Abstract:
A surgical procedure for revascularization the myocardium, comprising the steps of: directing a generally cylindrically shaped first nozzle into a heart wall being treated; forming a first or main channel in the heart wall from the ventricle into the myocardium of the heart by the nozzle; removing a generally cylindrically shaped tissue core through the nozzle, from the heart wall during formation of the first or main channel. A set of tributary channels may be made in the heart wall from and in communication with the main channel by an arrangement of radially directed fluid jets subsequent to the creation of that main channel.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to arrangements for bringing blood flow into the myocardium through channels that are connected directly to the ventricle.  
         [0003]     2. Prior Art  
         [0004]     Coronary bypass surgery consists of bringing blood from a source of pressure through grafts that are attached to the coronary arteries where they have been surgically opened beyond the obstructed area. If the coronary arteries were too small or too severely diseased for such surgery, they were also too small for balloon dilation and stent insertion. Therefore, these patients were left with incomplete revascularizations. This could lead to subsequent need for re-operation for angina, heart attacks, rhythm disturbances or death.  
         [0005]     Coronary arteriograms show only the larger arteries, and can not show the small arteries. Therefore, incomplete revascularization may not be recognized when it is due to branch occlusions, such as in diabetics, old people, and patients after a heart attack.  
         [0006]     In areas of inadequate perfusion as above, mechanical methods were attempted to make ventriculo-myocardial channels using primarily cannulas or trocars. They failed apparently because they produced slits instead of holes.  
         [0007]     A system using lasers to create ventriculo-myocardial channels was used more successfully and became the recognized alternative surgical approach when coronary bypass grafting and angioplasty was not feasible. Unfortunately the laser channels often closed as well. The closure of these channels is postulated to be due to the high temperature generated by the laser which causes scar formation around the channels that in turn close them.  
         [0008]     It is the object of this invention to revascularize hearts that are not amenable to coronary bypass graft surgery or angioplasty, thereby increasing the life expectancy and quality of life of these patients. This is accomplished by the formation of ventriculo-myocardial channels that remain open, by creating tributary channels that increase the distribution of blood through the myocardium, and by creating a system that can be readily accepted, both in ease of use and in cost.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     In a preferred embodiment of the invention, a series of main channels are formed by a nozzle that emits jets of high pressure fluid from an annular orifice placed on the heart&#39;s surface. The nozzle and high pressure fluid are advanced through the myocardium. This proces is called TMFR or Trans Myocardial Fluid-Jet Revascularization.  
         [0010]     Tributary channels may also be formed from each main channel by high pressure jets emitted from radial orifices in the surface of a sealed chamber surrounding the nozzle.  
         [0011]     The fluid-Jets may create debris during formation of these main channels and tributaries in the heart&#39;s wall. This debris must be kept out of the bloodstream, to prevent embolization. In the formation of the main channels, except at the instant of penetration, the spent cutting fluid and any cutting debris it contains is kept isolated from the bloodstream by the uncut section of the myocardium. Debris formed at the moment of penetration is suctioned away through a tube at the center of the nozzle and is disposed of. Similarly, fluid used to form the tributary channels is kept isolated from the blood stream.  
         [0012]     The system for supplying the fluid-Jet with fluid includes a reservoir containing fluid, a pressure pump, and a control system including solenoid valves for starting and stopping the fluid flows. Typically, a gear pump is used to generate the pressure in the fluid supplied to the nozzle arrangement. The fluid-Jet fluid is a physiologic solution such a Lactated Ringer&#39;s Solution. A signal from an electrocardiogram may be connected to a control unit computer and is used to synchronize the start of flow of each pressurized stream with the pause between heartbeats.  
         [0013]     The thickness of the heart wall as measured by ultrasound is used to controllably adjust a mechanical stop in a collector ring adjacent the distal end of the nozzle to correctly limit the nozzle&#39;s depth of penetration through the myocardium. This permits the nozzle to penetrate far enough to form the channel, but not so far that the seal at the distal end of the nozzle loses contact with the newly-formed channel. Cuts created by Fluid-Jets extend beyond their orifices, so the adjustment of the stop on the nozzle is an approximation only.  
