strain rate imaging   is a spatial derivation of local velocity gradients : sr = error ! , subtracting translational velocities as well as the effects of adjacent segments ( tethering ) and   giving information about the rate of regional deformation . the method has been validated for regional function against wall motion by echocardiography   and coronary angiography . strain rate can be displayed in colour parametric imaging , where orange represents shortening , cyan to blue lengthening ( fig . 1 ) temporal integration of strain rate results in strain , or a direct measurement of regional deformation  analogous to motion , and which have been validated against ultrasonomicrometry   and mr . by the breaking of velocities down to velocity gradients , it can be seen that some events are not simultaneous in all part of the ventricle , especially in diastole . the earliest event in diastole seen by this imaging modality is a protodiastolic lengthening of mid septum , followed by isovolumetric lengthening in the apex and then the early filling phase . thus , the early filling phase is not the earliest diastolic event seen by this imaging modality . early and late filling phases are seen as waves of stretching , propagating from the base to the apex of the ventricle ( fig 1 ) , with a measurable propagation velocity . stretching is equivalent to simultaneous wall thinning   due to the incompressibility of heart muscle . the filling phases may thus be pictured as longitudinal events with simultaneous wall stretching and thinning and hence chamber dilation . peak strain rate is then an index the rate of local wall thinning , and the annulus velocity is the resultant of both ( fig . the strain rate propagation velocity in early filling has been shown to be reduced in delayed relaxation   as well as being load dependent . the flow propagation of early filling in normal ventricles has been shown to consist of an early phase of column propagation , followed by a later phase of vortex propagation . flow propagation have been shown to be reduced in diastolic dysfunction [ 11 - 13 ] . it is considered relatively load independent , although it has been shown to be chamber diameter dependent and thus influenced by dilation . top , still frames from systole showing yellow to red colours of negative strain rate ( shortening ) , and early diastole showing blue to cyan colours of positive strain rate ( lengthening ) . below is shown the resulting m - mode from the same cine - loop of one heart cycle . the numbers to the left refers to the numbers on the 2d images , and are for orientation only . systole ( s ) starts more or less simultaneous in all levels of the ventricle , while early filling ( e ) and atrial systole ( a ) can be seen as waves of stretching propagating from the base to the apex . the principle of propagation velocity measurement as the slope of l/t is shown the ecg is shown at the bottom for reference . is incompressible , systolic shortening has to be balanced by simultaneous wall thickening , and diastolic stretching by thinning , as shown in the upper panel . as the wall gets thinner by diastolic stretching , the transverse diameter of the left ventricle increases . as the wall stretching ( and hence thinning ) propagates from the base to the apex , the early filling phase can be illustrated as a sequence as shown in the lower panel . as strain rate and strain rate propagation are the main indices of myocardial relaxation , they are considered the primary event , and flow propagation the secondary . the aim of this study was to compare the two measures , to establish the relation between them in normal and moderately reduced function , and to assess the influence of other diastolic measurements on flow propagation . 12 control subjects without any evidence of heart disease and 13 patients with hypertension were examined . informed consent was obtained , and the investigation conformed with the principles outlined in the declaration of helsinki . the patients participated in the losartan intervention for endpoint reduction in hypertension ( life ) echo substudy , approved by the national ethical committee . they were selected to the life study according to presence of ecg criteria for left ventricular hypertrophy , randomised to either losartan or atenolol in a blinded design , and additional antihypertensive medication of other types administered as needed . acquisition of additional sri , tissue doppler and colour flow data were done during scheduled control according to study protocol after 1  2 years of treatment . one patient had reduced global ef , moderate left ventricular dilation and reduced flow propagation velocity , but was not excluded in order not to introduce bias . the patients have preserved systolic function ( apart from the one mentioned ) , moderate hypertrophy , and are significantly older than the controls . p values for differences hr : heart rate , bp : blood pressure , ef : ejection fraction , ivsd : septum thickness in diastole , lvdd : left ventricular diameter in diastole . a specially programmed system five scanner ( ge vingmed ultrasound , horten , norway ) with a sri was processed online on the scanner , and cine - loops of all three standard apical planes were recorded and transferred to a pc computer for analysis in a dedicated