188宝金博页面版

● Original ContributionASSESSMENT OF DIASTOLIC FUNCTION USING ULTRASOUND ELASTOGRAPHYMaryam Vejdani-Jahromi, Jenna Freedman, Young-Joong Kim, Gregg E. Trahey, andPatrick D. WolfBiomedical Engineering Department, Duke University, Durham, NC, USA(Received 9 June 2017; revised 17 November 2017; in f i nal form 20 November 2017)Abstract—Shear wave elasticity imaging (SWEI) is a novel ultrasound elastography technique for assessing tissuestiffness. In this study, we investigate the potential of SWEI for providing diastolic functional assessment. In 11isolated rabbit hearts, pressure-volume (PV) measurements were recorded simultaneously with SWEI record-ings from the left ventricle free wall before and after induction of global ischemia. PV-based end diastolic stiffnessincreased by 100% after ischemia (p < 0.05), and SWEI stiffness showed an increase of 103% (p < 0.05). The re-laxation time constant (τ) before and after ischemia derived from pressure and SWEI curves showed increasesof 79% and 76%, respectively (p < 0.05). Alinear regression between pressure-derived and SWEI-based (τ) showeda slope of 1.164 with R 2 = 0.80, indicating the near equivalence of the two assessments. SWEI can be used to derive(τ) values and myocardial end diastolic stiffness. In global conditions, these measurements are consistent withPV measurements of diastolic function. (E-mail: patrick.wolf@duke.edu) © 2018 World Federation for Ultrasoundin Medicine & Biology. All rights reserved.Key Words: Shear wave imaging, Elastography, Diastolic function, HFpEF, Lusitropy, Isovolumic relaxation timeconstant.INTRODUCTIONHeartfailurewithpreservedejectionfraction(HFpEF)isamajorcause of death, affecting approximately 3 million diagnosedpatients in the United States. It has been shown that approx-imately81%ofHFpEFpatientsexperiencediastolicdysfunction(Writing Group Members et al. 2016). Diastolic dysfunctionis def i ned as the inability of the ventricle to receive a suff i -cientamountofbloodduringdiastole.Histologicstudieshaveshown that myocardial hypertrophy, increased interstitial dis-position of collagen and inf i ltrative mechanisms yield stiffercardiactissue(JeongandDudley2015).Theseprocessesaffectthe active relaxation and passive myocardial properties, dete-rioratingventricularrelaxationandthecomplianceoftheheart.Theisovolumicrelaxationtimeconstant(τ)andventricularstiff-ness (inverse compliance) values have been proposed as twomajor indices for assessment of diastolic function (Burkhoffetal.2005;Gross2009;JeongandDudley2015).Theseindicesare derived experimentally from intra-ventricular pressure-volume (PV) recordings, considered to be the gold standardtechnique; however, this method requires an invasive proce-dure and is not used routinely in the clinic.In clinical practice, the presence of a combination offactors is used to determine the diagnosis of diastolic heartfailure, including the presence of the signs and symp-toms of heart failure, normal ejection fraction and increaseddiastolic pressure or impaired f i lling of the ventricle (Jeongand Dudley 2015). Echocardiography and Doppler imagingusually are used for assessment of diastolic function.However, these measurements can be normal in some con-ditions during the intermediate stages of diastolicdysfunction, an occurrence referred to as pseudonormalizedmeasurements (Oh et al. 2011). Recently, speckle-trackingechocardiography and strain analysis have been used totrack myocardial wall motion during the cardiac cycle(Dusch et al. 2014). These measurements are usually loaddependent and do not provide a direct measurement oftissue stiffness or of the relaxation time constant. In ad-dition, valvular disorders and irregularities in heart rhythmthat could change the atrial mechanics, such as atrial f i -brillation, can affect the accuracy of these measurements(Vorovich et al. 2014). Therefore, it is of great impor-tance to develop a non-invasive technique that can providedirect diastolic functional indices of the myocardium anal-ogous to the PV-derived indices.Addresscorrespondenceto:PatrickWolf,DukeUniversity,BiomedicalEngineering Department, 1427 FCIEMAS, 101 Science Drive, Box 90281,Durham, NC 27708, USA. E-mail: patrick.wolf@duke.eduhttps://doi.org/10.1016/j.ultrasmedbio.2017.11.011Ultrasound in Med. & Biol., Vol. 44, No. 3, pp. 551–561, 2018Copyright © 2018 World Federation for Ultrasound in Medicine & Biology. All rights reserved.Printed in the USA. All rights reserved0301-5629/$ - see front matter551