| Radiofrequency ablation | |
|---|---|
| Intervention | |
| ICD-9-CM | 01.32, 04.2, 37.33, 37.34, 60.97 |
| MeSH | D017115 |
Radio frequency ablation (RFA) is a medical procedure where part of the electrical conduction system of the heart, tumor or other dysfunctional tissue 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.[1][2] 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 or a cardiac electrophysiologist, a subspecialty of cardiologists.
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RFA is performed to treat tumors in lung,[3][4][5] liver,[6] 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 (metastasis). 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 carcinoma (HCC).[7] Radiofrequency ablation is also used in Pancreatic cancer and bile duct cancer [8]
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 flutter, atrial fibrillation (AF), supraventricular tachycardia (SVT), atrial tachycardia 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. 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 node after implantation of a pacemaker or to block conduction within the left atrium, 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 cryoablation (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 [9]. 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 Blair underwent RF catheter ablation for recurrent atrial flutter.[10][11]
In AF, the abnormal electrophysiology can also be corrected surgically. This procedure referred to as the "Cox maze procedure", is mostly performed concomitantly with cardiac surgery.
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 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.
RFA, or rhizotomy, is sometimes used to treat severe chronic pain in the lower (lumbar) back, where radio frequency waves are used to produce heat on specifically identified nerves surrounding the facet joints on either side of the lumbar 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 lidocaine) prior to the RFA procedure. If the local anesthesia 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 intravenous 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[12]) in most patients.
RFA is also used in radiofrequency lesioning, somnoplasty, 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 fibroids. A system developed by Halt Medical Inc. uses the heat energy of radio frequency waves to ablate the fibroid tissue.[13] The device is inserted via a laparoscopic probe and guided inside the fibroid tissue using an ultrasound probe (see video demonstration [2]).