The target of this thesis is to discuss the critical care experience for an Arrhythmic patient who needs Cardioversion staying in ICU. The nursing period started from 31 Aug 2008 to 18 Sep 2008. The writer has collected the information of patient through the observation, body assessment and interview with family. Besides, the Gordon's 11 Functional Health Patterns has been used for assessment. The identified health problems include: (1) decreased cardiac output/ ventricular tachycardia; (2) impaired skin integrity/ Cardioversion; (3) anxiety/ Cardioversion and death risk. Under the effort of medical team, individual nursing measure has been provided to patient in order to maintain the normal cardiac output, preserving the skin integrity and reducing the death anxiety caused by Cardioversion. Finally, the patient's condition has been improved and he could leave the ICU. It is expected this report can be the reference for nursing personnel in ICU taking care similar cases in future.