Spiral pericardial anchor system

Abstract

A pericardial anchor for positioning a cardiac assist system over a heart of a patient underneath a sternum and ribs of the patient includes a tubular shaft, a pericardial anchor, and a removable handle. The tubular shaft has a guidewire lumen therethrough. A pericardial anchor is positioned at a distal end of the tubular shaft and a removable handle is positioned at a proximal end of the tubular shaft. The pericardial anchor is typically a spiral anchor that can be implanted to anchor in the pericardium of the patient by rotation of the handle. After the handle is removed, the tubular shaft receives and anchors the cardiac assist system over the heart of the patient located beneath the sternum and ribs of the patient.

Description

[0001] Cross-references

[0002] This application claims priority to U.S. patent application No. 63 / 350,716, filed on June 9, 2022, which is incorporated herein by reference.

[0003] The subject matter of this patent application is related to the subject matter in the following applications: U.S. patent application No. 17 / 411,928, filed on August 25, 2021; PCT application No. PCT / US2020 / 019974, filed on February 26, 2020; PCT application No. PCT / US2022 / 0751, filed on August 17, 2022; and U.S. Provisional Patent Application No. 63 / 407,100, filed on September 15, 2022, which are incorporated herein by reference.

[0004] FIELD OF THE DISCLOSURE

[0005] The present disclosure generally relates to devices and methods for placing a spiral, helical or other anchor into the pericardium to secure an intrapericardial ventricular assist device after implantation of the anchor. Clockwise rotation of the rigid spiral tip placed against the pericardium can result in limited advancement of the coil through the pericardium of slightly more than one turn. Limiting anchor advancement can be critical to avoiding injury to the lung during and after placement. Background Art

[0006] The balloon cannula can be inserted into the pericardial sac and placed in the front of the left ventricle of the heart. The inflation of the balloon during systole and the deflation of the balloon during diastole can be performed to increase the cardiac output of patients with congestive heart failure. The ventricular assist balloon cannula can be inserted through the pericardium at the lower part of the heart near the apex via a subxiphoid incision or acupuncture. The distal end of the balloon cannula can be advanced to the left side of the heart just below the left atrial appendage, thereby positioning the balloon in the front of the left ventricle. A liquid-tight reservoir can be attached to the proximal end of the balloon cannula, and the reservoir can be implanted subcutaneously in the subxiphoid region. Intrapericardial balloon inflation can be performed via a battery-driven air pump outside the patient's body. A large-caliber needle can pierce the elastic sealing surface of the patient's skin and the subcutaneous reservoir, transmitting airflow from the air supply line in the external unit to the intrapericardial balloon cannula.

[0007] As the balloon is cyclically inflated and deflated, it can be observed that the balloon cannula can move out of its position above the left ventricle and that it can deviate to the right side of the heart. This can result in loss of compression of the left ventricle and ineffective left ventricular assistance. Therefore, it may be desirable to provide an anchoring system for the tip of the balloon cannula. Additionally, it is desirable to provide an anchoring system for a ventricular assist balloon cannula that can allow replacement of the balloon cannula while retaining the favorable position established by the original anchor system. The balloon can have a limited service life; for example, one year. Providing an anchoring system that allows replacement of the balloon cannula can simplify and shorten subsequent balloon replacement procedures.

[0008] A transpericardial anchor catheter for stabilizing the distal end of an intrapericardial balloon catheter has been previously described, comprising a small diameter, non-collapsible catheter body having a short distal portion consisting of a braided sheath formed with multiple strands of polymer. A rounded tip can be attached to the distal end of the braided sheath, and a stainless steel wire can be attached to the tip, extending the length of the braided sheath and the catheter body. A section of stainless steel tubing can be bonded to the proximal portion of the catheter body, and the stainless steel tubing can extend approximately one centimeter near the proximal end of the catheter. The steel wire within the catheter can be slidably fitted with the inner diameter of the stainless steel tubing, and it can protrude several centimeters near the proximal end of the stainless steel tubing. Pulling on the stainless steel wire while the catheter remains stationary can cause the braided sheath to form an expanded disk. The braided sheath can be kept in its expanded configuration by crimping the stainless steel tubing onto the internal stainless steel wire.

