Ventricular assist device

Abstract

Apparatus and methods are described including a left-ventricular assist device including an impeller and a frame disposed around the impeller. A pump-outlet tube traverses the subject's aortic valve with a distal portion of the pump-outlet tube disposed within the subject's left ventricle. The distal portion of the pump-outlet tube extends to a distal end of the frame and defines more than 10 blood-inlet openings that are sized such as (a) to allow blood to flow from the subject's left ventricle into the tube and (b) to block structures from the subject's left ventricle from entering into the frame. The porosity of the distal portion of the pump-outlet tube is lower within a proximal region of the distal portion of the pump-outlet tube than within a distal region of the distal portion of the pump-outlet tube that is distal to the proximal region. Other applications are also described.

1 . An apparatus, comprising:
 a left-ventricular assist device comprising:
 an impeller configured to be placed inside a left ventricle of a subject and to pump blood from the left ventricle to an aorta of the subject, by rotating; 
 a frame disposed around the impeller; and 
 a pump-outlet tube configured to traverse an aortic valve of the subject, such that a proximal portion of the tube is disposed within the subject's aorta and a distal portion of the pump-outlet tube is disposed within the subject's left ventricle, 
 the distal portion of the pump-outlet tube extending to a distal end of the frame and defining more than 10 blood-inlet openings that are sized such as (a) to allow blood to flow from the subject's left ventricle into the tube and (b) to block structures from the subject's left ventricle from entering into the frame, 
 wherein a porosity of the distal portion of the pump-outlet tube, which defines the blood-inlet openings, is lower within a proximal region of the distal portion of the pump-outlet tube than within a distal region of the distal portion of the pump-outlet tube that is distal to the proximal region. 
   
     
     
         2 . The apparatus according to  claim 1 , wherein each of the blood-inlet openings is shaped such that, in at least one direction, a width of the opening is less than 1 mm. 
     
     
         3 . The apparatus according to  claim 1 , wherein a ratio of the porosity of the distal portion of the pump-outlet tube within the distal region to the porosity of the distal portion of the pump-outlet tube within the proximal region is more than 4:3. 
     
     
         4 . The apparatus according to  claim 1 , wherein the porosity of the distal portion of the pump-outlet tube is varied between the proximal region and the distal region such as to account for varying blood flow dynamics at different regions of the distal portion of the pump-outlet tube. 
     
     
         5 . The apparatus according to  claim 1 , wherein the distal portion of the pump-outlet tube is conical, and wherein the porosity of the distal portion of the pump-outlet tube is varied between the proximal region and the distal region such as to account for changes in the shape of the distal conical portion along its length. 
     
     
         6 . The apparatus according to  claim 1 , wherein along the distal region of the distal portion of the pump-outlet tube, the pump-outlet tube defines large blood-inlet openings that are configured to reduce a risk of thrombosis relative to if the blood-inlet openings along the distal region of the distal conical portion of the pump-outlet tube were smaller. 
     
     
         7 . The apparatus according to  claim 1 , wherein the distal portion of the pump-outlet tube defines more than 50 blood-inlet openings that are sized such as (a) to allow blood to flow from the subject's left ventricle into the tube and (b) to block structures from the subject's left ventricle from entering into the frame. 
     
     
         8 . The apparatus according to  claim 1 , wherein the blood-inlet openings are rectangular and are shaped such that a ratio of lengths to widths of each of the blood-inlet openings is between 1.1:1 and 4:1. 
     
     
         9 . The apparatus according to  claim 1 , wherein the blood inlet openings are rectangular and are shaped such that a ratio of lengths to widths of each of the blood-inlet openings is between 3:2 and 5:2. 
     
     
         10 . The apparatus according to  claim 1 , wherein the distal portion of the pump-outlet tube has a porosity of more than 40 percent. 
     
     
         11 . The apparatus according to  claim 10 , wherein the distal portion of the pump-outlet tube has a porosity of more than 50 percent. 
     
     
         12 . The apparatus according to  claim 11 , wherein the distal portion of the pump-outlet tube has a porosity of more than 60 percent. 
     
     
         13 . The apparatus according to  claim 1 , wherein the frame defines a central cylindrical portion and a distal conical portion, wherein the distal portion of the pump-outlet tube, which defines the blood-inlet openings, is conical and is disposed over the distal conical portion of the frame, and wherein a portion of the pump-outlet tube that is proximal to the distal portion of the pump-outlet tube is coupled to the central cylindrical portion of the frame. 
     
     
         14 . The apparatus according to  claim 13 , wherein the portion of the pump-outlet tube that is proximal to the distal portion of the pump-outlet tube is coupled to the central cylindrical portion of the frame via heating, and wherein the porosity is lower is within the proximal region of the distal portion of the pump-outlet tube, such that damage that may be caused to a material that defines the blood-inlet holes within the proximal region of the distal portion of the pump-outlet tube is reduced during the heating relative to if the porosity within the proximal region of the distal portion of the pump-outlet tube was higher. 
     
     
         15 . The apparatus according to  claim 13 , further comprising an inner lining coupled to an inner surface of the central cylindrical portion of the frame, such that the inner lining provides the central cylindrical portion of the frame with a smooth inner surface. 
     
     
         16 . The apparatus according to  claim 13 , wherein the proximal region of the distal portion of the pump-outlet tube extends along a length of 0.5-2 mm. 
     
     
         17 . The apparatus according to  claim 1 , wherein the blood-inlet openings have polygonal shapes. 
     
     
         18 . The apparatus according to  claim 17 , wherein the blood-inlet openings have hexagonal shapes. 
     
     
         19 . The apparatus according to  claim 17 , wherein, within the proximal region of the distal portion of the pump-outlet tube, a diameter of a circle enclosed by each of the blood-inlet openings is between 0.1 and 0.6 mm. 
     
     
         20 . The apparatus according to  claim 17 , wherein, within the proximal region of the distal portion of the pump-outlet tube, widths of gaps between adjacent blood-inlet openings are between 0.05 and 0.2 mm. 
     
     
         21 . The apparatus according to  claim 17 , wherein, within the distal region of the distal portion of the pump-outlet tube, a diameter of a circle enclosed by each of the blood-inlet openings is between 0.2 and 0.8 mm. 
     
     
         22 . The apparatus according to  claim 17 , wherein, within the distal region of the distal portion of the pump-outlet tube, widths of gaps between adjacent blood-inlet openings are between 0.01 mm and 0.1 mm. 
     
     
         23 . The apparatus according to  claim 17 , wherein a ratio of a diameter of a circle enclosed by each the blood-inlet openings with the distal region of the distal portion of the pump-outlet tube to a diameter of a circle enclosed by each of the blood-inlet openings with the proximal region of the distal portion of the pump-outlet tube is greater than 7:6. 
     
     
         24 . The apparatus according to  claim 17 , wherein a ratio of widths of gaps between adjacent blood-inlet openings with the proximal region of the proximal portion of the pump-outlet tube to widths of gaps between adjacent blood-inlet openings within the distal region of the distal portion of the pump-outlet tube is greater than 3:2.