Gần đây đã chỉ ra rằng nhịp tâm thất trong ICD-điều trị bệnh nhân rối loạn chức năng tâm thất trái có thể có hại cho nó có thể đóng góp cho tâm thất co dys-đồng bộ với tăng nguy cơ tử vong và suy tim | Implantable devices 231 It has recently been shown that ventricular pacing in ICD-treated patients with left ventricular dysfunction may be detrimental for it can contribute to dys-synchronous ventricular contraction with increased risk for death and heart failure 79 . In ICD-treated patients without an indication for bradycardia support every effort should be made to avoid unnecessary ventricular pacing by programming the pacing component of the ICD to a slow ventricular-demand back-up pacing rate of approximately 40 ppm. Routine patient follow-up with device interrogation and reprogramming as necessary should be carried out every 4 months. At the present time generator replacement for battery depletion is required at approximately 5-year intervals. Conclusions A substantial numberof patients with ischemic and nonischemic cardiomyopathy have now been studied in randomized clinical trials in which the ICD has been compared with conventional medical therapy. The vast majority of these patients have compromised left ventricular systolic function as manifested by an ejection fraction below . ICD is effective and safe therapy for improving survival through the reduction of sudden cardiac death with overall reduction in mortality in the range of 30 during an average follow-up of approximated 2 years. As a general rule the sicker patients achieve greater benefit from ICD therapy. References 1. Elmqvist R Senning A. Implantable pacemaker lot the heart. In Smyth ex ed. Medical Electronics. Proceedings of the Second International Conference on Medical Electronics Paris June 24-27 Tliffe and Sons London UK 1959 1960 253-254. 2. Roe BB Katz HJ. Complete heart block with intractable asystole and recurrent ventricular fibrillation with survival. Am J Cardiol 1965 15 401-403. 3. Lawrence GH King RL Paine RM Spencer MP Hughes ML. Complete heart block. Patient selection and response to implantation of electronic pacemaker. JAMA 1964 190 1093-1098. 4. Edhag O Swahn A. Prognosis
