Abstract:
An aortic balloon occlusion cannula for the occlusion of the ascending aorta during cardiac surgery includes a cannula containing several lumina that are separated from one another. The cannula carries two dilatable occlusion balloons positioned at a distance from each other, one of the balloons being neighbored to the proximal end of the cannula which faces the heart and each of the balloons being connected to its own lumen which enables its dilation in independence from the other balloon. The cannula additionally contains at least one further lumen that is connected on the proximal side of the proximal occlusion balloon and on the distal side of the distal occlusion balloon to the lumen of the aorta and is adapted to be connected to an extracorporal blood supply device. A valve is assigned to the part of this additional lumen which ends on the proximal side of the proximal occlusion balloon.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This patent application is a continuation-in-part application of allowed U.S. patent application Ser. No. 10/099,496, filed Mar. 13, 2002, the disclosure of which is incorporated fully herein by reference. 
     
    
     BACKGROUND  
       [0002]     The invention concerns an aortic balloon occlusion cannula for the occlusion of the ascending aorta during cardiac surgery.  
         [0003]     An arteriosclerotically altered ascending aorta represents a problem in the field of cardiac surgery. It occurs in almost all patients who suffer from calcification of the coronary vessels or, to different degrees, in patients with valvular diseases. It is necessary to insert an aortic cannula into the ascending aorta in order to connect for instance a patient, who undergoes a bypass operation, to the extra corporal circulation (heart-lung machine). The blood circulation is separated from the heart by clamping the ascending aorta towards the heart that is proximal, with a metal clamp, which is attached at right angles. There is, however, the danger of a detachment of particles or plaques from the wall of the ascending aorta which are transported by the blood flow especially into the blood vessels of the head and therefore into the brain. This leads to embolies, which appear clinically often in form of neurological failures (cerebral infarction).  
         [0004]     An aortic balloon occlusion cannula is known from the DE 19 15 933 A1. It is used to avoid the risks going along with aortic clamping at right angles during the extracorporeal circulation that is applied during cardiac surgeries. It includes an occlusion cannula that can be inserted into a catheter. Its lumen is connected on both sides to a dilatable balloon, which allows closing the ascending aorta from the inside by means of a balloon occlusion during the ischemic time without an aortic clamping at right angles. A similar aortic occlusion cannula has also been described in U.S. Pat. No. 5,334,142, especially in connection with cardiopulmonary resuscitation. Further embodiments of occlusion cannulae having two dilatable balloons are disclosed in U.S. Pat. No. 5,458,574 and in EP 1 086 717 A1.  
         [0005]     These balloon cannulae, however, do not solve the problems of other dangers, which can also lead to a calcified embolie as a result of an arteriosclerotic ascending aorta.  
         [0006]     In order to be able to suture the vein bypass to the aorta during a bypass surgery, the aorta has to be clamped with a metal clamp over a certain length in the area of the suture. There is a considerable risk of embolie connected with this therapy. In order to provoke a cardiac arrest, it is also necessary to infuse a cardioplegic substance into the ascending aorta. It is also possible that plaques are separated if a cardioplegic conduction is inserted especially for this purpose into the ascending aorta.  
       SUMMARY  
       [0007]     An object of this invention is to offer a solution to the above mentioned problem and to create an aortic balloon occlusion cannula for the occlusion of the ascending aorta during surgeries. This aortic balloon occlusion cannula is adapted to reduce the danger of the separation of calcified plaques from the calcified ascending aorta and to guarantee a careful treatment of the aorta during the surgery.  
         [0008]     The new aortic cannula can be placed into the aorta via the lefthand ventricle. Thus the calcified aorta needs not to be opened and subsequently reclosed. It is just with an arteriosclerotic aorta ascendens that suturing of the aorta can be a problem which occasionally necessitates a partial clamping of this area resulting in an increased risk of embolies caused by calcified particles.  
         [0009]     Furthermore, the new aortic cannula permits the clamping of the ascending aorta from the inside by means of a dilatable occlusion balloon. In addition, the cannula carries a second occlusion balloon that is positioned in a certain distance from the first balloon. It is able to separate an area from the perfusion. This area is determined by the distance between the two balloons. It serves then for the suture of the vein bypasses. With this, the dangerous tangential clamping of an aortic area is avoided. In the meantime, the aortic root perfusion can retrogradely be performed by means of a coronary sinus in order to reduce the ischemic time.  
