US2917751A - Mechanical heart - Google Patents

Description

ecu 22, 1959 w, FRY EIAL MECHANICAL HEART 4 Sheets-Sheet 1 Filed April 10, 1956 R R MM m a N w f x L ww n A an Q k I N\ H w I L Q 137F227 fbr's MAL/AM :1 Her L A n Y R F Im W MECHANICAL HEART 4 Sheets-Sheet 2 Filed April 10, 1956 Dec. 22, 1959 w. J. FRY ETAL 2,917,751

MECHANICAL HEART Filed April 10, 1956 4 Sheets-Sheet 3 U 5% L T L. m Izzzrenfars M4414 d E'y fkwc/s d 5?) Dec. 22, 1959 J, Y ETAL MECHANICAL HEART 4 Sheets-Sheet 4 Filed April 10, 1956 IUVEHTUPE MLL/AM d fie) fZAA/c/S fkr United States Patent MECHANICAL HEART William J. Fry and Francis J. Fry, Champaign, 111., assignors to Interscience Research Corporation, Champaign, 111., a corporation of Illinois Application April 10, 1956, Serial No. 577,333

14 Claims. (Cl. 3-1) This invention relates to improvements in a mechanical heart, and more particularly to a mechanical heart designed and constructed for disposition inside the human body as a complete replacement of the human heart, although it is obvious that the invention may be used as a replacement for the heart of various other living creatures besides human beings, as will be apparent to one skilled in the art.

In the past, a number of types of so-called mechanical hearts have been developed, but in every instance of which we are aware these formerly known so-called mechanical hearts were sizable and bulky pieces of apparatus, much too large for incorporation in a human or animal body, and were used mainly for either experimental purposes or as a temporary expedient to carry on proper blood flow in the body of a patient undergoing surgery, especially heart surgery. In other instances, sections of main blood vessels have been removed from the human body and plastic replacements such as woven nylon tubes successfully substituted for the removed sections. In otherinstances, substitutions have been made for one or more heart valves. However, insofar as we are aware no attempt has ever been made to provide an actual substitute or replacement for the entire human or animal heait.

The value and importance of the instant invention may not yet be fully appreciated, but a large proportion of that value and importance can readily be understood by considering a patient fully or partially confined to a chair or bed by virtue of an ailing heart. That patient may undergo surgery (during which a so-called mechanical heart of the type heretofore known might be utilized to maintain proper blood flow) in which the patients heart would be completely removed, and the instant invention mounted inside the patients body as a replacement or substitute for the removed heart. that patient, whose span of life prior to the surgery was highly questionable and in any event of relatively short duration, should assume a substantially normal as well as active life, not only of an ambulatory character but even to the extent of participating in physical sports and games, and maintain that active life for an indefinite period. In other words, the instant invention is designed to indefinitely prolong the lives of patients, human or animal, which would otherwise be materially foreshortened by virtue of heart trouble.

Over and above these advantages of prolonging the life of a patient, and rendering an inactive patient ambulatory and active, the instant invention may possess other unexpected advantages. For example, the ill effects of high or low blood pressure cannot be overcome by any adjustment made to a human heart. But with a mechanical heart incorporating a speed control, some definite and positive control over blood pressure may be maintained. With the aid of such control, many of the ultimate and sometimes disastrous effects of high and low blood pressure, arteriosclerosis and similar afflictions may not only be controlled should they have already oc- Thereafter 2,917,751 Patented Dec. 22,- 1959 curred, but may be prevented from occurring should their occurrence appear imminent.

With the foregoing in mind, it is an important object of the instant invention to provide a mechanical heart capable of being mounted in the chest cavity of a human or animal as a total replacement for the original human or animal heart.

Also an object of this invention is the provision of a mechanical heart capable of functioning as a replacement or substitute for a human or animal heart, and which may be selectively varied in speed of operation by the user.

A further feature of the invention is the provision of a mechanical heart particularly designed to occupy a minimum space, and which is constructed for continual operation for an indefinitely long period of time.

It is also an object of this invention to provide a mechanical heart capable of functioning as a substitute for a human or animal heart so constructed that the blood never contacts any moving mechanism other than its own container within the heart, which container is made of material that is inert with respect to. blood and other body fluids.

It is also an object of this invention to provide a mechanical heart that may readily be substituted for a human or animal heart with all moving mechanical parts enclosed within a sealed casing, wherein internal pressure is maintained in equilibrium with the body pressure so as to avoid damage to the mechanism by way of a blow on the body of the user and to avoid malfunction as the hydrostatic pressure of the external environment changes.

