Abstract:
A catheter device suitable for shrinking chordae tendineae of the human heart is provided having an energy conduit and a positioning device that facilitates the delivery of thermal energy, including coherent (laser) or non-coherent light, RF, microwave or ultrasound energy, to a predetermined region of the chordae tendineae or other collagen-containing tissue, such as the female urethra or the esophagus near the sphincter. The device comprises a tubular catheter containing an energy conduit, such as a fiber optic cable, adapted for delivering thermal energy to the tissue. The tubular catheter also contain a stabilizing device, disposed at its distal end, such as an asymmetrically shaped balloon or a retractable flexible metal hook. With the distal end of the catheter device positioned within a human heart, application of thermal energy to the chordae tendineae results in a shrinkage of the chordae, providing a treatment for primary mitral valve regurgitation.

Description:
FIELD OF THE INVENTION 
     The invention relates to devices for shrinking collagen in body tissue. More particularly, the invention relates to catheter devices for shrinking the chordae tendineae of the heart. 
     BACKGROUND OF THE INVENTION 
     The human heart consists of four muscular chambers: the right atrium, which connects to the right ventricle, and the left atrium, which connects to the left ventricle. The pumping action of the heart is achieved by contraction and relaxation of the heart muscles. The filling stage of the heart cycle is called diastole. The pumping stage is called systole. Both atria are filled at the same time during diastole and both ventricles expel their blood at the same time during systole. 
     During diastole, the heart chambers are at their largest volumes, and the atrioventricular valves, which separate the atria from the ventricles, are open. During systole, the heart muscles of the atria contract first, forcing their contents into the ventricles, and then, as the ventricles begin to contract, the increased ventricular pressure forces the atrioventricular valves to close, and the semilunar valves into the arteries to open, so that blood flows out of the heart and into the body tissues. Oxygen depleted blood is forced from the right ventricle into the lungs through the pulmonary artery, and oxygen rich blood is forced from the left ventricle into the remainder of the body through the aortic artery. 
     Each atrioventricular valve is composed of leaflets of connective tissue, called cusps, which are connected to the heart muscle tissue at the annulus of the aperture between the atrium and the ventricle. The unconnected portions of the cusps overlap with each other when the valves are in the closed position, such that the aperture between the chambers is completely closed. The cusps are stabilized and operated by roughly conical shaped muscles extending from the floor of the ventricles, called papillary muscles, which are connected to the cusps by fibrous, tendon-like structures called chordae tendineae (chordae). There is at least one papillary muscle for each cusp. The chordae begin at the apex of the cone of the papillary muscle and fan upward roughly to the periphery of the cusp. The chordae tendineae are the “guy wires” for the cusps of the atrioventricular valves. The mitral valve, between the left atrium and ventricle, has two cusps, while the tricuspid valve, between the right atrium and ventricle, has three cusps. 
     The pumping efficiency of the heart can be greatly diminished if the atrioventricular valves malfunction, allowing leakage of the blood from ventricle to atrium. A particularly common problem is weakening or stretching of the chordae, which condition allows the cusps of the affected atrioventricular valves to prolapse into the atrium during systole. Valve prolapse lowers the pumping efficiency of the heart by allowing a portion of the blood to flow in the wrong direction. Valve prolapse is particularly common with the mitral valve, a condition known as primary mitral valve regurgitation, but can also occur with the tricuspid valve. Other conditions which cause mitral valve malfunction include excessive lengthening or thickening of the cusps and the annulus of the valve becoming stretched or loose. Malfunction of the mitral valve occurs in an estimated 1.4% of the population and can lead to a variety of problems, including weakness, persistent nausea, atrial or ventricular fibrillation, a greater risk of infective endocarditis, congestive heart failure, and increased risk of sudden death. 
     Co-owned U.S. Pat. No. 5,989,284 to Laufer discloses a method of treating primary mitral value regurgitation by applying thermal energy to shorten the chordae. The method of Laufer involves insertion of a catheter into the ventricle of the heart, and placing the tip of the catheter in contact with the chordae. Shortening of the chordae can prevent prolapse of the atrioventricular valve cusps. 
     The chordae of the human heart are composed predominantly of tightly coiled strands of collagen. Application of heat to the chordae, raising the temperature of the tissue to about 50-55° C., causes the collagen strands to uncoil and straighten. Upon cooling the collagen resumes its tightly coiled shape, however, the collagen strands tend to entangle with one another, causing the total volume of the collagen, and thus the chordae, to shrink. Shrinkage of the chordae can be an effective treatment of primary mitral regurgitation and the related problem of tricuspid valve regurgitation. Likewise, heating the cusps or the annulus, which also contain collagen, to about 50-55° C., causes the collagen therein and the cusps or annulus to shrink in size and length. 
     The present invention provides catheter devices for shrinkage of tissue, such as the chordae, cusps or annulus of valves of the human heart and other tissues, such as the esophagus in the area of the sphincter or the female urethra below the bladder. Heat is applied to the target tissue via a heat transfer means on the catheter tip. The method of Laufer is a minimally invasive means of treating mitral regurgitation, however, appropriate placement of the catheter tip, and keeping it in place can be difficult, particularly in a moving organ, such as the heart. 
     In some applications, it is possible to visualize the tissue during laser treatment by means of an endoscope. This is not possible in a beating heart, due to the opaque nature of blood. In addition, the chordae are difficult to visualize by ultrasonic or x-ray techniques, thus, application of energy to the chordae, as in the method of Laufer, must be performed “blind.” A similar problem exists in treatments of female stress incontinence (FSI) involving thermal shrinkage of the tissue surrounding the urethra below the bladder. The small diameter of the urethra (about 1.5 to 5 millimeters) makes endoscopic viewing difficult. It would also be beneficial to shrink tissues such as the esophagus in the area of the sphincter to treat gastro-esophageal reflux disease (GERD). 
     It would be desirable to be able to shrink the chordae tendineae of the heart and other tissues in a minimally invasive, non-surgical catheterization procedure that would allow precise and stable placement and application of energy to the tissues. It would also be desirable to provide a treatment that could be rendered in a few minutes in a hospital cardiac catheterization laboratory or outpatient department or an outpatient surgical center, with little recuperation time. 
     SUMMARY OF THE INVENTION 
     A catheter device suitable for shrinking chordae tendineae of the human heart is provided with an energy conduit (e.g., an optical fiber, electrical conducting cable, or other similar energy transmitting device) and a positioner device that facilitates the delivery of thermal energy to a predetermined region of the chordae tendineae. 
     In a preferred embodiment, a catheter containing an optical fiber, having a distal end portion encompassing a directional energy emitting device within an asymmetrically-shaped balloon, positions the energy conduit and directionally delivers energy to tissues. The asymmetric shape of the balloon allows an operator to precisely determine the orientation of the device within the tissue using ultrasound or x-ray imaging, for example. The distal end of the catheter is closed and has a blunt shape. The distal end portion of the catheter within the balloon contains an aperture that admits inflation fluid into the balloon, and directs the energy emission from optical fiber through only one portion of the asymmetric balloon. Thus, by imaging the inflated balloon within the tissue, the operator can determine the direction of laser energy emission. 
