U.S. patent number 3,563,245 [Application Number 04/713,400] was granted by the patent office on 1971-02-16 for biologically implantable and energized power supply.
Invention is credited to Donald Neil McLean, Jacob Rosensweig, John Saunders.
United States Patent |
3,563,245 |
McLean , et al. |
February 16, 1971 |
BIOLOGICALLY IMPLANTABLE AND ENERGIZED POWER SUPPLY
Abstract
The disclosure relates to an electric generation system or
device which finds useful application in the power supply units of
totally implanted electronic devices such as heart pacemakers; it
is particularly intended as an advantageous alternative to limited
duration implantable power supplies generally used. The resulting
novel power supply unit utilizes fluid pressure transfer means for
tapping a small fraction of the energy derived from the muscular
contractions of the heart and transmitting same to a remotely
implanted generator wherein the tapped energy is converted to
electrical energy.
Inventors: |
McLean; Donald Neil (L'Orignal,
Ontario, CA), Rosensweig; Jacob (Cote St. Luc 29,
Quebec, CA), Saunders; John (East Hartford, CT) |
Family
ID: |
24865987 |
Appl.
No.: |
04/713,400 |
Filed: |
March 15, 1968 |
Current U.S.
Class: |
607/35 |
Current CPC
Class: |
H02K
35/06 (20130101); A61N 1/3785 (20130101); H02K
7/1892 (20130101); A61N 1/056 (20130101) |
Current International
Class: |
A61N
1/378 (20060101); A61N 1/05 (20060101); A61N
1/372 (20060101); H02K 35/06 (20060101); H02K
35/00 (20060101); H02K 7/18 (20060101); A61n
001/00 () |
Field of
Search: |
;128/419,419 (P)/
;128/423,424 ;310/36,37 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Myers et al. "American Journal of Medical Electronics" Oct--Dec,
1964, pp. 233--236, 128/419P.
|
Primary Examiner: Kamm; William E.
Claims
We claim:
1. A biologically implantable and energized power supply for
implanted electric and electronic devices, comprising:
a. Fluid pressure sensing means to be disposed inside a heart
ventricle for detecting fluid pressure variations therein;
b. an energy conversion unit to be disposed outside the heart;
c. fluid pressure transfer means connected to said fluid pressure
sensing means and to said energy conversion units; said energy
conversion unit comprising:
d. means for converting said fluid pressure variations into
reciprocal motion;
e. an electromagnetic generator having a reciprocally rotatable
armature;
f. means for communicating said reciprocal motion to the
reciprocally rotatable armature and thereby convert same therein to
corresponding alternating current pulses of electrical energy;
g. rectifier means connected to said electromagnetic generator for
rectification of said alternating current of electrical energy to
corresponding direct current pulses of electrical energy;
h. accumulator means connected to said rectifier means for storage
therein of the energy in said direct current pulses of electrical
energy; and
i. connector means connected to said accumulator means for
connection thereto of said implanted electric and electronic
devices.
2. A biologically implantable and energized power supply as claimed
in claim 1, wherein, collectively, said fluid pressure sensing
means, fluid pressure transfer means and, means for converting
fluid pressure variations into reciprocal motion, comprise a closed
fluid system which includes a pair of fluid filled expansible
bodies and a flexible tubular conduit connected to said expansible
bodies and extending between them.
3. A biologically implantable and energized power supply as claimed
in claim 2, wherein said closed fluid system is pneumatic.
4. A biologically implantable and energized power supply
comprising:
a. Fluid filled pressure sensing and transfer means consisting of a
first expansible chamber forming device adapted to be disposed
within a heart ventricle, a tubular member connected at one end to
said first expansible chamber forming device and adapted to extend
therefrom through at least one heart valve and to extend outwardly
toward a body a position remotely disposed with respect to the
heart, a second expansible chamber forming device is connected to
the other end of said tubular member;
b. said first and second chamber forming devices and tubular member
containing a pneumatic fluid;
c. means associated with said second expansible chamber forming
device whereby to convert expansions and contractions thereof into
corresponding reciprocal motion;
d. an electromagnetic generator;
e. mechanical means for applying said reciprocal motion to the
electromagnetic generator and cause generation thereby of a
corresponding alternating current of electricity;
f. rectifier means electrically connected to said generator for
effecting conversion of said alternating current of electricity
into a pulsed direct current of electricity;
g. capacitive means connected to said rectifier means for
accumulation and storage therein of said electricity; and
h. means for connection to said capacitive means of electrically
operating implanted devices.
