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Description  |
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FIELD OF THE INVENTION
The present invention generally relates to surgery on body tissues and organs. More specifically, the present invention relates to a method and apparatus for temporarily immobilizing a local area of tissue subject to motion, such as the heart
wall, which permits a surgical procedure to be performed on that local area of tissue.
BACKGROUND OF THE INVENTION
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow to
various areas of the heart. This can lead to the discomfort of angina and the risk of ischemia. In severe cases, acute blockage of coronary blood flow can result in irreversible damage to the myocardial tissue including myocardial infarction and the
risk of death.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to merely treat the symptoms, with pharmaceuticals, or treat the underlying causes of the disease, with lifestyle
modification. In more severe cases, the coronary blockage can be treated endovascularly or percutaneously using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, and the like.
In cases where these approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure. This procedure generally consists of the following steps: First, direct access to the heart is
achieved. This is usually done by opening the chest by median sternotomy and spreading the left and right rib cage apart; and opening the pericardial sac to achieve direct access to the heart.
Next, a blood vessel or vessels for use in the graft procedure are mobilized from the patient. This usually entails mobilizing either a mammary artery or a saphenous vein, although other graft vessels may also be used.
Next, a heart-lung or cardiopulmonary bypass is performed. This usually entails arterial and venous cannulation, connecting the bloodstream to a heart-lung machine, cooling the body to about 32 degrees Celsius, cross-clamping of the aorta and
cardioplegic perfusion of the coronary arteries to arrest and cool the heart to about 4 degrees Celsius. The arrest or stoppage of the heart is generally required because the constant pumping motion of the beating heart would make surgery upon the heart
difficult in some locations and extremely difficult if not impossible in other locations
Once cardiac arrest is achieved, then a graft (or grafts) is attached to the relevant portions of a coronary artery (or arteries) followed by weaning from the cardiopulmonary bypass, restarting the heart and decannulation. Finally the chest is
closed.
One area which may create difficulties for the patient and extra expense and time for the procedure involves the cardiopulmonary bypass. In a cardiopulmonary bypass all the patient's blood, which normally returns to the right atrium, is diverted
to a system which supplies oxygen to the blood and removes carbon dioxide and returns the blood, at sufficient pressure, into the patient's aorta for further distribution into the body. Generally such a system requires several separate components,
including an oxygenator, several pumps, a reservoir, a blood temperature control system, filters as well as flow, pressure and temperature sensors.
Problems may develop during cardiopulmonary bypass due to the reaction blood has to non-endothelially lined surfaces, i.e. surfaces unlike those of a blood vessel. In particular, exposure of blood to foreign surfaces results in the activation of
virtually all the humoral and cellular components of the inflammatory response, as well as some of the slower reacting specific immune responses. Other complications from cardiopulmonary bypass include loss of red blood cells and platelets due to shear
stress damage. In addition, cardiopulmonary bypass requires the use of an anticoagulant, such as heparin. This may, in turn, increase the risk of hemorrhage. Finally cardiopulmonary bypass sometimes necessitates giving additional blood to the patient. The additional blood, if from a source other than the patient, may expose the patient to blood born diseases.
Due to the risks incurred during cardiopulmonary bypass, others have attempted to perform a coronary artery bypass graft procedure without cardiac arrest and cardiopulmonary bypass. For example, Trapp and Bisarya in "Placement of Coronary Artery
Bypass Graft Without Pump Oxygenator", Annals Thorac. Surg. Vol. 19,No.1,(January 1975) pgs.1-9, immobilized the area of the bypass graft by encircling sutures deep enough to incorporate enough muscle to suspend an area of the heart and prevent damage
to the coronary artery. More recently Fanning et al. in "Reoperative Coronary Artery Bypass Grafting Without Cardiopulmonary Bypass, "Annals Thorac. Surg. Vol. 55, (Febuary 1993) pgs. 486-489 also reported immobilizing the area of the bypass graft
with stabilization sutures.
While these attempts have achieved some success, they generally require enhanced skill of the surgeon to properly create the anastomsis because, even with sutures, the beating heart continues to move in the relevant area more than desired.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a method and apparatus for temporarily immobilizing a local area of tissue, such as an area of a beating heart, without requiring the use of stabilizing sutures.
It is a further object of the present invention to provide a method and apparatus to facilitate performing coronary artery bypass graft surgery on a beating heart.
It is the further object of the present invention to provide a method and apparatus to perform a coronary artery bypass graft without requiring the heart to be arrested or stopped and the patient coupled to a cardiopulmonary bypass machine.
