Abstract
A pericardial anchor for positioning a cardiac assist system over a patient's heart beneath the patient's sternum and ribs includes a tubular shaft, a pericardial anchor, and a removable handle. The tubular shaft has a guidewire lumen therethrough. The pericardial anchor is positioned at a distal end of the tubular shaft, and the removable handle is positioned at a proximal end of the tubular shaft. The pericardial anchor is typically a helical anchor that can be implanted to anchor in the patient's pericardium by rotation of the handle. The tubular shaft receives and anchors a cardiac assist system over the patient's heart beneath the patient's sternum and ribs after the handle is removed.
Claims
1. A pericardial anchor for positioning a cardiac assist system over a patient's heart beneath the patient's sternum and ribs, said pericardial anchor comprising: a tubular shaft having a guidewire lumen therethrough; and a pericardial anchor at a distal end of the tubular shaft; wherein 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 a 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, wherein the tubular shaft is configured to receive and anchor the cardiac assist system over the patient's heart beneath the patient's sternum and ribs after the handle is removed.
5. The pericardial anchor of claim 1, further comprising an extension shaft configured to removably couple to the proximal end of the tubular shaft.
6. The pericardial anchor of claim 5, wherein the extension shaft has a guidewire lumen.
7. The pericardial anchor of claim 1, wherein the tubular shaft is a slotted metal tube having controlled flexibility.
8. The pericardial anchor of claim 1, wherein the pericardial anchor is a helical anchor with a flat distal face oriented in a plane orthogonal to an axis of the tubular shaft, wherein the helical anchor has a sharpened tip configured to penetrate a pericardial membrane with limited penetration into an underlying fat pad.
9. The pericardial anchor of claim 1, further comprising a polymer sleeve configured to cover the tubular shaft.
10. The pericardial anchor of claim 1, wherein the manipulation of the tubular shaft comprises rotation of the tubular shaft.
11. A method for positioning a cardiac assist system over a patient's heart beneath the patient's sternum and ribs, said method comprising: percutaneously advancing a guidewire to a position over the patient's heart beneath the patient's ribs; advancing a pericardial anchor at a distal end of a tubular shaft over the guidewire to position the pericardial anchor adjacent 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; and advancing the cardiac assist system over the tubular shaft to locate the cardiac 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 an axis of the tubular shaft, wherein the helical anchor has a sharpened tip configured to penetrate a pericardial membrane with limited penetration into an underlying fat pad.
14. The method of claim 11, wherein the cardiac assist system comprises: a pneumatic effector configured to be implanted beneath a patient's pericardial sac and over a myocardial surface overlying the patient's left ventricle; an implantable port configured to receive a percutaneously introduced cannula, wherein said port is connected to supply a driving gas received from the cannula to the pneumatic effector; an external drive unit including: (a) a pump assembly; and (b) control circuitry configured to operate the pump to actuate the pneumatic effector in response to the patient's sensed heart rhythm; and a connecting tube having a pump end attachable to the pump assembly and a cannula end attached to the cannula.
15. The method of claim 11, further comprising locking the cardiac assist system in position with respect to the tubular shaft to prevent one or more of axial or transverse movement of the cardiac assist system with respect to the heart after the cardiac assist system has been advanced over the tubular shaft to locate the cardiac assist system over the patient's heart beneath the patient's sternum and ribs.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIGS. 1a and 1b illustrate the components comprising the spiral pericardial anchor system and its assembled configuration.
[0026] FIGS. 2a-2c depict the geometric configuration of the distal end of the spiral pericardial anchor.
[0027] FIGS. 3a and 3b depict the configuration of the partially slotted stainless steel anchor tube.
[0028] FIGS. 4a-4c depict an alternate embodiment of a spiral pericardial anchor system.
[0029] FIG. 5 illustrates the position of the heart and the left lung, and the anatomical layers of pericardium, extra-pericardial fat, and pleura pertinent to spiral pericardial anchor placement.
[0030] FIGS. 6a and 6b are magnified views depicting the process of spiral anchor insertion through the pericardial membrane.
[0031] FIG. 7 illustrates the process of vascular sheath placement into position inside the pericardial sac over a previously placed guidewire.
