Patent Application
20060142633
The present invention relates generally to a blood pumping system and procedure for supplementing blood circulation, in particular, to a system which supplements blood perfusion in distal regions of the patient's circulatory system at normal and/or elevated pressures.
There has been a pressing need for a device that is capable of supplementing blood perfusion in distal parts of a patient's circulatory system. It is common in patients suffering from Congestive Heart Failure (“CHF”), diabetes, gangrene, erectile dysfunction, atheroma or obstructive vessel disease to also suffer from poor circulation. Poor circulation often leads to a patient suffering from ischaemia or chronic oxygen debt in distal regions of their circulatory system. It is this ischaemia or oxygen debt that can lead to exercise related claudication or rest pain. These diseases may also lead to various other complications that may require radical surgery to correct, such as amputation of limbs. The present invention seeks to address these problems.
Traditionally, poor circulation in limbs has been treated by a wide range of devices and procedures, which were aimed at promoting blood flow through a limb and by doing so, induce revascularisation of the limb.
In the past, hyperbaric chambers have been used to increase oxygen tension within the limbs. This increases oxygen tension delivered to distal regions of the patient's circulatory system and leads to a reduction of oxygen debt in these regions. Hyperbaric chambers are often expensive, inefficient, reduce the patient's quality of life and are suitable only for short term use.
It is an object of the present invention to address or ameliorate one or more of the abovementioned disadvantages and to address the problem of supplementing blood perfusion in at least a distal region of the patient's circulatory system.
Accordingly to a further broad form of the present invention, there is provided a blood pumping system, for supplementing distal blood perfusion, comprising: a blood pressure altering device including an upstream end and a downstream end; wherein said blood pressure altering device cooperates with a circulatory system to promote blood flow throughout at least one or more distal regions including limbs, a brain region or a pelvic region of a patient by altering vascular blood pressure; whereby said blood pressure altering device, when in use, is positioned in series with the normal blood flow of the circulatory system of a patient.
Preferably, the blood pressure altering device, when in use, increases blood pressure in a localised region and the blood pressure altering device may also be a blood pump.
Preferably, the system provides a means of vascular regeneration, when in use.
Preferably, the blood pressure altering device may also be a blood pump. The blood pump may comprise an inlet and an outlet for connection to the circulatory system of a patient. The inlet may also be connected to an arterial system of the patient or the inlet may be connected to a venous system of the patient. The outlet may be connected to an arterial system of the patient. The inlet or outlet may also include cannula extensions to allow variable positioning of the blood pump. The preferred blood pump is also implantable within the body of a patient. Said system may also include an implantable power source and implantable controller both to cooperate with said blood pump.
Preferably, the blood pump has a relatively flat H-Q curve characteristic and is capable of delivering a relatively constant mean blood pressure and said blood pressure may be relatively accurately determined by pump speed without the need for an implanted sensor.
The system may include a flow-back shunt to allow blood to flow from an outlet of the blood pump back to an inlet of the blood pump. Said flow-back shunt may include a flow resistor that is capable of restricting blood flow through flow-back shunt. Said flow resistor may be regulated externally relative to the patient. Said system may also include at least one fistula, when in use, connected between the outlet and a desired site in the venous system to allow blood flow communication between said outlet and said site in the venous system. Said fistula may include a variable regulator for controlling blood rate within said fistula.
Said system may supplement distal blood perfusion on either a short term basis or a long term basis.
Said blood pump may also be positioned external to the body of the patient.
It is preferred that said system may also be supplemented by a regime of pharmaceuticals given to the patient that promote revascularisation of distal regions of blood circulation. Said system may be supplemented by a regime of pharmaceuticals given to the patient that promote vascular dilatation of distal regions and neovascularisation of patient's circulatory system.
Preferably, the circulatory system may be reinforced with stenting.
The preferred system may include at least one sensor to measure effectiveness of supplementing distal blood perfusion. The blood pressure altering device may include at least one additional outlet for connection to a haemodialysis system.
Accordingly to a further broad form of the present invention, there is provided a blood pumping system, for perfusing a distal region of a patient's circulatory system, comprising: a blood pressure altering device, wherein said blood pressure altering device is in fluid communication with said circulatory system, and wherein said blood pressure altering device pumps blood so as to create a localised hypertensive region in said distal region. Preferably, said distal region includes a portion of the arterial blood supply of the circulatory system.
Preferably, said blood pressure altering device is located in a position remote from the heart of the patient.
It is preferable for said system supply a continuous supra-systolic pressure in both systole and diastole and that said blood pressure altering device may be positioned in series with the normal blood flow of a circulatory system.
Preferably, said localised hypertensive region may be created downstream from the blood pressure altering device. Additionally, the blood pressure altering device may be a pump. Said pump may be implantable within the body of a patient and have a relatively flat flow pressure curve characteristic.
Preferably, said system provides a means of vascular regeneration and may also include a flow resistor.
Embodiments of the invention will now be described with reference to the drawings in which:
The aim of the embodiments of the present invention is to increase the input blood pressure to a limb of a mammal, usually a human patient. By locally increasing the blood pressure, a greater pressure gradient is generated in a distal region of the patient's circulatory system (in this embodiment the distal region is a limb of the patient 15) and thereby greater blood flow is encouraged within the limb. Increased local blood pressure also increases the partial pressures of the dissolved oxygen leading to better tissue nutrition. The oxygen debt and toxic metabolites that have accumulated are therefore decreased.