5. A biologically implantable and energized power supply for
implanted power consuming devices comprising:
a. Detector means adapted to be disposed in the heart and whereby
to produce a pneumatic signal in response to the blood pressure
variations detected therein;
b. translation means adapted to be disposed outside the heart,
whereby to transform pneumatic pressure variations into reciprocal
motion;
c. tubular conduit means connecting said detector and translation
means for transmission therethrough of the pneumatic signal of and
from the detector to the translation means;
d. an electromagnetic generator having a reciprocally rotatable
armature;
e. mechanical means for communicating said reciprocal motion to
said armature and thereby cause generation of a correspondingly
pulsed alternative current of electrical energy;
f. rectifier means electrically connected to said electromagnetic
generator for converting the pulsed alternative current of
electrical energy to a similarly pulsed direct current of
electrical energy;
g. accumulator means electrically connected to said rectifier means
for storage therein of the energy from said pulsed direct current
of electrical energy; and
h. connector means on said accumulator means for connection thereto
thereby of said implanted power consuming devices.
6. A biologically implantable and energized power supply, as
claimed in claim 5, wherein the implanted power consuming device
connected to said accumulator is a cardiac pulse generator
wherefrom a pulsed electrical signal produced therein is directed
through an insulated electrical wire conductor to an electrode
adapted to be disposed inside the heart and, wherein said insulated
electrical wire conductor is disposed in and coextensive with the
said tubular conduit means.
Description
The invention relates to an improvement in biologically implantable
power supplies of the type commonly used in implanted electronic
devices, such as heart pacers which are also known and will be
referred to hereinafter as cardiac pulse generators or
Pacemakers.
The field of implantable medical electronics is relatively new; it
has already yielded some remarkable results and holds a promise for
much more. Outstanding among the achievements realized to date are
those relating to Pacemakers which have already provided life
saving relief to countless sufferers of Stokes-Adams disease by
artificially restoring the proper rhythmic stimulation to their
failing hearts.
Pioneering experiments in the field of Pacemaker technology were
carried out in or about the year 1952 jointly by Paul Zoll and a
team of engineers from the Electrondyne Company. The early
Pacemakers were externally worn and therefore quite uncomfortable
and bulky. It is generally recognized that the development of the
first internally worn of totally implanted Pacemakers took place in
or about the year 1960 and the credit therefor goes jointly to two
independent teams of investigators which included such outstanding
contributors as Wilson Greatbach, William H. Chardack, Adrian
Kantrowitz and many others. It is remarkable that most of the
advances realized to date have related directly to the development
of improvements in the electronic circuitry of the Pacemaker and
electrode systems.
Regardless of the inconveniences resulting therefrom, limited
duration batteries are still the basic component in every implanted
power supply unit. Although mercury cells are presently used in
most Pacemaker power supplies, these are still incapable of
supplying the required power for longer periods than 3 years. It is
the general practice to have the batteries replaced or replenished
every 2 years or so, which means that all users of implanted
Pacemakers have to live with the prospect of being subjected to a
minor but, nevertheless always hazardous power replenishment
surgery every second year or so for the rest of their lives. This
is definitely a most objectionable feature of existing
Pacemakers.
The power supply of the present invention is intended as a
substitute for the hitherto used battery powered type of power
supply; unlike the latter it is not an accumulator of all the
energy to be used over a lengthy period but a power supply which
borrows the necessary energy from the body and converts it into
electricity at a rate commensurate with the power demand of the
Pacemaker.