Another object of the invention resides in the provision of a mechanical heart of the character set forth herein in which the mechanism is devoid of parts and pieces having relatively short-time fatigue characteristics, the mechanism being designed for long usage and constantly lubricated.

Still a further object of the invention is the provision of a mechanical heart of the character set forth herein in which all moving parts are sealed within a container either of or covered by material which is non-toxic and non-irritating to tLe human or animal body and inert with respect to body. fluids.

A further feature of the invention resides in the provision of a mechanical heart system for installation in the human or animal bocy, embodying a mechanical heart as such, with an electric motor for driving the heart contained within the heart casing, wires or conductors from the motor leading through the body to a source of energy carried on an external part of the body, all elements of the apparatus contained within the body being insulated or covered with material inert to body fluids.

Also a feature of the invention resides in the provision of a mechanical heart system for disposition in a human or animal body, and wherein all the essential drive mechanism for operating the mechanical heart per se is car ried by the user, internally or externally of the body.

It is also a feature of the invention to provide a mechanical heart for replacing a human or an animal heart and which is so constructed that regardless of the speed of operation, the blood flow through the human or animal is at no greater velocity than with the original human or animal heart.

Briefly, a preferred embodiment of the: instant invention comprises a sealed casing containing means defining collapsible and expansible chambers, valve arrangements being provided to selectively govern the entrance and exit of blood into and from these chambers. Suitable conduits extend through the sealed casing wall for connection to the major blood vessels of the body in a manner al.- ready known. The casing also contains drive means for successively collapsing and expanding the mechanical heart chambers in order to create an action akin to pumping to provide the essential movement of blood through the body. The drive mechanism is so dispersed relatively to the chambers, that the blood passing through the mechanical heart cannot come into contact with anything but the chamber defining means made of a material that is inert to all bodily fluids. The casing also contains fluid, such as a light oil, under pressure equilibrium with the body, so as to prevent damage to the casing by a blow on the body of the user and also to maintain constant lubrication of moving parts. The operation is maintained as simple as possible in order to avoid complicated mechanical movements or the use of materials having a definite fatigue point. Further, the instant mechanical heart may be constructed to incorporate a two chambered device, or if so desired, four or some other number of chambers might also be utilized. The sealed casing is preferably covered with an inert, nontoxic and non-irritating material such as a suitable plastic.

In designing and developing a mechanical heart which must function as a complete substitute for the human heart, many and various problems must be considered and appreciated. Some of these problems deal squarely with the provision of a mechanical structure simulating as nearly as possible the operation of the human or animal structure it replaced; but there are many additional problems concurrent with the provision of a mechanical device taking the place of a human organ.

Some of these other problems include ways and means of counteracting adverse effects of accidents, or psychopathic or psychological characteristics or impulses of the particular patient. For example, it is desirable that the power source be so arranged that the power can never 'be entirely turned Off but only down to a predetermined minimum which is sufficient to keep the mechanical heart operating at a speed to maintain life in the patient when the patient is at rest. This not only avoids accidental stopping of the mechanical heart, but also intentional stopping of the mechanical heart in the event the particular patient developed a suicidal impulse. Further, it is known that when a person is in a relaxed condition, the normal human heart energy output in pumping is equivalent to about one watt, whereas when the particular person is exercising or otherwise moving strenously, the pumping energy output may reach as much as ten watts. Consequently with a mechanical heart there must be ready means available for altering the speed of 'the heart in keeping with what the particular user intends to do. If the user intends to indulge in extreme exercise, the heart must be initially stepped up in speed, and likewise when the user relaxes, the speed should be appropriately cut down. Also, since the valves of the natural heart act quickly, or in a time of short duration compared to the time of one pumping cycle, in order to minimize backfiow, so the valves with the mechanical or artificial heart should also be controlled to act quickly in order to approximate the human heart in its functions. in addition, care must be exercised not to use springs or similar parts subject to fatigue, and in the event the mechanical heart is driven by an electrical motor, it is not desirable to utilize a motor having brushes inside the body, so means must be provided to permit the utilization of another type of motor, such as an induction motor. And, as stated above, extreme care must be exercised to eliminate any toxic or irritating reaction from any of the parts and the heart structure itself must be capable of being mounted within the thoracic or chest cavity of the user without discomfort, and preferably without any persistent feeling that the user may be carrying a little more weight than was the case theretofore within his body.

All of these factors, as well as many others, have been taken carefully into consideration and adequate compensation made in the provision of the instant invention.