         [0014]     Procedurally, the system&#39;s control system is then turned on, including the pressure and suction pumps. At the start of the revascularization, the annular opening of the collector ring disposed circumferentially on the nozzle is centered over the locus of the new main channel. The probe is inserted through the opening, and the fluid-Jet fluid flow is started. As the main channel is formed, the probe is pushed into the wall of the heart until is restrained by the stop on the collector ring touching the heart wall. The fluid is immediately turned off to minimize the cutting debris from mixing with the blood stream and also to minimize damage to the formed elements for blood flow.  
         [0015]     Penetration of the heart wall causes a sudden loss of vacuum in the nozzle&#39;s inner suction tube, and its measurement (loss of vacuum), may be used to automatically shut off the tissue-penetrating fluid-Jet flow. The drop in pressure also confirms that the penetration is complete. Alternatively, the probe&#39;s contact of a switch in the collector ring&#39;s mechanical stop with the heart&#39;s surface may be used to shut off the fluid-Jet fluid flow.  
         [0016]     A further step in the procedure occurs when the pressurized fluid to the tributary nozzle orifices is turned on for a predetermined period. The fluid pressure is then reduced below that required for cutting for an additional period, to permit the flushing away of any remaining debris. The fluid-Jet flow is then turned off, and the probe and collector ring are removed. The entrance to the main channel on the heart surface is sutured if required.  
         [0017]     The procedure is then repeated as needed. Typically, five to eight channels are required per square inch to treat poorly perfused myocardium, less then the number needed with TMLR. Ideally, channels are created on alternate sides of diseased arteries at a spacing of about 1-1½ inches.  
         [0018]     The fluid pressure at the orifice must be at least 1000 to 2000 psi to cut the tissue. Higher pressures reduce the cutting time, but the system&#39;s maximum pressure is limited by the strength of the nozzle tube and the stiffness of the hoses. The nozzle&#39;s outer diameter is determined by the space requirements of its tubing and flow passages. The diameter of the main channel generated in a heart wall is determined by the diameter of the annular orifice, which is smaller than the nozzle&#39;s outer diameter. A typical main channel diameter is expected to average about 0.04″, while a typical nozzle&#39;s outer diameter may be about 0.07″ if there are tributary fluid-jets, and a diameter of about 0.05″ in the single probe nozzle embodiment (without the tributary forming side nozzles). The stretchiness of the myocardium is expected to allow the heart&#39;s wall to accommodate the diametrical interference without difficulty.  
         [0019]     The tributary channels generated by the side nozzles in the nozzle probe apparatus are expected to range from about ⅜ to ¾″ in length and about 0.02 to 0.04″ in diameter. Typically, there are preferably about six tributary side orifices per probe, positioned 180 degrees apart around the circumference of the nozzle and fairly evenly distributed through the thickness of the myocardium. When used near the inter-ventricular septum, no tributary channels may extend toward the septum, to avoid injury to the conducting bundles. Generally, the direction of the tributaries is roughly perpendicular to the main channel and parallel to the surface of the heart.  
         [0020]     Tributary channels may be created with heating the fluid-jet fluid to attempt to cause angioneogenesis, but not heated so hot so as to cause denaturing of protein and scarring of the heart wall.  
         [0021]     An alternative embodiment of the present invention is to form the main channels in the heart wall by the utilization of a manually pressed sharpened cannula instead against the wall of the heart instead of a pressurized fluid-Jet to cut the core. The cannula would have distal end with a sharpened edge oriented externally, and removal of debris would be accomplished by suction through a central lumen of the cannula. Residual core material is removed after each penetration and subsequent withdrawal, preferably by a pulse of high pressure fluid introduced at the cannula&#39;s proximal end. The cannula may be in yet a further embodiment, be fitted with an outer fluid-jet jacket with appropriate radially directed nozzles therein, to create tributary channels and to provide angioneogenesis in a manner similar to the aforementioned fluid-jet nozzle embodiments.  
