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US-12623001-B2 - Aortic stent

US12623001B2US 12623001 B2US12623001 B2US 12623001B2US-12623001-B2

Abstract

The invention relates to a stent for placement at an aortic annulus that is expandable from an undeployed state to a deployed state comprising a stent frame having rows of cells with a proximal section and a distal section at a longitudinal axis of the stent, the stent frame being formed by a plurality of arms, the arms being connected to one another at connection points, and wherein the plurality of arms forms a plurality of diamond-shaped stent cells, in particular the rows of cells, formed of vertices at said connection points between the arms, a dry valve made out bovine pericardium arranged at least at the distal section of the stent with the dry bovine pericardium being configured to be rehydrated with a solution, a skirt surrounding the dry valve and comprising at least one of bovine pericardium and polyester, and one or more eyelets arranged at a distal end of some of the arms, with the eyelets being configured to fix the valve to the stent frame.

Inventors

  • Guilherme Agreli
  • KATHARINA KISS
  • Siegfried Einhellig

Assignees

  • CV CARDIOVASCULAR GMBH

Dates

Publication Date
20260512
Application Date
20220131
Priority Date
20210218

Claims (17)

  1. 1 . A stent for placement at an aortic annulus that is expandable from an undeployed state to a deployed state, the stent comprising: a stent frame having rows of cells with a proximal section and a distal section at a longitudinal axis of the stent, wherein a diameter of the distal section and the proximal section is larger than a diameter of a middle section arranged between the distal section and the proximal section, the stent frame being formed by a plurality of arms, the plurality of arms being connected to one another at connection points, and wherein the plurality of arms forms a plurality of diamond-shaped stent cells, in particular the rows of cells, formed of vertices at said connection points between the plurality of arms, and wherein the stent frame has a shape that corresponds to the shape of a nucleus of a torus, a dry valve made out of bovine pericardium arranged at least at the distal section of the stent with the dry bovine pericardium being configured to be rehydrated with a solution, wherein the dry bovine pericardium has a maximum tensile stress selected in a range of 20 to 25 MPa, wherein the rehydrated bovine pericardium has a tensile stress selected in a range of 12 to 15 MPa, and wherein the dry bovine pericardium is formed using a method of treatment comprising the steps of: (1) soaking the bovine pericardium treated with a crosslinking agent with a saline solution, (2) subsequent to step (1), contacting the bovine pericardium with an aqueous solution comprising Hydrogen Peroxide, (3) subsequent to step (2), contacting the bovine pericardium with an aqueous solution comprising PBS and EDTA, (4) subsequent to step (3), contacting the bovine pericardium with a solution comprising glycerol, ethanol and EDTA, and (5) subsequent to step (4), contacting the bovine pericardium with a glycerol solution, a skirt surrounding the dry valve and comprising at least one of bovine pericardium and polyester, two or more eyelets arranged at a distal end of at least one of the arms, wherein the dry valve is fixed to the at least one of the arms by connection to each of the two or more eyelets.
  2. 2 . The stent in accordance with claim 1 , wherein the dry valve comprises between two and six leaflets, with the leaflets being connected to the stent frame at said two or more eyelets.
  3. 3 . The stent according to claim 1 , wherein the stent comprises four rows of cells along the longitudinal axis.
  4. 4 . The stent in accordance with claim 1 , wherein the dry bovine pericardium has a calcium content selected in a range of 0.01 to 0.1 g/Kg.
  5. 5 . The stent according to claim 1 , wherein the skirt is arranged to cover at least the distal section of the stent frame from within.
  6. 6 . The stent according to claim 1 , wherein the skirt is arranged to cover at least the proximal section of the stent frame from within.
  7. 7 . The stent according to claim 1 , wherein the skirt is arranged to cover the whole stent from within.
  8. 8 . The stent according to claim 1 , wherein all ends of the plurality of arms at the distal and the proximal section lie in a common plane.
  9. 9 . The stent according to claim 8 , wherein the two or more eyelets of the distal end project beyond said common plane at the ends of the plurality of arms.
  10. 10 . The stent according to claim 9 , wherein the two or more eyelets lie in a further common plane.
  11. 11 . The stent according to claim 10 , wherein ends of the two or more eyelets remote from the ends of the plurality of arms lie in said further common plane.
  12. 12 . The stent according to claim 1 , wherein the stent further comprises one or more artery attachment eyelets for attaching the stent frame to an artery at at least one of the distal end and a proximal end of the stent frame.
  13. 13 . The stent according to claim 12 , wherein the one or more artery attachment eyelets for attaching the stent frame to an artery are configured to be attached to an aortic artery.
  14. 14 . The stent according to claim 1 , wherein the stent frame is made out of at least one of chromium, cobalt and Nitinol.
