US20090105631A1 - Systems and methods for controlling renovascular perfusion - Google Patents

Abstract

Devices, systems and methods by which the real or apparent renovascular perfusion and intrarenal pressure may be selectively and controllably increased. By selectively and controllably increasing renovascular perfusion and interstitial hydrostatic pressure when the heart is unable to pump sufficient blood or when renal perfusion is suboptimal, the present invention reduces or reverses neurohormonal activation and fluid retention, and thereby minimizes their deleterious effects on the heart, vasculature, kidneys and other body systems.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
• The present application is a continuation of U.S. patent application Ser. No. 10/453,678, filed Jun. 2, 2003, which is a divisional of U.S. patent application Ser. No. 09/702,089, filed Oct. 30, 2000, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
• The present invention generally relates to medical devices and methods of use for the treatment and/or management of cardiovascular and renal disorders. Specifically, the present invention relates to devices and methods for controlling renal perfusion in the renovascular system for the treatment and/or management of cardiovascular disorders such as hypertension and congestive heart failure, and renal disorders such as renal insufficiency and end stage renal disease.
• Cardiovascular disease is a major contributor to patient illness and mortality. It also is a primary driver of health care expenditure, costing more than $326 billion each year in the United States. Hypertension, or high blood pressure, is a major cardiovascular disorder that is estimated to affect over 50 million people in the United States alone. Of those with hypertension, it is reported that fewer than 30% have their blood pressure under control. Hypertension is a leading cause of heart failure and stroke. It is the primary cause of death in over 42,000 patients per year and is listed as a primary or contributing cause of death in over 200,000 patients per year in the U.S. Accordingly, hypertension is a serious health problem demanding significant research and development for the treatment thereof.
• Hypertension occurs when the body's smaller blood vessels (arterioles) constrict, causing an increase in blood pressure. Because the blood vessels constrict, the heart must work harder to maintain blood flow at the higher pressures. Although the body may tolerate short periods of increased blood pressure, sustained hypertension may eventually result in damage to multiple body organs, including the kidneys, brain, eyes and other tissues, causing a variety of maladies associated therewith. The elevated blood pressure may also damage the lining of the blood vessels, accelerating the process of atherosclerosis and increasing the likelihood that a blood clot may develop. This could lead to a heart attack and/or stroke. Sustained high blood pressure may eventually result in an enlarged and damaged heart (hypertrophy), which may lead to heart failure.
• Heart failure is the final common expression of a variety of cardiovascular disorders, including ischemic heart disease. It is characterized by an inability of the heart to pump enough blood to meet the body's needs and results in fatigue, reduced exercise capacity and poor survival. It is estimated that approximately 5,000,000 people in the United States suffer from heart failure, directly leading to 39,000 deaths per year and contributing to another 225,000 deaths per year. It is also estimated that greater than 400,000 new cases of heart failure are diagnosed each year. Heart failure accounts for over 900,000 hospital admissions annually, and it is the most common discharge diagnosis in patients over the age of 65 years. It has been reported that the cost of treating heart failure in the United States exceeds $20 billion annually. Accordingly, heart failure is also a serious health problem demanding significant research and development for the treatment and/or management thereof.
• End stage renal disease (ESRD) affects over 300,000 people in the United States, with an annual incidence of over 79,000. Death from ESRD occurred in over 60,000 cases in 1998; the five year survival rate is less than 30%. Medicare payments in 1998 for the treatment of ESRD exceeded $10 billion. Accordingly, ESRD is a major health problem demanding improved therapy and management.
• Heart failure results in the activation of a number of body systems to compensate for the heart's inability to pump sufficient blood. Many of these responses are mediated by an increase in the level of activation of the sympathetic nervous system as well as activation of multiple other neurohormonal responses. Generally speaking, this sympathetic nervous system activation signals the heart to increase heart rate and force of contraction to increase the cardiac output; it signals the kidneys to expand the blood volume by retaining sodium and water; and it signals the arterioles to constrict to elevate to the blood pressure. The cardiac, renal and vascular responses increase the workload of the heart, further accelerating myocardial damage and exacerbating the heart failure state. Accordingly, it is desirable to reduce the level of sympathetic nervous system and other neurohormonal activation in order to stop or at least minimize this vicious cycle and thereby treat or manage the heart failure.
• A number of drug treatments have been proposed for the management of hypertension, heart failure and other cardiovascular and renal disorders. These include vasodilators to reduce the blood pressure and ease the workload of the heart, diuretics to reduce fluid overload, inhibitors and blocking agents of the body's neurohormonal responses, and other medicaments.
• Various surgical procedures have also been proposed for these maladies. For example, heart transplantation has been proposed for patients who suffer from severe, refractory heart failure. Alternatively, an implantable medical device such as a ventricular assist device may be implanted in the chest to increase the pumping action of the heart. Alternatively, an intra aortic balloon pump may be used for maintaining heart function for short periods of time, but typically no longer than one month. Other surgical procedures are available as well.
• Although each of these alternative approaches is beneficial in some ways, each of the therapies has its own disadvantages. For example, drug therapy is often incompletely effective. Some patients may be unresponsive (refractory) to medical therapy. Drugs often have unwanted side effects and may need to be given in complex regimens. These and other factors contribute to poor patient compliance with medical therapy. Drug therapy may also be expensive, adding to the health care costs associated with these disorders. Likewise, surgical approaches are very costly, may be associated with significant patient morbidity and mortality and may not alter the natural history of the disease. Accordingly, there continues to be a substantial and long felt need for new devices and methods for treating and/or managing high blood pressure, heart failure and renal disease, as well as their associated complications.
BRIEF SUMMARY OF THE INVENTION