         [0022]     The invention thus comprises a surgical procedure for revascularization the myocardium, comprising one or more of the following steps: directing a generally cylindrically shaped first nozzle into a heart wall being treated; forming a first or main channel in the heart wall from the ventricle into the myocardium of the heart by the nozzle; removing a generally cylindrically shaped tissue core through the nozzle, from the heart wall during formation of the first or main channel; placing a heart wall tissue cutting arrangement on a distal end of the nozzle; and placing a heart wall tissue withdrawing arrangement on a proximal end of the nozzle. The surgical procedure may include: supporting a first conduit co-axially around the first nozzle so as to form a longitudinally directed first annular passageway between the nozzle and the first conduit; providing a pressurized cutting fluid into the first passageway from a controllable pressurized fluid source to direct pressurized fluid from a distal end of the nozzle, for cutting the heart wall. The surgical procedure may include one or more of the following: a sharpened annular edge on the distal end of the nozzle. The surgical procedure may comprise a vacuum conduit in communication with the first nozzle to facilitate removal of the tissue core from the heart wall and through the first nozzle; forming a chamfered distal end on the nozzle and the first conduit so as to direct the cutting fluid in an inward conically shaped direction to reduce the diameter of a tissue core removed from the wall; arranging a plurality of sideway directed orifices through the first conduit adjacent the distal end thereof, and jetting a pressurized fluid through the sideway directed orifices to generate a plurality of tributary channels in the main channel in said wall of the heart being treated; inserting a second conduit between the nozzle and the first conduit to define a further annular passageway; introducing a pressurized fluid into both the first annular passageway and the second passageway from a pressurized fluid source, to provide tissue cutting of the heart wall and to provide tissue debris removal means therewith; arranging a tissue engaging nose piece arrangement on the distal end of the second conduit so as to provide a tissue sealing arrangement adjacent an annular pressurized fluid-emitting orifice thereat; moving the nozzle longitudinally so as to dimensionally alter the annular pressurized fluid emitting orifice; placing a longitudinally adjustable heart wall engaging plenum adjacent the distal end of the nozzle; attaching the plenum into communication with a vacuum source to remove debris from the heart wall during a channel generating revascularization procedure; forming a main channel into a heart wall; forming a plurality of tributaries generally perpendicular with respect to the main channel and into the wall of the heart; and evacuating debris from the tributaries through an outer annular channel while evacuating core tissue from the main channel through the nozzle.  
         [0023]     The invention may also comprise an apparatus for performing a revascularization procedure on a myocardium, comprising: an elongated hollow nozzle having a proximal end and a tissue piercing distal end; and a first conduit arranged co-axial with the nozzle to define an annular fluid directing passageway therebetween, and a controllable pressure source in communication with the passageway.  
         [0024]     The apparatus may include a vacuum arranged in communication with the proximal end of the nozzle to withdraw a core plug of tissue from the nozzle; an annular plenum for sealing the nozzle during a procedure and for withdrawing debris generated therewith. The plenum may have an adjustment means thereon to limit the depth of a nozzle may travel into a heart wall.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which:  
         [0026]      FIG. 1  is a side elevational view of a fluid-emitting tissue-piercing probe assembly constructed according to the principles of the present invention;  
         [0027]      FIG. 2   a  is a side elevational view, in longitudinal section, of a nozzle for forming a main channel in a heart wall;  
         [0028]      FIG. 2   b  is a view similar to  FIG. 2   a  showing a nozzle forming a main channel in a heart wall, removing a longitudinal segment thereof;  
         [0029]      FIG. 3  is a side elevational view, in longitudinal section, of a nozzle arrangement, including an outer conduit arranged for forming tributaries in a heart wall;  
         [0030]      FIG. 4  is a side elevational view of the nozzle arrangement shown in  FIG. 3 , with a collector ring arranged thereon for removal of debris from the channel formation procedure;  
         [0031]      FIG. 5  is a schematic representation of a pressurized fluid source which is arranged to provide pressurized fluid to the nozzle assembly of the present invention;  
         [0032]      FIG. 6  is a side elevational view in longitudinal section of a cannula for forming a main channel in a heart wall; and  
         [0033]      FIG. 7  is a further embodiment of the nozzle shown in  FIG. 6  using a cannula and an outer conduit for forming a main channel and tributary channels in a heart wall.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]     Referring now to the drawings in detail, and particularly to  FIG. 1 , there is shown the present invention which includes a nozzle assembly or probe  2  for performing trans-myocardial fluid-jet revascularization. The probe  2  comprises an elongated, heart wall tissue withdrawing nozzle  4  which is attached to and in fluid communication with an expander  6 , an elbow  8 , and a securement conduit  9 . The diameter of nozzle  4  is small because the main channels to be formed in a heart wall are small. The diameter of conduit  9  is larger than the nozzle  4 , for greater strength and also to reduce drops of fluid flow pressure therethrough. The expander  6  is arranged to connect the nozzle  4  to the elbow  8 .  
