DETAILED DESCRIPTION

[0040] A Basic Shaping Device:

[0041] The shape of a normal heart is of particular interest as the shape dramatically affects the way that the blood is pumped. The left ventricle, which is the primary pumping chamber, is somewhat conical or apical in shape. The left ventricle is longer (long axis longest portion from aortic valve to apex) than it is wide (short axis widest portion from ventricle wall to septum) and descends from a base with a decreasing cross-sectional circumference to a point or apex. The left ventricle is further defined by a lateral and posterior ventricle wall and a septum that extends between the auricles and the ventricles.

[0042] Pumping of blood from the left ventricle is accomplished by two types of motion. One of these motions is a simple squeezing motion that occurs between the lateral wall and the septum. The squeezing motion occurs as a result of a thickening of the muscle fibers in the myocardium. The squeezing motion compresses blood in the ventricle chamber and ejects blood into the body. The thickness of the muscle fibers changes as the ventricle contracts. The change in thickness may easily be seen and/or routinely measured by echocardiogram and other techniques.

[0043] The other type of ventricular motion is a twisting or writhing motion. The twisting or writhing motion may begin at the apex and rise toward the base of the ventricle. The rising writhing motion occurs because the heart muscle fibers run in a circular or spiral direction around the heart. When these fibers constrict, they cause the heart to twist initially at the small area of the apex. The twisting, however, progressively and ultimately moves to the wide area of the base. The squeezing and twisting motions are equally important, as they are each responsible for moving approximately one-half of the blood pumped.

[0044] Turning now to FIG. 1 , shaping device 200 may be used to allow the left ventricle to be reconstructed back to a pre-enlarged operating condition. When a surgeon uses shaping device 200 as a guide in reconstructing the left ventricle, the reconstructed heart may be formed closer to the size and shape of the pre-enlarged heart. Consequently, the heart may perform better post-operatively than with typical conventional enlarging methods. As shown in FIG. 1 , shaping device 200 may generally be conical or “tear drop” in shape. The length “L” of shaping device 200 may vary with each patient and, typically, is a function of the volume deemed appropriate for the patient after the ventricle has been restored. Depending on the patient, the length “L” may be range from about 3 inches to about 4 inches to generally match the length of the pre-enlarged left ventricle. A surgeon may select the appropriate volume for the shaping device by estimating the volume of the pre-enlarged left ventricle. The appropriate volume of the pre-enlarged left ventricle for a patient may be estimated. Generally, the volume of the pre-enlarged left ventricle is estimated to be about 50 cc per square meter to about 70 cc per square meter of body surface area. The body surface area may be estimated according to the following formula, as is generally known in the art:

BSA=0.001*71.84w ⁰⁴²⁸ *h ⁰⁷²⁵ (1)

[0045] Where: BSA=body surface area;

[0046] w=body weight in kilograms; and

[0047] h=body height in centimeters.

[0048] 1 The shaping device may be of a shape such that when the surgeon inserts the shaping device into the left ventricle, the surgeon can use the shaping device to remodel the left ventricle into the “appropriate shape and volume” for a patient. In other words, the shaping device may be of a shape similar to the shape of the left ventricle cavity. As described herein, other aspects of a shaping device may allow a surgeon to model the left ventricle without the shaping device actually being the shape of the left ventricle. In one embodiment, shaping device 200 may be a generally conical shaped object composed of portions of spherical elements having different radii. Other embodiments may include shapes such as, but not limited to, “pear” shape, elliptical, and “tear drop” shape.

[0049] In some embodiments, such as illustrated in FIG. 2 , the shaping device may be inflatable balloon 201 . Balloon 201 may have a thickness in the range of about 0.002 inches to about 0.08 inches (e.g., about 0.03 inches). Balloon 201 may have a thickness of less than about 0.08 inches. A distal end of filler tube 208 may be coupled to point 207 along the exterior surface of balloon 201 . For instance, point 207 may be located approximately ⅓ along a length of balloon 201 , as illustrated in FIG. 2 . In other embodiments, filler tube 208 may be coupled to balloon 201 at vertex 206 or another suitable location along a length of balloon 201 . Filler tube 208 may be made of materials commonly used in the art (e.g., PVC or other biocompatible materials).