• The present invention provides a number of devices, systems and methods by which the real or apparent renovascular perfusion and the renal interstitial hydrostatic pressure may be selectively and controllably increased. By selectively and controllably increasing renovascular perfusion and interstitial hydrostatic pressure when the heart is unable to pump sufficient blood or when renal perfusion is otherwise suboptimal, the renal system does not experience the reduced perfusion. Because the renal system does not experience the reduced perfusion, it does not initiate or contribute to, and may reduce the neurohormonal activation normally caused by reduced cardiac output and suboptimal renal perfusion, nor does it begin or continue, and could reverse the process of sodium and water retention that also would otherwise result. Thus, by selectively and controllably increasing renovascular perfusion during periods of decreased cardiac output or suboptimal renal perfusion, the present invention reduces or reverses neurohormonal activation and fluid retention, and thereby minimizes their deleterious effects on the heart, vasculature, kidneys and other body systems.
• In the case of end stage renal disease (ESRD), the present invention provides a number of devices, systems and methods by which renal perfusion and pressure can be increased, thereby restoring or augmenting perfusion of the kidney and blood filtration. In addition, by increasing renal perfusion, the present invention increases interstitial pressure to reduce sodium and water reabsorption, which have been shown to be interrelated.
• In an exemplary embodiment, the present invention provides a method of treating a patient utilizing a blood perfusion modification device, one or more physiologic sensors, and a control system. The blood perfusion modification device may be positioned in the renovascular circulation or immediately adjacent thereto. The sensor is preferably positioned in a renal artery or upstream thereof, but may also be placed in, on or adjacent the patient to generate a signal indicative of the need to modify renal perfusion. For example, the sensor may be positioned in a kidney, a renal artery or vein or adjacent thereto to generate a signal indicative of arterial blood perfusion, renal venous pressure or renal interstitial pressure. The blood perfusion modification device may be activated, deactivated or otherwise modified as a function of the sensor signal to cause or simulate a change, and preferably an increase, in renal perfusion and/or pressure. This method may be used to treat a number of clinical conditions including congestive heart failure, hypertension, renal failure, cardiovascular abnormalities, and the like. In each instance, the method may include the initial step of diagnosing or monitoring the clinical condition or a symptom or sign thereof, and thereafter providing treatment as needed.
• The present invention also provides a system including a blood perfusion modification device (e.g., a flow regulator, a flow redirector or a pump), a physiologic sensor (e.g., a transducer or a gauge), and a control system operably connected to both. The blood perfusion modification device is preferably positioned in the renovascular circulation. The control system (or a portion thereof) may be implanted or carried externally by the patient. In the closed loop mode, the sensor generates a sensor signal indicative of the need to modify renovascular perfusion, and the control system generates a control signal to activate the modification device as a function of the sensor signal to thereby modify the renovascular circulation. In the open loop mode, which may or may not utilize feedback from the sensor, the control system generates a control signal to activate the modification device as dictated by, for example, a pre programmed algorithm, the patient or the physician.
• The sensor may comprise, for example, a piezoelectric pressure transducer, an ultrasonic flow velocity transducer, a thermodilution flow transducer, or a strain gauge. As such, the sensor may generate a signal indicative of pressure (e.g., mean, systolic, diastolic or pulse), blood flow velocity, vasoactivity, or other fluid dynamic property. Alternatively, the sensor may measure the blood concentration of a component (e.g., sodium, renin, etc.) or an arterial/venous difference in concentration of the component.
• The blood perfusion modification device may comprise a flow regulator positioned in a renal vein or immediately downstream thereof to create backpressure in the renovascular circulation. Alternatively, the blood perfusion modification device may comprise a flow redirector positioned downstream of a renal artery to redirect blood flow to the renal artery. As a further alternative, the blood perfusion modification device may comprise a pump. The pump may be positioned upstream of a renal artery to supplement blood flow to the renal artery or positioned downstream of a renal vein to supplement blood flow from the renal vein. As yet a further alternative, the blood perfusion modification device may comprise a drug delivery device. In each of these embodiments, the blood perfusion modification device may be positioned intravascularly or extravascularly. By way of example, not limitation, the blood perfusion modification device may comprise an inflatable cuff, a rotatable ring, a hydraulic piston, a solenoid, an inflatable balloon, or a drug delivery device.
• The control system may include a processor and memory. The memory may include software containing one or more algorithms defining one or more functions or relationships between the control signal and the sensor signal. The algorithm may dictate activation or deactivation control signals depending on the sensor signal or a mathematical derivative thereof. The algorithm may dictate an activation or a deactivation control signal when the sensor signal falls below a lower predetermined threshold value, rises above an upper predetermined threshold value or when the sensor signal indicates a specific physiologic event.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic illustration of the renovasculature and associated anatomy;
• FIG. 2 is a schematic illustration of a renal vein flow regulator system in accordance with the present invention;
• FIG. 3 is a schematic illustration of a flow redirection system in accordance with the present invention;
• FIG. 4 is a schematic illustration of an arterial flow pump system in accordance with the present invention;
• FIG. 5 is a schematic illustration of a venous flow pump system in accordance with the present invention;
• FIGS. 6A and 6B are side cross sectional schematic illustrations of an extraluminal flow regulator/redirector in the form of an inflatable cuff in accordance with the present invention, shown in the deactivated (unconstricted) and activated (constricted) states, respectively;
• FIGS. 7A and 7B are side cross sectional schematic illustrations of an intraluminal flow regulator/redirector in the form of an inflatable balloon in accordance with the present invention, shown in the deactivated (unconstricted) and activated (constricted) states, respectively;
• FIGS. 8A and 8B are side cross sectional schematic illustrations of an extraluminal flow regulator/redirector in the form of a hydraulic piston or solenoid in accordance with the present invention, shown in the deactivated (unconstricted) and activated (constricted) states, respectively;
• FIGS. 9A and 9B are side cross sectional schematic illustrations of an extraluminal flow regulator/redirector in the form of a rotatable ring in accordance with the present invention, shown in the deactivated (unconstricted) and activated (constricted) states, respectively;
