Right Atrial Anatomy

Right Atrium and SVC/IVC OutlineRight Atrial AnatomyRight Atrial EmbryologyRight Atrial FunctionNormal and Abnormal Flow PatternsRight Atrial and Right Atrial Appendage 2D ViewsSVC, IVC, CS Views2D Evaluation of Right Atrium2D Evaluation of Interatrial Septum2D Evaluation of SVC,IVC,CSDoppler Evaluation of Right Atrium - Part 1Doppler Evaluation of Right Atrium - Part 2Doppler Evaluation of Right Atrium - Part 3CME and Self Assessment Exams

Objectives

At the completion of this chapter the user should be able to:

Understand normal right atrium, vena cava, coronary sinus and IAS anatomy
Obtain TEE views of right atrium, vena cava, coronary sinus and IAS and hepatic vein anatomy
Identify normal and abnormal right atrium, vena cava, coronary sinus and IAS structures
Evaluate PWD of right atrium, vena cava, coronary sinus and IAS, Hepatic vein
Obtain quantitative Doppler measurements for right atrium, vena cava, coronary sinus, hepatic vein

Anatomy

The right atrium is an ovoid structure with slightly thinner walls than the left atrium. The right atrial appendage is anterior to the right atrium. The right atrial appendage and the right atrial walls contain pectinate muscles which may appear as small ridges on an echocardiography exam. The left border is the interatrial septum and the right border is the free wall which is parallel to the right side of the sternum. There are 4 openings of the right atrium:

(1) The Superior Vena Cava (SVC)
(2) The Inferior Vena Cava (IVC)
(3) The Coronary Sinus (CS)
(4) The Tricuspid Valve (TV)

The superior vena cava (SVC) empties into the right anterior portion of the superior wall of the right atrium. The inferior vena cava (IVC) empties into the right posterior margin of the inferior wall of the right atrium. The coronary sinus empties into the infero-posterior portion of the right atrium. The coronary sinus is posterior to the inferior border of the interatrial septum and superior to the posterior portion of the tricuspid valve annulus. The right atrium receives blood from the SVC, IVC, and coronary sinus. Blood exits the right atrium via the tricuspid valve.

Right Atrial Anatomy


Superior Vena Cava - Short Axis	Superior Vena Cava - Short Axis


Superior Vena Cava - Long Axis	Superior Vena Cava Long Axis


Inferior Vena Cava - ME 4CV	Inferior Vena Cava - ME 4CV


Inferior Vena Cava - BCV	Inferior Vena Cava - BCV


Coronary Sinus - BCV	Coronary Sinus - BCV


Coronary Sinus/Tricuspid Valve	Coronary Sinus/Tricuspid Valve

The interatrial septum is a thin muscular membrane that separates the right and left atrial chambers. An oval indentation is in the middle of the septum, the fossa ovalis, corresponds to the foramen ovale in the fetal heart. The coronary sinus may contain a valve, the thesbian valve. The superior vena cava has a ridge called the crista terminalis. The inferior vena cava usually has a fetal remnant of a valve called the eustachian valve. A filamentous collection attached to the inferior vena cava and sometimes extending to the foramen ovale is called a chiari network. The chiari network , found in about 2% of patients, is a congenital remnant of the right valve of the sinus venosus and is associated with a patent foramen ovale or an interatrial septal aneurysm.

RIght Atrial Anatomy


Chiari Network	Chiari Network


Interatrial Septum	Interatrial Septum


Eustachian Valve	Eustachian Valve


Crista Terminalis	Crista Terminalis

Normally, the right atrium is smaller than the left atrium. A right atrium of equal size or larger than the left atrium is interpreted as right atrial enlargement. The superior vena cava is usually a small vessel, usually less than 2 cm in diameter. The inferior vena cava's width depends upon the volume status and the respiration status of the patient.