WO2000001306A1

WO2000001306A1 - Minimal invasive cardiac massage device

Info

Publication number: WO2000001306A1
Application number: PCT/IL1998/000318
Authority: WO
Inventors: Menachem Scher; Amnon Kritzman
Original assignee: Pulsecare Ltd.
Priority date: 1998-07-07
Filing date: 1998-07-07
Publication date: 2000-01-13
Also published as: AU8126898A

Abstract

A cardiac massage device (10) deployable by a minimal invasive procedure for applying pulsatory pressure to a ventricular wall of a heart includes an inflatable receptacle (12) deployable between a closed insertion state and an open state. The open state of the device is configured for substantially enveloping the ventricular portion of the heart. A plurality of support elements (14) are mechanically linked to the inflatable receptacle so as to deploy the inflatable receptacle to its open state. Preferably, the support elements are implemented as flexible rods resiliently biased to return to a pre-defined shape and a retaining mechanism (22) is provided. Also described is a deployment technique employing suction clamping and a two-stage trocar (40, 42).

Description

Minimal Invasive Cardiac Massage Device

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to devices for cardiac treatment, and more

particularly to a device for cardiac massage which can be positioned by a minimal

invasive procedure.

Various devices are known for cardiac massage. Examples are disclosed in

U.S. Patents Nos. 4,536,893 to Parravicini and 5,713,954 to Rosenberg et al. These

describe inflatable cup-shaped devices which are deployed around the heart. A

pulsating supply of fluid to the devices generates inward pressure on the

ventricular portion of the heart, thereby assisting the pumping action.

These devices are both designed for implantation during an open heart

surgery procedure. As a result, their use is limited to long term applications in

which the patient is in a sufficiently fit general state of health to be able to

withstand such a procedure. Furthermore, such implantable devices do not allow

sufficiently rapid deployment to be useful in cases for which cardiac assist must be

started very rapidly or for emergency applications such as Cardio-Pulmonary

Resuscitation (CPR) procedures where direct cardiac massage could be much more

effective than the conventional procedure of pressing on the rib cage.

A further shortcoming of the existing cardiac massage devices relates to the

manner of retaining the devices in position around the heart. It is important that the

device applies pressure only to the ventricular region of the heart. However, when

pressure is applied from a device surrounding only the lower part of the heart corresponding to the ventricular region, the shape and texture of the heart tends to

make it slip out of the device. To counter this tendency, the device of Parravicini

provides straps for wrapping around the root of the aorta and pulmonary artery.

This somewhat primitive fastening technique is, however, clearly limited to open

surgical procedures and may exert pressure on the aorta or atria.

There is therefore a need for a device for cardiac massage which may be

deployed rapidly in a minimal invasive procedure and which provides effective

retention of the device in position around the heart.

SUMMARY OF THE INVENTION

The present invention is a device for cardiac massage which can be

positioned by a minimal invasive procedure.

According to the teachings of the present invention there is provided, a

cardiac massage device deployable by a minimal invasive procedure for applying

pulsatory pressure to a ventricular wall of a heart, the device comprising: (a) an

inflatable receptacle deployable between a closed insertion state and an open state,

the open state being configured for substantially enveloping the ventricular portion

of the heart; and (b) a plurality of support elements mechanically linked to the

inflatable receptacle so as to deploy the inflatable receptacle to the open state.

According to a further feature of the present invention, the support elements

are implemented as flexible rods resiliently biased to return to a pre-defined shape.

According to a further feature of the present invention, there is also

provided an elongated hollow structure for storage and deployment of the device, the inflatable receptacle and the flexible rods being retractable within the elongated

hollow structure so as to confine the flexible rods to an initial state corresponding

to the closed insertion state of the inflatable receptacle, the flexible rods returning

to the pre-defined shape as they advance out from the elongated hollow structure.

According to a further feature of the present invention, the elongated hollow

structure forms a storage stage of a two-stage trocar, an insertion stage of the trocar

being configured for insertion through the skin of a patient as part of a minimal

invasive surgical procedure.

According to a further feature of the present invention, the insertion stage of

the trocar includes a curved hollow guide portion for insertion within the patient,

the curved hollow guide portion providing a turn angle of between about 15° and

about 30°.

