Effects of age, body weight, and heart rate on transmitral and pulmonary venous flow in clinically normal dogs

Objective-To determine the influence of age, body weight (BW), heart rate ( HR), sex, and left ventricular shortening fraction (LVSF) on transmitral an d pulmonary venous flow In clinically normal dogs. Animals-92 client-owned dogs 3 months to 19 years old. Procedure-Transthoracic Doppler echocardiography recordings of transmitral flow and pulmonary venous flow were obtained in conscious unsedated dogs. I nfluence of age, BW, HR, sex, and LVSF on diastolic variables was assessed, using statistical methods such as ANOVA on ranks and univariate and multiv ariate forward stepwise linear regression analyses. Results-Age significantly influenced isovolumic relaxation time (IVRT, r=0. 56), ratio between peak velocity of the early diastolic mitral flow wave-to -peak velocity of late diastolic mitral flow wave (E:A; r = -0.44), deceler ation time of early diastolic mitral flow (DTE; r =0.26), and peak velocity of atrial reversal pulmonary venous flow wave (AR-wave; r=0.37). Significa nt changes of mitral inflow and pulmonary venous flow variables were eviden t only in dogs >6 and >10 years old, respectively, Body weight significantl y Influenced DTE (r=0.63), late diastolic flow duration (r=0.60), and AR du ration (r=0.47), whereas HR significantly affected DTE (r=-0.34), IVRT (r = -0.33), and peak velocity of AR (r=0.24). Sex or LVSF (range 22 to 48%) di d not influence any echocardiographic variables. Conclusions and Clinical Relevance-Age, BW, and HR are important factors th at affect filling of the left atrium and left ventricle In clinically norma l dogs.