Method for removing plaque from blood vessels using ultrasonic energy

Abstract

A method and apparatus for removing plaque, fatty deposits, and other occlusions from blood vessels using ultrasonic energy. The method and apparatus has particular application in removing plaque from the carotid artery in a non-thermal manner. The apparatus is designed to have as small a cross-sectional profile as possible, therefore allowing the apparatus to be used in a minimally-invasive manner. As a result, the apparatus can be used in both surgical and outpatient treatment with minimal post-operative complications and minimal damage to areas other than the area of treatment. An ultrasonic probe may include aspiration channels on its outer surface. An aspiration sheath may surround the ultrasonic probe, such that the location of an aspiration port may be varied axially relative to the ultrasonic tip.

1 . A method for removing plaque from a blood vessel using an ultrasonic energy, comprising the steps of: 
 inserting an ultrasonic probe into the blood vessel;    extending a portion of the ultrasonic probe to an area adjacent to the plaque on an inner surface of the blood vessel;    transmitting ultrasonic vibrations to the portion of the ultrasonic probe;    reducing the plaque to a particulate material by producing cavitation in a vicinity of the plaque.    
     
     
         2 . A method of  claim 1  wherein the ultrasonic vibrations are transmitted in an axial direction along the ultrasonic probe and in a direction transverse to an axial direction of the ultrasonic probe.  
     
     
         3 . The method of  claim 1  further comprising irrigating the plaque with a fluid before transmitting the ultrasonic vibrations to the portion of the ultrasonic probe.  
     
     
         4 . The method of  claim 1  further comprising aspirating the particulate material after reducing the plaque to the particulate material.  
     
     
         5 . The method of  claim 1  wherein the blood vessel is a carotid artery.  
     
     
         6 . The method of  claim 1  wherein the transmitting of the ultrasonic vibrations is at a power level sufficient to reduce the plaque to the particulate material having individual particles with a diameter at least as small as about 10 microns.  
     
     
         7 . The method of  claim 1  further comprising monitoring a location of the distal end of the ultrasonic probe in the blood vessel.  
     
     
         8 . The method of  claim 7  wherein the location of the distal end of the ultrasonic probe is monitored using ultrasound.  
     
     
         9 . A method for reducing plaque in a blood vessel comprising: 
 providing a flexible member comprising a proximal end, a distal end and a longitudinal axis between the proximal end and the distal end;    inserting the flexible member into the blood vessel;    moving the flexible member in the blood vessel and placing the flexible member in communication with the plaque; and    providing an ultrasonic vibration to the flexible member, creating a transverse ultrasonic vibration along at least a portion of the longitudinal axis of the flexible member with a plurality of anti-nodes along the flexible member.    
     
     
         10 . The method of  claim 9  wherein the flexible member is an ultrasonic probe.  
     
     
         11 . The method of  claim 9  further comprising reducing the plaque to a particulate material having a diameter less than about 10 microns.  
     
     
         12 . The method of  claim 9  wherein the plurality of anti-nodes create a cavitation in a fluid surrounding the flexible member to ablate the plaque.  
     
     
         13 . The method of  claim 9  wherein an ultrasonic vibration generator produces the ultrasonic vibration in a range of about 20 kHz to about 80 kHz.  
     
     
         14 . The method of  claim 9  further comprising moving the flexible member in an axial direction within an aspiration sheath to move the distal end of the flexible member axially inwardly and axially outwardly relative to a distal end of the aspiration sheath.  
     
     
         15 . The method of  claim 9  wherein the flexible member comprises a flexibility to support the transverse ultrasonic vibration.  
     
     
         16 . A method for removing a fatty deposit from a carotid artery comprising: 
 providing an ultrasonic probe comprising a proximal end, a distal end and a longitudinal axis between the proximal end and the distal end;    inserting the ultrasonic probe into the carotid artery;    moving the ultrasonic probe in the carotid artery and placing the ultrasonic probe in communication with the fatty deposit;    providing an ultrasonic vibration to the ultrasonic probe, creating a transverse ultrasonic vibration along at least a portion of the longitudinal axis of the ultrasonic probe with a plurality of anti-nodes along the ultrasonic probe; and    reducing the fatty deposit to a particulate material by producing an area of non-thermal cavitation in a vicinity of the fatty deposit.    
     
     
         17 . The method of  claim 16  wherein the fatty deposit is reduced to a diameter less than or equal to about 10 microns.  
     
     
         18 . The method of  claim 16  wherein an ultrasonic vibration generator produces the ultrasonic vibration in a range of about 20 kHz to about 80 kHz.  
     
     
         19 . The method of  claim 16  further comprising irrigating the fatty deposit with a fluid before providing the ultrasonic vibration to the ultrasonic probe.  
     
     
         20 . The method of  claim 16  further comprising aspirating the particulate material after reducing the fatty deposit to the particulate material.