CA1299454C - Venting apparatus and method for cardiovascular pumping application - Google Patents
Venting apparatus and method for cardiovascular pumping applicationInfo
- Publication number
- CA1299454C CA1299454C CA000577254A CA577254A CA1299454C CA 1299454 C CA1299454 C CA 1299454C CA 000577254 A CA000577254 A CA 000577254A CA 577254 A CA577254 A CA 577254A CA 1299454 C CA1299454 C CA 1299454C
- Authority
- CA
- Canada
- Prior art keywords
- heart
- liquid
- housing
- gases
- flexible conduit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
- A61B17/34—Trocars; Puncturing needles
- A61B17/3417—Details of tips or shafts, e.g. grooves, expandable, bendable; Multiple coaxial sliding cannulas, e.g. for dilating
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
- A61M1/3621—Extra-corporeal blood circuits
- A61M1/3627—Degassing devices; Buffer reservoirs; Drip chambers; Blood filters
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2202/00—Special media to be introduced, removed or treated
- A61M2202/02—Gases
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2210/00—Anatomical parts of the body
- A61M2210/10—Trunk
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2210/00—Anatomical parts of the body
- A61M2210/12—Blood circulatory system
- A61M2210/127—Aorta
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/10—Location thereof with respect to the patient's body
- A61M60/122—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body
- A61M60/126—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable via, into, inside, in line, branching on, or around a blood vessel
- A61M60/148—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable via, into, inside, in line, branching on, or around a blood vessel in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
Abstract
ABSTRACT This device relates to an improvement on mechanical enhancement of the pumping action of the human heart, which is achieved by an external venting source, such as a pump joined to an instrument insertable into a partient's heart or aorta and serving to vent excessive gases from the heart, thereby improving brain and lung functions in a closed-loop fashion, by improving the pumping ability of the human heart.
Description
V~NTING APPARATUS AND ~ETHOD FOR
CAR~IOVASCUI.AR PUMPIN~ APP~ICATION
~I8LD OF INVENTION
The present invention relate~, in part, to an apparatus and a method of operation associated therewith for a mechanical enhancement of the pumping action of the human hear~. More specifically, thi~ apparatus xelates to a method for venting exce~ive gase~ away from the heart.
BAC~GROUND TO THE INV~NTION
Heretofore, there have been many attempts to improve conditions associated with heart problem~. These have ranged from chemicals such ~s digitalis and diuretics to such devices as artificial valve~ and artificial hearts. The attempts over the years, however, do not appear to include the combined recognition of energy relationships, leakage of gas back into the ventricles, and the removal of ga~ a~ a means for improving the ability of a heart to pump liquid, that is, blood. This invention is directed toward obtaining and maintainin~ a stable heart condition with the present appar~tus as a means for that objective.
~ he heart dynamics, or more specifically the dynamics of one side of ~he heart, have become anaiytically describable as a fluid flow dynamic proce~s with an input flow, namely the return ~low; an output flow; and a difference between the input flow and output flow repr~enting the rate o~ chan~e of the amount of fluid within the heart at a given time.
To relate to the present invention the fluid must be con~idered to contain both gas and liquid. By varying the amounts ~L29~4 o~ the gas and liquid, chan~es in output flow can be produced.
If, for example, some of the gas at the entrance to the aorta is allo~ed to repea~edly leak back through the aortic valve, between each pulsation the amount of gas within the heart can build up and be repeatedly pumped and leaked back.
As the amount of gas pumped becomes greater the amount of liquid pumped becomes leqs. If carried very far, this process leads to a significant reduction in liquid flow, and an instability type of condition follows, somewhat representative of a heart arrhythmia condition.
To some extent the above description parallels an analysis of fluid control apparatuses, such as for aircraft engine fuel control systems, as in each case, both contain input signals, flow in, flow out and the like. Also, to some extent the above parallels that of some engines, again input signal~, flow in, and flow out as in a pumping action.
The heart action i8 basically that of a pump. Pumps work on an energy basis. When a pump i5 presented with a mixture of ~as and ~iquid, the pump has a preference ~or operation on a minimal energy basi~. ~e~s energy is required to pump a given volume o~ a ~as that to pump the same volume of a liquid.
Less energy is required to pump a ~iven volume of ~as through an orifice or restriction, and in the case of the heart, the orifice i~ the passage through a valve; both when the valve is properly open, and when the valve is damaged and supposed to be close but is actually partially open. If both a ~as and a liquid are available, the heart has a tendency to preferentially pump a volume of gas; thus, decreasing the volume of liquid that 1;~99~5~
can be pumped with a ~iven amount of energy in a ~iven amount of time.
If an outlet valve ig damaged, in such a manner as to leak, there is a tendency for gas to leak back throu~h the valve. The aortic valve, if damaged, can be such a valve. The gas can be preferentially pumped to the outlet side of the valve again and again, for a multitude of times.
The leaXing of gas back through defective heart valves, the process being repeated, has as a ramification a decrea~ing amount of liquid, that is, blood, being pumped. This vapor/llquid ratio situation can be very bad with a defective heart JUSt as with other forms of pumps, especially when the inlet pressure is very low even for very brief periods of time. In closed-loop sys~ems, an improved capability in an active component, such as the heart in this case, can improve the overall performance of the loop.
An example of the aforementioned i5 the case in which heart performance is represented by a ~roup of curves of pressure rise versus liquid volumetric flow rate with each curve represented by a different vapor/liquid ratio. Measurements may be in ter~s of weight flow rate or mass flow rate converted to liquid volumetric flow rate. Computerized regression methods are known and may be used to sort data, and perform related calculations, in such a manner a~ to describe the curves in terms oE constant vapor/llquid ratio spaced in equal increments of vapor/liquid ratio. Curves can also be established for other parts of the closed-loop, such as the lungs. The combined oxygen absorption rate o~ the two lung~ ver~us blood flow rate can be repre~ented by a curve. In an analytical sense, there is a subtle but important f actor involved in closed-loop systems herein explained. If component parts of the system, such as the heart and lun~s, are described by the aforementioned curves, approximate transfer fullctions may be established for both open-loop and closed-loop performance. With such transfer functions it can be shown, as an approximation, that the closed-ioop performance i9 related to the open-loop performance by a relationship of the following general form in Laplace transform notation:
Output KG(s) Closed loop gain - = _ Input 1 + KG(s) ~ where KG~s) represents the open-loop gain*
note that dividing numerator and denominator by KG~) gives:
Output Input ~ 1 KG( 9 ) The normal heart, as a component, represents substantial yain, in term~ of power ratio, pressure ratio, and flow ratio.
This is due to the ability o~ the heart to increase blood pressure and blood ~low rate in normal operat,ion. Excessive ~as as described above substantially reduces ~uch gain. In a close-loop syst,em, the performance of a single component, e.~., the heart, may vary considerably from its curve oE normal performance without a ~reat effect upon closed-loop performance as indicated by closed-loop gain. For example, as a first order ~29~
appr~ximation, for an open-loop ~ain of 10 for a hear~ a departure from the curve o~ component performance will have only one-tenth a9 much ef~ect on clo~ed-loop per~ormance ~9 it does on open-loop perfoxma~ce, a~ indicated by the above equation.
Althou~h, the variable ~G(~) can contain many ~actor~
representing the heart, lungs, arteries, veins, and the like--it is the heart thQt i~ a major factor with re~pect to ~ain--due to the pumpin~ action. With thi~ type o~ analy~is, the amoun~ of improvement expected for con~estive heart failure by ventin~ the gas can be e~timated. Also, this type of analy~i~ indicates that above normal or (superior) per~ormance, such as for athletes, etc. i5 dif~icult to achieve.
