Cardiac stimulating apparatus having a blood clot filter and atrial pacer
An apparatus is provided for reducing the formation and migration of blood clots from an atrial appendage, such as the left atrial appendage, to the blood vessel system of a patient. The apparatus comprises an atrial pacer to treat non-rheumatic atrial fibrillation (NRAF) of an atrial appendage so that the formation blood clots within the atrial appendage is decreased or eliminated. In addition, the apparatus includes a blood clot filter supported by the atrial pacer proximate the atrial appendage and the atrium to reduce the migration of blood clots from the atrial appendage into the blood vessel system of a patient.
This is a continuation application of U.S. application Ser. No. 10/163,021, filed Jun. 4, 2002, which in turn claims the benefit of priority of U.S. Provisional Application No. 60/295,683, filed on Jun. 4, 2001, the entire contents of which application(s) are incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention relates generally to a device that deters migration of emboli from an atrial appendage into the vascular system of a patient, and more particularly to a device that includes a filter to deter such migration and a pacer to deter the formation of emboli such as blood clots within the atrial appendage.
BACKGROUND OF THE INVENTIONNon-rheumatic atrial fibrillation (NRAF) is associated with thromboembolic complications such as strokes. For example, when a thrombus or embolus occludes a vessel supplying blood to the brain, a stroke may result causing temporary or lasting paralysis of a part of the body or, in severe cases, death. Blockage of other blood vessels can occur as well causing attendant health concerns, including heart attack or gangrene. Presently, a five percent risk of stroke per year in a largely aging population causes NRAF to be a significant health concern. Given the potentially irreversible and destructive nature of such blood vessel occlusion, safe and effective methods are needed to eliminate embolic material like blood clots from the vascular system, some of which may be formed within an atrial appendage of the heart.
The left atrial appendage forms a small protrusion which is attached to the lateral wall of the left atrium between the mitral valve and the root of the left pulmonary vein and normally contracts along with the left atrium. Atrial fibrillation is a cardiac condition wherein the atria beat faster than the ventricles, causing the ventricles to contract irregularly and consequently eject less blood into the vascular system. A major problem associated with atrial fibrillation is pooling of blood in the left atrial appendage.
During NRAF the left atrial appendage may not fully contract, leaving stagnant blood within the left atrial appendage. In turn, the stagnant blood may create a condition favorable to the formation of blood clots within the left atrial appendage. Such clots may travel from the left atrial appendage into the left atrium and into the vascular system, thereby increasing the danger of stroke or cardiac blockage.
Traditional treatments to mitigate the risks posed by blood clots include the use of anticoagulants to dissolve the clots. For example, recently published results from stroke prevention trials suggest that prophylaxis with anticoagulation is beneficial to patients with non-rheumatic, non-valvular atrial fibrillation. Current therapeutic interventions include anticoagulation with coumedin. In addition, therapeutic interventions include the use of atrial rate regulating medications. However, both of these treatment approaches pose potential complications such as internal bleeding, as well as other negative side effects caused by the rate regulating therapeutic agents.
In addition to pharmacological treatments, complex radical surgical methods are available to treat atrial fibrillation. Such treatments include, for example, atrial incisions or removal of the left atrial appendage, which have been attempted in a limited, experimental way. Such approaches are highly invasive and pose a risk of mortality to the patient. Thus, a pressing need exists for means by which the formation of blood clots the left atrial appendage is substantially deterred while preventing the migration of any blood clots which may form from entering the vascular system.
U.S. Pat. No. 6,152,144 to Lesh et al., for example, discloses a device and method for obliterating or occluding a body cavity or passageway. Specifically, the patent to Lesh is directed to a device and method for obliterating or occluding the left atrial appendage of a patient's heart. In one embodiment, Lesh et al. disclose a frame structure having a barrier or mesh material disposed over it to act as a barrier to the passage of embolic material.