[0050] A proximal end of filler tube 208 may be connected to fluid reservoir 210 . In an embodiment, fluid reservoir 210 is a syringe. Fluid reservoir may be used to provide a pre-specified amount of fluid to balloon 201 through filler tube 208 . For example, a syringe may inject a pre-specified amount of fluid into balloon 201 . In some embodiments, a fluid control device 212 (e.g., a stopcock) may be coupled to the distal end of filler tube 208 . The injection of fluid through filler tube 208 may inflate balloon 201 to an inflated condition, as illustrated in FIG. 2 . Once inflated, the fluid inside the shaping device may be inhibited from escaping by locking fluid control device 212 . Locking fluid control device 212 may allow balloon 201 to stay inflated with the proper volume, shape, and contour during a reconstruction procedure.

[0051] The fluid pressure inside balloon 201 may be monitored by a pressure transducer (e.g., a piezoelectric transducer). The pressure transducer may be coupled to filler tube 208 with a y-connection. One lead of the y-connection may be coupled to a pressure monitor and the other lead may be coupled to the fluid source. Alternatively, the pressure monitor may be coupled to a three-way stopcock that would monitor the pressure on the filler tube side of the three-way stopcock.

[0052] The fluid used to fill balloon 201 may be any one of a number of fluids such as, but not limited to, saline solution or distilled water. Some embodiments may use a sealed balloon containing a silicone gel, such as a liquid methyl silicone resin, capable of being vulcanized blended with a dimethyl silicone fluid. Such gels are available from Applied Silicon, Inc. (Ventura, California). An embodiment using a sealed balloon may not need an external fluid reservoir such as fluid reservoir 210 .

[0053] Balloon 201 may be conventionally formed on a mandrel. The mandrel may have dimensions corresponding to the shape, contour, and size of the shaping device. As is known in the art, the mandrel can be made of metal, glass, or a hardened gelatin. To form balloon 201 , the mandrel may be dipped into a polymer solution that leaves a thin polymer coating on the mandrel surface. After the polymer has cured, balloon 201 may be removed by peeling the thin coating off the mandrel or by flushing mandrel material out of the shaping device.

[0054] Shaping Device—Other Embodiments:

[0055] The shaping device may be made out of a variety of materials in a number of configurations creating a number of embodiments. In an embodiment, if the shaping device is molded from a thermoplastic polymer such as PVC, polyethylene, or a similar material, the balloon may be “non-expandable” when inflated. Once the thermoplastic polymer balloon is inflated, balloon 201 will not significantly expand beyond the original shape. To illustrate, several shaping devices might have volumes ranging from about 100 cc to about 150 cc at 10 cc increments. If a surgeon predetermines that a patient's pre-enlarged left ventricle was 128 cc, then the surgeon might select a non-expandable balloon having a volume of 130 cc. A surgeon may also request a custom non-expandable balloon with a volume specifically sized for an individual patient.

[0056] In other embodiments, if balloon 201 is made from an elastomeric material, the balloon may significantly expand. Such elastomeric materials may include latex, polyurethane, silicone, and other elastomers sold under the trade names KRATON™ (Shell Chemical, New York, N.Y. or KRATON Polymers, Houston, Tex.), C-FLEX® (Concept Polymer, Largo, Fla.) and SANTOPRENE® (Monsanto, St. Louis, Mo.). Once the balloon is substantially inflated, the influx of additional fluid causes additional expansion of the balloon. In this embodiment, a surgeon may simply inflate the balloon to a specific volume. The original shape of the balloon may be maintained during this expansion by selectively thickening the walls of the balloon.

[0057] FIG. 3 depicts a section view of an embodiment showing thickened walls of “expandable” balloon 220 . An insertion or distal end 222 of balloon 220 may have walls at a maximum thickness. From the line A-A, the wall thickness progressively decreases to vertex 224 at point G. In some embodiments, vertex 224 connects to filler tube 208 . The wall thickness may depend on the expansion range of the balloon. For example, for an expansion of about 100 cc to about 150 cc, the thickness of the balloon would vary from about 0.01 inches at a thin end to about 0.05 inches at a thick end. Thus, the size or volume of balloon 220 may be controlled by controlling the amount and pressure of the fluid injected into the balloon.

