Assessment of Right Ventricular Structure and Function

Introduction

The assessment of right ventricular (RV) structure and function is one of the most critical roles of echocardiography, often impacting the diagnosis, management, and prognosis of patients with suspected cardiovascular disease. Historically, the echocardiographic assessment of diseases affecting the RV has lagged behind that of the left ventricle, despite knowledge demonstrating that diseases affecting the right heart have been shown to have the same clinical consequences of those affecting the left heart. More recently, the assessment of RV structure and function has been an active area of investigation. The geometry of the RV is very complex, even in normal subjects, and even more complex in diseased states, which makes it especially difficult to assess with two-dimensional (2D) echocardiographic techniques. The RV myocardium is thin-walled and has a circumferential arrangement of myofibers in the subepicardium and longitudinal fibers in the endocardium ( Fig. 16.1 ). It assumes a flattened pear-shaped appearance folded over the left ventricle and consists of three components: (1) an inlet portion consisting of the tricuspid valve, chordae tendineae, and papillary muscles; (2) a trabecular apical myocardium; and (3) an infundibulum or conus, which encompasses the smooth walled RV outflow tract beneath the pulmonic valve ( Fig. 16.2 ). The need for careful and comprehensive echocardiographic evaluation of RV systolic function occurs in multiple clinical settings, including suspected RV cardiomyopathy, inferior wall myocardial infarction, atrial and ventricular septal defects, complex congenital heart disease, as well as valvular heart disease. Systolic dysfunction of the RV is also frequently observed in acute pulmonary embolism, pulmonary hypertension, and arrhythmogenic right ventricular dysplasia (ARVD), as well as in intraoperative settings. Despite the obvious need for accurate quantitative information, the assessment of RV systolic function is frequently more difficult to obtain due to the irregular crescent shape of this chamber, making quantitative assessment based on geometric remodeling especially challenging, although newer technologies have attempted to overcome these challenges.

Clinical Assessment of Right Ventricular Anatomy and Function

Today, in the majority of clinical settings, the assessment of RV anatomy and systolic function by echocardiography is still most often performed qualitatively with 2D techniques and relies on the scanning ability of the sonographer and trained interpretive eye of the echocardiographer. There is, however, increasing demand for more quantitative assessments of RV structure and function, and newer technologies, including RV strain and three-dimensional (3D) imaging of the right ventricle, have made the quantitative assessment of RV structure and systolic function more efficient, easy to obtain, and reproducible.

The ability to accurately assess global and regional RV systolic function with echocardiography requires continuous practice and attention to detail, with frequent correlation of coronary anatomy, other imaging tests, and pathologic findings. Knowledge of coronary flow to the RV and the use of multiple echocardiographic views to ensure that the entire RV is visualized are essential.

It is especially important to recognize that RV systolic dysfunction may be regional in the setting of coronary artery disease as well as other clinical scenarios, such as pulmonary embolism. Standard transthoracic apical views tend to optimize visualization of the left ventricle, and the transducer may need to be moved more laterally to optimize visualization of the RV. Since the RV myocardium is thin, measurement of wall thickening is usually not practical, and endocardial excursion alone must be evaluated. The interventricular septum is also frequently flattened in the setting of RV systolic dysfunction, and this creates challenges to the accurate assessment of systolic function. Despite these challenges, a complete evaluation of the RV should be a routine part of every comprehensive echo study, and with practice, overall accuracy will improve.