BACKGROUND OF THE INVENTION In recent years there has been tremendous interest in finding new surgical access approaches for performing cardiac surgery and other cardiovascular interventions. This has been particularly true in the newly emerging area of minimally invasive cardiac surgery. Standard open-chest cardiac surgery typically uses a median sternotomy to gain access into the patient's thoracic cavity. This approach provides excellent exposure of the heart for many surgical interventions. However, the median sternotomy causes a significant amount of trauma, morbidity and pain for the patient and is sometimes the site of complications, such as scarring, tissue adhesions, dehiscence of the sternotomy and infections of the incision. Alternative surgical access approaches have been developed in order to reduce the trauma, morbidity and pain. These alternative approaches have included: thoracoscopic access ports, rib-sparing minithoracotomies, thoracotomy with removal of ribs or costal cartilages, transverse sternotomy, L-shaped, C-shaped and Z-shaped partial sternotomies and subxyphoid ortransdiaphragmatic approaches. In addition, intraluminal approaches from peripheral arterial access sites, such as the femoral, subclavian, axillary and brachial arteries, have been developed for surgical interventions and for interventional cardiology procedures. These various approaches each have their advantages and disadvantages in terms of adequacy and convenience of the surgical exposure of the heart, trauma and morbidity to the patient, and the need for advanced imaging techniques, such as thoracoscopy, videothoracoscopy, ultrasonic imaging and fluoroscopy.

There continues to be a tremendous need for research into improved and alternative approaches for surgical access to the heart and the cardiovascular system.

SUMMARY OF THE INVENTION In answer to this need, the present invention provides a method and apparatus for transsternal access to the ascending aorta and thereby to the heart and the rest of the cardiovascular system. The transsternal access approach allows a variety of diagnostic, interventional and surgical procedures within the aorta, the heart and the cardiovascular system.

The transsternal approach has several advantages. In particular, the sternum is left largely intact, eliminating much of the pain, trauma and morbidity associated with a sternotomy, as well as the problem of dehiscence of the sternotomy. The transsternal approach also spares both internal thoracic or internal mammary arteries (IMA), which is not true of the transverse sternotomy, or the L-shaped, C-shaped and Z-shaped partial sternotomies. This is tremendously important in that the IMA has become the graft conduit of choice for coronary bypass graft surgery (CABG) and transsection of the IMA may ruin the IMA for possible use as a graft vessel in the present or in a future surgery. The transsternal approach also provides a possible path around or through scar tissue formations and adhesions from previous surgeries. The transsternal approach provides an alternative approach into the aorta, the heart and the cardiovascular system when peripheral arterial access is complicated by peripheral vascular disease.

The method of the transstemal surgical access approach begins with a small skin incision inferior to the suprasternal notch and directly over the manubrium or the body of the sternum.

The skin is retracted to expose the sternum. Tissue retraction and exposure of the sternum is relatively simple as there is very little tissue or muscle over the bone at this location. Then a hole is drilled or punched through the sternum, preferably at a level between the first rib and the second intercostal space, which places the hole over the location of the ascending aorta. A roadmap aortogram or a routine angiogram or ventriculogram will provide the surgeon with the necessary landmarks for placement of the transsternal hole. Depending upon patient anatomy, surgical access may also be made through the suprasternal notch or within the parasternal region.

Depending on the procedure to be performed and the instruments to be used, the transsternal hole may be as small as a couple of millimeters or as large as a couple of centimeters in diameter. A non-coring drill may be used to create the transsternal hole or a coring drill may used, particularly if the hole will be large. The core removed by a coring drill may be saved and replaced in the transsternal hole at the end of the procedure.

