Patent Application
20060030881
The present invention relates generally to the field of treating congestive heart failure and more specifically, to a device and method for partitioning a patient's heart chamber and a system for delivering the treatment device.
Congestive heart failure (CHF) is characterized by a progressive enlargement of the heart, particularly the left ventricle and is a major cause of death and disability in the United States. Approximately 500,000 cases occur annually in the U.S. alone. As the patient's heart enlarges, it cannot efficiently pump blood forward with each heart beat. In time, the heart becomes so enlarged the heart cannot adequately supply blood to the body. Even in healthy hearts only a certain percentage of the blood in a patient's left ventricle is pumped out or ejected from the chamber during each stroke of the heart. The pumped percentage, commonly referred to as the “ejection fraction”, is typically about sixty percent for a healthy heart. A patient with congestive heart failure can have an ejection fraction of less than 40% and sometimes lower. As a result of the low ejection fraction, a patient with congestive heart failure is fatigued, unable to perform even simple tasks requiring exertion and experiences pain and discomfort. Further, as the heart enlarges, the internal heart valves such as the mitral valve, cannot adequately close. An incompetent mitral valve allows regurgitation of blood from the left ventricle back into the left atrium, further reducing the heart's ability to pump blood forewardly.
Congestive heart failure can result from a variety of conditions, including viral infections, incompetent heart valves (e.g. mitral valve), ischemic conditions in the heart wall or a combination of these conditions. Prolonged ischemia and occlusion of coronary arteries can result in myocardial tissue in the ventricular wall dying and becoming scar tissue. Once the myocardial tissue dies, it is less contractile (sometimes non-contractile) and no longer contributes to the pumping action of the heart. It is referred to as hypokinetic. As the disease progresses, a local area of compromised myocardium may bulge out during the heart contractions, further decreasing the heart's ability to pump blood and further reducing the ejection fraction. In this instance, the heart wall is referred to as dyskinetic or akinetic. The dyskinetic region of the heart wall may stretch and eventually form an aneurysmic bulge.
Patients suffering from congestive heart failure are commonly grouped into four classes, Classes I, II, III and IV. In the early stages, Classes I and II, drug therapy is presently the most commonly prescribed treatment. Drug therapy typically treats the symptoms of the disease and may slow the progression of the disease, but it can not cure the disease. Presently, the only permanent treatment for congestive heart disease is heart transplantation, but heart transplant procedures are very risky, extremely invasive and expensive and are performed on a small percentage of patients. Many patient's do not qualify for heart transplant for failure to meet any one of a number of qualifying criteria, and, furthermore, there are not enough hearts available for transplant to meet the needs of CHF patients who do qualify.
Substantial effort has been made to find alternative treatments for congestive heart disease. For example, surgical procedures have been developed to dissect and remove weakened portions of the ventricular wall in order to reduce heart volume. This procedure is highly invasive, risky and expensive and is commonly only done in conjunction with other procedures (such as heart valve replacement or coronary artery by-pass graft). Additionally, the surgical treatment is usually limited to Class IV patients and, accordingly, is not an option for patients facing ineffective drug treatment prior to Class IV. Finally, if the procedure fails, emergency heart transplant is the only presently available option.
Other efforts to treat CHF include the use of an elastic support, such as an artificial elastic sock placed around the heart to prevent further deleterious remodeling.
Additionally, mechanical assist devices have been developed as intermediate procedures for treating congestive heart disease. Such devices include left ventricular assist devices and total artificial hearts. A left ventricular assist device includes a mechanical pump for increasing blood flow from the left ventricle into the aorta. Total artificial heart devices, such as the Jarvik heart, are usually used only as temporary measures while a patient awaits a donor heart for transplant.
Recently, improvements have been made in treating patient's with CHF by implanting pacing leads in both sides of the heart in order to coordinate the contraction of both ventricles of the heart. This technique has been shown to improve hemodynamic performance and can result in increased ejection fraction from the right ventricle to the patient's lungs and the ejection fraction from the left ventricle to the patient's aorta. While this procedure has been found to be successful in providing some relief from CHF symtoms and slowed the progression of the disease, it has not been able to stop the disease.
The present invention is directed to a ventricular partitioning device and method of employing the device in the treatment of a patient with congestive heart failure (CHF). Specifically, the device partitions a chamber of the patient's heart into a main productive portion and a secondary non-productive portion. This partitioning reduces the total volume of the heart chamber, reduces the stress applied to the heart and, as a result, improves the ejection fraction thereof.
A partitioning device embodying features of the invention has a reinforced partitioning component with a concave, pressure receiving surface which defines in part the main productive portion of the partitioned heart chamber when secured within the patient's heart chamber.
