Abstract:
A cannula assembly for applying a flow cannula for the introduction, circulation or diversion of flow media, in particular blood, in the human or animal body. The flow cannula has a main portion and a tip portion. The tip portion is elastic and, in a functional position, is configured to protrude in an arc shape at an angle from the main portion, and in an application position, is held in the direction of the longitudinal extent of the main portion by a guide device. The flow cannula may be fitted for the indication of pulmonary hypertension and pulmonary insufficiency. The one of more flow cannulas so connected to the heart, for example, through an incision of the jugular vein or subclavian vein may be connected, on the outside, to a membrane ventilator, such as a Novalung®, with oxygen supply and/or additional pump support.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority, under 35 U.S.C. §119, of Austrian applications AT 50197/2015, filed Mar. 11, 2015, and AT 50944/2015, filed Nov. 6, 2015; the prior applications are herewith incorporated by reference in their entirety. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The invention relates to a cannula assembly for applying a flow cannula for the introduction, circulation or diversion of flow media, in particular of blood in the human or animal body, wherein the flow cannula has a main portion and a tip portion. The invention further relates to a method for fitting cannulas and for extracorporeal support of patients with pulmonary hypertension. 
         [0003]    Cannula assemblies and catheter systems have long been known in a wide variety of forms. Thus, it is also already known to insert cannulas, from an incision in the inguinal region, through the inferior vena cava into the right atrium of the heart. It is also known, with a catheter assembly of this kind, to use a puncture wire and the front end of the catheter to pierce the septum of the heart and thus fit the cannula in the left atrium of the heart. The trans-septal cannulation of the left atrium proves necessary or advantageous for the temporary treatment of severe pulmonary hypertension and for use in cases of conventional ECMO (extracorporeal membrane oxygenation) with serious saturation problems. 
         [0004]    Severe end-stage pulmonary hypertension can only be treated by lung transplantation. However, in extreme cases, the waiting time for a suitable donor organ can only be bridged by mechanically assisting the pulmonary circulation. The established method for doing this at the present time is peripheral veno-arterial ECMO, but the latter poses a considerable risk to the patient. 
         [0005]    With the present cannula assembly and its application, it is possible, by interventional trans-septal cannulation of the left atrium and additionally of the pulmonary artery, to produce a collateral circulation for the PH (pulmonary hypertension) pathway, as a result of which the patient can be stabilized for a longer period of time. In the aforementioned clinical picture, the procedure can comprise the following steps: 
         [0006]    trans-septal cannulation of the left atrium (arterial return) 
         [0007]    trans-tricuspid cannulation of the pulmonary artery (venous drainage) or normal venous cannulation, 
         [0008]    connection of the cannulas to a conventional Novalung® (in trans-tricuspid cannulation) or to ILA-active (in venous cannulation) or to comparable appliances. 
         [0009]    Whenever cannulas have to penetrate tissue regions, as is necessary when piercing the septum for cannulation of the left atrium for example, the problem is that the cannula is intended to orient the puncture tip of the required puncture wire as far as possible at a 90 degree angle to the tissue region. In the case of the cardiac septum, this is a minor problem if the cannulation is performed by a femoral approach, i.e. via the inferior vena cava, since the cannula guided into the left atrium and the puncture wire guided in the cannula come to lie approximately at a 90 degree angle to the septum. However, in the cannula assemblies known at present, it is not possible to create the preferred approach from the upper half of the body. The approach from above, for example via the superior vena cava, either by a cervical or subclavian route, is much more comfortable for the patient. The approach has greater permanence and is less likely to cause any problems. Moreover, the cannula assembly should be able to be anchored in the septum in order to prevent dislocation. The flow rate that is ultimately obtained must be sufficiently great. It is furthermore desirable to provide the cannula, and also the other parts of the cannula assembly, with antithrombotic properties. Preferably, the assembly should also offer the possibility of closing the defect in the atrial septum if removed. 