The anterior mediastinum is crossed and, if necessary, the lungs are retracted aside to extend the transsternal access channel and to expose the ascending aorta. The next step of the transsternal approach depends on the procedure to be performed. In one embodiment of the invention, a transsternal aortic crossclamp is inserted through the transsternal access channel and used to occlude the ascending aorta for performing cardiopulmonary bypass with or without cardioplegic arrest. In another embodiment of the invention, an aortotomy incision is made and a catheter or cannula is inserted into the ascending aorta. In one variation, a transsternal aortic cannula is inserted to deliver oxygenated blood into the aorta, for example for cardiopulmonary bypass. In another variation an intraluminal occlusion catheter is inserted to occlude the lumen of the ascending aorta. The intraluminal occlusion catheter will have an expandable occlusion member that may be an inflatable balloon or an external catheter valve. The intraluminal occlusion catheter may include a cardioplegia lumen having a port upstream of the expandable occlusion member and/or a perfusion lumen having a port downstream of the expandable occlusion member. The intraluminal occlusion catheter may also include additional expandable occlusion members for further segmentation of the aorta and additional perfusion lumens for selective perfusion of the isolated segments of the vasculature. Additionally or alternatively, interventional catheters or other surgical instruments may be inserted through the transsternal access channel for performing surgical repairs on the aorta, the heart valves, the coronary arteries, or other parts of the cardiovascular system.

After completion of the surgical or interventional procedure, the catheters and/or instruments are removed and any aortotomy that has been made is closed. If desired, the core removed by a coring drill may be placed back in the transsternal hole and held in place with a biocompatible surgical adhesive or a surgical closure device. Then, the skin incision is closed using sutures, skin staples, adhesive strips or any other surgical closure device.

Apparatus according to the present invention includes a system of surgical and/or interventional instruments for creating the transsternal access channel and for performing the intended surgical and/or interventional procedures. The instrument system typically will include a sternal drill or punch, which may be coring or non-coring, and at least one additional surgical and/or interventional instrument. The additional instruments may include an aortic crossclamp, a sidebiting clamp, an aortic perfusion cannula, an aortic occlusion catheter, and devices for

performing surgical and/or interventional procedures within the aorta, the heart or the cardiovascular system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is an anterior view of a patient showing the access site for the transsternal access channel. The heart and the ascending aorta are shown in phantom in this view.

FIG 2 is a superior view of a horizontal cross section of the thorax of a patient showing the transsternal access channel through the sternum and into the ascending aorta.

FIG 3 is a left lateral view of a sagital cross section of the thorax of a patient showing the transsternal access channel through the sternum and into the ascending aorta.

FIG 4 is a left lateral view of a sagital cross section of the thorax of a patient showing an aortic crossclamp inserted via the transsternal access channel.

FIG 5 is a left lateral view of a sagital cross section of the thorax of a patient showing an aortic perfusion cannula inserted via the transsternal access into the ascending aorta.

FIG 6 is a left lateral view of a sagital cross section of the thorax of a patient showing an aortic occlusion and perfusion cannula inserted via the transsternal access into the ascending aorta.

FIG 7 is a left lateral view of a sagital cross section of the thorax of a patient showing a selective aortic perfusion catheter inserted via the transsternal access into the aorta.

FIG 8 is a left lateral view of a sagital cross section of the thorax of a patient showing a transsternal introducer sheath inserted via the transsternal access into the ascending aorta.

FIG 9 is a left lateral view of a sagital cross section of the thorax of a patient showing an interventional catheter inserted via the transsternal access into the ascending aorta.

DETAILED DESCRIPTION OF THE INVENTION FIG 1 is an anterior view of a patient showing the access site for the transsternal access channel. The heart and the ascending aorta are shown in phantom in this view. The method of the transsternal surgical access approach begins with a small skin incision 102 inferior to the suprasternal notch and directly over the manubrium or the upper end of the body of the sternum.

