Intraluminal directed ultrasound delivery device

• US 6,024,718 A
• Filed: 09/04/1997
• Issued: 02/15/2000
• Est. Priority Date: 09/04/1996
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Chen, Hank H., Ji, Cheng
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): Hayes, Michael J.
• Application Number:
  US08/923,609
• Time in Patent Office: 894 Days
• Field of Search: 604/22, 604/49, 604/101, 604/128, 604/194, 606/169, 601/2, 600/459
• US Class Current: 604/22
• CPC Class Codes: A61B 17/2202 the ultrasound transducer being inside patient's body at the distal end of the catheter
• CPC Class Codes: A61B 2017/22084 stone- or thrombus-dissolving
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61M 37/0092 using ultrasonic, sonic or infrasonic vibrations, e.g. phonophoresis

Abstract

An ultrasound catheter comprises a coaxial cable of electrical conductors with a piezoelectric element at its distal end. The piezoelectric element is shaped and disposed according to the desired ultrasonic field. When an electrical signal from a signal generator is connected to the electrical conductors, the piezoelectric element mechanically deforms in response and generates ultrasonic energy. An alternative embodiment of the present invention is a hollow tubular catheter of flexible polymer has at its distal end a cylindrical piezoelectric element connected to electrical conductors running the length of the catheter. The piezoelectric cylinder may be tapered, segmented, shortened, etc. according to the desired focusing of the ultrasonic field, which is preferably forwardly focused. In either embodiment the catheter is threaded through a patient'"'"'s vasculature and brought in close proximity to a vascular occlusion. Thrombolytic agents are released from the ultrasonic catheter or a second catheter in close proximity. These agents and ultrasonic energy from the ultrasound catheter result in breakup of the occlusion through sonophoresis.

Claims

1. An improved method for opening occluded vascular elements of the type wherein ultrasound and thrombolytic agents are used to dissolve an occlusion, the improvement comprising the steps of:

inserting an ultrasound catheter having a longitudinal axis including a shaped, distally disposed and forwardly oriented piezoelectric ultrasound generating tip into a patient'"'"'s vascular system so that the tip of said catheter is in proximity to a vascular occlusion;

energizing the shaped piezoelectric ultrasound generating tip to radiate concentrated wavefronts of a forwardly focussed beam of ultrasound energy from said transducer toward said occlusion in the direction of said longitudinal axis; and

releasing thrombolytic agents in proximity of said occlusion so that sonophoresis of said occlusion occurs.

2. A method for removing an occlusion from a patient'"'"'s vascular system comprising the steps of:

inserting an ultrasound catheter into a patient'"'"'s vascular system, the catheter comprising;

an elongate body containing two electrical conductors connected to a signal generator;

a shaped piezoelectric transducer disposed at a distal end of the elongate body in electrical communication with the conductors, said shaped piezoelectric transducer having a shape and orientation on said distal end which longitudinally and forwardly directs a focussed ultrasound beam in concentrated wavefronts toward said occlusion to concentrate ultrasound power of said transducer to increase energy intensity in a defined forward direction; and

radio-opaque material covering at least a portion of the transducer;

monitoring the position of the transducer fluoroscopically and bringing it into the proximity with a vascular occlusion;

infusing thrombolytic agents into contact with the vascular occlusion; and

energizing the piezoelectric transducer to forwardly radiate said focussed ultrasonic beam generated by the transducer into said vascular occlusion in combination with the thrombolytic agents to disperse the occlusion through sonophoresis.

3. An ultrasound catheter for removing vascular occlusions through sonophoresis for use with a signal generator comprising:

an elongate catheter body comprised of two conductors separated by an electrically insulating material and connected to said signal generator;

a shaped piezoelectric ultrasound transducer at a distal end of the catheter body in which a shape is defined for said shaped piezoelectric ultrasound transducer to radiate a a focussed beam of ultrasound energy from said piezoelectric ultrasound transducer in a forwardly concentrated beam in which concentrated wavefronts are directed toward said occlusion to concentrate ultrasound power of said transducer to increase energy intensity in a defined forward direction, a first surface of the shaped piezoelectric ultrasound transducer in electrical contact with a first of the conductors and a second surface in electrical contact with a second of the conductor; and

a radio-opaque material surrounding the shaped piezoelectric ultrasound transducer.

4. An ultrasound catheter for removing a vascular occlusion through sonophoresis used in combination with a signal generator comprising:

an elongate tubular catheter body having a central lumen;

two electrical conductors running the length of the catheter body and connected to said signal generator;

a hollow cylindrical ultrasound transducer having two open ends and an inner and outer surface, said hollow cylindrical ultrasound transducer disposed at a distal end of the catheter body with the central lumen of the catheter body in fluidic communication with one of the open ends of the hollow cylindrical transducer, said inner surface of the transducer in electrical communication with a first of the two electrical conductors and said outer surface of the transducer in electrical communication with a second of the two electrical conductors, wherein the ultrasound transducer is a hollow truncated cone so that a terminal opening of the transducer has a smaller inner diameter than an inner diameter of the catheter body such said hollow truncated cone directs an increased portion of ultrasound energy output by said ultrasound transducer forwardly in the direction of said occlusion as compared to a cylindrical transducer, while still maintaining a high degree of fluidic communication through said hollow cylindrical ultrasound transducer in the direction of said occlusion; and

a radio-opaque material surrounding at least part of the transducer.

5. An ultrasound catheter for removing vascular occlusions through sonophoresis comprising:

an elongate catheter body comprised of two conductors separated by an electrically insulating material;

a piezoelectric ultrasound transducer having a forwardly disposed primary radiating surface at a distal end of the catheter body, positioned on said distal end to radiate a focussed beam of ultrasound energy in concentrated wavefronts toward said occlusion to concentrate ultrasound power of said transducer to increase energy intensity in a defined forward direction, a first surface of the transducer in electrical contact with a first of the conductors and a second surface in electrical contact with a second of the conductor; and

a radio-opaque material surrounding the transducer.

6. The ultrasound catheter of claim 5, wherein the distal end of the catheter is concave in cross-section.

7. The ultrasound catheter of claim 5, wherein the distal end of the catheter is convex in cross-section.

8. An ultrasound catheter for removing vascular occlusions through sonophoresis comprising:

an elongate tubular catheter body having a central lumen;

two electrical conductors running the length of the catheter body;

a hollow cylindrical ultrasound transducer disposed at a distal end of the catheter body with the lumen of the catheter body in fluidic communication with one of the open ends of the cylindrical transducer, one surface of the transducer in electrical communication with a first of the conductors and a second surface of the transducer in electrical communication with a second of the conductors, wherein the ultrasound transducer is a hollow truncated cone so that a terminal opening of the transducer has a smaller inner diameter than an inner diameter of the catheter body; and

a radio-opaque material surrounding at least part of the transducer.