         [0010]    Finally, the cannula assembly should also permit connection to the Novalung® system in a way that is permanent and stable, permits simple and rapid exchange of the Novalung® and restricts the physical activities of the patient to the least possible extent. Novalung® is a registered trademark of NovaLung GmbH of Heilbronn, Germany; it represents an interventional lung assist (iLA) device providing for oxygen and carbon dioxide gas exchange. The device is provided for supporting lung function of human beings. The device and related devices that satisfy the same or a similar function will be generically referred to herein as ventilators or membrane ventilators. 
       SUMMARY OF THE INVENTION 
       [0011]    It is accordingly an object of the invention to provide a cannula device and an application method which overcome the above-mentioned and other disadvantages of the heretofore-known devices and methods of this general type and which provide for a cannulation with an approximately 90° puncture of a tissue portion, and in particular the fitting of a cannula through the septum of the heart. 
         [0012]    With the foregoing and other objects in view there is provided, in accordance with the invention, a 
         [0013]    cannula assembly for applying a flow cannula for introducing, circulating or diverting a flow medium in a body, the cannula assembly comprising: 
         [0014]    a flow cannula having a main portion and a tip portion; 
         [0015]    a guide device; 
         [0016]    said tip portion being elastic and being configured to assume a functional position and an application position; and 
         [0017]    said tip portion, in the functional position, projecting from said main portion in an arc shape at an angle relative to said main portion; and 
         [0018]    said tip portion, in the application position, being maintained by said guide device to project from said main portion in a direction of a longitudinal extent of said main portion. 
         [0019]    In other words, the objects of the invention are achieved by the fact that the tip portion is elastic and, in a functional position, is designed to protrude in an arc shape at an angle from the main portion, and that the tip portion, in an application position, is maintained in the direction of the longitudinal extent of the main portion by a guide device. 
         [0020]    Further features of the invention are, among others, the following: 
         [0021]    The guide device preferably has a guide wire, a first dilation cannula, which can be pushed over the guide wire, a second dilation cannula, which can be pushed over the first dilation cannula, and a guide sleeve arranged over the second dilation cannula. 
         [0022]    A further preferred feature is that the first and second dilation cannulas have their tip portions designed, in the same way as the tip portion of the cannula, protruding elastically in an arc shape at an angle from the respective main portions, wherein the first dilation cannula is guided by the guide wire, and the second dilation cannula is guided by the first dilation cannula arranged therein and is guided along the longitudinal extent of the guide wire. 
         [0023]    It is furthermore advantageous if the guide sleeve, during the application, is removable from the tip portion, such that the latter can adopt the arc-shaped curvature, and the guide sleeve is removable in its entirety and replaceable by the cannula, after which the guide wire and the first and second dilation cannulas are removable from the cannula, such that the entire internal cross section of the cannula is freed. 
         [0024]    The invention can further be characterized in that the tip portion of the second dilation cannula has, adjacent to the tip, a dilation balloon whose diameter in the inflated state corresponds to the external diameter of the cannula and whose diameter in the relaxed state is equal to or smaller than the internal diameter of the cannula. 
         [0025]    In the tip portion, the cannula can have a locking device, preferably a balloon, for fixing the cannula. 
         [0026]    The first and second dilation cannulas and the cannula are, in the unsupported state, preferably bent at an angle of 20° to 100°, preferably 60° to 95°, particularly preferably 90°, in the tip portion. 
         [0027]    Preferably, the assembly is designed for trans-septal cannulation of the left atrium of the heart by a cervical approach for the trans-atrial puncture. 
         [0028]    The surfaces of the parts of the assembly are preferably made antithrombotic, in particular heparinized. 
         [0029]    The invention also relates to the use of the assembly for trans-septal cannulation of the left atrium of the human heart by a cervical approach, and furthermore to a method for fitting cannulas and for extracorporeal support of patients with pulmonary hypertension, or also other forms of respiratory insufficiency as defined in the claims. 
