Intracardiac and surface ECG recordings during electrophysiologic study in a person with atrial fibrillation

Three surface ECG leads (I, aVF, V1) and intracardiac recordings from the atrioventricular unction region (HBE1-2, HBE3-4), and the right ventricular apex (RVA3-4) in a patient with atrial fibrillation. The patient has extremely symptomatic, medically refractory atrial fibrillation with rapid ventricular rates and recurrent heart failure. The mapping catheter (HBE) has been maneuvered from the area of maximal His bundle activity to a more proximal position, where a larger atrial (A) and smaller His electrogram (H) are recorded.