[0058] A shaping device may not be limited to polymeric balloon embodiments. FIG. 4 depicts shaping device 280 made from a wire skeleton or frame. The wire frame may be made from surgical grade stainless steel, titanium, tantalum, and/or nitinol, which is a commercially available nickel-titanium alloy material that has shape memory and is superelastic. Nitinol medical products are available from AMF of Reuilly, France, and Flexmedics Corp., of White Bear Lake, Minn.

[0059] Shaping device 280 , depicted in FIG. 4 , is in an expanded condition. Running through the center of shaping device 280 is main shaft 282 . Main shaft 282 may have distal end 284 and proximal end 286 . At distal end 284 may be joint 288 . Coupled to joint 288 may be a series of back ribs 290 a though 290 h (only back ribs 290 a through 290 e are visible in FIG. 4 ). Back ribs 290 a through 290 h may be connected to front ribs 292 a - 292 h by hinges 294 a though 294 h (only front ribs 292 a - 292 e and hinges 294 a - 294 e are visible in FIG. 4 ). The proximal end of front ribs 292 a through 292 e may be connected to collar 296 through a series of hinges radially spaced around the collar. The use of hinges around collar 296 may encourage front ribs 292 a - 292 h to form a convex angle with respect to shaft 282 at the collar.

[0060] FIG. 5 depicts shaping device 280 in a collapsed position. In a collapsed position, back ribs 290 a - 290 h and front ribs 292 a - 292 h surround shaft 282 , as illustrated in FIG. 5 . FIG. 6 depicts a section view cut transversely through shaft 282 and the front ribs 292 a - 292 h . In operation, once shaping device 280 is inserted into the left ventricle, a surgeon may slide collar 296 along shaft 282 towards distal end 284 . The force exerted on collar 296 may cause the ribs to buckle radially outward, as illustrated in FIG. 4 . Eventually, the front ribs 292 a - 292 h will bend under the applied force. Because the front ribs 292 a - 292 h are under stress, they may tend to push collar 296 towards proximal end 286 . Lock 294 may inhibit any movement towards proximal end 286 . Thus, collar 296 may be held firmly in place along shaft 282 by front ribs 292 a - 292 h exerting a force through collar 296 to lock 294 . Lock 294 may be spring activated and designed such that collar 296 may easily slide over the lock when moving from proximal end 286 to distal end 288 . When a surgeon is ready to remove shaping device 280 , the surgeon may collapse the shaping device by pressing down on lock 294 , which allows collar 296 to slide past the lock towards proximal end 286 .

[0061] In certain embodiments, the shaping device may be used as a general guide for a surgeon. Thus, the shaping device may not need to have the same shape and volume as the appropriate left ventricle. The shaping device may have a differing shape that is used as a guide so that a surgeon can reconstruct the patients ventricle to the size and shape of the appropriate left ventricle. FIG. 7 depicts such an embodiment. In the embodiment of FIG. 7 , shaping device 300 has cone shaped member 302 and dome shaped member 304 . Cone shaped member 302 may be connected to dome-shaped member 304 by central mandrel 306 . FIG. 8 depicts a cross-sectional view of shaping device 300 depicted in FIG. 7 . Cone shaped member 302 may be approximately the same size and shape as the apex portion of shaping device 200 , depicted in FIG. 1 . Additionally, dome-shaped member 304 is approximately the same size and shape as the upper portion of shaping device 200 . Thus, cone shaped member 302 and dome-shaped member 304 may have substantially similar sizes and shapes as the corresponding apex portions and upper portions of the left ventricle of the heart. The overall length of shaping device 300 may be about the same length as shaping device 200 . Thus, when inserted into the left ventricle during a surgical procedure, shaping device 300 may be used as a guide so that the surgeon can reconstruct the patient's left ventricle to be the same size and shape as the appropriate left ventricle. Shaping device 300 may be made of a semi-rigid material (e.g., plastic). The shaping device 300 may also be made from a flexible material such as, but not limited to, soft plastic, silicone, or rubber.

[0062] FIG. 9 depicts an embodiment of shaping device 400 , which may be used as a guide to shape a patient's left ventricle. In FIG. 9 , shaping device 400 may be an expandable device, such as shaping device 200 , or a solid device, such as shaping device 300 . A variety of shape possibilities exist for a shaping device. An expandable device may expand to a predetermined shape that may be substantially similar in shape to an appropriate left ventricle or may be a different shape than the appropriate left ventricle. A shaping device, either expandable or solid, of substantially similar shape and size as the appropriate left ventricle may be used as a pattern for reconstruction of the left ventricle. In some embodiments, a shaping device of a different shape from the appropriate left ventricle may be used as either a pattern or a guide for reconstructing the left ventricle. One example of another embodiment of a shape for a shaping device is depicted in FIG. 10 . Shaping devices of various shapes and sizes may have varying wall thickness, cross-sections, and/or other dimensions as described herein.