         [0030]    With the above and other objects in view there is also provided, in accordance with the invention, a method of fitting a cannula into a body (e.g., a human or other animal body), the method comprising: 
         [0031]    providing a cannula assembly with a flow cannula and inner dilation cannulas, the flow cannula having a main portion and a tip portion, wherein the tip portion is elastic and, in a functional position, projects from the main portion in an arc shape at an angle relative to the main portion, and wherein the tip portion, in an application position, is held by a guide device to project in a direction of a longitudinal extent of the main portion; 
         [0032]    providing a catheter with a guide wire guided inside the catheter; 
         [0033]    inserting a sling through an incision at the jugular vein or subclavian vein and advancing the sling to the femoral vein; 
         [0034]    guiding the catheter with the guide wire from the femoral vein in the inguinal region to the right ventricle, and pushing the guide wire through the septum and anchoring the guide wire there; 
         [0035]    subsequently removing the catheter; 
         [0036]    using the sling to pull the guide wire up to the jugular vein or subclavian vein; 
         [0037]    fitting the cannula assembly over the guide wire from the jugular vein or subclavian vein; and 
         [0038]    after the flow cannula has been fitted, removing the inner dilation cannulas and the guide wire. 
         [0039]    In accordance with an added feature of the invention, there is also provided a method for extracorporeal support of patients with pulmonary hypertension. As described above, a flow cannula is provided as a left atrial cannula for circulation of blood into the left atrium of the heart, and a flow cannula is provided as a pulmonary cannula for diverting blood from the pulmonary artery. Then, a membrane ventilator (e.g., a Novalung® membrane or a similar appliance) with the associated oxygen supply is provided, optionally with pump assistance and the connection cannulas. 
         [0040]    In accordance with an additional feature of the invention, the left atrial cannula is guided out of the body through the incision from the right subclavian vein and the pulmonary cannula is guided out of the body from the left subclavian vein incision and they are connected to the Novalung® membrane via the connection cannulas. 
         [0041]    In accordance with a concomitant feature of the invention, there is provided a method for extracorporeal support of a patient with pulmonary insufficiency. As described above, a flow cannula is fitted as a left atrial cannula for circulation of blood into the left atrium of the heart, and a cannula for venous blood removal is fitted, for example, into the superior vena cava. Then the cannulas are connected to the membrane ventilator and, optionally, to an extracorporeal pump, preferably a centrifugal pump, in order to replace or to support the pulmonary function. 
         [0042]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0043]    Although the invention is illustrated and described herein as embodied in a cannula device and an application method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0044]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0045]      FIG. 1  shows a schematic representation of a cannula assembly according to the prior art; 
           [0046]      FIGS. 2 to 7  show schematic stepwise representations of the structure of the assembly according to the invention and of its use in the human heart for fitting the flow cannula into the left atrium of the heart; 
           [0047]      FIG. 8  shows another schematic representation of the heart in order to explain the route of an additional pulmonary catheter; and 
           [0048]      FIG. 9  shows the assembly of a device for extracorporeal membrane oxidation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a prior art embodiment as disclosed, for example, in U.S. Pat. No. 8,343,029 B2. A catheter  9  is preferably inserted through an incision in the inguinal region and pushed upward through the inferior vena cava  7  into the right atrium  3  of the heart  1  and, with its tip portion, penetrates the septum  28 , such that the catheter ends in the left atrium  2 . However, this position of the catheter, and of the cannula which is inserted with it and passes through the body from the inguinal region to the heart, has the disadvantages described at the outset. 
         [0050]      FIG. 1  also shows, as prior art, an inserted sling  29  which can be guided from the vein in the area of the clavicle down through the superior vena cava  8 , in order that a guide wire provided in the catheter  9  can be pulled upward. However, it is thus not possible to insert a cannula with a suitable volume and a diameter of approximately 5 to 9 mm into the left atrium. 
         [0051]    The procedure according to the invention, using the cannula assembly according to the invention, is explained with reference to  FIGS. 2 to 7 . 
