The peak early velocities (E'), late diastolic velocities (A'), E'/A' ratio, isovolumetric relaxation
time (IVRT), S'-wave velocities, and myocardial performance index (MPI) were recorded.
Using conventional TTE, the mean values of the mitral and tricuspid early diastolic E wave, late diastolic A wave, isovolumetric relaxation
times (IVRT), deceleration time (DT) and E/A ratio were calculated from three cycles obtained with Doppler and evaluated according to the American Echocardiography Association guidelines (9).
In the evaluation of diastolic function, a significant increase in the isovolumetric relaxation
time after anesthetic induction, was observed in dogs receiving ketamine and diazepam (Table 3), which according to LESTER et al.
In the present study, the isovolumetric relaxation
time (IVRT) showed mean and SD of 102 [+ or -] 20.14 as compared to IVRT mean of Poirie et al  (2003) and Boyer et al  (2004) showing 109.11 msec and 79.14 msec respectively, which is statistically significant.
Subclinical hypothyroidism increases isovolumetric relaxation
time, decreases endothelial relaxation, and decreases cardiac contractility .
Reduced systolic and diastolic functions with an ejection fraction of 51% and delayed isovolumetric relaxation
time (IVRT) of 102 ms were determined, respectively.
Diastolic performance was evaluated using the mitral diastolic flow pattern parameters (E and A waves [early and late diastolic peak filling velocities]), E/A waves' ratio, mitral E wave deceleration time (EDT), isovolumetric relaxation
time (IVRT) , and tissue Doppler at the mitral annulus (septal and lateral).
The recordings across the MV orifice cAVC and developing were also used to evaluate the embryonic heart rate (HR) in beats per minute (BPM), cardiac cycle length (RR interval), diastolic ventricular filling time (DFT; 12.5 dpc, n = 11,14.5 dpc, n = 17, and 17.5 dpc, n = 16), ejection time (ET; 12.5 dpc, n = 11, 14.5 dpc, n = 17, and 175 dpc, n = 16), isovolumetric contraction time (IVCT; 12.5 dpc, n = 7,14.5 dpc, n = 17, and 17.5 dpc, n = 16), and isovolumetric relaxation
time (IVRT; 12.5 dpc, n = 7,14.5 dpc, n = 17, and 175 dpc, n = 16) of the LV (Figure 1(a)).
Diastolic function was also evaluated by means of absolute LV isovolumetric relaxation
time (IVRT), the ratio of maximal early diastolic peak velocity (E), and late peak velocity (A) of mitral flow (E/A ratio).
The LV diastolic function has been evaluated using the Pulse Wave (PW) Doppler transmitral flow applied in a 4-chamber apical view where the E and A wave velocities, E/A ratio, deceleration time (DT) and isovolumetric relaxation
time (IVRT) were calculated.
The interval 'a' from cessation to onset tricuspid valve inflow is equal to the sum of isovolumetric contraction time (ICT), ejection time, and isovolumetric relaxation
PW-DTI was performed in apical 4 and 2 chamber views; the Doppler sample volume was placed at four different sites of the mitral annulus and major velocity time intervals recorded- IVCT (isovolumetric contraction time), IVRT (isovolumetric relaxation
time) and S wave duration (ejection time).