Atherectomy device supported by fluid bearings

Abstract

A rotational atherectomy device for removing a stenotic tissue from a vessel of a patient comprises a flexible hollow drive shaft and an abrasive element mounted to the drive shaft proximal to and spaced from a solid support element mounted at the distal end of the drive shaft, the solid support element having a rounded outer surface and an outflow channel with an outflow opening in said rounded outer surface. The drive shaft comprises a torque transmitting coil and at least one fluid impermeable membrane forming a fluid impermeable lumen for the antegrade flow of fluid into the outflow channel such that, during rotation of the drive shaft, a flow of fluid out of said outflow opening forms a fluid bearing between the rotating solid support element and the wall of the treated vessel.

1 . A method of using a rotational atherectomy device comprising:
 delivering a distal end portion of a rotational atherectomy device to a blood vessel having a stenotic lesion to be treated, the rotational atherectomy device including a rotatable, flexible drive shaft comprising a longitudinal axis, a torque transmitting coil, and at least one fluid delivery lumen extending to the distal end portion of rotational atherectomy device;   rotating the drive shaft of the rotational atherectomy device so that an abrasive element mounted to the drive shaft along distal end portion of the rotational atherectomy device rotates with the vessel having the stenotic lesion to be treated, wherein a center of mass of the abrasive element is offset from the longitudinal axis of the drive shaft; and   during rotation of the drive shaft, outputting fluid flow in a generally radially outward direction through outflow ports in each of a distal solid counterweight and a proximal solid counterweight mounted to the drive shaft along distal end portion of the rotational atherectomy device, the abrasive element being positioned proximal to and spaced away from the distal solid counterweight located at a distal tip of the drive shaft, and the abrasive element being positioned distal to and spaced away from the proximal solid counterweight, each of the distal and proximal solid support elements being substantially smaller than the abrasive element and having a surface texture that is different from an abrasive surface texture of the abrasive element, wherein said distal and proximal solid counterweights are configured to acts as counterweights to the abrasive element when said abrasive element and said distal and proximal solid counterweights rotate together with the drive shaft.   
     
     
         2 . The method of  claim 1 , further comprising contacting the abrasive element of the rotational atherectomy device with the stenotic lesion in the blood vessel during rotation of the drive shaft together with the abrasive element and the distal and proximal solid counterweights. 
     
     
         3 . The method of  claim 2 , further comprising aspirating into a lumen of a drive shaft sheath abraded particles entrained in a retrograde fluid flow after said particles are removed from the stenotic lesion. 
     
     
         4 . The method of  claim 1 , wherein each of the outflow ports is in fluid communication with the fluid delivery lumen of the drive shaft, and said step of outputting fluid flow in a generally radially outward direction through the outflow ports comprises delivering the fluid through the fluid delivery lumen of the drive shaft and to the distal solid counterweight and the proximal solid counterweight. 
     
     
         5 . The method of  claim 1 , wherein each of the distal and proximal solid counterweights has a rounded outer surface that is different from an outer surface of the abrasive element. 
     
     
         6 . The method of  claim 1 , wherein the outflow port of the distal solid counterweight and the outflow port of the proximal solid counterweight have axes that are generally orthogonal to the longitudinal axis of the drive shaft. 
     
     
         7 . The method of  claim 1 , wherein the fluid delivery lumen includes a fluid impermeable membrane that is positioned radially inward of the torque transmitting coil of the drive shaft. 
     
     
         8 . The method of  claim 7 , wherein the fluid impermeable membrane lines the torque transmitting coil. 
     
     
         9 . The method of  claim 1 , wherein the fluid delivery lumen includes a fluid impermeable membrane that is positioned radially outward of the torque transmitting coil of the drive shaft. 
     
     
         10 . The method of  claim 9 , wherein the fluid impermeable membrane lines the torque transmitting coil. 
     
     
         11 . The method of  claim 1 , wherein each of the distal and proximal solid counterweights has multiple outflow ports which are in fluid communication with the fluid delivery lumen of the drive shaft and which extend in radially outward directions with respect to the longitudinal axis of the drive shaft. 
     
     
         12 . The method of  claim 1 , wherein the fluid delivery lumen of the drive shaft is configured for advancement of the drive shaft over a guidewire across the stenotic lesion to be treated and for transfer of pressurized fluid into the outflow ports of the distal solid counterweight and the proximal solid counterweight after crossing the stenotic lesion.