This invention relates to those apparatu~es and methods of ventina to reduce the vapor/liquid ratio and thereby improve , the capability of pumping liquid by the heart.
SUMMARY OF TIIE PRIOR ~RT
The ~ollowing cited reference~, both published and patented, are are ~ound to be exemplary o~ the U.S. p~ior art. They are:
,U.,S. ,P,a,t,ent lnYen~,or 4,625,712 Wampler 4,493,692 Reed 4.493,314 Edwflrds 4,385,637 ~khavi ~,355,950 Pollak 4,355,96~ RodibAu~h/Cobb 4,397,049 Robin~otl/K~trilaki~
3,592,183 Wa~kin~ et al 3,995,617 Watkin~ et al 4,01~,317 Hrutlo 4,309,637 Akhavi 4,3~9,994 Grunwald lZ994~j~
The above cited references contain a variety of deaeration features, constructions o~ Sel~ Priming Centrifugal Pumps, Gear Pump havin~ Fluid Deaeration Capability, Hydraulically Actuated Cardiac Prosthesis With Three-~ay Ventricular Valving and the like; ho~ever, the purposes of the above cited prior art are different from the present invention. Variou~ constructions of pumps have been known to incorporate similar features, as the device disclosed herein, but such pumps have been relate~ to applicationQ other than the heart.
Another prior art reference is the article "Designing a Simulated Laboratory" by Niles Peterson, pages 286 through ~96, June, 1~84, Byte Ma~azine, published by McGraw-Hill, Inc., Peterborough, New Hampshire 03458.
The illustration on page 294 for the simulation of the Otto Frank experiment of the year 1896 is of interest as the present invention, and it~ utilization, involvin~ dynamic closed-loop analysis and synthesis may be viewed as an improvement upon and a updating of the Otto Frank experiment.
One reference for closed-loop systemQ i~ the book "Automatic Feedback Control System synthe~is" by John G. Truxal, 1955, McGraw-Hill Book Company, Inc. While clos2d-loop system~ are not easily analyzed, the above book represents a relatively detailed and ri~orou3 treatment of clo~ed-loop techniques. Fortunately, as long as open-loop and closed-loop concept3 are generally understood, a detailed knowled~e of such things as transient respon~e, frequency response, stability criterion and imaginary axis i9 not necessary for a general understanding of the in~ention.
These patents or known prior art uses teach and disclose various types of deaeration devices of sorts and of various manufactures, and the like, as well as methods of their construction; but none of them, whether taken singly or in combination, disclose the specific details of the combination of the invention in such a way as to bear upon the claims of the present invention.
SUMMARY OF THE INVENTION
It is a feature of an embodiment of the present invention to temporarily improve the action of the heart so that other natural processes, usual medical treatments, and surgery can more effectively provide mending, healing and strengthening of the heart. Additionally, in conjunction with the above, the present apparatus can be utilized to improve heart action when the usual methodology, such as major surgery, would otherwise be impractical as, for example, with the elderly.
A feature of an embodiment of the present invention is to obtain and maintain skable heart conditions by applying the device such that excessive gases, such as carbon dioxide and oxygen, may be removed so as to effect a ~ower gas/liquid ratio in the bloodstream. The invention provides a method and apparatus for mechanical enhancement of the pumping action of the heart and improving conditions associated with heart problems, Eor example, congestive heart failure.
An embodiment o~ the present invention can provide for the maintenance of a balanced ratio of vapor to li~uid within the heart. A system of open-loop and ......
closed-loop energy relationships, i.e. between the lungs and heart is utilized whereby a small percentage improvement in lung capacity is possible. The invention may th~n become a tool by which a rebalancing of the system to new pressures, pulse rates, flows and so ~orth are involved as in automobile accident injuries or gunshot wounds, where excessive losses of blood have occurred.
Another feature of an embodiment of the present invention is to increase the flow of blood through the heart by decreasing the vapor/liquid ratio within the heart and the aorta.
A further feature of an embodiment of the present invention provides a means for the venting of excessive blood gases, excluding essential oxygen - especially that associated with red blood cells and hemoglobin - since some of the elements in the gases serve normal and necessary functions in the blood stream.
Yet another feature of an embodiment of the present invention is to function to vent gas in foam (i.e.
air bubbles).
A still further feature of an embodiment of the present invention provides a construction for a venting means which may be adaptable to use with animals (i.e.
dogs, cattle) and the like.
A still further feature of an embodiment of the present invention is to provide reduced power requirements for an artificial heart such that the latter's power packs and the pacemaker itself may be made smaller.
In accordance with an embodiment of the present invention there is provided an apparatus for mechanically ~2~L5~
enhancing heart functions thereby improving conditions associated therewith. The apparatus comprising in combination: an elongated hollow tubular housing having an inlet and an outlet and a tip adapted to punc-ture the skin;
filter means within the housing adequate to permit the passage of gases and prevent the passage of liquids into the housing; Plexible conduit means communicating with the interior of the housing for venting gases from the heart; the filter means being removably retained in the housing and replaceable without removing the housing tip from the skin; removable guide means within the flexible conduit means; attachment means for connecting pumping means to the flexible conduit means outside the skin to facilitate removal of gases; and stop means to hal-t flow through the flexible conduit; whereby to reduce the volume of gases pumped by the heart and increase the volume of liquid pumped.
In a particularly preferred form a check valve is provided in the flexible conduit means to prevent flow therethrough to the heart.
The flexible conduit means may discharge gases to a low pressure region within the body. Preferably, the conduit includes means for permitting observation of the flow therethrough to assure that an excess amount of liquid is not removed.
These, together with other features and advantages oE the invention, reside in the details of the process and the operation thereof, as is more fully hereinafter described and claimed. References are now made to drawings forming a part hereoP, wherein like numerals refer to like parts throughout.
- 8a -~3 ,,`~.
BRI~F DESCRIPTIONS OF T~ DRA~I~GS
Figure 1 i9 a block diagram în general form o~ the ba~ic arran~ement of one side of the heart and includes a de~ignation of the location of the vent per one embodiment.
Figure 2 is a block dia~ram for the left side of the heart and includes a designation of the location of the vent per the preferred embodiment.
Figure 3 is a block diagram for the right side of the heart and includes a designation of the location of the vent per another embodiment.
Figure q is a block diagram with another embodiment incorporating a liquid-gas ~eparator.
Figure 5 i9 a block diagram of the preferred embodiment, and may be uQed in conJunction with the other fiaures for a better understand of this invention.
Figure 6 i9 a pictorial cross-sectional dia~rammatic representation of some o~ the material presented in Figure 2 and Figure 5 ~or the left side of the natural heart and desigrlates some altern~te vent locationQ.
Fi~ure 7 is a pictorial dia~rammatic representation of some o~ the material presented in Fi~ure 2 for the left ~ide of a mechanical heart ~ith a malfunctioning aortic valve and designates ~ome additional ventlng locations.
Figure 8 is an enlarged view of a typical vent o~ Figure 2.
~ i~ure 9 is an enlarged view of a vent containing a porou~
insert allowing ga~es to flow out.
- ~
~ i~ure 10 is an enlaraed view of an alternate vent showing apparatus for helping to retain a proper position, especially with respect to the inside of the heart.
