Cardiac assist system using helical arrangement of contractile bands and helically-twisting cardiac assist device

Abstract

A cardiac assist system using a helical arrangement of contractile bands and a helically-twisting cardiac assist device are disclosed. One embodiment discloses a cardiac assist system comprising at least one contractile elastic band helically arrangement around a periphery of a patient's heart, where upon an actuation the band contracts helically, thereby squeezing the heart and assisting the pumping function of the heart. Another embodiment discloses a helically twisting cardiac-apex assist device comprising an open, inverted, substantially conical chamber with two rotatable ring portions of different diameters located at the base and apex of the chamber, with a plurality of substantially helical connecting elements positioned substantially flush with the chamber wall and connecting the two rotatable ring portions, whereby a relative twisting motion of the two rings causes a change in volume of the chamber thereby assisting the cardiac pumping function.

Claims

1. A cardiac assist system comprising: a single contractile elastic band arranged helically around and encircling a periphery of a patient's heart such that the contractile elastic band does not penetrate the patient's heart, wherein the contractile elastic band is adapted to contract helically upon actuation with such contraction due to a contractile material property of the band such that the heart is squeezed and the pumping function of the heart is assisted, and wherein the contractile elastic band comprises only two free ends secured to each other at an attachment point.

2. The system of claim 1, wherein the contractile elastic band is arranged in a shape of a helix or a double helix.

3. The system of claim 1, wherein the contractile elastic band consists essentially of a material selected from biocompatible elastic materials, viscoelastic materials, active polymers, shape-memory alloys, natural contractile muscle bands, and artificial contractile muscle bands.

4. The system of claim 1, wherein the contractile elastic band is adapted to contract helically upon actuation that occurs via specific contraction wave propagation.

5. The system of claim 1, where the contractile elastic band covers up the infarcted and ischemic areas of the heart's epicardial surface, thereby preventing aneurismal remodeling of the heart.

6. The system of claim 1, wherein the contractile elastic band overlaps itself.

7. A surgical method comprising the act of attaching a single contractile elastic band around a patient's heart in a helical arrangement encircling the heart such that the contractile elastic band does not penetrate the heart, wherein only the contractile elastic band is implanted during the surgical procedure, and wherein the contractile elastic band comprises only two free ends secured to each other at an attachment point.

8. The method of claim 7, wherein the contractile elastic band is adapted to contract helically with such contraction due to a contractile material property of the band.

9. The method of claim 8, wherein the contractile elastic band consists essentially of a material selected from biocompatible elastic materials, viscoelastic materials, active polymer, natural contractile muscle bands, shape memory alloys, and artificial contractile muscle bands.

10. The method of claim 7, further comprising overlapping the contractile elastic band with itself.

11. The method of claim 7, wherein the contractile band is adapted to contract helically and assist ventricular ejection of blood during systole.

12. The method of claim 11, wherein attaching the single contractile elastic band around the patient's heart in the helical arrangement encircling the heart is performed such that the contractile elastic band contracts helically and assists ventricular ejection of blood during systole.

13. A cardiac assist system consisting essentially of: a single contractile elastic band assembly arranged helically around and encircling a periphery of a patient's heart such that the contractile elastic band does not penetrate the patient's heart, wherein the contractile elastic band comprises only two free ends secured to each other at an attachment point, and where upon actuation the contractile band contracts helically with such contraction due to a contractile material property of the band, thereby squeezing the heart and assisting the pumping function of the heart.

14. The system of claim 13, wherein the contractile elastic band overlaps itself.

15. The system of claim 1, wherein the contractile band is adapted to contract helically and assist ventricular ejection of blood during systole.

