Pacing systems sources

Skeletal muscle myopotential over-sensing. Unipolar pacing systems are far more susceptible to skeletal myopotential sensing and consequent inhibition than are bipolar systems. Such inhibition represents the most common source of unipolar over-sensing (5) particularly in the atrium, because of the necessity to use high sensitivity settings. 

Fig. 19.16 The Medtronic 9790 programmer generates a uniform amplitude pacemaker spike in response to any high-frequency transient. Although the paced rhythm can be seen in the background, the multiple pacing stimuli are arising from an unknown source extrinsic to the pacemaker and distorted the recording markedly impeding the pacing system evaluation.

Figure 1 Representation of a bilateral pacing system. Note the following components—transmitter, antenna, receiver, and electrode. Source From Avery Biomedical Devices.

The system evolves with the innermost orbit receding from the central body (because of the non-conservative forces acting on mi) up to the moment where the system is captured into a resonance, a2 is almost constant. When the 2/f-resonance is reached, the system is trapped by the resonance. As known since Laplace, after the capture, mi continuously transfers one fraction of the energy that it is getting from the non-conservative source to m2, so that 02 also increases. One may note from Figure 9 that, after the capture into the resonance, ai increases at a smaller pace than before the capture. The increase of the semi-major axes is such that the ratio ai/a2 remains constant. 

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