We thank Drs. Tebbs and Lennon for emphasizing the role of epicardial echocardiography as a supplement to transesophageal echocardiography (TEE) to improve the sensitivity of ultrasound visualization of thromboemboli within the pulmonary artery (PA). Epicardial echocardiography is routinely used during cardiac surgery for scanning the ascending aorta prior to cannulation or cross-clamping, as it is more sensitive than TEE for detecting aortic plaques (1). In addition, epicardial echocardiography can be used as an alternate imaging modality for patients in whom TEE is contraindicated (2), or probe insertion cannot be achieved (3). Epicardial echocardiography is particularly useful for visualizing anterior structures of the heart, due to the proximity of the transducer to the cardiac surface and availability of transducers with high ultrasound frequencies, permitting superior resolution (4,5). Finally, left pulmonary artery visualization from an esophageal probe position is often limited due to interposition of the left mainstem bronchus (6). Thus, echocardiographic examination of the pulmonary artery using an epicardial approach may provide superior echocardiographic windows and imaging quality compared to TEE.
Although we agree with Drs. Tebbs and Lennon that in comparison to TEE epicardial echocardiography may be a superior technique for visualizing thromboemboli within the proximal pulmonary artery circulation, the sensitivity and specificity of epicardial echocardiography for this indication has not been thoroughly investigated (7). Furthermore, the epicardial echocardiographic approach to visualizing the heart and great vessels requires a sternotomy or thoracotomy, and therefore has practical limitations as a preoperative diagnostic modality. Finally, TEE may still be useful for imaging extrapulmonary thromboemboli in the right heart and caval veins in patients presenting for pulmonary embolectomy (8). Nonetheless, epicardial echocardiography should still be available to the perioperative echocardiographer as an essential diagnostic technique (9)
Peter Rosenberger, MD
Stanton K. Shernan, MD*
Simon C. Body, MB, ChB, MPH*
Holger K. Eltzschig, MD*†
*Department of Anesthesiology
Perioperative and Pain Medicine
Harvard Medical School
Brigham and Women’s Hospital
†Department of Anesthesiology and Intensive Care Medicine
Tübingen University Hospital
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