The History of Ultra-low Temperature Cryoablation

The history of cryotherapy can be traced back to 3500 years ago, when scholars applied freezing methods to treat skin diseases. However, the establishment of modern cryomedicine is of recent years. Therefore, ultra-low temperature cryoablation is an old and young medical technology.

In the late 19th century, several important discoveries in the field of cryogenics, including systems for adiabatic expansion of pure oxygen, air, and nitrogen liquefaction, vacuum flasks capable of storing and handling liquefied gases, and the application of the Joule-Thomson effect to produce a continuous stream of liquefied gases, contributed to the development of cryotherapy.

The liquefaction of hydrogen, helium, and nitrogen was successful in the early 1940s, and liquid nitrogen was first used in the clinic in 1950, when it was applied directly to lesions for the treatment of a variety of skin diseases.

Before the 1960s, the therapeutic depth of the equipment used for cryotherapy was only a few millimeters, so it was mainly applied to the treatment of skin and gynecological areas of some superficial lesions, and clinicians also did a lot of research on freezing, but it was mainly a study of the functional changes in frozen tissues rather than a study of therapeutic applications.

In the 1960s, cryogenic instruments and equipment were improved and developed. A cryotherapy probe was successfully prepared for controlled freezing of deep tissues in the body, and has been used to treat a variety of diseases, including anorectal diseases, uterine disorders, neurological disorders, prostate disorders, osteoarthritic disorders, and skin disorders.

By the 1980s, cryotherapy had gained further attention, largely due to the improvement and development of cryosurgical instruments and equipment. During this period, a catheter capable of circulating a cryogenic source was successfully prepared; alcohol mixtures and Freon were used as cryogens in clinical treatments. The development of cryotherapy was strongly promoted. They prepared a cryotherapy probe with which lesions in brain tissue could be accurately frozen. This probe was in fact the prototype for the various liquid nitrogen cryoprobes that followed. The probe consists of three long concentric tubes, the inner tube as a conduit, so that the liquid nitrogen in a compressed state flow to the tip of the probe; the inner tube and the gap between the middle tube, used as a gaseous nitrogen from the top of the probe back to the pathway; the gap between the outer tube and the middle tube for the vacuum insulation to ensure that liquid nitrogen flow to the top of the probe will not be subjected to thermal vaporization; the tip of the probe has a "chamber ", liquid nitrogen from the inner tube flow to the "room" in this gasification, a large number of surrounding tissue heat absorption, so that the surrounding tissue can be frozen. With this cryoprobe, controlled freezing of deep tissues in the body is possible.

The establishment of truly "modern" cryotherapy began in the late 1990s, thanks to advances in both imaging technology and new freezing equipment. Thanks to the widespread use of ultrasound and CT, under the monitoring and guidance of imaging technology, cold probes can be inserted accurately, the process of freezing can be observed in real time, and the extent of freezing can be finely controlled, thus ensuring that the target tissues can be effectively frozen without damaging or minimizing the damage to normal tissues. The introduction and application of rectal ultrasound and surgical ultrasound probes have strongly promoted the application of freezing in the treatment of anorectal diseases and rectal tumors. In recent years magnetic **** vibration (MRI) is applied to the monitoring of cryotherapy, so that cryotherapy shows more minimally invasive and targeted advantages.

In the 1990s, with the development of imaging technology as well as new freezing equipment, modern cryotherapy was gradually established. Liquid nitrogen freezing system and argon helium freezing system represent two important development stages of cryotherapy. The application of argon-helium cryotherapy system has raised the minimally invasive treatment of anorectal diseases and rectal tumors to a new level.

At present, cryotherapy has been widely applied to anorectal diseases, cervical erosion, and rectal tumors, and can be performed during surgery, endoscopically, or by percutaneous route. Cryotherapy has been extended from former anorectal diseases, cervical celiac disease, rectal tumors to prostate cancer, liver, lung, kidney, breast, uterus, ovary, bone, skin and various soft tissue benign and malignant tumors.