Isovolumetric Relaxation Time “IVRT” as an Assessment of Left Ventricular Diastolic Function: M-Mode Derived Versus Doppler Derived

Abstract

Background: Isovolumetric Relaxation Time” IVRT” may be defined as: That part of the cardiac cyclebetween the time of aortic valve closure and mitral opening, during which the ventricular muscledecreases its tension without lengthening so that ventricular volume remains unaltered. During this periodthere is a drastic decrease in ventricular pressure without a change in ventricular volume but prior tomitral valve opening. IVRT can be estimated by M-Mode echocardiography with simultaneousphonocardiography or simply by determining the time interval between the maximal systolic excursion ofthe left ventricular posterior wall to the onset of mitral valve opening. More recently, Doppler techniquehas been used to assess not only IVRT but also MPI “Myocardial Performing Index”; comparisons ofDoppler 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 SiemensV.Plus equipment with phased array 2.5MHz probe and PW or CW facilities was used. A good M-modeimage of mitral valve excursion and left ventricular posterior wall systolic excursion was first obtainedand the time between the mitral valve opening and the maximal systolic excursion of LV posterior wallwas then calculated. Doppler IVRT was obtained by directing the Pulsed or continuous wave beam fromapical 5 chamber view across the region between the aortic out flow tract and the mitral inflow tract. Thespectral wave form obtained in this position should include aortic valve flow with valve closure and theonset of mitral inflow with E/A configuration. In this spectrum the aortic closure- mitral opening intervalcan be determined.Results & conclusion: There was no significant difference between M-mode derived IVRT and Dopplerderived IVRT. Since the later has been validated on the ground of correlation with catheterization, thus itseems feasible to use either techniques to assess LV diastolic function.