Electrohydraulic heart with septum mounted pump

A total artificial heart for placement inside a living body comprising right and left ventricle enclosures, wherein each ventricle includes an exterior wall formed of (i) contacting wall structure and (ii) noncontacting wall structure which collectively enclose an interior volume comprised of a blood chamber and a pumping chamber. The contacting wall structure of each ventricle enclosure is configured for intercontacting relationship wherein the contacting walls of the respective ventricles form a septum which structurally separates the interior volume of the right ventricle from the interior volume of the left ventricle. The noncontacting wall structure comprises the remaining exterior wall of each ventricle enclosure. A fluid drive motor capable of reversible flow is positioned within and circumscribed by the septum and includes a flow channel therethrough which communicates between the respective pumping chambers of the right and left ventricle enclosures. A pumping fluid is contained within the pumping chambers and is responsive to the fluid drive motor to be reversibly transferred between the pumping chambers of the right and left ventricle to enlarge and contract the blood chamber and thereby simulate natural pumping action of the heart.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention pertains to total artificial hearts (TAH) which are self 
contained for permanent emplacement within a living being for total 
replacement of a natural heart. More particularly, this invention relates 
to a TAH which utilizes a hydraulic pumping system with a small, 
reversible pump to actuate pumping action. 
2. Prior Art 
Despite the climbing mortality rate of persons who die annually because of 
the limited supply of heart transplants, there are currently no commercial 
artificial hearts available for patient use. It is estimated that 35,000 
people per year in the United States alone need a replacement for the 
irreparable natural heart. Because only 2,000 donor hearts are available 
on the average, the vast majority (33,000) of these heart patients will 
die. By 1995, it is estimated that the target population for circulation 
support devices will be 60,300. Artificial Heart, Institute of Medicine, 
Jul. 23, 1991 (advance copy). 
Numerous patents have been issued which offer various technologies intended 
to address this critical need. These technologies extend from ventricle 
assist devices to the fully self contained TAH. U.S. Pat. No. 4,173,796 
issued to the present applicant in 1979 introduced the concept of a 
permanent electrohydraulic heart capable of being implanted within a 
living body with pumping support being provided by a reversible, electric 
impeller motor. The theory of operation for this device was to place the 
motor at the base of the TAH and reversibly transfer hydraulic pumping 
fluid between respective pumping chambers of the left and right 
ventricles. The motor was situated below the blood chambers and was 
separated by means of channels. 
Current commercial artificial heart devices are limited to air driven 
hearts whose cost approaches $100,000 per TAH and supporting air drive 
system, not counting associated medical fees for emplacement. Because of 
this high cost, each consideration of use of a TAH remains primarily a 
financial issue. Until such costs can be contained, it is apparent that 
artificial hearts will remain a theoretical solution to a real life 
problem. 
Numerous problems encumbered the intended success of the electrohydraulic 
heart invented by Jarvik and issued to the present applicant in the patent 
referenced above. The capacity of the motor was limited by its 
conventional design. Such design features included the concept of a 
central rotating shaft with attached impeller blades radiating outward 
from this shaft. The shaft was rotated by a brushless DC motor in a 
conventional manner. Fluid flow was advanced through an annular channel in 
a reversible manner, based on the direction of shaft rotation. 
Response time of the hydraulic fluid was not optimal. This was perhaps a 
byproduct of several design features. For example, the annular channel 
configuration imposed a substantial amount of surface area and frictional 
drag on the transferring fluid between pumping chambers of the respective 
ventricles. In addition to the drag induced by the large surface area of 
the flow channel within the motor, there was further drag developed by the 
substantial distance of travel required of the fluid as it moved from one 
pumping chamber to the other. This was a byproduct of the placement of the 
pump below the pumping chambers providing a flow channel to direct the 
flow between the left and right ventricles. Separate wall structure was 
provided below the septum to isolate the pump motor and define the 
described flow channel. Such a tortuous path for fluid movement which is 
being directionally reversed as much as 120 times per minute posed a major 
obstacle to confidence in the long term survivability of the TAH. 
What is needed is a greatly simplified hydraulic fluid transfer system 
which optimizes rates of fluid transfer and minimizes drag, without 
perpetuating the former high cost of production and emplacement. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a TAH which can be 
permanently implanted within a living body and capable of meeting the 
demands of blood circulation by simulation of pumping action provided by a 
natural heart. 