While some of the more salient features, characteristics and advantages of the instant invention have been above pointed out, others will become apparent from the following disclosures, taken in conjunction with the accompanying drawings, in which Figure 1 is a diagrammatic illustration of a human body, with a mechanical heart and associated apparatus, embodying principles of the instant invention, shown associated therewith in operative position;

Figure 2 is a greatly enlarged fragmentary vertical sectional view, with parts shown in elevation, of the mechanical heart itself, this particular view being taken substantially as indicated by the line IIII of Fig. 3, looking in the direction of the arrows;

Figure 3 is also a vertical sectional view taken from a different angle, substantially as indicated by the line IIIIII of Fig. 2, again with parts shown in elevation;

Figure 4 is a plan sectional view through the mechanical heart itself, taken substantially as indicated by the section line IVIV of Fig. 3;

Figure 5 is an enlarged fragmentary vertical sectional view of the same general character and location as is the case with Fig. 2, but illustrating a mechanical heart having an increased number of chambers therein over the showing in Figs. 2, 3 and 4; and

Figure 6 is a transverse vertical sectional view, with parts shown in elevation, of the structure of Fig. 5 taken substantially as indicated by the section line VI-VI of Fig. 5.

As shown on the drawings:

Of course, one of the objects of the instant invention is the provision of a mechanical heart which approximates the size of a natural heart as closely as possible. Consequently, with the exception of Fig. 1, the disclosures in the drawings are intentionally exaggerated for purposes of clarity and are greater than the preferable size for body installation. Actually, the artificial or mechanical heart, in the event an electrical motor is utilized as the prime mover, may be slightly larger than the natural heart in order to provide adequate room for the motor and the operative connections between the motor and the collapsing and expanding heart chambers. However, it is desirable to maintain the entire artificial or mechanical heart sufliciently small that it -will readily fit in the location of the natural heart in the chest cavity without necessitating crowding of the lungs or causing any discomfort to the user. Under certain conditions it might be desirable to utilize a mechanical heart of such size that a lung must be removed in order to mount the heart within the chest cavity but that is something it is desired to avoid except under rare and special circumstances.

Furthermore, in the illustrated examples, the casing has been shaped merely to show the essential parts of the apparatus properly enclosed, with no special effort being taken to reduce the size of the casing to the minimum extent or to provide a special shape which may prove more desirable at some later time. As illustrated, all sharp corners on the casing have been eliminated to avoid irritation or overcrowding, and while it is intended that sharp corners remain eliminated, the casing may be given any suitable or desirable shape consistent with the disposition of the required mechanism therein.

In Fig. 1 we have illustrated diagrammatically a human body 1, with a mechanical heart, generally indicated by numeral 2, of the general structure of the heart shown in' Figs. 2, 3 and 4, mounted in operating position in the thoracic cavity of the body 1. The casing or housing of the mechanical heart 2 may be satisfactorily fastened onto the transverse processes of the thoracic vertebrae, with connections to the adjacent rib structure if so desired, and a lei-lateral fastening may be prefrable to assure adequate stability and comfort to the user. A mounting in this manner may readily be accomplished without overcrowding of either lung and in a valve remaining closed, then the next 10 opens the valve, and the valve stays open for the following 170 of rotation.

In order to effect suitable valve actuation, a link 38 is pivoted at one end, as indicated at 39, to the adjacent casing wall, the other end of this link being bifurcated and pivotally connected to the shaft of the cam follower 37. A second link as has one end received between the bifurcations of the link 38 and is also pivoted to the shaft of the cam follower 37. The other end of this link is pivotally connected as at 41 to the central portion of a transversely extending valve actuating bar 4.2. A pair of rods 43 and 44 a e rigidly secured to opposite ends of the actuating bar 42, and the other ends of these rods are firmly secured to a second valve actuating bar 45, and rods 43 and 44 passing through a cross support or shelf 46 fixedly mounted to the casing wall, as seen in Figs. 2 and 4. With reference to Fig. 2, it will be particularly noted that the actuating bar 42 controls the valve 27 of the diaphragm 21, while the actuating bar 45 controls the valve 32 of the diaphragm 29 At the other end of the casing, an identical valve actuating arrangement is provided, including a cam wheel 47, links 43 and t9, and valve actuating bars 59 and 51 for the valves 28 and 33, respectively. It is to be especially noted, however, that the valve actuating mechanism at this end of the casing is out of phase with that at the opposite end of the casing, so that when valves 23 and 33 are closed as seen in Fig. 2, valves 27 and 32 are open.

