Portable electrocardiography. Torso of a man attached to a portable ECG (electrocardiograph) machine. On his arm (lower left) is the grey inflatable cuff of a sphygmomanometer for measuring blood pressure. Electrodes attached to his chest pick up his heart's electrical signals and transmit them down to the ECG machine (not seen). The signals indicate the rate and regularity of the heart's contractions, allowing the health and functioning of the heart to be studied. Signals that deviate significantly from accepted healthy values may be a sign of heart disease. Portable ECG machines offer a quick and easy way to monitor a patient's heart.