         [0010]     If the aortic root perfusion is retrogradely applied via the coronary sinus the new cannula can furthermore assume the function of sucking off the aortic root perfusion. It is one of the advantages of the new aortic cannula that, in contrast to the above discussed state of the prior art, the occlusion cannula need not be inserted through the calcified aorta and that, furthermore, the aorta need not be clamped from its outside, neither tangentially nor transversely. In addition, neither the tubing for the aortic root perfusion nor a suction tube need to be additionally inserted into the aorta through a separate further access in the aorta. Finally, the field of the surgical operation remains much clearer as it is the case with the usual technique, for the reason that there are less additional tubings and clamps that tend to encumber the operation field.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The illustration shows an example of the subject of the invention. The following figures show:  
         [0012]      FIG. 1  is a balloon cannula according to the invention in situ in a schematic illustration;  
         [0013]      FIG. 2  is the cannula according  FIG. 1  cut lengthways along the line II-II of  FIG. 1  in a schematic illustration; and  
         [0014]      FIG. 3  is the balloon occlusion cannula according to  FIG. 1  in an axial cut, in a side view and in a very simplified illustration.  
         [0015]      FIG. 4  is a second embodiment of a balloon occlusion cannula according to the invention, illustrated in an axial cut, in a side view and in a very simplified illustration similar to  FIG. 3 .  
         [0016]      FIG. 5  is the cannula according to  FIG. 4  in a cross-sectional view similar to  FIG. 2 .  
         [0017]      FIG. 6  is a further embodiment of a balloon occlusion cannula according to the invention, in a side view and in a very simplified illustration.  
         [0018]      FIG. 7  is a cross-sectional perspective view of the cannula of  FIG. 6  and  
         [0019]      FIG. 8  is an illustration of an application of the cannula of  FIG. 4  to place an endovascular prothesis in an aorta. 
     
    
     DETAILED DESCRIPTION  
       [0020]     The aortic balloon occlusion cannula, which is generally marked by a  1 , is to occlude the ascending aorta indicated at  2 , during cardiac surgeries. It contains a cannula tube  3  that is made out of an elastic material. This material enables the introduction of the cannula tube  3 , while adapting to the required curvatures, into the ascending aorta  2  through a corresponding incision at  4  in the lefthand cardiac ventricle. When inserting the cannula care must be taken to pass the valvola aortae  20  as carefully as possible. Therefore, in the beginning a guide wire is placed into the heart and subsequently the cannula is inserted by means of a guide rod that is located in the cannula tube  3  and provided with a tapered end. This guide rod defines a lumen for said guide wire and is removed from the cannula tube  3  when the cannula is correctly inserted.  
         [0021]     Cannula tube  3  can also be pre-shaped according to the curvature of the ascending aorta. Two dilatable occlusion balloons  5  and  6  that are positioned in a distance from each other, are mounted on the cannula tube  3 . The first balloon  5  is positioned at the proximal end of the cannula tube  3 , facing the heart, while the other balloon  6  ought to be in a distance of approximately 20 to 30 mm from the balloon  5 , closer to the distal end of the cannula tube  3 , facing the body.  
         [0022]     The areas of the outer surface of the cannula tube  3  close to the two occlusion balloons  5 ,  6  are tapered or frustro-conically shaped at  50  and  60 , respectively, or the cannula tube  3  is provided with a frustro-conical headpiece, which means enhance a smooth passage of the valvola aortae  20  when the cannula tube  3  is inserted or removed. For a similar reason the end portions  30  of the cannula tube  3  can be tapered to a point.  
         [0023]     Both occlusion balloons  5 ,  6  consist of an elastic dilatable plastic, e.g. polyethylene which provides sufficient stiffness and consistency of shape in order to guarantee a secure closing of the ascending aorta  2 . The diameter of the two balloons  5 ,  6  is adapted to the inner diameter of the ascending aorta  2  and its size is about 35-45 mm. The axial width of each of the two occlusion balloons is about 1.5 to 2 cm or more. Both occlusion balloons  5 ,  6  can be positioned on the cannula tube  3  either fixed or in such a way that they are movable towards each other in order to enable an adaption to the anatomic situation in each individual case.  
         [0024]     Furthermore the two occlusion balloons can have different axial widthwise dimensions, the occlusion balloon  6  located close to the end being wider than the proximal occlusion balloon  5 .  
         [0025]     The cannula  1  contains several separate lumina. They form independent conduits and can be separated from one another as for instance indicated schematically in  FIG. 2 .  
