Portable Mechanical Ventricular Assistance Device

Abstract

A portable mechanical ventricular assistance device including a ventricular assistor cup designed to receive the ventricles of the heart. The cup assembly is comprised of a rigid shell having a configuration generally conforming to the surface configuration of the heart ventricles and a flexible liner which is caused to contract and expand about the heart ventricles to effect the pumping action. The heart ventricles are retained within the cup by a substantially sustained negative pressure while the pumping action is produced by the application of alternating positive and negative pressure pulses to the cup. Both the sustained negative pressure and the positive and negative pressure pulses are generated by a hand pump assembly which includes a manually operable handle connected through a piston rod to a reciprocating piston mounted within the cylinder of the pump. The piston effectively divides the cylinder into two chambers, one of which is coupled through a conduit to provide the sustained negative pressure to the cup. The remaining chamber is coupled through a second conduit to the ventricle assistor cup to provide for the alternating positive and negative pressure pulses. Suitable adjustable relief valves are provided in each of the conduits to regulate the pressure levels and the positive or negative pressure directed to the cup.

Description

The present invention relates to circulatory sustaining devices, and more particularly to a novel portable mechanical ventricular assistance device for sustaining the pumping action of a heart.

Numerous devices have been developed to either sustain the circulatory function of a patient, or, alternatively, to sustain the pumping action of a heart. All such devices may be classified into two basic categories; namely, bypass systems and indirect pumping systems. Devices falling into the category of bypass systems are designed to bypass the flow of blood from the heart and to maintain the pumping action otherwise performed by the heart through mechanical or electromechanical devices. Devices falling into the indirect pumping category are designed to assist the heart in the performance of its pumping function. The present invention falls into the latter category.

Devices classified in the former category are usually quite complex in nature and rather large in size so as to limit their use to operating rooms and effectively prohibit their use as a portable device.

Devices developed up to the present which are classified in the latter category are normally comprised of motor means for developing the necessary pressure or vacuum levels and are further comprised of electromechanical means for regulating the flow of the necessary pressure levels to the heart pump. Such equipment is likewise heavy in nature and large in size so as to prohibit its use as a truly portable device.

Devices of the indirect type have been used with great success in the fields of heart and organ transplants. When a potential cadaver (donor), whose organ or organs are available for transplant purposes, is to receive mechanical ventricular assitance, the assistor system is rushed to him for the purpose of sustaining the heart pumping action. Under present-day techniques and with present-day device, in order to transport the cadaver to the operating room, the assistor is temporarily disconnected, due to the fact that it is too bulky and requires too much electrical power to perform the circulatory function during the time in which the donor is being moved. The period during which the assistor device is disconnected may thus have a harmful effect upon the organ or organs to be transplanted.

The device of the present invention, which is designed to be truly portable and to be simple to connect and operate, is extremely advantageous for use during the period of time in which the donor is being moved from one location to another, as well as for other emergency situations.

The present invention is comprised of a ventricular assistor cup assembly having a rigid outer shell of a configuration substantially conforming to the surface configuration of the heart ventricles. The cup contains a flexible liner capable of expanding and contracting about the heart ventricles to perform assistive pumping action.

The cup is provided with a first large opening for receiving the heart ventricles. A second opening provided at the apex of the cup receives the sustained negative pressure necessary to retain the ventricles within the cup assembly. A third opening provided in the cup along the surface thereof and intermediate the first and second openings is designed to receive the pulsatile pressures of alternating positive and negative pressure pulses which cause the contraction and expansion of the flexible liner about the heart ventricles.

