US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic lower extremity arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54].
Workup of Noncerebral Systemic Arterial Embolic Source. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic lower extremity arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54].