The power supply of the invention is an important step toward
restoring a sense of security and self-sufficiency to the user of a
Pacemaker or the like, in the sense that it liberates him from his
former near total life dependency and reliance on the good
condition of his implanted power supply and immediate availability
at all times of the required skills, facilities and materials for
the emergency performance of a replenishment surgery in case of a
sudden and unexpected battery failure.
The power supply of the invention works on the principle that the
muscular contractions and relaxations of the tissues of the heart
are reflected in pronounced rises and falls of the static blood
pressure within the ventricles thereof, so that the effect of these
pressure fluctuations detected within the ventricle and channeled
therefrom to the power supply wherein it is applied to an
appropriately designed electromechanical generator; a pulse of
electricity will result which can then be subjected to
rectification and accumulated for supplying the required power to
the Pacemaker proper or whatever implanted electronic device is
connected thereto. The generator used is one which readily lends
itself to realization in highly compact form. It presents only few
moving parts, the total displacement of each of which can be made
so minute as to be almost imperceptible; as a result, the generator
is relatively free from wear even after prolonged continuous use of
duration exceeding the normal remaining life expectancy of any
user. Furthermore, the generator exhibits an unusually high rate of
energy conversion efficiency, which means that it only requires to
draw infinitesimal energy from the heart in order to produce the
very small quantity of electricity needed for energizing a
Pacemaker or the like implanted electronic device connected
thereto.
A basic object of the present invention is to provide a
miniaturized electromagnetic generator sensitive to the motion of
cardiac contraction and arranged so that the electrical energy
generated will be stored in a capacitor for use in a Pacemaker to
produce the required rhythmic electric impulse or in other
implanted electronic devices. This electromagnetic
(electromechanical) generator according to the invention is adapted
to generate alternating potentials proportional to the time
rate-of-change of magnetic flux in a mechanically oscillating
system. To obtain sufficient voltage when operating slowly, the
moving armature must be arranged to snap completely over after part
of the stroke has been completed. A second power pulse occurs on
the return stroke. The generator can be properly matched to the
Pacemaker by adjustments of the number of turns and gauge of wire
on the coil. The efficiency is limited mechanically only by
frictional and spring hysteresis and electrically by
coil-resistance, magnetic hysteresis, and eddy current damping.
Further objects and advantages of the present invention will be
apparent from the following detailed description and drawings, in
which:
FIG. 1, in general, shows the manner in which the heart pacer
assembly is totally implanted in the human body and connected with
the heart;
FIG. 2, in detail, illustrates the heart pacer arrangement
according to the invention including its activating source in the
form of a pressure transducer buried in the heart; details are also
shown in this particular FIG. as to the mode of connecting the
heart pacer with the heart;
FIG. 3, in detail, shows the airtight housing or box in which the
heart pacer unit is fixedly secured;
FIG. 4, in detail, illustrates the basic operation principle of the
power generator according to the invention; and
FIG. 5, in detail, shows the complete and actual arrangement of the
heart pacer unit embodying the present invention.
Although it has been said that the power supply of the invention is
intended for use in combination with any implantable electronic
devices, throughout the disclosure hereinafter and in the drawings
reference is made, for convenience, to the particular combination
with a Pacemaker. It should be understood that the choice of the
particular combination does not restrict the scope of the invention
in that respect.
Referring now to the drawings, wherein like reference numerals are
used in the various areas to designate like parts, FIGS. 1 and 2,
in detail, show a Pacemaker assembly according to the invention,
generally indicated at 1 and, the manner in which this assembly is
totally implanted in the human body and connected to the heart
3.
As can be seen from FIG. 1, the heart pacer unit 1 is connected
with the heart 3 by means of a hollow, intravenous catheter tube 2,
made of any suitable material, such as for example plastic, via a
large vein 4, in this case the jugular vein. The tube 2, in this
instance, terminates in the right ventricle 5 of the heart 3, FIG.
2, and is, in that location, integrally attached to an intracardiac
pressure transducer 6 in the form of a small, compressible and
airtight balloon or bag filled with a predetermined amount of gas.
