:

1. The shape of the ring.

2. The relationship between the lengths of the straight (anteroposterior) and transverse (inter-commissural) axes.

3. Determine the fraction of the perimeter of the ring, which corresponds to the attachment line of the anterior mitral valve leaflet, which is inextensible during pathological processes, and its location on the arc.

4. Possible anatomically and physiologically justified deformations of the ring (making changes to its original form).

Based on the studies, numerical characteristics of the initial parameters were obtained:

1. The physiological form of the mitral fibrous ring is oval.

2. The oval has larger and smaller radii and the ratio between them.

According to ECHO-KG data of adult healthy volunteers, the anteroposterior diameter in systole was on average 25.78 ± 2.25 mm, and the intercommissural 34.85 ± 2.63 mm. The ratio of the anteroposterior diameter to the intercomisural in systole was 81.17%. To select a design sample, it is advisable to use rounded numbers. Therefore, to build a model of the support ring, a rounded relationship between the straight (smaller) and transverse (large) diameters of the ring is 80% (0.8, or 4: 5).

3. Studies of anatomical preparations of adults showed that the perimeter of the fibrous ring averaged 114.08 ± 12 mm. The base of the front cusp was 44.0 ± 6.65 mm long, which was 38.5%. To build a model of the support ring, a rounded relationship was chosen between the lobes of the perimeter of the fibrous ring occupied by the bases of the anterior (40%) and posterior (60%) cusps of the mitral valve (Fig. 2).

4. The portion of the mitral valve fibrous ring, located at the base of the anterior cusp, normal to systole and diastole, performs multidirectional movements. In diastole, it bends in the direction of the excretory tract of the left ventricle. The systole bends towards the center of the mitral foramen. Therefore, for the manufacture of a rigid support ring, it is advisable to make a straight section of the arc of the ring corresponding to the base of the front wing. This will allow a more pronounced displacement anterior to the anterior cusp to improve the overlapping of the mitral orifice, as well as to exclude arching of one or another degree of narrowing of the excretory tract of the left ventricle. That is, you need to determine which segment of the oval should be cut off, i.e. where to place a straight section of the arc in the artificial support ring of the mitral valve (Fig. 2).

The exact location of the points where it is necessary to make the transition of the arc of a flat rigid support ring to a straight section was determined using mathematical calculations:

Angle calculation

Angle MON = ϕ = 0.8 * 180 ° = 144 °.

The angle of AOW is ϕ / 2 = 72 °.

Angle α = 90 ° -72 ° = 18 °

The coordinates of the point N (x, y) are equal

x = PN = a cosα = a cos18 = 0.9511 a ,

y = NQ = bsinα = 0.8 a sin18 = 0.2472 a .

Distance NQ = y = 0.2472 a , distance PN = x = 0.9511 a , radius vector length

Arc calculation

All distances are expressed in fractions of size a = OB.

.Arc length

.

.Arc length

.

Arc length

The angle α, for which the segment ON divides the arc AB in the ratio of 0.8: 0.2, counting from point B, is 20.089 °.

Distance PN = 0.9392 a .

Distances NQ = PO = 0.2748 a .

.Distance

.

Since PN: OB = MN: DB, the length of the chord MN is 0.9785a.

The reliability of the calculation is confirmed by the good coincidence of the angle α with its estimated value (see above) and the fact that the radius ON lies between the length of the semi-major axis of the ellipse OB = a and the length of the minor axis of the ellipse ОА = b = 0.8а.

Schematically performed calculations are shown in FIG. 3.

The coordinates of the points where it is necessary to straighten the front section of the arc of a plane rigid support ring were calculated in several ways, and then the result was averaged. The resulting coordinates are expressed in fractions of the largest radius of the oval.

According to the results of the calculations, the coordinates of the flattening points of the arc almost coincided. The coordinates are expressed in fractions of the larger radius of the planar rigid support ring. According to the results of the angle calculation, the PN coordinates were 0.95a horizontally and the NQ coordinates were 0.25a vertically. According to the results of calculation along the arc, they amounted to 0.93a horizontally and 0.27a vertically. The averaged figures are 0.94a horizontally and 0.26a vertically, where a is the largest radius of the oval (Fig. 4).

The claimed flat rigid support ring 1 of the mitral valve, having a flat oval shape, consists of an arcuate section 2 and a straight, open in the center of section 3 (Fig. 1).

Utility Model Example

To determine the shape and size of the supporting rigid ring, the above physiological proportions of the normal mitral valve to the systole phase of the cardiac cycle were chosen during echocardiographic examination, which corresponds to the closed state of the valve. Based on these data and the obtained ratios of the flattening points of the arc, several sizes of flat rigid rings of the mitral valve were determined. A flat rigid support ring 1 is made for the fibrous ring of the mitral valve in the form of a rigid metal frame of titanium alloy. The shape of the support rigid ring 1 has a truncated oval in the form of an arcuate section 2 and a straight section 3 open in the center, which is technically convenient for putting on a synthetic sewing cuff.

For example, the larger diameter of the ring is 30 mm, respectively, the larger radius of the oval is 15 mm, then the smaller radius of the ring will be 15 × 0.8 = 12 mm. The coordinates of the flattening points of the arc are 15 × 0.94 = 14.1 mm horizontally and 15 × 0.26 = 3.9 mm vertically. The choice of the optimal size of the support ring for a particular patient is made after echocardiographic measurements of the reconstructed valve.

The material from which the flat rigid support ring is made is a titanium alloy, a wire rounded with a diameter of 1.5-2.0 mm, rounded in cross section.

The proposed flat rigid support ring of the mitral valve is simple to manufacture, and also, when used in cardiac surgery, it differs significantly from previously known solutions in the simplicity of size selection, the simplicity of the implantation process, the low-invasiveness for the structures surrounding the mitral valve, and thanks to non-degenerated materials, a stably unchanged correction result is obtained, and also low thrombogenicity.

Claims (3)

1. The support ring of the mitral valve, which is a flat rigid ring with an open loop, characterized in that it consists of two sections, the first of the sections represents the arc of the oval, while the oval has a ratio of smaller and major axis 4: 5, and the second of the sections connects the ends of the first section and made straight, not open in the center, separated from the major semi-axis of the oval by a distance of 0.26a and corresponds in length to the attachment zone of the base of the anterior mitral valve leaflet, while the mating points of the straight and ova nogo portions are spaced from the axis at a distance oval 0,94a, where a - the length of the major axis of the oval. 2. The support ring according to claim 1, characterized in that it is made of round wire with a diameter of 1.5-2.0 mm made of titanium alloys. 3. The support ring according to claim 1, characterized in that the outside is lined with a rounded cuff made of synthetic fabric.

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