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This invention relates generally to connectors such as for use with a heart
assist apparatus and, more particularly, to an improved connector wherein
one connector member is permanently implanted in a patient having an
implanted heart assist apparatus and the other connector member is located
outside the body. When it is desired to utilize the heart assist
apparatus, the outside connector member and the implanted connector member
are interconnected.
The connector of the present invention includes at least two paths and in a
preferred embodiment at least one path is for the passage of electrical
signals and at least one path is for the passage of air under pressure.
When the heart assist apparatus is surgically implanted, electrodes are
sutured into the myocardium and signals from the human heart pass through
the implanted connector member to the external connector member and to a
driving unit such as that disclosed in U.S. Pat. No. 3,857,382 issued Dec.
31, 1974, and assigned to the assignee of the present invention. These
signals cause air under pressure to be pumped from outside the body
through the external connector member and through the internal or
implanted connector member to pump or drive the heart assist apparatus.
It may be appreciated that a significant problem in the use of implanted
heart assist devices will occur with respect to the physical interface
between the external apparatus and the implanted apparatus. Until an
intracorporeal power source is developed, it will be necessary to transmit
power through the skin. However, various problems have arisen with prior
connectors used to transmit power through the skin.
First, of course, it is necessary to have positive and exacting alignment
between the two connector members. Otherwise, there may be a leakage of
the pneumatic pressure, causing insufficient pressure to be transmitted to
the heart assist apparatus, and there may be an electrical shorting or
improper transmission of the electrical signals. Second, the two connector
members must be easily attachable since there is a strong psychological
impact on a cardiac patient who is "connecting himself" to his artificial
heart by joining the internal and external connector members. Furthermore,
many patients having implanted heart assist devices suffered varying
degrees of brain damage and resulting loss of muscular control from the
initial injury to the heart muscle.
Yet another catagory of problems with respect to implanted connector
members is the fact that infection frequently develops at the sight where
the connector passes through the skin which infection is compounded by
recurrent trauma of the wound caused by repeated excessive tension on the
implanted connector member.
Yet another problem is that the wires may become a pathway for fibrillating
currents to the myocardium.
Finally, in those patients who are not required to be on the artificial
heart assist apparatus 24 hours a day, it is necessary to provide a
suitable sealing device to permit the patients to engage in those
activities which his natural heart will permit and at the same time
preclude infection, dirt and the like from entering the implanted
connector member.
Thus, the present invention is directed to an improved connector which
overcomes each of the above problems.
SUMMARY OF THE INVENTION
The improved connector of the present invention includes two connector
members each having paths therein. Each connector member includes a
plurality of magnets arranged to generate spatially oriented magnetic
fields with the fields of one connector member being complementary to the
fields of the other connector member. When the two connector members are
moved toward each other, the complementary magnetic fields assure proper
alignment of the connector members, preclude misalignment, and maintain
the connector members together until a certain tension or pulling force is
reached. This pulling force necessary to separate the connector members is
below the pulling force necessary to injure the patient at the wound where
the implanted connector member passes through the skin.
In a preferred embodiment, three magnets are positioned 120.degree. apart
in each of the connector members. However, as will be explained, various
arrangements of magnets both in number and in symmetry are within the
spirit and scope of the present invention.
The complementary or attracting magnetic fields provide positive alignment
and do not require significant dexterity on the part of the patient. By
moving the connector members sufficiently close together to be within the
complementary magnetic fields, the actual mating of the connectors and
proper alignment of the paths in the connector members are accomplished
without any significant amount of control on the part of the patient. This
substantially reduces, if not eliminating completely, the psychological
effect of the patient "connecting himself" to his heart assist device.
A sealing cap is provided for each connector member when the connector
members are separated. This permits various activities to be engaged in by
the patient including swimming, taking baths and showers, etc., which
would normally be prohibited activities for a patient having an implanted
connector. Furthermore, the arrangement of the electrical wires in the
external connector permit these wires to be stretched between three and
five times its resting length without damage. This gives the patient a
certain degree of freedom of movement without putting excess tension on
the connector members or on the wound.
Finally, a mechanical interlock is provided between the two connector
members to prevent inadvertent separation of the connector members.
The connector of the present invention has been explained so far in the
context of an implantable connector member for use with an implanted heart
assist apparatus. However, many other uses are contemplated for a
connector operating according to the principles of the present invention.
For example, utilizing the principles of complementary spatially oriented
magnetic fields, any number of electrical and/or pneumatic paths may be
aligned and interconnected between connector members. Thus, a connector
manufactured according to the principles of the present invention may be
utilized in the "umbilical" of a space vehicle to connect an astronaut to
his supply of air and at the same time transmit electrical signals from
the astronaut's body back to the monitoring equipment.
