Radio frequency ablation (RFA) is a medical procedure where part of the
electrical conduction system of the heartThe normal intrinsic electrical conduction of the heart allows electrical propagation to be transmitted from the Sinoatrial Node through both atria and forward to the Atrioventricular Node. Normal/baseline physiology allows further propagation from the AV node to the ventricle or Purkinje Fibers...
,
tumorA tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
or other dysfunctional
tissueTissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
is ablated using the heat generated from the high frequency alternating current to treat a medical disorder. An important advantage of RF current (over previously used low frequency AC or pulses of DC) is that it does not directly stimulate nerves or heart muscle and can therefore often be used without the need for general anesthetic. RFA has become increasingly accepted in the last 15 years with promising results. RFA procedures are performed under image guidance (such as
X-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
screening, CT scan or
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
) by an interventional pain specialist (such as an anesthesiologist),
interventional radiologistInterventional radiology is a specialty of radiology, in which image-guided procedures are used to diagnose and treat a multitude of diseases across all body systems...
or a
cardiac electrophysiologistCardiac electrophysiology is the science of elucidating, diagnosing, and treating the electrical activities of the heart. The term is usually used to describe studies of such phenomena by invasive catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical...
, a subspecialty of
cardiologistsCardiology is a medical specialty dealing with disorders of the heart . The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology...
.
Radio frequency ablation (RFA) is a medical procedure where part of the
electrical conduction system of the heartThe normal intrinsic electrical conduction of the heart allows electrical propagation to be transmitted from the Sinoatrial Node through both atria and forward to the Atrioventricular Node. Normal/baseline physiology allows further propagation from the AV node to the ventricle or Purkinje Fibers...
,
tumorA tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
or other dysfunctional
tissueTissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
is ablated using the heat generated from the high frequency alternating current to treat a medical disorder. An important advantage of RF current (over previously used low frequency AC or pulses of DC) is that it does not directly stimulate nerves or heart muscle and can therefore often be used without the need for general anesthetic. RFA has become increasingly accepted in the last 15 years with promising results. RFA procedures are performed under image guidance (such as
X-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
screening, CT scan or
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
) by an interventional pain specialist (such as an anesthesiologist),
interventional radiologistInterventional radiology is a specialty of radiology, in which image-guided procedures are used to diagnose and treat a multitude of diseases across all body systems...
or a
cardiac electrophysiologistCardiac electrophysiology is the science of elucidating, diagnosing, and treating the electrical activities of the heart. The term is usually used to describe studies of such phenomena by invasive catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical...
, a subspecialty of
cardiologistsCardiology is a medical specialty dealing with disorders of the heart . The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology...
.
Radio Frequency Ablation of lung, kidney, breast, bone and liver tumors
RFA is performed to treat tumors in lung, liver, kidney, bone and (rarely) in other body organs. Once the diagnosis of tumor is confirmed, a needle-like RFA probe is placed inside the tumor. The radiofrequency waves passing through the probe increase the temperature within tumor tissue that results in destruction of the tumor. Generally RFA is used to treat patients with small tumors that started within the organ (primary tumors) or that spread to the organ (
metastasisMetastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
). The suitability of a patient to receive RFA is decided by doctors based on multiple factors.
RFA can usually be administered as an out-patient procedure, that may at times require a brief hospital stay. RFA may be combined with locally-delivered chemotherapy to treat hepatocellular carcinoma (primary liver cancer). The low-level heat (hyperthermia) created by the RFA probe causes heat-sensitive liposomes to release concentrated levels of chemotherapy in the margins around the ablated tissue, which is a method commonly used to treat
Hepatocellular carcinomaHepatocellular carcinoma is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitide infection or cirrhosis .Compared to other cancers, HCC is quite a rare tumor in the United States...
(HCC).
Radiofrequency ablation is also used in Pancreatic cancer and bile duct cancer
Use in cardiology
Radiofrequency energy is used to destroy abnormal electrical pathways in heart tissue or normal parts that are contributing to a cardiac arrhythmia. It is used in recurrent
atrial flutterAtrial flutter is an abnormal heart rhythm that occurs in the atria of the heart. When it first occurs, it is usually associated with a fast heart rate or tachycardia , and falls into the category of supra-ventricular tachycardias. While this rhythm occurs most often in individuals with...