         [0035]     An elongated hollow, fluid conduit enclosing handle  10  is communicatively attached to the securement conduit  9 . The securement conduit  9  and internal conduits from the nozzle, if any, are attached in a leak-proof manner to a proximal connector  12 . Openings in the proximal connector  12  are connected in a leak-proof manner to one or more pressure or tissue carrying hoses  16  contained in an enclosure cable  14 . The enclosure cable  14  is also attached to the proximal end of the proximal connector  12 . One embodiment of the invention includes the enclosure cable  14  carrying an internal hose or cable for transmitting a pressure signal to a control system  11 , disclosed in  FIG. 5 .  
         [0036]     The probe or nozzle assembly in one preferred embodiment includes a nozzle  20  as shown in  FIG. 2   a  which nozzle  20  is used for forming a main channel arrangement  27  in a heart wall  30 . The  FIG. 2   a  shows the nozzle  20  as it appears before the completion of the main channel  27  through the heart wall  30 . The nozzle assembly comprises an outer conduit  22  that forms the outer boundary of an annular passage  24  for conveying pressurized fluid  18  from a source  130 , as shown in  FIG. 5 , to an annular orifice  34  in the distalmost end of the nozzle  20 . As with all of the nozzles of the present invention, the proximal end of the tubular conduit that penetrates the heart&#39;s wall  30  is preferably tapered outwardly, so as to be attached to the conically shaped expander  6 , which is shown in  FIG. 1 .  
         [0037]     The inner boundary of channel  24  is defined by an inner conduit  26 . The distalmost ends  32  of both conduits  22  and  26  are chambered radially inwardly to deflect the annular fluid-jet flow inwardly. This causes the outer diameter of a heart wall core  38  being removed to be smaller than the inside diameter of the inner conduit  26 , preventing the heart wall core  38  from becoming stuck during removal attempts by suction, through the inner conduit  26 .  
         [0038]     The fluid-jet forms the main channel by removing heart tissue and creating an annular space  36 . The spent fluid is emitted through an innermost channel  40  within inner conduit  26 , and out through the vacuum system at a distal outlet  42  in the conduit  26 .  
         [0039]     The same nozzle  20  is shown in  FIG. 2   b , as it appears just after the main channel  27  has been extended so as to penetrate the heart wall  30 , forming an inner opening  44 . The penetration of the nozzle  20  has caused the wall core material  46  to become detached from the heart wall  30 , allowing it to be suctioned away through inner conduit  26 .  
         [0040]     An embodiment of a combination nozzle  48  is shown in  FIG. 3 , which nozzle  48  may be utilized to form both the main channel  27  and a plurality of tributary channels  72 . The nozzle  48  provides an outer passage  52  for fluid-jet fluid  60  to produce the tributary channels  72  from radially directed orifices  80  in an outer conduit  50 . The outer passage  52  is bounded by the outer conduit  50  and a middle conduit  54 . The nozzle  48  also includes an inner passage  56  for conveying main channel fluid-jet fluid  62  from its pressure source shown in  FIG. 5 , to an annular orifice  76  defined by the annular gap at the distalmost ends of the middle and innermost conduits  54  and  58  and the interior of an annularly disposed, tissue-spreading nose piece  76 , which is attached to the distal exterior of the middle conduit  54 .  