• FIG. 10 is a side cross sectional schematic illustration of an extraluminal flow supplementor/pump in the form of a series of balloons or solenoids in accordance with the present invention, shown in the deactivated (unconstricted) state;
• FIG. 11 is a side cross sectional schematic illustration of an intraluminal flow supplementor/pump in the form of an impeller in accordance with the present invention; and
• FIG. 12 is a side cross sectional schematic illustration of an extraluminal site to specific drug delivery apparatus.
DETAILED DESCRIPTION OF THE INVENTION
• The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.
• Refer now toFIG. 1 which is a schematic illustration of therenal system10 of an adult human. The right and left sides of therenal system10 are substantially symmetrical and are identified by the letters R and L, respectively. Blood is supplied to the kidneys12 by way of the descendingaorta14 and the renal arteries20. Blood is removed from the kidneys12 by way of theinferior vena cava16 and the renal veins22.
• The descendingaorta14 bifurcates downstream into the common iliac arteries28. The direction of the arterial blood flow in the descendingaorta14 is indicated byarrows24, and the direction of the venous blood flow in theinferior vena cava16 is indicated byarrows26. Waste products are removed from the blood by the kidneys12 and transported to the bladder (not shown) by way of ureters18.
• As stated previously, a number of body systems are activated to compensate for the heart's inability to pump sufficient blood or in the presence of renal disease or restricted renal perfusion (e.g., renal artery stenosis causing hypertension and/or renal disease). In the case of heart failure, therenal system10 senses the heart's inability to pump sufficient blood by decreased blood perfusion (flow, pressure, etc.) in the renal arteries20 and other parts of the renovasculature. Therenal system10 responds to this to condition by initiating or contributing to a neurohormonal sequence that signals the heart to increase heart rate and force of contraction to increase the cardiac output, signals the kidneys to expand the blood volume by retaining sodium and water, and it signals the arterioles to constrict to elevate the blood pressure. The cardiac, renal and vascular responses increase the workload of the heart, further accelerating myocardial damage and exacerbating the heart failure state. To address this problem, the present invention basically provides a number of devices, systems and methods by which the renal system experiences normal or supranormal perfusion even in the face of reduced cardiac output and/or vasoconstriction. By maintaining or augmenting renal perfusion, therenal system10 including renal baroreceptors and the juxtaglomerular apparatus are not activated, and the viscous cycle referred to above may be stopped or at least moderated.
• In the case of end stage renal disease (ESRD), the kidney has often undergone substantial scarring and fibrosis. Thus, perfusion of the kidney and filtration of the blood are limited. The present invention provides a number of devices, systems and methods by which renal perfusion and pressure can be increased, thereby restoring or augmenting perfusion of the kidney and blood filtration. In addition, by increasing renal perfusion, the present invention increases interstitial pressure to reduce sodium and water reabsorption, which have been shown to be interrelated.
• With reference toFIGS. 25, the present invention generally provides a system including a physiologic sensor30 (e.g., a transducer or a gauge), a bloodperfusion modification device50,60,70 and/or80 (e.g., a flow regulator, a flow redirector or a pump), and acontrol system40. As used herein, perfusion, blood perfusion and renal perfusion generally refer to a fluid dynamic property of blood flow such as volumetric flow rate, flow velocity and/or pressure including absolute, mean or pulse pressure, or a fluid static property such as interstitial pressure. Thesensor30 senses and/or monitors one or more fluid dynamic properties of blood flow or renal pressure or function and is generically referred to herein as a sensor. Similarly, the bloodperfusion modification devices50,60,70,80 modify one or more fluid dynamic properties of blood flow and are generically referred to herein as modification devices. In each embodiment, the connections between thecomponents30/40/50/60/70/80 may be physical (e.g., wires, tubes, cables, etc.) or remote (e.g., transmitter/receiver, inductive, magnetic, etc.). For physical connections, the connection may travel intraarterially, intravenously, intraabdominally, subcutaneously, or through other natural tissue paths.
• The need to preserve or augment renal blood perfusion or pressure may be, for example, detected by thesensor30, which may be placed in one or both renal arteries20, the descendingaorta14, or upstream thereof, within the kidney itself or in the urinary bladder. Thecontrol system40 generates a control signal as a function of the received sensor signal. The control signal activates, deactivates or modifies one or more parameters of the bloodperfusion modification device50,60,70,80. Thus, when thesensor30 detects a reduction in cardiac output, thecontrol system40 generates an activation control signal to activate the bloodperfusion modification device50,60,70,80 thereby increasing renovascular perfusion such that therenal system10 does not experience reduced perfusion. When thesensor30 detects improvement or normalization in the sensed parameter, thecontrol system40 generates a control signal to deactivate or otherwise modify the activity of the bloodperfusion modification device50,60,70,80.
• With continued reference toFIGS. 25, thesensor30 is operably coupled to thecontrol system40 by electric sensor cable or lead32. Thesensor30 may comprise any suitable device that measures a fluid dynamic property of blood flow or other parameters) of interest which is (are) indicative of the need to modify (i.e., increase) renal perfusion. For example, thesensor30 may comprise a transducer or gauge that measures blood pressure (systolic, diastolic, pulse or average pressure), blood volumetric flow rate, blood flow velocity, etc. Alternatively, thesensor30 may comprise a transducer or gauge that measures urine production (e.g., volumetric), composition or concentration, a change in any of which may be indicative of the need to modify renal perfusion. Examples of suitable transducers or gauges for thesensor30 include a piezoelectric pressure transducer, an ultrasonic flow velocity transducer, an ultrasonic volumetric flow rate transducer, a thermodilution flow velocity transducer, and a capacitive pressure transducer. Although only onesensor30 is shown,multiple sensors30 of the same or different type at the same or different location may be utilized.
• In this embodiment, thesensor30 is preferably positioned on the arterial side of the renal vasculature. In particular, thesensor30 may be located in or on one or both kidneys12, renal arteries20, the descendingaorta14, or upstream thereof, such that suboptimal renal perfusion may be readily ascertained. The sensor may alternatively be implanted in the bladder to measure urine production. Thesensor30 may be mounted intravascularly or extravascularly, depending on the type of transducer or gauge utilized.