DESCRIPTION OF TH~ PREFERR~D EM~ODINENT
The system of Figure 1 includes a section of a heart including a valve 1 at the outlet of ventricle 2 and a valve 3 between the ventricle 2 and atrium 4. This figure i5 generally illustrative purposes and includes a means of venting 5, such as a pump. ~his block diagram is applicable to the natural heart and to the artificial heart. The operation and use of the means of venting 5 are herein described below.
The heart is widely known to function basically as a pump and is highly efficient for its size. Comparing the amount of blood pumped per unit time, with the amount of energy used or such pumping, the amount of energy required to pump a given volume of a gas is less than the amount required to pump the same volume of liquid (i.e., blood). This can become very significant when ~as accumulates in the heart. Thi~ gas can be contained in foam a~so. Gas can accumulate in the heart due to such factors as a defective valve a~ herein explained. The ener~y required for a given volume of ~as to flow through an ori~ice is less than required for the same volume of liquid, i.e., blood, to flow throu~h an orifice. The flow path through a defective heart valve constitutes such an orifice. In one sequence o~ events, the heart preferentially pumps gas more efficiently than liquid and, therefore, pumps some small volume of gas through the valve 1. During at least a portion of the pumping cycle some of the ~Z~5114~L
aa~ leaks back into the ventricle 2. Notice the energy relationship~ in both pumpin~ and leaking of the ventricle 2, after the ~as leaXs back, it i9 preferentially pumped a~ain.
This type of process can be repeated with larger amounts of gas being pumped. Eventually, the amount of ~as becomes 50 ~reat as to adversely affect the amount of liquid, i.e., blood, that is pumped through the valve. The preferential pumping can be associated, at least in part, by the theoretic nature of liquids and gases, wherein; within a partially clo~ed system, e.g., a heart ventricle and its correspondence valve, the density of gas is less than that of liquid, i.e., blood, such that the gas is disposed closer to the valve than is the liquid~ This permits gas to be pumped before some of the liquid and leaving less time for the remainin~ liquid to flow through the outlet valve during each pulsation. E~sentially, in this case, the muscle action on the liquid pushes the liquid against the ~as, forcing the ga~ out first. Therefore, in this type of situation, more ener~y i~ al~o required from the muscle to pump a given amount of liquid, than in thé case of a heart with a normal valve. q'his indicates a further reason why an increased amount of energy is required by the heart to pump a ~iven amount o~ uid. Consequenkly, for a given amount of energy the liquid pumping capability o~ the heart is reduced. With reduced li~uid flow the ability to sweep ~as away from the outlet side of the outlet valve is reduced, resultin~ in a greater leak back availability of ~as.
Consequently, the pumping of larger amounts of gas can occur.
With ~as flow into the inlet of the same side of the heart, the ~2~ 5A~
~as has to be pumped throuah in order to be in a position where it will leak back through the defective outlet valve, thereby bein~ repumped through the outlet valve. In this case, the vapor to liquid ratio passing throu~h the defective outlet valve affects the ener~y requirements for pumping a ~iven amount of liquid. In addition, if a high vapor to liquid ratio is pre~ent at an inlet to the heart, additional energy is required to pump a ~iven amount of liquid through the atrium and ventricle. Venting means 5 ~such as a pump) is used to break up the above pattern of events 50 that the heart pumps more liquid. ~ith this mech~nical assi~tance, the performance of the heart is significantly improved. This can result in further improvement~ throughout the body: wherein the heart, lungs, brain, eyes, arteries, blood vessels, capillaries, and other organs throughout the body are operating, at least in part, as a combination of closed-loop systems .
The system shown in Figure 2 is a descriptive illustration of Figure 1. The aortic valve 6 is at the outlet of the left ventricle 7 and the mitral valve 8 is between the left ventricle 7 and the left atrium 9. The vent 10a and vent 10b, i.e., an elon~ated tubular instrument with a hollow needle-like housing, are used to vent ~RS. Operation and use of Fi~ure 2 i~ similar to Figure 1 but is more specific with respect to the aortic valve 6, and the leEt ventricle 7. An example, oE the application of Figure 2, is the case of congestive heart ~ailure. With a defective aortic valve 6 and malfunctions of the left ventricle 7, gas can be repeatedly pumped, adversely affecting the volume of li~uid r i.e., blood, that can be pumped. One or more vents 1~9945~
lOa and/or lOb may be used. The use of two vents offers advantages over one vent, namely: (1) Auxiliary means, in the event a vent becomes clog~ed: (2) If the pres~ure difference across the vent i5 very low it may be difficult to initiate vent gas flow, ~3) Two vents offer the opportunity for more gas flow without increasing the flow cross-sectional area resulting in the removal of an exce~sive amount of liquid, blood, as well a~ gas.
During the use of round vents, the diameter of the minimum cross-section of the flow passa~e is approximately 0.01 inch to 0.06 inch; with stop means lla and llb available to stop the flow through the vents in the event liquid flow becomes exce~sive. As seen in Figure B, ~ knife-edged oval orifice 23 at the lower end of the needle-like housin~ with an intérnal diameter of approximately 0.02 inch flt the opening to the vent and opening into an approximately 0.06 inch diameter flow pa~a~e would be advanta~eous to prevent clogging. The differential pressure across the knife-edged orifice 23, working on any material tending to plug the~knife-ed~ed orifice, would tend to keep the orifice open. A more complex ernbodiment could take the form of a more catheter-like configuration with ~as venting provisions per this invention. Such an embodiment could incl~de provisions for being inserted through any readily accessible vein. See Figure 5, Fi~ure 8, and Fi~ure lO for further details.
The system of Figure 3 is for the right ~ide of the heart and is similar to Figure 2. A defective pulmonic valve 12, with or without a malfunctioning right ventricle, can result in an excessive amounts of ~as being pumped. The amount of liquid, : ~L299~54 i.e., blood being pumped, is reduced. The relationships amon~
energy, leaking, and pumping are similar to those explained in connection with Fiaure 2. The operation and use of the venting instruments, hereinafter referred to a~ vent members lOa, and lOb, stop means lla and stop meanq llb are similar to the corresponding parts in Fi~ure 2.
The system in Figure 4 illustrates an alternative embodiment wherein a means of liquid-aas separation 17 connected to the stop means lla. In this manner, guide element, said element ha~ing a plate for receivina a catheter 28, the stop means lla, and the means of liquid-gas separation 17, are connected in a series, wherein the mean~ of liquid-~as separation is used to assure that an excessive amount of liquid, i~e., blood, is not removed without being returned. The liquid can be returned to the blood stream via the return means 18. Figure 4 also shows a vacuum means 19 such as a pump connected to the means of liquid-~as separation 17. The optional vacuum means 19 is used to expedite the removal of ~as.
F~igure 5 depict~ the apparatu~ in its pre~erred embodiment wherein, venting i9 done at the left ventricle L10 through ~ent member lOa. The vent member lOa i~ connected in series with stop means lla. The stop means lla i9 connected, in turn, to the means of liquid-gas separation 17 which is connected to both the return means 18 and check valve 22. The check valve 22, in turn, is connected to optional vacuum meanq or pumping device 19. The arran~ement of Fi~ure 5 could be potentially significant with re~ard to application in connection with at least one form of con~estive heart failure. Venting of ga~e~ as previou~ly ~ LS~
described i~ the si~nificant function, e~pecially in the case of a defective aortic valve. Th~ affect of vapor to liquid ratio upon fluid flow capability is very pronounced, re~ardin~ an open-loop system with (l) a KG~ 5 ) term o a type representing a high ratio of heart outlet-pressure/inlet-pressure ratio and (21 a given amount of energy, as related to muscle capability. A high KG~s) term has an amplifying effect which makes the energy requirements highly sensitive to vapor/liquid ratio.