     In another embodiment of the present invention a fiber optic cable or other thermal energy delivery device is contained within a tubular sheath that is open at its distal end, such that laser or other thermal energy can be emitted by the cable through the distal opening of the sheath. Also present within the sheath is a flexible metal positioner and stabilizer rod, having a hook-shaped distal end portion and a blunt, atraumatic distal end. The blunt end of the flexible metal positioner and stabilizer rod can be in the form of a ball or other similar form, which will tend to slide off, rather than penetrate tissue when the end of the rod comes into contact with the tissue. 
     The hooked distal end portion of the rod is helicoid, i.e., having a configuration that approximates that of a helical coil. The length of the distal end portion is approximately 3 to 6 times the radius of curvature of the coil, i.e., the end portion comprises roughly one half to one loop of the helical coil. Both the cable and the rod are independently slidably moveable within the sheath. The distal end of the fiber optic cable can be retracted into or extended out of the distal opening of the sheath, and, independent of the cable, the hooked distal end portion of the flexible rod can be withdrawn into the sheath or extended therefrom. 
     The flexible metal rod can be preferably composed of a superelastic shape-memory alloy such as nitinol, which has been previously formed into its hooked shape by bending the distal end portion of the rod into a helical-coil shape and heat-treating the bent portion of the rod at a temperature of about 300° C. to 800° C. to fix the shape. When the distal end portion of the rod is retained within the sheath, the end portion of the rod straightens due to pressure from the relatively more rigid sheath. When substantially extended from the distal opening of the sheath, the flexible rod returns to its helical-coil/hooked shape. The distal end portion of the rod can be repeatedly coiled and uncoiled by extending the end portion out of or into the sheath, respectively, due to the shape-memory properties of the superelastic alloy. 
     The sheath portion of the catheter device defines one or more lumens in which the energy conducting cable and flexible rod are disposed. In a preferred embodiment of the invention, the flexible sheath defines two lumens, the energy conducting cable being situated in a first lumen and the flexible rod being situated in a second lumen. In addition, there can be other lumens within the sheath, for example, there can a lumen for a guide wire, commonly used to position a catheter within a specific area of the anatomy, or a lumen for delivery to, or withdrawal of fluids from, the irradiation site. Alternatively, the catheter device of the present invention can have a sheath with a single lumen, wherein the rod and cable are positioned side by side in the same lumen, through which fluid can also be infused or withdrawn. 
     The proximal end of the flexible sheath can be attached to a handpiece to provide the operator of the device a method of controlling the position and orientation of the device. The handpiece can include a mechanism or mechanisms for manipulating either the flexible rod, the energy cable, the sheath or any combination thereof. 
     The energy conducting cable extends throughout the whole length of the device, generally exiting the device at the proximal end of the handpiece and extending further to a coupler at the proximal end of the cable, adapted for connection to an energy source. When the energy source is a laser generator, the coupler is an optical coupler, and the cable comprises at least one, and preferably several optical fibers. A plurality of optical fibers can be bound together in a sleeve or wrapped in a plastic film, such as shrink-wrap, to protect the fibers and create a single optical cable. 
     Alternatively, the cable can comprise one or more insulated wires, adapted at their proximal end for connection to an electrical power or radiofrequency (RF) energy source. The distal end of each wire, located in close proximity to the distal opening of the sheath, is adapted for connection to a variety of energy emitting devices, such as electrical resistive heating loops, ultrasonic generators, microwave generators, RF electrodes, and the like. The individual wires are preferably bound together as described for the optical cable above. 
     Optionally, a slidable control button or lever, which can be engaged by the operator&#39;s thumb, is disposed within a slide channel on the exterior of the handpiece. The portion of the button which extends through the slide is attached to a metal sleeve which, in turn, is attached to and surrounds the energy conducting cable. When the button is advanced a predetermined distance, an audible “click” can be created by an optional ratchet mechanism, and the energy cable is extended a like distance out of the distal end of the sheath in which it is disposed. A similar mechanism can be used to control the extension and retraction of the flexible metal rod to deploy the hooked distal end of the rod or to manipulate the position of the sheath relative to the energy cable or rod. Alternatively, the rod, sheath and/or energy cable can be manipulated by a rotatable knob attached to a shaft, which shaft is operably attached to the energy cable, the sheath, or the rod in a manner such that the cable, rod or sheath can be slidably moved distally or proximally by turning the knob. In an alternative embodiment, the operator can optionally deploy the flexible metal rod or cable by grasping the proximal end of the rod or cable and manually sliding the rod or cable forward or backward a predetermined distance. 
     In use, an operator positions the distal end of the sheath within a ventricle of the heart, in close proximity to a papillary muscle, with both the distal end portion of the rod and the distal end of the cable substantially retracted into the sheath. The operator can guide the device into its desired position by inserting it over an earlier placed guide wire, can thread the device through a tubular catheter that has been pre-positioned in the heart, by articulating the distal end portion of the sheath or by any other acceptable method known in the medical art. After proper positioning, the distal end portion of the rod is then slid forward to gradually extend the end portion of the rod from the distal end of the sheath. As the distal end portion of the rod becomes less constrained, it gradually resumes its curved shape, and can thus encircle the papillary muscle and then be manipulated up to encircle the chordae tendineae that are attached to the papillary muscle. 
     After the rod has encircled the chordae, the operator extends the distal end of the energy cable out of the distal opening of the sheath, placing the distal end of the cable in close proximity to, or in contact with the chordae. The hooked end of the rod acts as a stabilizer for the distal end of the catheter device. Thermal energy, in the form of coherent light (laser), ultrasound, microwave, RF energy, or heat generated from an electrical resistive heating coil is supplied to the chordae, by the energy cable, in a quantity sufficient to raise the temperature of the collagen in the chordae to about 50 to 55° C., causing the collagen strands to uncoil. When the emission of energy is ceased, the chordae shrink upon cooling of the collagen, thus tightening the chordae and preventing further prolapse. After the thermal irradiation of the chordae has ceased, the rod and cable can be withdrawn fully, or partially into the sheath, and the catheter device can be repositioned above or below the first treated area of the chordae for further treatment or removed entirely. 
