
Radio Frequency Ablation-- How Does it Work?
Radiofrequency is a type of
electrical energy that has been used in medical procedures for decades.
At the most basic level, this electrical energy is used to create heat.
The heat is created in a specific location, at a specific temperature,
for a specific period of time, and ultimately results in the death of
unwanted tissue.
During a radiofrequency procedure,
an ablation probe is placed directly into the target tissue. An array
of several small, curved electrodes are deployed from the end of the probe
into the tissue. The generator is turned on and target temperatures are
input. The radiofrequency energy flows through the electrodes, causing
ionic agitation, and therefore friction, in the nearby tissue. This friction
creates heat, and once sufficient temperatures have been reached, the
heat kills the target tissue within a few minutes. Thermocouples (tiny
thermometers) incorporated into the tips of the electrodes allow continuous
monitoring of tissue temperatures, and power is automatically adjusted
so that the target temperatures remain constant. Ultrasound is typically
used to monitor the treatment process.
Heat is a very effective means
of killing tissue. As tissue temperature rises above 113° F (50° C), protein
is permanently damaged and cell membranes fuse. The process is rapid,
typically requiring less than 10-15 minutes exposure time for a 3 cm ablation.
Depending on the power applied
and the resistance of the tissues, heat decreases rapidly at a specific
distance from the electrode tip, limiting the ablation size. The size
of the ablated area is determined largely by the size of the probe, the
temperature of the tissue, and the duration of time the energy is applied.
There is a sharp boundary between dead tissue and unaffected surrounding
tissue. Thus unwanted tissue can be ablated without much sacrifice of
surrounding normal tissue.
What is an RF Procedure Like?
Your physician can tell you
what to expect before and after the procedure. There are several different
ways that a RF procedure may be performed, and each has different benefits,
limitations, and applicability. Your physician can determine which is
most suitable for you.
One option is a percutaneous
approach, in which the electrode is inserted through the skin to the desired
location. The physician usually uses ultrasound to guide the needle to
the right location. This is the least invasive way that RF is performed.
General anesthesia is usually not necessary, but typically the patient
is sedated. Often the patient is able to go home the same day.
If general anesthesia is not used, some discomfort or pain may be felt
while the area is being ablated.
Options
Another option is a laparoscopic
approach. With this approach, the surgeon makes a few small incisions
in the abdomen, through which the necessary instruments are passed in
order to treat the target tissue. This is also a minimally invasive approach,
although general anesthesia is necessary. Patients typically go home the
next day. One advantage of this approach is that intraoperative ultrasound
can be used, which may result in more accurate location and visualization
of the target tissue.
A third option is the open
approach. This is what most people probably think of when they think of
an operation. An incision is made in the area to be treated, and the surgeon
can directly visualize the procedure. General anesthesia is necessary,
and the recovery period is a bit longer.
Patients may experience a slight fever for two or three days after the
procedure. Physicians often allow the fever to resolve without intervention.
RF ablation procedures have a relatively low rate of complications (~
3.6%). Most of the complications are considered minor. The following are
the complications associated with this procedure: infection (abscess),
bleeding, collapse of the lung, abnormal heart rhythms, and skin burn.