Consequently, a much greater amount of energy is required to pump a given amount of liquid, when the amount of vapor at the inlet i5 large. Similarly, with a large amount of vapor in the atrium, a comparatively large amount of energy is required to pump a ~iven amount of liquid. Decreasing the vapor/liquid ratio causes a relatively large improvement in liquid pumping capability with a ~iven amount of energy from the muscle. A similar kind of situation with reyard to pumping capability exists with excessive gas in the ventricle. As a result, ventin~ of ~as per this invention improves the vapor/liquid ratio and has a rela~ively lar~e, or magnified, effect upon the liquid pumping capability of the heart. Furthermore, as indicated in Figure 5 that venting per this method can be used as an altérnative application, namely as a last resort, in removing a person off a respirator. In this alternative application the removal of gasQs, per thi~
invention, helps to prevent an excessively high blood pres~ure by disallowing an exce~sive build up of the volume of gas and liquid within the heart. By pre~enting excessively high blood pre~sure, over a si~nificant period of time, the respirator weaning procesQ
~ 5~
i~ improved.
Figure 6 i~ a pictorial cross-sectional representation of the natural heart for the material presented in Figure~ 2 through 5. The venting members are placed in the locations as laheled.
Ven~ location L9a and vent location L9b are indicated. Other vent locations are indicated by alpha-numeric designators L10, L11, L12, L13 and L14. Operation(s) and use ~5) are as indicated in connection with descriptions of Figure 1 through Figure 10.
Fiaure 7 is a pictorial dia~rammatic representation of an artificial heart in use with the apparatus Figure 5. Parts are labeled with the same designations as the corresponding parts and locations in Figure 6.
Comparatively, venting with respect to the natural heart and ventin~ of the artificial heart type, it is apparent that a direct correlation lies between the two. Also, for-a better understanding notice that the artificial heart acts as a pump and that venting per the invention can be demonstrated under carefully controlled laboratory conditions for a pump. By making parts,,,of the pump or artificial heart of transparent materials, gas may be detected visually as e~ldenced by such items as bubbles, ga~ pockets, and foam. Pitting of one or more valves of the artificial heart or pump can be physical evidence of cavitation. Cavitation can also occur in the natural heart.
Cavitation is likely to occur where there i~ decreased cross-sectional area in the flow passage, such as due to deposits, and when either the artificial or natural heart produces a pressure pulse with a high peak systolic pressure, the peak systolic pressure produces a high total pressure in the fluid ~hich, in turn, produces a high velocity that results in a very low ~tatic pressure in the vicinity of the dacreased flow area. The ver~
lo~ static pressure is produced in accordance with Bernoulli's principle and when gas bubbles are present there i5 a small region in the fluid in which the bubble~ can expand and collapse violently, and, in the case of the natural heart, this violent action both irritates and dama~es the fluid passage surfaces, thereby possibly dislodging ~ome of the latter's deposits.
Fi~ure 8 i9 an enlar~ed view of the venting member 10a of Figure 2 and Figure 5. V~ntin~ member 10b of Figure 2 i5 essentially the same as 10a. The venting member 10a i5 fundamentally a hollow tube and has an aperture at tip 23 which is inserted into the aorta wall 25. As seen in the preferred embodiment of Fi~ure 5, the tip 23 of a catheter-type element is located inside the heart, e.~., the aortic wall 25. The hollow tube 24 extends through body wall 26 and skin 26a. The tube 24 i9 preferably ~omewhat flexible and made oE implantable metal or plastic. The flexibility allows for movement of the heart and movemént of the body. On a temporary or emer~ency basis, a lar~e hypodermic needle may be substituted for the venting element 10a.
Preferred dimen~ions are di~cussed in connection with Fi~ure 2.
Preferably, the tip 23 i.~ swaged and ground to form a ~mall knife-ed~ed oval orifice type aperture at the inlet of the tip.
The removable guide means 27 is optional and serves a~ support means for the hollow tube 24 durin~ insertion. A tube and tip sli~htly scaled up in si2e would permit faster venting and would be more sound ~tructurally. Guide element ~8 i~ u~ed to attach 1 ~ 5~
the venting member lOa to the stop means lla.
Figure 9 i~ an enlarged view of an alternate f~rm of the ventin~ member lOa o~ Figure 8. The ma2or difference between Figure 8 and Figure 9 is the incorporation o pvrou~ insert 30, e.g., filter means, used to a~ure that gas, withaut an exceqs of blood, i~ vented. The porous in~ert 30 i~ removably at~ached within the outer housina 33 which correspond~ apprvximately to venting member lOa of Figure 8. The porou~ insert 30 is held in place bet~een a rabbet-type fixture 33b and internal cylindrical sleeve 29. The gas is vented through ori~icets) 31, the porous insert 30, and internal cylindrical sleeve 29. The porous insert 30 may be made of porous metal, porous plastic, or porous ceramic. The porous in~ert 30 can be attached to internal cylindrical Rleeve 29 to facilitate removal and replacement of the porous insert 30.
Figure 10 shows apparatus for helping to retain the orifice 31 inside the heart. The tightening rod 34 has a threaded end 35 which removably attaches to matin~ threads 35 in outer housing 33. ,The cap 37 i~ attached to the tightening rod 3~. For an option to reduce the number of part~ the internal cylindrical sleeve 29, the CAp 34, and the tightening rod 34 can all be combined as a single unit. As the threads are tightened by rotating the tighten-ing rod 34 relative to the outer housing 33, the cap 37 engages against the open end of outer housing 33 and causes the housing to deform in the vicinity of preformed internal groove 38, forming retaining ridge 39. It i~ the function of retainin~ rid~e 39 acting again~t the inner 3ide of the heart wall 25 to help retain the end of outer hou~ing 33 ~ L5~
containina orifice 31 within the inside o~ the heart. To encompass locations such as vent location L9a and L9b of Fiqure 2, t.he heart i9 defined 90 as to include the region of the aorta near the aortic valve.
The foregoing is considered as illu3trative only of the principles of the invention. Further, since numerous modifications and chan~es will readily occur to those ~killed in the art, it is not desired to limit the invention to the exact construction and operation ~ho~n and described, and accordingly, all suitable modifications, and equivalents which may be resorted to, fall within the scope of the invention.
CAR~IOVASCUI.AR PUMPIN~ APP~ICATION
~I8LD OF INVENTION
The present invention relate~, in part, to an apparatus and a method of operation associated therewith for a mechanical enhancement of the pumping action of the human hear~. More specifically, thi~ apparatus xelates to a method for venting exce~ive gase~ away from the heart.
BAC~GROUND TO THE INV~NTION
Heretofore, there have been many attempts to improve conditions associated with heart problem~. These have ranged from chemicals such ~s digitalis and diuretics to such devices as artificial valve~ and artificial hearts. The attempts over the years, however, do not appear to include the combined recognition of energy relationships, leakage of gas back into the ventricles, and the removal of ga~ a~ a means for improving the ability of a heart to pump liquid, that is, blood. This invention is directed toward obtaining and maintainin~ a stable heart condition with the present appar~tus as a means for that objective.
