Abstract:
A circulation assist method and device is provided wherein the contraction and expansion of a balloon of an IABP system which has already been widespread as a device for pressure support are utilized as power source for operating a pump so as to realize the assist of stream volume. A cylindrical pump chamber is connected at one and the other ends thereof respectively with an inflow hole and an outflow hole. An inflow valve is provided at the side of the inflow hole for permitting blood to stream from the inflow hole into the pump chamber but preventing the backward stream, and an outflow valve is further provided at the side of the outflow hole for permitting blood to stream from the pump chamber into the outflow hole but preventing the backward stream. A balloon portion of a balloon catheter connected to the IABP system is fluid-tightly incorporated into the pump chamber and is pulsated, so that blood is sucked into the pump chamber through the inflow valve when the balloon is contracted, and is ejected therefrom through the outflow valve when the balloon is expanded.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention:  
           [0002]    The present invention relates to a circulation assist method and device and a blood stream control valve for mechanically replacing or assisting the pumping function of a heart for a short period of time for the purpose of treatment for serious heart failure.  
           [0003]    2. Discussion of the Prior Art:  
           [0004]    As assisted circulation, there are known mechanical assist means such as IABP, LVAD, V-A Pumping (PCPS by means of an artificial cardiopulmonary or a centrifugal pump) and the like. Of these, the IABP has been widespread these days. It is to be noted that the abbreviations used above means the following definitions herein:  
           [0005]    IABP: Intra-Aortic Balloon Pumping  
           [0006]    LVAD: Left Ventricular Assist Device  
           [0007]    V-A: Veno-Arterial  
           [0008]    PCPS: Perctaneous Cardiopulmonary Support  
           [0009]    In the IABP, a cannula is inserted from the thigh artery to set a balloon in the thoracic descending aorta. Gas is ejected into and sucked from the balloon, whereby the same is alternately expanded and contracted thereby to reverse the phase of blood pressure. Namely, the IABP is an assist means which aims at performing systolic unloading and disastolic augmentation and has been generally used for the reason that it can be easily manipulated even by physicians. On the other hand, the LVAD is an assist means for bypassing the left ventricle directly from the suction cannula of the left atrium by way of an artificial heart pump. This has been experienced only at a few facilities even in our country because the drive unit and the artificial heart pump are expensive as well. Centrifugal pumps are comparatively low price and easy to use and recently, are coming into wide use. However, the V-A pumping has many difficulties such as, for example, the incorporation of an artificial lung into the human blood circuit.  
           [0010]    Further, although the IABP has been widespread as a circulation assist device which is useful for acute myocardial infarction and acute heart failure subsequent to cardiac surgery operation, it has a problem in that the effect is pressure assist but not stream assist. For more serious heart failure which needs assisting the volume of stream, it is often the case that there is required an upper, powerful circulation assist means which uses such a pump as LVAD or PCPS.  
         SUMMARY OF THE INVENTION  
         [0011]    Accordingly, it is a primary object of the present invention to provide a circulation assist method and device capable of assisting the volume of blood stream in cooperation with the widespread IABP system during a heart surgery operation.  
           [0012]    Another object of the present invention is to provide a circulation assist method and device of the character set forth above which is easy to handle, simple in construction and low-priced.  
           [0013]    A further object of the present invention is to provide a circulation assist method and device which utilizes the expansion and contraction motion of a balloon of the widespread IABP system in making one-way stream of blood, in other words, which realizes assisting the volume of stream under the use of a pressure assist device by converting the motion of a balloon of the pressure assist device into the power source for pumping.  
           [0014]    An additional object of the present invention is to provide a blood stream control valve capable of streaming blood in a one-way direction, which valve is particularly designed for use in the circulation assist method according to the present invention.  
