Patent Application
20110245916
This application claims foreign priority under Paris Convention and 35 U.S.C. §119 to Korean Patent Application No. 10-2010-0031234, filed Apr. 6, 2010 with the Korean Intellectual Property Office.
This invention relates to a ventricular assist device (VAD), and more particularly to an improved polymer valve and a pulsatile conduit-type ventricular assist device using the polymer valve to substantially expand a device life span and durability.
Heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side. A human heart carries four valves: a bicuspid valve between a right atrium and a right ventricle; a pulmonary valve between a pulmonary artery and a right ventricle; an aortic valve between a aorta and a left ventricle; and a mitral valve between a left atrium and a left ventricle. In recent years, artificial heart valves have been developed to replace malfunctioning heart valves. Artificial heart valves include mechanical, biological and polymer valves.
One of the major drawbacks of mechanical heart valves is that patients with these implants require consistent anti-coagulation therapy. Clots formed by red blood cell and platelet damage can block up blood vessels and lead to very serious consequences. Clotting occurs in one of three basic pathways: tissue factor exposure, platelet activation, or contact activation by foreign materials, and in three steps: initiation, amplification, and propagation.
In order to overcome the limitation of such mechanical heart valves, biological valves are introduced in 1969. Biological valves are valves of animals, like pigs, which undergo several chemical procedures in order to make them suitable for implantation in the human heart. There are some risks associated with a biological valve such as the human body's tendency to reject foreign material, thus resulting in a replacement implantation in about ten to fifteen years.
A recent introduction is a polymer valve which is cost effective compared to mechanical or biological valve and enables fabrication of a desired shape with ease. A polymer valve varies to a bi-leaflet and tri-leaflet type.
U.S. Pat. No. 6,579,223 discloses an artificial valve having a stretchable bladder with a blood inlet and a blood outlet. for pumping blood to stretch and expand during the blood filling phase, and elastically contract to its normal size during the blood ejection phase.
U.S. Pat. No. 6,958,076 discloses an artificial hear valve comprising opposing pliable nonbiological leaflet members to shift between a first normally open position so blood may flow in a first direction through an axial passageway and a second closed position so blood fluid is prevented from backflowing through the axial passageway. The leaflets are normally open and only closing upon reversal of fluid flow to the second direction, and an elongated hollow support member receives the leaflet members.
Such conventional device has limitation since a metallic material is employed in the valve which may result in generation of unwanted thrombus in the blood system and limitation in dispersing backflow pressure, without which a valve needs to be replaced in a frequent manner. The valve replacement means an additional cost to a patient and lack of valve durability.
The invention is contrived to overcome the conventional disadvantages. Accordingly, an objective of the present invention is to provide a polymer valve to evenly distribute force and pressure applied to the leaflets to improve a valve life span and durability.
Another objective is to provide a polymer valve for a VAD with a cost-effective simplified structure to save more patients suffering from blood valve malfunctioning.
A further objection is to provide an improved polymer valve and a pulsatile conduit-type VAD that substantially prevents blood clotting (thrombosis) and dissolution or destruction of red blood cells from occurring in blood vessels of a heart patient who receives its assistance by employing non-metallic bio-friendly materials.
A still further objective of the prevent invention is to enable a heart patient to use the blood valve for a longer time period in form of either extracorporeal life support or surgical implantation.
To achieve these and other objectives, a prosthetic blood valve comprises a base body having a hollow therethrough; opposing props extending from the body to partition opposing inclined ridges of the body so the inclined ridges and each top of the props define the hollow and form an upper surface of the body; and a singular leaflet attached to and along the inclined ridges and the prop tops to cover the hollow, wherein the singular leaflet has a substantially central opening between the props so the leaflet is formed of a flexible material, whereby a forward or outward blood flow passes through the opening and a reverse flow or backflow of blood leads to opposing leaflet portions around the opening being abuttingly pulled to each other to thereby prevent the blood backflow.
In the prosthetic blood valve, the singular leaflet may be formed of a polymer film, preferably a polyurethane film. The opening is substantially shaped in a letter ‘U’ when viewed from a side of the inclined ridges. The U-shaped opening serves to evenly distribute a blood flow pressure and force toward the singular leaflet. The opening is substantially shaped in a top-down arch when viewed from a side of the inclined ridges. Here, the arch-shaped opening serves to evenly distribute a blood flow pressure and force toward the singular leaflet.
In an embodiment, a blood pump device comprise first and second prosthetic blood valves aligned to allow a blood flow from the first value to the second valve; an elastic conduit formed between the blood valves; and a housing to enclose the conduit, wherein said each blood valve comprises: a base body having a hollow therethrough; opposing props extending from the body to partition opposing inclined ridges of the body, wherein the inclined ridges and each top of the props define the hollow and form an upper surface of the body; and a singular leaflet attached to and along the inclined ridges and the prop tops to cover the hollow, wherein the singular leaflet has a substantially central opening between the props, wherein the leaflet is formed of a flexible material, whereby a forward or outward blood flow passes through the opening and a reverse flow or backflow of blood leads to opposing leaflet portions around the opening being abuttingly pulled to each other to thereby prevent the blood backflow; whereby an increased air pressure in the housing serves to deflate the conduit which leads to a blood outflow through the second valve opening with the first valve opening closed and a decreased air pressure in the housing serves to inflate the conduit which leads to a blood inflow from the first valve through the first valve opening with the second valve opening closed. The blood pump device may further comprise an air pump connected to the housing to control the air pressure in the housing.
Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended
These and other features, aspects and advantages of the present invention will become better understood with reference to the accompanying drawings, wherein:
Referring to the accompanying drawings, preferred embodiments of the present invention will now be explained.