With the use of the linkages above described in the valve actuating assemblies, springs or other devices having a definite fatigue point are eliminated. Adequate lubrication is obtained when it is recalled that the entire inside of the casing, with the exception of the inside of the diaphragms 21 and 29, is filled with a liquid such as light oil in pressure equilibrium with the body. That liquid filling the casing obviously lubricates the various moving parts. Preferably, the entire external surface of the casing is also covered with a coating of a suitable inert plastic material, such for example as non-reacting polyethylene. Such coating of the external surface of the casing also insures the elimination of any rough spots, and adds to the comfort of theuser.

When the mechanical heart is installed in the body in place of the original human or animal heart, the casing of the mechanical heart may be satisfactorily fastened onto the transverse processes of the thoracic vertabra, and a bilateral fastening would appear to be desirable. If so needed, added securement could be made to the ribs. Such mounting of the mechanical heart might be accomplished in generally the same manner bone fractures in elderly people are corrected with the use of metal plates.

The operation of the instant invention is extremely simple and positive, duplicating the action of the original heart to a more than necessary extent. With reference now to Fig. 2, let it be assumed that the orifice tube 2.6 is connected to the blood vessel leading to the lungs or pulmonary artery, the orifice tube 31 is connected to the pulmonary vein which returns blood from the lungs, the orifice tube 30 is connected to the aorta supplying blood to the body, and the orifice tube 25 is connected in suitable manner to the superior and inferior vena cava returning blood from the body. Now with the mechanism seen in the position of Fig. 2, the diaphragm 29 is sub stantially in fully closed position for the heart chamber 34, and blood has been forced from this chamber 34 through the orifice tube 36 to the body. At the same time, the diaphragm 2.1 has been expanded, so that blood from the body is returning through the orifice tube 25 into the other heart chamber 22. In the next half revolution of the motor, valves 27 and 32 will be closed and valves 28 and 33 opened, and the movable plate 28 controlling the diaphragms will move upwardly as viewed in this figure. been returned from the body will be discharged through outlet tube 26 to the lungs, and at the same time blood will return from the lungs through the orifice tube 31 into the heart chamber 34 for distribution to the body at the next half cycle of operation. It will be noted that there is a slight difference between the action of a mechanical heart and the original human or animal heart, in that the original heart pumps blood to the lungs and to the body at the same time, by virtue of the four chambers in the original heart. However, the very slight difference in timing, usually less than one half second, in which blood is supplied only to the lungs, and then in the next half cycle of operation only to the body, in the mechanical heart, will provide no noticeable difference in the bodily functions of the user of the mechanical heart. During operation, there is no sharp bending of the diaphragms at any time, partially due to the internal and external liquid pressure on these diaphragms. The diaphragm and valve actuating mechanisms are extremely simple and positive in their action. Thus, there are substantially no parts that should become out of order for a considerable or indefinite length of time, and the use of the mechanical heart in lieu of the original heart should prolong the life of the user insofar as heart trouble is concerned for an indefinite span of years.

This is particularly true because no parts of the mecham'sm are so constructed that they are likely to get out of order. For example, each valve is preferably secured to its respective valve actuator bar in the same manner the diaphragm is secured to the casing and supporting plates. Likewise, the opposite side of the tubes 25 and 26 from the valve structure per se, are preferably secured to the transverse supporting elements 46. Thus, adjustment of parts is maintained throughout the mechanism, and the only variable that need be provided is in the speed of the motor.

The speed of operation of the mechanical heart is at least partially controlled by adjustment of the rheostat or equivalent element 8. It is well known that the natural heart pumps less blood during rest than during exercise, and accomplishes this by changing its frequency, or number of beats, and the blood output per beat. However, with a mechanical heart it appears more practical to vary only the pumping frequency and to keep the blood output per beat substantially constant. The low speed of the motor 7 is preferably approximately 40 to 60 r.p.m., and the motor speed may vary by a factor of 3 or 4, which is not a critical number. Thus the mechanical heart is given a reasonable range of operation, but the range is not quite as great as that of the natural heart from complete rest to very violent exercise. Nevertheless, it is a very simple expedient for the user when retiring for the night to turn the dial 8 to the low speed point, and whenever that user contemplates movement, light exercise, or even quite violent exercise, the speed may be accordingly adjusted just prior to or contemporaneously with the start of the intended action. quently, with the mechanical heart substituted for the natural heart, there is no reason why the user, who is confined to a state of substantial inactivity by virtue of a defect in the natural heart, cannot indulge himself at least in reasonable or moderate exercise, and no reason why the user could not assume his former duties in earn-r ing a livelihood.

