Right ventricular normal measurements: time to index?

Background: Despite the common practice of indexing left ventricular dimensions to body surface area, there remains a lack of indexed normal right ventricular (RV) two-dimensional caliper measurements. Variations in ranges for normal RV dimensions have been shown to exist, and indexing RV dimensions according to body surface area may help reduce this and provide a standardization useful for clinical practice. The aim of this study was to prospectively establish both absolute and indexed normal dimensions for the right ventricle using standardized positions in a multiethnic population. Furthermore, the effects of both gender and ethnicity on both the absolute and indexed results were also evaluated. Methods: Two hundred five healthy volunteers from four ethnic backgrounds (Indian, Chinese, Malay, and European) were prospectively enrolled and underwent two-dimensional echocardiography according to a set protocol. Ten measurements were made in conjunction with previous research. Intraobserver and interobserver and test-retest variability was assessed using coefficients of variation and intraclass correlation coefficients. Results: Male absolute results exceeded female absolute results in 90% of measurements (P = .003). European absolute results (male and female) were significantly larger in up to eight of 10 measurements (P = .01). When indexed, female results became significantly larger (P <.001) than male results. Indexing was able to reduce the number of statistical differences between male ethnic groups. Measurements showed good levels of intraobserver and interobserver variability for apical and short-axis measurements. Conclusions: Gender and body surface area play an important part in the determination of normal RV reference ranges, whereas ethnicity has little influence. Results using the suggested RV markers for these measurements showed good repeatability.