According to a further feature of the present invention, there is also

provided a manually operable mechanism for displacing the inflatable receptacle

and the flexible rods along a length of the trocar.

According to a further feature of the present invention, there is also

provided a retaining mechanism associated with the inflatable receptacle and

configured for deploying around a superventricular portion of the heart so as to

retain the inflatable receptacle in a position enveloping the ventricular portion of

the heart.

According to a further feature of the present invention, the retaining

mechanism includes at least one drawstring mechanism. According to a further feature of the present invention, the at least one

drawstring mechanism is connected to the inflatable receptacle via a non-inflatable

web.

According to an alternative feature of the present invention, the retaining

mechanism includes at least one inflatable retaining element, the inflatable

retaining element and the inflatable receptacle being provided with independent

fluid supply conduits.

According to a further feature of the present invention, there is also

provided a retractable suction clamping system including: (a) a suction cup

deployed for suction clamping to the apex of the heart; and (b) an axially

displaceable tube forming a fluid connection with the suction cup, such that, when

the tube is displaced forward and suction is applied to the tube, the suction cup

clamps to the heart and, when the suction is released and the tube is displaced

rearwards, the suction cup is withdrawn from contact with the heart.

According to a further feature of the present invention, there is also

provided at least one electrode deployed on an inner surface of the inflatable

receptacle so as to contact the heart when the device is deployed.

There is also provided according to the teachings of the present invention, a

cardiac massage device deployable by a minimal invasive procedure for applying

inflatable receptacle for substantially enveloping the ventricular portion of the

heart, the inflatable receptacle being configured to exert pulsating pressure against

the ventricular wall in response to a pulsating fluid supply; and (b) a retaining mechanism associated with the inflatable receptacle and configured for deploying

around a superventricular portion of the heart so as to retain the inflatable

receptacle in a position substantially enveloping the ventricular portion of the

heart.

According to a further feature of the present invention, the retaining

mechanism includes at least one drawstring mechanism.

According to a further feature of the present invention, the at least one

web.

According to an alternative feature of the present invention, the retaining

mechanism includes at least one inflatable retaining element, the inflatable

retaining element and the inflatable receptacle being provided with independent

fluid supply conduits.

There is also provided according to the teachings of the present invention, a

method of minimal invasive deployment of a cardiac massage device around the

ventricular portion of the heart of a patient, the method comprising the steps of:

(a) introducing the device in a compact state through the pericardium in the region

near the diaphragm; and (b) opening the device to form a receptacle which

substantially envelopes the ventricular portion of the heart.

According to a further feature of the present invention, the opening of the

device occurs through a plurality of resiliently biased flexible rods deployed within

the device returning to a pre-defined shape. According to a further feature of the present invention, suction clamping is

also applied to the surface of the heart during deployment of the device, the suction

clamping being removed once the device is properly deployed.

According to a further feature of the present invention, a retaining

mechanism is deployed around a superventricular portion of the heart so as to

retain the receptacle in a position enveloping the ventricular portion of the heart.

According to a further feature of the present invention, the compact state

exhibits a maximum diameter of no more than about 4 cm and preferably between

about 1.5 and about 2.5 cm.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference

to the accompanying drawings, wherein:

FIG. 1 is a schematic isometric view of a device for cardiac massage,

constructed and operative according to the teachings of the present invention, ready

to be deployed;

FIG. 2 is a schematic isometric view of the device of Figure 1 in a deployed

state;

FIG. 3 is a schematic cross-sectional view through the deployed device of

Figure 2;

FIG. 4 is a schematic cross-sectional view through a base connector of the

device of Figure 2; FIG. 5 is a schematic isometric view of the device of Figure 2 engaged

around a heart;

FIG. 6 is a schematic isometric view of a two-stage trocar for use in

deploying the device of Figure 1;

FIG. 7 is a longitudinal cross-sectional view through the trocar of Figure 6

with the device of Figure 1 stored therein;

FIG. 8 is a schematic isometric view of the first stage of the trocar of Figure

6 with the device of Figure 1 in its deployed state;

FIGS. 9A-9D are schematic side views showing a sequence of stages during

blind deployment of the device of Figure 1 around a heart;

FIG. 10 is a schematic rear view of a first implementation of a retaining

mechanism for the device of Figure 1 employing a drawstring mechanism; and

FIG. 11 is a schematic isometric view of a second implementation of a

retaining mechanism for the device of Figure 1 employing an inflatable retaining

element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a device for cardiac massage which can be

positioned by a minimal invasive procedure.