Similarly, a connector according to the principles of the present invention
which is utilized to connect only electrical paths, may be utilized to
provide a constant charging to the battery of a vehicle when the vehicle
is parked. When the vehicle is started and pulled away, if the driver
forgets to first disconnect the external power to the battery, the present
connector provides for an easy release when the appropriate tension has
been reached. The use for battery charging is not restricted to electrical
vehicle such as golf carts, lawnmowers and the like, but may also be
utilized to charge batteries of emergency vehicles such as fire engines.
BRIEF DESCRIPTION OF THE DRAWINGS
The various objects, features, and benefits of the present invention,
together with other objects and advantages which may be attained by its
use, will become more apparent upon reading the following detailed
description taken in conjunction with the drawings.
In the drawings, wherein like reference numerals identify corresponding
parts;
FIG. 1 is a diagramatic illustration of the connector of the present
invention used with an implanted heart assist apparatus;
FIG. 2 is a view of the implanted connector member as seen in the plane of
arrows 2--2 of FIG. 1;
FIG. 3 is a broken away perspective illustration of the top connector
member made in accordance with the principles of the present invention;
FIG. 4 is a broken away perspective illustration of the bottom connector
member of the present invention;
FIG. 5 is an illustration of the winding of wires of the present invention
to provide for increasing the operating length of the wire;
FIG. 6 is a partially broken away perspective illustration of a sealing cap
according to the principals of the present invention; and
FIGS. 7-10 illustrate alternate embodiments of both the number of
electrical and pneumatic paths, and symmetry and asymmetry of the magnets,
as well as in the number of magnets.
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in FIG. 1, the connector 10 of the present invention
includes a top connector member 11 and a bottom connector member 12. Fluid
such as air from a fluid supply 13 through a conduit 14 of silicone rubber
or the like is coupled by the connector through an outlet conduit 15 to a
utilization device 16 such as a heart assist apparatus. Electrical signals
are coupled such as from the natural heart through an electrical path 17,
through the connector members and outwardly to an electrical control 18.
As shown in FIGS. 1 and 3, the electrical path from the top connector
member 11 may be inwardly of the conduit 14 for some distance before the
electrical path branches as at 19 to the electrical control.
As illustrated in FIG. 3, the top connector member 11 includes a outer
cylindrical shell 25 of Teflon brand of tetrafluoroethylene or
polypropylene or other material which is non-conductive to electricity and
non-magnetic. The shell 25 is a thin hollow shell having a closed bottom
and an open top.
Positioned within the shell 25 is a first path which in the preferred
embodiment is a centrally located fluid path 26 defined in part by a
non-magnetic stainless steel hollow sleeve or core 27 having a closed
bottom 28.
Symmetrically positioned around the sleeve 27 are three permanent magnets
30 which are preferably cylinders of samarium cobalt such as those
manufactured by the Raytheon Corporation. The magnets are symmetrical
relative to an axis through the sleeve 27, i.e., an axis perpendicular to
the open end of the connector member. A thin non-electrically conductive
material such as paper 31, which is porous so that it may be glued by
epoxy, is attached to each magnet 30. The insulating paper 31 is also
bonded to a ferrous disc 32 which connects the three magnets 30 together
and operates as a shorting bar to close one-half of the magnetic path and
thereby minimize air gaps between the magnets. Optionally, a plurality of
screws 33 are threaded through the closed bottom portion of the shell 25
and into contact with the shorting bar 32 to provide adjustment of the
shorting bar relative to the magnets. Moving the shorting bar away from
the magnets creates an air gap thereby increasing reluctance and reducing
the effective strength of the magnetic field. In a preferred embodiment,
the screws may be eliminated and the shorting bar, paper, and magnets are
all held together by an adhesive such as epoxy.
In the use of permanent magnets, it is very difficult to weld electrical
connectors to the magnets because the heat of welding damages the
permanent magnet. For this reason, thin terminals are bonded to each
magnet. Since, in a preferred embodiment, the magnets are circular in
cross-section as illustrated, these terminal plates are thin circular
plates 35 having a projecting tab 36 to which an electrical connection may
be easily welded. These plates are typically an iron-nickel alloy to
provide both electrical and magnetic conduction. Mounted on top of each
plate 35 is a cap 38 having sides 39 tapering to a smaller surface 40. In
the middle of each surface 40 is a projection 41. The caps and projections
are manufactured of a magnetic stainless steel and the cap, electrical
connecting plate and magnet 30 are assembled together by a conductive
epoxy which is an epoxy having silver particles therein. Once the magnet,
terminal plate and cap are secured together, the composite assembly
becomes, in broad terms, "the magnet."