For a better performance, the prosthetic blood valve 10 further comprises a singular leaflet 14 attached to and along the inclined ridges 13 and the prop tops 50 to cover the hollow 30. In this construction, the singular leaflet 14 has a substantially central opening 40 between the props 12. It is preferred that the leaflet 14 is formed of a flexible material. This construction results in a refined mechanism in which a forward or outward blood flow passes through the opening 40 and a reverse flow or backflow of blood leads to opposing leaflet portions 15 around the opening 40 being abuttingly pulled to each other to thereby prevent the blood backflow.
In an embodiment, the singular leaflet 14 is formed of a polymer film. The singular leaflet 14 may be formed of a polyurethane film. The opening 40 is substantially shaped in a letter ‘U’ when viewed from a side of the inclined ridges 13 so that the U-shaped opening 40 serves to evenly distribute a blood flow pressure and force toward the singular leaflet 14. Alternately, the opening 40 is substantially shaped in a top-down arch when viewed from a side of the inclined ridges 13 so that the arch-shaped opening serves to evenly distribute a blood flow pressure and force toward the singular leaflet.
FIGS. 5 and 6A-6B show another embodiment of the present invention to introduce a ventricular assist device or a blood pump device 20. As shown therein, the blood pump device 20 comprises first and second prosthetic blood valves 70 and 80 aligned to allow a blood flow from the first value 70 to the second valve 80. The blood pump device 20 further comprises an elastic conduit 21 formed between the blood valves 70 and 80, and a housing 22 to enclose the conduit 21.
In this construction, each blood valve 70 and 80 comprises, as shown back in
Under this construction, the ventricular assist device or a blood pump device 20 enables that an increased air pressure in the housing 22 serves to deflate the conduit 21 which leads to a blood outflow through the second valve opening with the first valve opening closed and a decreased air pressure in the housing 22 serves to inflate the conduit 21 which leads to a blood inflow from the first valve 70 through the first valve opening with the second valve opening closed.
The ventricular assist device or a blood pump device 20 may further comprise an air pump control 23 connected to the housing 22 to control the air pressure in the housing 22.
As discussed above, the prosthetic blood valve 10 and the blood pump device 20 serve to evenly distribute force and pressure applied to the leaflet to improve a valve life span and durability. The cost-effective simplified structure of the blood valve 10 would lead to saving more patients suffering from heart valve malfunctioning. Further, the blood valve using a polymer leaflet 14 in a singular format serves to prevent blood clotting or thrombosis and dissolution or destruction of red blood cells from occurring in blood vessels of a heart patient who receives its assistance by employing non-metallic bio-friendly materials, thereby enabling a heart patient to live a longer life with support in form of either extracorporeal life support or surgical implantation.
The mechanism of the prosthetic blood valve 10 and the blood pump device 20 will now be further explained with reference to the accompanying drawings. The opposing props 12 are preferably provided in pair. The ridges 13 are preferably formed in a downward slope on each side of the props 12. It is recommended that the prop pair 12 are formed symmetric to each other and consequently the ridges 13 are symmetric to each other perpendicular to the alignment of the props 12. The base body 11 and props 12 serve to support the singular leaflet 14 so be better formed of a bio-friendly material with an appropriate hardness. For example, a bio-friendly polycarbonate or polyurethane can be used for the body 11 and props 12.
The singular leaflet 14 is better formed of a flexible and pliable material. The leaflet 14 covers the hollow 30 of the body 11 and is sealed to and along the ridges 13 and prop tops 50. The leaflet 14 is better formed of a bio-friendly polymer material, preferably, a medical-purpose polyurethane. The leaflet 14 allows a blood inflow through the opening 40 along the arrow b in
The opening 40 is better formed of a letter ‘U’ when viewed from a side of the ridges 13 or from the arrow a in
Selectively, the opening may be formed in a V-shape 42 as shown in
Fabrication steps of the blood valve 10 are illustrated in
Referring to FIGS. 5 and 6A-6B, the ventricular assist device or blood pump device 20 will now be explained in further detail. The entrance 24 serves to communicate with a ventricle of a patient and the exit 25 communicates with an aorta of the patient. When the air inside the case 22 is suctioned out or deflated using the air pump control 23, the conduit 21 comes to inflate or expand since the lowered pressure in the case 22 triggers inflation of the conduit 21. Consequently, the inflation of the conduit 21 causes the blood to flow in through the first blood valve 70 with the second blood valve 80 serving to block backflow. That is, the inflation of the conduit 21 leads the opening of the first valve 70 to open while closing the opening of the second valve 80. Here, the pliable, elastic characteristic of the leaflet of the second valve is closed thereby preventing blood backflow.
As shown in
In an embodiment, the conduit 21 serves as an apical aortic conduit (AAC) so that when a ventricle pumps out blood, then the pumped out blood flows into the conduit 21 and the blood moves out through the second blood valve 80 to the exit 25 which communicates with an aorta. This will decrease load to the ventricle thereby curing a heart failure. A highly elastic material for the conduit 21 would maximize an effective decrease of load to the ventricle.
The air pump control 23 employed in the ventricular assist device 20 according to the present invention is formed to serve as AAC so that the malfunctioning of the air pump control 23 would not affect the heart functioning of the patient. Further, when the blood pump device 20 is provided such that it could be implanted, the patient can manually connect the air pump control 23 to the case 23 at home and detach the control 23 for the patient to go out for an outdoor activity, thereby maximizing product reliability,
Although the invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible by converting the aforementioned construction. Therefore, the scope of the invention shall not be limited by the specification specified above and the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-0031234 | Apr 2010 | KR | national |