It is a further object of this invention to provide a TAH which is powered 
by an electrohydraulic fluid transfer system which minimizes the drag 
applied to the transferring fluid which reciprocates between the pumping 
chambers of the respective ventricles. 
A still further object of this invention is to minimize the fluid path 
displacement distance required of the reciprocating fluid, thereby 
maximizing work output of the drive motor. 
Yet another object of this invention is to provide a fluid drive motor 
which minimizes applied drag to the transferring fluid, as well as 
providing reduced wear to motor components. 
Other objects include the enhancement of valve components within the TAH 
for increasing flow efficiencies and improving blood compatibility of 
blood chambers by improving the seamless character of structural junctures 
of internal compartments within the TAH. Yet another object of the 
invention is to present a safeguard to excessive suction by providing an 
inward collapsible (but not distensible) wall section of the ventricle to 
compensate for the lessor cardiac output of the right ventricle compared 
the left. 
These and other objects are realized in a total artificial heart (TAH) for 
placement inside a living body, which comprises first and second ventricle 
enclosures operable as left and right ventricles, each ventricle enclosure 
having an exterior wall formed of (i) contacting wall structure and (ii) 
noncontacting wall structure which collectively encloses an interior 
volume comprised of a blood chamber and pumping chamber. The interior 
volume includes at least one pumping membrane sealed at an interior 
surface of the exterior wall and is configured to divide the blood chamber 
from the pumping chamber. The contacting wall structure of each ventricle 
enclosure is configured for intercontacting relationship wherein the 
contacting walls of the respective ventricles form a septum which 
structurally separates the interior volume of the first ventricle 
enclosure from the interior volume of the second ventricle enclosure. The 
noncontacting wall structure comprises the remaining exterior wall of each 
ventricle enclosure. Part of this non contracting wall chamber is soft and 
flexible but practically non distensible. If for some reason a pressure is 
generated inside the left ventricle which is lower than the environmental 
pressure inside the chest, then this part of the wall buckles in, thereby 
eliminating excessive suction which when transferred to the atrium might 
suck in the atrial wall which might occlude the aperture of the in flow 
valve. 
The pumping chamber of each ventricle is collectively enclosed by (i) at 
least a portion of the septum, (ii) the pumping membrane and (iii) any 
surrounding noncontacting wall structure. The blood chamber is enclosed by 
the pumping membrane on one side and the remaining exterior wall which is 
joined to the pumping membrane. Each blood chamber is provided with valved 
inlet and outlet means suitable for use in a TAH to enable unidirectional 
flow of blood through each ventricle in response to pumping action of the 
pumping membrane. A fluid drive motor capable of reversible flow is 
positioned within and circumscribed by the septum and includes a flow 
channel therethrough which communicates directly between the respective 
pumping chambers of the left and right ventricle enclosures. This improved 
position of the drive motor within the septum reduces the displacement 
distance of the reciprocating drive fluid, as well as drag forces 
attending such displacement. The result is a greatly enhanced efficiency 
which is complemented by a significant reduction in design complexity and 
attendant cost. 
Other design features include improved motor dynamics by elimination of a 
central drive shaft and enhanced flow rates through the drive motor, as 
well as improving valve design for unidirectional blood flow. 
Alternatively, a motor design with a central shaft may be used with the 
motor in the center and the impeller blades situated around the motor. 
Improved blood compatibility is achieved with new techniques of 
radio-frequency welding of polymer junctions in accordance with methods 
disclosed herein which enhance the seamless character of such junctures. 
Other objects and features will be apparent to those skilled in the art, 
based on the following detailed description, taken in combination with the 
accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 depicts a TAH having ventricle enclosures 10 and 11 operable as left 
and right ventricles in the TAH. Each ventricle enclosure has an exterior 
wall 13 formed of (i) contacting wall structure 14 and (ii) noncontacting 
wall structure 15, which collectively encloses an interior volume 
comprised of a blood chamber 16 and pumping chamber 17. This interior 
volume includes at least one pumping membrane 18 which is sealed at an 
interior surface 19 of the exterior wall 13 and is configured to divide 
said blood chamber 16 from said pumping chamber 17. 