~ he heart dynamics, or more specifically the dynamics of one side of ~he heart, have become anaiytically describable as a fluid flow dynamic proce~s with an input flow, namely the return ~low; an output flow; and a difference between the input flow and output flow repr~enting the rate o~ chan~e of the amount of fluid within the heart at a given time.
To relate to the present invention the fluid must be con~idered to contain both gas and liquid. By varying the amounts ~L29~4 o~ the gas and liquid, chan~es in output flow can be produced.
If, for example, some of the gas at the entrance to the aorta is allo~ed to repea~edly leak back through the aortic valve, between each pulsation the amount of gas within the heart can build up and be repeatedly pumped and leaked back.
As the amount of gas pumped becomes greater the amount of liquid pumped becomes leqs. If carried very far, this process leads to a significant reduction in liquid flow, and an instability type of condition follows, somewhat representative of a heart arrhythmia condition.
To some extent the above description parallels an analysis of fluid control apparatuses, such as for aircraft engine fuel control systems, as in each case, both contain input signals, flow in, flow out and the like. Also, to some extent the above parallels that of some engines, again input signal~, flow in, and flow out as in a pumping action.
The heart action i8 basically that of a pump. Pumps work on an energy basis. When a pump i5 presented with a mixture of ~as and ~iquid, the pump has a preference ~or operation on a minimal energy basi~. ~e~s energy is required to pump a given volume o~ a ~as that to pump the same volume of a liquid.
Less energy is required to pump a ~iven volume of ~as through an orifice or restriction, and in the case of the heart, the orifice i~ the passage through a valve; both when the valve is properly open, and when the valve is damaged and supposed to be close but is actually partially open. If both a ~as and a liquid are available, the heart has a tendency to preferentially pump a volume of gas; thus, decreasing the volume of liquid that 1;~99~5~
can be pumped with a ~iven amount of energy in a ~iven amount of time.
If an outlet valve ig damaged, in such a manner as to leak, there is a tendency for gas to leak back throu~h the valve. The aortic valve, if damaged, can be such a valve. The gas can be preferentially pumped to the outlet side of the valve again and again, for a multitude of times.
The leaXing of gas back through defective heart valves, the process being repeated, has as a ramification a decrea~ing amount of liquid, that is, blood, being pumped. This vapor/llquid ratio situation can be very bad with a defective heart JUSt as with other forms of pumps, especially when the inlet pressure is very low even for very brief periods of time. In closed-loop sys~ems, an improved capability in an active component, such as the heart in this case, can improve the overall performance of the loop.
An example of the aforementioned i5 the case in which heart performance is represented by a ~roup of curves of pressure rise versus liquid volumetric flow rate with each curve represented by a different vapor/liquid ratio. Measurements may be in ter~s of weight flow rate or mass flow rate converted to liquid volumetric flow rate. Computerized regression methods are known and may be used to sort data, and perform related calculations, in such a manner a~ to describe the curves in terms oE constant vapor/llquid ratio spaced in equal increments of vapor/liquid ratio. Curves can also be established for other parts of the closed-loop, such as the lungs. The combined oxygen absorption rate o~ the two lung~ ver~us blood flow rate can be repre~ented by a curve. In an analytical sense, there is a subtle but important f actor involved in closed-loop systems herein explained. If component parts of the system, such as the heart and lun~s, are described by the aforementioned curves, approximate transfer fullctions may be established for both open-loop and closed-loop performance. With such transfer functions it can be shown, as an approximation, that the closed-ioop performance i9 related to the open-loop performance by a relationship of the following general form in Laplace transform notation:
Output KG(s) Closed loop gain - = _ Input 1 + KG(s) ~ where KG~s) represents the open-loop gain*
note that dividing numerator and denominator by KG~) gives:
Output Input ~ 1 KG( 9 ) The normal heart, as a component, represents substantial yain, in term~ of power ratio, pressure ratio, and flow ratio.
This is due to the ability o~ the heart to increase blood pressure and blood ~low rate in normal operat,ion. Excessive ~as as described above substantially reduces ~uch gain. In a close-loop syst,em, the performance of a single component, e.~., the heart, may vary considerably from its curve oE normal performance without a ~reat effect upon closed-loop performance as indicated by closed-loop gain. For example, as a first order ~29~
appr~ximation, for an open-loop ~ain of 10 for a hear~ a departure from the curve o~ component performance will have only one-tenth a9 much ef~ect on clo~ed-loop per~ormance ~9 it does on open-loop perfoxma~ce, a~ indicated by the above equation.
Althou~h, the variable ~G(~) can contain many ~actor~
representing the heart, lungs, arteries, veins, and the like--it is the heart thQt i~ a major factor with re~pect to ~ain--due to the pumpin~ action. With thi~ type o~ analy~is, the amoun~ of improvement expected for con~estive heart failure by ventin~ the gas can be e~timated. Also, this type of analy~i~ indicates that above normal or (superior) per~ormance, such as for athletes, etc. i5 dif~icult to achieve.
This invention relates to those apparatu~es and methods of ventina to reduce the vapor/liquid ratio and thereby improve , the capability of pumping liquid by the heart.
SUMMARY OF TIIE PRIOR ~RT
The ~ollowing cited reference~, both published and patented, are are ~ound to be exemplary o~ the U.S. p~ior art. They are:
,U.,S. ,P,a,t,ent lnYen~,or 4,625,712 Wampler 4,493,692 Reed 4.493,314 Edwflrds 4,385,637 ~khavi ~,355,950 Pollak 4,355,96~ RodibAu~h/Cobb 4,397,049 Robin~otl/K~trilaki~
3,592,183 Wa~kin~ et al 3,995,617 Watkin~ et al 4,01~,317 Hrutlo 4,309,637 Akhavi 4,3~9,994 Grunwald lZ994~j~
The above cited references contain a variety of deaeration features, constructions o~ Sel~ Priming Centrifugal Pumps, Gear Pump havin~ Fluid Deaeration Capability, Hydraulically Actuated Cardiac Prosthesis With Three-~ay Ventricular Valving and the like; ho~ever, the purposes of the above cited prior art are different from the present invention. Variou~ constructions of pumps have been known to incorporate similar features, as the device disclosed herein, but such pumps have been relate~ to applicationQ other than the heart.
Another prior art reference is the article "Designing a Simulated Laboratory" by Niles Peterson, pages 286 through ~96, June, 1~84, Byte Ma~azine, published by McGraw-Hill, Inc., Peterborough, New Hampshire 03458.
The illustration on page 294 for the simulation of the Otto Frank experiment of the year 1896 is of interest as the present invention, and it~ utilization, involvin~ dynamic closed-loop analysis and synthesis may be viewed as an improvement upon and a updating of the Otto Frank experiment.
One reference for closed-loop systemQ i~ the book "Automatic Feedback Control System synthe~is" by John G. Truxal, 1955, McGraw-Hill Book Company, Inc. While clos2d-loop system~ are not easily analyzed, the above book represents a relatively detailed and ri~orou3 treatment of clo~ed-loop techniques. Fortunately, as long as open-loop and closed-loop concept3 are generally understood, a detailed knowled~e of such things as transient respon~e, frequency response, stability criterion and imaginary axis i9 not necessary for a general understanding of the in~ention.
These patents or known prior art uses teach and disclose various types of deaeration devices of sorts and of various manufactures, and the like, as well as methods of their construction; but none of them, whether taken singly or in combination, disclose the specific details of the combination of the invention in such a way as to bear upon the claims of the present invention.
