US3410263A - Blood-pumping apparatus provided with heart synchronizing means - Google Patents

Description

Nov. 12, 1968 G. E. MCGINNIS 3,410,263

BLOOD-PUMPING APPARATUS PROVIDED WITH HEART SYNCHRONIZING MEANS Filed May 13, 1965 2 Sheets-Sheet 1 FIGI.

Nov. 12, 1968 G. E. MCGINNIS 3,410,263

BLOOD-PUMPING APPARATUS PROVIDED WITH HEART SYNCHRONIZING MEANS 2 Sheets-Sheet 2 Filed May 13, 1965 DIASTOLE SYSTOLE mmswwwmm QOOJm F IGJI DIASTOLE DIASTOLE SYSTOLE TIME FIGJII United States Patent Office 3,410,263 Patented Nov. 12, 1968 3,410,263 BLOOD-PUMPING APPARATUS PROVIDED WITH HEART SYNCHRONIZING MEANS Gerald E. McGinnis, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 13, 1965, Ser. No. 455,377 Claims. (Cl. 1281) ABSTRACT OF THE DISCLOSURE A unitary blood-pumping apparatus having a resilient diaphragm means which is alternately pneumatically-distended and self-returned to pulsedly supply and withdraw blood to and from the arterial system of a patient for diastolic pressure augmentation. A pneumatic storage volume in the unit, charged from a source of compressed gas for operating the diaphragm means during each period of return movement thereof, provides for rapid initiation of diaphragm distention during the blood pumping periods. A solenoid valve in the unit, synchronized with the patients heart beat, controls the periodic supply from the storage volume to the diaphragm means and release from the latter.

Medical experimentation is being conducted in the use of diastolic pressure augmentation for treating victims of coronary thrombosis, which is a medical term for an obstruction of one of the coronary arteries feeding the heart muscle. The theory underlying diastolic pressure augmentation can be explained by considering the heart at a specific instance in its cycle of operation.

During each heart beat or cycle, the heart muscles first contract to force blood to the main artery, the aorta, by way of the aortic valve, a check valve, thence to the arteries which communicate with the aorta, including the coronary arteries which feed blood to the heart itself. The resulting pressure rise in the arteries, with the exception of the coronary arteries, causes these elastic vessels to stretch and store some of the energy of the systolic action of the heart. The contraction of the heart during systole, however, distorts the coronary arteries and tends to prevent blood flow thereto at this time. During subsequent relaxation of the heart muscles, diastole, the expanded or stretched arteries of the body will cause blood to fiow momentarily in a reverse direction in the heart to cause closure of the aortic valve and to supply blood to the coronary arteries. Thus, during the time that pressure created by the heart is the highest at the coronary artery inlets, there is restricted blood flow because of the distortion experienced by the coronary arteries during contraction of the heart. It will be seen then that the rate of blood flow to the coronary arteries is normally cyclical and out of phase with the heart discharge pressure in the aorta.

Coronary thrombosis is a condition in which a blood clot obstructs one of the coronary arteries feeding the heart muscle. During existence of such obstruction of one of the coronary arteries, circulation of blood to the affected area is established by collateral circulation by way of existent alternate arterial paths which tend to become enlarged for permanent bypass of the obstructed artery or until such time that the artery should become unobstructed. During the period of collateral circulation, the affected muscle area of the heart tends to be taxed and deficient in blood supply. In accord with present theory, it is believed that both the work load of the affected heart muscles can be reduced and circulation of blood through the alternate arterial paths can be enhanced by augmentation of the blood pressure during heart diastole, which is the period at which the expanded arteries of the body cause flow of blood to the coronary arteries, as aforedescribed.

The above reasoning has led to experimental diastolic pressure augmentation systems aimed at functioning to reduce the work load imposed on the heart during systole by withdrawal of blood from the arteries to an external augmentation pump, which in effect reduces the back pressure against which the heart must pump, and to return blood to the arteries at an increased pressure during diastole by such external pump, to increase the blood flow to the coronary arteries.

