Distal tip element for a ventricular assist device
Apparatus and methods are described including a left-ventricular assist device that includes a tube configured to traverse a subject's aortic valve, with a distal portion of the tube disposed within the subject's left ventricle. A frame is disposed within the distal portion of the tube. A pump disposed within the frame pumps blood through the tube. A distal-tip element defines a straight proximal portion that defines a longitudinal axis, and a curved distal portion that is shaped such as to curve in a first direction with respect to the longitudinal axis before passing through an inflection point and curving in a second direction with respect to the longitudinal axis, such that the curved distal portion defines a bulge on one side of the longitudinal axis. Other applications are also described.
1. Apparatus comprising:
a left-ventricular assist device configured to assist left-ventricular functioning of a subject, the left-ventricular assist device comprising:
a tube configured such that a proximal portion of the tube traverses an aortic valve of the subject, and a distal portion of the tube is disposed within a left ventricle of the subject;
a frame disposed within at least the distal portion of the tube;
a pump disposed within the frame and configured to pump blood through the tube from the subject's left ventricle to the subject's aorta, by pumping the blood into the tube via at least one blood inlet opening that is defined by the tube and that is configured to be disposed within the subject's left ventricle, and by pumping blood out of the tube via at least one blood outlet opening that is defined by the tube and that is configured to be disposed within the subject's aorta; and
a distal-tip element configured to define a straight proximal portion that defines a longitudinal axis, and a curved distal portion that is shaped such as to curve in a first direction with respect to the longitudinal axis of the straight proximal portion before passing through an inflection point and curving in a second direction with respect to the longitudinal axis of the straight proximal portion, such that the curved distal portion defines a bulge on one side of the longitudinal axis of the straight proximal portion.
2. The apparatus according to claim 1 , wherein the distal-tip element is configured to separate the at least one blood inlet opening from a posterior wall of the subject's left ventricle when the distal-tip element is placed against an apex of the subject's left ventricle.
3. The apparatus according to claim 1 , wherein the distal-tip element has a question-mark shape.
4. The apparatus according to claim 1 , wherein the distal-tip element has a tennis-racket shape.
5. The apparatus according to claim 1 , wherein the curved distal portion of the distal-tip element is shaped such that after passing through the inflection point the curved distal portion continues to curve such that the distal-tip portion crosses back over the longitudinal axis defined by the straight proximal portion.
6. The apparatus according to claim 1 , wherein the curved distal portion of the distal-tip element is shaped such that after passing through the inflection point the curved distal portion does not cross back over the longitudinal axis defined by the straight proximal portion.
7. The apparatus according to claim 1 , wherein the blood pump comprises an impeller disposed on an axial shaft, and wherein the distal-tip element comprises an axial-shaft receiving tube configured to receive the axial shaft of the blood pump, and a distal-tip portion configured to define the curved distal portion of the distal-tip element.
8. The apparatus according to claim 1 , wherein the distal-tip element is configured to separate the at least one blood inlet opening from a septal wall of the subject's left ventricle as the distal-tip element contacts an apex of the subject's left ventricle.
9. The apparatus according to claim 8 , wherein the distal-tip element is configured such that, when distal-tip element is inserted into the left ventricle such that the bulge bulges toward the septal wall, in response to the distal-tip element being pushed against the apex of the subject's left ventricle, the blood inlet opening gets pushed away from the septal wall and toward a free wall of the subject's left ventricle.
10. The apparatus according to claim 9 , wherein the distal-tip element is configured such that, in response to the distal-tip element being pushed against the apex of the subject's left ventricle, the blood inlet opening gets pushed away from the septal wall and toward the free wall of the subject's left ventricle by the straight proximal portion of the distal-tip element pivoting about the curved distal portion of the distal-tip element.
11. The apparatus according to claim 1 , wherein the distal-tip element is configured such that, upon being deployed within a descending aorta of the subject, the distal-tip element centers itself with respect to an aortic valve of the subject.
12. The apparatus according to claim 11 , wherein the curved distal portion is shaped that after curving in the first direction the curved distal portion defines an elongated straight portion, before curving the in the second direction, such that the elongated straight portion protrudes at an angle with respect to the longitudinal axis of the proximal straight portion of the distal-tip element.
13. The apparatus according to claim 1 , wherein a duckbill valve is disposed within a distal-most 10 mm of the distal-tip element.
14. The apparatus according to claim 13 , wherein the duckbill valve defines a wide inlet and a narrow tip that defines a slit therethrough, the duckbill valve being proximally facing, such that the wide inlet faces a distal end of the distal-tip element and such that the narrow tip faces away from the distal end of the distal-tip element.
15. The apparatus according to claim 14 , wherein:
the left-ventricular assist device is configured for use with a guidewire;
the distal-tip element defines a guidewire lumen; and
the left-ventricular assist device further comprises a guidewire guide disposed within the guidewire lumen at a location that is proximal to the duckbill valve, the guidewire guide shaped to define a hole therethrough, which narrows in diameter from a proximal end of the guidewire guide to a distal end of the guidewire guide, the shape of the guidewire guide being configured to guide a tip of the guidewire toward the slit at the narrow, proximal end of the duckbill valve, when the guidewire is inserted from a proximal end of the left-ventricular assist device.
16. The apparatus according to claim 15 , wherein the duckbill valve is shaped to define a converging guide portion at its proximal end, the converging guide portion converging toward the slit, such that the guide portion is configured to further guide the tip of the guidewire toward the slit.