     In a preferred embodiment, the distal end of the cable can be encased in an asymmetric, energy-transmissive balloon attached to the distal end of a catheter. For treatment of atrioventricular valve malfunction, such as primary mitral valve regurgitation, the balloon-tipped catheter device can be moved, with the balloon deflated, into position within the left ventricle using either a conventional guide wire or a guiding catheter, which has been previously inserted into an artery, such as the femoral artery, and advanced through the aorta and the aortic valve into the left ventricle, as is known in the art. The distal end portion of the asymmetric balloon-tipped catheter can be formed into a fixed angle, or the catheter can contain a control element for changing the angle of the distal end portion of the catheter to facilitate precise placement of the asymmetric balloon near or in contact with the chordae. 
     Likewise, the distal end portion of the device can be positioned near or in contact with the cusps or the annulus of the valve, and the procedure can be carried-out, as described above, to shrink the same. 
     An optical fiber extends throughout the length of the catheter and is adapted at its proximal end for connection to a source of laser light. The distal end of the optical fiber is positioned opposite the aperture in the distal end portion of the catheter, so that laser light emission from the optical fiber is directed out of an aperture at an angle in the range of about 60 to about 100 degrees from the axis of the fiber. The balloon surrounding the distal end portion of the catheter is asymmetric in shape, having the side of the balloon facing the aperture extending further from the catheter than the opposite side of the balloon. When the balloon is inflated with a fluid that appears opaque under ultrasound or x-ray imaging, the orientation of the balloon within the heart chamber is readily determined. Thus, an image showing the orientation of the greater inflated side of the balloon also indicates the direction of energy emission to the operator. 
     The balloon catheter can encompass lumens for acceptance of a guide wire, and/or a hooked stabilizing rod such as is described hereinabove. The catheter can also include thermocouples to measure the temperature of the tissue being irradiated and/or the inflation fluid within the balloon. 
     The proximal end of the balloon catheter preferably comprises a handpiece adapted for delivering inflation fluid through the catheter and into the balloon through the aperture in the distal end portion of the catheter The handpiece can also contain a mechanism for controlling the angle of the distal end portion of the catheter for more precise positioning of the balloon within the tissue. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, FIG. 1 is a schematic of the human heart illustrating the position and morphology of the atrioventricular valves, the chordae tendineae and the papillary muscles; 
     FIG. 2 is a schematic external view of a preferred embodiment of the catheter device of the present invention, operably connected to an energy source such as a laser energy or electrical current source; 
     FIG. 3 is a cross-sectional detail of the handpiece of an embodiment of the device of FIG. 2 showing a mechanism for moving the flexible sheath relative to the energy conducting cable; 
     FIG. 4 is an external view of the distal end portion of the device of FIG. 2, shown with the hooked distal end portion of the flexible metal rod encircling a papillary muscle within a ventricle of a human heart; 
     FIG. 5 is an external view of the distal end portion of the device of FIG. 2, shown with the hooked distal end portion of the flexible metal rod encircling chordae within a ventricle of a human heart, and with the distal end portion of the energy conducting cable extended out of the distal opening of the flexible sheath, and in close proximity to the chordae; 
     FIG. 6 is a partial cross-sectional end view of a dual lumen embodiment of the catheter device showing a fiber optic cable in a first lumen and a flexible metal rod in the second lumen; 
     FIG. 7 is a partial cross-sectional view of the device of FIG. 6 showing the distal end portions of the optical fibers extended out of the distal opening of the first lumen and the hooked end portion of the flexible metal rod deployed outside of the distal opening of the second lumen; 
     FIG. 8 is a partial, expanded view of the distal end of a preferred embodiment of the device of FIG. 6 with the blunt end of the flexible metal rod positioned just distal to the opening of the second lumen and with the opening of the first lumen having a substantially linear, slit-like shape, such that the end portions of the individual optical fibers form a substantially linear, brush-like array when they are extended out of the distal opening of the first lumen; 
     FIG. 9 is a partial, expanded view of the distal end of a preferred embodiment of the device of FIG. 6 with the blunt end of the flexible metal rod positioned just distal to the opening of the second lumen and with the opening of the first lumen having a substantially V-shape, such that the end portions of the individual optical fibers form a substantially V-shaped array when they are extended out of the distal opening of the first lumen; 
     FIG. 10 is a partial, expanded view of the distal end of a preferred embodiment of the device of FIG. 6 with the blunt end of the flexible metal rod positioned just distal to the opening of the second lumen and with the opening of the first lumen having a substantially curved slit-shape, such that the end portions of the individual optical fibers form a substantially curved array when they are extended out of the distal opening of the first lumen; 
     FIG. 11 is a partial, cross-sectional view of the distal end of a preferred embodiment of the device of FIG. 6 having a control wire attached to the fiber optic cable, which allows the operator to slide the fiber optic cable distally and proximally within the first lumen of the sheath in order to project the optical fibers in the end portion of the cable through the distal opening of the lumen; 
     FIG. 12 is a cross sectional detail of a preferred embodiment of a handpiece useful in combination with the device of FIG. 11 having a reel mechanism for moving a control wire; 
     FIG. 13 is a cross sectional detail of a preferred embodiment of the first lumen of the device of FIG. 11 having an obturator mechanism for spreading the optical fibers of the distal end portion of the optical cable into a roughly conical array when the cable is slid distally within the lumen to project the fibers out of the distal opening of the lumen; 
     FIG. 14 is a partial external view of an alternative preferred embodiment of the first lumen of the device of FIG. 11 wherein the end portions of the optical fibers of the fiber optic cable are encased in curved flexible metal tubes, which cause the fibers to spread into a fan-like array when the end portions of the fibers are projecting out of the distal opening of the first lumen; 
     FIG. 15 is a partial, cross-sectional view of the device of FIG. 14, illustrating the disposition of the flexible metal tubes over the end portions of the optical fibers; 
     FIG. 16 is a schematic, external view of the elements of a preferred embodiment of the device of the present invention; 
     FIG. 17 is a partial, cross-sectional view of the distal end portion of an embodiment of the device of FIG. 16, which utilizes laser energy emitted at a right angle; 
     FIG. 18 is a partial, cross-sectional view of the left ventricle of a human heart and an exterior, partial view of the device of FIG. 16, positioned opposite the chordae tendineae; 
     FIG. 19 is an exterior view of an embodiment of the device of FIG. 16, positioned opposite the chordae tendineae. 
     FIG. 20 is a partial cross-sectional view of the distal end portion of a preferred embodiment of the device of FIG. 16, having a control wire attached to the catheter wall to allow manipulation of the distal end of the catheter; 
     FIG. 21 is a cross-sectional view of an embodiment of the handpiece of the devices of FIGS. 16-20; 
     FIG. 22 is a cross-sectional view of an alternative embodiment of the handpiece of the device of FIGS. 16-20; 
     FIG. 23 is a partial, external view of the distal end portion of the devices of FIGS. 16-20 positioned in the female urethra below the bladder, with the balloon deflated; 
