Pulmonary arteriovenous malformation (PAVM) is a rare cause of embolic stroke of undetermined source (ESUS) and can be challenging to diagnose promptly. In this case, a woman in her 40s with ESUS was diagnosed with PAVM after a transoesophageal echocardiography (TOE) microbubble test revealed bubbles flowing from the right superior pulmonary vein. Endovascular treatment was performed, and follow-up transthoracic echocardiography showed no right-to-left shunt, confirming successful shunt closure. This case is significant as it is the first reported instance where both treatment and postoperative evaluation of PAVM were conducted using echocardiography. The early detection of the shunt through the microbubble test, within three cardiac cycles, was crucial and differs from typical delayed shunt detection. This suggests that focused imaging during TOE can enhance diagnostic accuracy for PAVM.