ARTIFICIAL HEART DESIGN

Abstract: An artificial heart design including a plurality of chambers defined by a flexible material (5) and at least one piezoelectric device (3). The piezoelectric device is activated to cause the flexible material to move between a constricted and unconstricted position. Accordingly, this results in a change in volume for the chamber causing blood to be forced from or into the chamber.

Description: ARTIFICIAL HEART DESIGN Related Applications This application claims priority to the extent available under 35 U.S.C. §119(e)(1) to provisional application no. 065,403, filed November 13, 1997. Background of the Invention The present invention pertains to an internal pumping apparatus. More particularly, the present invention pertains to an artificial heart design using a chamber that contracts and expands to facilitate a pumping action. Artificial heart designs are known in the art such as the Jarvis heart design first used in the 1980's. The Jarvis heart design included a rigid structure including a mechanical pump that would facilitate the pumping of blood through the artificial heart and through the patient using the artificial heart. The mechanical pump included a compressor that was supplied with air external to the patient. A drawback of such a design is the necessity that the patient be continuously connected to an external air supply so as to continue the operation of the pump. Accordingly, there is a need for an artificial heart design that overcomes the deficiencies of the mechanical pump devices described above Summary of the Invention The present invention provides an improved artificial heart design including a chamber that contracts and expands to facilitate a pumping action. In a first embodiment of the present invention, an artificial heart is provided having a spherical surface. Piezoelectric devices are mounted on the spherical surface in a honey comb arrangement. Each piezoelectric device has a control wire which supplies a voltage signal to it. A microprocessor or the like provides the timing so that when a piezoelectric device is activated, it bends slightly in a concave manner. Due to the spherical shape, the sum total on all the piezoelectric devices activated produces a depression in the surface of the sphere. This motion therefore decreases the volume of a chamber thus pushing the blood into the next chamber or into a vein or artery. When the piezoelectric device is deactivated or when an opposite voltage is applied, the chamber returns to the original state, thus forming a vacuum in the chamber and pulling blood into the chamber. Brief Description of the Drawings Fig. 1 is a schematic diagram of an artificial heart constructed according to an embodiment of the present invention. Detailed Description Referring to Fig. 1 , a schematic diagram of an artificial heart according to an embodiment of the present invention is shown. In this design, the basic heart design includes several items: a rigid frame 1, an outer layer or outer wall 2, a piezoelectric device layer 3, a support layer 4 (e.g., made of a Kevlar® material (DuPont Corporation); a blood resistant layer 5, a piezoelectric pump control system 6a-b; and a valve and timing control system 7a-b. The design of Fig. 1 is based on the operation of each chamber. In this embodiment, each chamber is composed of the above-listed items except for the valve and timing control system 7a-b. The rigid frame 1 includes a rigid wall or interior wall that provides the necessary support for the other components of the artificial heart. In this embodiment, the rigid wall is composed of a carbon composite so that it will be strong and light. For each chamber of a four-chamber heart, there are two walls shaped in a half-pie arrangement that slices into fourths the volume of the artificial heart. To provide fluid communication between chambers internal valves (e.g. valve 8) are provided the pass through rigid frame 1. The rigid frame 1 further provides the structure for the layers (described below) to push against. The outer wall 2 encloses the entire artificial heart. In this embodiment, the outer wall is made of a rigid material which may be plastic and is preferably bio-compatible in nature (due to its exposure to the internal organs of the body). The outer wall 2 provides protection to the internal piezoelectric devices and electronic control systems or the artificial heart. The piezoelectric device layer 3 and support layer 4 work together to form the basic pumping action for each chamber. In this embodiment, piezoelectric devices are placed on top of the support layer in a honey comb arrangement (in Fig. 1 , the outer layer is not shown in the left portion of the artificial heart). Control wires are attached to the piezoelectric devices to activate and deactivate each. In a preferred embodiment, the support layer 4 is made of strong, tear- resistant and flexible material such as Kevlar® material. The piezoelectric devices 3 and the support layer 4 combination are attached to rigid wall 2. The honeycomb design allows a sphere to indent over a small area. In this embodiment, the shape of each piezoelectric device is octagonal with a control wire attached. One skilled in the art will appreciate that other shapes for the piezoelectric devices can be chosen. The blood resistant layer 5 provides protection from the components of the heart that may not be bio-compatible. In this embodiment, the blood resistant layer 5 is a plastic that covers the interior of each chamber of the heart and would be in direct contact with the blood to be pumped. The blood resistant layer 5 also forms the interior of a chamber and is isolated from the other layers of the artificial heart. In this embodiment the pumping system of the artificial heart is designed to work to compensate for failures of other components. To this end, each chamber has two processors or the like for controlling the piezoelectric devices. The layout of the piezoelectric devices, in this example, is such that half are controlled by a primary processor 6a and half are controlled by a secondary processor 6b. Only half of the total set of piezoelectric devices are necessary to be activated in order to provide the appropriate pumping action. This allows a single processor failure to occur without a failure to the heart. It is also possible that a piezoelectric device may become defective over time and not work properly. Since this will result in a reduction in capacity, the secondary piezoelectric devices (i.e, those coupled to the secondary processor 6b) and the secondary processor 6b can take over in this event. In order to synchronize the pumping action of all chambers, a central control system 7a-b is provided. This control system 7a-b also may be a dual system where a second control system 7b is provided that can take over in the event of a primary system 7a failure. Another task of the central control system is the coordination of the electrical pulses from the nerve that regulates the heart with that of the chambers, allowing the heart to be regulated by the body. The primary control system 7a is also programmed so that the valves 10-11 into and out of the heart and those between chambers are activated properly. Accordingly, in operation, the primary control system 7a can be coupled to one or more nerves so that pulses from the nerves can be converted into control signals to the primary processor. The conversion of "signals" from such nerve(s) to a binary signal is considered to be known in the art. The primary processor then issues electrical signals to the individual piezoelectric devices causing those devices to bend. One skilled in the art will appreciate that the orientation of the piezoelectric devices should be selected so that when a certain voltage signal is applied to it, it will bend in (e.g., in a concave manner) so as to press into the volume defined by the flexible material of the chamber. Under the action of the piezoelectric devices, the flexible material that lines the chamber will then move from an unconstricted position to a constricted position where the volume in the constricted position is less than that for the unconstricted position. The result is that blood is forced from the chamber to another chamber or outside of the heart. Alternatively, the piezoelectric devices can be operated to move the flexible material from a constricted position to an unconstricted position resulting in an increase in volume for the chamber, thus drawing blood into the chamber from outside of the heart or from another chamber. The valve control system is programmed so as to time the opening and closing of valves so that blood can be moved through the artificial heart as desired. One skilled in the art will appreciated that the external valves 10-1 1 of the heart are made of material that will allow it to be sufficiently joined in fluid communication with the appropriate arteries and veins of the body. Stated another way, the chambers are operated in a two-stroke manner, based on a vacuum for receiving an intra-chamber transfer of blood and pumping for pushing the blood out of a chamber. During one cycle of pumping blood through a chamber an input chamber is relatively filled and emptied. In the filling operation the intra-chamber valve 8 is closed and the piezoelectric devices 3 are activated in a controlled manner to enlarge the volume of the chamber (thus creating a vacuum). The input valve 10 is opened to allow blood to enter the chamber (and is subsequently closed). During the emptying operation, the output valve 11 is opened, and blood in the chamber is pushed out by activating the appropriate piezoelectric devices 3 so as to reduce the volume of the chamber. The output valve is closed to form a vacuum in the chamber. The intra-chamber valve 8 is opened and the appropriate piezoelectric devices are deactivated to draw in the blood from the input chamber. The intra chamber valve is closed once the chamber is filled. The processors and valve control devices may be powered by a battery external to or internally to the body. One skilled in the art will appreciate that other forms of power supply may be used to facilitate the operation of the processors and valve control devices. The present invention can be used in other parts of the body to pump fluids such as air or blood. For example if the design of the device was a cylinder instead of a sphere, it could be possible to use this as an internal pumping apparatus for a major blood vessel. It could also be used to pump air instead of blood to assist people that have trouble breathing.

