OBJECTIVE To discuss the necessity and the related technical details of device upgrade from VVI(R) to DDD(R), and primarily explore the adaption objects and the opportunity of the hardware optimization.

• 目的 探讨VVI(R)起搏改植为DDD(R)起搏的必要性和相关技术细节，初步探索起搏系统硬件优化的适应对象及手术时机。