The principles and operation of a device according to the present invention

may be better understood with reference to the drawings and the accompanying

description. Referring now to the drawings, Figures 1-5 show a cardiac massage device,

generally designated 10, constructed and operative according to the teachings of

the present invention, which is deployable by a minimal invasive procedure.

Device 10 is used to apply pulsatory pressure to a ventricular wall of a heart.

Generally speaking, cardiac massage device 10 includes an inflatable

receptacle 12 deployable between a closed insertion state (Figure 1) and an open

state (Figure 2), the open state being configured for substantially enveloping the

ventricular portion of the heart in a manner shown in Figure 5. A number of

support elements 14 are mechanically linked to inflatable receptacle 12 so as to

deploy the inflatable receptacle to its open state. Support elements 14 are

preferably implemented as flexible rods resiliently biased to return to a pre-defined

shape. These rods serve both to push forward the inflatable receptacle during

introduction of the device into a patient and to open it into a correctly positioned

and shaped configuration to substantially envelope the ventricular portion of the

heart within the pericardium.

In a preferred implementation, the configuration of rods 14 is chosen to

provide unguided deployment around the heart in a manner to be described below.

This allows "blind" insertion of the device by a minimal invasive procedure. The

term "blind" is used in this context to refer to a minimal invasive procedure

performed without simultaneous use of imaging techniques for positioning. The

minimal invasive nature of the deployment makes the use of the device practical

even with patients not sufficiently fit to undergo major surgery and minimizes the

trauma to the patient. The possibility of blind insertion renders the device rapidly deployable so that it can be used when cardiac assist must be rapidly begun or in

emergency procedures such as CPR.

It should be appreciated that the device of the present invention may be used

in a wide range of circumstances where cardiac assist is required. The device

generally serves a "bridge to recovery" or "bridge to surgery" role for periods

which may range from a matter of minutes or hours up to weeks or even several

months.

In keeping with the normal definitions of "minimal invasive" procedures,

the insertion state of device 10 preferably exhibits a maximum diameter of no more

than about 4 cm, and typically between about 1.5 and about 2.5 cm. This ensures

minimum possible trauma to the patient as a result of the procedure.

Turning now to the features of device 10 in more detail, inflatable

receptacle 12 includes at least one, and typically 4-8, inflatable chambers 16

extending along the length of receptacle 12. A preferred arrangement of these

chambers may be seen in Figure 3. The inner wall 18 of each chamber is elastically

stretchable while the outer wall 20 is relatively non-stretchable. These properties

may be achieved either by employing different materials for the inner and outer

walls or by making outer wall 20 relatively thick compared to inner wall 18. In

either case, the materials may readily be selected from a range of polymer

materials conventionally used for surgical devices. The result of these properties is

that, when chambers 16 are inflated, the primary effect is directed inward so as to

exert pressure on a part of the heart located within inflatable receptacle 12. It should be noted that chambers 16 may be commonly or independently

controlled. By way of example, in certain applications, assistance may be desired

exclusively, or primarily, for the left ventricle to prevent excess pressure to the

lungs. For such applications, a left/right subdivision of the fluid supply to

chambers 16 is required.

As already mentioned, support elements 14 are preferably implemented as

flexible rods which exhibit a "memory" for a predefined shape. Usually, at least

three rods, and typically between 4 and 8, are used to achieve the desired opening

action. The rods may be of metal or polymer material, or a combination thereof,

and may have any cross-sectional shape.

A number of possibilities exist for the positioning of rods 14. They may be

included within either inner wall 18 or outer wall 20, or may form part of the

interconnection between adjacent chambers 16 as shown here. A further possibility

is positioning of rods 14 within the volume contained by chambers 16. In all of

these cases, especially where rods 14 are made from metal, they are preferably

surrounded by a layer of polymer material to avoid direct contact between the rods

and body tissue.