,
atrial fibrillationAtrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
(AF),
supraventricular tachycardiaSupraventricular tachycardia is a general term that refers to any rapid heart rhythm originating above the ventricular tissue. Supraventricular tachycardias can be contrasted to the potentially more dangerous ventricular tachycardias - rapid rhythms that originate within the ventricular...
(SVT),
atrial tachycardiaAtrial tachycardia is a type of atrial arrhythmia in which the heart's electrical impulse comes from an ectopic atrial pacemaker rather than from the SA node. Atrial tachycardias are characterized by very regular rates ranging from 140–220 bpm....
and some types of ventricular arrhythmia. The energy emitting probe (electrode) is at the tip of a catheter which is placed into the heart, usually through a vein. THis catheter is called the
ablator. The practitioner first "maps" an area of the heart to locate the abnormal electrical activity (
electrophysiology studyAn electrophysiology study is a minimally invasive procedure which tests the electrical conduction system of the heart to assess the electrical activity and conduction pathways of the heart. The study is indicated to investigate the cause, location of origin, and best treatment for various...
) before the responsible tissue is eliminated. Ablation is now the standard treatment for SVT and typical atrial flutter and the technique can also be used in AF, either to block the
atrioventricular nodeThe atrioventricular node is a part of the electrical control system of the heart that coordinates heart rate. It electrically connects atrial and ventricular chambers...
after implantation of a pacemaker or to block conduction within the
left atriumThe left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
, especially around the pulmonary veins. In some conditions, especially forms of intra-nodal re-entry (the most common type of SVT), also called atrioventricular nodal reentrant tachycardia or AVNRT, RF ablation can also be accomplished by
cryoablationCryoablation is a process that uses extreme cold to remove tissue .Cryoablation is used in a variety of clinical applications using hollow needles through which cooled, thermally conductive, fluids are circulated...
(tissue freezing using a coolant which flows through the catheter) which avoids the risk of complete heart block - a potential complication of RF ablation in this condition. Recurrence rates with cryoablation are higher, though . Microwave ablation, where tissue is ablated by the microwave energy "cooking" the adjacent tissue, and ultrasonic ablation, creating a heating effect by mechanical vibration, or laser ablation have also been developed but are not in widespread use.
In 2004, former British prime minister
Tony BlairAnthony Charles Lynton Blair is a former British Labour Party politician who served as the Prime Minister of the United Kingdom from 2 May 1997 to 27 June 2007. He was the Member of Parliament for Sedgefield from 1983 to 2007 and Leader of the Labour Party from 1994 to 2007...
underwent RF catheter ablation for recurrent atrial flutter.
In AF, the abnormal electrophysiology can also be corrected surgically. This procedure referred to as the "
Cox maze procedureThe Cox maze procedure is a type of heart surgery for atrial fibrillation."Maze" refers to the series of incisions arranged in a maze-like pattern in the atria...
", is mostly performed concomitantly with cardiac surgery.
Treatment of Varicose Veins
Radiofrequency ablation is a minimally invasive procedure used in the treatment of varicose veins. It is an alternative to the traditional stripping operation. Under ultrasound guidance, a radiofrequency catheter is inserted into the abnormal vein and the vessel treated with radio-energy, resulting in closure of the involved vein. Radiofrequency ablation is used to treat the
great saphenous veinThe great saphenous vein , also long saphenous vein, is the large superficial vein of the leg and thigh.The terms "safaina" and "el safin" have both been claimed as the origin for the word "saphenous."-Path:The GSV originates from where the dorsal vein of the first digit...
, the
small saphenous veinThe small saphenous vein , is a relatively large vein of the superficial posterior leg.-Path:Its origin is where the dorsal vein from the fifth digit merges with the dorsal venous arch of the foot, which attaches to the great saphenous vein...
, and the perforator veins. The latter are connecting veins that transport blood from the superficial veins to the deep veins. Branch varicose veins are then usually treated with other minimally invasive procedures, such as
ambulatory phlebectomyAmbulatory phlebectomy is a treatment for superficial varicose veins. The procedure involves the removal of the varicose veins through small 2–3 mm incisions in the skin overlying the veins. The procedure may be performed in hospital or outpatient settings...
