IVRT

(redirected from Isovolumic Relaxation Time)
AcronymDefinition
IVRTIsovolumic Relaxation Time
IVRTIn Vitro Release Test (drug performance test)
IVRTIntel Virus Response Team
References in periodicals archive ?
Three important echo parameters that had shown a stronger statistical correlation with exercise intolerance are non-shortening of isovolumic relaxation time, shortened deceleration time and continued E/A reversal.
Impaired left ventricular relaxation was suggested by significant prolonged E deceleration time and isovolumic relaxation time in WD-fed rats.
Importantly, ZO-Rap exhibited worsening of relative wall thickness, Vp, E/Vp, and isovolumic relaxation time at the end of treatment (12 weeks) compared to the middle of treatment (6 weeks) (Figures 2(b), 2(d), 2(e), and 2(f)) and compared to the untreated ZO-C.
MPI is calculated by dividing the sum of isovolumic contraction time (ICT) and isovolumic relaxation time (IRT ) by ejection time (ET ).
Pozzi et al found that in cirrhotic patients with tense ascites, the A wave velocity is markedly increased, the E/A ratio is markedly reduced and the deceleration time is significantly prolonged, whereas Wong et al reported prolonged isovolumic relaxation time in cirrhotic patients irrespective of the presence of ascites with significantly reduced E/A ratios only in ascitic subjects.
They found on Doppler derived indices of diastolic function, a significant prolongation of the isovolumic relaxation time (IVRT), increased A wave and reduced early diastolic mitral flow velocity/late diastolic mitral flow velocity ratio.
When individual time intervals which constitute MPI were analyzed, in normal persons LV isometric contraction time (ICT) was found to be 23.75 [+ or -] 6.26 msec; isovolumic relaxation time (IVRT) 72.83 [+ or -] 6.67 msec and LV ejection time 286.4 [+ or -] 29.26 msec.
After infusion, diastolic parameters like velocity of propagation (Vp) and isovolumic relaxation time (IVRT) improved almost to same extent in both groups but deceleration time (DT) did not.
The relevant echocardiographic parameters were measured in both subject groups: myocardial performance index (MPI), isovolumic relaxation time (IRT), isovolumic contraction time (ICT), pre-ejection period (PEP), ejection time (ET), PEP/ET ratio, deceleration time (DT) and acceleration time (AT).
where the P is the instant pressure during isovolumic relaxation phase, [P.sub.0] is the left ventricular pressure at any time before the time of left ventricular pressure of P, e is the base of natural logarithm, t is the time interval between the pressure of [P.sub.0] and P, [tau] is the isovolumic relaxation time constant.
Also, nonischemic cardiomyopathy patients with more than mild degree of mitral regurgitation versus those with mild regurgitation, not only demonstrate greater PMD but also have more advanced degrees of diastolic dysfunction (shorter deceleration time and isovolumic relaxation time) so teasing out the role of myocardial dysfunction versus timing of regional contraction will be important in further defining the mechanistic basis of mitral regurgitation.
Myocardial early (Em) and atrial (Am) peak velocities (cm/s), Em/Am ratio, and Sm-Em duration (isovolumic relaxation time: IVRTL) were measured, as the time interval occurring between the end of Sm and the onset of Em, were determined as diastolic measurements.