SUMMARY OF THE INVENTION
It is a feature of an embodiment of the present invention to temporarily improve the action of the heart so that other natural processes, usual medical treatments, and surgery can more effectively provide mending, healing and strengthening of the heart. Additionally, in conjunction with the above, the present apparatus can be utilized to improve heart action when the usual methodology, such as major surgery, would otherwise be impractical as, for example, with the elderly.
A feature of an embodiment of the present invention is to obtain and maintain skable heart conditions by applying the device such that excessive gases, such as carbon dioxide and oxygen, may be removed so as to effect a ~ower gas/liquid ratio in the bloodstream. The invention provides a method and apparatus for mechanical enhancement of the pumping action of the heart and improving conditions associated with heart problems, Eor example, congestive heart failure.
An embodiment o~ the present invention can provide for the maintenance of a balanced ratio of vapor to li~uid within the heart. A system of open-loop and ......
closed-loop energy relationships, i.e. between the lungs and heart is utilized whereby a small percentage improvement in lung capacity is possible. The invention may th~n become a tool by which a rebalancing of the system to new pressures, pulse rates, flows and so ~orth are involved as in automobile accident injuries or gunshot wounds, where excessive losses of blood have occurred.
Another feature of an embodiment of the present invention is to increase the flow of blood through the heart by decreasing the vapor/liquid ratio within the heart and the aorta.
A further feature of an embodiment of the present invention provides a means for the venting of excessive blood gases, excluding essential oxygen - especially that associated with red blood cells and hemoglobin - since some of the elements in the gases serve normal and necessary functions in the blood stream.
Yet another feature of an embodiment of the present invention is to function to vent gas in foam (i.e.
air bubbles).
A still further feature of an embodiment of the present invention provides a construction for a venting means which may be adaptable to use with animals (i.e.
dogs, cattle) and the like.
A still further feature of an embodiment of the present invention is to provide reduced power requirements for an artificial heart such that the latter's power packs and the pacemaker itself may be made smaller.
In accordance with an embodiment of the present invention there is provided an apparatus for mechanically ~2~L5~
enhancing heart functions thereby improving conditions associated therewith. The apparatus comprising in combination: an elongated hollow tubular housing having an inlet and an outlet and a tip adapted to punc-ture the skin;
filter means within the housing adequate to permit the passage of gases and prevent the passage of liquids into the housing; Plexible conduit means communicating with the interior of the housing for venting gases from the heart; the filter means being removably retained in the housing and replaceable without removing the housing tip from the skin; removable guide means within the flexible conduit means; attachment means for connecting pumping means to the flexible conduit means outside the skin to facilitate removal of gases; and stop means to hal-t flow through the flexible conduit; whereby to reduce the volume of gases pumped by the heart and increase the volume of liquid pumped.
In a particularly preferred form a check valve is provided in the flexible conduit means to prevent flow therethrough to the heart.
The flexible conduit means may discharge gases to a low pressure region within the body. Preferably, the conduit includes means for permitting observation of the flow therethrough to assure that an excess amount of liquid is not removed.
These, together with other features and advantages oE the invention, reside in the details of the process and the operation thereof, as is more fully hereinafter described and claimed. References are now made to drawings forming a part hereoP, wherein like numerals refer to like parts throughout.
- 8a -~3 ,,`~.
BRI~F DESCRIPTIONS OF T~ DRA~I~GS
Figure 1 i9 a block diagram în general form o~ the ba~ic arran~ement of one side of the heart and includes a de~ignation of the location of the vent per one embodiment.
Figure 2 is a block dia~ram for the left side of the heart and includes a designation of the location of the vent per the preferred embodiment.
Figure 3 is a block diagram for the right side of the heart and includes a designation of the location of the vent per another embodiment.
Figure q is a block diagram with another embodiment incorporating a liquid-gas ~eparator.
Figure 5 i9 a block diagram of the preferred embodiment, and may be uQed in conJunction with the other fiaures for a better understand of this invention.
Figure 6 i9 a pictorial cross-sectional dia~rammatic representation of some o~ the material presented in Figure 2 and Figure 5 ~or the left side of the natural heart and desigrlates some altern~te vent locationQ.
Fi~ure 7 is a pictorial dia~rammatic representation of some o~ the material presented in Fi~ure 2 for the left ~ide of a mechanical heart ~ith a malfunctioning aortic valve and designates ~ome additional ventlng locations.
Figure 8 is an enlarged view of a typical vent o~ Figure 2.
~ i~ure 9 is an enlarged view of a vent containing a porou~
insert allowing ga~es to flow out.
- ~
~ i~ure 10 is an enlaraed view of an alternate vent showing apparatus for helping to retain a proper position, especially with respect to the inside of the heart.
DESCRIPTION OF TH~ PREFERR~D EM~ODINENT
The system of Figure 1 includes a section of a heart including a valve 1 at the outlet of ventricle 2 and a valve 3 between the ventricle 2 and atrium 4. This figure i5 generally illustrative purposes and includes a means of venting 5, such as a pump. ~his block diagram is applicable to the natural heart and to the artificial heart. The operation and use of the means of venting 5 are herein described below.
The heart is widely known to function basically as a pump and is highly efficient for its size. Comparing the amount of blood pumped per unit time, with the amount of energy used or such pumping, the amount of energy required to pump a given volume of a gas is less than the amount required to pump the same volume of liquid (i.e., blood). This can become very significant when ~as accumulates in the heart. Thi~ gas can be contained in foam a~so. Gas can accumulate in the heart due to such factors as a defective valve a~ herein explained. The ener~y required for a given volume of ~as to flow through an ori~ice is less than required for the same volume of liquid, i.e., blood, to flow throu~h an orifice. The flow path through a defective heart valve constitutes such an orifice. In one sequence o~ events, the heart preferentially pumps gas more efficiently than liquid and, therefore, pumps some small volume of gas through the valve 1. During at least a portion of the pumping cycle some of the ~Z~5114~L
aa~ leaks back into the ventricle 2. Notice the energy relationship~ in both pumpin~ and leaking of the ventricle 2, after the ~as leaXs back, it i9 preferentially pumped a~ain.
This type of process can be repeated with larger amounts of gas being pumped. Eventually, the amount of ~as becomes 50 ~reat as to adversely affect the amount of liquid, i.e., blood, that is pumped through the valve. The preferential pumping can be associated, at least in part, by the theoretic nature of liquids and gases, wherein; within a partially clo~ed system, e.g., a heart ventricle and its correspondence valve, the density of gas is less than that of liquid, i.e., blood, such that the gas is disposed closer to the valve than is the liquid~ This permits gas to be pumped before some of the liquid and leaving less time for the remainin~ liquid to flow through the outlet valve during each pulsation. E~sentially, in this case, the muscle action on the liquid pushes the liquid against the ~as, forcing the ga~ out first. Therefore, in this type of situation, more ener~y i~ al~o required from the muscle to pump a given amount of liquid, than in thé case of a heart with a normal valve. q'his indicates a further reason why an increased amount of energy is required by the heart to pump a ~iven amount o~ uid. Consequenkly, for a given amount of energy the liquid pumping capability o~ the heart is reduced. With reduced li~uid flow the ability to sweep ~as away from the outlet side of the outlet valve is reduced, resultin~ in a greater leak back availability of ~as.
Consequently, the pumping of larger amounts of gas can occur.
