Atherectomy device

A laterally self-directed atherectomy device for locating and piercing a relatively soft plaque region of a chronic total occlusion within a blood vessel which is characterized by complete interruption of blood flow and formation of hardened atherosclerotic plaque, and for enlarging a pierced opening within the chronic total occlusion, said atherectomy device comprising a distal portion which is unrestrained by a guidewire when the relatively soft plaque region is pierced, wherein said distal portion comprises:

• a) a rotatably motor-driven flexible hollow shaft;
• b) an annular extreme distal tip of the hollow shaft configured with circumferentially extending and distally facing cutting surfaces for piercing a relatively soft plaque region of a chronic total occlusion that has accumulated within a blood vessel;
• and
• c) an asymmetric and radially rigid helical strand drilling unit connected to the hollow shaft for enlarging a pierced opening formed by the cutting surfaces of the extreme distal tip, the helical strand drilling unit configured with a drilling inducing trapezoidal cross section having a laterally outwardly disposed side, a laterally inwardly disposed side defining a diameter larger than the cutting surfaces of the extreme distal tip and which is significantly shorter than said laterally outwardly disposed side, and two opposite intermediate sides each extending between a corresponding end of said laterally inwardly disposed side and said laterally outwardly disposed side,
• wherein the helical strand drilling unit is wound about the hollow shaft in such a way that only one diametrical end of the hollow shaft is surrounded by the helical strand drilling unit for a given longitudinal length of the hollow shaft, and has a radial separation from the hollow shaft at one longitudinally central region of the helical strand drilling unit that is significantly greater than the radial separation from the hollow shaft at other longitudinal regions of the helical strand drilling unit, to facilitate eccentric rotation of the hollow shaft about a longitudinal axis of the atherectomy device for cutting and removing occlusive material from the blood vessel,
• wherein all peripheral and diametrically outwardly disposed surfaces of said distal portion are curved to ensure atraumatic contact with a wall of the blood vessel during lateral movement of the atherectomy device,
• wherein the hollow shaft, in cooperation with the significant radially separated configuration at said one central region of said helical strand drilling unit and with operation of a motor, is eccentrically rotatable about the longitudinal axis to result in lateral displacement in a first direction within the blood vessel and subsequently in a second direction opposite to said first direction in response to atraumatic impact between the helical strand drilling unit and a wall of the blood vessel,
• wherein the cutting surfaces of the extreme distal tip, during distal displacement of the atherectomy device and following the lateral displacement, are deflected upon contact with a hardened plaque region of the chronic total occlusion and are configured, upon contact with the relatively soft plaque region of the chronic total occlusion, to pierce the relatively soft plaque region, and leading intermediate side surfaces of the helical strand drilling unit with respect to a rotational direction of the hollow shaft are configured to sequentially enlarge the pierced opening during a drilling operation while said extreme distal tip remains in engagement with the relatively soft plaque region.

A self-centering atherectomy device configured with a distal portion having a gradually increasing diameter in the proximal direction for opening a chronic total occlusion within a blood vessel being characterized by complete interruption of blood flow, said distal portion comprising:

• a) a rotatably motor-driven flexible hollow shaft that is slidable over, and is coaxial with, a longitudinal axis of a guidewire;
• b) an annular extreme distal tip of the hollow shaft having a first diameter that is only slightly larger than the diameter of the guidewire and configured with circumferentially extending and distally facing cutting surfaces defining said first diameter for piercing hardened atherosclerotic plaque of a chronic total occlusion that has accumulated within a blood vessel;
• c) a tubular sleeve proximally spaced from said extreme distal tip of the hollow shaft, and fitted over, and secured to, a first peripheral surface of the hollow shaft, wherein a distal end of said sleeve has a slightly larger second diameter than said extreme distal tip of the hollow shaft and is configured with cutting surfaces for enlarging an opening formed in the plaque;
• and
• d) an asymmetric cutting unit extending between said sleeve and a second peripheral surface of the hollow shaft which is proximally spaced from said first peripheral surface, said cutting unit defining a diameter larger than said sleeve for additionally enlarging said opening and having a radial separation from said hollow shaft at one longitudinally central region of said cutting unit that is significantly greater than the radial separation from said hollow shaft at other longitudinal regions of said cutting unit,
• wherein said cutting unit is inexpandable and is integral with the hollow shaft,
• wherein all peripheral and diametrically outwardly disposed surfaces of said distal portion are curved to ensure atraumatic contact with a wall of the blood vessel during lateral movement of the atherectomy device,
• wherein the hollow shaft, in cooperation with the significant radially separated configuration at said one central region of said cutting unit and with operation of a motor, is eccentrically rotatable about the longitudinal axis to result in lateral displacement in a first direction within the blood vessel and subsequently in a second direction opposite to said first direction in response to atraumatic impact between said cutting unit and a wall of the blood vessel, so as to be substantially self-centered within the blood vessel as a result of alternating lateral movement,
• wherein the cutting surfaces of said extreme distal tip, during distal displacement of the atherectomy device and following a self-centering action, are configured to pierce a central relatively soft plaque region of the chronic total occlusion, and the cutting surfaces of said sleeve and of said cutting unit are configured to sequentially enlarge the opening while said extreme distal tip remains in engagement with said central region.