     FIG. 24 is a partial, external view of the distal end portion of the device of FIGS. 16-20 positioned in the female urethra below the bladder, with the balloon inflated; and 
     FIG. 25 is a partial, cross-sectional view of a preferred embodiment of the device of FIG. 16 which incorporates a channel for a guide wire. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described in detail herein specific embodiments thereof, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments illustrated. 
     FIG. 1 depicts the anatomy of the human heart, illustrating the relative size and orientation of the chordae, papillary muscles and atrioventricular valves. As shown in FIG. 1, the chordae rise in a roughly conical array from the papillary muscles up to the periphery of the cusps of the atrioventricular valves. 
     As shown in FIG. 2, a source of light energy  2 , such as a laser or high energy light source, is optically coupled through an optical connector  3  to an energy conducting cable  4 , which is a fiber optic cable composed of a plurality of optical fibers  6 . Cable  4  extends through handpiece  10  and flexible sheath  12 , and is moveable therein. Control button  14  is moveably disposed within slide channel  16  in handpiece  10 , and can be extended and retracted by thumb pressure of the operator (not shown). Control button  14  extends through channel  16  and is attached to cable  4  by an adhesive or similar expedient. A ratchet mechanism (not shown) that emits an audible “click” each time control button  14  is advanced a given distance, for example, one millimeter, can be provided, if desired. 
     Sheath  12  comprises at least one lumen in which a flexible metal rod  18  and cable  4  are enclosed. Optionally, the sheath  12  can define two or more lumens, with flexible metal rod  18  enclosed in one lumen and cable  4  enclosed in another lumen. The sheath  12  can also define additional lumens, for example, a lumen for acceptance of a guide wire to facilitate placement of the device within the body, as is known in the art, or a lumen for withdrawal of fluids from, or infusion of fluids into the tissue site. The distal end portion  24  (FIG. 4) of rod  18  has a permanently hooked shape, but is elastic enough to temporarily straighten when constrained within sheath  12 , as shown in FIG.  2 . 
     Rod  18  extends through handpiece  10  and sheath  12 , and terminates at its distal end in a blunt, roughly spherical ball  20 , or any other atraumatically-shaped structure that will resist penetration of body tissues e.g., a rounded or blunt shape. Rod  18  is slidably moveable within the sheath  12 , such that a hook-shaped distal end portion of the rod (not shown) can be extended out of the distal opening of the sheath  12 . The proximal end portion of rod  18  can have markings  22  that allow an operator to determine the distance that the hooked distal end portion of rod  18  has been deployed from the distal opening of sheath  12 . 
     The flexible metal rod  18  is preferably composed of a superelastic shape memory alloy such as nitinol. The distal end portion of the rod has been preformed into a hook-shape by bending the rod into the desired shape and heat treating the bent portion at a temperature of from about 300° C. to about 800° C. for a time sufficient to fix the shape. Nitinol is a substantially 1:1 alloy of nickel and titanium. Nitinol generally has an atomic ratio of nickel to titanium in the range of about 49:51 to about 51:49. Nitinol alloys can also comprise about 0.1 to about 5% by weight of other elements such as iron, chromium and copper. 
     The distal end of sheath  12  can include a band of ultrasound-opaque and/or radio-opaque material  23 , to enable an operator to precisely determine the position of the distal end of the device when it is deployed within a patient&#39;s body using x-ray (fluoroscopic) imaging, ultrasound imaging (preferably a transesophageal echo (TEE) imaging system) or a catheter-borne ultrasound imaging device. A preferred catheter-borne ultrasound device is the AcuNav® catheter made by Accuson, Inc. of Mountain View, Calif., which is generally deployed in the right ventricle to trans-septally view the left ventricle and the papillary muscles, chordae, cusps and annulus of the mitral valve. The proximal end of flexible sheath  12  is attached to the distal end of handpiece  10  in any convenient manner, such as by an adhesive. 
     In an alternative embodiment of the device of FIG. 2, laser light source  2  can be replaced by an electrical current source and the energy conducting cable  4  is a wire cable comprising at least one electrically conductive, insulated wire (not shown). The cable  4  is adapted at its proximal end for connection to the electric current source  2  and the distal end portion of the cable comprises an energy emission source such as a radio frequency (RF) electrode, resistive heating loop, ultrasound generator, or microwave energy generator. The energy emission source  2  is operably connected to the cable  4  such that upon application of electric current to cable  4 , the energy emission source  2  is capable of delivering thermal energy to a tissue site. 
     FIG. 3 provides a partial cross-sectional view of one embodiment of handpiece  10  of the device of FIG. 2, wherein button  14  is attached to sheath  12  and provides a means of moving sheath  12  relative to energy conducting cable  4 , thus allowing the operator to expose or cover the distal end portion of cable  4  by pulling the button proximally or pushing the button distally, respectively. In this embodiment, the energy conducting cable  4  is fixedly attached to handpiece  10  at juncture  11  by an adhesive or other expedient. As seen in FIG. 3, sheath  12  can be moved relative to handpiece  10  by sliding button  14  which is attached to sheath  12  by an extension (not shown). Button  14  is disposed within a longitudinal channel  16  in handpiece  10 . When button  14  is advanced or withdrawn, an optional ratchet mechanism (not shown) emits an audible “click”. One audible “click” made by the ratchet mechanism can indicate that energy cable  4  has been advanced a chosen distance, for example 1 millimeter. Optionally, an indicator arrow on button  14  (not shown) can indicate the distance energy cable  4  has been advanced from the distal end of the sheath  12  by means of a distance scale along the length of channel  16  (not shown). 
     An alternative embodiment of the device of FIG. 3, not shown, has the button  14  fixedly attached to the energy conducting cable  4 . In this embodiment, cable  4  is freely moveable through handpiece  10  and sheath  12 , and sheath  12  is fixedly attached to handpiece  10 . When button  14  is moved forward in channel  16 , cable  4  is slid forward relative to sleeve  12 , thus affording a way of extending the distal end of cable  4  (not shown) out of the distal opening of sheath  12 . 
     FIG. 4 is a cross-sectional view of the lower portion of the left ventricle of a human heart and a portion of the distal end of the device of FIG. 2 oriented as it would be in use, just prior to final placement for thermal treatment of the chordae. As shown in FIG. 4, the hook-shaped distal end portion  24 , of flexible metal rod  18 , is positioned around a papillary muscle  26 , below the chordae  28 . The distal end portion  24  of rod  18  is deployed by an operator (not shown) by sliding the rod  18  distally relative to sheath  12 , after the distal end of the device has been properly positioned by the operator. 
     The device of FIG. 4 can be positioned in the heart by threading it through a conventional catheter  30 , which has been previously placed in proper orientation within the ventricle by methods well known in the art. The precise position and orientation of the distal end of the device can be determined by ultrasonic or x-ray imaging, if desired. The distal end portion  24  of rod  18  has a roughly helicoid, hooked shape. Distal end portion  24  of rod  18  has a radius of curvature of about 2.5 millimeters to about 30 millimeters, preferably about 5 to 15 millimeters, when unconstrained by sheath  12 . The length of distal end portion  24  of rod  18  is generally about 3 to about 6 times the radius of curvature, i.e., the end portion comprises roughly about one half loop to about one loop of a helical-coil. 