[0009] Previous pericardial anchor catheters have served well as balloon catheter stabilization devices. However, their placement technique can be detrimental to the patient because the entire length of the braided sheath must typically exit the pericardial sac before the braided sheath is inflated to form an anchoring disk. The patient's lungs are very close to the pericardial sac, separated from the pericardium by several millimeters of pericardial fat and pleura that is typically less than half a millimeter thick. Braided sheath lengths may be greater than 10 mm; therefore, anchor placement can easily result in perforation of the lung surface. Summary of the invention

[0010] A pericardial anchor is proposed that involves an elongated, small-caliber stainless steel tube attached to the center of a distal unit consisting of a disk that includes a flat distal surface, wherein a helical rigid coil is circumferentially attached to the disk so that a single rotation of the helical coil extends distal to the flat surface of the disk. The distal portion of the helical coil can be located in a plane orthogonal to the axis of the tube, and the tip of the helix can include an angled undercut to form a point of pericardial entry. A removable handle can be provided on the proximal end of the stainless steel tube. The removable handle can be a guidewire twisting device clamped to the stainless steel tube, the guidewire twisting device consisting of a short plastic body pin vise.

[0011] The spiral pericardial anchor system can be inserted into the pericardial sac via an opening formed near the apex of the heart. The opening can be a pericardial incision performed via a surgical pericardial window operation. Alternatively, the pericardial sac can be entered percutaneously by passing a needle through the skin in the subxiphoid region, advancing the needle through the pericardium, passing a guide wire through the needle, removing the needle, and advancing a vascular sheath containing an internal tapered dilator over the guide wire. After removing the tapered dilator and the guide wire, the spiral pericardial anchor can be advanced into the pericardial space through the vascular sheath. In some cases, the doctor may wish to leave the guide wire in place after removing the tapered dilator and advance the spiral pericardial anchor system over the guide wire to guide the anchor system to the desired pericardial position. The pericardial anchor system can be placed in a stainless steel tube with an inner cavity, rather than a solid stainless steel wire or rod. Once the pericardial anchor system has been advanced to the desired anchor location, the guide wire can be removed from the inner cavity of the device, and the spiral tip of the device can be pressed against the pericardium using a constant force of about one pound. The helix can be rotated multiple times using the removable handle until resistance is met. At this point, one turn of the helical anchor has cleared the pericardium and the pericardium has wedged into the apex formed by the flat distal face of the disc and the exposed helical coils. Resistance felt when gently retracting the anchor system can indicate that proper placement has been achieved.

[0012] An elongated stainless steel tube extending proximally from the helical coil and support disk can contain a series of radially offset microgrooves extending half the length of the distal end and through the entire thickness of the tube. The narrow grooves are approximately 0.002" wide and they can be formed in the stainless steel tube using a laser cutter. These grooves can impart multi-directional flexibility to the portion of the tube that contacts the heart within the pericardial sac to avoid myocardial trauma that can occur when the helical anchor is implanted for a long time. Adjacent rows of circumferential microgrooves can be offset relative to the previous row to impart axial flexibility while maintaining the column strength and torsional stiffness of the tube required to apply a one pound normal force to the pericardium while rotating the helix so that its tip enters the pericardium. For most of the length of the slotted tube, adjacent slots can be spaced at uniform distances. However, the proximal and distal slotted portions may be spaced at uniform distances. The feature may be adjacent slots that increase in distance linearly as they move away from the center of the slotted portion of the tube. The increased distance between the slots may provide stress relief at the point where the rigid tube becomes flexible to avoid kinking of the tube at the connection between the solid portion and the slotted portion. The proximal portion of the stainless steel tube may comprise a solid wall, as it typically must be securely attached to the reservoir of the balloon cannula via a set screw that compresses and deforms the tube during attachment. A solid proximal portion of the stainless steel tube may be required at the reservoir attachment point to ensure proper anchoring of the balloon cannula and to avoid any possibility of anchor tube breakage during the service life of the implant.