However, Lesh et al. do not disclose a device or method suited to treat atrial fibrillation, or other arrhythmias of the heart, to thereby prevent the formation of clots in the left atrial appendage. As such, the barrier embodiment of Lesh et al. permits ongoing formation of clots within the left atrial appendage, which may eventually occlude the barrier material to prevent fluid flow as well as embolic material flow through the occluded barrier. Such a situation may present a health concern as the left atrial appendage contracts and the blood enclosed therein is unable to exit the left atrial appendage. Such contraction may result in an increased pressure in the left atrial appendage capable of weakening the wall of the left atrial appendage. Additionally, as the barrier embodiment of Lesh et al. does not prevent the formation of clots, it is possible that the volume of the left atrial appendage may eventually be filled with coagulated blood. Thus, filtering alone poses possible added health concerns.
Regarding the treatment of atrial fibrillation, it is known to use a pacemaker, for example, as disclosed in U.S. Pat. No. 6,178,351 B1 to Mower. Mower discloses a pacemaker that is capable of pacing the atria from multiple sites, but does not address prevention of migration of embolic material within the vascular system. Moreover, neither Mower nor Lesh suggests combining a pacer with an embolic barrier for use in the heart.
Accordingly, there is a need for an apparatus for mitigating the risks associated with emboli originating in the left atrial appendage and also for reducing the tendency of such emboli, such as blood clots, to form therein.
SUMMARY OF THE INVENTIONAn apparatus is provided for deterring the formation and migration of blood clots from an atrial appendage, such as a left or right atrial appendage, into the blood vessel system, i.e. vascular system, of a patient. In particular, an apparatus of the present invention comprises an atrial pacer to treat non-rheumatic atrial fibrillation (NRAF) or other arrhythmias of an atrial appendage so that the formation of blood clots within such atrial appendage is decreased or eliminated. In addition, the apparatus provides a blood clot filter to deter the migration of blood clots from an atrial appendage into the blood vessel system of a patient.
More specifically, the apparatus comprises a filter for reducing the transport of emboli from an atrial appendage to an atrium of the heart. The filter is formed to provide a structure suitable for separating blood clots from the blood and for reducing passage of blood clots from the atrial appendage into the atrium and general circulation. In accordance with one aspect of the invention, the filter can take the form of a plurality of spokes extending outwardly from the atrial pacer. In another aspect, the filter can take the form of a mesh having pores sized to deter the passage of blood clots.
In accordance with another aspect of the invention, the apparatus comprises an atrial pacer which supports the filter between an atrial appendage and the atrium. The atrial pacer is adapted to be in contact with a wall of the atrial appendage so the atrial pacer may detect and reduce atrial fibrillation in the atrial appendage. The pacer also includes a sensor which may form an integral part of the atrial pacer for sensing fibrillation in the atrial appendage. In an alternative arrangement, the sensor may be adapted to be positioned externally to the heart. In this external arrangement, a lead wire may be provided between the sensor and the atrial wall, to provide sensing contact between the sensor and the atrial wall. The atrial pacer also comprises a stimulator for stimulating the atrial appendage. The simulator may take the form of an electrode for making electrical contact with the wall of the atrial appendage to apply stimulating signals to the atrial appendage. The stimulator may be activated in response to a signal from the sensor indicating the presence of NRAF, or other arrythmias, in the atrial appendage.
A control unit adapted to be positioned externally to the heart may optionally be provided for controlling the atrial pacer. The control unit may communicate with the sensor and/or the stimulator using a lead wire or wireless technology. In addition, the sensor may be disposed within the control unit. For example, in the arrangement where the sensor is positioned externally to the heart, the sensor may be incorporated within the control unit.
BRIEF DESCRIPTION OF THE DRAWINGSThe foregoing summary and the following detailed description of the preferred embodiments of the present invention will be best understood when read in conjunction with the appended drawings, in which:
A cardiac stimulating apparatus 10, 100 is provided for substantially reducing the formation of blood clots in an atrial appendage of a heart, such as the left atrial appendage 210, and reducing the migration of such clots into the blood vessel system of a patient. The apparatus 10, 100 comprises a filtration device 28, 124 to reduce migration of embolic material, such as blood clots or the like. In addition, the apparatus 10, 100 includes an atrial pacer 12, 112 to treat arrythmias, such as non-rheumatic atrial fibrillation (NRAF), of the left atrial appendage 210 to deter the formation blood clots within the left atrial appendage 210.
