Right Atrium Anatomic Pitfalls - Part 1

Artifacts and Pitfalls OutlineCardiac EmbryologyRight Atrium Anatomic Pitfalls - Part 1Right Atrium Anatomic Pitfalls - Part 2Right Atrium Anatomic Pitfalls - Part 3Right Ventricular PitfallsLeft Atrium PitfallsLeft Ventricular PitfallsAortic Valvular PitfallsOther Anatomic PitfallsArtifacts - Part 1Artifacts - Part 2Artifacts - Part 3Artifacts - Part 4SummaryCME and Self Assessment Exams

Anatomic Pitfalls by Cardiac Chamber

Right Atrium

The crista terminalis is a muscle ridge seen anteriorly in the midesophageal (ME) bicaval view at the junction of the SVC and the right atrium. However anatomically it lies between the SVC and IVC. On TEE, it may appear to protrude into the right atrium and be mistaken for thrombus or tumor.

Crista Terminalis


Crista Terminalis	Crista Terminalis
ME BCV	ME SVC LAX View

The eustachian valve can be seen in the ME 4-chamber view or the ME bicaval view of the right atrium; it is seen in approximately 25 - 50% individuals, at the junction of the inferior vena cava (IVC) and right atrium. It appears as an elongated, membranous, possibly undulating structure, with a varying width. It may appear to attach to the fossa ovalis but does not cross the tricuspid valve or right ventricle. It can be confused with the tricuspid valve in a ME 4 chamber view, although it is located superior to the tricuspid valve. Usually it is of no physiological consequence, but can be confused with an intracardiac thrombus, cause turbulent atrial blood flow, complicate IVC cannulation or serve as a site for endocarditis formation. However, at least one study has associated a persistent eustachian valve with a patent foramen ovale, with the attendant increased risk of paradoxical emboli.

In a ME 4-chamber view, with slight probe advancement, the coronary sinus is seen in a longitudinal axis as an echo-free space just superior to the tricuspid valve in the right atrium. The coronary sinus can also be seen in the ME 2-chamber view as small echo-free circles in the AV groove on either side of the left atrium or in the bicaval view as a curvilinear structure at the left border of the left atrium. Dilation of the coronary sinus to greater than 1 cm suggests a persistent left superior vena cava, or right sided volume/pressure overload. When present, a persistent left superior vena cava will drain into the coronary sinus along the atrioventricular groove. An agitated saline injection into a left upper extremity vein which opacifies the coronary sinus and then the right atrium will confirm the diagnosis.


Left Persistent Superior Vena Cava	Left Persistent Superior Vena Cava

The thebesian valve may be seen as a thin piece of tissue guarding the entrance to the coronary sinus in the ME 4 chamber midesophageal view (slightly pushed in to visualize the coronary sinus) or the ME bicaval view. It may inhibit cannulation of the coronary sinus for retrograde cardioplegia or biventricular pacing lead placement.


	Pectinate Muscles

The chiari network is a very mobile, filamentous, thin and possibly perforated structure commonly seen within the right atrium. It is probably a remnant of sinus venosus derived structures, but has also been called a 'fenestrated eustachian valve'. The chiari network moves about the right atrium with a random movement, not necessarily related to valvular movement. It may impede catheters placement through the right atrium for femoral venous drainage or retrograde cardioplegia. Chiari networks have been associated with a patent foramen ovale, paradoxical embolus and an interatrial septal aneurysm.


	Chiari Network