System for introducing a pump

Abstract

The invention resides in the field of introducing fluid pumps into a lumen and relates to a system for introducing a pump into a lumen which comprises a first sheath and a pump to be introduced into the first sheath, or a system which has a pump with a distal pump unit and a shaft catheter which emerges proximally to the pump unit. According to the invention one or two sheaths are used, the distal pump unit being pulled firstly into the distal end of one sheath, in order to avoid damage to a shaft catheter. Subsequently, the sheath receiving the pump unit is transferred into a further sheath or a receiving lumen.

Claims

1. An intracardiac blood pump system comprising: a sheath for delivering an intracardiac blood pump assembly percutaneously, the sheath having a flared distal end with a continuous surface, the distal end formed of a fixed-shape material; and the blood pump assembly coupled to the flared distal end of the sheath, the blood pump assembly comprising: a proximal section with an outer diameter that is smaller than an inner diameter of the sheath, a radial shoulder adjacent to and distal from the proximal section, wherein the radial shoulder has a constant outer diameter that is larger than an outer diameter of the flared distal end of the sheath, and a distal portion with an outer diameter that is smaller than the outer diameter of the shoulder.

2. The system of claim 1, wherein the proximal section is positioned inside the flared distal end of the sheath such that the radial shoulder abuts the flared distal end of the sheath.

3. The system of claim 2, wherein movement of the blood pump assembly in a proximal direction relative to the sheath is limited by the radial shoulder abutting the flared distal end of the sheath.

4. The system of claim 3, wherein the flared distal end of the sheath is a trumpet-like widening which facilitates movement of the blood pump assembly into the sheath.

5. The system of claim 1, wherein the sheath is a tear-off sheath which can be torn off.

6. The system of claim 1, wherein the sheath is formed at least in part of plastic.

7. The system of claim 1, further comprising a drive shaft coupled to the blood pump assembly, and a rotatable impeller disposed on the drive shaft.

8. The system of claim 7, wherein the rotatable impeller in a compressed state can be introduced into a blood vessel within the sheath.

9. The system of claim 8, wherein the rotatable impeller can operate in an expanded state when the sheath is removed.

10. The system of claim 7, wherein the rotatable impeller can be compressed into the sheath for withdrawal from a blood vessel.

11. The system of claim 1, wherein the fixed-shape material is not flexible.

12. The system of claim 1, wherein the fixed-shape material is metal.

13. An intracardiac blood pump system comprising: a sheath for delivering an intracardiac blood pump assembly percutaneously, the sheath having a flared distal end with a continuous surface; and the blood pump assembly configured to slide in proximal and distal directions relative to the flared distal end of the sheath, the blood pump assembly comprising: a proximal section with an outer diameter that is smaller than an inner diameter of the sheath, and a radial shoulder adjacent to and distal from the proximal section, wherein the radial shoulder has a constant outer diameter that is larger than an outer diameter of the flared distal end of the sheath, wherein the flared distal end of the sheath has a fixed shape.

14. The system of claim 13, wherein the proximal section is configured to be positioned inside the flared distal end of the sheath such that the radial shoulder abuts the flared distal end of the sheath.

15. The system of claim 14, wherein movement of the blood pump assembly in the proximal direction relative to the sheath is limited by the radial shoulder abutting the flared distal end of the sheath.

16. The system of claim 15, wherein the flared distal end of the sheath is a conical widening which facilitates movement of the blood pump assembly in the proximal direction into the sheath.

17. The system of claim 13, wherein the sheath is a tear-off sheath which can be torn off.

18. The system of claim 13, further comprising a drive shaft coupled to the blood pump assembly, and a rotatable impeller disposed on the drive shaft.

19. The system of claim 18, wherein the rotatable impeller in a compressed state can be introduced into a blood vessel within the sheath.

