The term 'rapid irregular heart beat' is a medical condition known as palpitations (11 letters). Palpitations are characterized by an abnormally fast or irregular heartbeat, which can be caused by a variety of factors such as stress, anxiety, or certain medications. Symptoms may include a feeling of fluttering or pounding in the chest, shortness of breath, dizziness, and chest pain. Palpitations can be a sign of a serious medical condition, so it is important to seek medical attention if they occur.