Run through the tube 2 is an electrical conductor 7 which with its
one end is connected to the unit 1 and with its other end to an
electrical contact point or electrode 8 provided at the tip of the
transducer 6 and arranged so that it touches the tissues of the
heart, FIG. 2, in order to periodically deliver the small
electrical heart pulse energizing impulses emanating from the pacer
unit 1.
The pacer unit 1, as shown in FIG. 2, in effect, constitutes the
combination of (a) a miniaturized electromechanical power generator
9 activated by an inflatable and deflatable mechanical pressure
transmitter device 10 coupled thereto and, (b) an electronic
cardiac Pacemaker (pulse generator) 11, known per se, connected to
the generator 9 via an AC-rectifier(s) 12 and a storage
capacitor(s) 13.
These individual devices (the power generator 9, the transmitter
device 10, the Pacemaker 11, the rectifier(s) 12 and, the
capacitor(s) 13 are assembled into one unit and housed in a
hermetically sealed casing 14 covered with a suitable biologically
acceptable encapsulating material (not shown), such as for example
silicon rubber; a material which, following implantation will not
be rejected by the body and constitutes appropriate insulation for
the pacer unit from the electrolytic fluids within the human
body.
Initially, before describing in more detail the devices embodying
the present invention as well as the more important aspects
thereof, it would be helpful to briefly consider their principles
of operation.
As is known, the heart forms a hollow, muscular organ that pumps
the blood by alternate contractions and relaxations to cause
circulation thereof through the body.
It is with the help of the alternate muscular contraction and
relaxation of the heart in conjunction with the transducer 6
inserted therein, that the pacer unit 1, permanently implanted and
disposed at any suitable and convenient location inside the human
body but remote from the heart, is powered to produce the rhythmic
electrical impulses which are fed back to the heart.
The transducer 6 serves a triple purpose, namely (a) it senses the
pressure inside the ventricle of the heart wherein it is lodged;
(b) it is sensitive to the myocardial activity in the heart; it
contracts and expands along with the contraction and dilation of
the heart whereby the gas inside the transducer is alternately
forced out of and sucked back into the transducer thereby, via the
tube 2, alternately inflating and deflating the bellow 10 which, in
turn, activates and deactivates the generator 9 which, as a result
thereof, generates the necessary electrical energy, in this case a
pulsed alternating current, of the required magnitude to power the
Pacemaker 11; (c) it forms a support for the electrode 8 connected
via the electrical conductor 7 in the tube 2, with the Pacemaker
11.
It will be understood that the ventricle pressures and variations
thereof are picked up by the transducer and pneumatically (the gas
in motion) transmitted, via the tube 2 is converted into mechanical
force by the bellow 10. This mechanical force is applied to the
armature A of the generator 9, which is adapted to convert this
mechanical energy into an alternating electric potential.
The alternating current generated is sequentially rectified,
regulated and stored and, periodically supplied to the Pacemaker 11
in order to produce pacing pulses (the heart stimulation charges)
which, rhythmically and at a predetermined rate, are transmitted to
the heart via the wire 7 and the contact point 8.
Detailed reference will now be made to the heart pacer unit and
more in particular to the exact manner in which the electric power
is generated.
The power generator assembly of FIG. 2, as also known in FIGS. 3
and 5, is seen to comprise the bellow 10, which may be provided
with a bias pressure injection and/or bleeding valve 16 for
regulating the amount of gas in the system (the transducer 6, the
tube 2 and the bellow 10), and at the other side is provided with
an opening 17 which, via an airtight joint comprising a metallic
stem 18, is connected to one side of the hollow tube 2.