With ~as flow into the inlet of the same side of the heart, the ~2~ 5A~
~as has to be pumped throuah in order to be in a position where it will leak back through the defective outlet valve, thereby bein~ repumped through the outlet valve. In this case, the vapor to liquid ratio passing throu~h the defective outlet valve affects the ener~y requirements for pumping a ~iven amount of liquid. In addition, if a high vapor to liquid ratio is pre~ent at an inlet to the heart, additional energy is required to pump a ~iven amount of liquid through the atrium and ventricle. Venting means 5 ~such as a pump) is used to break up the above pattern of events 50 that the heart pumps more liquid. ~ith this mech~nical assi~tance, the performance of the heart is significantly improved. This can result in further improvement~ throughout the body: wherein the heart, lungs, brain, eyes, arteries, blood vessels, capillaries, and other organs throughout the body are operating, at least in part, as a combination of closed-loop systems .
The system shown in Figure 2 is a descriptive illustration of Figure 1. The aortic valve 6 is at the outlet of the left ventricle 7 and the mitral valve 8 is between the left ventricle 7 and the left atrium 9. The vent 10a and vent 10b, i.e., an elon~ated tubular instrument with a hollow needle-like housing, are used to vent ~RS. Operation and use of Fi~ure 2 i~ similar to Figure 1 but is more specific with respect to the aortic valve 6, and the leEt ventricle 7. An example, oE the application of Figure 2, is the case of congestive heart ~ailure. With a defective aortic valve 6 and malfunctions of the left ventricle 7, gas can be repeatedly pumped, adversely affecting the volume of li~uid r i.e., blood, that can be pumped. One or more vents 1~9945~
lOa and/or lOb may be used. The use of two vents offers advantages over one vent, namely: (1) Auxiliary means, in the event a vent becomes clog~ed: (2) If the pres~ure difference across the vent i5 very low it may be difficult to initiate vent gas flow, ~3) Two vents offer the opportunity for more gas flow without increasing the flow cross-sectional area resulting in the removal of an exce~sive amount of liquid, blood, as well a~ gas.
During the use of round vents, the diameter of the minimum cross-section of the flow passa~e is approximately 0.01 inch to 0.06 inch; with stop means lla and llb available to stop the flow through the vents in the event liquid flow becomes exce~sive. As seen in Figure B, ~ knife-edged oval orifice 23 at the lower end of the needle-like housin~ with an intérnal diameter of approximately 0.02 inch flt the opening to the vent and opening into an approximately 0.06 inch diameter flow pa~a~e would be advanta~eous to prevent clogging. The differential pressure across the knife-edged orifice 23, working on any material tending to plug the~knife-ed~ed orifice, would tend to keep the orifice open. A more complex ernbodiment could take the form of a more catheter-like configuration with ~as venting provisions per this invention. Such an embodiment could incl~de provisions for being inserted through any readily accessible vein. See Figure 5, Fi~ure 8, and Fi~ure lO for further details.
The system of Figure 3 is for the right ~ide of the heart and is similar to Figure 2. A defective pulmonic valve 12, with or without a malfunctioning right ventricle, can result in an excessive amounts of ~as being pumped. The amount of liquid, : ~L299~54 i.e., blood being pumped, is reduced. The relationships amon~
energy, leaking, and pumping are similar to those explained in connection with Fiaure 2. The operation and use of the venting instruments, hereinafter referred to a~ vent members lOa, and lOb, stop means lla and stop meanq llb are similar to the corresponding parts in Fi~ure 2.
The system in Figure 4 illustrates an alternative embodiment wherein a means of liquid-aas separation 17 connected to the stop means lla. In this manner, guide element, said element ha~ing a plate for receivina a catheter 28, the stop means lla, and the means of liquid-gas separation 17, are connected in a series, wherein the mean~ of liquid-~as separation is used to assure that an excessive amount of liquid, i~e., blood, is not removed without being returned. The liquid can be returned to the blood stream via the return means 18. Figure 4 also shows a vacuum means 19 such as a pump connected to the means of liquid-~as separation 17. The optional vacuum means 19 is used to expedite the removal of ~as.
F~igure 5 depict~ the apparatu~ in its pre~erred embodiment wherein, venting i9 done at the left ventricle L10 through ~ent member lOa. The vent member lOa i~ connected in series with stop means lla. The stop means lla i9 connected, in turn, to the means of liquid-gas separation 17 which is connected to both the return means 18 and check valve 22. The check valve 22, in turn, is connected to optional vacuum meanq or pumping device 19. The arran~ement of Fi~ure 5 could be potentially significant with re~ard to application in connection with at least one form of con~estive heart failure. Venting of ga~e~ as previou~ly ~ LS~
described i~ the si~nificant function, e~pecially in the case of a defective aortic valve. Th~ affect of vapor to liquid ratio upon fluid flow capability is very pronounced, re~ardin~ an open-loop system with (l) a KG~ 5 ) term o a type representing a high ratio of heart outlet-pressure/inlet-pressure ratio and (21 a given amount of energy, as related to muscle capability. A high KG~s) term has an amplifying effect which makes the energy requirements highly sensitive to vapor/liquid ratio.
Consequently, a much greater amount of energy is required to pump a given amount of liquid, when the amount of vapor at the inlet i5 large. Similarly, with a large amount of vapor in the atrium, a comparatively large amount of energy is required to pump a ~iven amount of liquid. Decreasing the vapor/liquid ratio causes a relatively large improvement in liquid pumping capability with a ~iven amount of energy from the muscle. A similar kind of situation with reyard to pumping capability exists with excessive gas in the ventricle. As a result, ventin~ of ~as per this invention improves the vapor/liquid ratio and has a rela~ively lar~e, or magnified, effect upon the liquid pumping capability of the heart. Furthermore, as indicated in Figure 5 that venting per this method can be used as an altérnative application, namely as a last resort, in removing a person off a respirator. In this alternative application the removal of gasQs, per thi~
invention, helps to prevent an excessively high blood pres~ure by disallowing an exce~sive build up of the volume of gas and liquid within the heart. By pre~enting excessively high blood pre~sure, over a si~nificant period of time, the respirator weaning procesQ
~ 5~
i~ improved.
Figure 6 i~ a pictorial cross-sectional representation of the natural heart for the material presented in Figure~ 2 through 5. The venting members are placed in the locations as laheled.
Ven~ location L9a and vent location L9b are indicated. Other vent locations are indicated by alpha-numeric designators L10, L11, L12, L13 and L14. Operation(s) and use ~5) are as indicated in connection with descriptions of Figure 1 through Figure 10.
Fiaure 7 is a pictorial dia~rammatic representation of an artificial heart in use with the apparatus Figure 5. Parts are labeled with the same designations as the corresponding parts and locations in Figure 6.
Comparatively, venting with respect to the natural heart and ventin~ of the artificial heart type, it is apparent that a direct correlation lies between the two. Also, for-a better understanding notice that the artificial heart acts as a pump and that venting per the invention can be demonstrated under carefully controlled laboratory conditions for a pump. By making parts,,,of the pump or artificial heart of transparent materials, gas may be detected visually as e~ldenced by such items as bubbles, ga~ pockets, and foam. Pitting of one or more valves of the artificial heart or pump can be physical evidence of cavitation. Cavitation can also occur in the natural heart.
