Abstract: Objective To explore the diagnostic value of transesophageal echocardiography (TEE) in the left atrial and left atrial appendage thrombus before atrial fibrillation radiofreguency ablation treatment. Methods 52 cases of patients with atrial fibrillation received check of transthoracic echocardiography (TTE)and TEE, before radiofreguency ablation treatment, the situation of left atrial and left atrial appendage thrombus were summarized. Results In 52cases patients with TTE, left atrial thrombus were found in 4 case(7.69%), left atrial appendage thrombus in 3 case (5.77%), The false positive in 1of 3 cases, left atrial spontaneous echo contras (SEC)in 2 case (3.85%); In 52cases patients with TEE, left atrial thrombus were found in 8 cases (15.38%), left atrial appendage thrombus in 9(17.31%), left atrial SEC in 8(15.38%), left atrial appendage SEC in 6(11.54%). Every indice had statistically significantly in all patients between TEE and TTE.The Uitrasonic image of left atrial or left atrial appendage thrombus showed abnormal clumps echo attached to the wall. Swirling or cloudy signs which were explored in left atrium or left atrial appendage were SEC, It is hypercoagulable state. Conclusion The detection rate of left atrial and left arterial appendage thrombus is increasesed by TEE. It is a effective method before atrial fibrillation radiofreguency ablation treatment.

Key words: Transesophageal echocardiography, Atrial fibrillation, Left atrium, Left atrial appendage, thrombus, spontaneous echo contras