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 statistical calculation of standard deviation, expert opinion, and assessment of associated outcome. It is recommended that the same values be used to assess RV size for both transesophageal (TEE) and transthoracic echocardiography (TTE), even though the actual images obtained may be markedly different.7 Quantification with TEE is frequently very challenging due to the increased difficulty in achieving standard image planes and views.

Midesophageal Views

Probably the most useful view for RV assessment is the midesophageal four-chamber (ME-4C) view. To image the right ventricle, the standard ME-4C view is obtained and the probe is then turned slightly to the right to bring the tricuspid valve into the middle of the screen (Figure 13–1). The basilar RV free wall will be to the left of the screen while the apical portion of the free wall will be in the far field or slightly to the right, depending on the orientation of the heart. It may be useful to increase the multiplane angle to 10° to 20° to optimize the view of the RV cavity. A normal RV will be no more than two-thirds the longitudinal extent of the LV with the LV comprising the apex of the heart. From this imaging plane, the mid-cavity and longitudinal diameters of the RV may be measured and systolic motion qualitatively assessed (Figure 13–2). In addition, color-flow (CFD) and spectral Doppler analysis of trans-tricuspid flow as well as tissue Doppler examination of the tricuspid annulus may be performed from this image to evaluate possible valvular pathology and diastolic dysfunction. The ME-4C view is also an excellent view in which to quantify the right atrium (RA) by measuring its major and minor axes and comparing it to its partner to the left. As opposed to the left atrium (LA), normal ranges for RA size are not different for men and women. Normal reference limits for RV and RA size as well as partition values for mild, moderate, and severe enlargement are listed in Table 13–1.7

Rotation of the TEE multiplane angle to approximately 30° to 60° and slight rotation of the probe to the right will bring the inflow-outflow or wrap-around view onto the screen (Figure 13–3). In this view, the RA, tricuspid valve (TV), RV, pulmonic valve (PV), and proximal pulmonary artery (PA) appear in order from the left side of the screen in an arc sweeping counter-clockwise in the far field around the aortic valve to the right. The RV inferior or diaphragmatic free wall is visible in the far field and the infundibular portion of the RV is particularly well seen closer to the right side of the screen. This is also an excellent view in which to use CFD to interrogate the TV and PV and to measure the dimensions of the PV annulus as well as the RV outflow tract (RVOT) or the immediate subpulmonary regions (Figure 13–4; see Table 13–1).

Further rotation of the multiplane angle to 90° to 120° while keeping the RA in view will bring the bicaval view onto the screen with the left atrium in the near field, the superior vena cava to the right, and the inferior vena cava (IVC) to the left (Figure 13–5). Frequently, the eustachian valve is seen emanating from the junction of the RA with the IVC at the lower end of the crista terminalis. This fetal remnant may have a mobile, filamentous structure associated with it that is known as a Chiari network, and is considered a normal variant (see Chapter 3). The interatrial septum is visible in the center of the screen and may be easily examined for a patent foramen ovale or other abnormalities. The tricuspid valve may be brought into this image at the far left field by further multiplane transducer angle rotation. This modified bicaval view is ideal for spectral Doppler analysis of a tricuspid regurgitation jet as the direction of the jet is usually closely aligned with the direction of the ultrasound beam (Figure 13–6). The coronary sinus is often seen just underneath the IVC to the left side of the screen and may prove useful in placement of a coronary sinus catheter during cardiac surgery (see Chapter 5).

Transgastric Images

Transgastric images of the RV should be carefully examined as it is not uncommon that some of the best images of the RV are obtained from this position. A transgastric short-axis (TG-SAX) view of the RV is obtained by advancing the TEE probe into the stomach (35 to 45 cm from the incisors), flexing the probe, identifying the LV, and turning the probe to the patient’s right. The RV will appear crescent shaped and wrapped around the LV. The tricuspid leaflets are often seen in short axis with extreme flexion (Figure 13–7). A long-axis or inflow RV view may be obtained one of two ways. From the LV short-axis view, the probe is turned to the right to bring the RV short-axis view into the center of the screen and the multiplane angle is rotated to 90° to 140°, yielding a view with the RV to the left of the screen, the TV in the middle, and the RA to the right (Figure 13–8A). The inferior free wall will appear in the near field and the anterior free wall in the far field. Alternatively, from the LV short-axis view, the transducer angle is advanced to 100° to 120°, identifying the LV long-axis view, and the probe is then turned to the right to reveal the RV inflow or long-axis view. Spectral Doppler analysis is not optimal from this position given the divergence between the angle of the ultrasound beam and the direction of blood flow (Figure 13–8B).

An RV outflow view may occasionally be developed from the RV short-axis view by rotating the multiplane angle slowly towards 100° to 130°, but also turning the probe slightly towards the patient’s left (Figure 13–9A). The RVOT and PV will appear in the mid–far field, parallel to the beam, often in optimal position for color and spectral Doppler analysis, should that be desired (Figure 13–9B).

The deep transgastric image of right-sided structures is sometimes optimal for assessment of tricuspid annular motion with tissue Doppler methods.8 This image is obtained by advancing the probe to the deep transgastric position, flexing the tip to identify the deep transgastric images of the LV, and turning the probe slightly towards the patient’s right side (Figure 13–10). The result often resembles an apical four-chamber image obtained with transthoracic echocardiography.

The transgastric position is also the appropriate position from which to examine hepatic vein flow (Figure 13–11). From the transgastric position, the probe is turned to the patient’s right side until the liver is seen. An appropriately sized and positioned vein is chosen and the multiplane angle is rotated such that the vein is as linear and as parallel with the ultrasound beam as possible. Spectral Doppler analysis of flow is then performed to examine flow patterns, in a manner analogous to that of pulmonary venous flow.

Exposure to chronic conditions of excessively high preload or afterload will eventually result in fundamental changes to the structure of the RV. However, the mechanisms by which the RV copes with pathologic changes depends on whether it is facing increases in pressure work or increases in volume work.