CRYOABLATION
TECHNOLOGY
History of Cryotherapy
First and Second Generation
Cryotherapy History
First Generation Cryosurgical Ablation
Liquid nitrogen cryogen was introduced into clinical practice in 1950 for the cryosurgical ablation of a variety of skin diseases. After the Second World War, liquid nitrogen became freely available. Allington used a cotton swab for treating various benign lesions but the method was insufficient for tumor treatment.
In 1961, the first cryosurgical equipment using liquid nitrogen was developed. Dr. Irving S. Cooper, an American neurosurgeon based in New York. He designed a liquid nitrogen probe with which he treated Parkinson's disease as well as inoperable brain tumors. His work led to increased interest in liquid nitrogen and helped to accelerate its acceptance as a standard for cryotherapy ablation. More general use of cryosurgery was also facilitated by the development of various devices suitable for ablation treatment in the doctor’s office.
While systems that employed liquid nitrogen were fairly simple and inexpensive, cryosurgery was performed by pouring liquid nitrogen via a funnel and did not provide accurate ablation. Large diameter probes subsequently replaced the funnels. Many new applications for cryosurgery were introduced during this time, including uterine, prostate, orthopedics, skin and sports injuries applications. Due to difficulties in controlling the size of the iceball and its freezing-thawing characteristics, these cryo treatments resulted in significant complications.
Second Generation Cryosurgery
Cryosurgery experienced a revival in the mid eighties with imaging-monitored cryosurgery and the first clinical reports of liver and prostate cancer treatments were published.
In the late 1980’s and throughout the 1990’s, second generation cryosurgery systems emerged, based on an advanced gas expansion method (Joule-Thomson principle). Although these systems demonstrated significant improvement in controlling the freezing process, they employed large diameter (3.2 mm) probes.
Joule-Thomson cycle cryoprobes had several
advantages over systems that utilized liquid nitrogen.
The refrigerant could be stored room temperature
and the difficulties associated with supplying
liquid nitrogen to the operating room disappeared.
However, in order to avoid damage to adjacent
healthy tissue, the probes were operated at only
25-50% of their maximum freezing power. The deliberately
smaller iceballs generated by a few probes resulted
in non-uniform isotherms.
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