Echocardiographic reference intervals for right ventricular indices, including 3-dimensional volume and 2-dimensional strain measurements in healthy dogs.

Abstract

BACKGROUND: There is currently a lack of reference intervals (RIs) for the novel measures like 3-dimensional (3D) echocardiography or speckle-tracking strain for assessment of right ventricular (RV) structure and function. OBJECTIVES: To generate RIs and to determine the influence of age, heart rate, and body weight (BW) on various RV function indices using a dedicated RV software for 3D RV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), global and free wall RV longitudinal strain (RVLS), end-diastolic area (RVEDA), end-systolic area (RVESA), fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), and tissue Doppler imaging (TVI)-derived systolic myocardial velocity of the lateral tricuspid annulus (S'). ANIMALS: Healthy adult client-owned dogs (n&#xa0;=&#xa0;211) of various breeds and ages. METHODS: Prospective study. Reference intervals were estimated as statistical prediction intervals using allometric scaling for BW-dependent variables. Right-sided (upper limit) or left-sided (lower limit) 95%&#xa0;RIs were calculated for every variable. Inter- and intraobserver variability was determined. RESULTS: Most variables showed clinically acceptable repeatability with coefficient of variation less than 10. Upper or respectively lower RI after allometric scaling to normalize for different BWs were: EDVn&#x2009;&#x2264;&#x2009;2.5&#xa0;mL/kg, ESVn&#x2009;&#x2264;&#x2009;1.2&#xa0;mL/kg, TAPSEn&#x2009;&#x2265;&#x2009;4.5&#x2009;mm, RVEDAn&#x2009;&#x2264;&#x2009;1.4&#xa0;cm/kg, RVESAn&#x2009;&#x2264;&#x2009;0.8&#xa0;cm/kg, and TVI&#x2009;S'n&#x2009;&#x2265;&#x2009;5.6&#xa0;cm/s/kg. The calculated limits for indices without allometric normalization were: EF&#x2009;>&#x2009;42.1%, FAC&#x2009;>&#x2009;30.0%, free wall RVLS&#x2009;<&#x2009;-20.8%, and global RVLS&#x2009;<&#x2009;-18.3%. CONCLUSIONS: Echocardiographic RIs for RV structure and function are provided.