Abstract:
The human heart is assisted in moving blood through blood vessels by alternately applying and relieving pressure about a blood vessel with a vessel constrictor. The blood flow is restricted to one direction along the blood vessel by restrictors. The application of pressure to the blood vessel may be timed with the heart beat.

Description:
TECHNICAL FIELD  
       [0001]     The present disclosure is generally related to blood pumping systems and, more particularly, is related to a system and method for pumping blood through the body of a patient.  
       BACKGROUND OF THE INVENTION  
       [0002]     There exists a shortage in donor hearts for heart transplant operations. The shortage of donor hearts is so severe that some patients, who are on heart transplant waiting list, die from heart failure before a donor heart can be found. Some of the problems associated with human-to-human heart transplant include the shortage of donor hearts; the need to match tissue type so that the donor heart is accepted by the body of the heart transplant patient; inability to anticipate when a donor heart will become available and schedule procedures in advance; and the need for geographical proximity. Once a donor heart has been harvested, the donor heart is refrigerated until it is transplanted in the body of a patient. However, even though the donor heart is refrigerated, it will degrade over time. Consequently, a patient needs to be geographically proximal to where the donor heart is transplanted so as to reduce the time that the donor heart is refrigerated.  
         [0003]     Due in part to the problems associated with human-to-human heart transplants, attempts have been made to provide heart transplant patients with “artificial” hearts and animal hearts. Such attempts have generally been experimental and have produced unsatisfactory results. In non-human-to-human heart transplant experiments, a patient has their natural heart removed and replaced by a non-human (artificial or animal) heart. The patient is then dependent upon the transplanted non-human heart until a human donor heart becomes available.  
         [0004]     An advantage of a artificial (man-made) heart is that the heart can be stored at a hospital waiting for a patient, thereby negating the need for geographical proximity, and procedures can be scheduled well in advance. Furthermore, an artificial heart can be made from materials that will not be rejected by the patient&#39;s body. However to date, artificial hearts have not proved effective. One reason, among others, that artificial hearts have been ineffective is that they can cause blood clotting, which can lead to strokes and other medical complications. To reduce the risk of blood clotting, patients generally receive drugs that thin their blood. However, blood-thinning drugs also have medical risks associated with them.  
         [0005]     Animal-to-human heart transplants have some of the general advantages of artificial hearts such as animal hearts can be easily procured and animal-to-human transplants can be scheduled in advance. However, animal-to-human heart transplants have so far proved unsuccessful for at least the reason that the human body normally rejects the foreign animal tissue.  
         [0006]     Thus, a heretofore-unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies. Among other needs, there exists the need for an apparatus that can assist a patient&#39;s heart in pumping blood so that the patient can survive until a human donor heart becomes available. There also exists the need for an apparatus that can pump blood through the patients body even when the patient&#39;s heart has failed or been removed.  
       SUMMARY OF THE INVENTION  
       [0007]     Briefly described, the present invention comprises a method of assisting the heart of a human body to move blood through the blood vessels of the body by alternately applying pressure to and relieving pressure from the exterior of a blood vessel of the body. The flow of blood through the vessel is restricted to one direction.  
         [0008]     One embodiment of the method includes coordinating the application of pressure to the blood vessel with the heart beat of the body.  
         [0009]     A system for pumping blood through the body includes a blood restrictor that allows blood flow though the blood vessel in a first direction and inhibits blood flow in the opposite direction and a blood vessel constrictor that constricts about the blood vessel to cause blood within the blood vessel to flow through the blood vessel and its blood restrictor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0011]      FIG. 1  is a diagram of a patient and blood pumping system.  
         [0012]      FIG. 2  is a diagram of the circulatory system of the patient of  FIG. 1 .  
         [0013]      FIG. 3  is a top view of a blood vessel constrictor.  
         [0014]      FIG. 4  is a cross sectional side view of the blood vessel constrictor of  FIG. 3 .  
         [0015]      FIGS. 5A-5C  are partial views of the blood vessel constrictor in operable states wrapped around the leg of the patient.  
         [0016]      FIG. 6  is a diagram of another embodiment of a blood pumping system.  