Such a diastolic pressure augmentation system must be susceptible of synchronizing the external pumping action with the natural pulse rate of the heart, which may vary from 50 to beats per minute; it must be susceptible to pumping the blood Without undue damage to the red corpuscles, which can result from turbulent and violent pumping action imposed on the blood; and it must be capable of effecting the withdrawal of blood from the arteries during the hearts systolic periods without causing arterial flutter, which is successive periods of complete collapse of the arteries due to successive periods of excessive suction conditions which might be imposed by the pump on the arteries during operation of such a system. Apparatuses heretofore proposed have been excessively complex and/or deficient in one or more of the foregoing requirements and accordingly it is a prime object of the present invention to provide a diastolic pressure augmentation system which is satisfactory in all such regards.

Other objects, features, and advantages of the inven tion will become apparent from the following detailed description thereof, when taken in connection with the accompanying drawings, in which:

FIGURE I is a side elevational view substantially in cross section showing an illustrative embodiment of the blood pumping apparatus of the present invention;

FIG. II is a time-pressure diagram showing typical blood pressure curves, with and without diastolic pressure augmentation; and

FIG. III shows schematically illustrative apparatus for effecting operation of the blood pumping apparatus of FIG. I in synchronism with a patients heart beat.

Referring to FIG. I, the blood pumping apparatus 1 is a unitary construction comprising a common housing 2, a local storage chamber 3' for storing a volume of compressed gas for operation of the blood pumping section 4, solenoid valve means 5 for controlling pulsating operation of the blood pumping section 4; and an actuating liquid section 6 interposed between the solenoid valve means 5 and the blood pumping section 4 to act as the intermediary through which the blood pumping section 4 is operated pneumatically.

The blood pumping section 4 comprises a flexible diaphragm 10 of resilient material interposed between respective cavities 11 and 12 in the two casing members 14 and 15. Chamber 12 acts as a blood pumping chamber on one side of the diaphragm 10 and chamber 11 acts as a liquid operating chamber on the other side. The portion of the casing section defining a fixed wall 16 of the blood pumping chamber 12 is substantially conical in shape, and the diaphragm 10 is mounted over the larger end of such conical-shaped'cavity defined by such surface.

The diaphragm 10 is made of a material which is flexible and stretchable so that when subjected to a preponderant pressure in the liquid chamber 11 it will distend in the direction of the blood chamber 12 to a position such as indicated by the dash lines 17 to cause displacement of blood from the conical chamber 12 to a central port 18 connected by such as flexible tubing, not shown, to

the aorta of a patient by way of such as the femoral artery to which the opposite end of such flexible tubing is connected by an inserted cannula. Such deflected displacement of the diaphragm is causing displacement of blood from the conical chamber 12, by virtue of the conical or tapered shape of the wall 16, tends to occur smoothly with a minimal turbulence and consequent minimal damage to the blood; minimal hemolysis. Any sharp corners which would have a tendency to create turbulence in egress of blood from the chamber 12 into the port 18 are absent in the configuration. At the same time, such conical shape of the wall 16 tends to lend support for the diaphragm as it is distended in the direction of the conical chamber 12. This tends to reduce stresses imparted to such diaphragm and thus tends to assure its reliable operation.

