Hai vấn đề lớn gây ra bởi thuốc chống loạn nhịp được rằng họ có thể thay đổi năng lượng cần thiết cho việc khử rung tim thành công và họ có thể thay đổi các đặc điểm của chứng loạn nhịp tim được điều trị. | 128 Chapter 9 Table Effect of antiarrhythmic drugs on pacing thresholds Increase at normal drug levels Increase at toxic drug levels No increase Flecainide Propafenone Amiodarone Sotalol Quinidine Procainamide Disopyramide Lidocaine Mexiletine several ways and is often clinically significant. Two major problems caused by antiarrhythmic drugs are that they can change the energy required for successful defibrillation and they can change the characteristics of the arrhythmia being treated. The effect of antiarrhythmic drugs on defibrillation energy requirements is an important consideration because increasing the defibrillation threshold can render an ICD ineffective. The effects of various drugs on defibrillation energy requirements are summarized in Table . In general drugs that block the sodium channel increase defibrillation energy requirements thus Class IC drugs have the most profound effect and Class IA and Class IB drugs tend to have proportionally lesser effects and drugs that block the potassium channels . sotalol decrease defibrillation energy requirements. Drugs that affect both the sodium and potassium channels . Class IA drugs and amiodarone have mixed effects sometimes they increase and sometimes they decrease defibrillation energy requirements. If one must prescribe a drug that has the potential of increasing defibrillation energy requirements for a patient who has an ICD one should consider retesting defibrillation thresholds after the drug has been loaded to be sure that the ICD is still capable of delivering sufficient energy to reliably defibrillate the patient. Antiarrhythmic drugs can also interact with ICDs by changing the characteristics of a patient s ventricular tachycardia. By slowing the Table Effect of antiarrhythmic drugs on defibrillation thresholds Increase Mixed effect Decrease Flecainide Quinidine Sotalol Propafenone Lidocaine Mexiletine Procainamide Amiodarone Common adverse events with antiarrhythmic drugs 129 rate