These and other objectives are met by the present invention which comprises a method and apparatus for temporarily immobilizing a local area of tissue. In particular, the present invention provides a method and apparatus for temporarily
immobilizing a local area of heart tissue to thereby permit surgery on a coronary vessel in that area without significant deterioration of the pumping function of the beating heart. The local area of heart tissue is immobilized to a degree sufficient to
permit minimally invasive or micro-surgery on that area of the heart. The present invention features a suction device to accomplish the immobilization. The suction device is coupled to a source of negative pressure. The suction device has a series of
suction ports on one surface. Suction through the device causes suction to be maintained at the ports. The device further is shaped to conform to the surface of the heart. Thus, when the device is placed on the surface of the heart and suction is
created, the suction through the ports engages the surface of the heart. The suction device is further fixed or immobilized to a stationary object, such as an operating table or a sternal or rib retractor. Thus, the local area of the heart near the
suction device is temporarily fixed or immobilized relative to the stationary object while suction is maintained. In such a fashion, the coronary artery may be immobilized even though the heart itself is still beating so that a bypass graft may be
performed. In addition the suction device may be used in either a conventional, open-chest environment or in a minimally-invasive environment, e.g. endoscopic.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other aspects of the present invention will best be appreciated with reference to the detailed description of the invention in conjunction with the accompanying drawings, wherein:
FIG. 1 is a plan view of the device being used to temporarily immobilize a local area of heart tissue in which access to the heart is achieved through a mini-thoractomy. in FIG. 1.
FIGS. 2a 2b depict a first type of suction device shown in use in FIG. 1.
FIGS. 3a and 3b depict a second type of suction device shown in use in FIG. 1.
FIG. 4 is a longitudinal sectional view of the suction paddle used in the present invention.
FIG. 5 is a cross-sectional view of the suction paddle used in the present invention taken along the line 5--5 of FIG. 4.
FIG. 6 is a longitudinal sectional view of the suction arm used in the present invention.
FIG. 7 is a plan view of the suction arm used in the present invention.
FIG. 8 is a detailed view of a pair of suction devices being positioned on a heart and spread apart.
FIGS. 9 and 10 show the effect of the spread-apart motion depicted in FIG. 8.
FIG. 11 is an example of the motion in the plane parallel to the surface of the heart of a point on heart tissue during one half respiratory cycle when the heart is unrestrained and also depicting the motion of the same point on heart tissue when
the suction devices are used.
FIG. 12 is an enlarged portion of FIG. 11 depicting the motion of the same point on heart tissue when the suction devices are used.
FIG. 13 is an alternate embodiment of the present invention.
FIG. 14 is a plan view of the device being used to temporarily immobilize a local area of heart tissue in which access to the heart is achieved through a median sternotomy.
FIG. 15 is a side view of an alternate embodiment of the present invention, shown placed against the surface of the heart.
FIG. 16 is a bottom view of the alternate embodiment of the present invention device shown in FIG. 15.
FIG. 17 is a side view of a further alternate embodiment of the present invention, shown placed against the surface of the heart.
FIG. 18 is a bottom view of still further alternate embodiment of the present invention.
FIG. 19 is a cross-sectional view of a body showing an alternative method of achieving access to the surface of the heart, and in particular of achieving such access using minimally invasive trocars.
The drawings are not necessarily to scale.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a view of the immobilizing device 11 being used to temporarily immobilize an area of heart tissue. In the preferred embodiment, surgical access to the local area of heart tissue is achieved through a mini-thoracotomy, preferably
performed within either the fourth or fifth intercostal space. An incision 10 of approximately 10 centimeters is made into chest cavity between the ribs (seen here in phantom.) The rib cartilage may be temporarily removed and the ribs surrounding the
incision slightly spread apart using a retractor (not shown) to provide adequate surgical access to the mammary artery and the heart. As seen, a pair of suction devices 12, 13 are introduced. The first suction device 12 is introduced through a small
stab wound 8 in between the ribs approximately 10 cm. below incision 10. This stab wound is made in any acceptable manner. Incidentally, once the surgery has been completed, the stab wound may be used for the thorax drain after the closure of the
chest. As discussed below with reference to FIG. 19, the suction device has a covering 180, made from latex rubber, over the distal end when it penetrates the chest wall in order to avoid blood and tissue from entering the suction ports and block
suction apertures. Once suction device is introduced, covering 180 is removed and the distal end is positioned onto heart. The second suction device 13 is introduced through incision 10 onto the surface of the heart. As seen, the distal end of each
suction device is ultimately positioned in the local area of heart tissue to be immobilized, i.e. on either side of a coronary artery upon which a graft is to be made.