The contacting wall structure 14 of each ventricle enclosure is configured 
for intercontacting relationship wherein the two contacting walls 14 form 
a single septum 14a which structurally separates the interior volume of 
the left ventricle enclosure from the interior volume of the right 
ventricle enclosure. Reference to contacting walls is accordingly intended 
to generally refer to the position where walls of the left and right 
ventricle join to form an opening 29 into which the drive motor is 
mounted. Although this septum has been described as the cooperation of two 
separate contacting walls 14, it could function equally well with a single 
wall of one of the ventricles which is sealed to the other ventricle, 
forming a common wall which could serve as the septum 14a. Therefore, as 
used herein, contacting walls may refer to a single, common wall which 
serves as a contacting wall from each attached ventricle enclosure, as 
well as the union of two separate walls in intercontacting relationship. 
As will be shown hereafter, the primary function of this septum from a 
perspective of the present invention is to physically support a fluid 
drive motor 30 which provides a flow path directly between the respective 
pumping chambers, thereby avoiding the need to channel pumping fluid 
around the septum. 
The noncontacting wall structure 15 generally refers to the remaining 
exterior wall of each ventricle enclosure. This includes the snout 20 and 
21 of each ventricle, as well as the remaining wall structure which is not 
forming part of the septum 14a. 
It will be noted that the pumping chamber 17 of each ventricle is enclosed 
by at least a portion of the septum 14a, along with the pumping membrane 
and any surrounding noncontacting wall structure. This chamber contains 
the pumping fluid, which may be an hydraulic fluid such as water, saline 
or methyl silicone. In accordance with conventional practice, the pumping 
fluid is forced between the respective pumping chambers of the left and 
right ventricles to alternately increase and decrease the volume of the 
blood chambers 16, thereby simulating the natural pumping action of a 
heart. 
The blood chamber 16 is enclosed by the pumping membrane on one side and 
the remaining exterior wall which is joined to the pumping membrane at 
juncture 28. In the illustrated embodiment, the blood chamber is actually 
contained within a sac-type structure which is inserted into the exterior 
wall of the ventricle which operates as a housing. The blood sac is a 
polyurethane composition formed of one or more layers of polyurethane. A 
particular embodiment was formed of two layers of 0.020 inches thickness 
of Pellethane which were thermo formed or molded over a mandrel. The 
resulting layers are 0.012 inches thick and are lubricated therebetween 
with graphite. It has been found that the flex life of two separated 
layers is greater than that of a single layer of heavier polyurethane. 
Other elastomers such as silicones may also be used. It can be seen from 
the right ventricle of FIG. 1 that the blood sac or chamber is sized to 
substantially fill the interior volume of the ventricle in diastole before 
the pumping fluid is forced to the opposing pumping chamber. It can also 
be seen that the blood sac or chamber is generally suspended within the 
pumping chamber, such as is illustrated by the left ventricle in FIG. 1. 
It is preferred to attach the outside wall 18 of the blood sac to the 
inside of the outer wall 13 of the pumping chamber. 
The upper portion of each ventricle, referred to as the snout, provides 
structural support for the valved inlets 40 and 43 and outlets 41 and 42 
suitable for use in a TAH to enable unidirectional flow of blood through 
each ventricle in response to pumping action of the pumping membrane. 
Although many valves are available for implementing the required 
unidirectional flow, the present inventors have developed an improved 
valve which provides enhanced response time to directional flow change. 
This valve is shown in FIG. 3. and comprises a bi-leaflet valve 44 wherein 
the leaflets 45 and 46 of the bi-leaflet valve are biased to a partially 
open position to thereby reduce the response time for opening of the valve 
means in response to blood flow. In the preferred embodiment of this 
disclosure, the leaflets 45 and 46 of the bi-leaflet valve include 
polarized magnets 47 and 48 which are positioned on opposing leaflets to 
create counter magnetic forces which urge the leaflets into a separated, 
open configuration. The amount of magnetic field is minimal and only need 
barely urge the respective leaflets to rest in a separated configuration. 
This slightly open configuration reduces the amount of inertia which the 
blood flow must overcome to open the valve. 
The subject bileaflet valve may be constructed of Isoplast (Trademark) or 
other stiff polymer material. Each leaflet is encased in a elastomer 
envelope such as polyurethane, which also serves as a hinge 49 and a hinge 
50 on the coaptation line. These leaflets are configured to open 
completely, so that they are outside the flow path of the bloodstream. As 
illustrated in the figure, a 40 degree movement is sufficient for this 
purpose. 