• With continued reference toFIGS. 25,control system40 includes acontrol block41 comprising aprocessor43 and amemory42.Control system40 is connected to thesensor30 by way ofsensor cable32.Control system40 is also connected to the bloodperfusion modification device50,60,70,80 by way ofelectric control cable38. Thus, thecontrol system40 receives a sensor signal (also referred to as a transducer signal) from thesensor30 by way ofsensor cable32, and transmits a control signal to the bloodperfusion modification device50,60,70,80 by way ofcontrol cable38.
• Thememory42 may contain data related to the sensor signal, the control signal, and/or values and commands provided by theinput device44. Thememory42 may also include software containing one or more algorithms defining one or more functions or relationships between the control signal and the sensor signal. The algorithm may dictate activation, deactivation or modification control signals depending on the sensor signal or a mathematical derivative thereof. For example, the algorithm may dictate an activation control signal when the sensor signal falls below a lower predetermined threshold value. The algorithm may also dictate a deactivation control signal when the sensor signal rises above an upper predetermined uphold threshold value.
• The following predetermined threshold values are provided by way of example, not limitation. If the sensor signal is indicative of systolic pressure, the lower threshold value may be approximately 80 mm Hg and the upper threshold value may be approximately 120 mm Hg. If the sensor signal is indicative of diastolic pressure, the lower threshold value may be approximately 60 mm Hg and the upper threshold value may be approximately 80 mm Hg. If the sensor signal is indicative of mean pressure, the lower threshold value may be approximately 70 mm Hg and the upper threshold value may be approximately 110 mm Hg. If the sensor signal is indicative of flow rate, the lower threshold value may be approximately 500 ml/min and the upper threshold value may be approximately 700 ml/min for each kidney. In essence, the algorithm dictates activation or deactivation of the bloodperfusion modification device50,60,70,80 to thereby increase or decrease real or apparent renovascular perfusion by instigating a control signal transmission as a function of the sensor signal.
• Thecontrol system40 may operate as a closed loop utilizing feedback from thesensor30, or as an open loop utilizing commands received byinput device44. The open loop operation of thecontrol system40 preferably utilizes some feedback from thesensor30, but may also operate without feedback. Commands received by theinput device44 may directly influence the control signal or may alter the software and related algorithms contained inmemory42. The patient and/or treating physician may provide commands to inputdevice44.Display45 may be used to view the sensor signal and/or the software contained inmemory42.
• The control signal generated by thecontrol system40 may be continuous, periodic, episodic or a combination thereof, as dictated by a preset or programmable algorithm contained inmemory42. Continuous control signals include a constant pulse, a constant sequence of pulses, a triggered pulse and a triggered sequence of pulses. Examples of periodic control signals include each of the continuous control signals described above which have a designated start time (e.g., beginning of each minute, hour or day) and a designated duration (e.g., 1 second, 1 minute, 1 hour). Examples of episodic control signals include each of the continuous control signals described above which are triggered by an episode (e.g., activation by the patient/physician, an increase in blood pressure above a certain threshold, ECG, etc).
• Thecontrol system40 may be implanted in whole or in part. For example, theentire control system40 may be carried externally by the patient utilizing transdermal connections to thesensor lead32 and thecontrol lead38. Alternatively, thecontrol block41 may be implanted with theinput device44 anddisplay45 carried externally by the patient utilizing transdermal connections therebetween. As a further alternative, the transdermal connections may be replaced by cooperating transmitters/receivers to remotely communicate between components of thecontrol system40 and/or thesensor30 and bloodperfusion modification device50,60,70,80. If all of the components are implanted, the inter component connections may be eliminated.
• Refer now toFIG. 2 which schematically illustrates a renalvein flow regulator50 in accordance with an embodiment of the present invention. Theflow regulator50 may be intravascularly or extravascularly positioned in or on one or both renal veins22 or downstream thereof on theinferior vena cava16.Flow regulator50 may be activated or deactivated by a control signal received fromcontrol cable38. When activated, theflow regulator50 constricts the renal vein22 or otherwise reduces the cross sectional area of the lumen therein to create back pressure in the renovasculature, thereby increasing blood and interstitial pressure in the renal tissues. By creating back pressure in the renal tissues during episodes of reduced renal perfusion, therenal system10 does not perceive the reduction in perfusion.
• Refer now toFIG. 3 which schematically illustrates aflow redirector60 in accordance with another embodiment of the present invention. Theflow redirector60 may be intravascularly or extravasculary positioned in or on the descendingaorta14 downstream of the renal arteries20, or in or on one or both of the common iliac arteries28. Theflow redirector60 may be activated or deactivated by a control signal received fromcontrol cable38. When activated, theflow redirector60 constricts the descending aorta or otherwise reduces the size of the lumen therein to redirect flow to the renal arteries20 thereby increasing renovascular perfusion. By artificially increasing renovascular perfusion during a state of reduced cardiac output, renal artery constriction or renal artery stenosis, renal perfusion is preserved or enhanced. Preferably, theflow redirector60 would be activated in such a manner as to minimize the effects on downstream perfusion into the lower extremities.
• Refer now toFIG. 4 which schematically illustrates an arterial blood flow pump70 in accordance with another embodiment of the present invention. Thearterial flow pump70 may be positioned intravascularly or extravascularly in or on the descendingaorta14 upstream of the renal arteries20 or in the renal arteries20. Thearterial flow pump70 may be activated and deactivated by a control signal received fromcontrol cable38. When activated, thearterial flow pump70 supplements arterial blood flow to the renal arteries20 thereby increasing renal perfusion.
• Refer now toFIG. 5 which schematically illustrates a venous blood flow pump80 in accordance with another embodiment of the present invention. Venous flow pump80 may be intravascularly or extravascularly may be positioned in or on the renal veins22, or in or on theinferior vena cava16 downstream of the renal veins22. Thevenous flow pump80 may be activated and deactivated by a control signal received fromcontrol cable38. When activated, thevenous flow pump80 reduces blood flow or causes back flow in the renal veins22 thereby increasing renal back pressure.
