Programmer For Segmented Balloon Pump

Abstract

A circuit for programming the inflation and deflation of a five segmented balloon pump as used in circulatory assist blood pump systems is disclosed. The rising and falling edges of wave pulses are used by a volume transducer to create a volume signal corresponding thereto. Means are provided to produce a plurality of signals corresponding to the rising edge of the waveform and a plurality of signals corresponding to the falling edge thereof. These signals are used to activate the various valves of the balloon pump and thereby inflate and deflate the segments.

Description

BACKGROUND OF THE INVENTION

The present invention relates to circuits for operating cardiac assisting balloon pumps and, more particularly, to a circuit for programming the inflation and deflation of a plural segmented balloon pump as used in circulatory assist blood systems.

As is well known, the systemic circulation is maintained by the action of the left ventricle in pumping blood into the aorta, or main artery. A back-flow of blood into the left ventricle is prevented by the aortic valve. During its contraction (systole) the left ventricle works primarily against the elastic compliance of the aorta, raising the pressure in the aorta and distending it. As soon as contraction is complete and the ventricle relaxes, the aortic valve closes and the elastic contraction of the aorta then maintains a continuing flow of blood through the capillaries and other vessels (diastole). In addition to its function as a vessel for carrying blood to various organs, the aorta thus acts as an elastic reservoir storing some of the energy supplied to the heart. In many cases of heart insufficiency, it is found that the aorta has become relatively stiff and inelastic because of physiological processes, and thus requires excessive pressures from the heart to maintain normal circulation.

Heretofore, mechanical assistance to the systemic circulation has been attempted by veno-arterial pumping, left-heart bypass, diastolic augmentation, intra-arterial balloon pumping, and counterpulsation.

Thus, situations are frequently encountered in the treatment of heart patients where the patient's heart action is simply not sufficient to supply the patient's bodily needs. Frequently, the situation is encountered that while the diastolic action of the heart will bring a volume of blood into the left ventricle of the heart sufficient to supply the bodily needs, this ventricle will not fully empty into the aorta. Or, should the ventricle fill the aorta with arterial blood, the systolic action of the heart is not thereafter sufficient in itself to completely discharge the blood content of the aorta into the arterial tree. Blood backs up, stagnates, and seriously impairs bodily function. Conventionally, weakness in heart action is termed heart failure.

From the foregoing, it will be understood that any practical auxiliary blood pump which will assist the natural heart action in some simple, reliable and predictable manner may be expected to receive recognition and acceptance within the medical field and, as well, to subserve a strongly practical function. That the problem is difficult, however, is apparent simply upon considering that, despite long-felt and very prominent need for such external assistance, and despite the substantial thought, study and work which have been devoted over the years to this overlying problem, no really entirely satisfactory solution has yet been evolved, either as a method of long term treatment or as a physical embodiment of heart-assisting means.

For one reason or another, therefore, the many proposals heretofore propounded by the medical researchers have fallen short of certain desirable requirements, thereby failing in complete acceptance within the healing arts. Either they have proved too difficult, delicate and/or uncertain to maintain reliable operation, or partially impractical in fulfilling requirements of either proper relationship with natural heart action or volumetric response to desirable standards. Other proposals and/or related equipment have failed to respond to minimum standards or adjustability to meet adequately the requirements of the cardiac specialist.

SUMMARY OF THE INVENTION

From the foregoing discussion it will be clear then that the present invention provides an improvement over prior devices and will fill a long needed requirement in the field of circulatory assist blood systems. Intra-arterial or "balloon" type pumps per se, for use, for example, in the aorta by insertion through the femoral artery, up the arterial tree and into the aorta, are well known. However, the operation of the pump is extremely critical since it must operate periodically in a transient or instantaneous pulsating manner which must be synchronized with the patient's heart. Furthermore, the stroke of such a pump must operate under various types of conditions such as at different pressures relating to the pressure of the patient. The present invention, then, fulfills these conditions by providing a circuit when accurately and reliably operates a balloon pump to meet these special requirements. A balloon pump disclosed in U.S. Pat. No. 3,504,662, is divided into separate fluid retaining compartments, and, under the programmed control of the present invention, these compartments are adapted to be pneumatically actuated at different rates to provide, for example, a controlled action and/or actuation of the middle compartment or compartments prior to or at a more rapid rate than the end compartments.

An object of the present invention is to provide for improved cardiac assistance.

Another object of the invention is the provision of a control system for the operation of balloon type blood pumps.

Another object of the invention is to provide a control system which will operate an intra-arterial ballon pump with a generally peristolic action.

Still another object of the invention is the provision of a control system for operating the segments of a balloon pump at different rates of inflation.

Yet another object of the invention is the provision of a control system for a balloon pump wherein expansion of both its ends portions prior to expansion of its center portion is prevented.