Turning now to
Extending outwardly from the elongated generally tubular body 14, a filtration device is provided to deter the migration of blood clots from the left atrial appendage 210 into the left atrium 200 of the heart. As shown in
The mesh-like material of the filter 28 may be formed from a metal, such as a stainless-steel, for example. Alternatively, the filter 28 may be formed from a polymeric material, such as a Nylon or Dacron mesh. Other suitable materials such as PTFE or polyamides may also be used. In particular, it is preferable that the filter 28 be formed of a resilient material capable of being collapsed about the body 14 of the atrial pacer 12, as shown in
The wider end of the filter 28 includes a rim portion 20 which defines the base of the filter 28. The rim portion 20 is sized to circumscribe the opening between the left atrial appendage 210 and left atrium 200, so that emplacement the cardiac stimulating device 10 in the left atrial appendage 210 generally positions the rim portion 20 near the opening left atrial appendage 210 so as to form and maintain a seal therewith. To effect and maintain such a seal, the rim portion 20 may be formed of or covered by a soft polymer material. The rim portion 20 may have a transverse dimension of about 2 to 40 mm, preferably about 25 to 35 mm. The transverse dimension of the rim portion 20 should be selected with regard to the size of the left atrial appendage opening, which may vary among patients, especially those patients having heart disease related conditions.
The rim portion 20 may also include a plurality of holes through which sutures may be placed to anchor the rim portion 20 proximate to the opening of the left atrial appendage 210. Alternatively or additionally, the rim portion 20 may have a spring-like action which causes the rim portion 20 to expand generally radially outward from the longitudinal axis of the atrial pacer 12, so that the rim portion 20 applies pressure against a region proximate the opening of the left atrial appendage 210 to form a seal proximate the opening of the left atrial appendage 210. For example, the rim portion 20 may be formed of a shape memory metal, such as NiTi, having a memorized shape larger than that of the opening of the left atrial appendage 210 to supply the radially outward pressure on the opening. The filter 28 is attached to the atrial pacer 12 at such a location so as to permit the rim portion 20 to substantially form a seal within the left atrial appendage opening and to permit the first end 18 of the atrial pacer 12 to contact the wall of the atrial appendage 210.
Referring now to
The spokes 124 each comprise a first end 125 attached to the elongated body 114 of the atrial pacer 112 and a second end 127 of the spokes 124 for engaging a region of the heart in the vicinity of the left atrial appendage 210. The second end 127 of the spokes 124 may terminate in a hook-like tine 126 formed to anchor the spokes 124 and retain the atrial pacer 112 within the left atrial appendage 210. In addition, all or some of the second ends 127 of the spokes 124 may include a hole suitable for placing a suture therethrough for attachment to the left atrial appendage 210. The number of spokes 124 employed should be sufficiently numerous to create interstices between the spokes 124 sufficiently small to deter the passage of embolic material through the interstices.
The first ends 125 of the plurality a spokes 124 may be attached to the body 114 of the atrial pacer 112 at a common distance from the first end 118 of the atrial pacer 112. Alternatively, the first ends 125 of the plurality of spokes 124 may be attached to the body 114 of the atrial pacer 112 at varying distances from the first end 118 of the atrial pacer 112. Providing spokes 124 at a variety of distances from the first end 118 of the atrial pacer 112 may be useful to create a tortuous path to deter the flow of embolic material. For example, a first set of spokes 124 may have first ends 125 adjoining the atrial pacer 112 at a common distance from the first end 118 around the circumference of the atrial pacer 112. A second set of spokes may have first ends adjoining the atrial pacer 112 at a further distance from the first end 118 of the atrial pacer 112 than the first set of spokes 124. In addition, the second set of spokes may be oriented circumferentially to overlap with the interstices formed among the first set of spokes 124, as viewed from the first end 118 of the atrial pacer 112. Likewise, additional set of spokes 124 may be included to effect additional blockage of embolic material flow. Moreover, some or all of the spokes 124 may extend outwardly from the atrial pacer 112 along non-radial directions, to enhance blockage of embolic material.