All of the above-mentioned pressures are provided through the use of a single portable pump assembly having a first handle adapted to receive and position the operator's foot for holding the pump steady during operation. A second manually operable handle is provided for driving a reciprocating piston mounted within the pump cylinder. The piston effectively divides the pump cylinder into first and second chambers, each of which is coupled through an associated conduit to the sustained negative pressure opening and the pulsatile pressure opening, respectively. Adjustable relief valves are provided in the pulsatile pressure conduit to control the pressure (or vacuum) level of the pulse injected into the pulsatile pressure conduit. Similar adjustable relief vales are provided in the sustained negative pressure conduit for controlling the level of negative pressure and for bypassing positive pressure pulses from reaching the assistor cup assembly. An additional one-way valve assembly is provided in the sustained negative pressure conduit to prevent positive pressure pulses from reaching the assistor cup assembly and to maintain the negative pressure developed in the cup during the application of positive pressure pulses to the sustained negative pressure line.

The simplicity and portability of the system make it extremely advantageous for use in a variety of applications, especially those of an emergency nature. The portable system described herein may be easily and rapidly substituted for conventional assemblies in moving donors from one location to another, or may be used in emergency situations to sustain the circulatory function until such time as the patient is moved to a hospital.

It is, therefore, one object of the present invention to provide a nevel portable mechanical ventricular assistance device.

Still another object of the present invention is to provide a novel pump assembly for use with ventricular assistor cup assemblies, and the like, which is capable of developing a sustained pressure at a first output thereof and which is capable of developing a pulsatile pressure of alternating positive and negative pressure pulses at the second output thereof.

Yet a further object of the present invention is to provide a novel pump assembly for use with ventricular assistor cup assemblies, and the like, which is capable of developing a sustained pressure at a first output thereof and which is capable of developing a pulsatile pressure of alternating positive and negative pressure pulses at the second output thereof, whereby the pressure levels of the sustained and alternating pressure pulses are made adjustable through the use of adjustable valve means associated with each of the hand pump outputs.

These as well as other objects of the present invention will become apparent when reading the accompanying description and drawings in which:

FIG. 1 shows a diagrammatic view partially sectionalized of the pump assembly of the present invention as applied to a ventricular assistor cup assembly.

FIGS. 2a and 2b are schematic diagrams showing alternative embodiments for the pump portions of the assembly.

The device of the present invention is comprised of a hand pump assembly 10 for use in operating a ventricular assistor cup assembly 20.

The ventricular assistor cup assembly is described in greater detail in copending application (M-6019) Ser. No. 785,652, filed Dec. 20, 1968 and assigned to the assignee of the present invention, which description is incorporated herein by reference thereto. For this reason, a detailed description of the assistor cup assembly will be omitted from this application for purposes of simplicity. For purposes of understanding the present invention it is sufficient to understand that the assistor cup assembly 20 is comprised of a rigid cup 21 having a first large opening 22 for receiving the ventricles of the heart; a second opening 23 arranged at the apex of the cup for receiving a sustained negative pressure line; and a third opening 24 for receiving a pulsatile pressure line. The interior of the cup is provided with a flexible liner 25 secured at 26 and 27 by suitable adhesive means, for example, near the apex opening 23 and the large opening 22, respectively. The liner 25 is mounted within and sealed to cup 21 in such a manner as to form a hollow interior space whose only opening is opening 24 which receives the pulsatile pressure line. The injection of positive pressure into this hollow interior space causes the contraction of liner 25 which, in turn, contracts the ventricles of the heart embraced by the liner. Injection of a negative pressure pulse returns the liner 25 substantially to the position shown in FIG. 1 to allow for expansion of the heart ventricles. This operation is continuously repeated to assist the heart in sustaining its pumping function. The apex opening 23 receives the substantially sustained negative pressure to retain the ventricles within the cup throughout the entire pumping operation and independently of the pulsatile pressure applied to opening 24.

The portable pump assembly 10 for use with the ventricular assistor cup assembly 20 is comprised of a cylinder 13 having secured at one exterior end thereof a handle 12. The cylinder contains a reciprocating piston 14 of the double-acting piston type. Piston 14 is coupled through a piston rod 15 to an exterior mounted handle 11. The opening provided for piston rod 15 at the upper end of cylinder 13 may be provided with a suitable seal such as an O-ring 16 to prevent the escape of compressed air from the cylinder.