20. The system of claim 19, wherein the rotatable impeller can operate in an expanded state when the sheath is removed.

21. The system of claim 18, wherein the rotatable impeller can be compressed into the sheath for withdrawal from a blood vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is intended to be explained subsequently in more detail with reference to a few embodiments. There are shown:

(2) FIG. 1 a schematic overview of a vascular system with an introduced first sheath;

(3) FIG. 2 a detailed view of a cut-out of FIG. 1;

(4) FIG. 3 an embodiment of a system according to the first aspect of the invention;

(5) FIG. 4 an embodiment of a pump;

(6) FIG. 5 an embodiment of a system according to the second aspect of the invention;

(7) FIGS. 6, 7 pulling a pump into a second sheath;

(8) FIG. 8, 9 transfer of a pump from a second into a first sheath;

(9) FIG. 10 an embodiment of the system according to the second aspect with a device according to the third aspect of the invention;

(10) FIG. 11 a cross-section of the representation of FIG. 10;

(11) FIG. 12 an embodiment according to the first and third aspect of the invention;

(12) FIGS. 13a and 13b an embodiment of a distal end of a sheath according to the second aspect of the invention;

(13) FIG. 14 an embodiment of a long sheath and the arrangement thereof during the operating state of the pump unit;

(14) FIGS. 15a and 15b sketches for clarification of curves.

DETAILED DESCRIPTION OF THE INVENTION

(15) As already mentioned initially, FIG. 1 shows a schematic representation of a human vascular system in which a first sheath 10 configured as an introducer sheath has been introduced into the femoral artery with application of the Seldinger technique.

(16) In FIG. 1, a guide wire 12 which extends into to the left ventricle is shown furthermore. The tubular portion 11 of the first sheath 10 is introduced into the artery such that the proximal end of the first sheath 10 is situated outside the femoral artery and hence can be used to introduce for example a pump. On the one hand, it is possible to thread the pump onto the guide wire 12 in order to guide the pump into the left heart ventricle by means of the guide wire.

(17) It is a method according to the invention to guide the tubular portion 11 of the first sheath 10, guided by the guide wire, into the left ventricle and subsequently to remove the guide wire 12 from the first sheath. A possible pump unit is subsequently guided through the first sheath lumen into the vicinity of or into the left ventricle 4.

(18) The invention is presently represented merely with reference to introduction of a pump into the left ventricle for assisting a heart function. However, it can be detected easily toy the person skilled in the art that the pump can be disposed also at other positions in the natural body vascular system. Furthermore, it is evident to the person skilled in the art that the invention is not restricted exclusively to the natural body vascular system but is suitable for introduction of a pump into any lumina. This includes for example lumina which are defined by tubes, into which a pump unit is intended to be introduced for conveying a flow.

(19) In FIG. 2, the region of FIG. 1 in which the first sheath 10 is guided through the natural body tissue from outside into the lumen L.sub.G of the femoral artery 2 is represented. The first sheath thereby comprises a tubular portion 11 which is connected proximally to a valve 13. The tubular portion 11 defines a lumen L.sub.1 which has an inner diameter d.sub.11. The latter widens in the manner of a trumpet towards the proximal end of the tubular portion 11. The trumpet-like widening 14 leads to the diameter of the valve 13 being greater than the inner diameter d.sub.11.

(20) The valve 13 concerns a haemostatic valve which is known in prior art and comprises a housing 15 and a gasket 16. The haemostatic valve prevents fluid situated in the lumen L.sub.G from emerging outwards through the lumen L.sub.1.

(21) In the illustration of FIG. 3, the first sheath 10 of FIG. 2 is coupled to a second sheath 20. Merely a tubular portion 21 of the second sheath 20 which defines a lumen L.sub.2 with an inner diameter d.sub.21 is shown. The distal end of the second sheath 20 which is coupled to the valve 13 thereby has such an outer diameter that it can be introduced into the valve 13. The inner diameter d.sub.21 is however greater than the inner diameter d.sub.11.

(22) At this point, reference may be made to the fact that the position of the valve is not restricted to the proximal end of the first sheath but can also be disposed at other positions inside the first sheath, such as for example the distal end of the first sheath or in the centre. It is sufficient for introducing the distal end of the second sheath into the proximal end of the first sheath if the proximal end of the first sheath has an inner diameter which is greater than the outer diameter of the distal end of the second sheath. The diameter of the lumen of the first and second sheath (apart from the proximal end of the first sheath and the distal end of the second sheath) can be uniform or different or the lumen of the respective sheath can be tapered.

(23) The first and second sheath and also the distal pump unit are configured such that the distal pump unit can come to be situated in the first and second sheath, whilst the proximal end of the second sheath is situated in the distal end of the first sheath or is coupled thereto.

