Abstract:
A cardiac insert or implant is deployed in a patient&#39;s heart so as to reduce ventricular volume, thereby improving cardiac function. The insert or implant may be a compressive device such as a tensile member inserted into the patient&#39;s heart, and thereafter operated or deployed to bring opposite walls of a ventricle of the patient&#39;s heart into at least approximate contact with one another to thereby constrict and close off a lower portion of that ventricle. The compressive device or tensile member is insertable into the patient heart via a catheter threaded through the patient&#39;s vascular system and into the patient&#39;s heart.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a method and device for improving cardiac function, particularly where there is congestive heart failure. 
     Congestive heart failure occurs, inter alia, where there has been a heart attack or an infection. In either case, the pumping action of the heart is impaired. In another malfunction, left ventricular hypertrophy, the myocardium of the left ventricle becomes thickened to the point of interfering with effective heart contraction. 
     A surgical procedure for treating congestive heart failure, developed by a doctor in Brazil, involves removing a triangular portion of a patient&#39;s heart. In this operation, approximately one-third of the patient&#39;s left ventricular muscle is removed. The result is that the smaller heart pumps more efficiently. 
     This new technique of course requires open heart surgery, with its attendant expense and extended convalescence. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide a surgical method for treating congestive heart failure. 
     A further object of the present invention is to provide such a surgical method which is less expensive than the above-described surgical technique. 
     It is another object of the present invention to provide a surgical method for treating congestive heart failure which may be implemented through minimally invasive procedures. 
     An additional object of the present invention is to provide a device for implementing such a surgical method. 
     These and other objects of the present invention will be apparent from the drawings and descriptions herein. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to the disposition of a cardiac insert or implant in a patient&#39;s heart so as to reduce ventricular volume, thereby improving cardiac function. 
     More specifically, pursuant to one embodiment of the present invention, a method for improving cardiac function comprises inserting a compressive device into a patient in a region including the patient&#39;s heart, and thereafter operating the compressive device to bring opposite walls of a ventricle of the patient&#39;s heart into at least approximate contact with one another to thereby constrict and close off a lower portion of that ventricle. Pursuant to a feature of the present invention, the compressive device is operated to effectively close off only the lower portion of only the one ventricle. Preferably, the one ventricle is the left ventricle of the patient&#39;s heart. The left ventricle remains a single cell chamber of smaller volume. 
     In a more particular implementation of the present invention, the compressive device is inserted through a trocar sleeve or cannula which extends through a chest wall of the patient. In another particular implementation, the compressive device includes a tensile member which is inserted or introduced into the patient through a catheter with a leading end portion guided to a region of the patient&#39;s heart. More particularly, a leading end portion of the catheter is inserted into the patient&#39;s heart, the tensile member being ejected from the leading end portion of the catheter into cardiac tissues. Where the leading end portion of the catheter is inserted into the right ventricle, the tensile member is ejected through the septum of the patient&#39;s heart and the left ventricle and into a myocardial wall of the heart. Where the leading end portion of the catheter is inserted into the left ventricle, the tensile member includes a first segment ejected into or through the septum of the patient&#39;s heart and a second segment ejected through or into the myocardial wall of the left ventricle. In either case, operating of the compressive device includes exerting a tension force on the tensile member to draw the septum and the myocardial wall together. In the latter case, the two segments of the tensile member are twisted about one another to draw the septum and the myocardial wall towards one another. 
     Where the compressive device is a tensile member such as a wire or a suture (made of metal or polymeric material), it may be formed with one or more barbs, particularly at an end, for anchoring the tensile member in the cardiac tissues. 
     Where the compressive device is inserted through a trocar sleeve or cannula, the compressive device may also take the form of a tensile member such as a wire guided to a predetermined location on the myocardium of the left ventricle by a catheter inserted into a pericardial space about the patient&#39;s heart through the trocar sleeve or cannula. The operating of the compressive device includes ejecting the tensile member from the leading end portion of the catheter through a myocardial wall, a left ventricle of the patient&#39;s heart and a septum of the heart. The operating of the compressive device further includes exerting a tension force on the tensile member to draw the septum and the myocardial wall of the left ventricle together. 
     The compressive device, a tensile member in particular embodiments of the present invention, serves to reduce the volume of the left ventricle and only the left ventricle of the patient&#39;s heart. The application of the compressive device thus serves to correct certain conditions of the patient&#39;s heart in which the pumping capacity of the left ventricle has been reduced. The reduction in the volume of the left ventricle results in a higher blood pressure and thus a more effective transmission of blood especially to peripheral tissues of the patient. 
     The method of the invention contemplates an anchoring of one end of the tensile compressive member to a septum of the patient&#39;s heart and an opposite end of the tensile compressive member to a myocardial sidewall of the left ventricle. The anchoring of the tensile compressive member may be implemented by placing a flanged or barbed element of the tensile member in contact with heart tissues. The barbed element may be embedded inside myocardial tissues or caught in an external surface of the myocardium or septum. 
     In some embodiments of the present invention, the compressive member may take the form of an elongate tack ejected from a tubular member such a catheter or trocar sleeve or cannula. 