Other objects and many of the attendant advantages of the instant invention will be readily appreciated as the same becomes better understood by reference to the following detailed description of an embodiment when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof, it being understood that this embodiment is to be intended as merely exemplary and in no way limitative.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a typical balloon type pump having three inflatable segments;

FIG. 2 shows a block diagram of the control circuit making up the invention; and

FIG. 3 shows the waveforms produced at various points in the control circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring briefly to FIG. 1 there is shown a typical balloon pump, the inflating and deflating of which might be controlled or programmed by the present invention. Structure-wise these pumps have a plurality of segments which are individually inflated and deflated to augment a patient's blood flow. Intra-arterial balloon pumping techniques are based on the principle that the expansion of the balloon within the artery displaces the blood from the region between the balloon and the inner wall of the artery, the individual sections of the pump functioning in sequence to assist in moving the blood. Thus the pump may have a central gas release tube 10 extending from an elongated catheter and running the length of the device, and an outer flexible membrane 11, the membrane 11 being fastened to tube 10 at points such as 12 and 13 to form a plurality (in this illustration three, or it may be five) of fluid retaining compartments 14, 15 and 16.

Each compartment has an opening as 17, 18 and 19 into tube 10 for the release and admittance of inflating gas pumped into tube 10 through the catheter and the pressure receiving end 53, the openings 17, 18 and 19 being provided with electrically controlled valves 17a, 18 a and 19a to control the inflation and deflation of each particular compartment. The membrane 11 is attached at its ends 51 and 52 to form the ends of the balloon and the leading end is closed by a plug 52 which may house a transducer.

In the block diagram of FIG. 2 there is a volume transducer 20 which is utilized to respond to the patient's blood flow, the output of transducer 20 being applied to an emitter follower 21 and on to a capacitor-diode combination 22 and 23. A second emitter follower 24 is connected to capacitor 22 and the output of 24 is divided into two channels, one of these channels furnishing a signal to a comparator 25. It should be mentioned at this point that there are a plurality of comparators, the number matching the number of segments or compartments in the pump, and for the sake of simplicity in the drawings, only one is shown in FIG. 2.

The second output from emitter follower 24 is applied to a diode 26 and capacitance 27 before going to complimentary emitter followers 28. Connected between the output of complimentary emitter followers and ground there are a plurality of potentiometers R.sub.1 -R.sub.5, the number matching the number of comparators 25, the moving arm 30 of each potentiometer being connected to a comparator 25.

The signal from capacitance 22, besides being applied to emitter follower 24, is also applied to a volume signal inverter 31. After inversion the signal passes through a capacitance 32, with a diode 33, before going to an emitter follower 34. The output of follower 34 again divides, one signal path going to comparaton 35, while the other path goes through diode 36 to complimentary emitter follower 37, and on to a plurality of potentiometers R.sub.6 -R.sub.10. Sliding arm 38 of each potentiometer forms a second input to comparator 35.

There are a plurality of monostable multivibrators 40, one for each signal channel, the output of comparator 25 and diode 41 forming one input to the multivibrator 40, and the output of comparator 35 and diode 42 forming the other. Outputs from the multivibrators 40 are used to activate the pulse valve drivers 43, these in turn acting to flex the compartments 14, 15 and 16 of the balloon pump.

It should be obvious from the above description of the structure of the invention, when considered along with FIG. 2, that there are a plurality of signal channels involved, the number depending upon the number of segments in the balloon pump. Thus, if there are five segments, then there are five potentiometers in R.sub.1 -R.sub.5 and R.sub.6 -R.sub.10, also five comparators in 25 and 35, five monostable multivibrators 40, and five pulse valve drivers 43.

Also it should be noted from FIG. 2 that there is a positive signal channel and a negative signal channel, the positive channel terminating in comparator 25 while the negative channel terminates in comparator 35.

In operating the invention the device develops the waveforms shown in FIG. 3, with the identifying letter of each waveform corresponding to the same testpoint on FIG. 2. Thus, the volume signal as generated by volume transducer 20, in response to the patient's blood flow, is passed on to emitter follower 21 and then clamped to zero or ground by means of capacitance 22 and diode 23. This clamped signal is connected to another emitter follower 24 which produces two outputs. One of these outputs is connected to the base of a transistor operating as a comparator 25 while the other output feeds a diode 26. From diode 26 the signal is passed to capacitance 27, where through the charging action of the capacitance the peak signal is held for several seconds. Complimentary emitter followers 28 provide a proper buffer to connect the peak (DC voltage) to potentiometers R.sub.1 through R.sub.5. The center arm 30 of one of these potentiometers is connected to the emitter of comparator 25, and by adjusting the potentiometer the trigger produced at the output of comparator 25 (testpoint E) may be phased anywhere along the leading edge of the volume signal from transducer 20. There may be five such potentiometers and five comparators, thus five triggers are generated that may be phased in any position with respect to one another. Reference to waveforms A, B, C, D and E in FIG. 3 will provide a clearer understanding of the above operation.