           [0015]    Briefly, according to the present invention, there is provided a circulation assist method which utilizes a balloon of an IABP system. The method comprises the steps of: providing a generally cylindrical pump chamber whose one and the other ends respectively communicate with an inflow hole and an outflow hole; providing an inflow valve for permitting blood to stream from the inflow hole into the pump chamber but for preventing the backward stream of blood; providing an outflow valve for permitting blood to stream from the pump chamber to the outflow hole but for preventing the backward stream of blood; connecting the inflow hole to a suction cannula which is inserted into and secured to the left atrium of a patient&#39;s heart; connecting the outflow hole to an ejection cannula which is inserted into and secured to the patient&#39;s aorta, thereby bypassing the left ventricle; fluid-tightly incorporating into the pump chamber a balloon portion of a balloon catheter of an IABP drive unit; connecting the balloon catheter to the IABP drive unit; and contracting and expanding the balloon with the timings determined based on trigger signals which a trigger circuit of the IABP drive unit selects from living body signals of the patient, so as to obtain one-way stream of blood.  
           [0016]    With this configuration, by using the pump chamber for incorporating therein the balloon of the balloon catheter and the inflow valve and the outflow valve in combination with the widespread IABP system, it can be realized to bypass the left ventricle with the blood stream being secured at a desired pressure and a required volume.  
           [0017]    In another aspect of the present invention, a cylindrical pump chamber is provided with one and the other ends thereof connected respectively to an inflow hole and an outflow hole. An inflow valve is provided for permitting blood to stream from the inflow hole into the pump chamber but for preventing the backward stream of blood, and an outflow valve is further provided for permitting blood to stream from the pump chamber to the outflow hole but for preventing the backward stream of blood. A balloon portion of a balloon catheter connected to an IABP drive unit is fluid-tightly incorporated into the pump chamber and is pulsated. The balloon in the pump chamber of the balloon catheter, when contracted, makes blood stream from the inflow hole into the pump chamber through the inflow valve and when expanded, makes blood stream out of the outflow hole through the outflow valve. Thus, by adding to the widespread IABR system, the pump chamber for incorporating the balloon of the balloon catheter and the inflow and outflow valves, it can be realized to provide a circulation assist device which is capable of assisting the stream of blood at a desired pressure as well as a required volume.  
           [0018]    In still another aspect of the invention, the pump chamber is provided at a straight portion of a J-shape cylindrical member and the inflow and outflow holes are provided respectively at the opposite ends of the cylindrical member. The balloon of the balloon catheter is fluid-tightly inserted from a bent portion of the J-shape cylindrical member into the pump chamber. Thus, only by adding to the widespread IABP system the J-shape cylindrical member provided with inflow and outflow valves, it can be realized to assist the stream of blood of a required volume at a desired pressure in the state that the blood stream is smooth and that there occur little hemolysis and little thrombus.  
           [0019]    In a further aspect of the present invention, the inner diameter of the pump chamber for containing the balloon is made the same to or slightly larger than the diameter of the balloon being expanded, and the length of the pump chamber is made as close to that of the balloon as possible so as to exclude any useless space as much as possible. Thus, in addition to the effects of claim 1 or 2, it becomes possible to reduce the volume of blood dwelling in the pump chamber to the minimum, whereby thrombosis can be prevented. Moreover, the pump chamber particularly designed to fit the size of the balloon can advantageously prevent the balloon which pulsates therein, from jumping with the motion as well as from vibrating undesirably.  
           [0020]    In a further aspect of the present invention, a ball valve in the inflow valve is moved along guide protrusions extending in the direction of blood stream within a valve chamber which communicates with the pump chamber at the side of the inflow hole. The ball valve prevents the backward stream from the pump chamber toward the inflow hole when seated on a valve seat formed in the valve chamber at the side of the inflow hole, and the moving end of the ball valve is confined by stop portions which are formed by raising the ends at the side of the pump chamber of the guide protrusions. Similarly, a ball valve in the outflow valve is moved along guide protrusions extending in the direction of blood stream within a valve chamber which communicates with the pump chamber at the outflow side. This ball valve prevents the backward stream from the outflow hole toward the pump chamber when seated on a valve seat formed at an outflow side of the pump chamber, and the moving end of the ball valve is confined by stop portions which are formed by raising the ends at the side of the outflow hole of the guide protrusions. With this configuration, there can be obtained inflow and outflow valves which are simple in construction, less-expensive, capable of restraining hemolysis and thrombosis to the minimum and the most suitable to a circulation assist means for assisting the stream of blood temporarily.  
