A pacemaker is provided. The pacemaker includes a pulse generator and an electrode line connecting with the pulse generator. The electrode line includes a conductor, an insulation layer and a shielding layer. The insulation layer is located on an outer surface of the conductor. The shielding layer is located on an outer surface of the first insulation layer. The shielding layer is a carbon nanotube structure having a plurality of radioactive particles therein.
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