A further feature of certain preferred embodiments of device 10 is the

provision of a retractable suction clamping system 44. Suction clamping system 44

is used to clamp device 10 temporarily in position relative to the heart during

deployment, then being released and retracted away from the heart once correct

positioning of receptacle 12 around the heart has been achieved. As may best be

seen by referring ahead to Figure 7, suction clamping system 44 includes a suction cup 46 mounted on the end of a tube 48 positioned axially within device 10 in its

storage state. Tube 48 is provided with both a suction connection and a mechanical

connection for displacing suction clamping system 44 axially. The operation of

suction clamping system 44 will be described below with reference to Figures 9A-

9D.

It is a particular feature of most preferred implementations of the present

invention that device 10 features a retaining mechanism 22 operable during a

minimal invasive procedure to retain inflatable receptacle 12 in a position

enveloping the ventricular portion of the heart. Retaining mechanism 22 is

configured to be deployed around a superventricular portion of the heart, i.e., a

portion of the heart lying above the ventricular portion, where the reduced diameter

of the heart allows secure retention as shown in Figure 5. At the same time, as

mentioned above, it is important that inflatable receptacle 12 does not exert

pressure on the atria. To this end, retaining mechanism 22 is preferably

mechanically linked to inflatable receptacle 12 via a non-inflatable web 24. The

word "web" is used herein to refer to any continuous or discontinuous flexible

layer which forms a mechanical link between retaining mechanism 22 and

inflatable receptacle 12. Typically, web 24 is implemented as a single layer

continuation of the outer walls of chambers 16. Details of two possible

implementations of retaining mechanism 22 will be described below with reference

to Figures 10 and 11.

Insertion and subsequent control of device 10 is controlled through a base

connector 26. Base connector 26 houses fluid supply conduits 28, as seen in Figure 4, which connect to the root of each inflatable chamber 16. These conduits

preferably have relatively large areas to minimize resistance for a pulsating fluid

supply. Base connector 26 additionally provides a mechanical connection to rods

14 and houses retaining mechanism connections 30.

Externally, base connector 26 preferably also has guide features such as

guide slots 32 for guiding the base connector in a straight path within a trocar tube

to be described below, and a projecting handle 34 which allows manual

displacement of device 10 along the trocar and provides one or more external fluid

connection port 36 as well as a retaining mechanism control 38.

Deployment of device 10 is preferably performed as a minimal invasive

procedure by use of a trocar. A preferred trocar design and other details of the

deployment procedure will now be described with reference to Figures 6-9.

Turning first to Figures 6 and 7, there is shown a two stage trocar made up

of an insertion stage 40 for insertion through a small incision and a storage stage

42. Second stage 42 has a substantially cylindrical form within which device 10

may be retracted, thereby confining device 10 to an initial closed insertion state as

shown in Figure 1. Handle 34 of base connector 26 projects through a longitudinal

slot 44 in second stage 42 to provide a manually operable slide for displacing

device 10 along the length of the trocar. At the same time, handle 34 provides

accessible connections for the various fluid, suction and mechanical connections

employed to deploy and operate device 10. Storage stage 42 is preferably attached

to insertion stage 40 through a clip-on connection 50 so as to be removable after

deployment and replaceable for withdrawal of the device. Insertion stage 40 preferably includes a curved hollow guide portion 52 for

insertion within the patient. Guide portion 52 is preferably formed with a turn

angle of between about 15° and about 30°, and typically about 20°. In other words,

guide portion 52 redirects device 10 during deployment by an angle of about 20°

from the extensional direction of storage stage 42. This provides the correct

alignment for deployment of the device curving under the sternum to an initial

position facing the apex of the heart. A shield 54 is preferably deployed around

insertion stage 40. This serves to delimit the fully inserted position of the trocar, as

well as providing a seal around the incision.

Figure 8 shows the deployed state of the device within insertion stage 40

after removal of storage stage 52. In this state, the part of the device projecting

from the body is small and can be secured by various techniques such as one or

more belt around the patient.

The procedure for deploying device 10 will now be described with reference

to Figures 9A-9D. Initially, insertions stage 40 is introduced through an incision in

the outer wall of the abdomen just below the sternum 55 and through a

corresponding incision through the lower part of the pericardium 56 in the region

near the diaphragm. At this stage, tube 48 is displaced forward and has suction

applied so that suction cup 46 clamps to the heart 58 at or near its apex. This

clamping effect maintains the spacial relation between the insertion stage 40 of the

trocar and the heart during the rest of the deployment procedure.

