There are a number of possible methods to create an appropriately sized lesion in the heart without causing too much damage to surrounding tissues. Radiofrequency (RF) treatment is the most commonly used method, involving the transmission of radio wave energy to cauterize a small section of heart tissue. Cryoablation creates a lesion by cooling tissue near the catheter tip to a temperature low enough to kill the cells. In addition, cryoablation catheters can be used for performing site testing by temporarily blocking electrical conductivity through a specific area of tissue without permanently destroying the cells involved. Laser ablation involves the use of a laser wand to create a lesion in a manner similar to that of RF ablation. However, in laser ablation, no physical contact between the tissue and the wand would be required, reducing the risk of certain complications. Microwave cardiac ablation functions in the same manner as RF ablation, but its development was abandoned by Boston Scientific after early trials showed a low long-term success rate. High intensity focused ultrasound (HIFU) cardiac ablation involves the use of precisely focused ultrasound to permanently disrupt electrical transmission in selected cardiac tissue. Theoretically, this procedure can be performed thoracoscopically, making it less invasive than most surgical procedures. In addition, because the HIFU energy is beamed from outside the heart, there is a lower risk of damage to peripheral areas. This treatment modality was developed by ProRhythm Inc., but the company dissolved in 2008 and their intellectual property was acquired by Misonix Inc. and Philips Medical. St. Jude Medical has developed the Epicor Medical HIFU cardiac ablation system; however, it is not available for sale in the U.S. at the time of writing.