[0013] An alternative embodiment of the device may employ a stainless steel tube having a non-circular cross section, and a long coaxial slip-fit ​​outer polymer sleeve having a similar cross-sectional profile, which is clamped to deploy the spiral anchor. The cross-sectional profile of the stainless steel tube and the corresponding cross-sectional profile of the outer sleeve keyed to the inner sleeve may be oval, square, hexagonal or other non-circular shapes. The increased profile of the outer sleeve may enable it to be used as a clamp during the placement of the spiral anchor. A flexible cover may be placed on the proximal end of the stainless steel tube to stabilize the outer polymer sleeve during the placement of the spiral anchor. After the spiral anchor is placed, the proximal cover may be slid off the stainless steel tube and the outer polymer sleeve may be removed. This embodiment does not require the use and removal of the torquer handle assembly. The removal of the torquer clamp may require the physician to apply a twisting motion of both hands, which may remove the spiral anchor from the pericardium. In this embodiment, the flexible cover is pulled axially while the outer sleeve remains stationary, thereby avoiding any twisting movement that may remove the spiral anchor.

[0014] The helical anchor can place one turn of the helix through the pericardium. The wire diameter of the helix is ​​approximately 0.022" (0.56 mm), and the depth of one turn of the helix is ​​approximately 0.056" (1.4 mm). The average thickness of the epicardial fat layer in a normal person without coronary artery disease is 4.4 + 1.2mm (Meenakshi K et al., Epicardial fat thickness: a surrogate marker of coronary artery disease: assessment by echocardiography, 2016; 68: 336-341). Therefore, one turn of the 1.4mm spiral will not protrude through the epicardial fat layer, and it will stop near the pleura surrounding the lung. Therefore, no lung damage will occur when the spiral anchor is inserted into the pericardium.

[0015] After the helical anchor is placed, the ventricular assist balloon cannula can be advanced along the stainless steel tube assembly of the anchor into position within the pericardial sac. The open through cavity can extend the entire length of the balloon, and the through cavity can accommodate the stainless steel anchor tube. After the balloon cannula is placed in place, the implantable reservoir is attached to the proximal end of the cannula. The proximal end of the stainless steel anchor tube can be inserted into a channel on the side of the reservoir housing, and a set screw extending into the channel can be tightened onto the stainless steel anchor tube to secure the balloon cannula in place during implantation.

[0016] Aspects of the present disclosure provide a pericardial anchor for positioning a heart assist system above a patient's heart below the patient's sternum and ribs. An exemplary anchor may include a tubular shaft having a guidewire lumen therethrough and a pericardial anchor at a distal end of the tubular shaft. The pericardial anchor may be configured to anchor in the patient's pericardium in response to manipulation of the tubular shaft.

[0017] In some embodiments, the pericardial anchor further comprises a removable handle at the proximal end of the tubular shaft. The pericardial anchor can be configured to anchor in the patient's pericardium in response to manipulation of the tubular shaft via the handle. The tubular shaft can be configured to receive and anchor a heart assist system above the patient's heart below the patient's sternum and ribs after the handle is removed.

[0018] In some embodiments, the pericardial anchor further comprises an extension shaft configured to be removably coupled to the proximal end of the tubular shaft. The extension shaft may have a guidewire lumen. The guidewire lumen of the extension shaft may be coaxial with the guidewire or lumen of the tubular shaft. The distal end of the extension shaft may be removably secured to the proximal end of the tubular shaft.

[0019] In some embodiments, the tubular shaft is a slotted metal tube with controlled flexibility.