(24) A pump situated in the lumen L.sub.2, not illustrated, tan now be transferred from the second sheath lumen L.sub.2 into the first sheath lumen L.sub.1 by pressing. Subsequently, the pump is transported through the first sheath lumen L.sub.1 to the position in the vascular system at which the pump is intended to develop its action. The pump can either be guided on a guide wire or be introduced without a guide wire through the first sheath lumen.

(25) A possible embodiment of a pump 30 is explained in more detail with reference to FIG. 4. The pump 30 comprises a distal pump unit 31 and a shaft catheter 32 which abuts against the proximal end of the distal pump unit 31. At its proximal end, not illustrated, the shaft catheter 32 has a coupling for coupling the shaft catheter 32 to a drive device. The drive device sets a flexible shaft which extends in the shaft catheter 32 in rotation, which shaft in turn actuates the distal pump unit 31.

(26) The distal pump unit comprises a pump housing 33 which is produced from intersecting nitinol struts. The nitinol housing is provided in parts with a coating 34 which extends distally and proximally to a rotor 35 disposed in the housing 33. The rotor is connected to the shaft 36 which extends through the shaft catheter 32 and is thus set in rotation. The housing and the rotor are compressible, i.e. the pump is s self-compressible pump. The unfolding of the pump is performed after the distal pump unit is pushed out of the distal end of one sheath. For compression of the pump, the distal pump unit is pulled into the distal end of a sheath lumen. The sheath lumen thereby has an inner diameter which is at least greater than the outer diameter of the shaft catheter.

(27) The distal pump unit is constructed such that the housing surrounding the pump is essentially fixed in the axial direction relative to the rotor, i.e. the rotor is not removed from the housing during the implantation but remains in the same.

(28) Optionally, the pump has a discharge hose 37 which defines a flow channel for the pumped fluid, situated proximally to the rotor 35. At the proximal end of the discharge hose 37, outlet openings which are not illustrated in more detail are situated.

(29) Of course, the pump can also be switched from a pumping operation to a suction operation so that the pump no longer conducts fluid from the distal end to the proximal end, but vice versa.

(30) A detailed description of a further suitable pump can be deduced for example from the publication EP 2 047 872 A1.

(31) The function of the system according to the second aspect is now intended to be explained with reference to FIGS. 5 to 9.

(32) In FIG. 5, a pump 30 which corresponds essentially to the pump 30 according to FIG. 4 is represented. For simplification, details of the pump are not shown. Merely the bulbous housing and also the pigtail situated distally to the bulbous housing are represented, which housing prevents suction of the heart pump against the heart wall. The shaft catheter 32 extends proximally to the distal pump unit 31. Surrounding a region 38 of the shaft catheter 32, a second sheath 20 is disposed, which comprises a lumen L.sub.2, the inner diameter d.sub.21 of which is less than the diameter of the distal pump unit 31 in the decompressed or unfolded state.

(33) The pump 30 illustrated in FIG. 5 is a compressible pump, i.e. the distal pump unit 31 which comprises infer alia the pump housing and the rotor situated therein is configured such that it can be compressed, i.e. reduced in its diameter. After a quality tester or for example a doctor has been able to convince himself of the correct function of the pump 30, e.g. by observing the rotational movement of the rotor unit situated in the distal pump unit 31 during a test run, the distal pump unit 31 is pulled into the lumen L.sub.2 of the second sheath 20 by pulling the shaft catheter 32 in the proximal direction. By pulling the pump into the second sheath 20, bending or damage to the shaft catheter or the shaft extending therein is avoided. The pump 30 illustrated in FIG. 5 and the second sheath 20 surrounding the region 38 of the shaft catheter 32 form a system 200 which makes it possible to test the function of the pump 30 well before an operation and subsequently to compress the pump by pulling the distal pump unit 31 into the distal end of the second sheath 20 and thereby to avoid damage to the shaft.

(34) Although the system according to the first and second aspect can be produced both with actively decompressible pumps and with self-decompressible pumps, it is suitable in particular for self-decompressible pumps, i.e. pumps, the distal pump unit of which outside the sheath automatically assumes the original size again.

(35) In FIG. 6, an intermediate step when pulling the distal pump unit 31 into the lumen L.sub.2 of the second sheath 20 is represented. It is detectable that the distal pump 31 is compressible and can be brought to a smaller diameter, so that the distal pump unit 31 can be received in the lumen L.sub.2 of the second sheath 20.