           [0021]    In a still another aspect of the present invention, there is provided a blood stream control valve wherein a ball valve is movable along guide protrusions which extend in the axial direction thereof in a valve chamber. The ball valve prevents the backward stream from an outlet hole toward an inlet hole when seated on a valve seat, while it permits the stream from the inlet hole toward the outlet hole when leaving the valve seat. By raising the ends at the side of the outlet hole of the guide protrusions, stop portions are formed for confining the movable end of the ball valve. Thus, the blood stream control valve according to the present invention is simple in construction, low-priced and is capable of reducing hemolysis and thrombosis to the minimum.  
           [0022]    In a still further aspect of the present invention, there is provided a circulation assist device used in combination or cooperation with a widespread IABP system, comprising a generally cylindrical member which is formed with a pump chamber at its mid portion and provided with an inflow valve and an outflow valve at opposite end thereof. The cylindrical member is bent at a portion close to one end thereof to provide a hole through which a balloon of a balloon catheter connected to the IABP system is inserted fluid-tightly. The balloon is alternately contracted and expanded by a gas circuit of the IABP system. When contracted, the balloon opens the inflow valve and closes the outflow valve, while when expanded, it closes the inflow valve and opens the outflow valve. This causes blood to stream into the pump chamber when the balloon is contracted and blood to flow out from the pump chamber when the balloon is expanded. With this construction, since the pumping operation is effected using the contraction and expansion actions of the balloon of the balloon catheter, the assist device is quite simple in construction and reliable in operation since it does not require its own power source for operation.  
       
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0023]    The foregoing and other objects, features and many of attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description of the preferred embodiments when considered in connection with the accompanying drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and in which:  
         [0024]    [0024]FIG. 1 shows a sectional view of a circulation assist device utilizing a balloon of an IABP system, also illustrating the method of using the device;  
         [0025]    [0025]FIG. 2 shows an enlarged sectional view of an inflow valve;  
         [0026]    [0026]FIG. 3 shows an enlarged sectional view of an outflow valve,  
         [0027]    [0027]FIG. 4 shows a cross-section along the line  4 - 4  in FIG. 2, and  
         [0028]    [0028]FIG. 5 shows a section of a blood stream control valve. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    Referring now to FIG. 1, a numeral  10  denotes a drive unit for an IABP system and the unit  10  comprises a monitor  11 , a trigger circuit  12 , a positive/negative pressure generator  13 , and gas circuit  14 . The monitor  11  is connected to a detector such as an electrode  18  or the like which is affixed to a portion to be measured of a patient for taking living body signals, such as electrocardiogram, arterial blood pressure wave or the like. The trigger circuit  14  selects as trigger signals the R-wave of the electrocardiogram (electrocardiogram trigger) or the arterial blood pressure wave (arterial blood pressure trigger) and with a suitable time delay, controls the timings of the contraction and expansion of a balloon. A balloon catheter  15  connected to the IABP drive unit  10  is of the type that a slender balloon  17  is attached to an extreme end of a catheter  16 .  
         [0030]    A numeral  21  denotes a J-shape tubular or cylindrical member which constitutes a circulation assist device  20  utilizing the balloon  17  of an IABP system according to the present invention. The cylindrical member  21  is formed at its mid straight portion with a cylindrical pump chamber  22  for containing the balloon  17 , and at its end close to a bent portion, with an inflow hole  23  communicating with the inflow side of the pump chamber  22 . The cylindrical member  21  is further formed at the extreme end of its straight portion, with an outflow hole  24  communicating with the outlet side of the pump chamber  22 . At a portion close to the inflow hole  23 , there is provided an inflow valve  25  which permits blood to stream from the inflow hole  23  to the pump chamber  22  but prevents the adverse or backward stream, while at a portion close to the outflow hole  24 , there is provided an outflow valve  26  which permits blood to stream from the pump chamber  22  to the outflow hole  24  but prevents the backward stream.  