The reinforced partitioning component preferably includes a hub and a membrane forming the pressure receiving surface. The partitioning component is reinforced by a radially expandable frame component formed of a plurality of ribs.
The ribs of the expandable frame have distal ends secured to the central hub and free proximal ends. The distal ends are preferably secured to the central hub to facilitate radial self expansion of the free proximal ends of the ribs away from a centerline axis. The distal ends of the ribs may be pivotally mounted to the hub and biased outwardly or fixed to the hub and formed of material such as superelastic NiTi alloy which allows for compressing the free proximal ends of the ribs toward a centerline axis into a contracted configuration and when released allow for their self expansion to an expanded configuration.
The free proximal ends of the ribs are configured to engage and preferably penetrate the tissue lining the heart chamber to be partitioned so as to secure the peripheral edge of the partitioning component to the heart wall and fix the partitioning component within the chamber so as to partition the chamber in a desired manner. The tissue penetrating proximal tips are configured to penetrate the tissue lining at an angle approximately perpendicular to a center line axis of the partitioning device. The tissue penetrating proximal tips of the ribs may be provided with barbs, hooks and the like which prevent withdrawal from the tips from the heart wall.
The ribs in their expanded configuration angle outwardly from the hub and the free proximal ends curve outwardly so that the membrane secured to the ribs of the expanded frame forms a trumpet-shaped, pressure receiving surface.
The partitioning membrane in the expanded configuration has radial dimensions from about 10 to about 160 mm, preferably about 50 to about 100 mm, as measured from the center line axis.
The partitioning device may be delivered percutaneously or intraoperatively. One particularly suitable delivery catheter has an elongated shaft, a releasable securing device on the distal end of the shaft for holding the partitioning device on the distal end and an expandable member such as an inflatable balloon on a distal portion of the shaft proximal to the distal end to press the interior of the recess formed by the pressure receiving surface to ensure that the tissue penetrating tips or elements on the periphery of the partitioning device penetrate sufficiently into the heart wall to hold the partitioning device in a desired position to effectively partition the heart chamber.
The partitioning device embodying features of the invention is relatively easy to install and it substantially improves the pumping action of the heart and provides an increase in the ejection fraction of the patient's heart chamber. These and other advantages of the invention will become more apparent from the following detailed description of the invention and the accompanying exemplary drawings.
As shown in more detail in
The connector bar 20 of the hub 12, as will be described later, allows the partitioning device 10 to be secured to a delivery system delivery and to be released from the delivery system within the patient's heart chamber. The distal ends 15 of the reinforcing ribs 14 are secured within the hub 12 in a suitable manner or they may be secured to the surface defining the inner lumen or they may be disposed within channels or bores in the wall of the hub 12. The ribs 14 are preshaped so that when not constrained other than by the membrane 11 secured thereto (as shown in
The guide catheter has an inner lumen 33 extending between the proximal end 34 and distal end 35. A hemostatic valve (not shown) may be provided at the proximal end 34 of the guide catheter 31. A flush port 36 on the proximal end 34 of guide catheter 31 is in fluid communication with the inner lumen 33.
The delivery catheter 32 has an outer shaft 40 with an inner lumen 41 and a proximal injection port 42, an inner shaft 43 disposed within the inner lumen 41 with a first lumen 44 and a second lumen 45. Balloon inflation port 46 is in fluid communication with the first lumen 44 and flush port 47 is in fluid communication with the second lumen 45. Torque shaft 48 is rotatably disposed within the second lumen 44 of the inner shaft 43 and has an injection port 49 provided at its proximal end 50 in fluid communication with the inner lumen 51 of the torque shaft. The torque shaft 48 is preferably formed at least in part of a hypotube formed of suitable material such as superelastic NITINOL or stainless steel. A torque knob 52 is secured to the proximal end 50 of torque shaft 48 distal to the injection port 49. A helical coil screw 53 is secured to the distal end 54 of the torque shaft 48 and rotation of the torque knob 52 on the proximal end 50 of the torque shaft 48 rotates the screw 53 on the distal end 54 of torque shaft 48 to facilitate deployment of a partitioning device 10. A inflatable balloon 55 is sealingly secured to the distal end of the inner shaft 43 and has an interior 56 in fluid communication with the first lumen 44. Inflation fluid may be delivered to the interior 56 through port 44a in the portion of the inner shaft 43 extending through the balloon 55. Inflation of the balloon 55 by inflation fluid through port 57 facilitates securing the partitioning component 10.