The spokes 124 may be formed of any suitable material such as a metal or polymeric material like those described above with regard to the mesh-like filter 28. It is also desirable that the spokes 124 be sufficiently pliable to permit the spokes 124 to be disposed along the body 114 of the atrial pacer 112, as shown in
In addition, it is desirable that the spokes 124 be sufficiently resilient so that they expand away from the body 114 of the atrial pacer 112 once removed from the catheter, permitting the spokes 124 to engage the wall of left atrial appendage 210. In addition, the spokes 124 are formed sufficiently long and disposed at an angle away from the body 114 of the atrial pacer 112 to cause the second ends 127 of the spokes 124 to be biased against the wall of the left atrial appendage 210 to retain the cardiac stimulating device 100 in position. For example, the spokes 125 may have a length to allow the second ends 127 of the spokes 124 to terminate proximate the left atrial appendage opening. The spokes 124 are attached to the atrial pacer 112 at such a location as to permit the spokes 124 to partially occlude the opening of the left atrial appendage and to permit the first end 118 of the atrial pacer 112 to contact the wall of the atrial appendage 210.
In each of the above embodiments, the atrial pacer 12, 112 may include a power source 16, 116, such as a rechargeable battery, within the generally elongated body 14, 114 along with appropriate circuitry known for the operation of atrial sensing and stimulating devices. Alternatively or additionally, the cardiac stimulating device 10, 100 may include a lead wire 32, 132 to provide power and/or a control signal to the atrial pacer 12, 112 from a remote device. A control unit for use external to the left atrial appendage 210, or external to a patient's body, may be provided for housing circuitry of the atrial pacer 12, 112. Providing such a control unit may also be desirable, since inclusion of control circuitry therein may permit the atrial pacer 12, 112 to have a smaller overall the size.
Referring to
The control unit 302 further includes control circuitry 310 for processing the signal detected by the sensor 304 and controlling the stimulator 308 in response to the detected signal. For example, when the control circuitry 310 receives a signal from the sensor 304 indicative of NRAF of the left atrial appendage 210, the control circuitry delivers a control signal to the stimulator 308 to cause the stimulator 308 to stimulate the left atrial appendage 210 to alleviate the NRAF. Hence, by correcting NRAF, formation of blood clots in the left atrial appendage 210 is reduced by limiting the presence of stagnant blood in the left atrial appendage 210. The control unit 302 communicates with the stimulator 308 via an optional lead wire 309 or via wireless communication.
Wireless communication can be effected via optional antennas 314, 315 connected to the control unit 302 and the stimulator 308, respectively. The antenna 315 of the stimulator 308 may be disposed, for example, at the second end 30, 130 of the atrial pacer 12, 112. The control unit 302 may include a power source 312 to power the control unit 302 and to optionally power the stimulator 308 via lead wire 307.
Referring to
In addition, as shown in
After insertion of the cardiac stimulating device 10, 100 into the heart so that the filtration device 28, 126 expands and sensing device 22, 122 or sensor 304, 404 is placed in sensing contact with the left atrial appendage 210, the cardiac stimulating device 10, 100 monitors for the presence of NRAF. Upon detection of NRAF, the stimulator 23, 123 applies a correcting stimulating electrical signal to the left atrial appendage 210 in response to the detected NRAF condition. By such treatment of the left atrial appendage 210 to minimize NRAF, the formation of blood clots attributable to NRAF is minimized. In addition, the presence of the filtration device 28, 126 provides continuous filtration of the blood exiting the left atrial appendage 210, so as to prevent the egress of emboli therefrom.
These and other advantages of the present invention will be apparent to those skilled in the art. Accordingly, it will be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. For example, the atrial pacer could be replaced and/or adapted to function as a ventricular defibrillator to treat ventricular tachycardia. Likewise, the atrial pacer could be replaced by a device that functions as a combined atrial pacer and ventricular defibrillator. It should therefore be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention as set forth in the claims.
Claims
1. A cardiac stimulating apparatus comprising:
- a stimulator comprising an end for making at least one of sensing and stimulating contact with a wall of a heart, said stimulator comprising at least one of a sensor and a stimulator; and
- a filtration device mounted to said stimulator distal the end thereof and adapted for deterring movement of emboli through the filtration device.
2. The cardiac stimulating apparatus according to claim 1 wherein the filtration device comprises a plurality of spokes.
3. The cardiac stimulating apparatus according to claim 2 wherein the spokes include tines to attach the filtration device to the heart.