Cavitation is likely to occur where there i~ decreased cross-sectional area in the flow passage, such as due to deposits, and when either the artificial or natural heart produces a pressure pulse with a high peak systolic pressure, the peak systolic pressure produces a high total pressure in the fluid ~hich, in turn, produces a high velocity that results in a very low ~tatic pressure in the vicinity of the dacreased flow area. The ver~
lo~ static pressure is produced in accordance with Bernoulli's principle and when gas bubbles are present there i5 a small region in the fluid in which the bubble~ can expand and collapse violently, and, in the case of the natural heart, this violent action both irritates and dama~es the fluid passage surfaces, thereby possibly dislodging ~ome of the latter's deposits.
Fi~ure 8 i9 an enlar~ed view of the venting member 10a of Figure 2 and Figure 5. V~ntin~ member 10b of Figure 2 i5 essentially the same as 10a. The venting member 10a i5 fundamentally a hollow tube and has an aperture at tip 23 which is inserted into the aorta wall 25. As seen in the preferred embodiment of Fi~ure 5, the tip 23 of a catheter-type element is located inside the heart, e.~., the aortic wall 25. The hollow tube 24 extends through body wall 26 and skin 26a. The tube 24 i9 preferably ~omewhat flexible and made oE implantable metal or plastic. The flexibility allows for movement of the heart and movemént of the body. On a temporary or emer~ency basis, a lar~e hypodermic needle may be substituted for the venting element 10a.
Preferred dimen~ions are di~cussed in connection with Fi~ure 2.
Preferably, the tip 23 i.~ swaged and ground to form a ~mall knife-ed~ed oval orifice type aperture at the inlet of the tip.
The removable guide means 27 is optional and serves a~ support means for the hollow tube 24 durin~ insertion. A tube and tip sli~htly scaled up in si2e would permit faster venting and would be more sound ~tructurally. Guide element ~8 i~ u~ed to attach 1 ~ 5~
the venting member lOa to the stop means lla.
Figure 9 i~ an enlarged view of an alternate f~rm of the ventin~ member lOa o~ Figure 8. The ma2or difference between Figure 8 and Figure 9 is the incorporation o pvrou~ insert 30, e.g., filter means, used to a~ure that gas, withaut an exceqs of blood, i~ vented. The porous in~ert 30 i~ removably at~ached within the outer housina 33 which correspond~ apprvximately to venting member lOa of Figure 8. The porou~ insert 30 is held in place bet~een a rabbet-type fixture 33b and internal cylindrical sleeve 29. The gas is vented through ori~icets) 31, the porous insert 30, and internal cylindrical sleeve 29. The porous insert 30 may be made of porous metal, porous plastic, or porous ceramic. The porous in~ert 30 can be attached to internal cylindrical Rleeve 29 to facilitate removal and replacement of the porous insert 30.
Figure 10 shows apparatus for helping to retain the orifice 31 inside the heart. The tightening rod 34 has a threaded end 35 which removably attaches to matin~ threads 35 in outer housing 33. ,The cap 37 i~ attached to the tightening rod 3~. For an option to reduce the number of part~ the internal cylindrical sleeve 29, the CAp 34, and the tightening rod 34 can all be combined as a single unit. As the threads are tightened by rotating the tighten-ing rod 34 relative to the outer housing 33, the cap 37 engages against the open end of outer housing 33 and causes the housing to deform in the vicinity of preformed internal groove 38, forming retaining ridge 39. It i~ the function of retainin~ rid~e 39 acting again~t the inner 3ide of the heart wall 25 to help retain the end of outer hou~ing 33 ~ L5~
containina orifice 31 within the inside o~ the heart. To encompass locations such as vent location L9a and L9b of Fiqure 2, t.he heart i9 defined 90 as to include the region of the aorta near the aortic valve.
The foregoing is considered as illu3trative only of the principles of the invention. Further, since numerous modifications and chan~es will readily occur to those ~killed in the art, it is not desired to limit the invention to the exact construction and operation ~ho~n and described, and accordingly, all suitable modifications, and equivalents which may be resorted to, fall within the scope of the invention.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for mechanically enhancing heart functions thereby improving conditions associated therewith, comprising in combination:
an elongated hollow tubular housing having an inlet and an outlet and a tip adapted to puncture the skin;
filter means within said housing adequate to permit the passage of gases and prevent the passage of liquids into said housing;
flexible conduit means communicating with the interior of said housing for venting gases from the heart;
said filter means being removably retained in said housing and replaceable without removing said housing tip from the skin;
removable guide means within said flexible conduit means;
attachment means for connecting pumping means to said flexible conduit means outside the skin to facilitate removal of gases; and stop means to halt flow through said flexible conduit;
whereby to reduce the volume of gases pumped by the heart and increase the volume of liquid pumped.
an elongated hollow tubular housing having an inlet and an outlet and a tip adapted to puncture the skin;
filter means within said housing adequate to permit the passage of gases and prevent the passage of liquids into said housing;
flexible conduit means communicating with the interior of said housing for venting gases from the heart;
said filter means being removably retained in said housing and replaceable without removing said housing tip from the skin;
removable guide means within said flexible conduit means;
attachment means for connecting pumping means to said flexible conduit means outside the skin to facilitate removal of gases; and stop means to halt flow through said flexible conduit;
whereby to reduce the volume of gases pumped by the heart and increase the volume of liquid pumped.
2. Apparatus of claim 1, including a check valve in said flexible conduit means to prevent flow therethrough to the heart.
3. Apparatus of claim 1, wherein said flexible conduit means discharges gases to a low pressure region within the body.
4. The apparatus of claim 1, further including means on said conduit permitting observing the flow therethrough to assure that an excess amount of liquid is not removed.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/098,226 US4834707A (en) | 1987-09-16 | 1987-09-16 | Venting apparatus and method for cardiovascular pumping application |
US98,226 | 1987-09-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1299454C true CA1299454C (en) | 1992-04-28 |
Family
ID=22268167
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000577254A Expired - Lifetime CA1299454C (en) | 1987-09-16 | 1988-09-13 | Venting apparatus and method for cardiovascular pumping application |
Country Status (8)
Country | Link |
---|---|
US (1) | US4834707A (en) |
JP (1) | JPH01145066A (en) |
CA (1) | CA1299454C (en) |
CH (1) | CH678277A5 (en) |
DE (1) | DE3831540A1 (en) |
FR (1) | FR2620337A1 (en) |
GB (1) | GB2209678B (en) |
MX (1) | MX168356B (en) |
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-
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- 1988-09-09 GB GB8821226A patent/GB2209678B/en not_active Expired - Fee Related
- 1988-09-13 MX MX012996A patent/MX168356B/en unknown
- 1988-09-13 CA CA000577254A patent/CA1299454C/en not_active Expired - Lifetime
- 1988-09-16 CH CH3475/88A patent/CH678277A5/fr not_active IP Right Cessation
- 1988-09-16 DE DE3831540A patent/DE3831540A1/en active Granted
- 1988-09-16 JP JP63232150A patent/JPH01145066A/en active Pending
- 1988-09-16 FR FR8812147A patent/FR2620337A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
CH678277A5 (en) | 1991-08-30 |
GB2209678B (en) | 1992-03-25 |
MX168356B (en) | 1993-05-19 |
JPH01145066A (en) | 1989-06-07 |
US4834707A (en) | 1989-05-30 |
FR2620337A1 (en) | 1989-03-17 |
GB8821226D0 (en) | 1988-10-12 |
DE3831540A1 (en) | 1989-04-06 |
DE3831540C2 (en) | 1993-06-24 |
GB2209678A (en) | 1989-05-24 |
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Effective date: 19970428 |