         [0031]    An inflow end member  27  is provided at the end of the inflow side of the J-shape cylindrical member  21  and is formed with a small diameter coupling section  28  connected to a suction cannula  52  and a large diameter valve section  29  containing an inflow valve  25 . Within the coupling section  28  and coaxially with the same, the inflow end member  27  is formed with an inflow hole  23  opening at one end thereof. In the inflow end member  27 , a valve chamber  30  larger in diameter than the inflow hole  23  and opening to the other end is formed coaxially within the valve section  29  and is in communication with the pump chamber  22  at the inflow hole side. A ball valve  31  contained in the valve chamber  30  is seated on a portion where the inflow hole  23  and the valve chamber  30  merge in the middle portion or the like of the inflow end member  27  so that a valve seat  32  is formed to prevent the backward stream from the pump chamber  22  toward the inflow hole  23 . For smooth stream of blood, the valve chamber  30  gently increases its diameter as it goes away from the valve seat  32 . At the inner surface of the valve chamber  30 , as shown in FIG. 2, guide protrusions of three or four streams whose top portions are circular in cross-section extend in the direction of blood stream so as to movably guide the ball valve  31  going away from the valve seat  32  in the direction of blood stream. Each of the guide protrusions  33  has a sufficient height from the bottom or inner surface of the valve chamber  30 , so that a larger cross-section area than the cross-section area of the inflow hole  23  can be secured between the ball valve  31  being away from the valve seat  23  and the bottom surface of the valve chamber  30 . Each protrusion  33  radially inwardly rises at its end close to the pump chamber  22  thereby to provide a stop portion  34  which confines the end in movement of the ball valve  31  toward the pump chamber  22 . Each stop portion  34  takes a streamline shape in section in the direction of blood stream, and the top of each stop portion  34  is independent of, or separated from, that of any other stop portions  34 , so that the blood stream within the inflow valve  25  is smooth and that there occur little hemolysis and little thrombus.  
         [0032]    The inflow end member  27  is made of polycarbonate resin by injection molding. The ball valve  31  made of solid silicon resin or the like is inserted into the valve chamber  30  from the side of the stop portions  34  by effecting slight elastic deformations on the stop portions  34  as well as the ball valve  31 . The outer surface of the coupling section  28  is formed with an inserting portion  35  and a male thread  36  for connection and screw engagement with a suction cannula  52  which has been inserted into and secured to the left artium of the patient&#39;s heart.  
         [0033]    A numeral  37  denotes an outflow end member provided at the end of an outflow hole side of the J-shape cylindrical member  21 . The end member  37  is formed with a small diameter coupling section  38  connected to an ejection cannula  53  and a large diameter valve section  39  containing an outflow valve  26 . In the outflow end member  37 , an outflow hole  24  opening at one end is formed coaxially within the coupling section  38 , and a valve chamber  40  larger in diameter than the outflow hole  24  and opening at the other end is formed coaxially within the valve section  39  and is in communication with the outflow hole side of the pump chamber  22 . A ball valve  41  contained in the valve chamber  40  is seated on an end close to the pump chamber  22  of the valve chamber  40 , so that a valve seat  42  is formed for preventing the backward stream from the outflow hole  24  toward the pump chamber  22 . For smooth stream of blood, the valve chamber  40  gently increases its diameter as it goes away from the valve seat  42 . At the inner surface of the valve chamber  40 , as best shown in FIG. 3, like the inflow valve  25 , guide protrusions  43  of three or four streams whose top portions are semicircular in cross-section extend in the direction of blood stream so as to movably guide the ball valve  41  being away from the valve seat  42 , in the direction of blood stream. Each of the guide protrusions  43  has a sufficient height from the bottom or inner surface of the valve chamber  40 , so that a larger cross-section stream area than the stream area of the outflow hole  24  can be secured between the ball valve  41  being away from the valve seat  42  and the bottom surface of the valve chamber  40 . Each protrusion  43  radially inwardly rises at its end close to the outflow hole  24  thereby to provide a stop portion  44  which confines the end in movement of the ball valve  41  toward the outflow hole  24 . Each stop portion  44  takes a streamline shape in the direction of blood stream and the top of each stop portion  44  is independent of, or separated from, that of any other stop portions  44 , so that the blood stream within the outflow valve  26  is smooth and that there occur little hemolysis and little thrombus.  