[0032] FIG. 8 shows the advancement of the spiral pericardial anchor system through a vascular sheath to guide its placement into the pericardial membrane.
[0033] FIG. 9 shows advancement of the ventricular assist balloon cannula over the spiral pericardial anchor embedded in the pericardial membrane.
[0034] FIG. 10 shows attachment of the proximal end of the spiral pericardial anchor to the housing of the subcutaneous reservoir attached to the ventricular assist balloon cannula.
DETAILED DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1a depicts an exploded view of the components that form the spiral pericardial anchor system 10 as shown assembled in FIG. 1b. A stainless-steel spiral form 11 with a pointed distal tip may be welded to a stainless-steel bushing 12, and a long stainless-steel tube 13 may be attached to the center of the bushing 12. Spiral structure 11 may be formed of 316 stainless steel, with a wire diameter of approximately 0.022 and an outer diameter measuring approximately 0.180. The stainless-steel tube 13 may have an outer diameter of 0.050 and a wall thickness of 0.005, such that its inner lumen may accommodate a 0.038 guidewire. A guidewire torque device 14 may be fastened onto the proximal end of the stainless-steel tube 13 to serve as a handle to facilitate rotation of the spiral pericardial anchor 10 during its placement in the pericardium. The guidewire torque device 14 is shown as a (graspable) block in FIGS. 1a, 1b. Alternatively or in combination, the proximal end of the stainless-steel tube 13 may be fastened onto the distal end of another stainless-steel tube so as to elongate or extend the stainless-steel tube 13. In some cases, the additional stainless-steel tube may be used as the guidewire torque device 14. In some cases, a separate guidewire torque device 14 may be fastened on to the proximal end of the additional stainless-steel tube. The additional stainless-steel tube may have an inner guidewire lumen configured to be coaxial with the inner lumen of the stainless-steel tube 13 as well.
[0036] FIG. 2a illustrates the configuration of the spiral 11 as it is attached to the bushing 12. A single revolution of spiral 11 can extend distal to the flat distal face of bushing 12. FIG. 2b shows the configuration of the pointed distal tip of spiral 11, formed by grinding an angle on the inner aspect of the wire tip. An angled undercut of the wire may be used to form the distal tip, such that the distal portion of spiral 11 lies in a flat plane orthogonal to the axis of the spiral anchor system 10, as illustrated in FIG. 2c.
[0037] FIG. 3 depicts the configuration of the stainless-steel tube 13, with microscopic slots 15 formed on opposing sides of its wall. The slots 15 may be invisible to the naked eye, at 0.002 in width, with a length that extends 70% of the 0.050 diameter of the stainless-steel tube 13, equal to 0.035. A distance of 0.015 can separate adjacent axial slots 15. Adjacent slots 15 are radially offset from the previous set of slots 15 by a distance equal to 20% of the length of the slot 15, or 0.035. The slots 15 may extend one half of the distal length of stainless-steel tube 13. They may impart flexibility to the portion of the stainless-steel tube 13 that lies inside the pericardial sac in contact with the heart. This flexibility may be essential in avoiding trauma to the heart during insertion of the spiral pericardial anchor and upon long term implantation. Excessive rigidity of the stainless-steel tube 13 may cause laceration or perforation of the heart during spiral anchor insertion, as well as potential myocardial laceration during long term implantation. The radially offset series of slots 15 can provide flexibility of the distal stainless-steel tube 13 in all directions without sacrificing the column strength or torsional strength required as the pericardial anchor exerts approximately one pound of force against the pericardium followed by its rotation to achieve pericardial entry and proper anchoring.