• Refer now toFIGS. 612 which illustrate various embodiments of flow regulators, flow redirectors and pumps that may be utilized for the blood perfusion tomodification devices50,60,70,80 described with reference toFIGS. 25. Each ofFIGS. 612 schematically illustrate intravascular or extravascular devices disposed in or on ageneric vessel90 having avascular wall92 and avascular lumen94. Thevessel90 generically refers to the portion of the vasculature in or on which the bloodperfusion modification device50,60,70,80 is positioned as described previously. Each of the illustrations ofFIGS. 612 are longitudinal cross sectional views unless otherwise specified and are generally circular in lateral cross section unless otherwise specified.
• Refer now specifically toFIGS. 6A and 6B which show side cross sectional schematic illustrations of an externalinflatable cuff100 in accordance with an embodiment of the present invention.FIG. 6A illustrates theinflatable cuff100 in the deactivated (unconstricted) state, andFIG. 6B illustrates theinflatable cuff100 in the activated (constricted) state. Theinflatable cuff100 may be used for the renalvein flow regulator50 illustrated inFIG. 2 or theflow redirector60 illustrated inFIG. 3. Those skilled in the art will recognize theinflatable cuff100 illustrated is merely schematic and is intended to generically refer to a wide variety of inflatable cuffs. Examples of inflatable cuffs that may be adapted for use in the present invention are disclosed in U.S. Pat. No. 4,256,094 to Kapp et al. and U.S. Pat. No. 4,881,939 to Newman, the entire disclosures of which are hereby incorporated by reference.
• Inflatable cuff100 includes ahousing102 which may be connected to thevessel wall92 utilizing conventional techniques such assutures104.Housing102 contains an inflatableannular balloon106 having an interior107 which is in fluid communication with afluid line108. Theballoon106 may be an annular geometry with a central passageway to accommodate thevessel90 therein as illustrated, or may be a geometry without a passageway and reside on one side of thevessel90. In addition, oneballoon106 may be utilized as shown, or a plurality ofballoons106 may be utilized.
• A pressure/vacuum source110 (e.g., a closed volume piston pump) selectively inflates and deflates theballoon106 by way ofpressure line108. The pressure/vacuum source110 is preferably implanted, but may be carried externally by the patient with a transdermal connection to thepressure line108. A saline liquid inflation fluid is preferred, but other fluids (i.e. liquids and gases) may be used.
• The pressure/vacuum source110 is connected to thecontrol cable38, which provides a control signal fromcontrol system40 to activate or deactivate the pressure/vacuum source110 and thereby inflate or deflate theballoon106. When activated, the pressure/vacuum source110 applies pressure and causes theballoon106 to inflate thereby constricting thevascular wall92 and obstructing or reducing the size of theinternal lumen94. Theinternal lumen94 may be partially or totally occluded by controlling the degree ofballoon106 inflation. When deactivated, the pressure/vacuum source110 applies vacuum and causes theballoon106 to deflate thereby permitting thevascular wall92 to return to its unconstricted state and restoring the nominal size of theinternal lumen94.
• The pressure/vacuum source110 may be automatically actuated by thecontrol system40 as discussed above, or may be manually actuated. An example of an externally manually actuated pressure/vacuum source is disclosed in U.S. Pat. No. 4,709,690 to Haber, the entire disclosure of which is hereby incorporated by reference. Examples of transdermally manually actuated pressure/vacuum sources are disclosed in U.S. Pat. No. 4,586,501 to Claracq, U.S. Pat. No. 4,828,544 to Lane et al., and U.S. Pat. No. 5,634,878 to Grundei et al., the entire disclosures of which are hereby incorporated by reference.
• In use, thesensor30 detects a reduction in renal perfusion or other change indicative of the need to activate the system as indicated by a sensor signal transmitted by way ofsensor cable32 to thecontrol system40. In response, thecontrol system40 transmits a control signal as a function the sensor signal as dictated by the algorithm contained inmemory42. The control signal is transmitted by way ofcontrol cable38 to the pressure/vacuum source110. Depending on the control signal, the pressurizedfluid source110 is activated (pressure) or deactivated (vacuum) to inflate or deflate theballoon106.
• If theinflatable cuff100 is utilized as a renalvein flow regulator50 as illustrated inFIG. 2, the reduced size of thevascular lumen94 causes back pressure in the renal veins22 and ultimately the renal parenchyma and arterial circulation thereby causing an apparent increase in renovascular perfusion and pressure. If theinflatable cuff100 is utilized as aflow redirector60 as illustrated inFIG. 3, the reduced size of thevascular lumen94 causes blood to be redirected into the renal arteries20 thereby causing an increase in renovascular perfusion. In either instance, renovascular perfusion and/or intrarenal pressure are maintained or augmented.
• Inflatable cuff100 is one example of many different mechanisms for applying external compression to thevascular wall92 to reduce the size of theinternal lumen94. Other mechanisms for applying for external compression to thevascular wall92 are described in greater detail with reference toFIGS. 8A,8B,9A and9B. In addition to the specific mechanisms mentioned herein, those skilled in the art will recognize that to many other mechanisms may be adapted for this application. For example, external compression may be applied utilizing an electromagnetically actuated ferro fluid device as disclosed in the U.S. Pat. No. 5,509,888 to Miller, the entire disclosure of which is hereby incorporated by reference. Another example of an electromagnetically actuated ferro fluid type external compression device is disclosed in U.S. Pat. No. 4,053,952 to Goldstein, the entire disclosure of which is incorporated by reference.
• Refer now toFIGS. 7A and 7B which show cross sectional schematic illustrations of an internalinflatable balloon device200 in accordance with another embodiment of the present invention.FIG. 7A illustrates theinflatable balloon device200 in the deactivated (unconstricted) state, andFIG. 7B illustrates theinflatable balloon device200 in the activated (constricted) state. Theinflatable balloon device200 may be used for the renalvein flow regulator50 illustrated inFIG. 2 or theflow redirector60 illustrated inFIG. 3.
• Those skilled in the art will recognize that the internalinflatable balloon device200 is merely schematic and is intended to generically refer to a wide variety of internal occlusion devices. An example of an internal inflatable balloon device that may be adapted for use in the present invention is disclosed in U.S. Pat. No. 4,682,583 to Burton et al., the entire disclosure of which is hereby incorporated by reference. Another example of an internal inflatable balloon device that may be adapted for use in the present invention is disclosed in U.S. Pat. No. 5,634,878 to Grundei et al., the entire disclosure of which is hereby incorporated by reference.
• Inflatable balloon device200 includes ahousing202 which may be connected to the inside surface of thevessel wall92 utilizing conventional techniques such as those used for implanting vascular stents, grafts and filters.Housing202 includes an inflatableannular balloon206 having an interior207 which is in fluid communication with afluid line208. Theballoon206 may be an annular geometry with a central perfusion passageway as illustrated, or may be a geometry without a passageway and reside on one side of thevessel90. In addition, oneballoon206 may be utilized as shown, or a plurality ofballoons206 may be used.