[0063] A Shaping Device with Valve Protrusions:

[0064] Certain embodiments may also include a mechanism that holds on to attachments that fit into valve openings of the patient's heart. In one embodiment, a shaping device may have a means for fitting attachments 320 of different sizes and angles to the shaping device, as depicted in FIG. 11 . Such a mechanism may allow a surgeon the flexibility to customize an intended shape for a particular patient. One patient may have a ventricle that the surgeon desires to reconstruct where a volume of about 120 cc is desired, with an angle from the ventricle to the aortic valve of about 130° and a mitral valve that is about 24 cm diameter. The surgeon could then select a 120 cc shaping device and combine it with an attachment that matches the intended ventricle to aortic valve angle and combines the attachment with a 24 cm attachment to fit the mitral valve. This shaping device may also have graduated markings for measuring and correcting the papillary muscles and chordae tendinae angles and lengths.

[0065] In some embodiments, the shaping device may have grooves on one side to accommodate the papillary muscles and the chordae tendinae. This shaping device may also have the valve protrusions integrally included or included as attachments.

[0066] One embodiment may have a shaping device with access port 322 , depicted in FIG. 12 , to allow the surgeon to access the papillary muscles and chordae tendinae with the shaping device in place. The surgeon may examine the interior of the ventricle through the access port (i.e., perform an endoscopy on the ventricle). In some embodiments, the surgeon may use a fiber optic device to perform the endoscopy. In certain embodiments, the ventricle shaping device may be in the form of a wire frame with two protuberances and with measurement markers 324 for papillary muscles and chordae tendinae, as depicted in FIG. 12 .

[0067] During operation, a surgeon may determine the size, shape, and orientation intended for reconstructing the ventricle. During the surgical procedure, the surgeon may then open the ventricle and note the extent of a scar inside the ventricle. The desired volume-shaping device may then be placed in the ventricle and the attachments placed in either both the valves, or just one valve. The surgeon may then secure the ventricle around the shaping device. The surgeon may assess the orientation of the chordae tendinae and papillary muscles to the aortic valve using the graduated measuring devices on the mandrel. The surgeon may also use a separate measuring device on the mandrel to measure the length of the papillary muscles and chordae tendinae. The surgeon may adjust the components as needed and measure the new alignment and length after the repair.

[0068] In certain embodiments, cardiac image processing computer programs may be used in combination with specific information about a patient (e.g., specific pre-operation disease state information such as, but not limited to, ventricle size, shape, and orientation data, which may be obtained through a radiological exam) to pre-operatively determine the shape and size of a shaping device specifically for that patient. Image processing computer programs may be specifically formulated for imaging the heart (e.g., programs such as those available from Chase Medical (Richardson, Tex.)). A radiological exam may employ various diagnostic imaging modalities such as, but not limited to, ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine (Nmed). Pre-operatively determining the shape and size of a shaping device based on a particular patient's criteria may allow a manufacturer to customize the shaping device for each individual patient. In some embodiments, information obtained about the shape and size of the shaping device for an individual patient may be transferred (e.g., communicated electronically) to a manufacturing center that can use the information to design and manufacture the specific shaping device for the patient. The manufacturing center may use the information in an automated manufacturing system for producing the shaping device. An automated manufacturing system may include computer programs that control and/or provide input to the manufacturing process. The produced, patient specific, shaping device may later be used in a surgical reconstruction of a ventricle for the individual patient.

[0069] In this patent, certain U.S. patents, U.S. patent applications, and other materials (e.g., articles) have been incorporated by reference. The text of such U.S. patents, U.S. patent applications, and other materials is, however, only incorporated by reference to the extent that no conflict exists between such text and the other statements and drawings set forth herein. In the event of such conflict, then any such conflicting text in such incorporated by reference U.S. patents, U.S. patent applications, and other materials is specifically not incorporated by reference in this patent.

[0070] Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.