Piston 14 effectively divides the cylinder into first and second piston chambers 17 and 18.

Upper chamber 17 is provided with an opening 18 for receiving a sustained negative pressure conduit 31 which couples chamber 17 through a liquid trap 32 and conduit 33 to the opening 23 provided in the apex of assistor cup 21.

Lower chamber 18 is provided with an opening 34 for receiving a conduit 35 coupling the chamber to the pulsatile pressure opening 24 in cup 21.

Suitable valve means are provided in the conduits connecting the assistor cup to the pump assembly for regulating the pressure level and pressure direction of pressure pulses injected into each of the lines. The conduit 31 is provided with a first one-way valve assembly 36 which may, for example, be comprised of first and second spaced annular rings 37 and 38 arranged in the interior of conduit 31. A spherical member or ball 39 is normally urged against annular-shaped ring 38 by a bias spring 40 secured at one end to annular disc 37 and having its opposite end bearing against ball 39.

Similar one-way valve assemblies 41 and 46 are arranged at spaced intervals along conduit 31 to perform functions which will be more fully described.

In a like manner, positive and negative relief valve assemblies 53 and 58 are arranged at spaced intervals along the surface of conduit 35 for functions to be more fully described.

The upper piston chamber 17 provides the sustained negative pressure for the ventricular assistor cup which is obtained on the "down" stroke of piston 14. Let it be assumed that the piston 14 is positioned near the top of cylinder 13 and is moved vertically downward in the direction shown by arrow A. A negative pressure or vacuum is developed in chamber 17. Due to the pressure differential across the right-hand and left-hand sides of one-way valve 36, ball 39 is caused to unseal the opening in ring 38, allowing this negative pressure (i.e., vacuum) state to communicate with the apex opening 23 in cup 21.

The relief valve assembly 46 is adjusted to cause ball 49 to unseal the opening in ring 50 when the negative pressure in conduit 31 is greater than a predetermined threshold level. The relief valve 46 thus automatically controls the maximum negative pressure applied to the assistor cup. The maximum negative pressure may be made adjustable by providing suitable means for adjusting the bias applied to ball 49 by bias spring 48. A suitable filter member 51 is secured between ring 50 and ring 52 to filter out dust or any other unwanted particles carried by the air entering into the system when valve 46 opens.

The negative pressure applied to the assistor cup is sustained until the piston 14 reaches the bottom of its stroke. On the "up" stroke, i.e., when the piston moves from the bottom of its stroke upward in the direction shown by arrow B, one-way valve 36 is sealed to prevent positive pressure from passing the valve and communicating with the assistor cup. The sealing of valve 36 during the entire "up" stroke also acts to maintain the negative pressure in assistor cup 20 until the next "down" stroke. One-way valve 41 releases the pressure being developed in upper chamber 17 during the upward stroke by having its ball 42 moved downwardly against the force of bias spring 43 to unseal the opening in annular-shaped ring 44. The negative pressure developed in conduit 31 during a "down" stroke of piston 14 is thus sustained during the"up" stroke of piston 14. The liquid trap 32 traps any liquid passing from cup assembly 20 toward the sustained negative conduit 31.

Lower piston chamber 18 operates in much the same manner as upper chamber 17 except that both positive and negative pulsatile pressures are applied to cup opening 24 by line 35. For this reason, conduit 35 is provided with two relief valves, one for positive pressure 53 and one for negative pressure 58.

During an "up" stroke of piston 14, i.e., when piston 14 moves in the direction of arrow B, a negative pressure or vacuum is developed in conduit 35 and is coupled to cup opening 24, causing the flexible liner 25 to move from a contracted position to the relaxed position shown in dotted line fashion in FIG. 1. If this negative pressure exceeds a predetermined threshold level, the ball 59 of relief valve 58 will move downward against the force of biasing spring 60 to unseal the opening in ring 61, thereby automatically controlling the maximum negative pressure which may be developed in conduit 35.