software . frame rate was 70  100 fps and offset length ( strain rate sample volume ) 5  7 mm . linear propagation velocity of strain rate during early diastole ( pvse ) was measured along the front of peak strain rate as shown in fig 1 , in all 6 walls of each ventricle , and averaged for each subject . peak strain rate during early filling ( sre ) was measured in all 16 standard segments   of the left ventricle and averaged for each subject . standard echocardiographic recordings were acquired during the same examination and transferred to a macintosh computer for off - line analysis in echopac ( ge vingmed ultrasound , horten , norway ) . ejection fraction ( ef ) was measured by modified biplane simpson 's method in apical 4-chamber and long - axis planes in the octave mode . intraventricular septum thickness ( ivsd ) and left ventricular internal diameter ( lvidd ) at end diastole were measured in parasternal m - mode . mitral flow for measurement of deceleration time of early filling ( dec .- t ) , peak transmitral flow velocity ( e ) , peak flow velocity during atrial systole was acquired from a position between the tips of the mitral leaflets . isovolumic relaxation time ( ivr ) was measured by pulsed doppler in a position between aortic orifice and mitral inflow ; valve click of aortic closure and start of mitral flow was used . colour m - mode of intraventricular flow was obtained with a pulse repetition frequency of 3 khz , and flow propagation velocity during early filling ( pvfe ) was measured as shown in fig . as the value of flow propagation depends on the method used : black  to colour transition , front of first aliased contour   or main vector   as shown in fig 4 , all three values was measured for comparison of results and variability . peak velocity of the mitral annulus during early diastole ( ea ) was measured by pulsed wave tissue doppler at four points of the annulus and averaged for each subject . flow propagation . the two phases of early filling phase i or column propagation and phase ii or vortex propagation described by steen & steen ( 12 ) are also visible . high flow velocity propagation of phase i , evidenced by the upright column is seen . in addition there is very little phase ii propagation , indicating a narrow ventricle during early filling . bottom : from a patient with slightly dilated lv of 65 mm and ef of 45% . the main velocity propagation is phase ii , vortex propagation with a low propagation velocity . flow propagation measurement the slope of the line and thus the value for flow propagation is dependent on the contour chosen . p - values for differences between patients and controls are two - tailed probabilities by two - tailed student 's t - test . all significant differences were also significant by wilcoxon 's two - sample rank sum test . relation between flow propagation velocity ( dependent ) and various variables is by univariate and multiple linear regression . diastolic measurements of flow , tissue doppler and strain rate are shown in table 2 . the main finding is that strain rate propagation is reduced , while flow propagation velocity is increased in the patient group , contrary to previous findings . correspondingly there is a significant negative correlation between the two values : r = -0.57 ( 95% ci -0.23 to -0.79 , p < 0.005 ,  = -0.54 p < 0.005 ) . there was a significant negative correlation between strain rate propagation velocity and deceleration time of mitral flow : r = -0.51 , ( -0.15 to -0.75 , p < 0.05 , = -0.48 , p < 0.05 ) . b ; strain rate propagation vs. deceleration time . as strain rate propagation increases   velocity filling time decreased . bottom , ratio of peak early mitral flow velocity / strain rate propagation ( e / pvse ) vs. flow propagation showing a positive correlation . the patients show near normal peak mitral flow velocity , near normal , but still reduced e / a ratio compared to controls , and deceleration time of mitral flow velocity and ivr are prolonged in the patient group . early diastolic annulus velocity and strain rate are reduced in the patient group , showing a moderate diastolic dysfunction . the ratio of mitral flow and annulus velocity , e / ea was 5,4 in the control group , and 7.4 in the patient group , the difference is significant , but still indicates normal filling pressure in both groups . in univariate linear regression , only the correlation between strain rate propagation and flow propagation is significant ( p = 0.003 ) . no significant relation is found between flow propagation velocity and peak annular early diastolic velocity , left ventricular diastolic diameter , peak early diastolic strain rate , deceleration time of early mitral flow , isovolumic relaxation , hr , ef or age , in either univariate or multivariate analysis . strain rate propagation velocity is significant in both univariate and multivariate ( p = 0.004 ) analysis . peak mitral flow velocity is not significant in univariate analysis , only in multivariate ( p = 0.017 ) , showing interaction with strain rate propagation velocity ( significance of the interaction : 0.014 ) . thus , there is a significant correlation between the ratio : peak early mitral flow velocity / strain rate propagation ( e / pvse ) and flow propagation velocity , pvfe : r = 0.67 , ( 0.37  0.84 , p < 0.001 ,  = 0.58 , p < 0.002 ) . 