In the present TAH configuration traditional tri-semilunar valves are used 
in the aorta and in the pulmonary artery. Although they have three cusps 
the valve is sketched as a tricusp valve for clarity's sake. It has been 
discovered that matching of the properties of the three leaflets of the 
tricusp semilunar valves can be accomplished by the following unique 
procedure. Elastomer sheets to be processed through thermo forming are 
first extruded. Because there is molecular alignment in the direction of 
extrusion, the physical properties of each sheet are matched along the 
direction of extrusion. These three sheets are then superimposed along 
equal, separated orientations of 120 degrees, representing each of the 
three leaflets of the valve. When the sheets are subjected to the 
conventional thermo forming process, the respective leaflets are formed 
from the superimposed sheets to produce leaflets of equal thickness, 
flexion and identically oriented flex lines. 
This process is illustrated in FIGS. 9 and 10, wherein 10 mil sheets of 
Pellathane 80, 81, 82 were processed to form the tricusp valve 85. These 
sheets were oriented at 120 degree orientations 90, 91, and 92. The 
resulting valve 85 formed preserves the respective molecular orientations 
90, 91 and 92 with their attendant matched properties. Valve performance 
for each of the three leaflets was predictably uniform. 
Sinus valsalva are provided in the aorta or pulmonary artery and for the 
inflow valve in the ventricle. Actual placement of the valved inlet and 
outlet means is well known to those skilled in the art and need not 
presented in further detail. 
A primary feature of the present invention is utilization of a fluid drive 
motor 30 capable of reversible flow which can be positioned within and 
circumscribed by the septum 14a of the TAH. This drive motor includes a 
flow channel 31 which communicates between the respective pumping chambers 
17 of the left and right ventricle enclosures. It will be noted that the 
new positioning of the drive motor within the septum greatly reduces the 
displacement distance required for the pumping fluid. Use of the septum as 
a support structure for the drive motor eliminates the need for providing 
a flow channel for pumping fluid, thereby reducing drag arising from 
friction generated at the flow channel surface. 
The drive motor such as is manufactured by Sierracin/Magnedyne or other 
companies is generally configured as a round, flat structure with a 
diameter of 1.94 inches. A housing 32 contains stators on the periphery, 
with coils 33. An armature 34 and hydrodynamic bearing 35 are supported 
within the coils, and support the impeller assembly 36. The use of the 
hydrodynamic bearing 35 substantially eliminates wear within the system 
and supports the rotating impeller assembly which functions as the flow 
channel between the respective pumping chambers. A lateral thrust bearing 
38 is coupled to the housing 32 and maintains proper position of the 
impeller assembly within the hydrodynamic bearing. 
The armature and the stators of the motor are both imbedded in epoxy with 
the hydrodynamic bearing 35 in between. To accomplish this, first the 
exact dimensions of the parts are machined, then molds are made of these 
parts in room-temperature vulcanizing silicone. Finally the pats of the 
motor are placed in the molds and the molds are filled with a resin, under 
vacuum. 
As said above the fluids of the hydrodynamic bearing prevents the surfaces 
from touching and consequently there is no wear. Indeed the inventors have 
run these hydrodynamic bearings made of aluminum with water as lubricants 
and reversing as described without visible wear for six months. Epoxy 
bearings worked equally well. In the unlikely case that the fluid would be 
drained out the facing surfaces of the bearings are coated with two 
different polymers with low friction. The motor will be reversed in 
rotation 40 to 120 times per minute. The motor and impeller speed will be 
between 6,000 and 12,000 rpms, with greater speed toward the left 
ventricle than toward the right. The time required to switch from 
full-speed left to full-speed right will be about 14/1000 of a second. 
Because the motor will be in constant movement, the film of liquid on the 
hydrodynamic bearing will stay in tact, protecting the system from wear. 
The shroud for the impeller consists of the armature of the motor and has 
an approximate inner diameter of 1.0 inch. The impeller outer diameter 
likewise corresponds to the 1.0 inch dimension. There are 16 impeller 
blades of 0.225 inches in height and length, with a blade thickness of 
0.029 inches. Each blade is oriented at 45 degrees to provide maximum 
driving force in both forward and reverse directions. Although this 
describes the present impeller system, other configurations are also 
possible. For example, an alternative motor design is shown in FIG. 11. In 
this embodiment, the motor 100 is positioned at a central location, with 
the impeller blades 101 disposed around it. A surrounding shroud provides 
containment for the motor and impeller blades and is attached to a 
surrounding housing which contains the hydrodynamic bearing. These motors 
are also commercially available and fit well within the septum in a manner 
similar to the flat motor previously described. 
