Functional Separation Of The Right Atrium By An Elongated Eustachian Valve

A 78-yr-old man with coronary artery disease, moderate aortic stenosis, obstructive sleep apnea, and pulmonary hypertension (pulmonary artery pressure 40/25 mm Hg) presented for revision of a total knee arthroplasty. After placement of a lumbar epidural catheter, general anesthesia was induced and a transesophageal echocardiography (TEE) probe was inserted to exclude a patent foramen ovale (PFO), which would increase the risk for paradoxical embolization, particularly in the setting of pulmonary hypertension. The TEE examination revealed normal biventricular systolic function, grade II left ventricular diastolic dysfunction (pseudo-normal transmitral inflow pattern on pulse wave Doppler and marked E’ reduction on mitral annulus tissue Doppler), estimated pulmonary artery systolic pressure of 48 mm Hg (using the peak velocity of tricuspid regurgitation jet) and an aortic valve area of 1.1 cm (using the continuity equation). In the midesophageal bicaval view, an echo dense, 28 mm long structure was noted, consistent with an elongated Eustachian valve (Fig. 1, upper panel). The tip of this valve was loosely suspended by a filamentous membrane adherent to the opposite atrial wall (Video Loop 1; please see video loops available at www.anesthesia-analgesia.org). After color flow Doppler imaging (using a Nyquist limit of 30 cm/s) of the interatrial septum failed to confirm a PFO, a bubble study was performed. Injection of agitated saline via an upper extremity vein suggested functional separation of the right atrium into upper (superior vena cava [SVC] tricuspid valve) and lower (inferior vena cava [IVC] intraatrial septum) compartments (Fig. 1, lower panel). Although there appeared to be IVC flow through the Eustachian valve towards the tricuspid valve, no contrast material entering the right atrium via the SVC was seen below the level of the Eustachian valve, suggesting a uni-directional valve mechanism (Video Loop 2; please see video loops available at www.anesthesia-analgesia.org). Using a modified midesophageal four chamber view (obtained by advancing the TEE probe with clockwise rotation), the proximity of the elongated Eustachian valve to the orifice of the coronary sinus was demonstrated (Fig. 2). The surgical procedure was uneventful without obvious embolization and the patient was discharged from the hospital on the fourth postoperative day. The prominent Eustachian valve is an embryologic remnant that derives from the sinus venosus. These remnants have different degrees of persistence after birth leading to a wide variability in the size of the Eustachian valve. Cor triatriatum dexter results when early embryologic separation of the right atrium into two chambers persists. (Fig. 3, left panel). A moderate degree of persistence can give rise to an elongated Eustachian valve with functional separation of inferior and SVC systems, as in this case (Fig. 3, middle panel). Lesser degrees of persistence may result in a Chiari network, a smaller Eustachian valve and also a crista terminalis, all of which are frequently seen on TEE examination. Lastly, the inferior portion of the sinus venosus persists as the thebesian valve, guarding the orifice of the coronary sinus (Fig. 3, right panel). Midesophageal TEE views are used to image structures derived from the sinus venosus. At 0 degrees with clockwise turn of the TEE probe, most of the right atrium is visualized (Fig. 1, upper panel). By slowly advancing the probe distally, the interatrial septum is imaged. When the floor of the right atrium is reached, the orifice of the coronary sinus is found, entering close to the septal leaflet of the tricuspid valve (Fig. 2). Mild retroflexion of the This article has supplementary material on the Web site: www.anesthesia-analgesia.org.