Transesophageal Echocardiography and Normal Variants

To the Editor: One of the major uses of echocardiography is detection of objects in and around the heart. With increasing intraoperative use of transesophageal echocardiography (TEE) by anesthesiologists, the potential exists that detection of an object that is in reality a rare, yet normal, variant may lead to unnecessary surgical intervention. Such a case is reported. The patient was a 68-yr-old Caucasian female scheduled for repeat coronary artery bypass grafting. After routine induction of anesthesia, a biplane TEE probe was uneventfully inserted. In the transverse view, an object was identified in the right atrium that seemed to represent the end of a "J" tip guide wire Figure 1. It was thought that the guide wire, in whole or in part, may have been inadvertently left in the patient during her previous coronary artery bypass grafting surgery. The guide wire from our right internal jugular vein catheterization had been removed intact. No chest radiographs were available at this time. The surgeon was notified and planned on opening the right atrium during the surgery to remove the guide wire. Although extended survival after central guide wire embolism has been reported [1], embolized fragments located in the central venous system or right heart should always be removed whenever reasonably possible because they are associated with approximately 71% morbidity and 38% mortality [2]. Mortality is highest when the guide wire is located in the right heart, lower when located in the vena cava, and lowest when located in the pulmonary artery [2]. However, further examination in the longitudinal view altered the appearance of the object Figure 2. In the longitudinal view, the object seemed to be attached to the right atrial wall and did not seem to be as characteristic of a "J" tip guide wire as seen in the transverse view. After further consultation with the surgeon, it was decided that this object was likely a eustachian valve (a rare, yet normal, variant), and opening the right atrium for exploration was not indicated. At the end of the procedure, the surgeon probed the right atrium with his finger after removal of the venous cannula and felt nothing abnormal. Postoperative chest radiographs were normal.Figure 1: Transverse view. Unmarked arrow points to object thought to represent the end of a "J" tip guide wire. IAS = interatrial septum; LA = left atrium; PAC = pulmonary artery catheter.Figure 2: Longitudinal view. Unmarked arrow points to eustachian valve. IAS = interatrial septum; LA = left atrium; PAC = pulmonary artery catheter.Two structures found rarely within the right atrium that may mimic pathology are the eustachian valve and the Chiari network [3]. The eustachian valve was initially described by Eustachius in 1563 and is located at the opening of the inferior vena cava into the right atrium [4]. Although of no functional significance in the adult, the eustachian valve functions in the fetus to direct blood flow preferentially from the inferior vena cava through the foramen ovale into the left atrium. A eustachian valve is found in up to 86% of autopsy examinations [5], yet it is visualized in only 0.20% of routine echocardiographic examinations as a mobile, curvilinear structure in the right atrial cavity [4]. It is not surprising, therefore, that a prominent eustachian valve may mimic pathology [6]. The Chiari network was initially described by Chiari in 1897 and consists of a network of fine or course fibers in the right atrium [5]. It represents the filamentous remnant of the valve of the coronary sinus, and its exact function is unknown. The Chiari network is found in only 2%-3% of autopsy examinations and is visualized in only 1.5% of routine echocardiographic examinations as a delicate, highly mobile, serpentine structure in the right atrial cavity [7]. With increasing use of TEE by anesthesiologists, the potential exists that detection of an object that is in reality a rare, yet normal, variant could lead to an unnecessary surgical intervention. This case emphasizes the importance of knowledge of normal variants and also emphasizes the importance of obtaining multiple echocardiographic views during TEE in order to increase diagnostic recognition of such variants. Mark A. Chaney, MD Department of Anesthesiology, Foster G. McGaw Hospital, Loyola University Medical Center, Maywood, IL 60153