The size of the mechanical heart hereinabove described may be slightly greater than that of the natural heart, by virtue of the addition of the motor, but should not be sufiiciently large to necessitate the removal of any other body organ to make room for it, and should not be sufficlently large to cause any discomfort to the user by virtue of objectionable contact with other parts of the body.

However, in some cases, a larger mechanical heart having at least four chambers, ratherthan twofmay be Thus, the blood in chamber 22 which has.

Consewithout any change in feeling that a user will not become accustomed to in a very short period of time.

In the illustrated embodiment of the instant invention, an electric motor is utilized as a prime mover. Consequently wires must pass from the motor in the casing to a source of power. In the illustrated instance, a battery box 3 may be banded to the upper thigh of the user as indicated at 4. Wires leading from the battery box, preferably in the form of a unitary cable 5, extend from the arificial or mechanical heart 2 between the layers of mediastinum through the muscles of the chest Wall and then between superficial and deep fascia along the lateral aspect of the flank into the inguinal region and emerge preferably below the inguinal line as indicated at the point 6. The compound cable 5 is, of course, preferably insulated and completely covered in the portions within the body with an inert material such as nylon. This material is non-toxic, non-irritating, and quite inert to all body fluids and tissues. As shown in the drawings, it is preferable that the orifice point 6 where the conductor enters the body is at a location relatively remote from the mechanical heart itself, so that if irritation should result at the orifice point to such an extent that correction is desired, that irritation may be corrected without danger, since it will not be located in a vulnerable place. If deemed necessary, the orifice point 6 may be substantially sealed around the cable 5, for example, with an impervious film of liquid plastic material such as that used for holding colostomy bags to the skin.

Within the casing 2 of the mechanical heart, the cable 5 connects with a prime mover such as an electric motor 7. This is preferably an induction motor, and the control box 3 attached externally to the users body preferably contains batteries for driving the motor, and a suitable converter to change the direct current from the battery to alternating current for the motor. This converter may be in the form of a vibrator or the equivalent. The control box 3 also contains a manual speed control for the motor as indicated at 8, and it is preferable that this speed control is so set that it can never be turned down sufficiently to stop the motor. Thus, by insuring that the motor always operates at a minimum speed, it is impossible to stop the motor accidentally, and it is equally impossible for the user, in a fit of melancholia or the like, to deliberately turn down the motor to the stopping point, or to a speed that would be dangerously low. An auxiliary internal energy storage unit would eliminate the possibility of stopping the motor by complete removal of the external unit.

The first illustrated embodiment of the instant invention, namely a two-chambered mechanical heart, is best seen in Figs. 2, 3 and 4. The casing 2 may be fabricated from a number of initially separate pieces, and all of these pieces are preferably welded together into an integral sealed whole, as indicated by reference numeral 9. The casing may be given any desirable shape, consistent with the accommodation of its operating contents, and all of the corners are preferably rounded as indicated at 10, and the end portion of the casing is preferably given a smooth dome-like shape as indicated at 11 in Fig. 3. The casing could be preferably made of stainless steel or some equivalent material having the requisite strength and is covered by a material neutral to body fluids and tissues. The cable 5 may preferably be sealed at its exit point in the casing by way of a bushing 12 (Fig. 2) of nylon or equivalently inert material.

Within the casing, a supporting platform 13 is secured to the opposed casing walls, and extends entirely across the width of the casing, but as seen in Fig. 2, this platform is of less length than the interior of the casing to allow space on each side thereof for operating mech anism. A suitable support 14 is mounted on the platform to carry the motor 7 which, as stated above, is preferably an induction motor to avoid the use of brushes in a 6 device mounted within the human body. The motor shaft 15 is preferably in the form of a crankshaft and rotates with the motor armature, gearing being eliminated in the preferable construction. On each side of the motor the shaft 15 is provided with a crank 16, both crank arrangements or assemblies being identical. Each crank 16 is disposed within a flattened loop portion 17 mounted on top and preferably integral with a transversely extending bar 18. From each bar 18 a pair of rods 19-19 extend, as seen best in Fig. 3, and these rods are firmly anchored to the bar 18. All four such rods 19 are securely anchored at their other ends to a movable plate 20, the rods passing through suitable openings in the supporting platform 13.

