ballistocardiograph, cardiograph - a medical instrument that measures the mechanical force of cardiac contractions and the amount of blood passing through the heart during a specified period by measuring the recoil of the body as blood is pumped from the ventricles

cardiograph, electrocardiograph - medical instrument that records electric currents associated with contractions of the heart

monitor - a piece of electronic equipment that keeps track of the operation of a system continuously and warns of trouble

cathode-ray oscilloscope, CRO, oscilloscope, scope - electronic equipment that provides visual images of varying electrical quantities