During a "down" stroke of position 14, i.e., when the piston moves from its uppermost position downward in the direction shown by arrow A, a positive pressure is developed in lower piston chamber 18, causing a positive pressure pulse to be injected into opening 24 of the ventricular cup assembly. This causes the flexible liner 25 to contract the ventricles of the heart encircled by the liner. If the positive pressure injected into conduit 35 exceeds a predetermined threshold level, ball 54 of relief valve 53 will be caused to move upwardly against the force of bias spring 55 to relieve the excess positive pressure developed in conduit 35. The relief valves 53 and 58 thereby automatically control the positive and negative pressure pulses delivered to the ventricular cup assembly 20. Suitable adjustable means may be provided in both the positive and negative relief valve assemblies 53 and 58, respectively, to adjust the force of the biasing springs an thereby calibrate the maximum positive and negative pressure levels. The relief valves further limit the pressures as necessary for full strokes, regardless of the ventricular cup-pumping displacement. The negative relief valve assembly is provided with a filter 63 to filter out any unwanted particles or other material which may be in the atmosphere against entering into the system with the air entering through the relief valve assembly 58 whenever it is caused to open.

The pump may be operated by one person in a variety of ways. One preferred manner of operating the pump is to place one foot through the opening formed by stationary handle 12 and operating the movable handle 11 in a reciprocating fashion by grasping and moving handle 11 with either one or both hands. Alternatively, each of the handles 11 and 12 may be grasped by one hand, and the pump may be operated in a reciprocating fashion in this manner. Obviously, if desired, two persons may operate the pump, but the simplicity of operation and size of the pump does not necessitate such alternative operation.

FIGS. 2a and 2b show alternative arrangements for the pump assembly of FIG. 1. Considering FIG. 2a, the pump arrangement 10' is a bellows pump selectively expandable and contractable due to its bellows arrangement 70. The interior of the bellows arrangement is divided by a barrier wall 71 forming upper and lower chambers are coupled to conduits 31 and 35 of FIG. 1 in the same manner as the pump assembly shown in FIG. 1. Operation of the pump assembly of FIG. 2a may be performed in the same manner as the device shown in FIG. 1 by grasping the handles 11 and 12 and urging them alternatively together and apart to create the positive and negative pressure phases occurring during each reciprocating cycle.

FIG.2b shows an alternative pump assembly 10" having a bellows assembly 70 comprised of a single internal chamber 72 having openings 73 and 74 for communicating with the conduits 31 and 35 of FIG. 1. In operation, the handles 11 and 12 are alternately urged toward one another and apart from one another to create positive and negative pressures within the internal chamber 72 to provide the positive and negative pressure signals in conduit 35 while providing only a sustained negative pressure signal in conduit 31.

When using the double-acting piston type of FIG. 1, it is possible to develop sustained negative pressure in conduit 31 during both the "up" and "down" stroke by coupling an additional conduit near the bottom of cylinder 13 which is provided with valve assemblies substantially identical to the assemblies 36, 41 and 46. This additional conduit may be coupled into conduit 31 as shown by dotted line 31'. Thus, each stroke, whether "up" or "down", of the piston will contribute to sustaining the negative pressure in the assistor cup assembly. This alternative embodiment may be used in cases where the pump assembly is capable of providing a sufficient negative pressure pulse for operating the flexible liner 25 and for simultaneously sustaining the negative pressure maintained at the opening 23 of the assistor cup assembly.