The skin around the incision 102 is retracted to expose the sternum. Tissue retraction and exposure of the sternum is relatively simple as there is very little tissue or muscle over the bone at this location. Then a hole 100 is drilled or punched through the sternum. The optimal location of the transsternal hole 100 may vary considerably depending on the patient's anatomy and the procedure to be performed, however, it is generally placed at a level between the first rib and the second intercostal space, preferably directly over the location of the ascending aorta. The transsternal hole 100 may be placed centrally along the median line or it may be placed to the right or the left of the median line depending on the location of the patient's ascending aorta.

Also, the transsternal hole 100 may be drilled perpendicular to the anterior surface of the sternum or it may be angulated in any chosen direction for better alignment with the ascending aorta for the purposes of the intended procedure. A roadmap aortogram or a routine angiogram or ventriculogram will provide the surgeon with the necessary landmarks for placement of the transsternal hole 100.

Variations of the transsternal approach include a suprasternal approach and parasternal approach. In some patients, the position of the ascending aorta within the thorax will favor access via an incision and access hole 100'partially or completely above the sternum in the suprasternal notch. Such a surgical access method may be termed a suprasternal approach. For an access hole 100'partially above the sternum, some portion of the superior part of the sternum may be removed to achieve optimum position and angulation of the access channel to the ascending aorta. In other patients, the thoracic anatomy will favor access via an incision and access hole 100"partially or completely lateral to the sternum in the parasternal region. A parasternal approach such as this may be made through an intercostal space or part of the sternum and/or costal cartilage may be removed to achieve optimum position and angulation of the access channel to the ascending aorta. Other aspects that may affect the choice of using the transsternal, suprasternal and parasternal approaches are the anatomy of other organs within the thorax, the presence of scar tissue from previous surgeries or injuries and emergency conditions warranting rapid aortic access. The following detailed description applies equally to each of these three variations of the surgical approach.

Depending on the procedure to be performed and the instruments to be used, the transsternal hole 100 may be as small as a couple of millimeters or as large as a couple of centimeters in diameter. A non-coring drill may be used to create the transsternal hole or a coring

drill or hole saw may used, particularly if the hole 100 will be large. The core removed by a coring drill may be saved and replaced in the transsternal hole 100 at the end of the procedure.

FIG 2 is a superior view of a horizontal cross section of the thorax of a patient, taken along the line 2-2 in FIG 1, showing the transsternal hole 100 and the transsternal access channel 104 through the sternum and into the ascending aorta. The anterior mediastinum is crossed and, if necessary, the lungs are retracted aside to extend the transsternal access channel 104 and to expose the ascending aorta. The next step of the transsternal approach depends on the procedure to be performed. For procedures that require it, an aortotomy incision 106 may be made through the anterior wall of the ascending aorta to gain access to the aortic lumen. FIG 3 is a left lateral view of a sagital cross section of the thorax of a patient, taken along the line 3-3 in FIG 2, showing the transsternal hole 100 and the transsternal access channel 104 through the sternum and into the ascending aorta.

Apparatus according to the present invention includes a system of surgical and/or interventional instruments for creating the transsternal access channel and for performing the intended surgical and/or interventional procedures. The instrument system typically will include a sternal drill or punch, which may be coring or non-coring, and at least one additional surgical and/or interventional instrument. The additional instruments may include an aortic crossclamp, a sidebiting clamp, an aortic perfusion cannula, an aortic occlusion catheter, and devices for performing surgical and/or interventional procedures within the aorta, the heart or the cardiovascular system.

FIG 4 is a left lateral view of a sagital cross section of the thorax of a patient showing a transsternal aortic crossclamp 108 inserted through the transsternal hole 100 and the transsternal access channel 104 and used to occlude the ascending aorta for performing cardiopulmonary bypass with or without cardioplegic arrest. Alternatively, a sidebiting aortic clamp may be inserted through the transsternal access channel 104 and used to isolate a portion of the aortic wall for performing an aortic anastomosis of a coronary bypass graft or the like. Optionally, the aorta downstream of the transsternal aortic crossclamp 108 may be perfused with oxygenated blood supplied through an aortic perfusion cannula (described in more detail below) placed in the aortic arch via the transsternal access channel 104. Alternatively, an aortic perfusion cannula may be placed by another method or the patient may be perfused through a peripheral perfusion cannula placed in a peripheral artery, such as the femoral, subclavian or axillary artery. In

addition, a cardioplegia cannula (not shown) may be placed in the ascending aorta upstream of the transsternal aortic crossclamp 108 via the transsternal access channel 104 for infusion of a cardioplegic agent to arrest the heart.