As seen, suction devices 12, 13 are secured using securing devices 14, 15 respectively to a stationary object, such as surgical table 16. Of course other objects besides the surgical table may be used as a stationary object, including the floor,
ceiling or even the patient, such as a portion of the skeletal system of the patient, e.g. the sternum. In the preferred embodiment, each securing device 14, 15 is a variable friction arm, model no. 244 available from Manfrotto Nord, Inc. of Zona
Industriale di Villapaiera, I-32032 Feltre BL, Italy. Each securing device 14, 15 has a series of elbow joints 17 which may be locked in position. Thus the securing device permits the suction device to be locked into any position desired within
three-dimensional space. Although not show, each securing device (or each suction device or both) may also be interconnected such that a truss type structure is created and the entire stiffness or rigidity of the immobilizing device 11 is improved.
Suction devices 12, 13 are coupled to a suction source 114 through lines 20, 21. Suction source 114 is preferably the standard suction available in the operating room and coupled to the devices with a two liter buffer flask (not shown) for each
device. Suction is provided at a negative pressure of between 200-600 mm Hg with 400 mm Hg preferred. As seen, each suction device has essentially two portions, a paddle 22 and an arm 23. FIGS. 2 and 3 detail suction devices 12 and 13 respectively.
Turning now to FIGS. 2a and 2b,FIG. 2a is a side view of a suction device 12 showing its placement against the outline of a heart. As seen, the distal end of suction device comprises a paddle 22 and arm 23 coupled together by a continuous hinge
or neck 71. Paddle 22 has a generally planar surface which conforms generally to the curvature of a heart 1, shown here in outline. In the preferred embodiment, suction arm 23 is coupled to suction paddle 22 such that suction paddle 22 may be rotated
or bent to achieve the desired orientation relative to arm 23. This is accomplished by neck 71. Neck 71 is fashioned to be relatively bendable, that is to be bent by hand into the desired orientation, as opposed to paddle 22 and arm 23, which are
rigid. In the preferred embodiment suction paddle 22 and suction arm 23 are constructed of stainless steel 316, while neck 71 is constructed of stainless steel 321. Of course other means may be provided to permit paddle 22 to move or rotate relative to
arm 23 other than making neck 71 to be malleable by hand, such as a locking hinge as well as a remotely actuable joint, as is well known in the art. See for example, U.S. Pat. No. 5,374,277 of Hassler, incorporated herein by reference. A remotely
actuable hinge is believed particularly advantageous for a suction device used endoscopically. In an alternate embodiment paddle may be fixed in a rigid orientation relative to arm. As seen, arm 23 has a suction lumen 30 therethrough which communicates
with a suction conduit 31 in paddle 22 through neck lumen 72. Suction conduit 31 in paddle 22 further communicates through suction hole 32 (best seen in FIG. 2b) to suction port 33.
FIG. 2b is a view of the bottom of suction device 12. As seen, in the preferred embodiment four suction ports 33 in a row are featured, although the specific or exact number and position used may vary. Each suction port 33 has a suction
aperture 32, each of which are preferably located at a position off center from suction port 33. Suction apertures 32 are positioned off center from suction ports 33 so that if a large upwelling of tissue is caused by the suction (which may occur as a
blister or bell-shaped curve) the tissue will not immediately close off the suction by obstructing suction aperture 32, as it would if the aperture were in the center of suction port 33. In addition, each suction aperture 32 has a much smaller diameter
as compared to the diameter of suction port 33. This creates a high resistance pathway between suction port 33 and suction conduit 31 which permits the loss of a tissue-to-port seal in one suction port (and thus loss of fixation of the suction port to
the tissue) to not also cause a precipitous pressure drop in the remainder of the suction ports. In the preferred embodiment suction aperture 32 has a diameter of 2 mm and suction port 33 has a diameter of 6 mm.