The comparators used throughout the circuit will respond only to positive going signals on their respective bases. This being the case, the volume pulse from transducer 20, and feed off at point B, is inverted by signal inverter 31 and the signal producing circuitry is duplicated to match the previous channel. In accomplishing this, the signal from inverter 31 is clamped to ground by capacitance 32 and diode 33. From emitter follower the signal divides to comparator 35, and to diode 36 whence its peak is held by capacitance 39. Complimentary emitter followers 37 produce signals on potentiometers R.sub.6 through R.sub.10, and the center arm 38 on one of these potentiometers produces a second input to comparator 35. Thus, phasable triggers are produced anywhere along the rise and fall of volume meter movement and transducer signal 20. Reference to waveforms F, G, H, I and J will display the phase relationship of the second set of five triggers.

The ten triggers are connected in pairs to five monostable multivibrators 40 through diodes 42 and each multivibrator produces two pulses; one in phase with the rise of the transducer signal and the other in phase with its fall. The five multivibrator outputs are connected to pulse valve drivers 43 which may be used to control valves (not shown) for inflating and deflating the balloon segments 14, 15 and 16. See waveforms K and L of FIG. 3. Thus, the pulse in phase with the rise in signal inflates the balloon segment, while the pulse in phase with the fall deflates the segment. Since the segments operate in sequence, at different speeds, and synchronized with the patient's heart beat, circulation of blood through the aorta is boosted.

From the above description of the structure and operation of the invention it is obvious that there is disclosed a new and novel means for programming the operation of a balloon blood pump. Through selective phasing of the generated triggers, segments of the pump are inflated and deflated at varying speeds to provide a beneficial and healthful peristolic assistance to blood flowing through a patient's aorta.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

What is claimed is:

1. A circuit for programming a mult-segment ballon blood pump having a valve for each balloon segment, comprising

means for sensing the heart rhythm of a patient using the balloon pump, said sensing means including a volumetric transducer for producing a volume signal, the waveforms of which are synchronized with his blood flow;

a first signal channel means for transporting a plurality of first waveforms;

a second signal channel means for simultaneously transporting a plurality of second waveforms; said second waveforms being the inverse of said first waveforms;

a pair of comparators, said pair of comparators including a first comparator connected to said first signal channel means for producing a plurality of first trigger pulses phased with the rising edge of said first waveforms and a second comparator connected to said second signal channel means for producing a plurality of second trigger pulses phased with the falling edge of said second waveforms, there being a pair of comparators for each balloon segment; and

means connected to said pair of comparators for utilizing the first and second trigger pulses to active and deactivate the valves of the balloon pump, said utilizing means including a plurality of monostable multivibrators and a plurality of pulse valve drivers connected to said multivibrators, there being a multivibrator and a pulse valve driver for each pair of comparators.

2. The device of claim 1 wherein said first signal channel means includes:

a first emitter follower;

a second emitter follower connected to said first emitter follower and said first comparator;

clamping means connected to said first emitter follower for grounding said volume signal;

a complimentary emitter follower connected to said second emitter follower and said first comparator, wherein part of the output of said second emitter follower goes to said first comparator and part of said output goes to said complimentary emitter follower;

means connected between said second emitter follower and said complimentary emitter follower for detecting and holding the peak of said part of said output of said second emitter follower which goes to said complimentary emitter follower; and

a potentiometer connected between the output of said complimentary emitter follower and ground, the moving arm of said potentiometer being connected to said first comparator for variably phasing said first trigger pulses.

3. The device of claim 2 wherein there is a complimentary emitter follower, potentiometer and comparator in the first signal channel for each segment in the balloon pump.

4. The device of claim 1 wherein the second signal channel means includes:

a signal inverter for inverting said volume signal;

a first emitter follower connected to said signal inverter;

clamping means connected to said first emitter follower for grounding said inverted volume signal;

a complimentary emitter follower connected to said first emitter follower and said second comparator, wherein part of the output of said first emitter follower goes to said second comparator and part of said output goes to said complimentary emitter follower;

means connected between said first emitter follower and said complimentary emitter follower for detecting and holding the peak of said part of said output of said second emitter follower which goes to said complimentary emitter follower; and

a potentiometer connected between the output of said complimentary emitter follower and ground, the moving arm of said potentiometer being connected to said second comparator for variably phasing said second trigger pulses.

5. The device of claim 4 wherein there is a complimentary emitter follower, potentiometer and comparator in the second signal channel for each segment in the balloon pump.