         [0034]    The coupling section  38  and the valve section  39  of the outflow end member  37  are made separately by injection molding. The ball valve  41  made of solid silicon resin is inserted into the valve chamber  40  from the side of the stop portions  44  by effecting slight elastic deformations on the stop portions  44  and the ball valve  41 . Thereafter, the sections  38  and  39  are united with each other at their end surfaces by melting joint or with a bonding agent of hot melt type. The outer surface of the coupling section  28  is formed with an inserting portion  45  and a male thread  46  for connection and screw engagement with the ejection cannula  53  which has been inserted into and secured to the patient&#39;s aorta.  
         [0035]    The cylindrical pump chamber section  47  formed with the pump chamber  22  of the J-shape cylindrical member  21  is made of polycarbonate resin or the like by squeeze molding and is bent to a J-shape at its inflow side. After the both ends of the pump chamber section  47  are heated to a softening temperature, the valve sections  29 ,  39  for the inflow and outflow end members  27 ,  37  are press-fit respectively into the softened ends of the bent and straight sections of the pump chamber section  47 , with the inner diameters of the bent and straight end sections being expanded to meet the outer diameters of the valve sections  29 ,  39 . After the press-fitting, the ends of the pump chamber section  47  are inwardly curved by being pressed on spherical outer surfaces of juncture portions between the valve sections  29 ,  39  and the coupling sections  28 ,  38 . Accordingly, the inflow and outflow end members  27 ,  37  are bodily secured to the both ends of the pump chamber section  47 , respectively. A suitable material for anti-thrombus is coated on those portions that get in touch with blood, such as inner surfaces of the inflow hole  23 , the outflow hole  24 , the valve chambers  30 ,  40  and the pump chamber  22  and outer surfaces of the ball valves  31 ,  41 .  
         [0036]    The balloon  17  of the balloon catheter  15  is inserted into the pump chamber  22  through an insertion hole  49  which opens at a boss portion  48  formed at the bent portion of the pump chamber section  47 . By threadedly tightening an annular seal member  50 , which the catheter  16  passes through, on the boss portion  48  through a gasket  51 , the catheter  16  fluid-tightly passes through the wall of the J-shape cylindrical member  21  to come out of the pump chamber  22  and is coupled to the IABP drive unit  10 . The inner diameter of the pump chamber  22  is made the same to or slightly larger than the outer diameter of the balloon  17  being expanded. The length of the pump chamber  22  is made slightly longer than that of the balloon  17 . Owing to these sizes so chosen, the volume of blood which dwells within the pump chamber  22  is reduced whereby the occurrence of thrombus can be prevented. Further, since the size of the pump chamber  22  is made to be approximately same to the size of the balloon  17 , it can be realized that while being pulsated, the balloon  17  is prevented from jumping and vibrating within the pump chamber  22 .  
         [0037]    A circulation assist method utilizing the balloon of the IABR system according to the present invention will be described together with the operation of the foregoing circulation assist device. The suction cannula  52  which has been inserted into and secured to the left atrium of a patient&#39;s heart is coupled to the inflow hole  23  provided on the J-shape cylindrical member  21 , while the ejection cannula  53  which has been inserted into and secured to the patient&#39;s aorta is coupled to the outflow hole  24 . The electrode  18  for taking an electrocardiogram is adhered to a suitable portion of the patient&#39;s body and is connected to the monitor  11  of the IABP drive unit  10 . The trigger circuit  12  selects the R-wave of the electrocardiogram (electrocardiogram trigger) as trigger signals and contracts and expands the balloon  17  at such timings that have a suitable delay from the trigger signals.  