The motor will be controlled by an implantable box containing the required 
microcircuitry to operate the continuously reversing drive orientation. An 
exemplary diagram of this circuitry is shown in FIG. 7. Actual motor drive 
commands will be generated based on EMF feed back 38 and volume feedback 
39. This is similar to the control system used with the Jarvik 
hydro-electric heart disclosed in the referenced U.S. Patent. Other motor 
control systems may be applied and are well within the ability of those 
skilled in the art. 
It will be apparent that the transfer of equal volumes of pumping fluid 
between the pumping chambers of the respective ventricles will generate 
equal volumes of blood displacement. It is also well known that the volume 
of blood pumping by the left ventricle in a natural heart is greater than 
that pumped by the right ventricle. This is partly due to the bronchial 
circulation which empties into the pulmonary veins. Also, losses by 
extension under pressure and leaking of valves are greater on the higher 
pressure left than on the right side. This can be resolved by providing a 
small extension reservoir for hydraulic fluid on the right side or, by 
using a soft, inward flexible wall for the right ventricular housing as 
has been previously mentioned. A soft housing on either side will also 
help to prevent excessive suction and/or prevent sucking in of the atrial 
wall during diastole. 
The present invention offers numerous advantages over prior art TAH 
devices. Because it is a single unit, with a self contained drive motor, 
the total heart function can be placed within the living body, enabling 
total mobility. If the exterior wall is formed of a deformable, 
biocompatable polymer material which may be collapsed to a reduced size 
during implantation, implantation by the surgeon is much easier and less 
traumatic for surrounding tissue and organs. 
Operating efficiencies developed by the improved location of the pumping 
motor also reduce power requirements, as well as reduction in size. For 
example, whereas the prior art motors being utilized were as much as 74 mm 
in length, the current motor is only 7.6 mm. In addition, the weight of 
the new motor is only 85.7 gms, whereas the prior motors weighed as much 
as 350 gms. The volume of space taken by prior art motors based on the 
above factors was approximately 65 cc. The present motor requires only 
14.5 cc. 
Power is supplied to the drive motor by means of a transcutaneous power 
supply which transfers electrical power to the fluid drive motor without 
being in direct, electrical contact therewith. Such systems are now 
available or are under development and will be commercially available in 
the near future. 
The present invention also discloses the use of an air drive line 60 
coupled to each ventricle and being in direct fluid communication with the 
pumping chamber. Each air drive line includes a distal end (not shown) 
configured for placement near an epidermal layer of a host patient such 
that quick access is enabled to the respective air drive lines in the 
event of failure of the fluid drive motor. Initially, the air drive lines 
60 can be used to test the operation of the implanted TAH and insure that 
the system is totally functional. Once verified, the air lines may be used 
to fill the pumping chambers with hydraulic fluid for final preparations 
as an electrohydraulic heart. 
Each drive line includes means for sealing its distal end until direct 
access to the pumping chambers is required. These lines provide excellent 
conduit for exiting wires or leads attached to the drive motor, thereby 
avoiding the difficulty of breaching an otherwise sealed TAH housing. 
These electrical leads may be coupled at one end to the fluid drive motor 
and extend through at least one of the air drive lines to a subepidermal 
layer for electromotive interaction with the external, transcutaneous 
power supply. 
In connection with enhancement of blood compatibility of the blood chamber, 
the present invention provides for improved seamless surface character of 
the juncture of the blood sac with the housing. This is accomplished by 
use of radio frequency welding techniques disclosed in combination with 
the following method of fabrication of the TAH of the present invention. 
Specifically, this method comprises the steps of: 
forming first and second ventricle enclosures of biocompatable polymer in a 
configuration which enables the respective ventricles as left and right 
ventricles in the TAH with each ventricle enclosure having an exterior 
wall formed of (i) contacting wall structure and (ii) noncontacting wall 
structure which collectively encloses an interior volume comprised of a 
blood chamber and pumping chamber, said step including the forming of the 
interior volume by sealing at least one pumping membrane at an interior 
surface of the exterior wall so as to form a pumping chamber associated 
with the contacting wall structure and divided from the blood chamber; 
joining together the contacting wall structure of each ventricle enclosure 
in intercontacting relationship with the contacting walls of the 
respective ventricles forming a septum which structurally separates the 
pumping chamber of the first ventricle enclosure from the pumping chamber 
of the second ventricle enclosure; 
positioning fluid drive motor capable of reversible flow within the septum, 
with the fluid drive motor being circumscribed by the septum such that a 
flow channel through the fluid drive motor communicates between the 
respective pumping chambers of the first and second ventricles. 
