Grading of Myocardial Dysfunction by Tissue Doppler Echocardiography
A Comparison Between Velocity, Displacement, and Strain Imaging in Acute Ischemia
Helge Skulstad, MD,
Stig Urheim, MD,
Thor Edvardsen, MD, PhD,
Kai Andersen, MD, PhD,
Erik Lyseggen, MD,
Trond Vartdal, MD,
Halfdan Ihlen, MD, PhD and
Otto A. Smiseth, MD, PhD*
Department of Cardiology and the Institute for Surgical Research, Rikshospitalet University Hospital, Oslo, Norway
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Figure 1 Changes in left ventricular (LV) pressure-segment length loops during ischemia and increase in afterload from a representative experiment. The isovolumic contraction (IVC) and isovolumic relaxation (IVR) phases are indicated. The loops during baseline and left anterior descending coronary artery (LAD) stenosis rotate counterclockwise, indicating net actively contracting segments. During LAD occlusion the loops rotate clockwise, indicating that the segment behaves passively during systole. Aortic constriction superimposed on LAD stenosis changed segment behavior from active to passive.
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Figure 2 Tissue velocity, displacement, strain, and sonomicrometry traces from the mid left ventricular anterior wall in a representative experiment at baseline and during ischemia. Note that peak systolic ejection velocity was essentially similar at different levels of ischemia while systolic strain and displacement were markedly different. Ao = aortic; ECG = electrocardiogram; LA = left atrium; LV dP/dt = time derivative of LV pressure. Other abbreviations as in Figure 1.
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Figure 3 Velocity (V), strain (S), and displacement (D) measurements from individual experiments (n = 10) at baseline (bl), left anterior descending coronary artery stenosis (st), left anterior descending coronary artery stenosis and aortic constriction (st + ao, n = 6), and, finally, left anterior descending coronary artery occlusion (occ). For most variables, there was substantial overlap between the different measurement conditions. Thus, systolic ejection velocity did not discriminate well between baseline and different levels of ischemic dysfunction. Strain and displacement discriminated better between left anterior descending coronary artery stenosis and occlusion. Mean and standard deviation are indicated. *p < 0.01 vs. baseline;  p < 0.05 vs. baseline;  p < 0.05 vs. left anterior descending coronary artery occlusion;  p < 0.05 vs. left anterior descending coronary artery stenosis; #p < 0.01 vs. left anterior descending coronary artery stenosis. Other abbreviations as in Figure 1.
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Figure 4 Scatterplot of the relation between the tissue Doppler imaging parameters and strain by sonomicrometry and segment work as reference methods. Systolic strain and displacement showed excellent correlation with both reference methods. Although there were significant correlations between systolic velocity and both reference methods, velocity could not separate passive (negative work) from active (positive work) segments. Systolic strain and displacement, however, differentiated well between active and passive segments. Open circles = baseline; solid squares = left anterior descending coronary artery stenosis; solid triangles = left anterior descending coronary artery occlusion.
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Figure 5 Systolic measurements in six regions in the anterior wall (apical two-chamber view) in patients with acute left anterior descending coronary artery occlusion (n = 10) (solid diamonds) and healthy volunteers (n = 15) (open diamonds). In the infarction group, the velocity and displacement were reduced in every segment relative to the control group. The strain values, however, dropped markedly in the mid- and apical segments, consistent with infarction in these segments. Aa = apical segment, apical part; Ab = apical segment, basal part; Ba = basal segment, apical part; Bb = basal segment, basal part; Ma = mid-segment, apical part; Mb = mid-segment, basal part. Mean and standard deviation are indicated. *p < 0.01 vs. healthy volunteers; p < 0.05 vs. healthy volunteers. NS = not significant vs. healthy volunteers.
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Figure 6 Representative recordings from the anterior wall in a patient with acute myocardial infarction (left anterior descending coronary artery [LAD] occlusion). A standard echocardiographic apical two-chamber view was used. ECG = electrocardiogram.
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Figure 7 Effect of change in position of the ultrasound probe on velocity, displacement, and strain measurements. Dislocating the position of the echocardiographic probe medially aiming a deviation of the ultrasound insonation angle by approximately 30° had different impacts on the angle between the ultrasonic beams and the ventricular wall in the various segments. Values are given in percentage relative to measurements from apical position.
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