Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
2000-09-14
2002-10-08
Gibson, Roy D. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C607S100000, C607S105000
Reexamination Certificate
active
06463332
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to pericardial enhancement, and more particularly to methods and systems for modifying the pericardium to reduce or eliminate remodeling of the heart for patients suffering from or at risk of heart failure.
BACKGROUND OF THE INVENTION
A common form of heart disease involves cardiac dilation. Ventricular dilatation, for example, increases the load on the heart and decreases cardiac efficiency, producing symptoms of congestive heart failure. The ventricular walls grow thinner and more vulnerable as a result of ventricular dilatation and associated increase in wall stresses.
Healthy pericardium provides a constraint around the myocardium to prevent dilatation of the chambers of the heart. For patients suffering from or at risk of heart disease, the constraining forces of the pericardium may be inadequate to prevent dilatation of the chambers of the heart. The pericardium may decrease in rigidity and become excessively compliant, or the natural restraining capability of the pericardium may simply be inadequate to overcome the pressure produced by the cardiac dilation.
Cardiac reinforcement devices have been proposed for treating heart dilation. For example, U.S. Pat. No. 5,702,343 discloses a cardiac reinforcement device having a bio-compatible jacket to be placed over the epicardial surface of the heart to constrain cardiac expansion. U.S. Pat. No. 5,800,528 discloses a passive girdle to be wrapped around a heart muscle. The girdle is formed of unattached, linked loops designed to conform to the size and shape of the heart and to constrain the dilatation during diastole. U.S. Pat. No. 5,603,337 is directed to cardiomyoplasty in which a skeletal muscle is grafted around the heart. U.S. Pat. No. 4,536,893 discloses a device having expandable pumping chambers for receiving a pumping fluid to compress the myocardial wall.
Other cardiac muscle wraps are disclosed in Eli R. Capouya et al., “Girdling Effect of Nonstimulated Cardiomyoplasty on Left Ventricular Function,” 58 Ann. Thorac. Surg. 867-71 (1993); David A. Kass et al., “Reverse Remodeling from Cardiomyoplasty in Human Heart Failure,” 91 Circulation 2314-18 (May 1, 1995); Mikhail Vaynblat et al., “Cardiac Binding in Experimental Heart Failure,” 60 Ann. Thorac. Surg. 81-85 (1997); and Joong Hwan Oh et al., “The Effects of Prosthetic Cardiac Binding and Adynamic Cardiomyoplasty in a Model of Dilated Cardiomyopathy,” 116 J. Thorac. Cardiovasc. Surg. 148-53 (1998).
The use of radio frequency (RF) energy to induce heat in collagen containing tissue to alter collagen in tissue is known. For example, U.S. Pat. No. 5,458,596 discloses an orthopedic apparatus for delivering RF energy to ligaments, joint capsules and connective tissue. U.S. Pat. No. 5,785,705 discloses an RF ablation apparatus for controlled depth ablation of soft tissue.
Heat-induced shrinkage of collagen tissue has been used for various treatments in the heart. For example, PCT Publication No. WO 98/26738 discloses treating myocardial infarction by selectively heating the infarct scar. U.S. Pat. No. 5,928,224 discloses using heat and/or applying pressure to treat infected or damaged heart valve tissue. Other applications of heat-induced treatment include shrinking the chordae tendinae (WO 98/35638), closing or abrading the patent foramen ovale (WO 99/18871, WO 99/18870, WO 99/18862, U.S. Pat. No. 5,919,200), modifying the collagen fibers of the vein (WO 98/32367), and closing the ductus arteriosus (U.S. Pat. No. 5,827,268).
SUMMARY OF THE INVENTION
The present invention is generally directed to methods and systems for treating patients suffering from or at risk of heart failure. The invention modifies the pericardium to treat heart failure of the type wherein constraining forces of the pericardium on the heart are inadequate to prevent remodeling involving geometric alteration of the heart. The pericardium is enhanced by restoring, increasing, or improving its ability to restrain the heart and prevent dilation of the chambers of the heart. Specific embodiments of the invention cause stiffening, strengthening, tightening, reshaping, and/or shrinking of the pericardium to enhance the restraining and supporting capability of the pericardium around the heart.
The pericardium includes collagen-containing connective tissue. Collagen fibers shrink and tighten when elevated in temperature. This molecular response to temperature elevation is believed to be the result of rupture of the collagen stabilizing cross links and immediate contraction of the collagen fibers to about one-third of their original linear dimension. In addition, the caliber of the individual fibers increases greatly, over four fold, without changing the structural integrity of the connective tissue.
An aspect of the present invention is directed to a method for treating patients suffering from or at risk of heart failure of the type involving inhibiting or preventing remodeling of the heart, for example, by placing an elastic or inelastic constraint surrounding at least a part of the heart. The improvement includes modifying the pericardium under conditions to inhibit remodeling of the heart.
In some embodiments, modifying the pericardium includes heating at least a portion of the pericardium under conditions that shrink collagen within the pericardial tissue while retaining tissue viability. The pericardium may be heated in a pattern of spaced-apart lines in a grid. Alternatively, the entire pericardium may be heated. Selective heating may be performed, for example, below the AV groove or in a region overlying the left ventricle.
In a specific embodiment, the pericardium is heated by contacting the pericardial tissue with a probe that applies RF energy to the pericardial tissue. The RF energy may be applied in a monopolar manner or a bipolar manner. The probe may be placed in contact with the pericardial tissue on the outside of the pericardium or from within the pericardial space. When the pericardium is heated from the outside, the fat on the outside of the pericardium is preferably first removed by mechanical abrasion, thermal ablation, suction, chemicals, or the like.
In another embodiment, at least a portion of the pericardium is conductively heated by placing a heating element in contact with or in close proximity to the pericardial tissue and circulating a heated fluid through the heating element. The heating element will preferably contact the entire area to be reinforced.
In another embodiment, the pericardium is modified by applying a chemical to reduce compliance of the pericardium. The chemical may include glutaraldehyde. The chemical may be removed from the patient substantially contemporaneously with the application of the chemical.
In yet another embodiment, modifying the pericardium includes plicating the pericardium, for example, by suturing or clipping.
A target region of the pericardium that is to be modified may be isolated by anchoring a portion of the pericardium surrounding the target region to the myocardium. Suturing or clipping may be employed in anchoring the portion of the pericardium to the myocardium.
If an anastomosis site is present, a ring of the pericardium may be coupled with the myocardium around the anastomosis. The coupling may involve attaching the ring of pericardium to an annular piece of biomedical material and attaching the annular piece of biomedical material to the myocardium around the anastomosis.
Certain embodiments of the invention involve accessing a region of the pericardium for treatment. The pericardium may be accessed, for example, by surgically opening the patient's chest, forming an intercostal incision, or forming a subxiphoid access channel, or transvascularly via the venous system.
The pericardium may be treated while the heart remains beating or when the heart is stopped.
In accordance with another aspect of the invention, a method for treating patients suffering from or at risk of heart failure includes providing a device having a heating member, and placing the heating member in
Core Medical, Inc.
Gibson Roy D.
Lyon & Lyon LLP
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