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Direct visualization of the left atrial appendage using esophageal radial endoscopic ultrasound: An alternative to TEE

Published:August 15, 2013DOI:https://doi.org/10.1016/j.hrthm.2013.08.013
      Preprocedural transesophageal echocardiography (TEE) to exclude left atrial appendage (LAA) thrombus before cardioversion or left atrial catheter ablation is routinely performed to lower the incidence of periprocedural strokes. Conventional TEE was attempted in a 64-year-old man with atrial flutter of unknown duration. He had two unsuccessful attempts at blind esophageal intubation with the TEE probe by two separate operators, both under conscious sedation and under moderate anesthesia. Gastroenterology was consulted for evaluation of the hypopharynx and esophagus via endoscopy. Use of endoscopic ultrasound (EUS) was suggested to directly visualize the hypopharynx, avoiding blind intubation and facilitating passage of the probe. Once positioned in the esophagus, the ultrasound feature of the EUS then would be used to survey the LAA before cardioversion. The procedure was performed using a Pentax Radial Array Echoendoscope (EG-3670URK, Pentax Medical, Montvale, NJ). This endoscope features a 360° radial-array ultrasound transducer, which generates a high-resolution image while providing forward-viewing video. The EUS identified redundant supraglottic tissues in our patient, likely responsible for the difficult initial blind intubation with the TEE probe. Once the EUS probe was passed into the esophagus, the ultrasound images obtained allowed complete visualization of the LAA body and pectinate muscles, effectively ruling out thrombus (Figure 1). The LAA was also interrogated with pulsed-wave (PW) Doppler, and emptying velocities (cm/s) within the LAA were recorded (Figure 2). Commercially available equipment for TEE offers a multiplane phased-array transducer and requires standard blind esophageal intubation under conscious sedation or anesthesia. Occasionally, blind esophageal intubation may be difficult or impossible to perform due to functional or anatomic variations in the hypopharynx/upper esophagus. A study of 10,000 TEEs found that the probe could not be passed because of lack of patient cooperation and/or operator experience in 2% of patients, and the probe had to be removed prematurely in 0.5% because of patient intolerance.
      • Daniel W.G.
      • Erbel R.
      • Kasper W.
      • et al.
      Safety of transesophageal echocardiography: a multicenter survey of 10,419 examinations.
      The inability to pass the TEE probe usually results in procedural delays, procedure cancellations, or unnecessary prolonged exposure to anticoagulation. Blind difficult esophageal intubations may cause trauma to the hypopharynx, resulting in both patient discomfort and, rarely, traumatic perforation.
      • Min J.K.
      • Spencer K.T.
      • Furlong K.T.
      • et al.
      Clinical features of complications from transesophageal echocardiography: a single-center case series of 10,000 consecutive examinations.
      Direct visualization of the hypopharynx with forward-video EUS is likely to avoid trauma and complications. For this reason, EUS is an attractive alternative to TEE, especially because the ultrasound information needed to rule out LAA thrombus is provided by the same endoscope. To date, there is no comparable alternative to a TEE that allows for visualization of the entire LAA to reliably rule out thrombus. Alternatives such as multidetector computed tomography,
      • Jaber W.A.
      • White R.D.
      • Kuzmiak S.A.
      • et al.
      Comparison of ability to identify left atrial thrombus by three-dimensional tomography versus transesophageal echocardiography in patients with atrial fibrillation.
      cardiac magnetic resonance imaging,
      • Rathi V.K.
      • Reddy S.T.
      • Anreddy S.
      • et al.
      Contrast-enhanced CMR is equally effective as TEE in the evaluation of left atrial appendage thrombus in patients with atrial fibrillation undergoing pulmonary vein isolation procedure.
      and intracardiac echocardiography
      • Saksena S.
      • Sra J.
      • Jordaens L.
      • et al.
      A prospective comparison of cardiac imaging using intracardiac echocardiography with transesophageal echocardiography in patients with atrial fibrillation: the intracardiac echocardiography guided cardioversion helps interventional procedures study.
      are promising, but TEE remains the gold standard modality recommended by the ACC/AHA/HRS for this purpose. This echoendoscope is capable of 5-, 7.5-, and 10-MHz ultrasound frequencies. PW Doppler interrogation also is available, which allows measurements of LAA emptying velocities. This modality potentially can be used to interrogate the LAA and exclude thrombus when TEE is difficult to perform in patients with complicated pharyngeal–esophageal anatomy. Potential limitations include the lack of multiplanar imaging angles and, with it, the possibility of missing a small thrombus, the need for coordination between cardiology and a gastroenterologist trained in EUS, and, possibly, issues with reimbursement for the operators.

      Abbreviations:

      EUS (endoscopic ultrasound), LAA (left atrial appendage), LSPV (left superior pulmonary vein), PW (pulsed wave), TEE (transesophageal echocardiography)

      Keywords

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