         [0038]    Where the IABP system is employed as a circulation assist device for assisting the volume of blood stream, the balloon  17  is contracted for a contraction period of the heart cycle as the helium gas within the balloon  17  is discharged through the catheter  16  due to the negative pressure generated by the positive/negative pressure generator  13  of the IABP drive unit  10 . Thus, the pump chamber  22  increases its volume thereby to generate a negative pressure. This causes the ball valve  31  to open the valve seat  32 , whereby the blood streams from the left atrium into the pump chamber  22  through the suction cannula  52 , the inflow hole  23  and the inflow valve  25 . During this period, the ball valve  41  of the outflow valve  26  remains seated on the valve seat  42 , so that the backward stream of the blood from the outflow hole  24  toward the pump chamber  22  does not take place.  
         [0039]    For an expansion period of the heart cycle, on the other hand, the balloon  17  is expanded as being supplied with the helium gas from the gas circuit  14  of the IABP drive unit  10  through the catheter  16 . Thus, the pump chamber  22  reduces its volume to increase the pressure. This causes the ball valve  41  to open the valve seat  42 , whereby the blood is ejected into the patient&#39;s aorta through the valve chamber  40 , the outflow hole  24  and the ejection cannula  53 . During this period, the ball valve  31  remains seated on the valve seat  32 , so that the backward stream of blood from the pump chamber  22  into the inflow hole  23  does not take place. By contracting and expanding the balloon  17  having a capacity of 40 milliliters, a stream volume of 3.5 litters could be obtained with the peripheral pressure of a 50 mmHg and with the pulsation number of 70-90 BPM. Further, the effectiveness was confirmed through an experiment which used an experiment dog to measure the stream volume in the left heart bypass.  
         [0040]    Although in the aforementioned embodiment, the inflow and outflow end members  27 ,  37  bodily provided at the both ends of the J-shape cylindrical member  21  incorporate the inflow valve  25  and the outflow valve  26  therein respectively, a blood stream control valve  55  shown in FIG. 5 can be used in place of any of the inflow valve  25  and the outflow valve  26 . In this modified embodiment, a blood stream control valve  55  constituted independently of the cylindrical member  21  is coupled to the inflow hole  23  of the inflow end member  27  and another blood stream control vale  55  is coupled to the outflow hole  24  of the outflow end member  37 . A valve chamber  58  is formed in a valve center portion  57  of a valve chamber member  56  of the blood stream control valve  55 , and an inlet hole  61  and an outlet hole  62  both in communication with the valve chamber  58  are co-axially formed respectively at coupling sections  59 ,  60  protruding in opposite directions. A ball valve  63  contained in the valve chamber  58  is seated at an adjoining or juncture portion between the inlet hole  61  and the valve chamber  58 , thereby to form a valve seat  64  which prevents the backward stream of blood. For smooth stream of blood, the valve chamber  58  gently increases its diameter as it goes away from the valve seat  64 .  
         [0041]    Like the inflow valve  25 , at the inner surface of the valve chamber  58 , guide protrusions  65  of three or four streams whose top portions are semicircular in cross-section extend in the direction of blood stream so as to movably guide the ball valve  63  which is leaving the valve seat  64 , in the direction of blood stream. Each of the guide protrusions  65  has a sufficient height from the bottom or inner surface of the valve chamber  58 , so that a larger cross-section area for blood stream than the cross-section area of each of the inflow and outflow holes  61 ,  62  is secured between the ball valve  63  being away from the valve seat  64  and the bottom surface of the valve chamber  58 . Each protrusion  65  radially inwardly rises at its end close to the outflow hole  62  thereby to provide a stop portion  66  which confines the end in movement of the ball valve  63  toward the outflow hole  62 . Each stop portion  66  takes the shape of a streamline in the direction of blood stream, and the top of each stop portion  66  is independent of, or separated from, that of any other stop portions  66 , so that the blood stream within the blood stream control valve  55  is smooth and that there occur little hemolysis and little thrombus.  