         [0026]     A first lumen  7 , indicated in  FIG. 3  by a chain dotted line, leads to the first occlusion balloon  5  and permits its dilatation by means of a suitable dilatation liquid (physiologic salt solution). A second lumen  8 , shown in  FIG. 3  by a double chain dotted line, leads to the second occlusion balloon  6  and enables its dilatation by means of the corresponding dilatation liquid.  
         [0027]     Outside of cannula tube  3 , suitable fittings for the supply of dilatation liquid, shut-off valves and controls are assigned to the conduits formed by the lumina  7 ,  8  in order to dilate the occlusion balloons  5 ,  6  during the occlusion of the ascending aorta  2 , and to return them into the non-dilated state. These means and devices are not illustrated in detail. They are well-known.  
         [0028]     A third lumen  9  defines a conduit that opens via openings  140  on the proximal side, facing the heart, of the occlusion balloon  5 . Said conduit is provided with additional openings  14  in the section between the two occlusion balloons  5  and  6 . With the cannula  1  inserted and with an operative valvola aortae  20 , liquid can be sucked-off the portion of the aorta ascendens  2  which is proximal to the occlusion balloon  5  through said openings  14 . Furthermore, said conduit permits to suck liquid off the area between the two occlusion balloons and  6  if the occlusion balloon  5  is not dilated or in case of a potential leakage of the occlusion balloon  5 . The conduit defined by lumen  9  contains a shut-off organ  90  that permits the control of the supply of the heart protecting solution as required. The internal diameter of the lumen  9  is approximately 3 mm (to give an approximate size). The liquid rate for a retrograde myocardial perfusion is in the order of 500 ml per minute, at a maximum. Additional openings may be added to the third lumen which open to the left ventricle for venting. Alternatively, a separate lumen (not shown) may be included in the cannula that opens to the left ventricle for venting, if necessary.  
         [0029]     A wider and larger lumen  11  is enclosed by the cannula tube  3 . It is connected to the lumen of the distal part, i.e. the side facing the body, of the aorta ascendens when the cannula is inserted in the aorta  2  over one or more opening(s)  12  in the wall of the cannula  1 . Lumen  11  forms a blood conduit that is, as indicated schematically in  FIG. 1 , connected to a heart-lung machine  13  which maintains the circulation extracorporally. The diameter of each of the openings  12  is 10 mm or more.  
         [0030]     When the new cannula is used—this cannula can also be named as an aortic endoclamping cannula with double balloon technique and integrated cardioplegic cannula—at first the distal occlusion balloon  6  is dilated after the insertion of the cannula  1  in the aorta ascendens  2  through the incision  4  in the lefthand ventricle.  
         [0031]     With the cannula  1  inserted and with the valvola aortae  20  being in an operative state a cardioplegic solution can be supplied to the heart through a coronary sinus  21  and a conduit  22  that is in the form of a coronary sinus catheter. Said cardioplegic solution is suctioned off through the conduit defining the lumen  9  while the body circulation is supplied with blood from the heart-lung machine  13  over the lumen  11  and the opening(s)  12 . At this time the anastomoses located close to the heart are sutured.  
         [0032]     Subsequently the second occlusion balloon  5  is dilated, so that the aorta ascendens  2  is additionally occluded at this place. The section  17  of the aorta ascendens  2  delimited between the two occlusion balloons  5  and  6  is opened and provided with “punched out” anastomotic holes, where upon the anastomoses are sutured. One of them is shown in  FIG. 3  at  19 . During these proceedings blood is supplied to the heart through the coronary sinus catheter  22 . The blood is sucked-off through the conduit defining the lumen  9 .  
         [0033]     Upon the termination of these measures, the two occlusion balloons  5  and  6  are deflated, and the organism is trained to function without the heart-lung machine. The cannula  1  is taken out of the aorta ascendens  2  through the lefthand ventricle. The cannula tube  3  shows a generally straight or, according to the aorta curved section in the section  17  between the two occlusion balloons  5  and  6 . As shown, the adjacent area  18  can lead approximately at right angles from the area  17 .  