  15. 15 . The stent according to claim 1 , wherein a radius of curvature between the proximal section, the middle section and the distal section lies in a range of 5 to 50 mm.
  16. 16 . The stent according to claim 1 , wherein a radius of curvature between the proximal section, the middle section and the distal section lies in a range of 10 to 40 mm.
  17. 17 . The stent according to claim 1 , wherein a radius of curvature between the proximal section, the middle section and the distal section lies in a range of 20 to 30 mm.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of foreign priority under 35 U.S.C. § 119 of European patent application number 21157884.4, filed Feb. 18, 2021. The contents of this application are incorporated herein by reference in their entirety. INTRODUCTION The present invention relates to a stent for placement at an aortic annulus that is expandable from an undeployed state to a deployed state. A healthy heart facilitates oxygenated blood flow to the extremities. The heart is comprised of two chambers: the right chamber and the left chamber, which manage deoxygenated and oxygenated blood respectively. Deoxygenated blood from the upper and the lower extremities, travels through both caval veins, i.e. the vena cava superior and the vena cava inferior, into the right atrium. It is pumped through the tricuspid valve and into the right ventricle. During systole, when the ventricle is full, the tricuspid valve shuts and blood is pumped from the right ventricle through the pulmonary valve into the pulmonary artery and to the lungs where it is oxygenated. Following said oxygenation, blood is pumped back to the left side of the heart, i. e. the left atrium, through the pulmonary vein. As the atrium contracts, oxygenated blood flows from the left atrium through the mitral valve into the left ventricle. During systole, when the left ventricle is full, the left ventricle ejects the blood through the aortic valve into the aorta and to the rest of the body as well as to the coronary arteries which supply the heart muscle itself. A native aortic valve is one of the two semilunar valves of the heart and consists of three leaflets that are attached directly to the wall of the annulus. There are three cusps in the native aortic valve: the left coronary cusp (LCC), right coronary cusp (RCC), and the non-coronary cusp (NCC). The bellies of these cusps define the annulus of the native aortic valve. The annulus is predominantly circular or elliptical in shape. At the location of the cusp attachment, the aortic anatomy is typically at its largest diameter, and this defines the sinus region. The sinus of the aortic anatomy is critical to the healthy functioning of the heart as the coronary arteries, which carry oxygenated blood to the heart muscles, originate here. In patients with aortic stenosis, the integrity of the native leaflets and the annulus is compromised primarily due to calcification. A compromised valvular apparatus prevents the leaflets from fully opening during systole, thus affecting the hemodynamic functioning of the valve. In instances where this condition persists for an extended period of time, the left ventricle remodels to compensate, affecting cardiac performance and patient health. Surgical aortic valve replacement offers physicians the greatest flexibility regarding implant type—with choices of either a mechanical or bioprosthetic heart valve. The decision of whether an operation is possible is based on many factors, including age, surgeon preference, patient tolerance to blood thinners, and comorbidities. Surgical replacement is recommended for patients who are a low or intermediate surgical risk. Elderly patients who are at a high surgical risk or inoperable due to comorbidities require a different alternative. One drawback of existing technologies is leakage around the valve, termed paravalvular leakage (PVL). PVL is usually a result of at least one of the following malpositioning of an implant, calcium interference with implant expansion, incorrect sizing of the implant and/or implant migration. Therefore, biological tissues are widely used to make prosthetic replacements for heart valves and blood vessels as well as for transcatheter heart valves. They are connective tissues comprising collagen as the main component. Among these tissues, bovine pericardium is one of the most widely employed. Pericardial tissue is the sac surrounding the heart which provides a natural barrier to infection for the heart and prevents adhesion to the surrounding tissue. The pericardium also serves mechanical roles, for example, by preventing over dilation of the heart, maintaining the correct anatomical position of the heart, and regulating the pressure to volume ratio in the left ventricle during diastole. The structure of the tissue determines its behavior under loading in both conditions physiologic to the pericardium and as a prosthetic device. However, biological tissues obtained from the abattoir, in particular porcine and bovine cadavers, begin to degrade immediately. Therefore, the storage of such materials has proven to be difficult. For this purpose, a biological tissue, such as e.g. bovine or porcine pericardium or a heart valve, is usually chemically treated to improve its mechanical performance and immunogenic properties, reduce thrombogenicity and degradation, preserve sterility, and prolong the allowable storage period. Accordingly, biological tissues are known which can be