Heart wall actuation system for the natural heart with shape limiting elements

Abstract

An actuation system for assisting the operation of the natural heart includes an actuator element adapted to be positioned proximate a portion of a heart wall. The actuator element is operable for acting on the heart wall portion to effect a change in the shape of the heart. A shape-limiting element is configured for being positioned proximate a heart wall. The shape-limiting element is operable for flexing to assume a curvature no greater than a predetermined curvature when the heart wall is acted upon and maintaining that predetermined curvature to control the shape of the actuated heart.

Description

RELATED APPLICATIONS [0001] This application is a Divisional of U.S. patent application Ser. No. 10 / 223,271, filed on Aug. 19, 2002, the entire disclosure of which is incorporated herein by reference.FIELD OF THE INVENTION [0002] This invention relates generally to assisting the natural heart in operation by actuating a wall of the natural heart, and more specifically to facilitating such actuation without damage to the heart tissue. BACKGROUND OF THE INVENTION [0003] The natural human heart and accompanying circulatory system are critical components of the human body and systematically provide the needed nutrients and oxygen for operation of the body. As such, the proper operation of the circulatory system, and particularly, the proper operation of the heart, are critical in the life, health and well being of a person. A physical ailment or condition which compromises the normal and healthy operation of the heart can therefore be particularly critical and may result in a condition ...

AI Technical Summary

Benefits of technology

[0021] The present invention addresses the above objectives and other objectives by providing an actuation system for assisting the operation of the natural heart which utilizes a shape-limiting element configured for being positioned proximate a heart wall to control the shape of the heart when it is actuated. The shape-limiting element is operable for bending or flexing to a predetermined curvature or multiple curvatures when the heart wall is acted upon and maintaining those predetermined curvatures to control the shape of the actuated heart and limit any undesirable tensile or compressive strain induced upon the heart tissue. In one embodiment, the shape-limiting element is utilized within an actuation system comprising a framework for interfacing with the natural heart, which includes an element configured for being anchored to tissue of the heart. An actuator element is adapted for being coupled to the framework and is configured for extending proximate a portion of a heart wall and acting on the heart wall to effect a change in the shape of the heart. The shape-limiting element may be coupled to the actuator element such that the forces on the heart wall are also forces that vary the shape of the shape-limiting element.

Problems solved by technology

A physical ailment or condition which compromises the normal and healthy operation of the heart can therefore be particularly critical and may result in a condition which must be medically remedied.

More specifically, the natural heart, or rather the cardiac tissue of the heart, can degrade for various reasons to a point where the heart can no longer provide sufficient circulation of blood for maintaining the health of a patient at a desirable level.

In fact, the heart may degrade to the point of failure and thereby may not even be able to sustain life.

In using artificial hearts and / or assist devices, a particular problem stems from the fact that the materials used for the interior lining of the chambers of an artificial heart are in direct contact with the circulating blood.

Such contact may enhance undesirable clotting of the blood, may cause a build-up of calcium, or may otherwise inhibit the blood's normal function.

As a result, thromboembolism and hemolysis may occur.

Additionally, the lining of an artificial heart or a ventricular assist device can crack, which inhibits performance, even when the crack is at a microscopic level.

Moreover, these devices must be powered by a power source, which may be cumbersome and / or external to the body.

Such drawbacks have limited the use of artificial heart and assist devices to applications having too brief of a time period to provide a real lasting health benefit to the patient.

Before replacing an existing organ with another, the substitute organ must be “matched” to the recipient, which can be, at best, difficult, time consuming, and expensive to accomplish.

Furthermore, even if the transplanted organ matches the recipient, a risk exists that the recipient's body will still reject the transplanted organ and attack it as a foreign object.

As currently used, skeletal muscle cannot alone typically provide sufficient and sustained pumping power for maintaining circulation of blood through the circulatory system of the body.

Typically, bypass systems of this type are complex and large, and, as such, are limited to short term use, such as in an operating room during surgery, or when maintaining the circulation of a patient while awaiting receipt of a transplant heart.

The size and complexity effectively prohibit use of bypass systems as a long-term solution, as they are rarely portable devices.

Furthermore, long-term use of a heart-lung machine can damage the blood cells and blood borne products, resulting in post surgical complications such as bleeding, thromboembolism function, and increased risk of infection.

Although somewhat effective as a short-term treatment, the existing pumping devices have not been suitable for long-term use.

This “active filling” of the chambers with blood limits the ability of the pumping device to respond to the need for adjustments in the blood volume pumped through the natural heart, and can adversely affect the circulation of blood to the coronary arteries.

Furthermore, natural heart valves, between the chambers of the heart and leaching into and out of the heart, are quite sensitive to wall distortion and annular distortion.

The compressive movement patterns that reduce a chamber's volume and distort the heart walls may not necessarily facilitate valve closure (which can lead to valve leakage).

Another major obstacle with long term use of such pumping devices is the deleterious effect of forceful contact of different parts of the living internal heart surface (endocardium), one against another, due to lack of precise control of wall actuation.

However, it can compromise the integrity of the living endothelium.

More specifically, the heart walls may have a tendency to become overly distended, or take on sharp curvatures, in certain areas based upon the indentation of those walls in other areas.

Such unnatural shaping of the heart tissue may be damaging to the tissue.

Therefore, when utilizing a heart wall actuation system, one issue to be addressed is the shape of the walls when the system is actuated, and the variance of that shape from the natural shape that the heart would assume when pumping normally.

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