Letter by Weidemann et al Regarding Article, “Global Diastolic Strain Rate for the Assessment of Left Ventricular Relaxation and Filling Pressure”
To the Editor:
We have read with interest the paper by Wang et al1 on diastolic function assessed by strain rate in the isovolumetric relaxation period (SRIVR) derived from 2-dimensional speckle tracking. In principle, 2-dimensional speckle tracking is a useful progression toward an automated assessment of left ventricular deformation.
We would like to comment on the fact that the authors had some difficulties with patients with wall motion abnormalities. It is known from many studies that different conditions such as acute ischemia, regional fibrosis, and increased afterload result in ongoing (postsystolic) deformation during isovolumic relaxation (IVR).2,3 This deformation will change local SRIVR independently from tau, which thus limits the assessment of diastolic function by analysis of SRIVR in a wide range of important clinical conditions.
In addition, we agree that E/Ea has some limitations when diastolic function is assessed, especially in the gray zone between 8 and 15. However, although it has merits in the assessment of strain, we think that 2-dimensional speckle tracking is not satisfactory when strain rate is assessed, especially during IVR. It is well known that speckle tracking can only be performed at relatively low frame rates. However, this low frame rate prevents resolution of the fast change in deformation (ie, strain rate) that occurs during IVR. This lack of resolution leads, as correctly mentioned in the paper,1 to an underestimation of peak strain-rate value. Thus, we would suggest use of Doppler-derived strain rate (with its high temporal resolution), and not speckle tracking strain rate, to accurately assess SRIVR.
The authors could nicely show the limitations of diastolic function assessment by pulsed-wave tissue Doppler imaging and suggest a greater focus on diastolic deformation. However, we believe that assessment of strain rate during IVR with 2-dimensional speckle tracking and its inherent technical limitations will prove a real challenge in clinical conditions.
Wang J, Khoury DS, Thohan V, Torre-Amione G, Nagueh SF. Global diastolic strain rate for the assessment of left ventricular relaxation and filling pressures. Circulation. 2007; 115: 1376–1383.
Weidemann F, Dommke C, Bijnens B, Claus P, D’hooge J, Mertens P, Verbeken E, Maes A, Van de Werf F, De Scheerder I, Sutherland GR. Defining the transmurality of a chronic myocardial infarction by ultrasonic strain-rate imaging: implications for identifying intramural viability: an experimental study. Circulation. 2003; 107: 883–888.
Voigt JU, Lindenmeier G, Exner B, Regenfus M, Werner D, Reulbach U, Nixdorff U, Flachskampf FA, Daniel WG. Incidence and characteristics of segmental postsystolic longitudinal shortening in normal, acutely ischemic, and scarred myocardium. J Am Soc Echocardiogr. 2003; 16: 415–423.