• A pressure/vacuum source110 selectively inflates and deflates theballoon206 by way ofpressure line208. The pressure/vacuum source110 is connected to thecontrol cable38, which provides a control signal fromcontrol system40 to activate or deactivate the pressure/vacuum source110 and thereby inflate or deflate theballoon206. When activated, the pressure/vacuum source110 applies pressure and causes theballoon206 to inflate thereby obstructing or reducing the size of theinternal lumen94. Theinternal lumen94 may be partially or totally occluded by adjusting the degree ofballoon206 inflation. When deactivated, the pressure/vacuum source110 applies vacuum and causes theballoon206 to deflate thereby restoring the nominal size of theinternal lumen94. The internalinflatable balloon device200 basically operates on the same principles as theexternal compression device100 described previously, except thatinflatable balloon device200 does not utilize external compression, but rather totally or partially occludes thevascular lumen94 without affecting thevascular wall92.
• Refer now toFIGS. 8A and 8B which show side cross sectional schematic illustrations of apiston device300 in accordance with another embodiment of the present invention.FIG. 8A illustrates thepiston device300 in the deactivated (unconstricted) state, andFIG. 8B illustrates thepiston device300 in the activated (constricted) state. Thepiston device300 may be used for the renalvein flow regulator50 illustrated inFIG. 2 or theflow redirector60 illustrated inFIG. 3. Those skilled in the art will recognize that thepiston device300 illustrated is merely schematic and is intended to generically refer to a wide variety of piston type devices. An example of a piston type device that may be adapted for use in the present invention is disclosed in U.S. Pat. No. 4,014,318 to Dockum et al., the entire disclosure of which is hereby incorporated by reference.
• Piston device300 includes ahousing302 which may be connected to thevessel wall92 utilizing conventional techniques such assutures304.Housing302 includes aninternal chamber307 in whichpiston306 is slidably disposed. Theinternal chamber307 is in fluid communication with afluid line308. A pressure/vacuum source110 selectively fills an empties thechamber307 by way ofpressure line308. The pressure/vacuum source110 is connected to thecontrol cable38, which provides a control signal fromcontrol system40 to activate or deactivate the pressure/vacuum source110.
• When activated, the pressure/vacuum source110 fills theinternal chamber307 with fluid thereby displacing thepiston306 to constrict thevascular wall92 and reduce the size of theinternal lumen94. Theinternal lumen94 may be partially or totally occluded by adjusting the displacement distance of thepiston306. When deactivated, the pressure/vacuum source110 empties theinternal chamber307 causing thepiston306 to be displaced back into thechamber307 thereby permitting thevascular wall92 to return to its unconstricted state and restoring the nominal size of theinternal lumen94. The function and use of thepiston device300 is otherwise essentially the same as the otherexternal compression device100 discussed previously.
• As illustrated and described, thepiston device300 operates by hydraulic actuation. Alternatively, thepiston device300 may operate by electromagnetic actuation such as provided by a solenoid device. An example of an electromagnetic solenoid device is disclosed in Dockum et al. '318 mentioned previously. If electromagnetic actuation is utilized, the pressure/vacuum source110 may be replaced by a suitable amplifier to power the electromagnets in the solenoid. The function and use of the solenoid alternative is otherwise essentially the same as the hydraulic embodiment discussed above.
• Refer now toFIGS. 9A and 9B which show side cross sectional schematic illustrations of arotatable ring device400 in accordance with another embodiment of the present invention.FIG. 9A illustrates therotatable ring device400 in the deactivated (unconstricted) state andFIG. 9B illustrates therotatable ring device400 in the activated (constricted) state. Therotatable ring device400 may be used for the renalvein flow regulator50 illustrated inFIG. 2 or theflow redirector60 illustrated inFIG. 3. Those skilled in the art will recognize that therotatable ring device400 is merely schematic and is intended to generically refer to a wide variety of rotatable ring devices. An example of a rotatable ring device that may be adapted for use in the present invention is disclosed in U.S. Pat. No. 4,551,862 to Haber, the entire disclosure of which is hereby incorporated by reference.
• Rotatable ring device400 includes ahousing402 which may be connected to thevessel wall92 utilizing conventional techniques such assutures404.Housing402 includes one ormore rings406 which are operably connected to alinear actuation cable408 to cause rotation of the ring or rings406 substantially as described in Haber '862. Thelinear actuation cable408 is connected to asolenoid device410 which selectively pushes or pulls thelinear actuation cable408 to cause clockwise or counter clockwise rotation of the rotatable rings406.
• Thesolenoid device410 is connected to thecontrol cable38 which provides a control signal from thecontrol system40 to activate or deactivate thesolenoid device410 and thereby rotate therings406. When activated, thesolenoid410 causes the rotatable rings406 to constrict thevascular wall92 and reduce the size of thelumen94. Theinternal lumen94 may be partially or totally occluded by adjusting the degree of rotation of therings406. When deactivated, thesolenoid device410 causes the rotatable rings to unconstrict thereby permitting thevascular wall92 to return to its unconstricted state and restoring the nominal size of theinternal lumen94. The function and use of therotatable ring device400 is otherwise substantially the same as the otherexternal compression devices100,300 discussed previously.
• Refer now toFIG. 10 which shows a side cross sectional schematic illustration of anexternal pump500 in accordance with an embodiment of the present invention.FIG. 10 illustrates thepump500 in the deactivated state. Theexternal pump500 may be used for thearterial flow pump70 illustrated inFIG. 4 or thevenous flow pump80 inFIG. 5. Those skilled in the art will recognize that theexternal pump500 is merely schematic and is intended to generically refer to a wide variety of extraluminal vascular pumps. An example of an extraluminal vascular pump that may be adapted for use in the present invention is disclosed in Dockum et al. '318 mentioned previously.
• Extraluminal pump500 includes ahousing502 which may be connected to thevessel wall92 utilizing conventional techniques such assutures504.Housing502 includes a plurality ofinflatable balloons506 each having an interior507 which is in fluid communication with a plurality offluid lines508. Fluid communication to each of theballoons506 is maintained by separate lumens within thefluid line508 such that theballoons506 may be inflated independently.