16. The system of claim 13, wherein the single contractile band is adapted to contract helically and assist ventricular ejection of blood during systole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The objects, features and advantages of the present invention will be apparent from the following detailed descriptions of the various aspects of the invention in conjunction with reference to the following drawings, where:

(2) FIG. 1A is a front-view illustration showing two possible arrangements of a contractile band grasping a heart;

(3) FIG. 1B is a back view illustration showing two possible arrangements of a contractile band grasping a heart;

(4) FIG. 1C is a bottom view illustration showing two possible arrangements of a contractile band grasping a heart;

(5) FIG. 2 is an illustration showing the contours of heart myofibril structure independent of the heart;

(6) FIG. 3 is an illustration showing the helically-twisting cardiac assist device of the present invention;

(7) FIG. 4A is an illustration showing the helically-twisting cardiac assist device of the present invention in elongated position and attached with a heart;

(8) FIG. 4B is an illustration showing the helically-twisting cardiac assist device of the present invention in contracted position and attached with a heart;

(9) FIG. 5A is an illustration showing a heart with a dotted line indicating the approximate location of the partial, distal bi-ventriculectomy;

(10) FIG. 5B is an illustration showing the helically-twisting cardiac assist device of the present invention attached with the apex of a heart; and

(11) FIG. 5C is an illustration showing the helically-twisting cardiac assist device of the present invention with attachment points to the base of a heart.

DETAILED DESCRIPTION

(12) The present invention relates to a system and device for assisting cardiac pumping function and, more specifically, to a system and device which assists the cardiac pumping function through a helical arrangement of contractile members. The following description is presented to enable one of ordinary skill in the art to make and use the invention and to incorporate it in the context of particular applications. Various modifications, as well as a variety of uses in different applications will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

(13) In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.

(14) The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification, (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is only one example of a generic series of equivalent or similar features.

(15) Furthermore, any element in a claim that does not explicitly state means for performing a specified function, or step for performing a specific function, is not to be interpreted as a means or step clause as specified in 35 U.S.C. Section 112, Paragraph 6. In particular, the use of step of or act of in the claims herein is not intended to invoke the provisions of 35 U.S.C. 112, Paragraph 6.

(16) Further, if used, the labels left, right, front, back, top, bottom, forward, reverse, clockwise and counter clockwise have been used for convenience purposes only and are not intended to imply any particular fixed direction. Instead, they are used to reflect relative locations and/or directions between various portions of an object.

(17) (1) Introduction

(18) The present invention relates to a system and device for assisting cardiac pumping function and, more specifically, to a system and device which assists the cardiac pumping function through a helical arrangement of contractile members. The description section below is divided into two parts corresponding to the two main embodiments of the present invention. Section (2) below discloses a cardiac assist system using a helical arrangement of contractile bands and surgical method for implanting the same, while section (3) discloses a helically-twisting cardiac assist device and surgical method for implanting the same.

(19) (2) Cardiac Assist System Using Helical Arrangement of Contractile Bands

(20) In one aspect, the present invention teaches a cardiac assist system that works based on the contraction of at least one contractile elastic band 100 grasping the heart 102 as shown in FIGS. 1A-C. The contractile band 100 may be arranged in a helix, a double helix, or any other substantially helical arrangement which mimics the natural pumping function of the heart. The arrangements shown in FIGS. 1A-C comprise two possible arrangements of a single contractile band 100 arranged in a double helix around the heart 102, attached to itself at an attachment point 104. The helical band arrangement assists both left and right ventricles during diastole to receive blood from the atria more efficiently, and helps both ventricles to eject the blood more effectively during systole and to improve both local and global cardiac function. The elastic bands 100 can be made of any types of biocompatible elastic or viscoelastic materials such as, but not limited to elastomers like Resilin, silicone rubber, or Polyisobutylen. Other materials suitable for the elastic bands are shape-memory alloys, natural contractile muscle bands, and artificial contractile muscle bands. The bands may also have a framework made of shape-memory materials/fibers.