In the illustrative embodiment shown in FIG. I, the casing portion which defines the blood chamber 12 comprises an annular shoulder formed therein in encirclement of the larger end of the chamber 12 onto which an outer peripheral portion of the diaphragm 14) is clamped by means of an elongated retaining ring 21. During assembly of the pump, with casing parts 14 and 15 separated, the circular diaphragm 10 is placed over the open end of the conical cavity 12 in a concentric arrangement, and the solid ring 20- is advanced toward the casing portion to cause the outer periphery of the diaphragm to be clamped onto the annular shoulder 20, as well as against a radial shoulder 24 merging therewith by way of a gently rounded surface. The blood pump casing section 15, with diaphragm 10 thus clamped thereon, is then inserted into a cylindrical counterbore recess 25 in the other casing member 14 to bring the diaphragm 10 into exposure to the actuating-liquid chamber 11. Sealing between the two casing members is effected by an O- ring 28 disposed in a suitable groove in the casing member 15 and in sealing contact with the inner wall 25 of the counterbore. The actuating-liquid chamber 11 in the casing member 14 is formed by a cylindrical surface 39 which is about the same diameter as the effective diameter of the diaphragm 10. The casing portions are made of a transparent plastic material, such as sold under the tradename Plexiglas, to facilitate initial priming of the pump chamber 12 with blood and the chamber 11 with liquid. Blood or other blood-compatible liquid initially will be permitted to flow into the conical chamber 12 by way of the inlet-outlet port 18 while filling of such chamber is observed through the transparent casing, and such flow may be permitted to continue until rising above the level of the chamber into a bleed port at the top of such casing 15 which opens into the top of the conical chamber. After such initial priming of the conical chamber 12, the bleed port 35 will be closed by a suitable valve 36 Although the blood pumping diaphragm 10 is actuated pneumatically in accord with desirable features of the present invention, it may be so done preferably through the medium of a liquid which is compatible with the patients blood, such as a physiological saline solution, as a safety measure in the event that the diaphragm should rupture. Under such circumstances the liquid being pulsed to actuate the diaphragm 10 would then merely intermingle with the blood in the conical chamber 12 without any adverse effects on the patient.

As hereinafter it will be described in detail, the liquid in the chamber 11 on the backside of the diaphragm 10 of the blood pump section 4 is caused to flow to and from such chamber to cause the diaphragm 10 to oscillate back and forth for pulsing blood flow to and from the conical chamber 12 and hence to and from the patients aorta. Such pulsed operation is synchronized with the diastolic periods of the patients heart beat, by suit-able control of such pulsed flow of liquid to and from such chamber, as will be described hereinafter. During such actuation of deflection of the diaphragm 10 by displacement of liquid in the cylindrical chamber 11, the diaphragm deflection will cause a quantity of blood, such as 20 cc., for example, to be displaced from the conical chamber 12 into the inlet-outlet port 18 and the flexible tubing (not shown) into the femoral artery of the patient which results in a transient, acute, elevation of arterial pressure for such as diastolic pressure augmentation as discussed hereinbefore. Upon reduction in pressure of liquid in the cylindrical chamber 11, the arterial blood pressure will cause a return of blood to the conical chamber 12, as during each systole period of the patients heart beat, to cause return of the aforesaid amount of blood to the conical chamber. By such alternate displacement and return of the diaphragm 10, in synchronism with the heart beat, the patients arterial pressure will be augmented during each diastolic period. The stretch properties of the diaphragm, however, are such that an excessive suction is not created on the blood in the conical chamber during the return of the diaphragm toward a neutral position, and such return flow, or priming flow, will be limited primarily to the arterial pressure of the patient, so that excessive suction is not imposed by the pump on the arteries of the patient which would tend to cause the patients arteries to be subjected to fluttering, as aforedescribed herein. In this regard, an experimental pump has been tried which uses a diaphragm of natural gum rubber about of .an inch thick with an effective diameter of about 3 inches; the enlarged end of the conical recess being about 3 inches in diameter.

To effect pulsating displacement of the liquid in the cylindrical chamber 11, the actuating-liquid section 6 comprises a diaphragm 38, similar to diaphragm 10 which is subject opposingly to the liquid, in the cylindrical chamber 11 on one side and to pressure in a pneumatic-actuating chamber 40 on its opposite side. This second diaphragm 38 is mounted similarly to the diaphragm 10 of the blood pumping section 4 and is backed up on its pneumatic side by a perforated disc 41. By alternate pressurization and depressurization of the pneumatic chamber 40 the second diaphragm 38 will be deflected in the direction of the cylindrical chamber 11 to cause displacement of the liquid therein and corresponding displacement of the blood pumping diaphragm 10. If for any reason the blood pumping diaphragm 10 should become perforated, the system will continue to function by operation of the pulsing deflection of the second diaphragm 38 and any intermingling between the saline solution in the cylindrical chamber 11 with that of the blood in the conical chamber 12 will be without adverse effect on the patient and the pump can be continued in operation. Presuming, however that the operation of the blood pumping diaphragm 12 can safely be relied upon, the intermediate actuatingliquid section with its second diaphragm 38 can be dispensed with and the blood pumping diaphragm 10 [actuated directly by the pneumatic pressure pulses.