     FIG. 5 illustrates the deployment of the hooked end portion  24  of rod  18  over the chordae  28 , by withdrawing sheath  12  partially into catheter  30 . As shown, optical fibers  6  of optical cable  4  have been extended out from the distal opening of sheath  12 . 
     In FIG. 5, the distal ends of the optical fibers  6  are positioned in close proximity to, or in contact with the chordae  28 , such that the chordae  28  can be precisely heated by irradiation with laser light from optical fibers  6 . After irradiation, optical fibers  6  can be withdrawn back into sheath  12 , and the hooked end portion  24  of rod  18  can be withdrawn into sheath  12 , so that the device can be removed from the patient through catheter  30  or can be repositioned for another treatment above or below the area first treated. Rod  18  is composed of a superelastic shape memory alloy so that it is flexible, and the curved end portion  24  is sufficiently rigid and capable of substantially straightening rod  18  when it is slid proximally, relative to sheath  12  by the operator (not shown), to draw the end portion  24  of rod  18  back into the sheath  12 . 
     A partial cross-sectional view of a dual-lumen embodiment of the present invention is illustrated in FIGS. 6 and 7. In FIG. 6, flexible metal rod  18  is contained within a first lumen  32  of sheath  12 . In this illustration, the curved end portion  24  of rod  18  is substantially disposed within the relatively more rigid lumen  32  so that the end portion  24  of rod  18  becomes substantially straightened by the sheath, relative to its unconstrained hook-shape. Fiber optic cable  4 , comprising a plurality of optical fibers  6 , bound together by a casing  34 , is disposed within a second lumen  36  of sheath  12 . Casing  34  covers all but the distal end portions of optical fibers  6 . Optical fibers  6  can be projected out from distal opening  38  of lumen  36  to a distance in the range of about 3 millimeters to about 25 millimeters, preferably about 6 to about 15 millimeters. 
     In FIG. 7, the distal end portion  24  of rod  18  is shown in its unconstrained curved-shape, after being pushed out of lumen  32  of sheath  12  by an operator (not shown). In like manner, optical fibers  6  are shown deployed through opening  38  of lumen  36 , as they would be during irradiation of the chordae. 
     The distal opening  38  of lumen  36  can have any desired configuration, however, several configurations are preferred. FIGS. 8,  9 , and  10  illustrate three alternative preferred configurations of distal opening  38  of lumen  36 . As shown in FIG. 8, opening  38  can have a substantially linear configuration, so that optical fibers  6  form a linear, brush-like array when the fibers are advanced distally through the opening by the operator. FIG. 9 illustrates a substantially V-shaped opening  38 , such that the optical fibers  6  form a roughly V-shaped array when pushed through the opening by the operator. FIG. 10 shows a curved form of opening  38 . 
     A partial cross-sectional view of the distal end portion of a preferred embodiment of the dual lumen device of FIG. 6 is shown in FIG.  11 . Control wire  40  is fixedly attached near the distal end of catheter  12  by metal cleat  42 , or other expedient. Control wire  40  allows an operator to articulate the distal end portion of catheter  12  into a desired curved shape. FIG. 11 shows the distal end portions of optical fibers  6  substantially retracted into lumen  36  of catheter  12 . Control wire  40  can be made of stainless steel or a superelastic alloy such as nitinol, preferably with a diameter of about 0.005 inches to about 0.010 inches. 
     A preferred embodiment of the handpiece of dual lumen device of FIG. 11, shown in FIG. 12, has a reel mechanism  44  for moving control wire  40 . For clarity, optical cable  4  is not shown within the handpiece  10 . Reel  44  comprises a rotatable shaft  46 , extending substantially through handpiece  10 , and pivotally moveable therein, having at least one end projecting above the outer surface of handpiece  10 . Knob  48  is axially attached to the end of shaft  46  that projects above the outer surface of the handpiece  10 . The proximal end of control wire  40  is attached to shaft  46  at a point  50 , such that when an operator turns knob  48 , control wire  40  is wound around shaft  46 , thus pulling control wire  40  and causing the distal end portion of catheter  12  to be formed into a curved shape of a desired arc or angle. In this embodiment, control wire  40 , when in a completely unwound state, would return sheath  12  to its original, substantially straight shape. Alternatively, a second control wire (not shown), could be attached near the distal end of catheter  12  on the side opposite control wire  40 , so when knob  48  is turned to extend control wire  40 , the second control wire (not shown) is retracted to mechanically straighten catheter  12  by opposing the force exerted by wire  40 , as known in the art. 
     As shown in FIG. 13, the distal opening  38  of lumen  36  can contain an obturator device  52  that partially closes the opening and forces the distal end portions of optical fibers  6  to exit lumen  36  along the periphery of opening  38  to form a roughly conical array when cable  4  is moved distally relative to opening  38  of lumen  36 . Obturator  52  can be attached to the periphery of opening  38  by struts  54 . Obturator  52  can have a roughly football shape as illustrated in FIG. 13 or can be spherical, conical, pyramidal, or any other useful configuration. 
     FIGS. 14 and 15 present partial views of another preferred embodiment of the device of FIG. 6, wherein the distal end portions of optical fibers  6  are encased in curved flexible metal tubes  56 , open at their distal ends to allow laser light to be emitted from optical fibers  6  disposed therein. For purposes of clarity, the first lumen, containing the flexible metal rod, is not shown. Tubes  56  are preferably composed of a superelastic shape memory alloy, most preferably a nickel-titanium (nitinol) alloy which have been fixed in a curved shape by heat treatment as described for the flexible metal rod, above. As shown in FIG. 15, the flexible tubes  56  are disposed over the distal end portions of optical fibers  6  with distal ends of the fibers at or just proximal to the distal end of the tubes. The tubes  56  are open at both their distal and proximal ends to allow light to pass through the optical fibers and be emitted therefrom. 
     As described in the previous embodiments, the optical cable  4  is slidable within the sheath  12 , so that the distal end portions of the fibers  6 , and their attached metal tubes  56  can be retracted into and extended out of sheath  12 , or sheath  12  can be retracted exposing metal tubes  56  and optical fibers  6  disposed therein. Tubes  56  become substantially straightened when confined within sheath  12 , however, when the tubes  56  are extended out of the distal end of sheath  12 , they resume their prefabricated curved memory-shape. The tubes can be arrayed in a linear, circular or any other desired configuration. 
     The distal ends  58  of tubes  56  can optionally be beveled in the form of a syringe needle to facilitate penetration of the tubes into tissue, for example, into the esophagus in the area of the sphincter or the tissue surrounding the female urethra below the bladder. 
     In the embodiments of the present invention in which the energy conducting cable  4  is a fiber optic cable, the free distal end portions of optical fibers  6  are preferably about 3 to about 25 millimeters long, most preferably about 6 to about 15 millimeters long. Optical fibers  6  preferably are made of quartz or fused silica, and have a core diameter of about 100 to about 600 microns, preferably about 200 to about 400 microns. As shown in FIG. 6, cable  4 , comprising a plurality of optical fibers  6 , is enclosed in a casing  34 , which in this instance is a heat shrinkable film, such as polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE). Casing  34  can also be a sleeve made of PET, PTFE or any other flexible plastic material, as known in the art. The number of optical fibers contained in the cable  4  can vary from 1 to about 20, preferably from 1 to about 10. 