It can be seen from the foregoing description that the present invention provides a novel portable pump assembly especially advantageous for use with ventricular assistor cup assemblies to maintain and sustain the pumping operation of the heart by providing an independent sustained negative pressure (vacuum) at one output thereof and by providing alternating positive and negative pressure pulses at a second output thereof for performing the functions necessary in the operation of such a ventricular cup assembly. It should be obvious that various modifications may be made in the pump assembly without departing from the scope of the invention. For example, a one-way valve of the type shown in conduit 31 may be provided in conduit 35 for providing sustained negative pressures in each of the outputs developed by the pump for such applications in which negative pressures of this type might be required. The negative pressure values obtained may be adjusted to be of different values through simple adjustment of the valves. As a further modification, the one-way valves provided within each of the conduits 31 and 35 may be reversed in direction of operation so as to provide a first output for generating a positive sustained pressure and a second output for generating a sustained negative pressure. As still another alternative, the one-way valve assembly 36 provided in conduit 31 may be omitted to provide a pump having two outputs, each of which is capable of providing alternating positive and negative pressures wherein each of the positive and negative pressures developed by each of the outputs may be set at any predetermined threshold levels, depending upon the needs of the user. In addition, the single cylinder having a double-acting piston may be replaced by two cylinders each having a reciprocating piston. The cylinders may be placed side-by-side and arranged to be reciprocated by a single operating handle.

The assemblies of the figures may be operated by mechanical or electromechanical means, if desired. For example, a motor M may drive a reciprocating arm A through shaft S which is coupled to handle 11 of FIG. 1. A rotary to reciprocating motion device D converts the rotation of the shaft S into reciprocating movement. Alternatively, a relay R having a reciprocating armature RA may be alternately energized and deenergized to reciprocate up and down (for example) to impart reciprocating movement to the piston rod 15 (for example). The down stroke may be imparted by energizing the relay driving its armature downward. Deenergization of relay R will cause the upstroke under control of a biassing spring (not shown).

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and, therefore, the scope of this invention is limited not by the specific disclosure herein, but only by the appended claims.

Claims

I claim:

1. A portable mechanical ventricular assistance device comprising:

a ventricular assistor cup assembly including a rigid cup having an interior configuration adapted to receive the ventricles of the heart;

a flexible liner mounted within said cup having a first opening for receiving the ventricles of the heart; a first port positioned at the apex of the cup opposite the first opening, and a second port positioned intermediate the first opening and the first port;

said flexible liner being sealed to the interior surface of said cup along a first marginal portion adjacent to and surrounding said first opening and along a second marginal portion adjacent to and surrounding said first opening and along a second marginal portion adjacent to and surrounding said first ports;

A first-sustained negative pressure conduit having a first end coupled to said first port;

a second pulsed positive and negative pressure line having a first end coupled to said second port;

reciprocating pump means having first and second outputs each capable of developing positive and negative pressure pulses during reciprocation of said pump;

said first and second outputs being respectively coupled to the second ends of said first and second conduits;

valve means coupled in said first conduit for coupling only negative pressure pulses to said first port.

2. The device of claim 1 further comprising first and second relief valve means connected to said second conduit for limiting the maximum positive and negative pressure pulses delivered to said second port.

3. The device of claim 1 further comprising first relief valve means coupled to said first conduit for limiting the negative pressure pulses delivered to said first port to a predetermined threshold level; and second one-way valve means for releasing positive pressure pulses injected into said first conduit to the atmosphere.

4. The device of claim 1 further comprising a liquid trap coupled between said first conduit and said first port for preventing the flow of any liquid toward said pump means.

5. The device of claim 1 wherein said pump means is comprised of a cylinder containing a reciprocally mounted double-acting piston dividing said cylinder into first and second chambers;

said first and second outputs communicating respectively with said first and second chambers.

6. The device of claim 1 wherein said pump means is comprised of a cylinder having a collapsible bellows-type wall;

said first and second outputs communicating with the interior of said cylinder.

7. The device of claim 1 wherein said pump means is comprised of a cylinder having a collapsible bellows-type wall;

a barrier wall in said cylinder dividing said cylinder into first and second chambers;

said first and second outputs respectively communicating with the interiors of said first and second chambers.