Then, handle 34 is gently eased forward along slot 44, thereby advancing

device 10 out through guide portion 52. As support elements 14 emerge, their resilient memory urges them to their predefined diverging form, thereby opening

inflatable receptacle 12 to its open form. The simultaneous advancing and opening

action brings the device through the stages shown in Figures 9B and 9C until it

substantially envelopes the ventricular portion of the heart. At the same time, the

distal part of retaining mechanism 22 and its associated non-inflatable web 24

extend over part of the superventricular portion of the heart, primarily on the dorsal

side which is not obstructed by blood vessels.

Once the device reaches its fully deployed state, retaining mechanism 22 is

tightened around the superventricular portion as shown in Figure 9D. This is

sufficient to firmly retain the heart within inflatable receptacle 12 without unduly

restricting the normal movement of the heart. The suction clamping is then

released and tube 48 withdrawn so that suction cup 46 has no effect on the

subsequent operation of the device.

It will be clear that removal of the device is achieved by a simple reversal of

the steps described, except that the suction clamping feature is superfluous during

removal. The resilient nature of support elements 14 provides an inherent self-

opening feature which facilitates opening of retaining mechanism 22.

Turning now briefly to Figure 10, this shows a first preferred

implementation of retaining mechanism 22. In this case, the tightening action is

achieved by a drawstring mechanism in which a draw-string or wire 60 extends

along a pair of sleeves 62 which extend up to near the opening of receptacle 12. In

this case retaining mechanism control 38 may be implemented as a simple manual or automated drawstring connection which pulls on the wire 60, thereby shortening

the circumference of the opening between the ends of sleeves 62.

An alternative implementation of retaining mechanism 22 is shown in

Figure 11. Here an inflatable collar 64 may be inflated through an independent

fluid supply conduit 66 to lodge against the superventricular portion of the heart.

Turning now briefly to the operation of deployed device 10, the device is

driven by a pulsed source of fluid, typically in the form of a pulsatile pump. In an

implementation for very short term emergency use, a manual hand pump may be

used. The operating fluid may be liquid, gas or a mixture thereof, and is preferably

sterile.

Timing of the pulses is preferably performed according to one of three

modes. Firstly, in a CPR case where unaided heart activity has stopped, pulses are

generated either manually or according to suitable pulse timing circuitry of any

kind. Secondly, where either a natural or induced heart beat is detectable, the

pulses are preferably synchronized with the heart, either through an

electrocardiogram (ECG) signal or by direct synchronization with a pacemaker or

defribulator. Details of how to achieve ECG synchronization may be found in a

number of sources such as the aforementioned U.S. Patent No. 5,713,954 to

Rosenberg et al. which is hereby incorporated by reference in its entirety. In a third

mode, the basic synchronization with an ECG signal is enhanced by closed loop

feedback. Suitable sources for feedback to provide a measure of the effectiveness

of the cardiac assist include, but are not limited to, measurements of the cardiac

output, the ejection fraction, or the systolic blood pressure. These quantities may be measured by any conventional techniques. Clearly, to implement these various

modes, suitable hardware or hardware/software combinations are provided. These

typically include a microprocessor unit operating appropriate software under a

suitable operating system as is well known in the art.

Finally, it should be appreciated that the device of the present invention may

be used to advantage in conjunction with a range of other devices and techniques.

Examples include, but are not limited to, use in combination with a pacemaker,

defribulator, ventilator systems or CPR systems. For such applications, one or

more electrodes 70 may be incorporated into the inner surface for inflatable

receptacle as shown schematically in Figure 3.

It will be appreciated that the above descriptions are intended only to serve

as examples, and that many other embodiments are possible within the spirit and

the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A cardiac massage device deployable by a minimal invasive

procedure for applying pulsatory pressure to a ventricular wall of a heart, the

device comprising:

(a) an inflatable receptacle deployable between a closed insertion state

and an open state, said open state being configured for substantially

enveloping the ventricular portion of the heart; and

(b) a plurality of support elements mechanically linked to said inflatable

receptacle so as to deploy said inflatable receptacle to said open state.