     Lasers which can be utilized with the above described devices include, without limitation argon, KTP, diode, Nd:YAG, Alexandrite and Holmium:YAG, the latter requiring optical fibers with a low hydroxyl or low-OH content. High intensity white light or filtered light of a desirable wavelength can also be used, as known in the art. 
     At a given position in close proximity to or in contact with the chordae tendineae, after the optical fibers have been deployed, an argon, KTP, diode, Nd:YAG, Alexandrite or other laser can be used to irradiate the tissue at an energy level of about 3 to about 30 watts for about one-half second to about 20 seconds, after which the device can be repositioned and the procedure repeated until a sufficient shrinkage or tightening of the chordae has occurred. A Holmium:YAG laser can be used, for example, by irradiating with a laser energy in the range of about 100 millijoules to about 500 millijoules per pulse at a repetition rate in the range of about 5 to 60 hertz, or at a laser energy in the range of about 500 millijoules to about 2 joules per pulse of laser energy at a repetition rate in the range of about 1 to about 30 hertz. The irradiation can be employed for a period of time in the range of about one-half second to about 20 seconds, after which the device can be repositioned and the procedure repeated. 
     The above described devices can be made of various elastic, flexible or rigid materials and in various sizes, depending upon the application. The outside diameter of sheath  12  is preferably in the range of about 1 millimeter to about 10 millimeters in diameter, more preferably in the range of about 2 to about 6 millimeters in diameter. 
     The energy conducting cable extends throughout the whole length of the device, generally exiting the device at the proximal end of the handpiece and extending further to a coupler at the proximal end of the cable, which is adapted for connection to an energy source. When the energy source is a laser generator, the coupler is an optical coupler, and the cable comprises at least one, and preferably several optical fibers. 
     Alternatively, the energy conducting cable can comprise one or more insulated wires, adapted at their proximal end for connection to an electrical power source. The distal ends of the wires, located in close proximity to the distal opening of the sheath, are adapted for connection to a variety of energy emitting devices, such as electrical resistive heating loops, ultrasonic or microwave generators, and RF electrodes. The individual wires are preferably bound together as described for the optical cable above. For example, the energy conducting cable  4  can comprise a pair of leads having a proximal end adapted for connection to an electrical power source and a distal end portion operably connected to an ultrasonic generator, such as a piezoelectric generator or a magnetostrictive generator. Alternatively, the distal end portion of the pair of leads can be operably connected to a resistive heating loop. Upon application of electric current through the leads, the energy from the ultrasonic generator or resistive heating loop heats nearby collagen-containing tissue and ultimately results in a shrinkage of that tissue. 
     In another embodiment, the energy conducting cable  4  comprises at least one insulted wire adapted at its proximal end for connection to a source of electric current, and having a distal end portion comprising a RF-electrode. Upon application of electric current to the RF-electrode, radio frequency energy is emitted from the electrode, which heats any nearby tissue, such as the chordae tendineae. 
     In use, as shown in FIGS. 4 and 5, an operator (not shown) positions the distal end of the sheath  12  within a ventricle of the heart, in close proximity to a papillary muscle, with both the distal end portion  24  of rod  18  and the distal end of cable  4  substantially retracted into sheath  12 . The operator can guide the device into its desired position by a guide wire or can thread the device through a catheter that has been pre-positioned in the heart, or by any other acceptable method known in the coronary medical art. After proper positioning of the distal end of sheath  12  within a ventricle, near the chordae  28 , the distal end portion  24  of the rod  18  is then slid forward to gradually extend the end portion of the rod from the opening at the distal end of the sheath. As the distal end portion  24  of the rod  18  becomes less constrained, it gradually resumes its prefabricated curved shape, and can thus encircle the papillary muscle  26  and then be manipulated up to encircle the chordae  28  that are attached to papillary muscle  26 . 
     After rod  18  has encircled chordae  28 , the operator extends the distal end of energy cable  4  out of the distal opening of sheath  12 , placing the distal end of cable  4  in close proximity to or in contact with chordae  28 . The curved end portion  24  of rod  18  acts as a stabilizer for the distal end of catheter  12 . Thermal energy, in the form of coherent light (laser), high intensity non-coherent or filtered light, ultrasound, microwave or RF energy, or heat generated from an electrical resistive heating coil is supplied to the chordae, through the distal end of the energy cable  4 , in a quantity sufficient to raise the temperature of the collagen in some or all of the chordae to about 50 to 55° C., causing the collagen strands to uncoil. The chordae strands shrink upon cooling of the collagen, thus tightening the cusps of the valve and preventing prolapse of the cusps into the atrium during the systole phase of the heart cycle. After the thermal irradiation of the chordae has ceased, the distal end portions of  18  and cable  4  can be withdrawn fully, or partially into the sheath  12 , and the device can be repositioned for further treatment or removed entirely. 
     As shown in FIG. 16, a particularly preferred embodiment of the device of the present invention is comprised of optical fiber  60 , which extends from a connector  62  that optically couples optical fiber  60  to a source of laser energy  64 . Optical fiber  60  extends through and is fixably attached by an adhesive or the like to handpiece  66 . Handpiece  66  contains a fluid port  68 , such as a luer lock, to introduce a fluid into the hollow body of handpiece  66 . Optical fiber  60  also extends through catheter  70 , whose proximal end is fixably attached to the distal end of handpiece  66  by an adhesive or the like. Catheter  70  is in fluid communication with hollow handpiece  66  and balloon  72 . Balloon  72  is fixably attached over the distal end portion of catheter  70 , just proximal to its distal end. Emission port  74  enables laser energy to be emitted from catheter  70  through balloon  72 , as shown by the arrows. The balloon  72  has an asymmetric shape, with the side of the balloon facing the emission port  74  being, when inflated, relatively greater in radius than the opposite side of balloon  72 . Fluid can be pumped through handpiece  66  (not shown), catheter  70 , and emission port  74  to inflate balloon  72  when it has been properly positioned for treatment. When balloon  72  is inflated with a radio or ultrasound-opaque fluid, the asymmetrical shape thereof enables the operator to ascertain the direction in which radiant energy will be emitted and to rotate and redirect the direction of emission. 
     As shown in FIG. 17, the distal end of optical fiber  60  is beveled at an angle of approximately  39  degrees to obtain total internal reflection of the light energy, which exits emission port  74  and through balloon  72  laterally at an angle of about 60 degrees to about 100 degrees, preferably about 78 degrees, from the axis of optical fiber  60 , as shown by the arrows. To provide an air environment, which is necessary to obtain total internal reflection of light energy, any vinyl cladding and buffer coat  78  are first removed from the exterior of the distal end portion of optical fiber  60 , and then capillary tube  80  is fused to the glass cladding of the distal, bared end portion of optical fiber  60 . Fusing of capillary tube  80  to optical fiber  60  can be accomplished, for example, by using a carbon dioxide laser, whose energy is absorbed by quartz or fused silica. Alternatively, capillary tube  80  can be affixed to the distal end portion of buffer coat  78  or to the glass cladding of optical fiber  60  by an adhesive or the like. 