In accord with distinguishing features of the apparatus of the present invention, pneumatic actuation of the blood pump section 4 is highly desirable, inasmuch as it affords opportunity for operation by such as a pressurized air or oxygen supply in a hospital room, or bottled gas, without need for provision of separate complicated pressure supply systems such as is necessary where the pump is operated hydraulically. In behalf of affording such operability of the blood pump by pneumatic pressure, the apparatus of the present invention includes the pneumatic control valve means 5 in the form of a solenoid valve and the fluid pressure storage chamber 3 disposed substantially immediately adjacent to the blood pumping section 4. The storage chamber 3 affords immediate availability of a suitable quantity of compressed operating air or gas under control of the'adjacent solenoid valve. By virtue of this arrangement, time lags which otherwise might prevail were the pneumatic source remote from the blood pump, are eflectively eliminated and the blood pump can be operated pulsedly in synchronism with the patients heart beat. Thus, compressibility problems heretofore considered to prohibit use of pneumatic operation of such a pump are eliminated together with the inconvenience of provision of hydraulic-pressure-producing means. In an experimental model of applioants apparatus, the local storage chamber has been designed to have a volume of 500 ccs. in constant communication with an oxygen or air supply line in a hospital of 70 p.s.i., by way of a pressure regulating valve device 44, as indicated in FIG. III. The solenoid valve 5 is a three-way valve, as indicated schematically in FIG. III, which alternately establishes communication between the pneumatic chamber at one side of the second diaphragm 38 and a pneumatic outlet from the storage volume chamber and an exhaust port 46. By suitable timing of the intermittent energization and deenergization of the solenoid valve, as in synchronism with the patients heart beat, as well as by adjustment of storage volume pressure, relatively short high pressure augmentation as shown in curve B of FIG. II, or longer less intense pressure augmentation as shown in curve C of FIG. II, for example, can be effected.

In view of the desirability of placing the local storage chamber 3 and pneumatic control valve means 5 as close to the heart pump as possible, as well as the result of the realization of the desirability of so doing, the preferred construction of the present invention results in a unitary arrangement wherein the local storage chamber 3, the solenoid valve means 5, the actuating liquid section 6, and the blood pumping section 4 are arranged in series within a common enclosure in the form of the cylindrical housing 2 and an end wall construction, and retained therein by means of a plurality of elongated tie bolts (only one of which is shown) secured by wing nuts 51 to impart a clamping action between an end member 52 and an annular ring 53 encircling an annular face portion of the outer casing member 15 of the blood pumping section 4. Such unitary arrangement affords, in addition to a degree of compactness of the apparatus, also an assurance that the components will be disposed in close proximity to one another.

Referring to FIG. III, apparatus for controlling operation of the solenoid valve means 5 in synchronization with a patients heart beat, for sake of illustration, may simply comprise a source of electrical potential 55 for operating the solenoid of such solenoid valve means 5, a pair of pressure switch devices 56 and 57 for effecting energization and deenergization of the solenoid in accord with blood pressure information, a timing means 58 to adjust the time of response of the solenoid valve means according to a desired point of operation of the augmentation pumping mechanism relative to each heart beat cycle, a timing means 59 for adjusting the response of the augmentation-termination control switch 57 to determine the duration of blood pressure augmentation, and a means for coupling the pump control apparatus to a patient to sense the blood pressure information.

For illustrative purposes the augmentation-effecting pressure switch 56 may simply be one which includes a normally-open movable contact 62 actuated by a diaphragm 63 sensitive enough to be operable by blood pressures in the realm of 50 to 150 mm. of mercury against opposition of an adjustable light bias spring 64. Such pressure switch 56, shown schematically, may simply also comprise a casing defining a pressure chamber at one side of the diaphragm and an atmospheric chamber on the opposite side, which diaphragm is operable by an incompressible, non-conductive liquid pressurized in accord with the patients blood pressure by way of an isolation diaphragm 66 in a liquid-coupling device 67, which diaphragm is subject to switch-actuating liquid on one side and to the patients blood in a chamber 70 at its opposite side. The chamber 70, during operation of the apparatus, is hydraulically coupled to the patients arterial system as by insertion of a cannula in an artery of the patient, preferably remote from the aorta, as in the vicinity of the patients wrist, neck, or underarm. The