         [0017]      FIG. 7  is a diagram of an internal blood pumping system. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIG. 1  illustrates an embodiment of a blood pump system  10  for pumping and/or enhancing the pumping of blood through patient  12 . In some embodiments, the blood pumping system  10  replaces the patient&#39;s heart such that the blood pumping system  10  is solely responsible for pumping blood through the patient&#39;s body. In other embodiments, the blood pumping system  10  works in conjunction with the patient&#39;s heart to assist the heart in pumping blood through the patient&#39;s body. In this description, embodiments are described in which the blood pumping system  10  assists a heart in its pumping. However, those are non-limiting embodiments and are provided for the sake of clarity.  
         [0019]     For the purposes of illustration, the patient  12  is depicted as a human having a torso  14 , limbs  16 , which include arms  16 (A) and  16 (B) and legs  16 (C) and  16 (D), and a blood circulatory system comprising a heart  18 , arteries  20 , capillaries  22 , and veins  24 . (See  FIG. 2 .) The natural blood flow direction of the circulatory system is from the heart  18  through the arteries  20  to the capillaries  22  and through the capillaries  22  to the veins  24  and back to the heart  26 . The human body and its circulatory system are well known and are not discussed in detail.  
         [0020]     In one embodiment, a blood pumping system  10  includes an arterial blood restrictor  26  and a venial blood restrictor  28 , which are implanted in an artery  20  and a vein  24 , respectively. In this embodiment, the blood restrictors  26  and  28  are one-way check valves that inhibit blood flow counter to the natural blood flow of the body. In other words, the arterial blood restrictor  26  inhibits the back flow of blood towards the heart; and, the venial blood restrictor  28  inhibits the back flow of blood away from the heart. In this embodiment, the arterial blood flow restrictor  26  and the venial blood flow restrictor  28  are disposed in the body proximal to the torso  14  such that a significant amount of blood within the leg  16 (C) is bounded by the blood restrictors  26  and  28 . Exemplary blood restrictors include both mechanical valves such as, but not limited to, one-way check valves and biological valves such as, but not limited to, pig valves. Typically, blood restrictors are similar to heart replacement valves, which are well known in the art.  
         [0021]     The blood pumping system  10  also includes a controller  30 , an actuator  32  and a blood vessel constrictor  34 . As will be explained in detail hereinbelow, the blood vessel constrictor  34  circumscribes and extends externally along a therapy portion  36  of the leg  16 (C). The blood vessel constrictor  34  is coupled to the actuator  32  by a pressure line  36  which carries a fluid such as air, gas, liquid such as, but not limited to, saline liquid and silicone liquid from the actuator  32  to the blood vessel constrictor  34 . Responsive to activation by the actuator  32 , the blood vessel constrictor  34  inflates and deflates such that pressure and/or suction are applied to the therapy portion  36  of the leg  16 (C). In some embodiments, the blood vessel constrictor  34  is cuff like and is similar to a cuff of the type used to measure blood pressure or the like.  
         [0022]     In one embodiment, the patient  12  is coupled to a heart monitor  60  and a blood pressure monitor  62 , which are coupled to the controller  30  by an electrical connector  64 . The controller  30  monitors the patient&#39;s blood pressure and heart rate and causes the actuator  32  to inflate and deflate the blood vessel constrictor  34 . In some preferred embodiments, the controller  30  maintains the patient&#39;s blood pressure within a desired range using the blood vessel constrictor  34 . In addition, in some embodiments, the controller  30  causes the blood vessel constrictor  34  to inflate and deflate in rhythm with the patient&#39;s heart rate. The actuation of the blood vessel constrictor  34  can be offset from the pumping of the heart such that the blood vessel constrictor  34  is generally in rhythm with the systolic blood flow through the leg  16 .  
         [0023]      FIG. 3  illustrates the blood vessel constrictor  34  when the blood vessel constrictor  34  is not disposed around the leg  16 (C). The blood vessel constrictor  34  has opposed ends  40  and  42 , which define a longitudinal length  44 , and opposed ends,  46  and  48 , which define a transverse width  50 . The blood vessel constrictor  34  is made from a pliable material such as, but not limited to, nylon so that the blood vessel constrictor  34  can be wrapped around the leg  16 (C) by aligning the longitudinal length  44  with the length of the leg  16  and wrapping the blood vessel constrictor  34  around the leg such that the ends  46  and  48  are aligned. The ends  46  and  48  are adapted to couple together by fasteners such as snaps, Velcro, etc.  
