Sensors of rate responsive pacing

This document discusses different sensor types for rate responsive pacing, including activity sensors, metabolic sensors, and dual sensors. It notes that fixed rate pacing is insufficient for patients with heart failure as it does not account for changes needed during exercise or recovery. Various metabolic and motion-based sensors are able to detect changes in oxygen demand and trigger a heart rate increase, such as sensors measuring venous oxygen saturation, pH, QT interval, body motion, respiratory rate, stroke volume, temperature, and minute ventilation. No single sensor can mimic the sinus node under all conditions, so dual sensors are often used in pacemakers to optimize rate response for daily activities.