Secured to one face of the fixed platform 13 is one side of a diaphragm or envelope 21 made of any suitable plastic material, such for example as non-reacting polyethylene which defines a heart chamber 22. The opposite side of this diaphragm is secured to the movable plate 20, as best seen in Fig. 2. The diaphragm is secured to the respective plates in any suitable manner equivalent to heat sealing or vulcanization. The diaphragm is provided with inwardly extending folds 23 on opposite sides as seen in Fig. 2, and with outwardly extending folds 24 on the other two opposed sides as seen in Figs. 3 and 4, thus providing room for the actuating rods 19. In other words, the diaphragm is folded in substantially the same manner as the diaphragm of an accordion. At the inner side thereof, the diaphragm 21 is provided with opposed orifice tubes 25 and 26 extending out opposite end walls of the casing. These tubes are preferably flattened as seen in Fig. 3, and before exiting from the casing the tubes may be shaped round and after exiting from the casing they are attached to body blood vessels in a known manner. The orifice tubes are also preferably so sized that the blood flow therethrough will be at no greater velocity than that of the human or animal heart the instant invention replaces. It will be especially noted from the foregoing description, that the body blood does not contact any portion of the mechanical heart except the inside of the diaphragm, and the material of that diaphragm is, of course, inert to human and animal blood.

The orifice tubes 25 and 26 are each provided with a valve formation, 27 and 28 respectively. As seen in Fig. 2, the valve formation is preferably corrugated so as to avoid any extra tension or stretching on the diaphragm material when the valve is closed as seen at the righthand side of Fig. 2. In that figure, valve 27 is open and valve 28 is in closed position. Preferably, also, the valves 27 and 28 are made slightly thicker than the remaining portion of the diaphragm A second heart chamber is provided by way of a diaphragm 29, one side of which is secured to the opposite side of the movable plate 20, and the other side of which is secured to the inside of the adjacent casing end or bottom wall. This diaphragm is otherwise of the same construction as the diaphragm 21, and is provided with a pair of orifice tubes 30 and 31, each of which is equipped with a valve as above described, 32 and 33, respectively. In the instance of the showing in Fig. 2, the valve 32 is open while the valve 33 is closed. This diaphragm 29 defines interiorly thereof a heart chamber 34.

Suitable means are provided for successively opening and closing the respective valves in predetermined order. To this end, a cam wheel 35 is fixed to the end of the motor shaft outside the crank 16, and this cam wheel is provided with an internal cam track 36 in which a cam wheel or follower 37 is disposed. With reference to Fig. 3 it will be seen that the cam track 36 is so shaped as to provide quick opening and closing of the valves. Preferably this cam track is so made that approximately 10 of motor shaft rotation will provide the closing actlon, the next of angular rotation results deemed desirable, and in such event it is possible that a lung may have to be removed in order to make room for the larger mechanical heart. The removal of a lung may be desirable in the event the lung is also diseased, and the larger heart having four chambers more nearly approximates the precise action of the natural heart than does the two chamber heart hereinabove described. That is because with a four chambered heart, blood may be caused to flow into the lungs and into the body simultaneously as is the case with the natural heart.

To this end, we have illustrated a four chamber heart in Figs. and 6. In these figures, the motor and driving mechanism directly connected therewith is the same as above described, particularly down to and including the drive links 40 and 4% for the valve actuating means. The entire mechanism is also enclosed in a casing 2a which is of substantially the same construction as the casing 2, but obviously larger in size.

With reference now to Figs. 5 and 6, it will be seen that the rods 19a depending from the bars 18 connected with the cranks 16-16 of the motor shaft extend downwardly through the supporting platform 13, and have affixed thereto a movable diaphragm actuating plate 52, then extend freely through another plate 53 fixedly secured to the casing 2a, and terminate in fixed attachment to a second movable or diaphragm actuating plate 54.

A diaphragm 55 is attached to the underside of the platform 13 and the upper side of the movable plate 52 in the manner above described, and this particular diaphragm is provided with an orifice tube 56 valved as at 57 at one side, and an orifice tube 58 valved as at 59 on the opposite side, but it will be noted that the orifice tube 58 does not extend through the casing wall. This diaphragm defines a heart chamber 60 which for purposes of comparison may be assumed to correspond to the right auricle of the natural heart and the orifice tube 56 may be assumed to be properly connected with the superior and inferior vena cava and so admits blood from the body to the heart chamber 60.

Another diaphragm 61 is attached to the underside of the movable plate 52, and the upper side of the fixed plate 53. This diaphragm is provided with an orifice tube 62 extending through the casing wall and valved inside the casing as at 63, and on the opposite side with an orifice tube 64 valved as at 65 inside the casing. This diaphragm 61 defines a heart chamber 66 which may be said to correspond to the left ventricle of the natural heart with the orifice tube 62 being connected to the aorta to deliver blood from the chamber 66 to the body.

