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Unformatted text preview: Biventricular Pacing – Pacemaker Battery Power Consumption Michael P. Breninford Introduction Power consumption in pacemakers can be divided into four major components: quiescent or standby current, pacing current, inhibited current, and maintenance current. Standby current is present so long as the device is powered and is fairly constant regardless of whether or not the device is performing any functions. Pacing current is dependent on various factors such as pacing frequency, output pulse amplitude and duration, and the type of load, i.e. lead driven by the pacemaker outputs. Inhibited currents are due to power consumption during sensing. Finally, maintenance power consumption is due to the use of built-in facilities such as telemetry, reprogramming, and diagnostic functions 1,2,3,4,5,6 . Advances in semiconductor fabrication have enabled integrated circuit (IC) designers to create circuits that are capable of operating at low supply voltages and consume very little current. Modern semiconductor devices enjoy lower static and dynamic power consumption. Dynamic power consumption is proportional to capacitive loading, operating frequency, and voltage squared. Therefore, a lower operating voltage results in significant reduction in static and dynamic power. Modern pacemakers not only benefit from advancements in lower power integrated circuit design but also from improved lead design. Higher impedance electrodes have resulted in lower pacemaker current drain and prolonged battery life 2,5,6 . Power Consumption in Modern Pacemakers The following table lists typical parameters used to calculate pacemaker power consumption and battery longevity. Table 1. Key Pacemaker Power Calculation Parameters and Values 5 Parameter Description Value Type Unit Symbol Battery Type Lithium-Iodide Battery cell capacity 1.2 ± 0.24 Ahr Bat Ahr Battery Parameters Battery Voltage...
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- Fall '07