FIG 5 is a left lateral view of a sagital cross section of the thorax of a patient showing an aortic perfusion cannula 110 inserted via the transsternal hole 100 and the transsternal access channel 104 and through an aortotomy incision 106 into the ascending aorta. An aortotomy incision 106 is made in the ascending aorta and the aortic perfusion cannula 110 is inserted through the ascending aorta and into the aortic arch. A cardiopulmonary bypass pump, or the like, perfuses oxygenated blood through the aortic perfusion cannula 110 into the aorta. In one particularly preferred embodiment of the aortic perfusion cannula 110, there is a flow diffuser 112 located at the distal end of the aortic perfusion cannula 110 to reduce the jet velocity of blood exiting the aortic perfusion cannula 110.

FIG 6 is a left lateral view of a sagital cross section of the thorax of a patient showing an intraluminal aortic occlusion and perfusion catheter or cannula 120 inserted via the transsternal hole 100 and the transsternal access channel 104 and through an aortotomy incision 106 into the ascending aorta. The intraluminal occlusion catheter 120 will have an expandable occlusion member 122, which may be an inflatable balloon as shown, for occluding the ascending aorta between the coronary arteries and the brachiocephalic artery. Alternatively, the expandable occlusion member 122 may be an external catheter valve. Preferably, the intraluminal occlusion catheter 120 includes a cardioplegia lumen 124 having a cardioplegia port 126 upstream of the expandable occlusion member 122 and a perfusion lumen 128 having a perfusion port 130 downstream of the expandable occlusion member 122. In addition, the intraluminal occlusion catheter 120 includes a balloon inflation or actuation lumen 132 for inflating or otherwise deploying the expandable occlusion member 122 to occlude the ascending aorta. The intraluminal occlusion catheter 120 may also include additional expandable occlusion members for further segmentation of the aorta and additional perfusion lumens for selective perfusion of the isolated segments of the vasculature.

FIG 7 is a left lateral view of a sagital cross section of the thorax of a patient showing a selective aortic perfusion catheter 140 inserted via the transsternal hole 100 and the transsternal access channel 104 and through an aortotomy incision 106 into the ascending aorta. The selective aortic perfusion catheter 140 will have a first expandable occlusion member 144 for occluding

the ascending aorta between the coronary arteries and the brachiocephalic artery and a second expandable occlusion member 142 for occluding the descending aorta downstream of the arch vessels.

The expandable occlusion members 142,144 may be external catheter valves as shown.

Alternatively, the expandable occlusion members 142,144 may be inflatable balloons, as in the previously described embodiment. In one particularly preferred embodiment, the first expandable occlusion member 144 is an antegrade external catheter valve that allows antegrade blood flow past the occlusion member 144, but which hinders retrograde blood flow past the occlusion member 144, and the second expandable occlusion member 142 is a retrograde external catheter valve that allows retrograde blood flow past the occlusion member 142, but which hinders antegrade blood flow past the occlusion member 142.

Preferably, the selective aortic perfusion catheter 140 includes a cardioplegia lumen 146 having a cardioplegia port 148 upstream of the expandable occlusion members 142,144, an arch perfusion lumen 150 having an arch perfusion port 152 between the expandable occlusion members 142,144, and a corporeal perfusion lumen 154 having a corporeal perfusion port 156 downstream of the expandable occlusion members 142,144. In addition, the selective aortic perfusion catheter 140 includes an actuation lumen 158 for deploying the expandable occlusion members 142,144 to segment the aorta. The selective aortic perfusion catheter 140 may also include additional expandable occlusion members for further segmentation of the aorta and additional perfusion lumens for selective perfusion of the isolated segments of the vasculature.

