RF energy is delivered to the tissue between the jaws of the clamp at 75 volts and 750 milliamps (mA).20 The RF generator monitors voltage, current, temperature, time, and tissue conductance. Energy delivery is continued until tissue conductance between electrodes in the jaws of the clamp decreases and reaches a steady state for 2 seconds.21,22 Current studies have found that bipolar radiofrequency is superior to unipolar radiofrequency.19,21 Bipolar RF is able more consistently to create transmural lesions especially when working only with the ablation of Inhibitors,research,lifescience,medical the pulmonary veins since the shape of the clamp

allows easy placement around the pulmonary veins. Endocardial blood flow has also not been shown to influence the ablation lesion depth.22 Microwave and ultrasound energy sources have been used as well in surgical ablation.23 Inhibitors,research,lifescience,medical However, studies have shown that these energy sources in the current state do not create transmural lesions consistently so the long-term efficacy in achieving a return to sinus rhythm is very low.20,21 In fact, the Federal Food and Drug Administration (FDA) recently removed its approval for the use of ultrasound in surgical ablation procedures. ABLATION PROBES Table 1 displays the ablation probes that are in use today. The cryothermy probes are produced by Medtronic (Minneapolis, MN, USA),

and the radiofrequency probes are produced by Atricure (Schiphol, The Netherlands) (Figure 1).15,16 Inhibitors,research,lifescience,medical The Cardioblate® CryoFlex™ Surgical Ablation System is Inhibitors,research,lifescience,medical intended for minimally invasive Bcl-xL apoptosis cardiac surgical procedures, including the treatment of cardiac arrhythmias. The Cardioblate CryoFlex 7-cm, 10-cm, and 10-S probes plus the Cardioblate CryoFlex Clamp and Cardioblate CryoFlex Surgical

Ablation Console freeze target tissue and block the electrical conduction pathways by creating an inflammatory response Inhibitors,research,lifescience,medical and cryonecrosis. Atricure developed a new cryoprobe that is being used with the nitric oxide platform; the new probe is semi-flexible and can be used to apply all lesions required for the maze procedure. Unlike the CryoFlex, the Cryo1 probe has a defrost feature that facilitates quick removal of the probe from the tissue (Figure 2). All ablation devices may induce complications due to their potential damage the cardiac tissue.15,16 Table 1 Ablation Devices. Photos courtesy of the respective manufacturers. however Figure 1 Atricure®Radiofrequency Ablation Probe. Figure 2 Atricure®CryoFlex Probe 1. Estech (San Ramon, CA, USA), a leader in minimally invasive and endoscopic cardiac ablation, has recently gained FDA conditional Investigational Device Exemption (IDE) approval to start a trial study (Figure 3). The IDE trial has been designed to evaluate the treatment of atrial fibrillation (AF) utilizing a multiple temperature-controlled radiofrequency (TCRF) device used to treat non-paroxysmal AF. The Estech device is called the COBRA® Surgical System.