(36) Furthermore, a coupling 39 which abuts against the shaft catheter 32 is represented in FIG. 6, which coupling enables coupling of the shaft extending in the shaft catheter to a drive unit. Since the coupling 39 has an often larger outer diameter than the inner diameter of the lumen L.sub.2, the second sheath 20 is generally put on in the distal direction before assembly of the coupling 39 from the proximal end of the shaft catheter 32 so that the pump in system 200, i.e. the pump with the second sheath 20 situated proximally to the distal pump unit 31 and the premounted coupling 39, is delivered. In FIG. 6, a slight trumpet-like widening of the distal end of the second sheath 20 is represented. The trumpet-like widening 24 facilitates pulling the distal pump unit 31 into the lumen L.sub.2 of the second sheath 20.

(37) In FIG. 7, the distal pump unit 31 is finally situated completely in the lumen L.sub.2 of the second sheath 20. The second sheath 20 differs from the sheath 20 merely by two premounted gripping units 22 which enable better holding or removal of the second sheath 20 when pulling the distal pump unit 31 into the lumen L.sub.2 or subsequent tearing off. Advantageously, in the case of a pigtail being present, this is likewise pulled into the lumen L.sub.2 so that the distal pump unit 31 together with components of the pump situated distally to the distal pump unit 31is situated in the lumen L.sub.2.

(38) In FIG. 8, it can be detected how the system 200 comprising pump 30 and second sheath 20 is combined in operating connection with the first sheath 10 to form a system 100 according to the first aspect of the invention. Firstly, the second sheath 20 is introduced by its distal end into the valve of the first sheath 10. As soon as the distal tip of the second sheath 20 abuts against the trumpet-like widening 14 of the first sheath 10, by pushing the pump in the distal direction, the pushing being effected by means of pushing the shaft catheter 32, the pump is transferred, from the second sheath 20 into the first sheath 10. The diameter of the distal pump unit 31 is hereby reduced further to the inner diameter d.sub.11 of the lumen L.sub.1.

(39) In FIG. 9, the subsequent step in which the distal pump unit 31 is situated completely in the lumen L.sub.1 of the first sheath 10 is represented. The fact that the distal pump unit 31 is situated completely in the lumen L.sub.1 of the first sheath 10, can be identified for example with reference to a colour marking 50 which is applied on the outside of the shaft catheter 32.

(40) Subsequently, the second sheath 20, which is configured as a peel-away sheath, is removed from the shaft catheter 32 by tearing off the peel-away sheath from the proximal towards the distal end and pulling it off the shaft catheter 32. The directed tearing off from the proximal to the distal end can be assisted by notches A but is based predominantly on the orientation of the molecular chains of the plastic material which is used from the proximal to the distal direction.

(41) After the peel-away sheath has been removed, the pump 30 is guided again inside the lumen L.sub.1 of the first sheath 10 up to the desired position.

(42) Reinforcement of the second sheath 20 is unnecessary, in particular when pulling the distal pump unit 31 into the distal end of the second sheath lumen L.sub.2 since the danger of bending of the shaft during a pulling movement is greatly reduced.

(43) During transfer of the pump from the second sheath into the first sheath, as illustrated with reference to FIGS. 7 to 9, the second sheath can include a structure which reinforces it in the form of an introduced wire, or the tubular portion 21 of the sheath 20 is not produced from a flexible plastic material but from a fixed-shape plastic material or metal.

(44) A further possibility for pulling the pump into the second sheath, when moving forwards in the pump 30 in the distal direction, i.e. in particular when transferring the pump 30 from the second sheath into the first sheath, resides in retaining the second sheath 20 by means of a device 40 for retaining the second sheath.

(45) The device for retaining a portion of the second sheath 20 is represented in cross-section in FIG. 11. The device 40 has an upper and a lower half 41 or 42 which are connected to each other via a hinge 43. In the first or second half 41 or 42 there is situated respectively a recess, the recesses in the illustrated, closed state of the device 40 defining a cavity 44. The cavity 44 configured as a lumen is configured furthermore such that a second sheath 20 can be retained frictionally in the cavity. This can be achieved either via correspondingly chosen inner diameters of the cavity 44 or outer diameters of the second sheath 20 or rough surfaces in the region of the cavity 44. Also knobs in the region of the cavity 44 can produce a frictional fit.