The fluid path in the top connector extends from the stainless steel sleeve
27 radially outwardly through a suitable aperture in the shorting bar or
disc 32 to the conduit 14. A hollow metal or strong plastic conduit 45 is
inserted into a suitable radial aperture in the sleeve 27 and disc 32 to
prevent collapsing of the conduit 14.
Electrical paths are provided preferably through the magnets themselves.
Thus, as illustrated in FIG. 3, a wire 46 is illustrated as connected to
tab 36 of the plate 35 of one of the magnets 30. The connections to the
other two wires are not shown but the three wires are shown interiorly of
the conduit 14 and designated collectively by the numeral 19.
When the connector assembly has been completed, the disc 32, paper 31,
magnets 30 and electrical connecting plates 35 as well as the caps 38 are
encapsulated in a non-conductive epoxy 47. The epoxy is filled within the
shell 25 until only the surface 40 and projections 41 of each cap 38 are
exposed. The tapered surfaces or sides 39 thus provide an interlock with
the encapsulating epoxy to prevent the caps from pulling away from the
magnets 30. The outlet port of the sleeve 27, the top surfaces 40 of the
caps and the encapsulating epoxy define the first end or mating end of the
connector member.
One feature of the present invention is to provide freedom and flexibility
of movement of the top connector member 11 relative to the electrical and
fluid controls. Since the fluid conduit 14 is manufactured of silicone
rubber, there is a certain degree of stretching available. To permit
stretching of the electrical wires 19, I have found that I can initially
tightly wind these three wires in a helical fashion as illustrated in FIG.
5. In FIG. 5 the numbers 1,2,3, which are repeated, refer to each of the
wires making up the composite electrical wire 19. By tightly winding these
wires in a helical form initially, which is referred to as the rest
position, I have discovered that by exerting force in the direction of
arrows 48, I can stretch the wires from between 3 to 5 times their normal
length prior to fracturing the wires. This provides greater flexibility
and allows the patient to move without putting excess tension on the
surgically implanted connector member.
The wires are tightly fitted within an elastic tube which stretches as the
wires stretch and the resiliency of the tube restores the wires to their
tight helical form when tension on the wires and tube is released.
Mounted at the open end or outlet port of the sleeve 27 is a gasket or
O-ring 49 within a suitable shoulder or recess 50 in the sleeve 27. This
gasket 49 provides a fluid-tight seal when the two connector members are
attached together.
Referring now to FIG. 4, the bottom connector member 12 of the present
invention will be explained. The bottom connector member also includes a
teflon shell 25 having a peripheral flange or skirt 55 at the bottom end.
This skirt has a plurality of apertures 56 therethrough to facilitate the
growth of tissue and is covered on both sides with Dacron brand
polyethylene terephthalate with a velour weave, 57, to facilitate tissue
growth after transcutaneous implantation.
The components of the top connector member 11 and the bottom connector
member 12 are basically similar except for the following differences which
will be pointed out.
The central conduit or fluid path of the bottom connector member 12 is in
the form of a non-magnetic stainless steel elbow 60 providing a fluid
passageway 26 from the top of the connector member 12 through the shell 25
to the open bottom of the shell and to the utilization device such as the
heart assist apparatus. It is noted that both ends, top and bottom, of the
shell 25 of the bottom connector member 12 are open. Another difference in
the bottom connector member 12 is suitably encapsulated electronic
limiting circuitry collectively referred to as 65 which circuitry has
bottom terminal posts 66 to which the electrical connections are provided.
For the purpose of an implanted connector for utilization with a heart
assist apparatus, the electronic circuitry 65 is a current limiting
circuitry manufactured by Instrutek Incorporated of Annapolis, Maryland
which limits the current to 10 microamps. Obviously, limiting circuitry
can be provided in either or both of the connector members. A wire 67
connects one of the tabs 36 on a connector plate 35 to the limiting
circuitry 65; the other connections to the limiting circuitry and the
connections from the limiting circuitry are not illustrated because of the
broken away or diagrammatic view of FIG. 4.
In the use of a three wire system where one wire is grounded, the grounding
feature may be accomplished in one of two fashions. Either a third wire
may be introduced directly into the limiting circuitry 65 or,
alternatively, the stainless steel non-magnetic elbow 60 may serve as a
ground connection. If this is done, then one of the tabs 36 from a
terminal plate 35 must be bent to contact the elbow 60 as at 68 and a
similar contact in the top connector member 11 must be made.
