**5. Conclusions**

Recently, the conventional cut-and-sew Cox-Maze procedure has been replaced by alternative energy sources in the surgical treatment of atrial fibrillation. Cryoablation and radiofrequency ablation have been playing an important role in this field. Both energy sources have been shown to be effective in treating atrial fibrillation. However, despite the technological advancement, there remains uncertainty of transmurality in human tissue, especially when patients have underlying disease. Lack of transmurality may result in failure of surgical ablation. Further histopathological studies will be necessary in assessing the effectiveness of using alternative energy sources. Moreover, a further technological advancement in achieving reliable transmurality should be warranted in the future.

## **Author details**

Takashi Murashita

Address all correspondence to: tmurashita@gmail.com

West Virginia University, Heart and Vascular Institute, Morgantown, WV, USA