         [0024]      FIG. 4  illustrates the blood vessel constrictor  34  as seen along line A-A of  FIG. 3 . The blood vessel constrictor  34  includes an inner wall  52  and an outer wall  54 , which together define a chamber  56 . In operable position, the blood vessel constrictor  34  is wrapped around the leg such that the inner wall  52  is adjacent to the leg.  
         [0025]     The pressure line  38  extends from the outer wall  54  to the actuator  32  ( FIG. 1 ). Responsive to fluid  58  being pumped into the chamber  56 , the chamber  56  expands. In some embodiments, the outer wall  54  has an elasticity coefficient different from the inner wall  52  such that the outer wall  54  is stiffer so that expansion occurs primarily at the inner wall  52 .  
         [0026]      FIGS. 5A-5C  illustrates cross-sectional views of the blood vessel constrictor  34  in operable position wrapped around leg  16 (C). In  FIG. 5A , the blood vessel constrictor  34  is in its relaxed state i.e.; pressure within the chamber  56  is approximately equal to atmospheric pressure. Consequently, leg  16 (C) is also at atmospheric pressure, and blood pressure within the leg corresponds to the natural blood pressure of the patient  12 .  
         [0027]     In  FIG. 5B , the blood vessel constrictor  34  is pressurized, i.e., the pressure is greater than the atmospheric pressure. Pressurization of the blood vessel constrictor  34  causes the inner wall  52  to constrict against the leg  16 , which in turn causes blood flow out of the leg through the venial restrictor  28 . The arterial restrictor  26  inhibits arterial reverse blood flow, i.e., and blood flow towards the heart  18  through the artery  20 .  
         [0028]     In  FIG. 5C , the blood vessel constrictor  34  is in suction mode; the pressure within the chamber  52  is less than atmospheric pressure. Consequently, the pressure experienced by the therapeutic portion  36  of the leg  16  is less than the atmospheric pressure and, the leg expands accordingly. The expansion of the therapeutic portion  36  of the leg  16  causes blood to flow into the therapeutic portion  36  via artery  20 . The venial blood restrictor  28  inhibits reverse venial blood flow, i.e., and blood flow through the vein  24  away from the heart  18 .  
         [0029]      FIG. 6  illustrates another embodiment of a blood pumping system. The leg  16  (D) of the patient  12  extends into a pressure/vacuum chamber  66 . The pressure/vacuum chamber  66  is generally cylindrical in shape having an open end  68 , which defines an opening  70  for receiving the leg  16 , and a closed end  69 .  
         [0030]     A curtain  72  is attached to the open end  68 . The curtain  72  is adapted to fit around the torso  14  of the patient  12  such that a generally airtight seal is formed around the torso  14  of the patient. The pressure/vacuum chamber  66  is coupled to the actuator  32 , via the pressure line  38  as described in  FIG. 1 . The controller  30  controls the pressure in the pressure/vacuum chamber  66 , and the pressure is raised to compress/pump blood from the legs  16  into the torso  14  and lowered to draw blood from the torso  14  into the leg  16 .  
         [0031]      FIG. 7  illustrates components of an internal blood pumping system  73  in cross-sectional view. A first blood flow restrictor  74 , a blood vessel constrictor  76  and a second blood flow restrictor  78  are serially disposed in the leg  16 (D) of the patient  12  around a blood vessel  80 , which can be a vein or an artery. Arrow  82  represents the natural blood flow direction within the blood vessel  80 . Thus, blood vessel  80  is illustrated as an artery, but this is merely for the sake of illustration. The first blood flow restrictor  74 , the blood vessel constrictor  76  and the second blood flow restrictor  78  are each connected to a pressure line  84 ,  86  and  88 , respectively, and the pressure lines  84 ,  86  and  88  are connected to the actuator  32  ( FIG. 1 ).  
