Abstract:
Apparatus and methods are disclosed for performing beating heart surgery. Apparatus is disclosed comprising a cannula having a proximal end and a distal end; an aortic filter in connection with the cannula, the aortic filter having a proximal side and a distal side; a check valve in connection with the cannula, the check valve disposed on the distal side of the aortic filter; and a coronary artery filter in connection with the cannula, the coronary artery filter having a proximal end and a distal end, and the distal end of the coronary artery filter extending distally away from the distal end of the cannula. A method is disclosed comprising providing apparatus for performing beating heart surgery; deploying the apparatus in an aorta; performing a procedure on the aortic valve; and removing the apparatus from the aorta.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
   This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/256,196, filed Dec. 15, 2000, now abandoned by Richard B. Streeter for APPARATUS AND METHOD FOR REPLACING AORTIC VALVE, which patent application is hereby incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention relates to apparatus and methods for performing cardiac surgery in general, and more particularly to apparatus and methods for performing cardiac surgery while the heart is beating. 
   BACKGROUND OF THE INVENTION 
   In many cases, surgery must be performed on the heart. Under most circumstances, the heart is stopped while this surgery is performed, and the patient is kept alive during surgery through the use of a so-called “heart-lung machine”. This type of surgery is frequently referred to as “on pump” surgery. 
   However, it has been recognized that the use of a heart-lung machine can have serious deleterious effects on the patient. Therefore, interest has become widespread in conducting so-called “off pump”, or “beating heart”, coronary artery bypass surgery. In this type of procedure, the bypass surgery is conducted while the patient&#39;s heart continues to beat. While this type of surgery can be significantly more difficult for the surgeon, the advantages can also be sufficiently great for the patient. As a result, a substantial percentage of bypass procedures are now done off pump. 
   However, for some types of procedures, e.g., aortic valve replacement, it can be effectively impossible to conduct the required surgery off pump using conventional apparatus and methods. 
   However, in pending PCT Patent Application No. PCT/US00/02126, filed Jan. 27, 2000 by Viacor Incorporated for CARDIAC VALVE PROCEDURE METHODS AND DEVICES, which patent application is hereby incorporated herein by reference, there is disclosed a novel apparatus and method for conducting off pump aortic valve replacement. In this patent application there is disclosed, among other things, apparatus comprising a temporary valve and filter which is placed in the aorta downstream from the defective aortic valve and which can effectively replace the functionality of the defective aortic valve while that valve is resected and replaced, and which also prevents debris from the valve resection from passing downstream during the resection procedure. 
   One object of the present invention is to provide a novel apparatus and method for providing improved protection for the coronary arteries during valve resection. 
   Another object of the present invention is to provide a novel apparatus and method for providing improved coronary perfusion during valve resection. 
   Another object of the present invention is to provide, in a single apparatus, used through a single point of entry, (1) a check valve for ensuring unidirectional flow of blood from the heart to the circulatory system, (2) filtration mechanisms for preventing debris from passing down the coronary arteries and/or the aorta, (3) apparatus to augment coronary perfusion, and (4) apparatus for passing instruments from the incision site to the heart. 
   SUMMARY OF THE INVENTION 
   These and other objects are achieved through the provision and use of novel apparatus which, in one preferred form of the invention, comprises a cannula; an aortic filter connected to the cannula; a check valve connected to the cannula distally of the aortic filter; and a coronary artery filter connected to the cannula and extending distally of the check valve. During use, the apparatus is deployed in the aorta so that the coronary artery filter covers the openings (coronary ostia) of the coronary arteries, the check valve is deployed downstream from the coronary artery filter, and the aortic filter is deployed downstream from the check valve. Among other things, in addition to delivering the aortic filter, check valve and coronary artery filter to the surgical site and supporting them there, the cannula also permits the delivery of instruments to the surgical site. 
   In another preferred embodiment, the device further comprises one or more passageways for perfusing the coronary arteries with filtered blood, especially during diastole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like elements and further wherein: 
       FIG. 1  is a schematic drawing showing a first embodiment of the present invention deployed adjacent to the aortic valve of the heart; 
       FIG. 2  is a schematic drawing showing a second embodiment of the present invention deployed adjacent to the aortic valve of the heart; 
       FIG. 2A  is a schematic drawing showing details of the apparatus shown in  FIG. 2 ; 
       FIG. 3  is a schematic drawing showing a third embodiment of the present invention deployed adjacent to the aortic valve of the heart; 
       FIG. 4  is a schematic drawing showing a fourth embodiment of the present invention deployed adjacent to the aortic valve of the heart; and 
       FIG. 5  is a schematic drawing showing a fifth embodiment of the present invention deployed adjacent to the aortic valve of the heart. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   All configurations of the present invention are generally believed to require a seal between the apparatus and the blood flow path to ensure all blood is filtered during systole and the blood flow is blocked during diastole for apparatus configurations that include a temporary check valve to replace the function of the aortic valve. During systole, the seal against the periphery of the aortic valve need not hold back much pressure since the check valve provides very little resistance to blood flow and debris tends to follow laminar flow through the device and valve. During diastole, the check valve closes and the seal between the device and the blood flow path must hold back the diastolic pressure. Blood leaking through the device during diastole is called peri-valvular leakage and blood leaking around the device is called peri-prosthetic leakage. The present invention provides several configurations for sealing during systole and diastole. 