[0020] In some embodiments, the pericardial anchor is a helical anchor having a flat distal face oriented in a plane orthogonal to the axis of the tubular shaft. The helical anchor can have a sharp tip configured to penetrate the pericardium into the underlying fat pad with limited penetration.

[0021] In some embodiments, the pericardial anchor further includes a polymer sleeve configured to cover the tubular shaft.

[0022] In some embodiments, manipulation of the tubular shaft comprises rotation of the tubular shaft.

[0023] Other aspects of the present disclosure also provide methods for positioning a heart assist system above a patient's heart located below the patient's sternum and ribs. An exemplary method may include the following steps: percutaneously advancing a guidewire to a position above the patient's heart located below the patient's ribs; advancing a pericardial anchor at a distal end of a tubular shaft over the guidewire to position the pericardial anchor near a preselected position on the patient's pericardium; implanting the pericardial anchor in the pericardium to stabilize the tubular shaft above the patient's heart; and advancing the heart assist system over the tubular shaft to position the heart assist system above the patient's heart located below the patient's sternum and ribs.

[0024] In some embodiments, the step of implanting the pericardial anchor into the pericardium includes rotating the shaft to implant the helical anchor into the pericardium. The helical anchor may have a flat distal face oriented in a plane orthogonal to the axis of the tubular shaft. The helical anchor may have a sharp tip configured to penetrate the pericardium into the underlying fat pad with limited penetration.

[0025] In some embodiments, a cardiac assist system includes: (i) a pneumatic effector configured to be implanted beneath a patient's pericardial sac and above a myocardial surface overlying a left ventricle of the patient; (ii) an implantable port configured to receive a percutaneously introduced cannula, wherein the port is connected to supply a driving gas received from the cannula to the pneumatic effector; (iii) an external drive unit comprising: (a) a pump assembly; and (b) a control circuit configured to operate a pump to activate the pneumatic effector in response to a sensed heart rhythm of the patient; and (iv) a connecting tube having a pump end attachable to the pump assembly and a cannula end attachable to the cannula.

[0026] In some embodiments, after the heart assist system has been advanced on the tubular shaft to position the heart assist system above the patient's heart below the patient's sternum and ribs, the heart assist system is locked in position relative to the tubular shaft to prevent one or more axial or lateral movement of the heart assist system relative to the heart. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a and Figure 1b Components comprising a helical pericardial anchor system and their assembled configuration are illustrated.

[0028] Figure 2a-2c The geometry of the distal end of the helical pericardial anchor is depicted.

[0029] Figure 3a and Figure 3b Depicted is the construction of a portion of a slotted stainless steel anchor tube.

[0030] Figure 4a-4c An alternative embodiment of a helical pericardial anchor system is depicted.

[0031] Figure 5 The location of the heart and left lung are illustrated, along with the anatomical layers of the pericardium, extrapericardial fat, and pleura in relation to the placement of the helical pericardial anchor.

[0032] Figure 6a and Figure 6b is an enlarged view depicting the insertion of the helical anchor through the pericardium.

[0033] Figure 7 The process of placing a vascular sheath over a previously placed guidewire into position within the pericardial sac is illustrated.

[0034] Figure 8 Advancement of the helical pericardial anchor system through the vascular sheath is shown to guide its placement into the pericardium.

[0035] Fig. 9 Advancement of a ventricular assist balloon catheter over a helical pericardial anchor embedded in the pericardium is shown.

