Technical and clinical problems in patients with simultaneous implantation of a cardiac pacemaker and spinal cord stimulator.

Spinal cord stimulators are used to relieve pain associated with peripheral ischemia and angina pectoris. In patients with both permanent pacemaker (PPM) and a spinal cord stimulator (SCS), electromagnetic signals from the SCS may inhibit the PPM. A bipolar PPM configuration is preferred to minimize myopotential or electromagnetic interference but patients have safely had unipolar devices implanted. We report ten patients (six males and four females; median age 73.3 years) with both a SCS and a PPM implanted between 1987-1991. Intermittent interference with one PPM (Ela Medical Model Opus 3001) was noted after an increase in the output voltage of the SCS for continued clinical efficacy. Inhibition was output voltage dependent, and reversion to the noise mode was frequency dependent. Sensitivity to both could be managed by changing the pacemaker sensitivity. Interference with pacemaker function occurred if the SCS output was set above a voltage and pulse duration which resulted in a product of these values above 1.9-2 mVs. Seven VVI, one VDD, and two DDD PPM had been implanted. In five patients both PPM and SCS were unipolar. In two patients the SCS was bipolar and the PPM unipolar, in two patients a bipolar PPM was associated with a bipolar SCS and with one patient, a unipolar SCS. Multiprogrammable and/or bipolar PPMs should be implanted in a patient with a SCS to allow reprogramming of the PPM and to minimize the risk of inter-device interference. Inhibition of the PPM may occur at different SCS stimulation frequencies. The frequency at which inhibition occurs varies with different models of implanted pacemaker.