Radiofrequency ablation (RFA) is a medical procedure in which heat generated from medium frequency alternating current (in the range of 350–1 MHz) is used to selectively destroy dysfunctional tissue such as malfunctioning parts in the electrical conduction system of the heart, tumors, and sensory nerves. RFA is generally conducted in the outpatient setting, using either a local anesthetic or twilight anesthesia. When it is delivered via catheter, it is called radiofrequency catheter ablation. RFA also forms the basis behind electrosurgery.
Two advantages of medium frequency current (over previously used low frequency AC or pulses of DC) are that it does not directly stimulate nerves or heart muscle, and therefore can often be used without the need for general anesthesia, and that it is specific for treating the desired tissue without significant collateral damage. Due to this, RFA is an alternative for eligible patients who have comorbidities or do not want to undergo surgery.
Documented benefits have led to RFA becoming widely used during the 21st century. RFA procedures are performed under image guidance (such as X-ray screening, CT scan or ultrasound) by an interventional pain specialist (such as an anesthesiologist), interventional radiologist, otolaryngologists, a gastrointestinal or surgical endoscopist, or a cardiac electrophysiologist, a subspecialty of cardiologists.
Tumors
RFA may be performed to treat tumors in the lung,Daily Telegraph – June 2008 – Lung cancer radiation treatment offers new hope liver,BBC News- 16 January 2009 – Liver tumours 'microwaved away' kidney, and bone, as well as other body organs less commonly. 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, which results in destruction of the tumor. RFA can be used with small tumors, whether these arose within the organ (primary tumors) or spread to the organ (metastases). The suitability of RFA for a particular tumor depends on multiple factors.
RFA can usually be administered as an outpatient procedure, though may at times require a brief hospital stay. RFA may be combined with locally delivered chemotherapy to treat hepatocellular carcinoma (primary liver cancer). Phase III trials have tried using the low-level heat (hyperthermia) created by the RFA probe to trigger release of concentrated chemotherapeutic drugs from heat-sensitive liposomes in the margins around the ablated tissue as a treatment for hepatocellular carcinoma (HCC).Phase 3 Study of ThermoDox With Radiofrequency Ablation (RFA) in Treatment of Hepatocellular Carcinoma (HCC) Radiofrequency ablation is also used in pancreatic cancer and bile duct cancer.
RFA has become increasingly important in the care of benign bone tumors, most notably osteoid osteomas. Since the procedure was first introduced for the treatment of osteoid osteomas in the 1990s, it has been shown in numerous studies to be less invasive and expensive, to result in less bone destruction and to have equivalent safety and efficacy to surgical techniques, with 66 to 95% of people reporting freedom from symptoms. While initial success rates with RFA are high, symptom recurrence after RFA treatment has been reported, with some studies demonstrating a recurrence rate similar to that of surgical treatment. RFA is also increasingly used in the palliative treatment of painful metastatic bone disease in people who are not eligible or do not respond to traditional therapies ( i.e. radiation therapy, chemotherapy, palliative surgery, bisphosphonates or analgesic medications).
Cardiology
Radiofrequency energy is used in heart tissue or normal parts to destroy abnormal electrical pathways that are contributing to a cardiac arrhythmia. It is used in recurrent atrial flutter (Afl), atrial fibrillation (AF), supraventricular tachycardia (SVT), atrial tachycardia, Multifocal Atrial Tachycardia (MAT) 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 study) before the responsible tissue is eliminated. Radiofrequency ablation technique can be used in AF, either to block the atrioventricular node after implantation of a pacemaker or to block conduction within the left atrium, especially around the pulmonary veins. Radiofrequency ablation for AF can be unipolar (one electrode) or bipolar (two electrodes). Although bipolar can be more successful, it is technically more difficult, resulting in unipolar being used more often. But bipolar is more effective in preventing recurrent atrial arrhythmias.
Ablation is now the standard treatment for SVT and typical atrial flutter. In some conditions, especially forms of intra-nodal re-entry (the most common type of SVT), also called atrioventricular nodal reentrant tachycardia or AVNRT, ablation can also be accomplished by cryoablation (tissue freezing using a coolant which flows through the catheter); this avoids the risk of complete heart block, a potential complication of radiofrequency 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, and laser ablation have also been developed but are not in widespread use.