     It is apparent, therefore, that the present invention is directed in part to a method for reducing ventricular volume, wherein a catheter is inserted into a ventricle of a patient&#39;s heart, a cardiac insert or implant is deployed from a leading end portion of the catheter, and the cardiac insert or implant is disposed in the patient&#39;s heart to reduce the volume of only a left ventricle of the patient&#39;s heart. It is contemplated that the cardiac insert or implant takes the form of a tensile member such as a wire which is attached to the patient&#39;s heart. However, other forms of inserts or implants may be effective to reduce ventricular volume. 
     A surgical method in accordance with the present invention treats congestive heart failure. The method may be performed thoracoscopically which is less expensive and less traumatic to the patient than an open-heart surgical technique. The minimally invasive, intravascularly implemented procedure is even less expensive and less traumatic to the patient. The method of the invention is simple and reliable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A through 1D are partial schematic cross-sectional views of a human heart, showing successive steps in a method for reducing ventricular volume, pursuant to the present invention. 
     FIGS. 2A through 2F are partial schematic cross-sectional views of a human heart, showing successive steps in another method for reducing ventricular volume, pursuant to the present invention. 
     FIG. 3 is a partial schematic cross-sectional views of a human heart, showing a step in yet another method for reducing ventricular volume, pursuant to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As illustrated in FIG. 1A, a method for reducing ventricular volume to improve cardiac functioning includes a step of inserting a distal or leading end portion of a catheter  20  through the vascular system of a patient, and particularly through the vena cava, into the right ventricle  22  of the patient&#39;s heart  24 . The deployment of catheter  20  is carried out according to procedures that are well known in the art. For example, the catheter  20  may be introduced over a guide wire (not shown) which has been previously threaded through the venous system to the right ventricle  22 . 
     After the distal end portion of catheter  20  has been inserted through the right auricle (not shown) into the right ventricle  22 , the catheter is manipulated to place a leading end or tip  26  of catheter  20  into engagement with a lower part of a septum  28  of the patient&#39;s heart  24 , as shown in FIG. 1B. A compressive cardiac implant or insert in the form of a tensile member  30  such as a wire or a stiff suture is then forcibly ejected from the catheter  20  through septum  28 , a lower part of the patient&#39;s left ventricle  32 , and a generally left wall or myocardium region  34  of the patient&#39;s heart  24 . 
     As further illustrated in FIG. 1B, tensile member  30  is formed at a leading end with an anchor  36  in the form of a barb or flange. Anchor  36  has a structure which permits movement of the anchor in one direction through cardiac tissues and prohibits movement of the anchor in the opposite direction through the tissue. For instance, anchor  36  may be hinged to the leading end of tensile member  30  and formed with a stop for arresting rotational motion beyond a predetermined orientation relative to tensile member  20 . Prior to the ejection of tensile member  30  from catheter  20 , anchor  36  is disposed in a collapsed configuration inside catheter  20 . Anchor  36  essentially maintains this collapsed configuration during the ejection process. 
     After anchor  36  has passed through heart wall  34 , a retraction force is applied to tensile member  30  tending to draw the tensile member back in the catheter  20 . As shown in FIG. 1C, this action results in the planting of anchor  36  along the outer side of wall  34  and a drawing together of the lower parts of septum  28  and wall region  34 . Septum  28  and heart wall  34  are thus brought into at least approximate contact with one another to effectively close off a lower or apical portion of heart  24 , as illustrated in FIG.  1 C. 
     After the limited retraction of tensile member  30  and the consequent closure of the lower or apical portion of heart  24 , tensile member  30  is provided with a second anchor  38 , as shown in FIG. 1D, and severed on a side of septum  28  inside right ventricle  22 . Anchor  38  may be similar in structure to anchor  36  (but oppositely biased;) and permanently attached thereto. In that case, tensile member  30  with anchors  36  and  38  is preselected, prior to insertion in catheter  20 , to match the particular heart  24  and deployment location. More specifically, tensile member  30  and anchors  36  and  38  together define a preformed compressive cardiac implant having an interanchor spacing equal to the combined thickness of septum  28  and heart wall  34  at the intended point of deployment of the cardiac implant. The thicknesses of septum  28  and heart wall  34  may be premeasured by a CAT scan or magnetic resonance imaging or through radiographic investigation. Anchor  38  is held in a collapsed configuration by a sleeve (not shown) inside catheter  20 , thus enabling a relative motion of anchor  38  in a distal direction (relative to the operator or surgeon) during an implantation operation. 
     In an alternative structure and method of deployment, anchor  38  is permanently fixed to tensile member  30  only after the ejection of tensile member  30  through septum  28 , left ventricle  32 , and heart wall  34 . Prior to the ejection operation, anchor  38  is housed inside catheter  30  and surrounds tensile member  30 . After ejection of tensile member  30 , anchor  38  is pushed by an ancillary tubular member (not shown) into contact with the right-ventricle side of septum  28 . Anchor  38  is then secured to tensile member  30  by any suitable means. For instance, where tensile member  30  and anchor  38  are made of thermosetting resin or polymeric material, a piezoelectric crystal may be inserted into right ventricle  22  through catheter  20  to ultrasonically weld anchor  38  to tensile member  30 . Alternatively, tensile member  30  may be formed with a series of spaced beads and anchor  38  made of an elastic bio-compatible material, so that anchor  38  may be pushed over one or more of the beads and locked to tensile member in a snap-lock fit. 
