Tissue Doppler velocity imaging and event timings in neonates: a guide to image acquisition, measurement, interpretation, and reference values

Abstract

Neonatologists can use echocardiography for real-time assessment of the hemodynamic state of neonates to support clinical decision-making. There is a large body of evidence showing the shortcomings of conventional echocardiographic indices in neonates. Newer imaging modalities have evolved. Tissue Doppler imaging is a new technique that can provide measurements of myocardial movement and timing of myocardial events and may overcome some of the shortcomings of conventional techniques. The high time resolution and its ability to assess left and right cardiac function make tissue Doppler a favorable technique for assessing heart function in neonates. The aim of this review is to provide an up-to-date overview of tissue Doppler techniques for the assessment of cardiac function in the neonatal context, with focus on measurements from the atrioventricular (AV) plane. We discuss basic concepts, protocol for assessment, feasibility, and limitations, and we report reference values and give examples of its use in neonates.

Conflict of interest statement

A.E.K. is in receipt of an Irish Health Research Board Clinical Trials Network Grant (HRB CTN 2014-10) and an EU FP7/2007-2013 grant (agreement no. 260777, The HIP Trial). A.G. owned equity in Neonatal Echo Skills and has received grant support from the American Heart Association. D.V.L. is in receipt of an EU FP7/2007-2013 (agreement no. 260777 the HIP trial). E.D. received lecture fees and consulting fees from Chiesi Pharmaceutical. E.N. received grant support from Research Council of Norway and Vestfold Hospital Trust. K.B. received lecture fees from Chiesi Pharmaceutical. M.B. holds a patent, “Thermal shield for the newborn baby”. S.G. received grant support from National Institute of Health Research, Health Technology Assessment (11/92/15), UK. S.R. received lecture fees for Phillips Ultrasound and GE Ultrasound. W.P.B. has received grant support from The Netherlands Organization for Health and Development (ZonMw; grant number 843002622 and 843002608). Z.M. has received lecture fees from Chiesi Pharmaceutical. All the remaining authors declared no competing interests.

Figures

Fig. 1

Pulsed-wave tissue Doppler velocity measurement from a term neonate, from the right lateral atrioventricular plane from the apical four-chamber view. The ultrasound system records the velocities from the area between the two calipers (the two white solid lines in the upper left panel). The dotted line denotes the direction of the ultrasound beams assessing the velocities. (Upper left panel) a Color-coded tissue Doppler image. (Upper right panel) b Spectral velocity time curve of three heart cycles, with relatively high gain setting. The upper panels (a and b) show a relatively poor image quality (blurred 2D image (a) and a broad spectral velocity–time curve (b). The lower panel c shows a velocity curve with narrower spectral curve, indicating better quality. X-axis: time. Y-axis: tissue velocity from the sample area. White arrows at the peak systolic velocities (s′), red arrows at the early diastolic velocities (e′), and green arrows at the peak velocity in atrial systole (a′)

Fig. 2

The upper panels show color-coded tissue Doppler velocity curve from a term neonate, from the left lateral atrioventricular plane from the apical four-chamber view. The upper left panel a shows the echocardiographic image with a sample area of 3 mm diameter (yellow circle). The curve in the upper right panel b shows the tissue velocities from the sample area. The lower panel c shows pulsed-wave tissue Doppler velocity curve from the septal hinge atrioventricular plane from the apical four-chamber view of a term neonate. White arrows at the peak systolic velocity (s′), red arrows at the early diastolic velocity (e′), and green arrows at the peak velocity in atrial systole (a′). The vertical lines denote the events defining the four phases of the heart cycle; isovolumic contraction, ejection phase, isovolumic relaxation, and filling. Note that the velocity curves in the isovolumic phases (1 and 3) contain one negative peak adjacent to the ejection phase and one positive peak adjacent to the filling phase, most evident in the color-coded measurements. Blue vertical lines denote closure of the mitral valve. Red vertical line denotes opening of the aortic valve. Green vertical line denotes closure of the aortic valve. White vertical line denotes opening of the mitral valve. White circles denote the peak isovolumic contraction velocity. X-axis: time. Y-axis: tissue velocity from the sample area

Fig. 3

Same color-coded tissue Doppler velocity recording as in upper panel of Fig. 2, the curve now shows the displacement of the sample area. White arrow at the peak systolic displacement. Blue arrow at the peak displacement, occurring early in diastole in this image. Peak (global) displacement can also occur in systole. Blue vertical lines denote closure of the mitral valve. Red vertical line denotes opening of the aortic valve. Green vertical line denotes closure of the aortic valve. White vertical line denotes opening of the mitral valve. X-axis: time. Y-axis: displacement assessed by velocities from the sample area

Fig. 4

Example of non-aliased and aliased velocity measurements. Both panels show a color tissue Doppler velocity measurements of the right lateral atrioventricular plane in three consecutive heartbeats in a term neonate. The left part of both panels a and c show an apical four-chamber image with a sample area (yellow circle) of 3 × 3 mm. The right panels b and d show the velocity curves. The velocity scale is ±0.16 m/s in the upper panel and ±0.08 m/s in the lower panel. The negative peak velocity in diastole is approximately −0.09 m/s (blue arrows), within the velocity range in the upper panel but outside the velocity range in the lower panel. The ultrasound system therefore shows the velocity correctly in the upper panel and erroneously as a positive velocity close to the upper velocity limit in the lower panel. Note that there is complete fusion of diastolic velocities in the last two heart-cycles in the upper panel; it is not possible to identify two diastolic velocity peaks. X-axis: time. Y-axis: tissue velocity from the sample area

Fig. 5

Pitfalls in image acquisition and analysis of pulsed-wave tissue Doppler images. The upper panel shows small breaks in the spectral curve when the ultrasound system records 2D images and pulsed-wave tissue Doppler spectral curve simultaneously. The a′ is false low in the second of the three heartbeats because the ultrasound system recorded the 2D image instead of the spectral curve at the time-point for the late diastolic peak (white arrow). The lower panel shows the systolic phase of one heart cycle with assessment of s′ velocity by correct (a) and by too high (b) gain setting. Measurement #1 is the correct velocity (5.1 cm/s) and measurement #2 is a false high velocity (6.1 cm/s). The only difference between the lower left and right panels is the gain setting during the off-line analysis

Fig. 6

Same loop as in upper panel of Fig. 2, color-coded tissue Doppler velocity curves from a term neonate from the left lateral atrioventricular plane from the apical four-chamber view. The left curve (a) shows the velocities without time smoothing and the right curve (b) shows the velocities with too much time smoothing. Too much and too little time smoothing make interpretation of the curves difficult. Note that it is hard to identify the isovolumic contraction phase, especially in the right panel where the negative slope prior to the ejection phase is missing. Blue vertical lines denote closure of the mitral valve. Red vertical line denotes opening of the aortic valve. Green vertical line denotes closure of the aortic valve. White vertical line denotes opening of the mitral valve