Tong-yuan Zhang, et al. flecting the relative and absolute changes between the sym- pathetic and parasympathetic components of the autonomic nervous system. Wiklund, et al.12 also found that after sympathotomy LF power was reduced, but HF power did not change. In addi- tion, they observed that LF power remained at a lower lev- el, while HF power was reduced at follow-up, approximate- ly six months later. They came to the conclusion that sympathotomy resulted in an initial sympathovagal change with parasympathetic predominance, which was restored on a long-term basis. These observations also support the sympatholytic effect of the surgical procedure. A few studies have shown significant effects for thoracic sympathotomy on cardiac and pulmonary function vari- ables. Cruz, et al.13 observed a statistically significant de- crease in forced expiratory flow,14 airway resistance in small airways, an increase in residual volume, and a significant decrease in heart rate and ejection fraction, even though the parameters were all in normal ranges. Nakamura, et al.15 verified that HR and arterial blood pressure decreased at rest and during submaximal treadmill exercise after R2-R3 endoscopic transthoracic sympathotomy. In addition, they also identified an increase in plasma adrenaline and nor- adrenaline after ETS. Tedoriya, et al.16 found that responses to the sympathetic stress were suppressed by ETS. The car- diopulmonary effects of ETS are probably a consequence to the removal of the R2 to R4 adrenergic cardiopulmonary efferent or afferent section during surgery. In summary, there was a significant improvement in HRV in patients with palmar hyperhidrosis disease after thoracic sympathotomy. This may contribute to a shift in sympa- thovagal unbalance toward parasympathetic dominance in the early stage after endoscopic transthoracic sympathoto- my. The lack of long-term follow-up and the measurement of plasma catecholamine concentration are limitations of our study. Further study should be taken to identify the value of HRV as a predictor of long-term treatment effects. REFERENCES 1. Solish N, Bertucci V, Dansereau A, Hong HC, Lynde C, Lupin M, et al. A comprehensive approach to the recognition, diagnosis, and severity-based treatment of focal hyperhidrosis: recommendations of the Canadian Hyperhidrosis Advisory Committee. Dermatol Surg 2007;33:908-23. 2. Bejarano B, Manrique M. [Thoracoscopic sympathectomy: a liter- ature review]. Neurocirugia (Astur) 2010;21:5-13. 3. García-Franco CE, España A. [Usefulness of bilateral sympathec- tomy using video-assisted thorascopic surgery in the treatment of essential hyperhidrosis]. Actas Dermosifiliogr 2008;99:523-7. 4. Senard JM, Simonetta-Moreau M, Tran MA. Blood pressure and heart rate variability in patients with essential hyperhidrosis. Clin Auton Res 2003;13:281-5. 5. Tortora GJ, Nielsen M. Principles of human anatomy. 11th ed. J. Wiley, NJ: Hoboken; 2009. 6. Kleiger RE, Stein PK, Bigger JT Jr. Heart rate variability: mea- surement and clinical utility. Ann Noninvasive Electrocardiol 2005;10:88-101. 7. Vanderlei LC, Pastre CM, Hoshi RA, Carvalho TD, Godoy MF. Basic notions of heart rate variability and its clinical applicability. Rev Bras Cir Cardiovasc 2009;24:205-17. 8. Kingma R, TenVoorde BJ, Scheffer GJ, Karemaker JM, Mackaay AJ, Wesseling KH, et al. Thoracic sympathectomy: effects on he- modynamics and baroreflex control. Clin Auton Res 2002;12:35- 42. 9. Prasad A, Ali M, Kaul S. Endoscopic thoracic sympathectomy for primary palmar hyperidrosis. Surg Endosc 2010;24:1952-7. 10. Heart rate variability: standards of measurement, physiological in- terpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Circulation 1996;93:1043-65. 11. Zhang B, Li Z, Yang X, Li G, Wang Y, Cheng J, et al. Anatomical variations of the upper thoracic sympathetic chain. Clin Anat 2009;22:595-600. 12. Wiklund U, Koskinen LO, Niklasson U, Bjerle P, Elfversson J. Endoscopic transthoracic sympathicotomy affects the autonomic modulation of heart rate in patients with palmar hyperhidrosis. Acta Neurochir (Wien) 2000;142:691-6. 13. Cruz JM, Fonseca M, Pinto FJ, Oliveira AG, Carvalho LS. Car- diopulmonary effects following endoscopic thoracic sympathecto- my for primary hyperhidrosis. Eur J Cardiothorac Surg 2009;36: 491-6. 14. Ponce González MA, Julià Serdà G, Santana Rodríguez N, Rodrí- guez Suárez P, Pérez Peñate G, Freixinet Gilart J, et al. Long-term pulmonary function after thoracic sympathectomy. J Thorac Car- diovasc Surg 2005;129:1379-82. 15. Nakamura Y, Fujimoto M, Nagata Y, Shiraishi K, Yoshizawa H, Kida H, et al. Effects of endoscopic transthoracic sympathicotomy on hemodynamic and neurohumoral responses to exercise in hu- mans. Circ J 2002;66:357-61. 16. Tedoriya T, Sakagami S, Ueyama T, Thompson L, Hetzer R. In- fluences of bilateral endoscopic transthoracic sympathicotomy on cardiac autonomic nervous activity. Eur J Cardiothorac Surg 1999;15:194-8. 1084 Yonsei Med J http://www.eymj.org Volume 53 Number 6 November 2012