(21) The system works based on the idea that if contraction waves transmit through the bands at optimal angles around the heart, its pumping efficiency would be higher than if the contraction waves transmit radially or longitudinally. The idea for the system is based on naturally occurring myofibril structure, which can be seen in recent MRI data as detailed in Helm, P., et al., Measuring and Mapping Cardiac Fiber and Laminar Architecture Using Diffusion Tensor MR Imaging. Ann NY Acad Sci, 2005. 1047(1): p. 296-307. Unlike the myoplasty concept this system not only assists the heart globally but also reinforces local function. FIG. 2 is an illustration showing the contours of the myofibril structure 204 independent of the heart.

(22) Another aspect of the cardiac assist system is synchronization of the contraction of the contractile bands with the natural heart motion. Synchronization would be made by devices such as, but not limited to, external and/or internal pacemakers. The activation of the band(s) can mimic the Purkinje activation of the cardiac muscle, i.e. starting at the apex and propagating to the periphery, or follow any other specific contraction wave propagation scheme. This system can also have a feedback mechanism where the contraction waves sent through the bands are adjusted based on inputs received from the heart or vasculature; inputs such as but not limited to blood pressure, volume, ECG, pulse pressure, pace maker signal, etc. As a result the device would be able to self-adjust to changing demands of the heart. In another aspect, the system covers the infarcted/ischemic areas of the epicardial surface of the heart to prevent aneurismal remodeling. The present invention also improves coronary blood flow by accentuating the cardiac motion and pumping function of the heart.

(23) (3) Helically-Twisting Cardiac Assist Device

(24) In another aspect, the present invention teaches a cardiac assist device that works based on a helically twisting mechanism. The device assists both left and right ventricles during diastole to receive blood from the atria more efficiently, and helps both ventricles to eject the blood more effectively during systole. The shell of the device, as shown in FIG. 3, is an open, inverted, substantially conical chamber 300 having an apex 302, a base 304, and an elastic chamber wall 306, the chamber being of a shape and size appropriate for fitting snugly over the apex of a heart. Inside the conical chamber are two rotatable ring portions of different diameters, the ring with the larger diameter 308 circumscribing the base 304 of the conical chamber 300, and the ring with the smaller diameter 310 located near the apex 302 of the chamber 300. A plurality of substantially helical connecting elements 311 connects the two ring portions 308 and 310 and is substantially flush with the chamber wall 306. The device further comprises an actuator portion 312 connected with the smaller ring 310, where the actuator 312 is configured for anchoring inside a patient's chest cavity. The actuator 312 powers a twisting motion 314 of one ring relative to the other. The actuator 312 can be a motor such as a twisting rotor, which can be attached anywhere inside the chest, or the actuator 312 can be an internal power source such as latissimus dorsi muscle or any other internal structure. Twisting 314 the rings 308 and 310 in opposite relative directions, as shown in FIGS. 4A-B, results in deviation of the helical elements 311 from their original angles, which increases or decreases the distance 400 between two rings. In the case of increasing distance, the chamber induced dilation results in generation of negative pressure during diastole. In contrast, by decreasing the rings' relative distance, the device provides extra pumping force during systole. FIGS. 4A-B also show the device attached with a heart 402. Furthermore, the actuation of the device can be synchronized with the motion of the heart by an external or internal pace-maker.

(25) The rings and helical elements of the device can be made of different selections of shape memory material such as nitinol and/or composite materials. The chamber wall can be made of any type of biocompatible elastic or viscoelastic materials such as, but not limited to, elastomers like Resilin, silicone rubber, Polyisobutylen, etc.

(26) The present invention also includes a surgical procedure to implant the device via two or more sequential stages. The first stage, as shown in FIG. 5A, is a partial, distal bi-ventriculectomy 500 with preservation of the anatomical structures such as but not limited to ventricular septum 502 and the papillary muscles. In the second stage, as shown in FIG. 5B, the device 504 is attached to the ventricles 506. The device 504 can be stitched directly to the ventricles 506 and/or supported by additional connections to other internal organs such as but not limited to the sternum or the base of the heart 508. The papillary muscles, interventricular septum 502 and the other structures can be attached to the device 504 with preservation of their blood supply.