A device for monitoring the heart of a patient including a housing, a computing device, an optical sensor adapted to provide signals to the computing device indicative of a distance from the optical sensor to a vessel carrying blood, as well a diameter of the vessel, a Doppler sensor adapted to provide signals to the computing device indicative of a velocity of the blood through the vessel, and an ECG sensor adapted to provide signals to the computing device indicative of a plurality of electrical stimuli that cause the heart to pump. The computing device uses signals from the optical sensor, the Doppler sensor, and the ECG sensor to compute parameters including oxygen saturation of the blood, blood flow, blood pressure, heart rate, and cardiac output.