Renal sympathetic denervation
A new indication for the use of radiofrequency technology has made news in the last few years. Hypertension is a very common condition, with about 1 billion people over the world, nearly 75 million in the US alone. Complications of inadequately controlled hypertension are many and have both individual and global impact. Treatment options include medications, diet, exercise, weight reduction and meditation. Inhibition of the neural impulses that are believed to cause or worsen hypertension has been tried for a few decades. Surgical sympathectomy has helped but not without significant side effects. Therefore, the introduction of non-surgical means of renal denervation using a radiofrequency ablation catheter was enthusiastically welcomed. Although the initial use of radiofrequency-generated heat to ablate nerve endings in the renal arteries to aid in management of 'resistant hypertension' were encouraging, the most recent phase 3 studying looking at catheter-based renal denervation for the treatment of resistant hypertension failed to show any significant reduction in systolic blood pressure.
Aesthetics dermatology Radiofrequency ablation is also used in dermatosurgical applications in the form of electrosurgery. Depending on the output waveform used, different modes of ablation can be achieved, including are electrosection (cutting), electrocoagulation, electrodessication and fulguration. The use of radiofrequency ablation has obtained importance as it can be used to treat most of the skin lesions with minimal side effects and complications.
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 vein, the small 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 phlebectomy, sclerotherapy, or foam sclerotherapy. Currently, the VNUS ClosureRFS stylet is the only device specifically cleared by FDA for endovenous ablation of perforator veins.Endovenous ablation of perforator veins
The possibility of skin burn during the procedure is very small, because the large volumes (500 cc) of dilute Lidocaine (0.1%) tumescent anesthesia injected along the entire vein prior to the application of radiofrequency provide a heat sink that absorbs the heat created by the device. Early studies have shown a high success rate with low rates of complications.
Obstructive sleep apnea
RFA was first studied in obstructive sleep apnea (OSA) in a pig model. RFA has been recognized as a somnoplasty treatment option in selected situations by the American Academy of Otolaryngology but was not endorsed for general use in the American College of Physicians guidelines.
The clinical application of RFA in obstructive sleep apnea is reviewed in that main article, including controversies and potential advantages in selected medical situations. Unlike other electrosurgical devices, RFA allows very specific treatment targeting of the desired tissue with a precise line of demarcation that avoids collateral damage, which is crucial in the head and neck region due to its high density of major nerves and blood vessels. RFA also does not require high temperatures. However, overheating from misapplication of RFA can cause harmful effects such as coagulation on the surface of the electrode, boiling within tissue that can leave "a gaping hole", tears, or even charring.
Pain management Back RFA, or rhizotomy, was developed by Nikolai Bogduk to treat chronic pain arising from the facet joints in the lower (lumbar) back. Radiofrequency waves are used to produce heat on specifically identified nerves surrounding the facet joints called the lumbar medial branches of the dorsal ramus of the spinal nerves. By generating heat around the nerve, the nerve is ablated, thus destroying its ability to transmit signals to the brain.
The nerves to be ablated are identified through injections of local anesthesia (such as lidocaine) around the medial branches prior to the RFA procedure to first confirm the diagnosis. If the local anesthesia injections provide temporary pain relief, the injection is repeated a second time to confirm the diagnosis. 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, going home shortly after completion of the procedure. The person is awake during the procedure, so risks associated with general anesthesia are avoided. Whether for back or knee pain, a drawback for this procedure is that nerves recover function over time, so the pain relief achieved lasts only temporarily (3–15 months) in most people.
Knees
Radiofrequency ablation of sensory nerves in the knee, also called genicular neurotomy or genicular RFA, is clinically preceded by confirming pain reduction upon anesthetizing the main knee sensory nerves in a test procedure called genicular nerve block. Genicular nerve block is a short (10–30 minutes), outpatient procedure usually performed weeks before genicular RFA. The extent of pain reduction by injecting a local anesthetic, such as bupivacaine, at specific locations of the target genicular nerves, is self-assessed by the person for hours after the procedure, leading to confirmation with the physician of the need for RFA.
In the procedure for genicular RFA, a guide cannula is first directed under local anesthesia and imaging (ultrasound or fluoroscopy) to each target genicular nerve, then the radiofrequency electrode is passed through the cannula, and the electrode tip is heated to about for one minute to cauterize a small segment of the nerve. The heat destroys that segment of the nerve, which is prevented from sending pain signals to the brain.