pacemaker(redirected from runaway pacemaker)
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1. Anatomy a small area of specialized tissue within the wall of the right atrium of the heart whose spontaneous electrical activity initiates and controls the beat of the heart
2. Med an electronic device for use in certain cases of heart disease to assume the functions of the natural cardiac pacemaker
A pulsed battery-operated oscillator implanted in the body to deliver electric impulses to the muscles of the lower heart, either at a fixed rate or in response to a sensor that detects when the patient's pulse rate slows or ceases. Also known as cardiac pacemaker; heart pacer.