   Looking first at  FIG. 1 , there is shown an apparatus  5  which comprises a first preferred embodiment of the present invention. Apparatus  5  generally comprises a cannula  10 ; an aortic filter  15  connected to cannula  10 ; a check valve  20  connected to cannula  10  distally of aortic filter  15 ; and a coronary artery filter  25  connected to the cannula and extending distally of check valve  20 . Among other things, in addition to delivering the aortic filter, check valve and coronary artery filter to the surgical site and supporting them there, the cannula also permits the delivery of instruments to the surgical site. If desired, coronary artery filter  25  may have a different porosity than aortic filter  15 . By way of example but not limitation, coronary artery filter  25  may have a larger mesh size than aortic filter  15 . Apparatus  5  is configured so that it will make a substantial seal with aorta  30  at  200 . 
   During use, apparatus  5  is deployed in aorta  30  so that coronary artery filter  25  covers the openings of the coronary arteries  35  and seals against the periphery of the aortic valve, check valve  20  is deployed downstream from coronary artery filter  25 , and aortic filter  15  is deployed downstream from check valve  20 . As a result of this construction, during systole, blood can pass into the aorta, past check valve  20  and past aortic filter  15 . Correspondingly, during diastole, blood will be prevented from passing back through check valve  20 . Furthermore, aortic valve  40  may be safely resected with apparatus  5  in place, since (i) during systole, aortic filter  15  will prevent debris from the resection from passing down aorta  30 , and (ii) during systole or diastole, coronary artery filter  25  will prevent debris from passing down coronary arteries  35 . 
   Looking next at  FIGS. 2 and 2A , there is shown an apparatus  5 A which comprises a second preferred embodiment of the invention. Apparatus  5 A generally comprises a cannula  10 ; an aortic filter  15 A connected to cannula  10 ; a check valve  20  connected to cannula  10  distally of aortic filter  15 A; and a coronary artery filter  25 A connected to the cannula and extending distally of check valve  20 . Among other things, in addition to delivering the aortic filter, check valve and coronary artery filter to the surgical site and supporting them there, the cannula also permits the delivery of instruments to the surgical site. If desired, coronary artery filter  25 A may have a different porosity than aortic filter  15 A. By way of example but not limitation, coronary artery filter  25 A may have a larger mesh size than aortic filter  15 A. In addition to the foregoing, coronary artery filter  25 A includes a plurality of impermeable membranes  26 A extending longitudinally along coronary artery filter  25 A. The proximal ends of impermeable membranes  26 A are located adjacent to the upstream side of aortic filter  15 A. Impermeable membranes  26 A serve as liners to channel blood flow to coronary arteries  35  during diastole, as will hereinafter be discussed in further detail. Apparatus  5 A is configured so that it will make a substantial seal with aorta  30  about the perimeter of check valve  20 , except for the portion of the perimeter adjacent to impermeable membranes  26 A. In other words, apparatus  5 A is configured so that it will make a substantial seal with aorta  30  at  200 A in  FIG. 2A , but not at  205 A in FIG.  2 A. 
   During use, apparatus  5 A is deployed in aorta  30  so that the impermeable membranes  26 A of coronary artery filter  25 A are aligned with, and substantially cover, the openings of the coronary arteries  35  and seals against the periphery of the aortic valve, check valve  20  is deployed downstream from coronary artery filter  25 A, and aortic filter  15 A is deployed downstream from check valve  20 . As a result of this construction, during systole, blood can pass into the aorta, past check valve  20  and past aortic filter  15 A. Correspondingly, during diastole, blood will be prevented from passing back through check valve  20 . However, blood will be able to pass around check valve  20  by following the channels or passageways defined by impermeable membranes  26 A, so that the coronary arteries will be perfused during diastole. Furthermore, aortic valve  40  may be safely resected with apparatus  5 A in place, since (i) during systole, aortic filter  15 A will prevent debris from the resection from passing down aorta  30 , and (ii) during diastole, only blood already having passed through aortic filter  15 A will be able to pass down coronary arteries  35 . 