augmentation-termination control pressure switch device 75 may be similar to the augmentation-elfecting pressure switch device 56, but with a normally-closed contact 73 connected in series with the normally-open contact 62 of the latter device, both movable contacts being connected in series with the D-C source, and the winding of the solenoid valve device 5. Adjustment of the responsive characteristics of the two pressure switch devices 56 and 57 may be effected by the adjustment of the bias imposed by the springs 64 of the two devices as Well as by adjustment of the timing means in the form of respective needle valves 58 and 59 in the control communication leading from the output chamber 75 of the liquid-isolation device 67. To permit rapid recovery of the switch devices 56 and 57 to their normally-open and normally-closed positions, respectively, the respective pressure chambers 76 and 77 are connected to the chamber 75 in the liquid-isolation device 67 by way of check valves 80 and 81 which permit rapid release of liquid from such pressure chambers. Initially, priming of the blood chamber of the isolation device 67 and of the flexible tubing connected thereto is facilitated by a bleed port 82 at the uppermost part of such chamber, which is closed by a valve upon completion of such initial priming. Similarly, initial priming of the pressure chambers 76 and 77 in the pressure switch devices 56 and 57 and of the lines connected thereto is facilitated by a bleed port 83 at the top of the liquid chamber in the isolation device 67, and this also is closed following such initial priming by a suitable valve.

In operation of the blood pressure augmentation system of the present invention, the needle valve 58 and the bias spring 64 afliliated with the augmentation-effecting pressure switch device 56 are adjusted to energize the winding of the solenoid valve device 5 to effect local supply of compressed gas from the storage volume 3 to the chamber 40 at one side of the diaphragm 38 to effect displacement thereof and of the blood pump diaphragm 10 through the medium of the liquid in the cylindrical chamber 11 and corresponding deflection of the second diaphragm 10 to augment the diastolic arterial blood pressure by the displacement of blood from the conical chamber 12 at one side of the blood pumping diaphragm into the patients aorta. Such response of pumping of a quantity of blood into the aorta by virtue of energization of the solenoid valve means 5 will be substantially instantaneous and without undue delay, in spite of the fact that a compressible fluid is used for actuating the diaphragm 10, by virtue of the immediate adjacency of the storage chamber 3 which acts as a local source of supply of compressed gas. Following such energization of the solenoid valve means 5 by virtue of closure of the augmentationeifecting pressure switch device 56, the augmentation-terminating pressure switch device 57 will open at some point during the diastolic period of the patients heart beat, according to adjustment of the needle valve 59 and of the bias spring 64. Such opening of the pressure switch device 57 will etfect deenergization of the solenoid valve 5 to permit release of the pressurized gas in the chamber 40 at one side of the second diaphragm 38 to the atmosphere by way of a pneumatic connector 86 and port 46 in the solenoid valve means. This then permits the patients blood pressure to return to a pre-systolic pressure at the beginning of each heart beat. In response to each such reduction in arterial blood pressure between the heart beats, the successive reductions in blood pressure in the chamber 70 of the liquid isolation device 67 will permit the biased diaphragms 63 to displace liquid from the pressure chambers 76 and 77 of the switch devices 56 and 57 rapidly by way of the respective check valves and 81 in preparation for each successive diastolic pressure augmentation operation of the solenoid valve device 5. The patients blood pressure may be represented on an oscilloscope screen in order to facilitate the proper adjustment of the control apparatus of FIG. III in accord with the patients heart beat in order to obtain diastolic pressure augmentation. The amplitude of the degree of diastolic pressure augmentation desired can be adjusted by regulation of the pressure of the compressed gas stored chamber 3 as by inclusion of the regulating valve device 44 controlling the pressure admitted to such chamber from an external source such as bottled gas or an oxygen line in the hospital room; it being understood that the degree of displacement of blood from the conical chamber 12 is a function of the gas pressure obtained in the chamber 40 at the one side of the second diaphragm 33. By a suitable selection of the size of the local storage chamber 3 relative to the size of the pneumatic chamber 40 at the one side of the second diaphragm 38, together with such factors as the diameter of such diaphragm and its resiliency, response to pressurization of such pneumatic chamber 40 can be extremely rapid due to local pressure equalization which transpires each time such storage chamber 3 is connected to such pneumatic chamber by way of the solenoid valve means. During the time that the solenoid valve is venting the pneumatic chamber 40 to the atmosphere by way of the exhaust port 46 and an unseated vent valve in such solenoid valve means the supply valve of such solenoid valve means 5 will be closed and the storage chamber pressure 3 will be replenished by way of the supply port 90 connected thereto. In the usual case, the time for replenishment of the storage chamber 3 will be relatively large as compared to the period of use of compressed gas therefrom, inasmuch as the period of pressure augmentation during each cycle of the patients heart beat will be a relatively small percentage of such beat; only about 15 to of such beat.