[0036] Fig.10 Attachment of the proximal end of the helical pericardial anchor to the housing of a subcutaneous reservoir attached to a ventricular assist balloon catheter is shown. DETAILED DESCRIPTION

[0037] Figure 1a Describes the formation of Figure 1b Exploded view of the components of the assembled helical pericardial anchor system 10 is shown. A stainless steel helical structure 11 with a pointed distal tip can be welded to a stainless steel bushing 12, and a long stainless steel tube 13 can be attached to the center of the bushing 12. The helical structure 11 can be formed from 316 stainless steel with a wire diameter of approximately 0.022", and its outer diameter measuring approximately 0.180". The stainless steel tube 13 can have an outer diameter of 0.050" and a wall thickness of 0.005", so that its inner lumen can accommodate a 0.038" guidewire. A guidewire twisting device 14 can be fastened to the proximal end of the stainless steel tube 13 to serve as a handle to facilitate rotation of the helical pericardial anchor 10 during placement in the pericardium. The guidewire twisting device 14 is Figure 1a , Figure 1b 13. The stainless steel tube 13 is shown as a (clampable) block. Alternatively or in combination, the proximal end of the stainless steel tube 13 can be fastened to the distal end of another stainless steel tube to elongate or extend the stainless steel tube 13. In some cases, the additional stainless steel tube can be used as a guide wire twisting device 14. In some cases, a separate guide wire twisting device 14 can be fastened to the proximal end of the additional stainless steel tube. The additional stainless steel tube can have an inner guide wire lumen, which is configured to also be coaxial with the lumen of the stainless steel tube 13.

[0038] Figure 2a The configuration of the helix 11 is shown when attached to the bushing 12. A single turn of the helix 11 may extend distal to the flat distal face of the bushing 12. Figure 2b The configuration of the pointed distal tip of the helix 11 is shown, which is formed by grinding an angle on the inside of the wire tip. The distal tip can be formed using an angled undercut of the wire so that the distal portion of the helix 11 lies in a plane orthogonal to the axis of the helical anchor system 10, as shown in FIG. Figure 2c shown.

[0039] Figure 3 depicts the construction of a stainless steel tube 13 having microgrooves 15 formed on opposite sides of its wall. The grooves 15 may be invisible to the naked eye and have a width of 0.002" and a length extending 70% of the 0.050" diameter of the stainless steel tube 13 (equal to 0.035"). A distance of 0.015" may separate adjacent axial grooves 15. The adjacent grooves 15 are radially offset from the previous set of grooves 15 by a distance equal to 20% of the length of the groove 15, or 0.035". The grooves 15 can extend half of the distal length of the stainless steel tube 13. They can impart flexibility to the portion of the stainless steel tube 13 that is located within the pericardial sac and in contact with the heart. This flexibility can be critical to avoiding trauma to the heart during insertion of the helical pericardial anchor and during long-term implantation. Excessive rigidity of the stainless steel tube 13 can cause tearing or perforation of the heart during insertion of the helical anchor, as well as potential myocardial tearing during long-term implantation. The radially offset series of grooves 15 can provide flexibility in all directions to the distal stainless steel tube 13 without sacrificing the column strength or torsional strength required when the pericardial anchor applies approximately one pound of force to the pericardium and then rotates to achieve pericardial entry and proper anchoring.

[0040] Figure 4a Depicted are the internal components of an alternative embodiment of the helical pericardial anchor system 10, including the helix 11, the bushing 12, and the stainless steel tube 13. In this embodiment, the stainless steel tube 13 comprises a non-circular cross-sectional profile, such as a square. Figure 4b A telescoping slip-fit ​​polymer sleeve 16 is shown fitted over a non-circular stainless steel tube 13. The polymer sleeve 16 may contain an inner lumen that matches the outer contour of the non-circular stainless steel tube 13, and it may be slightly shorter than the stainless steel tube 13 in length. Figure 4c It is shown that a flexible end cap 17 can be placed on the exposed proximal end of the stainless steel tube 13 to stabilize the polymer sleeve 16 when grasping and rotating the polymer sleeve 16 to insert the anchor system 10 into the pericardium. The proximal portion of the polymer sleeve 16 can be used as a handle for the insertion of the spiral anchor 11. After the anchor 11 is inserted, the polymer sleeve 16 can remain stationary when the end cap 17 is removed from the stainless steel tube 13. An advantage of this embodiment can be that it does not require a gripper like Figure 1b The twisting motion as in the illustrated embodiment can be used to remove the attached twisting device 14. The two-hand twisting required to remove the twisting device 14 may dislodge the spiral 11 from the pericardium. Removing the end cap 17 may involve an axial motion that is less likely to dislodge the fixed spiral 11.