FIG 8 is a left lateral view of a sagital cross section of the thorax of a patient showing a transsternal introducer sheath 160 inserted via the transsternal hole 100 and the transstemal access channel 104 and through an aortotomy incision 106 into the ascending aorta. The transsternal introducer sheath 160 has a tubular body 162 with an internal lumen for inserting interventional catheters or other surgical instruments into the patient's aorta. Optionally, the transsternal introducer sheath 160 may include a trocar (not shown) insertable through the tubular body 162 for making the aortotomy incision 106. Preferably, the transsternal introducer sheath 160 has, at the proximal end of the tubular body 162, a hemostasis valve 164 or the like for sealing around instruments inserted through the transsternal introducer sheath 160 and a side flush port 166 for infusing fluids through the lumen of the tubular body 162.

Optionally, the transsternal introducer sheath 160 may also include, at the distal end of the tubular body 162, an inner expandable sealing member 168 and an outer expandable sealing member 170. The inner and outer expandable sealing members 168,170 are expandable and retractable by means of an actuator 172 on the proximal end of the tubular body 162. In use, the inner and outer expandable sealing members 168,170 are retracted and collapsed against the tubular body 162 for insertion into the transsternal hole 100 and through the transsternal access channel 104. Once the distal end of the tubular body 162 has been inserted through the aortotomy incision 106 into the ascending aorta, the inner and outer expandable sealing members 168,170 are expanded to anchor the transsternal introducer sheath 160 and to seal the aortotomy incision 106. Interventional catheters or other surgical instruments may be inserted through the transsternal introducer sheath 160 for performing surgical repairs on the aorta, the heart valves, the coronary arteries, or other parts of the cardiovascular system.

FIG 9 is a left lateral view of a sagital cross section of the thorax of a patient showing an interventional catheter 180 inserted via the transsternal hole 100 and the transsternal access channel 104 and through an aortotomy incision 106 into the ascending aorta. Optionally, the interventional catheter 180 may be inserted into the ascending aorta using the transsternal introducer sheath 160, described above in connection with FIG 8. Alternatively, some interventional catheters and surgical instruments may be inserted directly through the transsternal hole 100 and the transsternal access channel 104 without an introducer.

In this illustrative example, the interventional catheter 180 is in the form of a coronary stent delivery catheter system. A guiding catheter 182 is inserted into the ascending aorta via the transsternal introducer sheath 160 with the aid of a guidewire (not shown) and maneuvered to engage one of the patient's coronary arteries. Next, a stent delivery catheter 184 is inserted through the guiding catheter 182 and maneuvered across a stenosis or other lesion in the coronary artery with the aid of a steerable guidewire 186. Then, an expandable balloon 188 mounted at the distal end of the stent delivery catheter 184 is inflated to expand the stent 190 in the lesion.

Finally, the balloon 188 is deflated and the stent delivery catheter 184 and the guiding catheter 182 are withdrawn, leaving the expanded stent 190 in place.

Additionally or alternatively, other interventional catheters or surgical instruments may be inserted through the transsternal introducer sheath 160 or directly through the transsternal access channel 104 for performing surgical repairs on the aorta, the heart valves, the coronary

arteries, or other parts of the cardiovascular system. After completion of the surgical or interventional procedure, the catheters and/or instruments are removed and any aortotomy incision 106 that has been made is closed. If desired, the core removed by a coring drill may be placed back in the transsternal hole 100 and held in place with a biocompatible surgical adhesive or a surgical closure device. Then, the skin incision is closed using sutures, skin staples, adhesive strips or any other surgical closure device.

While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that many modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof.