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[The modification of programmable pacemakers by therapeutic irradiation]
M Wilm1, H L Kronholz, J Schütz
1Klinik und Poliklinik für Strahlentherapie, Abteilung Radioonkologie, Westfälische Wilhelms-Universität Münster.
Background:
More than 300,000 pacemakers are implanted worldwide. During radiation therapy a damage of the pacemaker electronic is possible.
Methods:
Twenty pacemakers have been irradiated with photons or electrons experimentally in three different situations: a) pacemaker and pacemaker electrode outside of the irradiation field: b) pacemaker outside, pacemaker electrode inside the irradiation field; c) all things inside the irradiation field.
Results:
The voltage in the pacemaker electrode produced by the electric field of the accelerator did not exceed 0.8 mV if the electrode was outside the irradiation field. Induced voltage was up to 1.2 mV during irradiation with electrons (18 MeV) and the electrode being inside the treatment field with more than two thirds of its length. After delivering of not more than 10 Gy (photons) to the pacemaker, a decreasing amplitude of the pacemaker pulse occurred. The pulse frequency did not show any deviation. This seems to signal a severe early irreversible damage of the pacemaker that may cause sudden breakdown days or weeks after radiation. Two pacemakers showed a complete breakdown after irradiation with not more than 10 Gy. The others had a complete breakdown beyond doses of 50 Gy.
Conclusions:
It is recommended to keep CMOS pacemakers outside the treatment field and to explant if the dose to it was higher than 10 Gy.