         [0034]     A somewhat simplified embodiment of the aortic balloon occlusion cannula according to the invention is illustrated in FIGS.  4  to  8  of the drawing and marked by a  100 . It comprises a cannula tube  130  that is somewhat similar to the cannula tube  3  of the embodiment shown in  FIGS. 1, 2 . It is also made out of an elastic material and adapted to be introduced into the ascending aorta  2  through a corresponding incision in the lefthand cardiac ventricle. On the cannula tube  130  a dilatable occlusion balloon  61  is positioned close to the open distal end  31  of the cannula tube  130 . The areas of the outer surface of the cannula tube  130  close to the occlusion balloon  61  are tapered or frustro-conically shaped as at  62 , respectively. The cannula tube  130  is provided, at its open end, with a frustro-conical head piece or it is tapered as at  32  to enhance a smooth passage of the valvola aortae  20  when the cannula tube  130  is inserted or removed.  
         [0035]     The cannula  100  comprises several separate lumina. They form independent conduits and are adapted to be connected to different apparatus at their ends remote from the balloon  61 . Of these lumina a first lumen  70  leads to the occlusion balloon  61  and permits its dilatation by means of a suitable dilatation liquid. A second lumen  80  is optionally provided, for example for the supply of a heart protecting solution as required.  
         [0036]     A third lumen  190  defines a conduit that opens via openings  91  on a side of the balloon  61  that is remote from its open end  31 . When inserted into the aorta ascendens this side of the balloon is the proximal side, facing the heart. Finally, there is a wider and larger lumen  110  enclosed by the cannula tube  130 . It corresponds to the wide and large lumen  11  of the  FIGS. 1, 2  embodiment and serves to form a blood conduit when the cannula is inserted into the aorta.  
         [0037]     The cannula illustrated in  FIGS. 4, 5  can be used in a similar way as it is has been described in connection with the  FIGS. 1, 2  embodiment of the cannula  1 . For bypass surgery the cannula tube  130  is inserted through the incision  4  in the lefthand cardiac ventricle and the occlusion balloon is placed at an appropriate location within the aorta ascendens. The vent openings  91  are in such a distance from the balloon  61  that when the balloon  61  is properly located in the aorta ascendens the vent openings  91  are located within the lefthand cardiac ventricle thereby allowing the lefthand ventricle to be relieved.  
         [0038]     Under another aspect the balloon occlusion cannula  100  can be used for occluding the aorta ascendens when an aortic dissection is to be performed. In this case a balloon  61  is used that has preferably an outer diameter in the range of about 50 to 60 mm.  
         [0039]     Under a further aspect the aortic balloon occlusion cannula may be used for combined surgeries, e.g. cardiac surgeries to replace the arcus aortae in combination with placing of an endovascular prothesis in the aorta of a patient. This application is schematically illustrated in  FIG. 8 . A generally tube-shaped endovascular prothesis  65  is placed in the aorta  66 . To do this the prothesis  65  is connected to the cannula tube  130  by inserting the cannula tube  130  into the prothesis  65  and by dilating the balloon  61 , thereby attaching the prothesis to the cannula. By moving the cannula tube  130  the prothesis  65  can be brought to a desired location.  
         [0040]     During all of these procedures the large lumen  110  of the cannula tube  130  allows perfusion of the lower portions of the patient&#39;s body while surgery is performed on the aorta ascendens or on the arcus aortae. For most of these applications the vent conduit  190  should reach close to the balloon  61  with vent openings  91  being located close to the balloon  61 .  
         [0041]     For some applications the vent openings  91  should be located in a greater distance from the balloon  61 . For example, when the vent conduit  190  is used for sucking off a cardioplegic solution, vent openings  91  should be close to the balloon  61  while for other applications the vent openings  91  should be close to the tip of the heart. To avoid the necessity to provide a large number of aortic balloon occlusion cannulae having vent openings  91  that are in different distances from the balloon  61 , the vent conduit can be adjustably supported on the cannula tube  130  as this is schematically illustrated in  FIG. 6 . The vent conduit  190  is in the form of a cylindrical tube made of an elastic material, and on the outer surface of the cannula tube  130  two parallel lips  71  are formed that enclose an inner cylindrical bore  72  in which the vent conduit  190  is received. The two lips  71  are separated from one another by a gap  73  on their radially outer side thereby frictionally clamping the vent conduit  190  between each other. The gap  73  extends over at least a portion of the lengths of the cannula tube  130  and allows the vent conduit  190  to be shifted along the length dimension of the cannula tube  130 . By appropriate adjusting the vent conduit  190  with respect to the annular tube  130 , vent holes  91  can be provided in each desired location along the length dimensions of the cannula tube  130 .  
         [0042]     The vent openings  91  are registered with the gap  73  thereby permitting a free fluid flow into and out of the vent openings  91 .