[0038] FIG. 4a depicts the inner components of an alternate embodiment of a spiral pericardial anchor system 10, comprising of a spiral 11, a bushing 12, and a stainless-steel tube 13. In this embodiment, the stainless-steel tube 13 contains an off-round cross-sectional profile such as a square. FIG. 4b shows that a telescoping, slip-fit polymer sleeve 16 fits over off-round stainless-steel tube 13. The polymer sleeve 16 may contain an inner lumen that matches the outer profile of the off-round stainless-steel tube 13, and it may be slightly shorter in length than stainless steel tube 13. FIG. 4c shows that a flexible end cap 17 may be placed on the exposed proximal end of stainless-steel tube 13 to stabilize polymer sleeve 16 as it is grasped and rotated to insert the anchor system 10 in the pericardium. The proximal portion of polymer sleeve 16 may function as the handle for spiral anchor 11 insertion. Following anchor 11 insertion, the polymer sleeve 16 can be held stationary as the end cap 17 is removed from the stainless-steel tube 13. An advantage of this embodiment may be that it does not require a twisting motion for removal of an attached torque device 14 as in the embodiment shown in FIG. 1b. Two-handed twisting required for removal of torque device 14 may dislodge the spiral 11 from the pericardium. Removal of end cap 17 can involve an axial motion that is less likely to dislodge a fixated spiral 11.
[0039] FIG. 5 depicts the heart 18 and left lung 22 in the thoracic cavity. The heart 18 is enclosed by the pericardial sac 19. A pericardial fat pad 20 lies outside of the pericardium 19, and a fibrous pleural membrane 21 encloses the lung 22. The pleura 21 is in contact with the pericardial fat pad 20.
[0040] FIG. 6a shows the positioning of the spiral 11 in preparation for insertion into pericardial membrane 19. The extra-pericardial fat pad 20, pleura 21 and lung 22 lie outside of pericardial membrane 19. The spiral 11 may be advanced to be in contact with the pericardial membrane 19 with a mild amount of force, approximately 1 pound of force, and rotated two to three revolutions using the torque handle 14, until resistance is felt, indicating that one revolution of spiral 11 has entered pericardial membrane 19, and pericardial membrane 19 is abutted against the distal face of bushing 12, as seen in FIG. 6b. Human pericardium has a mean thickness of 1.02 mm (Lee J M. Mechanical properties of human pericardium. Circ Res 1985; 55:475), and the pericardial fat pad is approximately 4.4 mm thick. Therefore, the tip of spiral 11 upon placement does not enter the pleura 21 or the lung 22, avoiding potential for perforation or laceration of the lung 22.
[0041] FIG. 7 depicts the positioning of vascular sheath 24 inside the pericardial sac 19 on the left lateral aspect of the heart 18, in preparation for placement of the spiral anchor catheter. Vascular sheath 24 may be advanced over a previously placed guidewire 23 inserted via a needle puncture in the pericardium 19 on the inferior aspect of the heart 18. Positioning of the guidewire 23 and the vascular sheath 24 may be performed under fluoroscopic x-ray guidance.
[0042] FIG. 8 shows advancement of the spiral anchor catheter 10 through the vascular sheath 24 positioned at the left lateral border of the pericardial sac 19. Vascular sheath 24 can be held stationary as spiral anchor catheter 10 is rotated to achieve placement through pericardium 19.
[0043] FIG. 9 shows advancement of the ventricular assist balloon cannula 25 along the shaft of spiral anchor catheter 10 after the spiral 11 has been fixated to the pericardial membrane 19. The ventricular assist balloon may be a component of a ventricular assist device as described in related U.S. patent application Ser. No. 17/411,928, filed Aug. 25, 2021, PCT Application No. PCT/US2020/019974, filed Feb. 26, 2020, PCT/US2022/0751, filed Aug. 17, 2022, and U.S. Provisional Patent Application No. 63/407,100, filed Sep. 15, 2022, which are incorporated herein by reference.
[0044] FIG. 10 shows that following advancement of ventricular assist balloon cannula 25 over spiral anchor catheter 10, a subcutaneous reservoir 26 may be attached to the proximal end of ventricular assist balloon cannula 25, and the proximal end of spiral anchor catheter 10 may be inserted into a channel in the housing of subcutaneous reservoir 26, where it is locked in position using a setscrew 27. The spiral 11 embedded in the pericardium 19 and the setscrew 27 fixation of the proximal spiral anchor catheter 10 to the reservoir 26 can prevent axial and transverse movement of the ventricular assist balloon cannula 25 with respect to the heart 18.
[0045] While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the disclosure be limited by the specific examples provided within the specification. While the disclosure has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the disclosure. Furthermore, it shall be understood that all aspects of the disclosure are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the disclosure described herein may be employed in practicing the disclosure. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the disclosure and that methods and structures within the scope of these claims and their equivalents be covered thereby.
