Atrioesophageal Fistula on Echocardiogram (a4c) Spontaneously appearing microbubbles during coughing. Left: normal breathing Right: during coughing Ivan Stankovic, MD, PhD @Ivan_Echocardio #atrial #Atrioesophageal #Fistula #a4c #Echocardiogram #clinical #cardiology #pocus