Turning now to FIGS. 3a and 3b,FIG. 3a is a side view of a suction device 13 shown in FIG. 1. As seen, the distal end of suction device 13 comprises paddle 22 and arm 23 coupled together by a continuous hinge or neck 71. Paddle 22 has a
generally planar surface which conforms generally to the curvature of a heart 1. In the preferred embodiment, suction arm 23 is coupled to suction paddle 22 such that suction paddle 22 may be rotated or bent along any of the three axes to achieve the
desired orientation relative to arm 23. This is accomplished by neck 71. Neck 71 is substantially similar to that discussed in FIG. 2a but for the fact that suction device 13 has suction paddle 22 at an angled orientation to suction arm 23. In the
preferred embodiment suction paddle 22 of suction device 13 is perpendicular to suction arm 23, although other angular orientations may be used.
FIG. 3b is a view of the bottom of suction device 13. As seen, in the preferred embodiment suction paddle 22 of suction device 13 is substantially similar to that described in FIG. 2b.In the preferred embodiment suction aperture 32 has a
diameter of 2 mm and suction port 33 has a diameter of 6 mm.
FIG. 4 is a longitudinal cross-sectional view of suction paddle 22 used in immobilizing device 11. As seen, paddle 22 has a series of suction ports 33 each of which is connected to suction conduit 31 through a suction aperture 32. Each suction
port 33 has generally straight, cylindrical sides. Of course other configurations may be used, such as cone-shaped suction ports, dome-shaped suction ports, etc.
FIG. 5 is a cross-sectional view of the suction paddle 22 taken along the line 5--5 of FIG. 4. As seen, suction port 33 is connected to suction conduit 31 through suction aperture 32. Suction paddle 22 has a canted or slanted surface 36 at the
top. Through this type of surface, area 37 may be better accessed for performing surgical procedures.
FIG. 6 is a longitudinal cross-sectional view of suction arm 23. Distal end 71 of suction arm 23 has neck 71 (not shown in this FIG.) fixed thereto. As seen, arm 23 has a suction lumen 30 therethrough which communicates with suction conduit 31
in paddle 22 through neck lumen 72 of neck 71 (shown in phantom in this FIG.). As seen in FIG. 7, which is a plan view of suction arm 23, proximal end 75 has a series of knurled ridges 76 to facilitate coupling a suction line coming from suction source
(not shown in this FIG) to suction arm 23.
FIG. 8 is a detailed view of a pair of suction devices 12, 13 being positioned on a heart and spread apart. As seen, paddles 22, 27 of each device generally are placed in the area 34 in which temporary immobilization of the heart tissue is
desired. When used for a coronary bypass graft, area 34 typically will have a coronary artery 35 running therethrough. Area 34 is between paddles 22, 27. Once placed about area 34, suction is then created in the suction ports (not shown in this view.)
Through the suction, the device then is fixed to or grabs hold of the heart tissue.
Once the suction is created and the paddles are secured to the heart tissue, each of the suction devices are then spread slightly apart as shown by the arrows 40, 41 to the positions shown as 42, 43. The effect of this spreading apart is to
cause a tension to be created in the area 34 of the heart tissue between the paddles. The tension causes the area 34 to be further immobilized, and in particular in the Z-direction, i.e. in the direction normal to the plane defined by the surface of the
heart. This is represented in FIGS. 9 and 10.
As seen in FIG. 9, the area of heart tissue between the paddles, even with the placement of the paddles, still has some vertical motion, shown here as arrow 50. When paddles 22, 27 are slightly spread apart to cause a tension in that area 34 of
tissue between the paddles, as depicted in FIG. 10, then the amount of movement in the area 34 between the paddles 22, 27 due to the tension is further decreased, especially in the Z-direction, i.e. the direction perpendicular to the surface of the heart
1. Once the paddles 22, 27 are thus positioned and secured and the area of the tissue is temporarily immobilized, the coronary artery in that area may be operated upon.
In the preferred embodiment, the anastomosis of the coronary artery may be accomplished through any acceptable end-to-side or side-to-side technique. Of course, other methods of performing the anastomosis may be used, such as those methods which
may be performed endoscopically.
FIG. 11 is an example of the motion in the plane parallel to the surface of the heart of a point on heart tissue during one half respiratory cycle when the heart is unrestrained and also depicting the motion of the same point on heart tissue when
the suction devices are used. Line 60 is a tracing of the motion of a point of tissue on the cardiac surface. As seen by line 60, a point on the cardiac surface moves approximately 15 mm in each direction. Generally, each loop of movement depicts the
motion of the beating heart within one cardiac cycle. Thus, loop 61 occurs due to one cardiac cycle. Loop 62 occurs due to the next cardiac cycle, but the entire heart has shifted in location somewhat due to the inflation or deflation of the lungs
associated with respiration. Line 63 shows the motion of the same point of heart tissue when the suction device is | | |