[0041] Figure 5 The heart 18 and left lung 22 are depicted within the chest cavity. The heart 18 is surrounded by the pericardial sac 19. The pericardial fat pad 20 is located outside the pericardium 19, and the fibrous pleura 21 surrounds the lung 22. The pleura 21 is in contact with the pericardial fat pad 20.

[0042] Figure 6a The spiral 11 is shown positioned in preparation for insertion into the pericardium 19. The extrapericardial fat pad 20, pleura 21, and lungs 22 are located outside the pericardium 19. The spiral 11 can be advanced with slight force (approximately 1 pound of force) to contact the pericardium 19 and the spiral 11 can be rotated two to three times using the twist handle 14 until resistance is felt, indicating that one turn of the spiral 11 has entered the pericardium 19 and the pericardium 19 is close to the distal surface of the sleeve 12, as shown in FIG. Figure 6b As shown. The average thickness of the human pericardium is 1.02 mm (Lee JM, Mechanical properties of human pericardium, Circ Res Circ Res 1985; 55: 475), and the thickness of the pericardial fat pad is about 4.4 mm. Therefore, the tip of the spiral 11 will not enter the pleura 21 or the lung 22 when placed, thereby avoiding the possibility of perforation or tearing of the lung 22.

[0043] Figure 7 Depicted is the positioning of a vascular sheath 24 within the pericardial sac 19 on the left lateral aspect of the heart 18 in preparation for placement of a helical anchor catheter. The vascular sheath 24 may be advanced over a previously placed guidewire 23 inserted via a needle puncture into the pericardium 19 on the inferior portion of the heart 18. Positioning of the guidewire 23 and vascular sheath 24 may be performed under fluoroscopic x-ray guidance.

[0044] Figure 8 The helical anchor catheter 10 is shown advanced through a vascular sheath 24 located at the left edge of the pericardial sac 19. As the helical anchor catheter 10 is rotated to achieve placement through the pericardium 19, the vascular sheath 24 may remain stationary.

[0045] Fig. 9 The ventricular assist balloon cannula 25 is shown being advanced along the axis of the helical anchor catheter 10 after the helix 11 has been secured to the pericardium 19. The ventricular assist balloon can be a component of a ventricular assist device, as described in related U.S. Patent Application No. 17 / 411,928 (filed on August 25, 2021), PCT Application No. PCT / US2020 / 019974 (filed on February 26, 2020), PCT / US2022 / 0751 (filed on August 17, 2022), and U.S. Provisional Patent Application No. 63 / 407,100 (filed on September 15, 2022), which are incorporated herein by reference.

[0046] Fig.10It is shown that after the ventricular assist balloon catheter 25 is advanced over the helical anchor catheter 10, a subcutaneous reservoir 26 can be attached to the proximal end of the ventricular assist balloon catheter 25, and the proximal end of the helical anchor catheter 10 can be inserted into a channel in the housing of the subcutaneous reservoir 26, where it is locked in place using a set screw 27. The helix 11 embedded in the pericardium 19 and the set screw 27 that secures the proximal helical anchor catheter 10 to the reservoir 26 can prevent axial and lateral movement of the ventricular assist balloon catheter 25 relative to the heart 18.

[0047] Although preferred embodiments of the present disclosure have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. The disclosure is not intended to be limited by the specific examples provided in the specification. Although the disclosure has been described with reference to the above description, the description and illustration of the embodiments herein are not intended to be interpreted in a limiting sense. Without departing from the disclosure, many variations, changes and substitutions can now be conceived by those skilled in the art. In addition, it should be understood that all aspects of the disclosure are not limited to the specific description, configuration or relative proportion depending on various conditions and variables set forth herein. It should be understood that in practicing the disclosure, various alternatives to the embodiments of the disclosure described herein may be adopted. Therefore, it is contemplated that the present invention should also encompass any such alternatives, modifications, variations or equivalents. The appended claims are intended to define the scope of the disclosure, and thus encompass methods and structures and their equivalents within the scope of these claims.