95% limits of agreement for strain rate propagation velocity ( bland  altman statistics ; average difference  2sd of differences between repeated measurements ) was ( -29.4 ; 32.5 cm / s ) by intraobserver and ( -24.2 ; 36.6 cm / s ) by interobserver study . in the present study , strain rate propagation velocity has standard error of the mean of 3.44 in controls , and 2.67 in patients , while flow propagation has standard error of 1.59 and 3.75 respectively . flow propagation was measured in the same files with an interval of one year , by the same investigator . the intraobserver limits of agreement were ( -33.3 ; 52.1 cm / s ) , showing a low precision . the difference between patients and controls , and the negative correlation with strain rate propagation velocity , however , remained significant . comparison of three methods for measuring flow propagation is summarised in table 3 , showing the front of aliased contour to give the best precision . comparison of flow propagation velocity measurements by three methods p : significance of the differences between the two groups ( standard deviation in parentheses ) . r : correlation with strain rate propagation velocity ( 95% confidence intervals in parentheses ) . diastolic measurements of flow , tissue doppler and strain rate are shown in table 2 . the main finding is that strain rate propagation is reduced , while flow propagation velocity is increased in the patient group , contrary to previous findings . correspondingly there is a significant negative correlation between the two values : r = -0.57 ( 95% ci -0.23 to -0.79 , p < 0.005 ,  = -0.54 p < 0.005 ) . there was a significant negative correlation between strain rate propagation velocity and deceleration time of mitral flow : r = -0.51 , ( -0.15 to -0.75 , p < 0.05 , = -0.48 , p < 0.05 ) . b ; strain rate propagation vs. deceleration time . as strain rate propagation increases   velocity filling time decreased . bottom , ratio of peak early mitral flow velocity / strain rate propagation ( e / pvse ) vs. flow propagation showing a positive correlation . the patients show near normal peak mitral flow velocity , near normal , but still reduced e / a ratio compared to controls , and deceleration time of mitral flow velocity and ivr are prolonged in the patient group . early diastolic annulus velocity and strain rate are reduced in the patient group , showing a moderate diastolic dysfunction . the ratio of mitral flow and annulus velocity , e / ea was 5,4 in the control group , and 7.4 in the patient group , the difference is significant , but still indicates normal filling pressure in both groups . in univariate linear regression , only the correlation between strain rate propagation and flow propagation is significant ( p = 0.003 ) . no significant relation is found between flow propagation velocity and peak annular early diastolic velocity , left ventricular diastolic diameter , peak early diastolic strain rate , deceleration time of early mitral flow , isovolumic relaxation , hr , ef or age , in either univariate or multivariate analysis . strain rate propagation velocity is significant in both univariate and multivariate ( p = 0.004 ) analysis . peak mitral flow velocity is not significant in univariate analysis , only in multivariate ( p = 0.017 ) , showing interaction with strain rate propagation velocity ( significance of the interaction : 0.014 ) . thus , there is a significant correlation between the ratio : peak early mitral flow velocity / strain rate propagation ( e / pvse ) and flow propagation velocity , pvfe : r = 0.67 , ( 0.37  0.84 , p < 0.001 ,  = 0.58 , p < 0.002 ) . 95% limits of agreement for strain rate propagation velocity ( bland  altman statistics ; average difference  2sd of differences between repeated measurements ) was ( -29.4 ; 32.5 cm / s ) by intraobserver and ( -24.2 ; 36.6 cm / s ) by interobserver study . in the present study , strain rate propagation velocity has standard error of the mean of 3.44 in controls , and 2.67 in patients , while flow propagation has standard error of 1.59 and 3.75 respectively . flow propagation was measured in the same files with an interval of one year , by the same investigator . the intraobserver limits of agreement were ( -33.3 ; 52.1 cm / s ) , showing a low precision . the difference between patients and controls , and the negative correlation with strain rate propagation velocity , however , remained significant . comparison of three methods for measuring flow propagation is summarised in table 3 , showing the front of aliased contour to give the best precision . comparison of flow propagation velocity measurements by three methods p : significance of the differences between the two groups ( standard deviation in parentheses ) . r : correlation with strain rate propagation velocity ( 95% confidence intervals in parentheses ) . strain rate propagation is a measure of the rate of chamber expansion as illustrated in fig 1 . deceleration time of early mitral flow is a measure of filling time , and the negative correlation is as expected . thus , strain rate propagation may be taken as a measure of left ventricular filling dynamics during early diastole . flow propagation velocity and strain rate propagation velocity are similar in the control group . while