         [0041]     The internal slope of the annular orifice  76  makes the removed wall core  46  smaller than the inside of inner conduit  58  to keep it from getting plugged. Dimples  78  on the distal inner side of the middle conduit  54  keep the inner conduit  58  centered in the nose piece, thereby keeping the annular orifice  76  annularly uniform. The area of the orifice  76  is adjustably controlled by adjusting the longitudinal location of the longitudinally displaceable inner conduit  58  and then fixing it in place. An annular protuberance  79  of the nose piece  74 , as shown in  FIG. 3 , forms a seal with the main channel  27  in the heart wall  30 , to prevent the leakage of spent tributary fluid from entering the bloodstream in the ventricle of the heart. It uses the flexibility of the heart, rather than an elastomer, to form the seal. It is made large enough to form a seal but not so large as to create trauma.  
         [0042]     A collector ring  81 , as shown in  FIG. 4 , comprises an elastomer seal  84  attached to a metal threaded ring  82 . The elastomer seal  84  comprises an annular elastomer sleeve  85  attached to an annular elastomer washer  87 . The washer  87  is flexible enough to allow the nose piece protrusion  79  to pass through its central opening during the introduction and removal of the nozzle  48  therethrough. A microswitch  86  is arranged in communication with the computer control  204  through a proper circuit  89 , to control advance and pressure of the nozzle arrangement  48  during a treatment procedure. A vacuum source  99  is shown in fluid communication with the connector  94  and is also in controlled communication with the controller unit  204  for vacuum/pressure conformance.  
         [0043]     At the start of revascularization procedure, the annular distal edge of the collector ring  81  is pressed against the outer surface of the wall  30  of the heart being treated. The pressure of the ring  81  causes the lower edge of sleeve  85  to seal against the surface of the heart, while the inner annular opening of washer  87  seals against the nozzle assembly  48 . This enables a suction to be maintained in the plenum defined by he ring  81  and the surface of the heart, for removal of cellular debris and water-jet flow  96  out a side channel fitting  94  to a suction hose, not shown for clarity.  
         [0044]     The conical hole  200  of the longitudinally adjustable, threaded disk  88  mates with the distalmost end of the conical surface of the expander  6  shown in  FIG. 1 , to control and limit the heartward advancing motion of the nozzle  48  therein. Without this depth penetration control, the nose piece protrusion  79  might extend beyond the end of the main channel  27 , eliminating its sealing during formation of the tributary channels  72 . The position of disk  88  is adjusted with the use of threads  92  by rotating the disk  88  in the ring  81 .  
         [0045]     Pressurized fluid-jet fluid is supplied by a controlled pressure supply system  202  represented in  FIG. 5 . It includes a reservoir  130  for containing fluid-jet fluid  132 . The fluid may be heated by a heater  134  to a temperature controlled by a thermometer  136 . The lid  138  of the reservoir includes a vent  140  and a fluid intake port  142 . The fluid-jet fluid  144  is controllably withdrawn through conduit  146  by the suction of pump  148  and compressed, leaving through conduit  154 .  
         [0046]     When a main channel is being formed, solenoid valve  156  is opened, allowing fluid-jet fluid to flow through conduit  158  to nozzle  2 . At least a portion of conduit  158  is a hose in communication with the nozzle assembly  48 .  
         [0047]     The controlled flow from the pump is determined by the controlled opening of for example, a pair of solenoid valves # 1  and # 2 , both of which are normally closed. In order to avoid having to cycle the motor for pump  148  and prevent over-pressuring the system  202  when both solenoid valves are closed, the fluid-jet fluid  150  is recycled to the reservoir  130  through a return conduit  172 , a back pressure regulator  174 , and a conduit  152 . The regulator  176  is adjusted to a sufficiently high pressure to remain shut when either of the solenoid valves is open. The system  202  is controlled and timed through a computer controller  204  in proper communication with the system  202  and sensors, arranged within the handle  10  and nozzle arrangements  20  and  48 , for control of vacuum removal of debris, and for timing and force/pressure sensing of the pressurized fluid in the nozzle assemblies  20  and  48 , the control system not being fully shown for clarity of the drawings.