     The severing of tensile member  30  on a side of anchor  38  opposite septum  28  is effectuated by any suitable means. A cutting device (not shown) may be inserted into right ventricle  22  and subsequently removed therefrom via catheter  20 . Possible kinds of cutting devices for this application have jaws (not shown) or an ultrasonically actuated blade (not shown). Alternatively, catheter  20  might be rotated about its longitudinal axis to effectuate a twisting separation of tensile member  30 . 
     As illustrated in FIG. 2A, another method for reducing ventricular volume to improve cardiac functioning of the patient&#39;s heart  24  includes a step of inserting a distal or leading end portion of a catheter  40  through the vascular system of the patient, and particularly through the aorta (not shown), into the left ventricle  32  of the heart  24 . Again, the particulars of deploying deployment catheter  40  are well known in the art. 
     After the distal end portion of catheter  40  has been inserted through the left auricle (not shown) into the left ventricle  32 , the catheter is manipulated to place a leading end or tip  42  of catheter  40  into engagement with a lower part of a septum  28  of the patient&#39;s heart  24 , as shown in FIG. 2A. A compressive cardiac implant or insert segment in the form of a tensile member or wire  44  is then forcibly ejected from the catheter  40  through septum  28 , as depicted in FIG.  2 B. Tensile member  44  is formed at a leading end with an anchor  46  in the form of a barb or flange. As discussed above with reference to anchor  36 , anchor  46  has a structure which permits movement of the anchor in one direction through cardiac tissue and prohibits movement of the anchor in the opposite direction through the tissue. Again, anchor  46  may be hinged to the leading end of tensile member  44  and formed with a stop for arresting rotational motion beyond a predetermined orientation relative to tensile member  44 . Prior to the ejection of tensile member  44  from catheter  40 , anchor  46  is disposed in a collapsed configuration inside catheter  40 . Anchor  46  essentially maintains this collapsed configuration during the ejection process. 
     After the piercing of septum  28  by tensile member  44 , catheter  40  is withdrawn slightly, as shown in FIG.  2 B. Then, catheter  40  is manipulated to place end or tip  42  into engagement with a lower part of heart wall  34 , as shown in FIG. 2C. A second compressive cardiac implant or insert segment in the form of a tensile member or wire.  48  is then forcibly ejected from the catheter  40  through heart wall  34 , as depicted in FIG.  2 C. Tensile member  48  is also formed at a leading end with an anchor  50  in the form of a barb or flange. 
     After the piercing of heart wall  34  by tensile member  48 , catheter  40  is again pulled back slightly to a position depicted in FIG.  2 D. At that juncture, catheter  40  is turned about its longitudinal axis, as indicated by an arrow  52 , to twist tensile members or wire segments  44  and  48 . Catheter  40  may be provided at its leading end with a cross-bar (not shown) to facilitate the twisting of tensile members or wire segments  44  and  48  about one another, tensile members or wire segments  44  and  48  extending on opposite sides of the cross-bar. The twisting of tensile members or wire segments  44  and  48  draws septum  28  and heart wall  34  together, as shown in FIG.  2 E. Eventually, the twisting results in severing of tensile members or wire segments  44  and  48  so that they are joined to one another by a twist knot  54 . 
     As shown in FIG. 3, a compressive cardiac implant of insert  56  in the form of a tack is ejected from a free end  58  of a tubular applicator  60  through heart wall  34 , left ventricle  32 , and septum  28 . Applicator  60  is inserted into an intrapericardial space  62  through a thoracoscopic cannula or trocar sleeve  64 . Tack  56  is formed at a leading end with an anchor  66  in the form of a barb or flange. Anchor  66  has a structure which permits movement of the anchor in one direction through cardiac tissues and prohibits movement of the anchor in the opposite direction through the tissue. 
     After the ejection of tack  56  through ventricle  32 , a tensile force is placed on tack  56  to draw the tack in a reverse direction and thereby compress the lower portion or apex of ventricle  32  between anchor  66  and the leading end of tubular applicator  60 . After the limited retraction of tack  56  and the consequent closure of the lower or apical portion of heart  24 , tack  56  is provided with a second anchor (not shown) and severed on a side of heart wall  34  inside the intrapericardial space  62 . Where this second, closure, anchor is in the form of a resilient collar and where tack  56  is provided with a series of beads (not shown), the collar may be forced over the beads in seriatim to provide a proper clamping force on the cardiac tissues at the lower end or apex of ventricle  32 , thereby bringing septum  28  and heart wall  34  into close proximity (if not actual contact) with one another and thus substantially closing the apical portion of ventricle  32 . 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are profferred by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.