strain rate propagation decreases in the patient group , consistent with delayed relaxation , this finding is contrary to previous findings [ 11,12,14,19 - 22 ] , and unexpected in view of the reduced strain rate propagation , and the negative correlation between strain rate propagation and flow propagation velocity , is consistent with this finding . measurements of propagation velocities have a low precision , as shown by the wide limits of agreements , and the variability given in table 3 . the actual value of flow propagation velocity depends on the method chosen , as shown in table 3 and fig . , measurements are dependent on scanner settings : black - to - colour transition depends on the level of low velocity rejection , the aliasing contour on pulse repetition frequency . comparing different studies is therefore difficult , as shown by the variety of normal values given , and also for methodological reasons , flow propagation velocity has limited value as an index of diastolic function . on the other hand , the low precision of flow propagation can not explain the significance of the results , as low precision alone will result in random , rather than systematic variation . previous studies have all shown reduced flow propagation velocity in reduced diastolic function . however , in many of those studies , there was simultaneous left ventricular dilation . it has been demonstrated that in left ventricular dilation , there is no column propagation , but solely vortex propagation , as the main mechanism for the flow propagation delay . in the present study , there was no left ventricular dilation ( except in the one patient commented on ) , on the contrary , there was a non - significant trend toward a narrowing of the ventricle due to concentric hypertrophy . in addition slower strain rate propagation causes the ventricle to remain narrow for a longer time during early filling . however , also in ordinary ageing and in hypertrophic cardiomyopathy , where no dilation is to be expected , there is found delayed flow propagation . thus , the characteristics of the patient group itself may be a factor in these results . -the patient group had delayed relaxation , as evidenced by the prolonged deceleration time and ivr as well as reduced early diastolic mitral annulus velocity by tissue doppler . the e / a ratio but not the e flow velocity was reduced , but the pattern is more normal than in other studies . there was a significant difference in e / ea ratio , but it was below the cut off value of 8 in both groups , so there was no indication of pseudonormalised mitral flow , although a difference in filling pressure within the normal range can not be excluded . the main reason for the high early diastolic flow velocity seems thus to be very moderately reduced diastolic function . i.e. the interaction with strain rate propagation velocity was shown to be a determining factor by multivariate analysis . a correlation between flow propagation velocity and the ratio of mitral flow velocity and strain rate propagation velocity ; e / pvse , will result in normal flow propagation in normals ( fig 6a ) , increased flow propagation velocity in delayed relaxation with higher e velocity ( 6b ) and reduced flow propagation in delayed relaxation with low e velocity ( 6c ) . b : prolonged deceleration time , but near normal e velocity and e / a ratio . c : delayed relaxation with severely prolonged deceleration time , reduced e velocity and e / a ratio . both in a and c , the flow propagation velocity may match strain rate propagation velocity , if the relation e / pvse holds true . this , however , means that flow propagation velocity is not a simple index of diastolic function , but rather a composite function of more factors , in addition to a low precision . the importance of mitral flow velocity in relation to flow propagation have been found also by others   the reduced diastolic function in the patient group was due to a combination of age   and hypertension with moderate hypertrophy . this was considered acceptable , in view of the object of the study , the mechanics of filling , not causes of diastolic dysfunction . the function seems to be similar , irrespective of causes , but it still remains a limitation . results will have no relevance in dilated ventricles , as they do not concern vortex propagation , nor to regional dysfunction where flow pattern is shown to be more complex due to regional disturbances . strain rate imaging shows the ventricular deformation during early filling to be a dynamic event that is slowed in subjects with delayed relaxation . the strain rate propagation is the main determinant of the filling rate , and is consistent with filling time . flow propagation velocity , in this study , was found to be significantly increased in patients with delayed relaxation , and was shown to be dependent on both strain rate propagation and mitral inflow velocity , and is thus not a simple index of diastolic function . neither strain rate propagation nor flow propagation velocities do at present show the precision necessary for clinical use . gs recruited the patients to the primary study , and referred them to the ultrasound sub study . bjrn olstad , of ge vingmed ultrasound , horten , norway , programmed the special software for strain rate analysis .