As the role of the right ventricle (RV) in overall cardiac function has been more fully appreciated, greater efforts have been made to describe and quantify RV function using TEE in ways useful to clinicians. These efforts have been frustrated by the non-geometric, asymmetric shape of the chamber, its sequential contraction pattern, and the obscuring effect of epicardial fat on RV wall motion and thickness. In addition, the RV is exquisitely sensitive to loading conditions, overall pulmonary function, and the interdependence of the two ventricles.
The RV is anatomically divided into its inflow and outflow portions reflecting its dual embryonic origin. The inflow portion begins at the tricuspid valve and extends towards the apex to include the trabeculated, posteroinferior segments, while the outflow portion is usually free of trabeculations and includes the infundibulum (anterosuperior segments) and pulmonic valve. A series of muscular bands divide the two portions, the most important to the echocardiographer being the moderator band. This structure extends from the base of the anterior papillary muscle to the ventricular septum and should not be mistaken for a thrombus or intracavitary mass (see Chapter 3).1,2
Ventricular systolic ejection of the RV has a different pattern than that of the left ventricle. The ejection phase begins earlier and lasts longer, while the velocity profile is characterized by a lower and delayed peak.3 Right ventricular ejection is largely due to a bellows-like motion of the free wall and longitudinal shortening of the ventricle (apex to annulus) rather than the twisting and rotational motions that predominate on the left side.2,4 Finally, contraction of the RV is sequential, beginning with the free wall and moving towards the infundibulum.5
Although the vast majority of information about the RV can be obtained from a small number of images, the chamber's complexity defies standardized description or definition. The RV is a paradoxical structure, appearing triangular in one view but of an elongated, crescent shape in another. Likewise, while it usually appears smaller than the left ventricle (LV), its end-diastolic volume is actually greater.2
As the RV cannot be completely seen in any single image, multiple scan planes are required to adequately assess RV structure and function. The RV has approximately one-sixth the mass of the LV, and performs about one-quarter of its partner's stroke work.6 It consists of a free wall, an inferior or diaphragmatic wall, a septal wall, and an outflow tract (RVOT) region, although there is no formal segmental scheme for classifying wall motion as exists for the LV.
Despite this, a series of guidelines have been developed that attempt to establish standards for measurement of global RV size and function. Most important of these are the Recommendations for Chamber Quantification, developed jointly by the American Society of Echocardiography and the European Association of Echocardiography.7 These standards were developed by a combination of methods, including ...