(46) As can be detected with reference to FIG. 10, the cavity 44 extends without, curvature and hence does not allow any bending of the shaft which extends in the shaft catheter 32 if the latter is pushed forwards in the distal direction by means of a transverse force. In addition, the device 40 makes an improved grip possible for an operator of the system 200 for introducing the pump.

(47) In FIG. 12, the device 40 with the cavity 44 in which a second sheath 20 is retained is represented. The distal end of the device 40 thereby lies on the proximal end of the valve 13 of the first sheath 10. In the case of such a coupling between the first sheath 10 and the second sheath 20, simplified introduction of a pump from the second into the first sheath can be achieved.

(48) In FIG. 13a, a distal end 22 of an embodiment of the sheath 20, according to the second aspect of the invention is represented. The distal end 22 has an internal and external tapering of the edge 23 surrounding the lumen L, as a result of which an improved introduction of the sheath into the natural body lumen or a first sheath according to the first aspect of the invention is possible. Likewise, the distal end 22 can be the end of second sheath according to the first aspect of the invention. A possible proximal end can have the same shape of configuration.

(49) FIG. 13b shows a further variant; an additional feature hereby is that the distal end has such a flexible or elastic configuration that it widens slightly when pulling in the pump head and consequently facilitates insertion. After complete insertion of the pump head, the distal end again adopts extensively the original shape. During introduction of the distal end of the second sheath into the first sheath, the distal end of the second sheath can also be fitted by the elastic/flexible tapering to the proximal end of the first sheath and consequently can facilitate coupling.

(50) The systems, represented in the present documents, according to the first, second and third aspect hence enable simplified handling and improved introduction of pumps into a lumen.

(51) Subsequently, another possible variant of a method for introducing a pump into a left ventricle is intended to be portrayed. As a preparatory measure, the pump is firstly filled with sterile physiological common salt solution and hence completely deaired. Subsequently, the peel-away sheath placed proximally to the distal pump unit is pushed forwards up to a possibly present discharge hose. The peel-away sheath has a diameter of approx. 10 Fr. After the peel-way sheath has been pushed forwards up to the discharge hose, the peel-away sheath is surrounded by the device for retaining the second sheath. Subsequently, the distal pump unit, possibly with a slight rotational movement is pulled into the peel-away sheath by exerting a pulling movement on the shaft catheter in the proximal direction. The pump is displaced into the second sheath until a possibly present pigtail is likewise hidden in the peel-away sheath. By means of these steps, it is possible to test the functional capability of the pump even before an operational procedure and to introduce the pump only subsequently into a sheath without requiring to act under pressure of time. For example, the puncturing of the vascular system for introducing the first sheath is only implemented subsequently. In order to save time, it is however also possible in this way that an assistant prepares the pump whilst the user already implements the puncturing in parallel.

(52) After for example a 9 Fr introducer sheath has been introduced into the left ventricle, a possibly present dilator is pulled out of the introducer sheath and removed therefrom.

(53) Subsequently, the pump retained in the peel-away sheath, which is surrounded for example by the device for retaining the second sheath, for example a 2 cm long portion of the distal end of the peel-away sheath protruding at the distal end of the device, is coupled to the haemostatic valve of the introducer sheath until the tip of the peel-away sheath abuts inside the introducer sheath. Subsequently, the pump is transferred from the peel-away sheath into the introducer sheath by pushing the shaft catheter.

(54) As soon as the distal pump unit has been transferred completely into the introducer sheath, as can be checked for example with reference to an optical marking on the shaft catheter shaft, the device for retaining the second sheath can be removed from the second sheath and the peel-away sheath can be torn off and withdrawn from the shaft catheter. Subsequently, the pump is pushed forwards inside the introducer sheath up to the left ventricle. The introducer sheath is subsequently pulled back from the left ventricle tip to the beginning of the descending aorta.

(55) The positioning of the distal pump unit in the left ventricle can be Checked for example by radioscopy. For this purpose, an X-ray-visible marking is situated on the pump housing or the pump housing itself is X-ray-visible. Likewise, the outlet region, i.e. the outflow openings of a discharge hose, should be situated in the region of the ascending aorta. This can also be checked with an X-ray-visible marking. A possibly present pigtail catheter tip should abut against the tip of the left ventricle.