A third diaphragm 67 is secured to the underside of the fixed plate 53 and the upper side of the movable plate 54, and this diaphragm is provided with an orifice tube 68 at one side, valved as indicated at 69, and at the other side with an orifice tube 76 which is not valved, but which is preferably integral with the orifice tube 64 of the diaphragm 61, as clearly seen in the right hand lower portion of Fig. 5. Thus, in effect, the diaphragms 61 and 67 are of substantially one integral construction with the connection by way of the orifice tubes 64 and 70, although these diaphragms might be more practically made separate, and the connection established between the orifice tubes 64 and 76 after construction of the diaphragms. This diaphragm 67 defines a heart chamber 71 which may be said to correspond to the left auricle of the naturai heart, and the orifice tube 68 may be connected to the pulmonary vein to return blood from the lungs to the chamber 71.

A fourth diaphragm 72 is attached to the underside of the movable plate 54, and also to the inside of the adjacent casing wall. This diaphragm is provided with an orifice tube 73 valved as at 74, and on the other side with an orifice tube 75 having no valve, but which is preferably secured to the inside of the casing wall and connects directly with the orifice tube 58 of the diaphragm 55, inside the casing. This diaphragm 72 decycle of operation.

fines a heart chamber 77 which corresponds with the right ventricle of the natural heart, and the orifice tube 73 may be connected to the pulmonary artery of the body to deliver blood from the chamber 77 to the lungs.

In order to actuate the valves 57, 63, 69, and 74, the link 46 operated by the cam wheel 35 is connected with a valve actuating bar 78 and from that bar a pair of rods 79-79 depend, these rods carrying in the proper location other valve actuating bars 80, 81 and 82 for the valves 63, 69 and 74, respectively. Suitable transverse supporting elements 83 and 84 may be provided through which the rods 7979 freely pass, and it is to be presumed that the respective valves are fixedly secured to the respective valve actuating bars, and the adjacent sides of the respective diaphragms are secured to the supporting members 83 and 84, as explained in connection with the first modification of the invention.

For the valves 59 and 65 at the opposite side of the construction, the link 49 is connected to a valve actuating bar 85 from which a pair of rods 86 depend and are connected to a second valve actuator bar 87 for the valve 65. Here again suitable transverse supporting members 83 and 89 are disposed at judicious locations and con nected to the walls of the casing.

In operation this form of the invention is as simple, and equally as positive as the form previously described. Looking now at Fig. 5, it will be seen that the chambers 66 and 77 are substantially compressed, while the chambers 6!} and 71 are expanded. This particular situation may be said to correspond to the ventricular systole and auricular diastole of the natural heart. At this point, blood has been expelled through the orifice tube 73 t0 the lungs, and blood has been returned through the orifice tube 68 from the lungs into the chamber 71 corresponding to the left auricle of the natural heart; also, blood has been expelled from the chamber 66 (the left ventricle) through the orifice tube 62 to the body, and blood has been returned from the body through the orifice tube 56 into the chamber 66 corresponding to the right auricle of the natural heart. Valves 5? and 65 have been held closed during this operation period. Upon the return movement of the rods 19a-19a, however, the chamber 77 will be expanded and the chamber 71 compressed, and the chamber 66 will be expanded while the chamber 60 is compressed. During this operation, all the valves 57, 63, 69 and '74 will be closed, but the valves 59 and 65 on the opposite side of the structure will be opened. During this operation blood will be transferred from the chamber 60 or right auricle through the open valve 59 and cross connection 76 into the chamber 77 or right ventricle; and blood will be transferred from the chamber 71 through the open valve 65 into the chamber 66 for delivery to the body upon the next half The movement which is the reverse of the position of the parts seen in Fig. 5 might then be said to correspond to the auricular systole and ventricular diastole of the natural heart. Thus, it. can be seen that during one portion of the cycle, blood is moved simultaneously from the mechanical heart to the lungs and to the body of the user from the chambers corresponding to the right ventricle and left ventricle of the natural heart, respectively, and returned from the lungs and from the body to the chambers corresponding to the left auricle and right auricle, respectively. During the subsequent part of the cycle, the orifice tubes leading to the lungs and body are closed off, and blood is transferred from the auricular heart chambers to the respective ventricular heart chambers. It will be seen, therefore, that the operation of this form of mechanical heart is substantially the same as the operation of the natural heart it has replaced.

