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Pacemaker failure is the inability of an implanted artificial pacemaker to perform its intended function of regulating the beating of the heart. It is defined by the requirement of repeat surgical pacemaker-related procedure after the initial implantation. A study of pacemaker failure in Oregon in the 1970s indicates that 10% of implanted pacemakers failed within the first month. Causes of pacemaker failure included: lead related failure (lead migration, lead fracture, ventricular perforation), unit malfunction (battery failure or component malfunction), problems at the insertion site (infections, tissue breakdown, battery pack migration), failures related to exposure to high voltage electricity or high intensity microwaves, and a miscellaneous category (one patient had ventricular tachycardia when using his electric razor and another patient had persistent pacing of the diaphragm muscle).〔 〕 ==Causes== Many devices interfere with pacemakers causing failure: * Power-generating equipment, arc welding equipment and powerful magnets (as in medical devices, heavy equipment or motors) can inhibit pulse generators. Patients who work with or near such equipment should know that their pacemakers may not work properly in those conditions.〔(【引用サイトリンク】url=http://www.americanheart.org/presenter.jhtml?identifier=4676 )〕 * With the advances of technology, Federal Communications Commission (FCC) is making new frequencies available. Newer cellphones using these new frequencies might make pacemakers less reliable. A group of cellphone companies is studying that possibility.〔 * Equipment used by doctors and dentists can affect pacemakers.〔 * Magnetic resonance imaging (MRI) uses a powerful magnet to produce images of internal organs and functions. Metal objects are attracted to the magnet and are normally not allowed near MRI machines. The magnet can interrupt the pacing and inhibit the output of pacemakers. If MRI must be done, the pacemaker output in some models can be reprogrammed.〔 In February 2011, the FDA approved an MRI-safe pacemaker. * Extracorporeal shock-wave lithotripsy (ESWL) procedure is safe for most pacemaker patients, with some reprogramming of the pacing. Careful follow-up after the procedure is required. Patients with certain kinds of pacemakers implanted in the abdomen should avoid ESWL.〔 * Diagnostic radiation (such as screening X-ray) appears to have no effect on pacemaker pulse generators. However, therapeutic radiation (such as for treating cancerous tumors) may damage the pacemaker's circuits. The degree of damage is unpredictable and may vary with different systems. But the risk is significant and builds up as the radiation dose increases. The American Heart Association recommends that the pacemaker be shielded as much as possible, and moved if it lies directly in the radiation field.〔 * Short-wave or microwave diathermy uses high-frequency, high-intensity signals. These may bypass pacemaker's noise protection and interfere with or permanently damage the pulse generator.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pacemaker failure」の詳細全文を読む スポンサード リンク
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