     As depicted in FIG. 18, the device of FIG. 16 has been advanced into the left ventricle  29  through a conventional guide catheter  30 , such as made by Cook Vascular, Inc. of Leechburg, Pa., whose distal end portion can be permanently bent at a desired angle, such as 30 degrees, as shown. Any other angle can be used, from about 10 degrees to about 60 degrees, preferably about 20 degrees to about 50 degrees. The distal end portion of catheter  70  has likewise been formed into a permanently curved shape at an angle of about 10 degrees to about 60 degrees; preferably about 20 degrees to about 50 degrees. 
     By changing the relative positions of the bent distal end portion of guide catheter  30  and the bent distal end portion of catheter  70 , the distal end of catheter  70  can be brought near to or into contact with the chordae tendineae  28 , as well as near or into contact with the cusps or annulus of the valve. Laser energy, transmitted through optical fiber  60  (not shown) disposed within catheter  70 , is directed by total internal reflection through emission port  74 , and exits balloon  72 , as shown by the arrows. 
     FIG. 19 illustrates an embodiment of the device of the present invention, in which the distal end portion of catheter  70  can be articulated at a desired angle, from 10 degrees to about 180 degrees, preferably from about 20 degrees to 170 degrees, from outside the body. In this embodiment, the device of FIG. 16 is introduced into left ventricle  29  through guide catheter  30 , as known in the art. Catheter  70  is articulated, as shown, into an angle of about 90 degrees. Laser energy is emitted from emission port  74  and exits balloon  72 , as shown by the arrows. 
     FIG. 20 illustrates the distal end portion of a preferred embodiment of the device of FIG. 16, in which articulation wire  82  is affixed to the interior surface of catheter  70  proximal to emission port  74 . Articulation wire  82 , when retracted, forces the distal end portion of catheter  70  into a desired angle. Again, in this embodiment, when balloon  72  is inflated and laser energy is transmitted through optical fiber  60 , the laser energy exits emission port  74  and balloon  72  as shown by the arrows. 
     FIG. 21 illustrates details of handpiece  66  of the devices of FIGS. 16-20. Optical fiber  60  is fixedly attached to the proximal end of handpiece  66  by adhesive  84 . Catheter  70  is affixed to the distal end of the handpiece  66  by an adhesive. The distal end of port  68  is affixed to a bore  88  in handpiece  66  by adhesive  90 . Male luer lock  92  is affixed to the exterior surface of the proximal end of fluid port  68  by adhesive  94 , as known in the art. Alternatively, a female luer lock can be employed, if desired. 
     As seen in FIG. 22, handpiece  66  of the devices of FIGS. 16-20 contains channel  96  and track  98 , within which lever  100  is slidably disposed. The proximal end of articulation wire  82  is affixed to lever  100 . When lever  100  and attached wire  82  are retracted, the distal end portion of catheter  70  (as shown in FIGS. 19 and 20) is bent into a desired angle. Handpiece  66  contains button  102 , which indicates to the user the direction in which laser energy will be emitted. 
     FIGS. 23 and 24 illustrate the devices of FIGS. 16-20 as they would be deployed in the female urethra below the bladder for the treatment of female stress incontinence (FSI). 
     As seen in FIG. 23, the distal end portion of catheter  70  is disposed within the female urethra  104  below the bladder  106 , with balloon  72  deflated. 
     In FIG. 24, balloon  72  of the device of FIG. 23 has been inflated. Ultrasonic of X-ray imaging can be used to determine the orientation of the balloon, and thus the direction in which the laser energy will be emitted. 
     A cooling fluid, such as tap water, chilled water or saline, or a gas such as carbon dioxide, can be circulated through balloon  72  to inflate balloon  72  and cool the sensitive endothelial lining of urethra  104  in contact therewith. Cooling urethra  104  prevents damage to the urethral tissue by counteracting the thermal energy passing therethrough to heat and, ultimately, shrink the tissue underlying urethra  104 . 
     As seen in FIG. 25, the devices of FIGS. 16-19 can also be inserted into the left ventricle by means of a guidewire. In this embodiment, cannula  110 , which consists of a flexible plastic tube, preferably made of a thermally resistant plastic, such as a polyimide, is fixedly attached to catheter  70  at entry opening  114  in catheter  70 , passes behind optical fiber  60  and the non-energy emitting side of capillary tube  80 , and is fixedly attached to distal opening  116  of catheter  70 . Thus, cannula  110  creates a passageway through the distal end portion of catheter  70 , through which guidewire  112  can extend, as disclosed in co-owned U.S. Pat. No. 4,773,413 to Hussein et al., the relevant portions of which are incorporated herein by reference. Cannula  110  and guidewire  112  pass behind optical fiber  60  and capillary tube  80  to avoid being heated and damaged by laser energy emitted from the energy emitting surface of capillary tube  80  through laser energy emission port  74 , as shown by the arrows. Likewise, cannula  110 , creating a pathway for guidewire  112 , can be incorporated in any of the devices described herein. Optionally, the distal end of catheter  70  can comprise an ultrasound—or radio opaque band to further aid in determining the position of catheter  70  within a patient&#39;s body. 
     Lasers which can be used in conjunction with optical fibers of the devices of the present invention include, but are not limited to, argon KTP, pulsed dye, diode, Nd:YAG, Alexandrite, Holmium:YAG and others. Of these, Holmium:YAG energy requires the use of low-OH optical fibers. Fluids that can be used to inflate the balloon of the devices of the present invention, for use with the sources of energy listed below, include, but are not limited to, the following: for a Holmium:YAG laser, a non-aqueous fluid, such as a perfluorocarbon, carbon dioxide or nitrogen gas can be utilized; for Argon, KTP, pulsed dye, diode, or Nd:YAG lasers, saline, an aqueous radio-opaque fluid, such as Hexabrix®, or an aqueous ultrasound-opaque fluid, such as Optison®, both available from Mallinckrodt, Inc. of St. Louis, Mo., carbon dioxide or nitrogen gas can be used. 
     Elastic, compliant materials that can be used for the balloon include, but are not limited to, latex and silicone. Plastic, non-complaint films that can be used for the balloon include, but are not limited to, polyurethane, polyethylene, polyisoprene, polyethylene terephthalate or PET, nylon and Teflon, as known in the art. Of these, silicone and polyethylene are preferred. 
     It can also be desirable to shrink the cusps or the annulus of an incompetent (loose) heart valve, using the devices of the present invention. In such application the device is positioned near or in contact with the cusps or within the annulus of the valve and thermal energy is applied thereto. 
     In shrinking the chordae tendineae, the cusps, or the annulus of a heart valve, it can be desirable to apply laser, electrical, RF, microwave, ultrasound or other energy when the chordae, cusps, or annulus are relaxed at an appropriate time during the cardiac cycle, during diastole, systole or such other time as can be desired. 
     Human chordae have a similar form and collagen content to that of the pig chordae. Pig hearts were utilized in the following examples as a model for a human heart. 
     EXAMPLE 1 
     Shortening of Stressed Chordae Tendineae of Pig Hearts by Application of Laser Energy 
     Porcine (pig) chordae tendineae were placed under water at about 18° C. The length of the chordae were measured with the chordae under a stress of about 0.2 lb. Three pulses of Holmium:YAG laser energy were applied to the chordae over a period of one-half second at the energies described in Table 1, below. After irradiation, the lengths the chordae were again measured with the chordae not under stress. The percentage of shrinkage of the stressed chordae are provided in Table 1. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Mean Shrinkage of Pig Heart Chordae Tendineae After Irradiation 
               
