Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp dvances in congenital heart procedures, both surgical and interventional, have increased the life expectancy of patients with complex congenital heart disease (CHD). 1 This holds especially true for patients with single right ventricle (RV) physiology. A major medical issue that these patients are experiencing with increasing life expectancy after surgical palliation is progressive heart failure, with a reported incidence as high as 40%. 2,3 Adult guidelines for treatment of heart failure are mainly based on level A evidence; 4-6 however, most guidelines for pediatric/congenital heart failure treatment are based on, at best, level B evidence and more often level C evidence, the latter being the only evidence supporting heart failure treatment guidelines in patients with single-ventricle physiology. 7, 8 Multiple reasons exist for the lack of evidence for heart failure treatment in this complex population, but a definite reason is the inability to accurately and precisely assess RV function. The RV is difficult to image echocardiographically because of its anterior position in the chest, its course muscular trabeculations making chamber margins difficult to ascertain, and its relatively thin wall. 9 Because of these difficulties, cardiac magnetic resonance imaging (cMRI) is considered the gold standard for non-invasively evaluating RV function. However, because of practical considerations, echocardiography still remains the most often used modality for evaluating the RV. Current advances in echocardiographic techniques have been able to overcome some of the previous limitations in evaluating the RV and correlations with cMRI have been documented. 10-13 In addition, recent echocardiographic guidelines for evaluating the RV have been published to aid in standardizing practice in both pediatric and adult populations. 14, 15 In this review, we briefly discuss the characteristics of the RV and how this may differ in a single RV vs. a biventricular physiology. We also review the current available literature on the echocardiographic assessment of patients with single RV physiology using newer echocardiographic techniques.
RV's CharacteristicsThe RV differs embryologically, structurally, and functionally from the left ventricle (LV). These differences are likely related to both genetic/gene expression and physiology, and the interactions between them. These interactions have been described in the "normal" RV in a biventricular physiology, but significantly less is known about how a "normal" RV should develop in a single-ventricle physiology.The heart forms from a single tube after fusion of the bilateral heart fields. This tube consists essentially of the inflow and outflow limbs. The RV, conus, and truncus comprise the outflow limb. 16 Embryologically, the RV develops from cells that originate in the secondary heart field, whereas the LV Right ventricular (RV) function is increasingly recognized as having prognostic signifi...