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 = 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% 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 ≤ 2.5 mL/kg(0.942) , ESVn ≤ 1.2 mL/kg(0.962) , TAPSEn ≥ 4.5 mm(0.285) , RVEDAn ≤ 1.4 cm(2) /kg(0.665) , RVESAn ≤ 0.8 cm(2) /kg(0.695) , and TVI S'n ≥ 5.6 cm/s/kg(0.186) . The calculated limits for indices without allometric normalization were: EF > 42.1%, FAC > 30.0%, free wall RVLS < -20.8%, and global RVLS < -18.3%. CONCLUSIONS: Echocardiographic RIs for RV structure and function are provided.