Other than the differences specifically set forth hereinabove, the structure, mounting, power connections, etc., of the four chambered heart is the same as the previously described two chambered heart. I i

From the foregoing, it is apparent that we have provided a mechanical heart of simple operation, positive action, small size, and long durability which may be effectively mounted in the chest of a patient in lieu of and as a substitute for a removed natural heart. The mechanical or artificial heart duplicates to a more than satisfactory extent the previous operation of the natural heart, and should prolong the life span of a heart victim indefinitely, at the same time permitting the patient to become definitely ambulatory to a far greater extent than was theretofore possible. It will further be noted that by judicious adjustment of the speed of the motor of the artificial heart, some positive control can be 'elfected over the body blood pressure whici in some cases. may be highly desirable and extremely beneficial to the patient. Further, the mechanical heart may obviously be manufactured at a reasonably economical figure and may be installed in the body of a patient with reasonable speed by a surgeon of substantially moderate skill and experience.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the owing for connection to natural blood vessels and having valve associated therewith and with the pumping mechanism for controlling the flow of blood, drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection.

2. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit Within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said mechanism inclu 'ng means ing separate heart chambers and r s to successively decrease and enlarge the eifective s i said chambers to successively pump blood from and admit blood to said chambers in predetermined order.

3. A mechanical heart as defined in claim 2 including valve actuating mechanism arranged for quickly opening and closing said valve means and maintaining the valve means in either position a longer time.

4. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said drive means comprising an electric motor and said power supply means comprising electric wires leading to a power source externally of the human within whom the mechanical heart serves as a substitute heart.

5. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural lood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, drive means in said casing to actuate said pumping mechanism, power supply means for .said drive means connected thereto through said casing, said casing being fully closed and also sealed around said tubes and power connection, and control means to vary the speed of said drive means in proportion to the activ ity of the human carrying the mechanical heart as a substitute.

6. A mechanical heart as defined in claim 5, wherein said control means includes a control box arranged to be worn externally by said human for ready access thereto.

7. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow or" blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said power supply means including conductive means of substantial length and arranged to exit from the body of the human at a point remote from said casing with a source of power connected thereto and arranged to be worn on the body of the human adjacent to said remote point.

8. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said pumping mechanism including a plurality of diaphragms defining heart chambers and said tubes being integral with the respective diaphragms.

9. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to .ctuate said pumping mechanism, power supply means for said drive means connected thereto through said casing and said casing being fully closed also sealed around said tubes and power connection, said casing having a fluid under balanced pressure with the body fluid of the human and sealed within the casing outside of said pumping mechanism.

10. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of asize to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart,

tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said pumping mechanism comprising a plurality of diaphragms defining heart chambers in said casing with which tubes connect, said diaphragms being secured externally thereof to all fixed and moving surfaces which they contact inside said casing.

11. A mechanical heart as defined in claim 8, wherein said diaphragms are marginally folded in the manner of the diaphragm of an accordion.

12. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood Vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said valve means including a corrugated valve formation on one side of each of said tubes and means to periodically close and open said tubes by compression and release of said valve formations.

13. A mechanical heart as defined in claim 12 wherein said valve formations are integral with the respective tubes and thicker than the remainder of the respective tube.

14. A mechanical heart to act as a permanent substitute for a natural heart, comprising a casing of a size to fit within the chest cavity of a human after removal of the natural heart, pumping mechanism in said casing to circulate blood in simulation of the natural heart, tubes extending through the casing for connection to natural blood vessels and having valve means associated therewith and with the pumping mechanism for controlling the flow of blood, and drive means in said casing to actuate said pumping mechanism, power supply means for said drive means connected thereto through said casing, and said casing being fully closed and also sealed around said tubes and power connection, said drive means comprising an electric motor of the induction type mounted fixedly within the casing and the power supply means including electric wires in an insulative conductor extending through a sealed opening through the casing and to a source of electrical energy externally of the body of the human, said pumping mechanism and said valve means including respective movable members drivingly connected to said motor and operable in predetermined sequential order.

References Cited in the file of this patent UNITED STATES PATENTS 1,988,624 Kipp Jan. 22, 1935 2,625,932 Salisbury Jan. 20, 1953 FOREIGN PATENTS 1,010,329 France Mar. 19, 1952 OTHER REFERENCES Surgery: volume 32, number 5, pages 803-804, November 1952. (Copy in Patent Ofiice Scientific Library.) Surgery: page 685, vol. 30, No. 4, October 1951. (Copy in Scientific Library.)

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