While the system of the present invention has been described in connection with diastolic pressure augmentation in synchronism with a naturally beating heart of the patient, it will be apparent that the system can function in conjunction with assisting artificial pumping action imparted to a patients heart such as may be affected With either open or closed chest massaging techniques.

Although the invention has been described with a certain degree of particularity in connection with an illustrative embodiment thereof, it is desired that the appended claims cover modifications which may be apparent to those skilled in the art to which the invention pertains.

I claim as my invention:

1. A unitary blood pump apparatus comprising pump casing means defining a blood chamber; a resilient circular blood-pumping diaphragm clamped at its outer periphcry to said casing means, exposed on one face to said blood chamber, stretchable to displace blood from such blood chamber, and self-biased reversely for inducing return flow of blood to such blood chamber; means defining a pneumatic storage volume having a pneumatic inlet adapted for connection to a source of compressed gas; means defining a pneumatic actuating fluid chamber 83 operatively coupled to the opposite face of said bloodpumping diaphragm to effect alternate axial stretched displacement and return thereof responsively to establishment and dis-establishment of preponderance in pneumatic pressure in said actuating fluid chamber over diaphragm bias and blood pressure in the aforesaid blood chamber; valve means connected to said storage volume and to said actuating fluid chamber operable to alternately connect said actuating fluid chamber to said storage volume and to the atmosphere; and means including a common housing retaining all of the aforesaid means together in close proximity.

2. A blood pump apparatus as claimed in claim 1, further comprising means for controlling operation of the aforesaid valve means to effect cyclical operation of the blood-pumping diaphragm in synchronism with a patients heart beat.

3. A blood pump apparatus as set forth in claim 1, further comprising means for controlling operation of the aforesaid valve means to effect stretching deflection of the blood-pumping diaphragm during each diastolic period of a patients heart beat and self-biased-return of said bloodpumping diaphragm during each systolic period of such heart beat.

4. A blood pump apparatus as set forth in claim 1, further comprising a second flexible diaphragm and a chamber filled with a blood-compatible liquid interposed between said second diaphragm and said blood-pumping diaphragm.

5. A blood pump apparatus as set forth in claim 1, wherein said blood-pumping diaphragm is disc-shaped in its non-distended state, said pump casing means has a cylindrical portion onto which the outer periphery of said diaphragm fits, and said apparatus comprises a solid ring which may he slid on-and-oft in an axial direction during assembly and disassembly to provide for securing such diaphragm in a radially stretched condition.

References Cited UNITED STATES PATENTS 3,030,892 4/1962 Piccardo 103-440 3,039,399 6/1962 Everett 103-l50 3,099,260 7/1963 Birtwell 1281 3,183,908 5/1965 Collins et al 23258.5 3,204,631 9/ 1965 Fields l03-l50 X 3,208,448 9/1965 Woodward 128-l 3,266,487 8/1966 Watkins 128---l OTHER REFERENCES Goldfarb et al.: Treatment of Circulatory Failure With a New System for Selective Diastolic Augmentation. Surgery, vol. 56, No. 3, September 1964, pp. 547- 555.

DALTON L. TRULUCK, Primary Examiner.

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