   Looking next at  FIG. 3 , there is shown an apparatus  5 B which comprises a third preferred embodiment of the invention. Apparatus  5 B generally comprises a cannula  10 ; an aortic filter  15 B connected to cannula  10 ; a check valve  20 B connected to cannula  10  distally of aortic filter  15 B; and an impermeable membrane  25 B connected to the cannula and extending distally of check valve  20 B. Among other things, in addition to delivering the aortic filter, check valve and impermeable membrane to the surgical site and supporting them there, the cannula also permits the delivery of instruments to the surgical site. Aortic filter  15 B, check valve  20 B and impermeable membrane  25 B are all adapted to be spaced, along at least some portion of their circumference, from the surrounding wall of aorta  30 , whereby to define one or more passageway(s) alongside the apparatus. In addition, impermeable membrane  25 B is adapted to make a sealing engagement with the periphery of aortic valve  40 , i.e., at  200 B in FIG.  3 . 
   During use, apparatus  5 B is deployed in aorta  30  so that impermeable membrane  25 B engages the periphery of aortic valve  40 , check valve  20 B is deployed downstream from impermeable membrane  25 B, and aortic filter  15 B is deployed downstream from check valve  20 B. As a result of this construction, during systole, blood can pass into the aorta, past check valve  20 B and past aortic filter  15 B. Correspondingly, during diastole, blood will be prevented from passing back through check valve  20 B into the heart, but it will be able to pass back to coronary arteries  35  through the aforementioned peripheral passageway(s) established between apparatus SB and the wall of the aorta. Furthermore, aortic valve  40  may be safely resected with apparatus  5 B in place, since (i) during systole, aortic filter  15 B will prevent debris from the resection from passing down aorta  30 , and (ii) during diastole, only blood having already passed through aortic filter  15 B will be able to pass down coronary arteries  35 . 
   Looking next at  FIG. 4 , there is shown an apparatus  5 C which comprises a fourth preferred embodiment of the invention. Apparatus  5 C generally comprises a cannula  10 ; an aortic filter  15 C connected to cannula  10 ; a check valve  20 C connected to cannula  10  distally of aortic filter  15 C; and a coronary artery filter  25 C connected to the cannula and extending distally of check valve  20 C. Among other things, in addition to delivering the aortic filter, check valve and coronary artery filter to the surgical site and supporting them there, the cannula also permits the delivery of instruments to the surgical site. If desired, coronary artery filter  25 C may have a different porosity than aortic filter  15 C. By way of example but not limitation, coronary artery filter  25 C may have a larger mesh size than aortic filter  15 C. In addition to the foregoing, a plurality of conduits  27 C, formed of impermeable tubular material, are attached downstream of the check valve  20 C and extend, distally, parallel to coronary artery filter  25 C. Apparatus  5 C is configured so that it will make a substantial seal with aorta  30  at 200C. 
   During use, apparatus  5 C is deployed in aorta  30  so that the free ends of conduits  27 C are disposed in the coronary arteries  35 , possibly by a guided catheter, a guidewire or other delivery mechanism, and coronary artery filter  25 C otherwise covers the openings of the coronary arteries  35 , check valve  20 C is deployed downstream from coronary artery filter  25 C, and aortic filter  15 C is deployed downstream from check valve  20 C. As a result of this construction, during systole, blood can pass into the aorta, past check valve  20 C and past aortic filter  15 C. Correspondingly, during diastole, blood will be prevented from passing back through check valve  20 C. However, blood will be able to pass around check valve  20 C by following conduits  27 C so that the coronary arteries will be perfused with blood during diastole. Furthermore, aortic valve  40  may be safely resected with apparatus  5 C in place, since (i) during systole, aortic filter  15 C will prevent debris from the resection from passing down aorta  30 , and (ii) during diastole, only blood already having passed through aortic filter  15 C will be able to pass down coronary arteries  35 . 
   Looking next at  FIG. 5 , there is shown an apparatus  5 D which comprises another preferred embodiment of the present invention. Apparatus  5 D comprises a cannula  10  and a filter  100  connected to the cannula and extending distally of the cannula. Among other things, in addition to delivering filter  100  to the surgical site and supporting it there, the cannula also permits the delivery of instruments to the surgical site. Filter  100  is adapted to make a sealing engagement with the periphery of aertic valve  40 , i.e., at  200 D in FIG.  5 . 
   During use, apparatus  5 D is deployed in aorta  30  so that filter  100  covers the aorta and the openings (coronary ostia) of the coronary arteries  35 . As a result of this construction, during systole, blood will pass through filter  100  before passing down the aorta and/or down the coronary arteries. During diastole, blood will pass through filter  100  before passing down the coronary arteries.