Role of Intraoperative Transesophageal Echocardiography for Diagnosing and Managing Pulmonary Embolism in the Perioperative Period

To the Editor: We read with great interest the excellent case report by Lu et al. describing a patient who experienced a pulmonary embolism (PE) in the perioperative period and was successfully treated with pulmonary embolectomy (1). Rapid and accurate diagnosis was crucial in the management of this patient, as it led to the institution of a successful therapy and a good outcome. The definitive diagnosis of acute PE was obtained by transesophageal echocardiography (TEE) via direct visualization of thrombotic material within the right and left atrium. Accordingly, the authors state that TEE is of great value in the setting of sudden intraoperative cardiovascular collapse and suspected PE. We fully agree with the authors that TEE is considered a primary diagnostic technique in patients with hemodynamic collapse due to its high availability and outstanding practicality in the perioperative setting (2). It is relatively noninvasive (3) and does not interfere with resuscitation efforts (4). In addition, practice guidelines developed by the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists highly recommend TEE for diagnosis and management of acute, life-threatening intraoperative hemodynamic collapse (5). However, the accuracy of TEE for directly diagnosing thromboemboli within the pulmonary artery may be limited. We recently reviewed TEE examinations of 46 patients with known PE and hemodynamic compromise who underwent urgent pulmonary embolectomy. Surprisingly, echocardiographic evidence for the presence of PE was correctly demonstrated only in 46% of all patients. Moreover, the sensitivity for direct visualization of thromboemboli at any specific location was only 26% (6). Therefore, the use of intraoperative TEE to diagnose acute PE via direct visualization may be limited and failure of TEE to directly visualize a PE within the pulmonary artery should not prevent a patient from undergoing further diagnostic testing or therapeutic intervention when a PE is suspected. In contrast, TEE may be of much greater value for identifying extrapulmonary thromboemboli within the caval veins, right atrium or right ventricle, as presented in this case report. Direct visualization of thromboemboli within the above locations is not only supportive of a diagnosis of PE, but is also critically important for patients who undergo pulmonary embolectomy, as it changes the surgical approach and technique. For example, we recently reported that intraoperative TEE identified intrathoracic, extrapulmonary thromboemboli in 26% of patients undergoing pulmonary embolectomy (n = 50), resulting in an alteration of surgical management in over 10% of patients (7). These findings support the critical role of intraoperative echocardiography during pulmonary embolectomy. In conclusion, we agree with the authors that TEE should be considered as a primary diagnostic tool and intraoperative monitor in the setting of acute perioperative cardiovascular collapse and suspected PE. However, failure of TEE to directly visualize a PE should not preclude a high-risk patient from undergoing further diagnostic evaluation or receiving a definitive treatment. Peter Rosenberger, MD Stanton K. Shernan, MD Department of Anesthesiology Perioperative and Pain Medicine Harvard Medical School Brigham and Women’s Hospital Boston, MA Thomas Weissmüller, MD Holger K. Eltzschig, MD Department of Anesthesiology and Intensive Care Medicine University Hospital Tübingen, Germany [email protected]