               
                 With Laser Energy, with the Chordae Tendineae Under Stress. 
               
             
          
           
               
                   
                 Energy Delivered 
                 Percentage Shrinkage 
               
               
                   
                   
               
               
                   
                 200 mj/pulse × 3 pulses = 0.6 joules 
                  7% 
               
               
                   
                 800 mj/pulse × 3 pulses = 2.4 joules 
                 11% 
               
               
                   
                   
               
             
          
         
       
     
     EXAMPLE 2 
     Shortening of Relaxed Chordae Tendineae of Pig Hearts by Application of Laser Energy 
     Porcine (pig) chordae tendineae were placed under water at 18° C. The length of the chordae were measured with the chordae relaxed. Three pulses of Holmium:YAG laser energy were applied to the chordae over a period of one-half second at the energies described in Table 2, below. After irradiation, the lengths the chordae were again measured with the chordae relaxed. The percentage of shrinkage of the relaxed chordae are provided in Table 2. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Mean Shrinkage of Pig Heart Chordae Tendineae After Irradiation 
               
               
                 With Laser Energy, with the Chordae Tendineae Relaxed. 
               
             
          
           
               
                   
                 Energy Delivered 
                 Percentage Shrinkage 
               
               
                   
                   
               
               
                   
                 200 mj/pulse × 3 pulses = 1.2 joules 
                 24% 
               
               
                   
                 800 mj/pulse × 3 pulses = 4.8 joules 
                 31% 
               
               
                   
                   
               
             
          
         
       
     
     As is demonstrated in Example 1, Table 1, shrinkage of pig heart chordae of about 7% to about 11% was effected by laser treatment when the chordae were under stress during irradiation. Similar shrinkage is expected for human chordae, since they have a similar collagen content to the chordae of the pig. In Example 2, laser treatment of pig heart chordae with the chordae relaxed resulted in shrinkage of between about 24% to 31%. as shown in Table 2. This greater shrinkage effect can be achieved in practice by synchronizing the emission of the laser energy with the patient&#39;s ECG so as to irradiate the chordae during diastole, as described in co-owned U.S. Pat. No. 4,488,975 to Shturman et al., the relevant portions of which are incorporated herein by reference. 
     In use, the AcuNav® ultrasound catheter (Accuson, Inc. of Mountain View, Calif.) can be employed in “image” mode to maneuver the energy emitting tip of the catheter near to or in contact with the chordae of the mitral valve. Then, before emission of thermal energy, the AcuNav® catheter can be employed in “color doppler” mode, and blood can be seen spurting from the mitral valve during the heart&#39;s compression as bright red against a blue/purple field. Energy can be emitted at one or a series of points along the chordae, until the spurting of blood through the valve ceases. If, after the emission of thermal energy, spurting of blood continues, the energy emitting tip of the catheter can be moved near or into contact with the cusps or annulus of the valve, and thermal energy can be applied thereto to shrink the same. 
     Numerous variations and modifications of the embodiments described above can be effected without departing from the spirit and scope of the novel features of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.