This increased perfusion is intended to promote healing, encourage development of co-lateral vessels and may reduce other associated symptoms, such as ulceration and pain. The aim is to create a localised area of hypertension at the upper part of the limb arterial system to reverse ischemic changes.
In the lower limbs of a human patient there are three distal compartments. These are the anterior tibial, posterior tibial and peroneal compartments. In peripheral vascular disease, there are different numbers and sizes of collaterals. Embodiments of the present invention achieve this by locally increasing the blood pressure and thereby increasing blood flow throughout the largest cross compartment collaterisation. This effect also may increase with increased perfusion pressure generated by the embodiment.
Preferably, an optimal collateral flow generally occurs at steady input pressures. The preferred embodiments of the present invention may increase in all three parameters; ie: systolic, mean and diastolic pressures are sought to be achieved.
An increase in the mean blood pressure within a limb or distal region of the circulatory system may improve neovascularisation. Preferred embodiments of the present invention may create localised areas of hypertension and thereby vascular neogenesis is stimulated, resulting in an improved blood flow circulation throughout the limb.
The first preferred embodiment of the invention applied to a human patient 15 is shown in
In this preferred embodiment of the present invention, the blood pressure altering device may be a blood pump 1. Specifically, the blood pump 1 may be a centrifugal rotary blood pump, which is implantable within the body of a patient 15. The preferred blood pump may also have a relatively flat H-Q curve to allow the pressure output to be accurately determined from only the power inputted into said pump 1.
In
Also, in this preferred embodiment of the present invention, the common iliac artery 2, which is downstream of the abdominal aorta 3, of patient 15 is severed at position 14. The inlet 10 of said pump 1 is then connected to the upstream portion of the common iliac artery 2 by connection means 16. This connection means 16 is preferably accomplished by either use of sutures, expanding stents, bio-glue and or adhesive.
Additionally, the downstream portion of the blood pump 1 has an outlet 9. In this preferred embodiment, this outlet 9 is connected to an external iliac artery 5 by connection means 17. This connection means 17 is preferably accomplished by the use of sutures, expanding stents, bio-glue and/or adhesive.
The severance of artery 2 at position 14 results in two ends of the artery being formed. In this preferred embodiment, as earlier stated, the upstream end is connected to pump 1. The downstream end of the artery, adjacent to the internal iliac artery 4, is not connected and left as a free end. This free end should be sealed to prevent blood leakage into internal body cavities of the patient.
In this preferred embodiment of the present invention the artery delivers blood to blood pump 1 and the blood pump pressurises the blood into artery 5, which in turn may increase the blood pressure and blood flow in the profunda femoris artery 7, common femoris artery, superficial femoral artery 8, internal iliac artery 4 and the external iliac artery 5. In doing so, this preferred embodiment induces a localised hypertensive state in at least a portion of the desired limb. In
Additionally, it is envisaged that inlet 10 and outlet 9 may include an expandable stent which may allow the pump to be positioned at a different site in the body rather than proximal to artery 2 and 5. Also, it is envisaged that connections sites between the inlet 10 and the artery 2 and outlet 9 with artery 5 can be reinforced by stenting the artery to prevent collapse or rupture. This is particularly relevant as the increased blood flow and pressure in the localised area may cause either one of these situations to occur.
Please note that in the embodiment shown in
In
Preferably, said flow back shunt 13 includes a flow back resistor 18 that is capable of restricting the blood flow through said flow back shunt 13. This resistor 18 preferably may be regulated by an external means.
Preferably, the blood flow through fistula 11 may be controlled by a variable regulator 14. Thereby the variable regulator 14 may control the reduction of undesirably high blood pressures.
Embodiments of the present invention may also include a blood pump that is attached to a venous system of the patient. The result would be that the change in blood pressure caused by the blood pump connected to circulatory system may pull blood through the limb as opposed to the aforementioned preferred embodiments that push the blood through the circulation system within the limbs by increasing blood pressure.
Also, multiple blood pumps may be implanted within a patient's circulatory system to allow multiple regions of localised hypertension within the patient.
Additionally, it may be beneficial to include within any of the preferred embodiments at least one sensor to detect and record blood pressure, blood flow or status information relating to the pump 1. Embodiments of the present invention may also include: a blood pump with multiple outlet which may be connected to arteries supplying respective multiple limbs.
Embodiments of the present invention may also be supplemented by the use of an appropriate regime of pharmaceuticals that promote vascular dilation of the distal regions of the circulatory system.
It is important to note that the present invention may function in a similar way if the pumping system was arranged to supplement blood flow in other distal regions of the circulatory system such as the arms, the legs, the pelvic region and/or the brain region.
Another preferred embodiment of the present invention includes a blood hyper-perfusion pumping system for supplementing flow, wherein said system creates a lower relative mean blood pressure at a cardiac side of a pumping device and a higher relative mean blood pressure at a distal ischaemic side. This system preferably is connected to the patient's circulatory system on the arterial side of said system.
Various modifications and alterations are possible within the spirit of the foregoing specification and drawings without departing from the scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 60434473 | Dec 2002 | US | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU03/01679 | 12/17/2003 | WO | 12/14/2005 |