         [0052]    In a first step, as per  FIG. 1 , the guide wire  15  with its puncture tip is pushed through the septum  28 , in a known manner by means of the catheter  9 , into the left atrium  2 . Then, after removal of the catheter  9 , the guide wire is pulled upward with the sling  29  into the jugular vein or the subclavian vein, wherein the end of the guide wire is guided out of the body through an opening of the vein. 
         [0053]      FIG. 2  shows how the guide wire  15  is guided from the superior vena cava  8  to the left atrium  2 . This guide wire (the word “wire” does not imply any limitation in terms of the material) can be very soft and pliable. 
         [0054]    If it is found that the guide wire  15  is too soft in order to properly guide the first dilation cannula  16 , the guide wire can be replaced by a stiffer guide wire, by means of a soft tube, also called sheet, being pushed over the soft wire as far as into the septum, the soft wire being removed, and the stiff wire being pushed in as a new guide wire  24  as far as the left atrium. 
         [0055]    However, a stiff wire can also be pulled in later when the following dilation cannulas are already fitted. 
         [0056]    According to  FIG. 3 , in a next step, the first dilation cannula  16  is pushed in over the guide wire  15  or  24 , and the first dilation cannula  16  has a tip portion  19  which is already bent with sufficient tensioning (but only to such an extent that it can still be straightened by the guide wire), such that the first dilation cannula comes to lie at an angle of about 90° against the septum  28  and can be pushed through the septum  28 . This therefore permits a first and still relatively gentle and narrow approach to the left atrium of the heart from above. 
         [0057]    According to  FIG. 4 , in the next step, a second dilation cannula  17  is pushed over and along the first dilation cannula  16 . In the tip portion  20 , the second dilation cannula  17  is also already bent at about 90° with respect to the main portion  26 , with sufficient pretensioning. However, with the aid of the guide sleeve  18  arranged on the outside, the tip portion  20  of the second dilation cannula is kept straight, in such a way that the cannula can be advanced straight over the entire main portion of the first dilation cannula  16 . The first dilation cannula also contributes to stiffening the second dilation cannula. As soon as the second dilation cannula reaches the position as per  FIG. 4 , the physician prevents the guide sleeve  18  from following the advance movement of the second dilation cannula, such that the tip portion leaves the guide sleeve  18  and, in accordance with the pre-bending, assumes the bent position as shown in  FIG. 5 . The unsupported position of the cannulas as per  FIG. 5  is designated here as the functional position, whereas the supported, straightened position of the respective tip portions is designated as the application position. 
         [0058]    As is likewise shown in  FIG. 5 , the second dilation cannula  17  is also pushed through the septum  28  into the left atrium  2 , wherein a dilation balloon  21  is preferably provided in the tip portion of the second dilation cannula, which dilation balloon  21  can be inflated in a known manner in order to widen the hole in the septum  28  for the cannula that is finally to be inserted. 
         [0059]    In the next step, the guide sleeve  18  is pulled out from the dilation cannulas, and the cannula  10  that is ultimately required is pushed in, which cannula  10  can likewise have an already bent tip portion, and, during the application, when pushing in, the necessary stiffness is provided by the two dilation cannulas that have been introduced beforehand, such that the pre-bending is overcome and the cannula  10  can be pushed inward in a straight shape. As soon as the bending as per  FIG. 6  is reached, the cannula  10  can easily follow the bending and can be pushed through the septum into the left atrium. 
         [0060]    In order to lock the cannula in place, a locking balloon is shown which, as locking device  27 , is balloon-shaped. However, the locking can also be achieved by other means, e.g. by braces. 
         [0061]    As can likewise be seen in  FIG. 6 , the dilation balloon  21  of the second dilation cannula  17  can be relaxed by releasing the air pressure, in such a way that the external diameter in the balloon area corresponds approximately to the internal diameter of the cannula  10 . The path through the septum is thus freed for the cannula  10 . In the inflated state as per  FIG. 5 , the balloon  21  has an external diameter which corresponds to the external diameter of the cannula  10  and thus widens the hole in the septum, in such a way that the cannula  10  can be easily pushed in. 