To deliver the partitioning component 10, it is secured to the distal end of the delivery catheter 32 by means of the helical coil screw 53. The partitioning component 10 is collapsed to a first, delivery configuration which has small enough transverse dimensions to be slidably advanced through the inner lumen 33 of the guide catheter 31. Preferably, the guide catheter 31 has been previously percutaneously introduced and advanced through the patient's vasculature, such as the femoral artery, in a conventional manner to the desired heart chamber. The delivery catheter 32 with the partitioning component 10 attached is advanced through the inner lumen 33 of the guide catheter 31 until the partitioning component 10 is ready for deployment from the distal end of the guide catheter 31 into the patient's heart chamber 58 to be partitioned.
The partitioning component 10 mounted on the screw 53 is urged partially out of the inner lumen 33 of the guide catheter 31 until the hub 12 engages the heart wall as shown in
With the partitioning component deployed within the heart chamber and preferably partially secured therein, inflation fluid is introduced through the inflation port 46 into first lumen 44 of inner shaft 43 of the delivery catheter 32 where it is directed through port 44a into the balloon interior 56 to inflate the balloon. The inflated balloon presses against the pressure receiving surface 18 of the partitioning component 10 to ensure that the sharp proximal tips 21 are pressed well into the tissue lining the heart chamber.
With the partitioning device 10 properly positioned within the heart chamber, the knob 52 on the torque shaft 48 is rotated counter-clockwise to disengage the helical coil screw 53 of the delivery catheter 32 from the hub 12. The counter-clockwise rotation of the torque shaft 48 rotates the helical coil screw 53 which rides on the connector bar 20 secured within the hub 12. Once the helical coil screw 53 disengages the connector bar 20, the delivery system 30, including the guide catheter 31 and the delivery catheter 32, may then be removed from the patient.
The proximal end of the guide catheter 31 is provided with an flush port 36 to inject therapeutic or diagnostic fluids through the inner lumen 33. Similarly, the proximal end of the delivery catheter 32 is provided with a flush port 42 in communication with inner lumen 41 for essentially the same purpose. An inflation port 46 is provided on the proximal portion of the delivery catheter for delivery of inflation fluid through the first inner lumen 44 to the interior 56 of the balloon 55. Flush port 47 is provided in fluid communication with the second inner lumen 45 of the inner shaft 43. An injection port 49 is provided on the proximal end of the torque shaft 48 in fluid communication with the inner lumen 51 of the torque shaft for delivery of a variety of fluids.
The partitioning component 10 partitions the patient's heart chamber 57 into a main productive or operational portion 58 and a secondary, essentially non-productive portion 59. The operational portion 58 is much smaller than the original ventricular chamber 57 and provides for an improved ejection fraction. The partitioning increases the ejection fraction and provides an improvement in blood flow. Over time, the non-productive portion 59 fills first with thrombus and subsequently with cellular growth. Bio-resorbable fillers such as polylactic acid, polyglycolic acid, polycaprolactone and copolymers and blends may be employed to initially fill the non-productive portion 59. Fillers may be suitably supplied in a suitable solvent such as DMSO. Other materials which accelerate tissue growth or thrombus may be deployed in the non-productive portion 59.
The partitioning device 10 is conveniently formed by placing a thermoplastic tube 60, e.g. polyethylene, over the ribs 14 of the frame 13 as shown in
While porous ePTFE material is preferred, the membrane 11 may be formed of suitable biocompatitble polymeric material which include Nylon, PET (polyethylene terephthalate) and polyesters such as Hytrel. The membrane 11 is preferably foraminous in nature to facilitate tissue ingrowth after deployment within the patient's heart. The delivery catheter 32 and the guiding catheter 31 may be formed of suitable high strength polymeric material such as PEEK (polyetheretherketone), polycarbonate, PET, Nylon, and the like. Braided composite shafts may also be employed.
To the extent not otherwise described herein, the various components of the partitioning device and delivery system may be formed of conventional materials and in a conventional manner as will be appreciated by those skilled in the art.
While particular forms of the invention have been illustrated and described herein, it will be apparent that various modifications and improvements can be made to the invention. Moreover, individual features of embodiments of the invention may be shown in some drawings and not in others, but those skilled in the art will recognize that individual features of one embodiment of the invention can be combined with any or all the features of another embodiment. Accordingly, it is not intended that the invention be limited to the specific embodiments illustrated. It is intended that this invention to be defined by the scope of the appended claims as broadly as the prior art will permit.
Terms such a “element”, “member”, “device”, “section”, “portion”, “step”, “means” and words of similar import, when used herein shall not be construed as invoking the provisions of 35 U.S.C. §112(6) unless the following claims expressly use the terms “means” followed by a particular function without specific structure or “step” followed by a particular function without specific action. Accordingly, it is not intended that the invention be limited, except as by the appended claims. All patents and patent applications referred to above are hereby incorporated by reference in their entirety.
