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Radiofrequency thermocoagulation

About radiofrequency ablation

Radiofrequency generators have been used in medicine for around a century, and RF is widely used in a multitude of disciplines; in fact, an estimated four out of every five surgical procedures now employ radiofrequency energy in some form. Some of its most promising newer applications are based on the principle of thermocoagulation, in which heat is used to destroy tissue—but as with many things, that description only scratches the surface of what is really going on. 

For example, the phrase “heat is used to destroy tissue” could apply to electrocautery as well, but the two procedures differ in several key respects. In electrocautery, the generated energy is used to heat a metal wire, which the practitioner then applies directly to the tissue, causing damage similar to third-degree burns. In radiofrequency ablation, on the other hand, the electrode remains cool, because the heat used for thermocoagulation is generated in the tissue itself.

How? Monopolar RF generators create a closed electrical loop: from the generator to the patient’s body, to the electrosurgical pad (if used), to the generator. This electrical current is painless for the patient because the frequency is too high to trigger depolarisation of nerve membranes, so the nerves never fire. The high-frequency current agitates the ions within the tissue as they attempt to follow the alternating current’s changes in direction—which happen so fast that the ions vibrate without moving. Such vibration creates significant frictional heat in the immediate vicinity of the electrode, but the effect decreases dramatically with distance: a 2 mm Rafaelo® electrode, for example, has a thermal radius of just 3 mm. This represents a major advantage over electrocautery, which typically has a significantly greater range of heat spread (and thus greater potential for inadvertent tissue damage).

Key advantages of radiofrequency ablation

  • Minimally invasive: no incision required, which reduces the risk of complications
  • Small thermal radius: mechanism of heat generation prevents damage to surrounding tissue
  • Easy to control: 4MHz current has a predictable thermal effect
  • Quick: procedures temperatures capable of causing rapid cellular death, so many procedures take just minutes
  • Versatile: applications in proctology, dermatology, phlebology, and numerous other fields

The actual process of RF thermocoagulation can be broken down into four main elements:

Step 1
Ionic agitation

The alterning current causes the ions within the tissue to vibrate rapidly.

Step 2

The frictional heat generated through ionic agitation causes the cells to dry out and shrink.

Step 3
Denaturation of proteins

The heat breaks down the proteins in the tissue, causing them to unfold.

Step 4
Coagulation by thermal destruction

The proteins coagulate, forming derivatives of collagen that create a “glue” effect.

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