2. The device of claim 1, wherein said support elements are

implemented as flexible rods resiliently biased to return to a pre-defined shape.

3. The device of claim 2, further comprising an elongated hollow

structure for storage and deployment of the device, said inflatable receptacle and

said flexible rods being retractable within said elongated hollow structure so as to

confine said flexible rods to an initial state corresponding to said closed insertion

state of said inflatable receptacle, said flexible rods returning to said pre-defined

shape as they advance out from said elongated hollow structure.

4. The device of claim 3, wherein said elongated hollow structure forms

a storage stage of a two-stage trocar, an insertion stage of said trocar being configured for insertion through the skin of a patient as part of a minimal invasive

surgical procedure.

5. The device of claim 4, wherein said insertion stage of said trocar

includes a curved hollow guide portion for insertion within the patient, said curved

hollow guide portion providing a turn angle of between about 15┬░ and about 30┬░.

6. The device of claim 3, further comprising a manually operable

mechanism for displacing said inflatable receptacle and said flexible rods along a

length of said trocar.

7. The device of claim 1, further comprising a retaining mechanism

associated with said inflatable receptacle and configured for deploying around a

superventricular portion of the heart so as to retain said inflatable receptacle in a

position enveloping the ventricular portion of the heart.

8. The device of claim 7, wherein said retaining mechanism includes at

least one drawstring mechanism.

9. The device of claim 8, wherein said at least one drawstring

mechanism is connected to said inflatable receptacle via a non- inflatable web.

10. The device of claim 7, wherein said retaining mechanism includes at

least one inflatable retaining element, said inflatable retaining element and said

inflatable receptacle being provided with independent fluid supply conduits.

11. The device of claim 1, further comprising a retractable suction

clamping system including:

(a) a suction cup deployed for suction clamping to the apex of the heart;

and

(b) an axially displaceable tube forming a fluid connection with said

suction cup,

such that, when said tube is displaced forward and suction is applied to said tube,

said suction cup clamps to the heart and, when the suction is released and said tube

is displaced rearwards, said suction cup is withdrawn from contact with the heart.

12. The device of claim 1, further comprising at least one electrode

deployed on an inner surface of said inflatable receptacle so as to contact the heart

when the device is deployed.

13. A cardiac massage device deployable by a minimal invasive

procedure for applying pulsatory pressure to a ventricular wall of a heart, the

device comprising:

(a) an inflatable receptacle for substantially enveloping the ventricular

portion of the heart, said inflatable receptacle being configured to exert pulsating pressure against the ventricular wall in response to a

pulsating fluid supply; and

(b) a retaining mechanism associated with said inflatable receptacle and

configured for deploying around a superventricular portion of the

heart so as to retain said inflatable receptacle in a position

substantially enveloping the ventricular portion of the heart.

14. The device of claim 13, wherein said retaining mechanism includes

at least one drawstring mechanism.

15. The device of claim 14, wherein said at least one drawstring

mechanism is connected to said inflatable receptacle via a non-inflatable web.

16. The device of claim 13, wherein said retaining mechanism includes

at least one inflatable retaining element, said inflatable retaining element and said

inflatable receptacle being provided with independent fluid supply conduits.

17. A method of minimal invasive deployment of a cardiac massage

device around the ventricular portion of the heart of a patient, the method

comprising the steps of:

(a) introducing the device in a compact state through the pericardium in

the region near the diaphragm; and

(b) opening the device to form a receptacle which substantially

envelopes the ventricular portion of the heart.

18. The method of claim 17, wherein said opening of the device occurs

through a plurality of resiliently biased flexible rods deployed within the device

returning to a pre-defined shape.

19. The method of claim 17, further comprising application of suction

clamping to the surface of the heart during deployment of the device, and removal

of the suction clamping once the device is properly deployed.

20. The method of claim 17, further comprising deploying a retaining

mechanism around a superventricular portion of the heart so as to retain said

receptacle in a position enveloping the ventricular portion of the heart.

21. The method of claim 17, wherein said compact state exhibits a

maximum diameter of no more than about 4 cm.

22. The method of claim 17, wherein said compact state exhibits a

maximum diameter of between about 1.5 and about 2.5 cm.