tailieunhanh - HANDBOOK OF CARDIAC PACING – PART 10

Chúng tôi vừa công bố trường hợp một nhân viên truyền hình cáp với một ICD người nắm lấy một dây cáp điện sống trong khi quỳ xuống một đường hầm tiện ích ẩm. Hiện tại AC đi qua cơ thể của ông ngăn chặn anh ta phát hành dây. ICD cảm nhận EMI như rung thất | 136 Handbook of Cardiac Pacing detection to occur. We recently published a case of a cable television worker with an ICD who grabbed a live power cable while kneeling in a damp utility tunnel. The AC current passed through his body preventing him from releasing the wire. The ICD sensed the EMI as ventricular fibrillation and shocked the man causing him to be thrown back and release the wire. Most oversensing caused by EMI is not as dramatic as this and is the result of strong electrical fields. A fractured lead or one with failed insulation is a common source of false signals. These leads produce large spurious signals that can be easily sensed by the ICD. If enough of these signals are present and fast enough detection will occur. As noted in the previous two sections pacemakers can interact with ICDs. Unipolar pacemakers and some bipolar pacemakers can be easily sensed by the ICD resulting in counting of the QRS the ventricular pacing pulse and even the atrial pacing pulse. This would result in the ICD seeing a double-sensed ventricular rate of 140 for a VVI paced rate of 70 and a triple-sensed ventricular rate of 210 for a DDD rate of 70. Corrective Action The detection rate of the ICD can be increased to avoid overdetecting sinus rates if possible. Occasionally beta blocker therapy may blunt the sinus rates enough to prevent this problem and may be used if tolerated by the patient. Otherwise addition of additional discrimination criteria such as sudden onset or QRS morphology may help if these features are available. The same is true for supraventricular arrhythmias. Ablation therapy of the arrhythmia or the AV-node may be an option in some patients as well. If a device interaction has occurred and reprogramming to a lower output and pulse width and or bipolar polarity is not possible a more appropriate pacing system may need to be implanted. In some situations the pacing leads may require repositioning. Lead failures and connection problems will require .