Claims

1. A pericardial anchor for positioning a cardiac assist system above a patient's heart below the patient's sternum and ribs, the pericardial anchor comprising: a tubular shaft having a guidewire lumen extending therethrough; as well as a pericardial anchor located at the distal end of the tubular shaft; The pericardial anchor is configured to anchor in the patient's pericardium in response to manipulation of the tubular shaft.

2. The pericardial anchor of claim 1, further comprising a removable handle at the proximal end of the tubular shaft.

3. The pericardial anchor of claim 2, wherein the pericardial anchor is configured to anchor in the patient's pericardium in response to manipulation of the tubular shaft via the handle.

4. The pericardial anchor of claim 2 or 3, wherein the tubular shaft is configured to receive and anchor the heart assist system above the patient's heart below the patient's sternum and ribs after removal of the handle.

5. The pericardial anchor of any one of claims 1 to 4, further comprising an elongated shaft configured to be removably coupled to the proximal end of the tubular shaft.

6. The pericardial anchor of claim 5, wherein the elongate shaft has a guidewire lumen.

7. The pericardial anchor of any one of claims 1 to 6, wherein the tubular shaft is a slotted metal tube with controlled flexibility.

8. The pericardial anchor of any one of claims 1 to 7, wherein the pericardial anchor is a helical anchor having a flat distal face oriented in a plane orthogonal to the axis of the tubular shaft, wherein the helical anchor has a sharp tip configured to penetrate the pericardium into the underlying fat pad with limited penetration force.

9. The pericardial anchor of any one of claims 1 to 8, further comprising a polymer sleeve configured to cover the tubular shaft.

10. The pericardial anchor of any one of claims 1 to 9, wherein the manipulation of the tubular shaft comprises rotation of the tubular shaft.

11. A method for positioning a heart assist system over a patient's heart below the patient's sternum and ribs, the method comprising: percutaneously advancing a guidewire to a position above the patient's heart below the patient's ribs; advancing a pericardial anchor at the distal end of the tubular shaft over the guidewire to position the pericardial anchor proximate a preselected location on the patient's pericardium; implanting the pericardial anchor in the pericardium to stabilize the tubular shaft over the patient's heart; as well as The heart assist system is advanced over the tubular shaft to position the heart assist system over the patient's heart beneath the patient's sternum and ribs.

12. The method of claim 11, wherein implanting the pericardial anchor in the pericardium comprises rotating the shaft to implant a helical anchor in the pericardium.

13. The method of claim 12, wherein the helical anchor has a flat distal face oriented in a plane orthogonal to the axis of the tubular shaft, wherein the helical anchor has a sharp tip configured to penetrate the pericardium into the underlying fat pad with limited penetration.

14. The method according to any one of claims 11 to 13, wherein the heart assist system comprises: a pneumatic effector configured to be implanted beneath a pericardial sac of a patient and above a surface of a myocardium overlying a left ventricle of the patient; an implantable port configured to receive a percutaneously introduced cannula, wherein the port is connected to supply a drive gas received from the cannula to the pneumatic effector; An external drive unit, the external drive unit comprising: (a) pump assemblies; and (b) a control circuit configured to operate the pump to activate the pneumatic effector in response to a sensed heart rhythm of the patient; and A connecting tube having a pump end attachable to the pump assembly and a cannula end attachable to the cannula.

15. The method according to any one of claims 11 to 14 further includes locking the heart assist system in an appropriate position relative to the tubular shaft after the heart assist system has been advanced on the tubular shaft to position the heart assist system above the patient's heart below the patient's sternum and ribs to prevent one or more axial or lateral movements of the heart assist system relative to the heart.

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