Provided at the lower side of the bellow 10 is a disc 19 which,
when pressure is applied to the transmitter (i.e. when the
transducer is compressed), relays this pressure to the armature A
of the generator 9 via a leverage mechanism, generally indicated at
20, consisting of a compression spring 21 connected with its one
end inside the fixed upper part 22 of the generator 9 and with its
other end contacting disc 19 via a roller connection 23 provided to
prevent friction; connected to the roller connection 23 is a
leverage plate 25 pivotal between the brackets 20 and coupled to
the armature A via a link 26. Operation of this leverage mechanism
depends on the inflation and deflation of the bellow 10, i.e. when
the bellow is extended, the disc presses, against the compression
spring 21 and through the leverage action the armature A is caused
to assume position "UP," FIG. 4, and when the bellow is retracted,
the spring relaxes and the armature assumes position "DOWN," FIG.
4.
The armature A is rotatable inside the generator 9 such as around a
bronze blade spring 28, FIGS. 4 and 5. When pressure (P) from the
bellow 10 is applied to the armature A, FIG. 4, it moves and pivots
around axis B, of the hinge 28 through an arc of only a few degrees
between the magnetic pole pieces N and S in its forward stroke
toward the pole pieces of opposite polarity. When the armature is
slightly passed the neutral plane, midway between the pole pieces N
and S, it is attracted to the other pole pieces and snaps in its
new position to complete its forward stroke. The small displacement
of the armature is sufficient to cause a complete and rapid
reversal of the lines of force induces electric energy into the
coils L surrounding the armature. When the force at P, FIG. 4, is
removed due to deflation of the bellow 10, the armature snaps back
thereby again producing electric current on its backward stroke. In
this manner, we have a permanent source of pulsed AC
electricity.
The alternating current thus generated is applied via leads L.sub.1
and L.sub.2, FIGS. 2 and 5, to the rectifier 12 where it is
rectified and is subsequently stored in capacitor 13 from which the
input current for the Pacemaker is drawn.
Incorporated in the unit there may be a voltage regulator, not
shown, which would permit utilization of such a generator
maintaining the electric energy generated at a predetermined value
or varying it according to a predetermined plan.
As shown in FIGS. 2, 3 and 5, the power unit proper may be lodged
in a separate housing 29 consisting of the fluidtight combination
of a lid 30 secured to a case 31. The bellow or expansible chamber
10 is located at the underside of lid 30 and in communication
therethrough with the pneumatic system through tubular connection
17 therewith. There may also be provided a conduit 15 which is
closed by a self-sealing membrane or valve such as plug 16 of a
sealant grease or rubber of silicone in such manner that the bias
pressure of the gas within the system may be adjusted initially and
from time to time thereafter, by appropriate injection or removal
of gas such as through puncturing of the closure membrane 16 by
means of an hypodermic needle (not shown in the drawing) or the
like. It is contemplated that a conduit such as 15 could also be
used for connection to and with an automatic pressure monitoring
device which would include a compact reserve supply of the gas at
high pressure, to restore the bias pressure of the system.
The gas used as pressure vehicle in the pneumatic system is
preferably one of relatively high molecular weight in order to
lessen the effect of gas losses which can result from permeation
thereof through the system's boundary materials. Also, because
there is bound to be a degree of gas permeation, it is preferable
to select an inert gas or one which can be absorbed in the
bloodstream without ill effects.
If necessary, provisions can be made to lodge the
rectifier/capacitor unit (12 and 13) with the power generator unit
within the same cylindrical housing or box 29 so as to obtain one
solid and compact unit to which, via suitable input and output
leads or terminals, one or more implanted devices can be connected,
i.e. aside from activating a Pacemaker (as is presently the case)
the above-described power generator assembly can also be used to
power various other, totally implanted devices, such as bladder
stimulators, electrically activated artificial limbs, stimulators
of the carotid sinus nerve (in patients with uncontrollable
hypertension), telemeters for biological phenomena, as well as
numerous applications in biological investigations in space
research, etc.
It will be appreciated that the mode of supplying electrical
impulses to the heart is not just restricted to the one employed in
the embodiment described hereinbefore; it is for example possible
to conduct these pulses to the heart by means of a number of
electrodes set into the heart muscle or, by such an electrode and a
large indifferent or ground electrode, etc.
* * * * *