Isovolumetric Relaxation Time “IVRT” as an Assessment of Left Ventricular Diastolic Function: M-Mode Derived Versus Doppler Derived
Kerbala Journal of Medicine,
2009, Volume 2, Issue 3, Pages 345-351
AbstractBackground: Isovolumetric Relaxation Time” IVRT” may be defined as: That part of the cardiac cycle
between the time of aortic valve closure and mitral opening, during which the ventricular muscle
decreases its tension without lengthening so that ventricular volume remains unaltered. During this period
there is a drastic decrease in ventricular pressure without a change in ventricular volume but prior to
mitral valve opening. IVRT can be estimated by M-Mode echocardiography with simultaneous
phonocardiography or simply by determining the time interval between the maximal systolic excursion of
the left ventricular posterior wall to the onset of mitral valve opening. More recently, Doppler technique
has been used to assess not only IVRT but also MPI “Myocardial Performing Index”; comparisons of
Doppler IVRT with catheterization measurement of this time period have shown reasonable correlations.
Objective: To compare M-Mode derived IVRT with Doppler derived IVRT.
Method: The study was performed on healthy individuals of age of 20-55y. Echo-Doppler Siemens
V.Plus equipment with phased array 2.5MHz probe and PW or CW facilities was used. A good M-mode
image of mitral valve excursion and left ventricular posterior wall systolic excursion was first obtained
and the time between the mitral valve opening and the maximal systolic excursion of LV posterior wall
was then calculated. Doppler IVRT was obtained by directing the Pulsed or continuous wave beam from
apical 5 chamber view across the region between the aortic out flow tract and the mitral inflow tract. The
spectral wave form obtained in this position should include aortic valve flow with valve closure and the
onset of mitral inflow with E/A configuration. In this spectrum the aortic closure- mitral opening interval
can be determined.
Results & conclusion: There was no significant difference between M-mode derived IVRT and Doppler
derived IVRT. Since the later has been validated on the ground of correlation with catheterization, thus it
seems feasible to use either techniques to assess LV diastolic function.
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