• A pressure/vacuum source110 is fluidly connected to a manifold510 which sequentially inflates and deflates each of theballoons506 to cause a sequence of constrictions about thevessel wall92, thereby creating a pumping action within thevascular lumen94. The direction and speed of the inflation sequence may be modified to change the pumping direction and flow rate. The pressure/vacuum source110 is connected to thecontrol cable38 which provides a control signal from thecontrol system40 to activate and deactivate the pressure/vacuum source110 andmanifold510. When activated, the pressure/vacuum source110 and manifold510 cause theballoons506 to sequentially inflate thereby producing the pumping action. After theballoons506 have been sequentially inflated, the pressure/vacuum source110 applies a vacuum to deflate theballoons506. The pressure/vacuum source110 andmanifold510 may be reactivated to initiate another pumping cycle. If no further pumping action is desired, the pressure/vacuum source110 maintains a vacuum such that theballoons506 remain deflated.
• If theexternal pump500 is used for thearterial flow pump70 illustrated inFIG. 4, theexternal pump500 selectively supplements arterial blood flow and/or perfusion pressure to therenal arteries200 thereby increasing renal perfusion. If theexternal pump500 is utilized for thevenous flow pump80 illustrated inFIG. 5, theexternal pump500 reduces blood flow or causes back flow in the renal veins22 thereby increasing renal back pressure. In either instance, the renovascular perfusion and/or intrarenal pressure are maintained or augmented.
• Theexternal pump500 may utilize hydraulically actuatedballoons506 as illustrated and described, or may utilize hydraulically actuated pistons similar to the embodiment described with reference toFIGS. 8A and 8B. Alternatively, the pistons may be electromagnetically actuated as with a solenoid type device as described in Dockum et al. '318 and as described with reference to the alternative embodiment ofFIGS. 8A and 8B. Thus, theexternal pump500 may be hydraulically actuated by utilizingballoons506, or may be hydraulically or electromagnetically actuated by replacing theballoons506 with pistons slidably disposed in chambers.
• Refer now toFIG. 11 which shows a side cross sectional schematic illustration of aninternal pump600 in accordance with an embodiment of the present invention.FIG. 11 illustrates theintraluminal pump600 in the static or deactivated state. Theintraluminal pump600 may be utilized for thearterial flow pump70 illustrated inFIG. 4 or thevenous flow pump80 illustrated inFIG. 5. Those skilled in the art will recognize that theintraluminal pump600 is merely schematic and is intended to generically wide variety of intraluminal vascular pumps. An example of an intraluminal vascular pump suitable for use in the present invention is disclosed in U.S. Pat. No. 5,692,882 to Bozeman, Jr. et al., the entire disclosure of which is hereby incorporated by reference.
• Theintraluminal pump600 includes ahousing602 which may be connected to thevessel wall92 utilizing the same anchoring techniques used by intravascular stents, to grafts and filters.Housing602 includes proximal anddistal struts603 which supportrotatable axle604. One ormore impeller blades605 are rigidly connected to theaxle604 and rotate relative to thehousing602 and struts603. When theimpeller blades605 are rotated, blood in thevascular lumen94 is biased in the proximal or distal direction.Impeller blades605 may be formed of a ferrous material suitable for forming into permanent magnets. Alternatively, theimpeller blades605 may be formed of a nonferrous material but include a ferrous material disposed thereon for forming into permanent magnets.
• Thehousing602 includes a plurality ofelectrical windings606 which may be selectively activated byelectrical cable608.Electrical cable608 is connected topower amplifier610 which may be selectively activated or deactivated by thecontrol system40 by way ofcontrol cable38. By activating thepower amplifier610, electrical power is supplied to thecoil windings606 in thehousing602. Thecoil windings606 generate a magnetic field causing the permanent magnets disposed on theimpeller blade605 to be displaced.Multiple coil windings606 may be utilized about the periphery of thehousing602 to sequentially activate and deactivate magnetic fields causing rotation of theimpeller blades605. The direction and frequency of the sequential activation may be modified to change the direction and speed of rotation, and thus the direction and degree of pumping action. As an alternative, supplemental fluid may be supplied to thepump600 by connection to a source of blood within the body or by connection to a fluid reservoir containing a suitable fluid such as saline. The function and use ofinternal pump600 is otherwise essentially the same asexternal pump500.
• Refer now toFIG. 12 which shows a side cross sectional schematic illustration of adrug delivery device700 in accordance with an embodiment of the present invention. Those skilled in the art will recognize that other site specific drug delivery devices may be utilized in place of thedelivery device700 illustrated.Delivery device700 includes ahousing702 which may be connected thevessel wall92 utilizing conventional techniques such assutures705.Housing702 includes anannular recess705 which is in fluid communication with afluid delivery line708.Annular recess705 is open to the exterior of thevascular wall92.Housing702 includesannular seals706 disposed proximally and distally of theannular recess705 to create a fluid tight seal between thehousing702 and thevascular wall92. By creating a fluid tight seal, theannular seals706 maintain fluid in theannular recess705. With this arrangement, fluid delivered to theannular recess705 viafluid delivery lines708 remains in intimate contact with the exterior of thevascular wall92 at the desired location.
• Fluid line708 is connected to a fluid delivery pump/reservoir710 which is connected to thecontrol cable38. Thecontrol cable38 provides a control signal from thecontrol system40 to activate or deactivate the pump/reservoir710. By selectively activating the pump/reservoir710, fluid contained in thereservoir710 is delivered to theannular recess705 by way offluid line708. The fluid contained in thereservoir710 is preferably a vasoconstrictor such as phenylephrine. Alternatively or in addition, the reservoir may contain a vasodilator such as hydralazine or nitroprusside.
• Accordingly, when the pump/reservoir710 is activated, the vasoconstrictor is delivered to theannular recess705 thereby constricting thevascular wall92 and obstructing or reducing the size of theinternal lumen94.Internal lumen94 may be partially or totally closed by varying the amount and strength of the vasoconstrictor. When deactivated, the pump/reservoir710 may deliver a dilution fluid or a vasodilator to reduce or reverse the effects of the vasoconstrictor, thereby permitting or causing thevascular wall92 to return to its unconstricted state and restoring the nominal size of theinternal lumen94. The function and use of thevasoconstrictor delivery device700 is otherwise substantially the same as theexternal compression devices100,300 described previously.
• From the foregoing, it should be apparent to those skilled in the art that the present invention provides a number ofdevices100,200,300,400,500,600,700 andsystems30,40,50,60,70,80 and methods by which the real or apparent renovasculature perfusion and intrarenal pressure may be selectively and controllably increased. By selectively and controllably increasing renovascular perfusion and interstitial hydrostatic pressure when the heart is unable to pump sufficient blood or when renal perfusion is suboptimal, the present invention reduces or reverses neurohormonal activation and fluid retention, and thereby minimizes their deleterious effects on the heart, vasculature, kidneys and other body systems.
• Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.