         [0032]     The first and second blood flow restrictors  74  and  78 , respectively, and the blood vessel constrictor  76 , each have an inner wall  90 ,  92 , and  94 , respectively, and an outer wall  96 ,  98  and  100 , respectively, which define chambers  102 ,  104  and  106 , respectively. The inner walls  92 ,  94  and  96  abut the blood vessel  80  and are made from a pliable/elastic material. Each one of the inner walls  92 ,  94  and  96  expands inward towards the blood vessel  80  in response to pressure in its chamber  102 ,  104  and  106 , respectively. In some embodiments, the inner walls expand outward away from the blood vessel  80 , in response to a partial vacuum, i.e., suction, in its chamber  102 ,  104  and  106 , respectively.  
         [0033]     Generally, the first and second blood flow restrictors  74  and  78  are smaller than the blood vessel constrictor  76  and function as valves to permit blood flow into and out of the region of the blood vessel  80  that is circumscribed by the blood vessel constrictor  76 . The blood vessel constrictor  76  extends along and circumscribes a portion of the blood vessel  80 . The blood vessel constrictor  76  is adapted to constrict the circumscribed portion of the blood vessel  80  so as to squeeze blood therefrom. In some embodiments, the portion of the blood vessel  80  that is circumscribed by the blood vessel constrictor  76  is enlarged from its natural state to increase the volume of blood within the circumscribed portion. Typically, the enlarged portion of the blood vessel  80  has a diameter that is larger than the natural diameter of the blood vessel. The increased diameter of the enlarged portion can be the result of grafting additional veins/arteries onto the blood vessel or causing the blood vessel grow such that its diameter increases.  
         [0034]     In operation, the controller  30  signals the actuator  32  to cause the internal blood pump system  73  to pump blood through the blood vessel  80  in the natural blood flow direction  82  by sequentially and cyclically compressing and relaxing the first blood flow restrictor  74 , the blood vessel constrictor  76 , and the second blood flow restrictor  78 . An exemplary cyclic sequence is shown in Table 1.  
                                 TABLE 1                           Exemplary cycle of the internal blood pumping system.                First Blood       Second Blood       Stroke   Restrictor   Pump   Restrictor               A   Constricted   Constricted   Open       B   Open   Constricted   Constricted       C   Open   Open   Constricted       D   Constricted   Open   Open                  
 
         [0035]     In stroke A, the first blood restrictor  74  and the blood vessel constrictor  76  are constricted, i.e., pressurized such that they are applying pressure to the blood vessel  80 . The second blood restrictor  78  is open, i.e., no inward pressure or minimal inward is being applied to the blood vessel  80 . In some embodiments, components of the internal blood pumping system can be configured to apply a partial vacuum or suction to the blood vessel  80  when the components are in the “open” state, thereby causing the blood vessel  80  to expand. Stroke A corresponds to the state of the internal blood pumping system after blood has been pumped therefrom.  
         [0036]     In stroke B, the first blood restrictor  74  opens, the second blood restrictor  78  constricts, while the blood vessel constrictor  76  remains constricted. The constriction of blood vessel constrictor  76  prevents or inhibits reverse blood flow.  
         [0037]     In stroke C, while the first blood restrictor  74  remains open and the second blood restrictor  78  remains constricted, the blood vessel constrictor  76  opens, thereby allowing blood to flow into the blood vessel that is circumscribed by the blood vessel constrictor  76 . The constricted second blood restrictor  78  prevents reverse blood flow.  
         [0038]     In stroke D, while the blood vessel constrictor  76  remains open, the first blood restrictor  74  constricts and the second blood restrictor  78  opens. The constriction of the first blood restrictor  74  prevents or inhibits reverse blood flow when the blood vessel constrictor is constricted, and likewise, the opening of the second blood restrictor  78  enables/facilitates blood flow out of the internal blood pumping system  73  when the blood vessel constrictor  76  constricts.  
         [0039]     It should be remembered that table 1 is merely illustrative of one possible cycle and that other cycles having more or fewer strokes are also possible. Thus, table 1 is a non-limiting example and other cycles are included within the scope of the invention.  
         [0040]     It should be emphasized that the above-described embodiments of the present disclosure, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) of the disclosure without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present disclosure and protected by the following claims.