(56) In order to remove the pump from the ventricle, this is pulled back into the introducer sheath by means of a tensile force applied on the shaft catheter and is removed, in a compressed state, from the arterial vascular system. Subsequently, the introducer sheath and further remaining components are removed from the vascular system.

(57) A further aspect of the invention is the use of a long sheath during implantation and explantation of the pump. The long sheath serves not only, as is common in prior art, for introducing the pump into a natural body lumen but for guiding the pump through the sheath lumen to the vicinity of the operating location. It is hereby advantageous if, in the medical field, the sheath has a length between 40 and 120 cm. The length is generally determined by the subsequent operating location of the pump and the physical constitution of the patient. The long sheath can be provided, on the one hand, by the first sheath of the system according to the first aspect of the invention and, on the other hand, by the sheath of a system according to the second aspect of the invention. A schematic representation of a long sheath and of the distal pump unit in the operating state cars be deduced from FIG. 14.

(58) The long sheath 60, which is formed by a first or second sheath of the system according to the first aspect of the invention or a sheath of the system according to the second aspect of the invention, ends at the aortic arch 3, the shaft catheter 32 of the pump 30 extending through the lumen of the long sheath and emerging at the distal end of the sheath lumen. The distal pump unit 31 is located in the ventricle 4 in the operating state.

(59) Alternatively, the length of the long sheath can be chosen such that this ends in the ventricle before decompression of the pump so that the distal pump unit is unfolded only in the ventricle.

(60) At the proximal end of the long sheath, the coupling 39 is situated, which serves for coupling the shaft which extends in the shaft catheter to a drive unit.

(61) The long sheath has such a length that it is possible to place the distal pump unit in the vicinity of the operating location.

(62) Essentially two functions are attributed to the long sheath. One the one hand, the long sheath enables guidance of the pump to the operating location. Since the pump is compressed in the sheath lumen of the long sheath, conveyance of the pump to the place of use, relative to sole guidance by a guide wire, is simplified. In addition, this serves for avoiding complications or injury to the inner vascular walls. In particular in the case self-unfolding pumps, i.e. pumps which have no active actuatable components for unfolding the distal pump unit, this is a significant simplification relative to guidance of the pump unit by means of a guide wire. On the other hand, the long sheath enables simplified explantation of the pump. The pump unit, after completion of the conveying performance, is pulled into the distal end of the long sheath by a pulling movement of the shaft catheter, consequently compressed and subsequently withdrawn either through the sheath, lumen of the long sheath or pulled, together with the long sheath, out of the natural body lumen.

(63) If the pump is withdrawn together with long sheath, out of the natural body lumen, bleeding of the femoral artery is stopped with a pressure bandage. Alternatively, the pump can be withdrawn from the sheath lumen of the long sheath. Then a further guide wire can be placed through the lumen of the sheath, via which then, after removal of the sheath, a device for closing the puncture can be guided. As a result, improved stoppage of the bleeding can be achieved.

(64) If the first sheath of the system according to the first aspect of the invention is configured as a long sheath, a system according to the second aspect can be introduced into the proximal end of the long sheath. Subsequently, the second sheath is possibly withdrawn from the shaft catheter and the pump is guided through the sheath lumen of the long sheath to the operating location of the pump.

(65) As an alternative hereto, the long sheath can also be formed by a sheath in the sense of the system of the second aspect of the invention. A first sheath, in the sense of the first aspect, can then be dispensed with. In this variant, the distal pump unit of the pump is firstly pulled into the distal end of the sheath lumen of the sheath according to the second aspect of the invention. Subsequently, the sheath in the sense of the second aspect is transferred for example with the help of the Seldinger technique into the natural body lumen. The sheath is then pushed into the vicinity of the operating location of the pump. The pushing is thereby effected preferably on the outside of the sheath. In order to be able to apply this method, the pump is guided via a guide wire. This can be guided for example by a guide wire lumen of the catheter tip or an additional lumen of the sheath.

(66) Conveyance of the pump to the operating location is possible in different ways. After the sheath is situated with its distal end in a natural body lumen, the pump can be guided to the operating location by pushing the shaft catheter out of the sheath and outside the latter, it must hereby be ensured that the pump unit must be pushed in the unfolded state through the natural body vessel on the basis of the absence of compression force of the sheath lumen. In this variant, a long sheath is not required.