         [0062]    To end with,  FIG. 7  shows the final position of the cannula  10  from which all the inner parts, namely guide wire  15  or  24  and both dilation cannulas  16 ,  17 , have been pulled out. Thus, the entire cross-sectional volume of the flow cannula  10  is available as a left atrial cannula (LA cannula) in order to produce the desired flow rates and flow conditions. 
         [0063]    The number of the dilation cannulas to be pushed over one another is not limited to two. If the dilation balloon  21  is to be avoided, it is also possible for a third or a fourth cannula with the above-mentioned properties to be pulled over in order to obtain the necessary widening of the opening in the septum and the required cross section of flow in the finally inserted flow cannula  10 . The dilation cannulas preferably have a free inner cross section, which allows the cannula to be pushed over the inner guide wire or over the inner dilation cannula. 
         [0064]      FIG. 8  is a schematic representation of the assembly of a further flow cannula as a pulmonary cannula  35  for cannulation of the pulmonary artery  33 . A conventional pulmonary catheter, which is relatively soft and carries a balloon, is inserted via the superior vena cava  8 . A pulmonary catheter of this kind can be equipped with a guide wire, such that the guide wire, with the catheter, is washed by the natural blood stream through the right atrium  3 , through the tricuspid valve  31  into the right ventricle, and from there through the pulmonary valve  32  into the pulmonary artery  33 . The guide wire should preferably be inserted into the right pulmonary artery  34 . 
         [0065]    As soon as the guide wire has adopted its desired position, it is possible, in the manner described above, for one or more cannulas to be inserted in successive stages, wherein the guide function is taken over by the guide wire, and the cannulas, by being suitably flexible, are also able to bend to the desired shape. 
         [0066]    With the aid of the first flow cannula  10  (LA cannula) inserted into the left atrium as per  FIGS. 2 to 7 , and the pulmonary cannula  35  inserted into the pulmonary artery as per  FIG. 8 , it is possible to divert blood from the pulmonary artery into the left atrium, and, by way of suitable hose connections outside the body, it is possible to attach a portable device in which CO 2  is removed from the blood and O 2  is added. This is shown in  FIG. 9 . 
         [0067]    In  FIG. 8 , the flow cannula  10  (LA cannula) leading to the left atrium is indicated only in the upper portion. The full position can be seen from  FIGS. 2 to 7 . 
         [0068]    Alternatively, instead of removing blood from the pulmonary artery, venous blood can be removed, for example from the superior vena cava. With the aid of a pump (e.g., a centrifugal pump), the venous blood can be returned via the Novalung® or via a comparable device and the LA cannula into the left atrium of the heart. This alternative is preferred for those cases when the pulmonary hypertension is not excessively high and the lung function is intended to be replaced or assisted. 
         [0069]    The procedure and further embodiments are described below: 
         [0070]    End-stage pulmonary hypertension leads to right-ventricular failure. When drug treatment has been exhausted, this failure can be prevented only by mechanical circulatory support. All prior art methods are either performed surgically or are suitable for use only for a short period of time, with no possible mobility of the patient. 
         [0071]    The percutaneous insertion of cannulas by an approach from the upper half of the body, as per the invention, makes it possible to establish a permanent access. In connection with a membrane that removes CO 2  and adds O 2  (e.g., Novalung®, iLA=interventional lung assist), blood can be diverted from the pulmonary artery into the left atrium. This makes it possible to reduce the pressure in the pulmonary artery and at the same time to maintain the oxygen saturation of the arterial blood. The blood flow is purely passive, driven by the high pressure efficiency between pulmonary artery and left atrium, or, if this is not sufficient, by an additional pump drive, for example by means of a centrifugal pump. 
         [0072]    Limited mobility of the patients can be achieved by virtue of the suitable configuration, according to the invention, of the cannulas, in conjunction with a carrier bag structure. 
