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| Screw for lumbar-sacral fixator |
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| Spinal osteosynthesis device |
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| Medical electrode and method |
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| Iontophoretic electrode |
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| Bone assessment apparatus and method |
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Ultrasonic freeze ablation catheters and probes
| Details |
Inventors: Hed, Aharon Z.;
Assignee:
Primary Examiner: Aschenbrenner; Peter A.
Assistant Examiner:
Attorney, Agent or Firm: Gerber; Eliot S.
Probes for medical surgery and flexible catheters for internal tissue ablation in which the tissue cells are frozen and deadened and yet extreme supercooling of tissue below the tissues' melting point is not required. The tissue cells are moderately supercooled by the probe or catheter and freezing of the cells is caused by cavitation nucleation of ice particles within the cells induced by a low power ultrasonic wave generator. The ultrasonic energy causes well distributed nucleation in the supercooled tissue cells and, as a result, the cells rapidly freeze and, due to such freezing, expand and burst their membranes. |
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DETAILED DESCRIPTION In accordance with the present invention, there is provided a probe or catheter used to deaden tissue cells at a small selected location, for example, to destroy arrhytmogenic foci in cardiac procedures.
The probe has a head portion and an elongated tubular portion leading to the head portion.
The tubular portion is a conduit, in one embodiment, from a source of cooled liquid to the head portion and a return from the head portion.
Preferably the tubular portion is a coaxial member having an inner bore through an inner tube (inner lumen), an outer tube (outer lumen), and a liquid flow path between the inner and outer tubes.
The flow of cooled liquid to the head portion rapidly cools the tissue cells proximate the head portion to below freezing, in the range of about -10.
degree.
C.
to -50.
degree.
C.
, without cooling the cells below about -50.
degree.
C.
While the tissue cells are supercooled, they are subjected to ultrasonic cavitation energy which is within a critical range of power so as to cause nucleation of ice within the cells.
Preferably the ultrasonic energy is from a transducer at the probe head portion; however, in appropriate situations the ultrasonic energy may be applied non-invasively by a transducer applied to the skin of the patient.
The probe is less likely to cause damage to cells beyond those sought to be killed due to the limited temperature and rate of its supercooling, i.
e.
, above -50.
degree.
C.
and due to the low power of its ultrasonic energy, which is considerably below the ultrasonic power required to rupture cells.
OBJECTIVES OF THE INVENTION It is a primary object of the instant invention to provide improved medical surgical methods and devices which avoid the need for a cryogenic probe using high gas pressure.
It is another object of the present invention to provide for intra-cellular nucleation in the target tissues at temperatures which are close to the melting temperature of physiological tissues and thus avoid the need for very rapid supercooling of the tissues
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Obesity Surgery 