The specific method for welding comprises the steps of preparing a 
conductive metal insert or part for positioning within the ventricle at a 
place where one or more sections have to be welded together. For example, 
a conductive piece of metal is made in a configuration which corresponds 
to the configuration of the final sealed perimeter, such as the juncture 
of the blood sac with the snout. A metal insert with a flat, smooth 
perimeter surface which operates as a mandrel for forming the final sealed 
perimeter as a seamless juncture is then prepared, along with a mating, 
exterior, conductive metal insert configured with a smooth interior 
opening which corresponds in shape to the configuration of the smooth 
perimeter of the first metal insert, but with a slightly larger diameter 
which leaves a uniform separation gap when inserted around the first metal 
insert which barely permits capture of the polymer materials to be sealed 
together therein. The remaining steps comprise: 
inserting the first metal insert within the ventricle or snout of the 
ventricle such that surrounding polymer material to be sealed is tightly 
drawn across the smooth perimeter of the first metal insert; 
positioning additional, surrounding ventricle material to be sealed to the 
polymer material which is already in position around the first metal 
insert such that the two materials are in overlapping relationship; 
inserting the first metal insert, with associated materials to be sealed, 
within the mating exterior metal insert such that the materials to be 
sealed are sandwiched between the opposing smooth faces of the mated metal 
inserts; and 
applying a high frequency, alternating current to the respective metal 
inserts sufficient to generate enough heat to fuse the respective 
materials sandwiched between the metal inserts into a seamless bond. 
By providing a slight taper to the flat, smooth perimeter, and a 
corresponding slight taper to the smooth interior opening, the first metal 
insert, having polymer material mounted thereon for sealing, cannot slide 
through the interior opening of the mating metal insert and the opposing 
smooth perimeter and interior opening are in approximate parallel 
orientation. This significantly simplifies the correct adjustment of the 
two mating members to a proper relationship. 
This procedures are illustrated by the graphic representation shown in FIG. 
8. The first metal insert 70 is placed in the snout 73 of each ventricle, 
with the polymer material 71 in surrounding orientation. The mating 
exterior metal insert 72 is configured as a split clamping ring and is 
positioned around the first metal insert with polymer material which is of 
a dielectric character. A high frequency of approximately 27 megahertz to 
40 megahertz alternating current is applied. The molecules begin to 
vibrate and produce the required heat to fuse the layers of ventricle and 
polymer together. The process takes about 20 seconds and produces a 
virtually seamless surface which greatly reduces likelihood of clotting. 
The procedure can be adapted to any configuration by merely fabricating 
the respective metal inserts into appropriate configurations. Rings of 
differing diameters could be used instead of the illustrated inserts. For 
example, FIG. 12 shows a graphic cross section of a ventricle housing 105 
which is being sealed to the peripheral edge of a diaphragm 106 and a base 
member 107. The respective peripheral edges of these members are blocked 
together between opposing rings 108 and 109, which are of brass 
composition and which are coupled to a radio frequency source. By applying 
the procedures indicated above and compressing the polymer materials of 
105, 106 and 107 between the respective rings 108 and 109, a smooth 
juncture and seal can be accomplished. This juncture greatly enhances 
blood compatibility and represents an inexpensive method of manufacture 
which can greatly reduce the cost of such artificial ventricles. 
Other variations will be noted with respect to the metal inserts or rings 
and which are within the ability of those skilled in the art to adapt to 
meet particular manufacturing requirements. For example, if the metal 
insert 70 is too large to be delivered through one of the valve openings 
at the snout it can be divided in two or more parts which can be 
disassembled before delivery through the opening. 
It is to be understood that the foregoing description of inventive features 
is merely exemplary. For example, the blood ports for in and out flow 
valves as described in connection with FIGS. 1 and 2 may be located 
directly in the blood chamber, rather than in the snout. Additionally, it 
has been discovered that the diaphragm configuration, such is shown at 
item 106 in FIG. 12, may be configured as a corrugated structure having 
many concentric rings which provide for enhanced extension during pumping 
action. Hatching marks 112 indicate the location for the RF seal which was 
applied by the respective rings 108 and 109 of FIG. 12. 
Those of ordinary skill in the art will appreciate that numerous additional 
variations may be made of the specific examples given. Accordingly, the 
scope the present invention is not to be limited by particular 
construction or method steps, but only by the following claims.