,
sclerotherapySclerotherapy is a procedure used to treat blood vessels or blood vessel malformations and also those of the lymphatic system. A medicine is injected into the vessels, which makes them shrink. It is used for children and young adults with vascular or lymphatic malformations...
, or foam sclerotherapy. Currently, the VNUS ClosureRFS stylet is the only endovenous ablation device specifically cleared by FDA for the
treatment of incompetent refluxing perforating veins.
It should be pointed that the possibility of skin burn during the procedure is very small, because thr large volumes (500 cc) of dilute Lidocaine (0.1%) tumescent anesthesia injected along the entire vein prior to the application of radiofrequency provides a heat sink that absorbs the heat created by the device. Early studies have shown a high success rate with low rates of complications.
Pain Management
RFA, or
rhizotomyA rhizotomy is a term chiefly referring to a neurosurgical procedure that selectively severs problematic nerve roots in the spinal cord, most often to relieve the symptoms of neuromuscular conditions such as spastic diplegia and other forms of spastic cerebral palsy...
, is sometimes used to treat severe chronic pain in the lower (
lumbarIn tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum ...
) back, where radio frequency waves are used to produce heat on specifically identified nerves surrounding the
facet jointsA zygapophysial joint is a synovial joint between the superior articular process of one vertebra and the inferior articular process of the vertebra directly above it...
on either side of the
lumbarIn tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum ...
spine. By generating heat around the nerve, its ability to transmit pain signals to the brain is destroyed, thus ablating the nerve. The nerves to be ablated are identified through injections of local anesthesia (such as
lidocaineLidocaine , Xylocaine, or lignocaine is a common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.- History :Lidocaine, the first amino...
) prior to the RFA procedure. If the
local anesthesiaLocal anesthesia is any technique to induce the absence of sensation in part of the body, generally for the aim of inducing local analgesia, that is, local insensitivity to pain, although other local senses may be affected as well. It allows patients to undergo surgical and dental procedures with...
injections provide temporary pain relief, then RFA is performed on the nerve(s) that responded well to the injections. RFA is a minimally invasive procedure which can usually be done in day-surgery clinics, where the patient is sent home shortly after completion of the procedure. The patient is awake during the procedure, so risks associated with general anesthesia are avoided. An
intravenousIntravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...
line may be inserted so that mild sedatives can be administered. The major drawback for this procedure is that nerves regenerate over time, so the pain relief achieved lasts for only a short duration (6–24 months) in most patients.
Other uses
RFA is also used in radiofrequency lesioning,
somnoplastySomnoplasty is composed of the Latin root somnus meaning sleep, and the Greek word plastia meaning molding or formation. Somnoplasty is a medical treatment approved by the Food and Drug Administration to treat three conditions: habitual snoring, chronic nasal obstruction, and obstructive sleep...
, and for vein closure in areas where intrusive surgery is contraindicated by trauma. Radiofrequency energy is also used in liver resection to control bleeding (hemostasis) and facilitate the transection process.
This process has also been used with success to treat TRAP sequence in multiple gestation pregnancies. This is becoming the leading method of treatment with a higher success rate for saving the 'pump' twin in recent studies than previous methods including laser photocoagulation. Due to the rarity of this complication, its correct diagnosis statistics are not yet reliable.
RFA is being investigated to treat
uterine fibroidsA uterine fibroid is a benign tumor that originates from the smooth muscle layer and the accompanying connective tissue of the uterus.Fibroids are the most common benign tumors in...
. A system developed by Halt Medical Inc. uses the heat energy of radio frequency waves to ablate the fibroid tissue. The device is inserted via a laparoscopic probe and guided inside the fibroid tissue using an ultrasound probe (see video demonstration
http://online.wsj.com/article/SB10001424052748704541004575010933671115028.html#video%3D4EEED67A-43A5-40DA-A45D-76FCC1279956%26articleTabs%3Dvideo).
See also
- Non-invasive RF cancer treatment
- Interventional radiology
Interventional radiology is a specialty of radiology, in which image-guided procedures are used to diagnose and treat a multitude of diseases across all body systems...
- Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
External links