4. The cardiac stimulating apparatus according to claim 1 wherein the spokes extend generally radially outwardly from the stimulator.
5. The cardiac stimulating apparatus according to claim 1 wherein the filtration device comprises a mesh.
6. The cardiac stimulating apparatus according to claim 1 wherein the filtration device includes at least one of an expandable mesh and a plurality of expandable spokes.
7. The cardiac stimulating apparatus according to claim 6 wherein said one of said expandable mesh and said plurality of expandable spokes are collapsible to be disposed near the stimulator for implantation into the heart through a catheter.
8. The cardiac stimulating apparatus according to claim 1 wherein stimulator includes a control unit adapted to be disposed external to the heart.
9. The cardiac stimulating apparatus according to claim 8 wherein the control unit is adapted to be in wireless communication with the sensor.
10. The cardiac stimulating apparatus according to claim 8 wherein the control unit is adapted to be in wireless communication with the stimulator.
11. The cardiac stimulating apparatus according to claim 1 wherein the stimulator is adapted to apply a stimulating signal to the heart wall and the sensor is adapted to be in sensing contact with the heart wall.
12. The cardiac stimulating apparatus according to claim 1 comprising:
- i) a charger adapted to be disposed external to a patient's body for providing a power signal in the form of electromagnetic energy; and
- ii) an energizer adapted to be disposed internal to a patient's body for receiving the power signal provided by the generator unit to energize said stimulator.
13. The cardiac stimulating apparatus according to claim 12 wherein the generator unit comprises a first coil for transmitting the power signal and the energizing unit comprises a second coil for receiving the power signal.
14. A cardiac stimulating apparatus comprising:
- a stimulator comprising an elongated body adapted at one end thereof for making at least one of sensing and stimulating contact with a wall of an atrial appendage of a heart, said stimulator comprising an atrial sensor and an atrial stimulator disposed in said elongated body; and
- a filtration device mounted to said elongated body distal the one end thereof and adapted for deterring movement of emboli between the atrial appendage and an atrium of the heart.
15. The cardiac stimulating apparatus according to claim 14 wherein the filtration device comprises a plurality of spokes.
16. The cardiac stimulating apparatus according to claim 15 wherein the spokes include tines to attach the filtration device to the atrial appendage.
17. The cardiac stimulating apparatus according to claim 14 wherein the spokes extend generally radially outwardly from the stimulator.
18. The cardiac stimulating apparatus according to claim 14 wherein the filtration device comprises a mesh.
19. The cardiac stimulating apparatus according to claim 14 wherein the filtration device includes at least one of an expandable mesh and a plurality of expandable spokes.
20. The cardiac stimulating apparatus according to claim 19 wherein said one of said expandable mesh and said plurality of expandable spokes are collapsible to be disposed near the stimulator for implantation into the atrial appendage through a catheter.
21. The cardiac stimulating apparatus according to claim 14 wherein the stimulator includes a control unit adapted to be disposed external to the heart.
22. The cardiac stimulating apparatus according to claim 21 wherein the control unit is adapted to be in wireless communication with the sensor.
23. The cardiac stimulating apparatus according to claim 21 wherein the control unit is adapted to be in wireless communication with the stimulator.
24. The cardiac stimulating apparatus according to claim 14 wherein the stimulator is adapted to apply a stimulating signal to the wall of the atrial appendage and the sensor is adapted to be in sensing contact with a wall of the atrial appendage.
25. The cardiac stimulating apparatus according to claim 14 comprising:
- i) a charger adapted to be disposed external to a patient's body for providing a power signal in the form of electromagnetic energy; and
- ii) an energizer adapted to be disposed internal to a patient's body for receiving the power signal provided by the generator unit to energize said stimulator.
26. The cardiac stimulating apparatus according to claim 25 wherein the generator unit comprises a first coil for transmitting the power signal and the energizing unit comprises a second coil for receiving the power signal.
Type: Application
Filed: Jul 23, 2004
Publication Date: Jan 6, 2005
Inventor: Ramesh Pappu (Cherry Hill, NJ)
Application Number: 10/897,504