Transducer assembly and method for coupling ultrasonic energy to a body for thrombolysis of vascular thrombi

• US 5,879,314 A
• Filed: 09/02/1997
• Issued: 03/09/1999
• Est. Priority Date: 06/30/1997
• Status: Expired due to Fees

• Current Assignee: Cybersonics, Inc
• Original Assignee: Cybersonics, Inc
• Inventors: DeCastro, Eugene, Peterson, Thomas M., Dharmendra, Pal
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US08/922,188
• Time in Patent Office: 553 Days
• Field of Search: 601/2-4, 600/439, 604/22
• US Class Current: 601/2
• CPC Class Codes: A61B 17/2251 characterised by coupling elements between the apparatus, e.g. shock wave apparatus or locating means, and the patient, e.g. details of bags, pressure control of bag on patient
• CPC Class Codes: A61B 2017/22084 stone- or thrombus-dissolving
• CPC Class Codes: G10K 11/02 Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Abstract

A transducer assembly and method for coupling ultrasonic energy to a body for thrombolysis of vascular thrombi is provided. The assembly includes a catalytic transducer for transmitting ultrasound into a medical target transcutaneously. The catalytic transducer includes a front mass having structure which optimizes the transmission of ultrasound into the body. A reservoir for containing a cooling conductive medium between the front mass and the body surface is provided, and is contained within the housing. In addition, the catalytic transducer includes an irrigation manifold, disposed through a center of the front mass, for directing the media into the reservoir generally along a perimeter thereof. The front mass includes an apex for accumulating expelled gasses. A sloped surface of the front mass functions to direct expelled gasses toward the apex and through an outlet provided by the irrigation manifold. The medium may be circulated from a degassing tank as well as a heat exchange unit in order to maintain a desired reservoir temperature at the body surface.

Claims

1. Ultrasonic medical apparatus comprising:

a housing;

means, including a piezoelectric element, enclosed in said housing for generating ultrasonic waves;

a front mass disposed in said housing;

means for radiating the ultrasonic waves into a medical target in a patient;

reservoir means including a flexible membrane for containing a fluid conductive medium between the front mass and the flexible membrane to thereby provide an interface between said fluid conductive medium and a body surface of a patient and for coupling the radiated ultrasonic waves into the body surface;

a fluid conductive medium contained in said reservoir means; and

flow management means, defining an arcuate surface area on said front mass, for accumulating and removing expelled gasses from the reservoir means in order to enhance the transmission of the ultrasonic waves into the medical target, said arcuate surface area comprising concavity means, including an concavity apex, for enabling gasses expelled from the fluid conductive medium to accumulate at the concavity apex, and outlet means, in fluid communication with said reservoir means and disposed generally at said concavity apex, for passing fluid conductive medium and accumulated gasses out of the reservoir means.

2. The ultrasonic medical apparatus according to claim 1 wherein the flow management means further includes inlet means for directing fluid conductive medium into the reservoir means adjacent a perimeter of the front mass surface area.

3. The ultrasonic medical apparatus according to claim 1 wherein the flow management means includes an irrigation manifold disposed through the front mass, said irrigation manifold including both inlet means for directing fluid conductive medium into the reservoir means adjacent a perimeter of the front mass surface area, and outlet means for passing expelled gasses out of the reservoir means through generally the concavity apex.

4. The ultrasonic medical apparatus according to claim 1 further comprising a cooling source and cooling means for maintaining a desired temperature at the body surface of the patient, said cooling means including means for circulating the fluid conductive medium between the reservoir means and the cooling source.

5. The ultrasonic apparatus according to claim 4 further comprising flexible arm means, connected to a back end of the housing, for positioning the ultrasonic medical apparatus on the body surface of the patient, and wherein said means for circulating is disposed through the flexible arm means.

6. Ultrasonic medical apparatus comprising:

a housing;

means, including a piezoelectric element, enclosed in said housing for generating ultrasonic waves;

front mass means, disposed in said housing, for radiating the ultrasonic waves into a medical target in a patient;

a fluid conductive medium;

reservoir means including a flexible membrane containing the fluid conductive medium between the front mass means, the flexible membrane providing an interface between said fluid conductive medium and the body surface of the patient,

flow management means, defined by an outlet through the front mass means, for removing expelled gasses from the reservoir means in order to enhance the transmission of the ultrasonic waves into the medical target, said front mass means including a sloped surface comprising concavity means, including a concavity apex, for enabling gasses expelled from the fluid conductive medium to accumulate at the concavity apex, and outlet means, in fluid communication with said reservoir means and disposed generally at said concavity apex, for passing fluid conductive medium and accumulated gasses out of the reservoir.

7. The ultrasonic medical apparatus according to claim 6 wherein the flow management means further comprises inlet means for directing the fluid conductive medium into the reservoir means along a boundary thereof.

8. The ultrasonic medical apparatus according to claim 6 further comprising a cooling source and cooling means for maintaining a desired temperature at the body surface of the patient, said cooling means including means for circulating the fluid conductive medium between the reservoir means and the cooling source.

9. A method for coupling ultrasonic energy to a body for dissolution or treatment of a medical target the method comprising the steps of:

positioning an ultrasonic transducer having a radiator comprising a front mass having an arcuate or sloped surface onto a body surface over the medical target;

radiating ultrasound waves from the ultrasonic transducer into the medical target beneath the body surface to thereby dissolve or treat the medical target;

containing a fluid conductive medium in the transducer by confining the fluid conductive medium in a reservoir between the arcuate or sloped surface of the radiator and the body surface;

circulating the fluid conductive medium between a replenishing source of fluid conductive medium and the transducer;

accumulating, in the transducer reservoir, gasses expelled from the circulating fluid conductive medium; and

removing the accumulating gasses from the transducer reservoir through outlet means disposed generally at the apex of said sloped or arcuate surface of the radiator.

10. The method according to claim 9 further comprising the step of disposing a medicinal agent adjacent the medical target prior to the step of radiating ultrasound waves.

11. The method according to claim 9 further comprising the step of cooling the fluid conductive medium during the step of circulating the fluid conductive medium.

12. The method according to claim 9 wherein the step of circulating comprises the steps directing fluid conductive medium into the transducer reservoir along a perimeter of the reservoir and passing the directed fluid conductive medium and accumulated gasses from the reservoir through generally a center of the reservoir and returning said directed fluid to the replenishing source.