Claims (38)

1. A method of treating a patient comprising the steps of:

providing a blood perfusion modification device, wherein the modification device comprises a flow redirector, and wherein the flow redirector is positioned downstream of a renal artery to redirect blood flow to the renal artery;

positioning the blood perfusion modification device in the patient's renovascular circulation or immediately adjacent thereto; and

activating, deactivating or otherwise modifying the blood perfusion modification device to cause an increase in renal perfusion.

2. A method as inclaim 1, wherein the flow redirector is positioned in a descending aorta downstream of the renal artery to redirect blood flow to the renal artery.

3. A method as inclaim 1, wherein the flow redirector is positioned in a common iliac artery downstream of the renal artery to redirect blood flow to the renal artery.

4. A method as inclaim 1, wherein the modification device comprises a pump, and wherein the pump is positioned upstream of a renal artery to supplement blood flow therein.

5. A method as inclaim 1, wherein the modification device comprises a pump, and wherein the pump is positioned downstream of a renal vein to reduce blood flow or causes back flow therein.

6. A method as inclaim 1, wherein the modification device comprises a drug delivery device, and wherein the drug delivery device is positioned patient's renovascular circulation or immediately adjacent thereto.

7. A method as inclaim 1, wherein the modification device is positioned intravascularly.

8. A method as inclaim 1, wherein the modification device is positioned extravascularly.

9. A system for treating a patient, the system comprising:

a blood perfusion modification device positioned in the patient's renovascular circulation or immediately adjacent thereto;

a sensor dimensioned and configured to be positioned upstream of the blood perfusion modification device and upstream of the kidney of the patient to generate a signal indicative of a need to modify renal perfusion; and

a control system operably connected to the sensor and blood perfusion modification device, wherein the control system generates a control signal to activate, deactivate or otherwise modify the blood perfusion modification device as a function of the sensor signal to cause an increase in renal perfusion.

10-16. (canceled)

17. A system as inclaim 9, wherein the modification device comprises a flow redirector dimensioned and configured to be positioned downstream of a renal artery to redirect blood flow to the renal artery.

18. A system as inclaim 17, wherein the flow redirector is dimensioned and configured to be positioned extravascularly.

19. A system as inclaim 18, wherein the flow redirector comprises an inflatable cuff.

20. A system as inclaim 18, wherein the flow redirector comprises a rotatable ring.

21. A system as inclaim 18, wherein the flow redirector comprises a piston.

22. A system as inclaim 17, wherein the flow redirector is dimensioned and configured to be positioned intravascularly.

23. A system as inclaim 22, wherein the flow redirector comprises an inflatable balloon.

24. A system as inclaim 9, wherein the modification device comprises a pump positioned upstream of a renal artery to supplement blood flow therein.

25. A system as inclaim 9, wherein the modification device comprises a pump positioned downstream of a renal vein to reduce blood flow or causes back flow therein.

26. A system as inclaim 9, wherein the modification device comprises a drug delivery device dimensioned and configured to be positioned in or on the patient's renovascular circulation.

27. A system as inclaim 9, wherein the control system includes a processor and a memory.

28. A system as inclaim 27, wherein the memory includes software containing an algorithm defining a relationship between the control signal and the sensor signal.

29. A system as inclaim 28, wherein the algorithm dictates an activation, deactivation or modification control signal when the sensor signal falls below or rises above a predetermined threshold value.

30. A method for treating a patient comprising:

implanting a blood perfusion modification device in the renovascular circulation of a patient or immediately adjacent thereto;

activating, deactivating or otherwise modifying the blood perfusion modification device to cause an increase in renal perfusion; and

wherein the modification device comprises a flow redirector, and wherein the flow redirector is positioned downstream of a renal artery to redirect blood flow to the renal artery.

31. A method as inclaim 30, wherein the flow redirector is positioned in a descending aorta downstream of the renal artery to redirect blood flow to the renal artery.

32. A method as inclaim 30, wherein the flow redirector is positioned in a common iliac artery downstream of the renal artery to redirect blood flow to the renal artery.

33. A method as inclaim 30, wherein the modification device comprises a pump, and wherein the pump is positioned upstream of a renal artery to supplement blood flow therein.

34. A method as inclaim 30, wherein the modification device comprises a pump, and wherein the pump is positioned downstream of a renal vein to reduce blood flow or causes back flow therein.

35. A method as inclaim 30, wherein the modification device comprises a drug delivery device, and wherein the drug delivery device is positioned in patient's renovascular circulation or immediately adjacent thereto.

36. A method as inclaim 30, wherein the modification device is positioned intravascularly.

37. A method as inclaim 30, wherein the modification device is positioned extravascularly.

38. A method of treating renal disorders or hypertension, comprising:

implanting a first renal modulation device that contributes to renal function of a first kidney of a patient;

implanting a second renal modulation device that contributes to renal function of a second kidney of the patient; and

activating and/or deactivating the first renal modulation device and/or the second renal modulation device so to achieve bilateral renal neurohormonal modulation.

39. A method for selectively and controllably increasing renal perfusion, comprising:

positioning a renal modulation device proximate the renal vasculature;

providing a means for sensing cardiac output and/or renal perfusion; and

activating and/or deactivating the renal modulation device during periods of decreased cardiac output or suboptimal renal perfusion, so as to reduce or reverse neurohormonal activation and/or fluid retention.

40. A method, comprising:

implanting a renal modulation device adjacent to an elongated biological structure associated with renal function proximate a kidney of the patient, wherein the renal modulation device includes a cuff placed around a renal blood vessel of the kidney; and

causing the renal modulation device to be activated so as to at least partially block the renal vessel.

41. A method of treating renal disorders or hypertension, comprising:

providing a first renal modulation device that contributes to renal function of a first kidney of a patient;

providing a second renal modulation device that contributes to renal function of a second kidney of the patient; and

providing instructions, including:

implanting the first renal modulation device proximate a biological structure associated with renal function;

implanting the second renal modulation device proximate a biological structure associated with renal function;

activating and/or deactivating the first renal modulation device and/or the second renal modulation device so to achieve bilateral renal neurohormonal modulation.

42. A method for selectively and controllably increasing renal perfusion, comprising:

providing a renal modulation device;

providing a means for sensing cardiac output and/or renal perfusion;

providing instructions, including:

positioning a renal modulation device proximate the renal vasculature;

activating and/or deactivating the renal modulation device during periods of decreased cardiac output or suboptimal renal perfusion, so as to reduce or reverse neurohormonal activation and/or fluid retention.

43. A method, comprising:

providing a renal modulation device, including a cuff;

providing instructions, including:

implanting the renal modulation device adjacent to an elongated biological structure associated with renal function proximate a kidney of the patient, such that the cuff placed around a renal blood vessel of the kidney; and

activating the renal modulation device so as to at least partially block the renal vessel.

44. An apparatus, comprising:

a renal modulation device configured for placement proximate the renal vasculature; and

a controller configured to operate based on instructions to control activation of renal baroreceptors with the renal modulation device.

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