Invasive electrophysiological studies, in which wires are passed through a vein to stimulate and record electrical signals from the heart, can sometimes be used to assess the risk of a person with Brugada syndrome experiencing dangerous abnormal heart rhythms.[24] Risk stratification is also sometimes performed using a signal averaged ECG.[2] Ambulatory ECG monitoring, including implantation of a loop recorder, is sometimes used to assess whether dizziness or faints in a person with Brugada syndrome are due to abnormal heart rhythms or other causes such as vasovagal syncope.[25]