         [0073]    To realize this concept, the following are needed: 
         [0074]    a suitable cannula for diverting the blood from the pulmonary artery, namely the pulmonary cannula  35 , 
         [0075]    a suitable possibility of connecting this cannula to a connector  30 , as is known, 
         [0076]    a Novalung membrane  36  (with or without pump assistance) or a comparable appliance, 
         [0077]    a suitable possibility of connection  30  of the Novalung to the cannula for returning the blood to the left atrium, namely the LA cannula  10 . 
         [0078]    Furthermore, the carrier bag structure  37  is provided. 
         [0079]    The pulmonary cannula is inserted by percutaneous puncture of the subclavian vein, preferably of the left subclavian vein. To do this, the following steps are necessary: 
         [0080]    puncturing of the vein at the incision  38   
         [0081]    insertion of a first soft guide wire 
         [0082]    inserting over this a catheter with a balloon at the tip. This is similar to a conventional pulmonary catheter but suitable for serving as a guide for a stiffer guide wire to be introduced therein. By inflation of the balloon, this catheter is washed passively by the blood flow through the superior vena cava, the tricuspid valve  31  and the pulmonary valve  32  into the pulmonary artery. Thereafter, a second stiff guide wire inside the balloon catheter is advanced into the pulmonary artery, and the balloon catheter is removed. 
         [0083]    The actual pulmonary cannula is then inserted over the guide wire lying in the pulmonary artery and is positioned there. The guide wire is then removed. If necessary, as an intermediate step, a guide cannula with a wider cross section can also be inserted. 
         [0084]    At its proximal end, the pulmonary cannula  35  has a connection device  30 , which permits quick, simple and stepless connection to the iLA device (e.g., Novalung®). This is achieved using a suitable first connection cannula  39 , such that the necessary configuration is achieved in order to permit direct and unobstructed access to the iLA device. 
         [0085]    The iLA device used corresponds to the conventionally used membrane devices. It can be placed in a suitable carrier device  37  in front of the patient&#39;s chest, such that the patient, although restricted, is still mobile; see  FIG. 9 . The required oxygen supply takes place through an oxygen hose  41  from a non-illustrated, separate oxygen reservoir. If an iLA active with a pump system is used, it is possible for the entire device to be mounted on a support console. Accordingly, the connectors are to be set up in another configuration suitable for this purpose, as is familiar to any medical technician. 
         [0086]    Similarly, a second connection cannula  40  is needed that permits the necessary connection between iLA device (Novalung)  36  and left atrial cannula (LA cannula  10 ). 
         [0087]    The left atrial cannula is inserted as per  FIG. 2  to  FIG. 7  and is then guided from above through the superior vena cava  8  into the heart as far as the left atrium. 
         [0088]    This assembly can be provided for temporary use, for example as a bridging means prior to a transplant, or to improve the overall state of health by general recovery of the patient, possibly also after an operation. However, it can also serve as a permanent support for patients who have no prospect of improvement and are not candidates for a transplant. 
         [0089]    The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
     1  heart     2  left atrium     3  right atrium     4  left ventricle     5  right ventricle     6  cardiac valve     7  inferior vena cava     8  superior vena cava     9  catheter     10  flow cannula (LA cannula)     11  main portion of cannula     12  tip portion of cannula     13  angle     14  guide device     15  soft guide wire     16  first dilation cannula     17  second dilation cannula     18  guide sleeve     19  tip portion of first dilation cannula     20  tip portion of second dilation cannula     21  dilation balloon     22  diameter of dilation balloon when inflated     23  diameter of dilation balloon when relaxed     24  stiff guide wire     25  main portion of first dilation cannula     26  main portion of second dilation cannula     27  locking device     28  septum     29  sling     30  connector     31  tricuspid valve     32  pulmonary valve     33  pulmonary artery     34  right pulmonary artery     35  pulmonary cannula     36  Novalung® iLA ventilator membrane     37  support frame     38  incision     39  connection cannula     40  connection cannula     41  oxygen supply hose