Claims: What is claimed is: 1. An artificial heart, comprising: at least a first chamber including an inner surface and an outer surface, each chamber including a flexible material at least partially lining the inner surface of said chamber, said flexible material adapted to move between a constricted and an unconstricted position; said flexible material at least partially encloses a first volume in said unconstricted position and at least partially encloses a second volume in said constricted position; and said first volume is greater than said second volume. 2. The artificial heart of claim 1 further comprising: a piezoelectric device coupled to said flexible material, said piezoelectric device adapted to cause said flexible material to move between said constricted and unconstricted positions. 3. The artificial heart of claim 2 further comprising: a control circuit coupled to said piezoelectric device, such that the control circuit is adapted to send a first signal to said piezoelectric device to cause said flexible material to move between said constricted and unconstricted positions. 4. The artificial heart of claim 3 further comprising: a second chamber disposed adjacent to said first chamber: and a first valve coupled between said first and second chambers, said first valve adapted to permit a flow of blood between said first and second chambers. 5. The artificial heart of claim 4 wherein said control circuit is further coupled to said first valve and is adapted to control an opening and closing of said first valve. 6. The artificial heart of claim 5 further comprising: a second valve coupled to said first chamber, said second valve adapted to permit a flow of blood between said first chamber and outside of said artificial heart. 7. The artificial heart of claim 6 wherein said control circuit is further coupled to said second valve and is adapted to control an opening and closing of said second valve. 8. An internal pumping apparatus comprising: at least a first chamber including an inner surface and an outer surface, each chamber including a flexible material at least partially lining the inner surface of said chamber, said flexible material adapted to move between a -9- SUBSTΓΓUTE SHEET (RULE 26) constricted and an unconstricted position; said flexible material at least partially encloses a first volume in said unconstricted position and at least partially encloses a second volume in said constricted position; and said first volume is greater than said second volume. 9. The internal pumping apparatus 8 further comprising: a piezoelectric device coupled to said flexible material, said piezoelectric device adapted to cause said flexible material to move between said constricted and unconstricted positions. 10. The internal pumping apparatus 9 further comprising: a control circuit coupled to said piezoelectric device, such that the control circuit is adapted to send a first signal to said piezoelectric device to cause said flexible material to move between said constricted and unconstricted positions. 1 1. The internal pumping apparatus 10 further comprising: a second chamber disposed adjacent to said first chamber; and a first valve coupled between said first and second chambers, said first valve adapted to permit a flow of fluid between said first and second chambers. 12. The internal pumping apparatus of claim 1 1 wherein said control circuit is further coupled to said first valve and is adapted to control an opening and closing of said first valve. 13. The internal pumping apparatus of claim 10 further comprising: a second valve coupled to said first chamber, said second valve adapted to permit a flow of fluid between said first chamber and outside of said internal pumping apparatus. 14. The internal pumping apparatus of claim 13 wherein said control circuit is further coupled to said second valve and is adapted to control an opening and closing of said second valve.

Inventors: BOWDEN RONALD E, BOWDEN, RONALD, E.
Applicants: BOWDEN RONALD E, BOWDEN, RONALD, E.
Application year: 1998
Main classification: A61F2
IPC codes: A61M1