Yet another important change or difference between the top connector member
11 and the bottom connector member 12 is that in lieu of projections 41 on
the flat surface 40 of the caps 38, there are indentations 70. These
indentations receive the projections 41 from the caps 38 of the top member
11 when the two connector members are attached together. This prevents the
two connector members from being separated by relative sliding movement
unless the sliding movement is sufficient to overcome this mechanical
interlock.
Yet another difference is that the adjustment of the shorting disc or
shorting bar 32 is provided only in the top member because it is not
feasible to adjust the position of the bar or disc 32 in an implanted
member. However, if the connector is being used other than in an implanted
fashion, then of course adjustment screws 33 may be provided on both the
top and bottom connector members.
FIG. 6 illustrates a sealing cap 75 having an internal rubber gasket 76.
This cap is made of a magnetically permeable material such as magnetic
stainless steel and snaps over the top of the connector member in contact
with the surfaces 40 of the caps 38. The magnetic forces hold the cap 75
in place and the cap serves as a shorting bar for the magnetic field. The
gasket provides a tight seal to prevent water, dust, etc., from entering
the connector member. Thus a cap 75 may be placed over the implanted
connector member 12 and the patient may take a shower or go swimming.
Similarly, a cap may be placed over the top connector member 11 to prevent
foreign particles, from entering the fluid path 26.
When the two connector members 11, 12 are moved toward each other, the
magnetic fields cause the two connector members to be attracted to each
other. The magnetic force is sufficiently strong to slightly compress the
gasket 49 thus providing an air tight seal for the fluid path 26. The
projections 41 and corresponding indentations 70 on the caps 38 provide a
mechanical interlock to preclude sliding of the connector. The strength of
the samarium cobalt magnets requires about a ten pound force to remove the
two connector members. By adjusting the screws 33 to provide an air gap
between the disc 32 and the magnets 30 in the top connector member 11, a
lesser magnetic field is created and hence less force is required to
separate the two connector members. This is especially beneficial to
reduce trauma to the wound the first few days after implantation.
Now, with reference to FIGS. 2 and 7-10, various embodiments of the
invention will be illustrated. In FIG. 2, three magnets 30 are illustrated
120.degree. apart and a single fluid path 26 is illustrated centrally
located. Two of the magnets are oriented with their north poles upwardly
and the third magnet 30a has its south pole upwardly. The opposed
connector member would have the similar spatial orientation of the
magnets. i.e., 120.degree. apart, but with a complementary magnetic
polarity. That is, two magnets having their south pole contacting the caps
38 and the third magnet having its north pole contacting the cap 38. Based
upon these complementary configurations, the two connector members may
only be connected in a predetermined configuration.
The term "spatially oriented magnetic fields" is used generically to refer
to any and all combinations of magnetic fields and specific locations of
magnets, i.e., symmetrical and asymmetrical, which result in a maximum
magnetic attraction between connector members with the paths properly
aligned.
In the preferred embodiment of the invention, three magnets are utilized
because the surfaces of the three magnets define a single plane and thus
interconnection of the two connectors is actually the mating of two
planes. This reduces the tolerance on the relative heights of the caps and
sleeves. However, any number of magnets may be utilized. Similarly, any
number of electrical and/or fluidic paths may be aligned and connected
according to the principles of the present invention.
For example, FIG. 7 illustrates a shell 25 having two asymmetrical magnets
80,81 and a central fluid path 82. FIG. 8 illustrates shell 25 having two
magnets 84 and one magnet 85 which are not symmetrically arranged; shell
25 does not include any fluidic paths.
It should be understood that when we refer to the exposed magnets in FIGS.
7-10, we are actually referring to the top surfaces 40 of the stainless
steel magnetic caps 38 which are attached by epoxy to the terminal plates
and then to the tops of the magnets themselves.
FIG. 9 illustrates shell 25 having two magnets 86 and a third magnet 86a
and two fluidic paths 87,88. It is noted that the three magnets are
asymmetrical with respect to the central fluidic path 87. This asymmetry
itself is sufficient to provide proper alignment when the two connector
halves are moved toward each other. However, if desired, the polarity of
magnet 86a may be reversed with respect to the polarity of magnets 86,
then, as illustrated in FIG. 10, the opposite connector half would have
two magnets 86a complementary to the two magnets 86 of the connector half
of FIG. 9 and a third magnet 86 complementary to the magnet 86a of FIG. 9.
The foregoing is a complete description of the present invention. Many
changes and modifications may be made without departing from the spirit
and scope of the present invention. The invention, therefore, should be
limited only by the scope by the following claims.
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