(67) Although a possible alternative for guiding the pump unit to the operating location is present in the above-described variant, it is preferred to guide the pump in the folded or compressed state inside the sheath lumen to the vicinity of the operating location. For guidance of the sheath inside the vascular system, a rapid-exchange technique can be used, on the one hand, a guide wire being coupled for example to a possibly present catheter tip and the sheath being pushed along the guide wire. Alternatively, the sheath can include a further sheath lumen for receiving a guide wire, the sheath being pressed forwards towards the guide wire.

(68) After the distal pump unit has been pushed out of the distal end of the sheath lumen, the pump is displaced forwards merely by a small distance. The small distance in the case of the human heart as operating location of the pump is less than 20 cm. In the ratio to the total length of the long sheath, a small distance is defined by a ratio of the total length to the small distance of 3:1 or more.

(69) The sheath can remain for the period of treatment in the natural body vascular systemsurrounding the shaft catheter. In this case, the pump can be pulled into tire distal end of the sheath for explantation and subsequently, as described in one of the preceding paragraphs, be removed from the natural body vascular system.

(70) Alternatively, if the long sheath concerns a tear-off sheath, this can be withdrawn and removed after guiding the pump to the operating location. An explantation of the pump is then no longer possible by means of the sheath. An additional tool is required, which enables the explantation of the pump and forms an independently patentable subject of the invention.

(71) The additional tool is only introduced into the vascular system at the time of the explantation. The additional tool has a lumen for introducing the distal pump unit. During introduction of the additional tool, it must be ensured that no non-sterile regions of the shaft catheter are crossed. By crossing non-sterile regions, germs can be introduced into the vascular system. In order to achieve a germ-free introduction of the additional tool, it is possible to pull a portion of the shaft catheter situated in the vascular system out of the lumen since the portion formerly situated in the vessel normally has no foreign germs. The non-sterile region of the shaft catheter which lies outside the patient during use of the pump and which extends up to the drive coupling is removed for example by cutting off. The shaft catheter can also have a suitable predetermined breaking point. In this case, the additional tool can have a tubular or hose-shaped configuration and can be guided directly via the severed catheter end. A possible handle would facilitate handling.

(72) The lumen of the additional tool has an inner diameter which corresponds essentially to the outer diameter of the catheter to be explanted or to the outer diameter of the again compressed pump head. During separation of the non-sterile regions of the shaft catheter, it must hence be ensured that only components of the pump which can be inserted into such a created lumen remain distally to the distal end of the additional tool.

(73) Alternatively, the additional tool can be configured in the form of a longitudinally divisible tube. In this case, separation of the non-sterile catheter region would be unnecessary since the tool can also be placed directly on the withdrawn region.

(74) In the preceding examples, the system according to the second aspect of the invention was described such that, when the system is delivered, the sheath is situated proximally to the distal pump unit and the distal pump unit is pulled by the user of the pump into the distal end of the sheath lumen of the sheath. This has the advantage that the user can test the functional efficiency of the pump in advance. Alternatively, the system can also be delivered even already with an inserted distal pump unit. The test run of the pump then takes place at the workplace.

(75) If the pump is a self-decompressible pump, the second sheath of the system, according to the first aspect of the invention, which serves inter alia for compression of the distal pump unit, can be replaced, in a variant of the system according to the first aspect of the invention, by a crimping tool.

(76) The crimping tool has, at its distal end which is coupled to the proximal end of the first sheath, for example a diaphragm which effects compression of the distal pump unit of the pump when the distal pump unit is intended to be transferred into the first sheath. The diaphragm can be part of a funnel-shaped tapering, the diaphragm being situated at the distal end of the tapering.

(77) If a crimping tool is used, the distal pump unit is transferred by pushing into the first sheath of the system according to the first aspect of the invention.

(78) In summary, the systems according to the first, second and third aspect form independent inventions. Further variants of the invention are provided by a system according to the second aspect with a long sheath, a system according to the first aspect with a long first sheath, a system according to the first aspect with a long second sheath, a system according to the first aspect with a crimping tool, possibly instead of a second sheath. The corresponding embodiments of the system according to the first, second and third aspect can be applied likewise to the further variants of the invention.

(79) The presented treatment methods are likewise included by the invention. This relates in particular to the implantation and/or explantatlon of the pump by means of a long sheath. Also the variants of the invention cited in the preceding paragraph are suitable for implantation and/or explantation, as described in the present application.