         [0042]    The valve chamber member  56  is made of polycarbonate resin or the like by injection molding to form the inlet coupling section  59  and the valve section  57  bodily but the outlet coupling section  60  being separated. The ball valve  63  made of solid silicon resin or the like is inserted into the valve chamber  58  from the side of the stop portions  66  by making slight elastic deformations of the stop portions  66  as well as the ball valve  63 . Thereafter, the valve section  57  and the coupling section  60  are joined at their end surfaces by melting joint or with a bonding agent of hot-melt type. The outer surface of each of the coupling sections  59 ,  60  is formed with an inserting portion  67  and a male thread  68  for connection and screw engagement with a cannula, the circulation assist device or the like. A numeral  69  designates a reinforcing member made of polycarbonate resin or the like. This member  69 , after heated to a softening temperature, is press-fitted over the large diameter portions of the valve section  57  and the coupling sections  59 ,  60 . After press-fitting, the opposite ends of the reinforcing member  69  are inwardly curved along the spherical portions at respective junctures between the valve section  57  and the coupling sections  59 ,  60 . In particular, the reinforcing member  69  reinforces the juncture of the coupling portion  60  with the valve portion  57 .  
         [0043]    In the circulation assist device which utilizes the balloon of the IABP system according to the modified embodiment of the present invention, a pair of the blood stream control valves  55  are used as being connected as follows. That is, the suction cannula  52  which has been inserted into and secured to the left atrium of the patient&#39;s heart is connected to the inlet hole  61  of one of the blood stream control valves  55 , and the outlet hole  62  of the one valve  55  is connected with the inflow side of the pump chamber  22 . Further, the outflow side of the pump chamber  22  is connected with the inlet hole  61  of the other blood stream control valve  55 , and the ejection cannula  53  which has been inserted into and secured to the aorta is connected to the outlet hole  62  of the other stream control valve  55 .  
         [0044]    Prosthetic heart valve has been developed to replace the tricuspid, the pulmonary artery valve, the mitral valve and the aortic valve of the human heart. In fact, the prosthetic heart valve is intended to be transplanted in the human body, and thus, is made not only to prevent hemolysis and thrombosis but also to be so tough as to be durable for to-and-fro motions through several ten-millions, so that it cannot be help being expensive as a matter of course. However, it is too much quality and hence, unnecessary to use the prosthetic heart valve which is expensive and capable of transplanted into human body, as a circulation assist means which only needs to assist the blood stream for such a temporal period of time as long as twelve hours or at the most, twenty-four hours or so during a surgical operation for serious heart failure.  
         [0045]    To the contrary, the inflow valve  25 , the outflow valve  26  and the blood stream control valve  55  incorporate many features and advantages by being constructed as noted below. That is, the valve chambers  30 ,  40 ,  58  are provided in the form of monocoque in the valve sections  29 ,  39 ,  57  of the inflow end member  27 , the outflow end member  37  and the valve chamber member  56 , respectively. The guide protrusions  33 ,  43 ,  65  of three or four streams extend at the inner surfaces of the valve chambers  30 ,  40 ,  58  for guiding the ball valves  31 ,  41 ,  63 , respectively. The ball valves  31 ,  41 ,  63  are seated on or moved away from the valve seats  32 ,  42 ,  64  formed in the valve chambers  30 ,  40 ,  58 , respectively. Further, the guide protrusions  33 ,  43 ,  65  are formed smoothly, and the stop portions  34 ,  44 ,  66  are raised at one ends of the guide protrusions  33 ,  43 ,  65  for confining the ends in movement of the ball valves  31 ,  41 , 63 . The stop portions  34 ,  44 ,  66  are each separated at their top portions from others of the same valve chamber. With these features, the inflow valve  25 , the outflow valve  26  and the blood stream control valve  55  are capable of streaming blood smoothly within the valve chambers  30 ,  40 ,  58  thereby to reduce hemolysis and thrombosis to the minimum, are simple in construction and are low-priced, thereby being the most suitable to those valves for circulation assist means.  
         [0046]    Although in the above-described embodiments, the pump chamber section  47  is bent at its one end to form the J-shape cylindrical body  21 , it may otherwise be bent at its both ends to form a U-shape cylindrical member.  
         [0047]    Further, it is to be noted that the blood stream control valve  55  can be generally used as those which control one-way stream of blood, in addition to being used as the foregoing circulation assist device utilizing the balloon of the IABP system.  
         [0048]    Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.