Introduction and objectives: The velocity-time integral (VTI) and the mean velocity of valvular flow are widely-used variables in Doppler-echocardiography. The aim of the present work was to determine normal VTI and mean velocity values of valvular flow and their relation to age, sex, heart rate and body surface area.
Methods: One hundred and fifty-six patients (84 men, 72 women; age range: 6-86 y; mean: 37 +/- 20) without cardiovascular disease were studied by Doppler echocardiography. VTI and the mean velocity of left and right ventricular outflow tract, and mitral and tricuspid valvular flow were determined by pulsed-wave Doppler. Aortic and pulmonary valvular flow were assessed by continuous wave Doppler.
Results: Mean value of aortic valvular flow VTI (22 +/- 4 cm) was slightly higher than that of pulmonary valvular flow (20 +/- 4 cm). Mean VTI values of left and right ventricular outflow tract and mitral valvular flow were similar (16 +/- 3, 15 +/- 3 and 15 +/- 3 cm, respectively) with an acceptable correlation (r = 0.76-0.83). VTI of tricuspid valvular flow was clearly lower than the rest (10 +/- 3 cm; p < 0.001). Linear regression analysis showed the VTI to be inversely related to heart rate and age, and mean velocity positively related to heart rate and inversely to age. While VTI remained relatively stable up to the age of 60 and decreased sharply thereafter, mean velocity decreased progressively with age. VTI values were identical for both sexes; however, mean velocity was higher in women up to the age of 60.
Conclusions: VTI is a Doppler parameter independent of body surface area, inversely related to heart rate, not sex-related and remains stable up to the age of 60. Normal mean velocity values should be defined in relation to heart rate and age. Normal values of these Doppler parameters should be borne in mind for non-invasive assessment of cardiovascular function.