Prediction of viability by pulsed-wave Doppler tissue sampling of asynergic myocardium during low-dose dobutamine challenge

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Abstract

Dobutamine stress echocardiography is widely used to predict reversible left ventricular dysfunction, but evaluation with this method is subjective. Pulsed-wave tissue Doppler imaging is a new technique that allows to obtain quantitative data on wall motion velocities of different myocardial segments through sample-volume placement. Therefore, this tool in combination with DSE may be suitable for identifying viability in asynergic myocardium. To evaluate this, in 40 patients (mean age 57±9) with resting dyssynergy (akinesis in 52, hypokinesis in 30) baseline wall motion scores and tissue Doppler variables were collected before and after 5 min infusion of 10 μg/kg per min dobutamine. Forty-six of 82 segments were classified as viable (a reduction in segmental score of at least one grade) according to follow-up echocardiography that was performed 4 weeks after revascularization. While myocardial S velocity percent increase in viable segments was 45±10, the increase was 25±12 in necrotic segments (n=36) during 10 μg dobutamine infusion (P=0.0001). Assuming 35% as a cut-off for viability the increase in S velocities by DSE yielded an 89% sensitivity and 86% specificity for predicting post-revascularization functional recovery. In conclusion, pulsed-wave tissue Doppler imaging of asynergic myocardium during dobutamine stress echocardiography can identify the viability quantitatively.

Introduction

In coronary artery disease, left ventricular dysfunction may be due to irreversible myocardial fibrosis or hibernation of myocardium [1], [2]. Because revascularization of hibernating myocardium improves left ventricular dysfunction, the distinction between these two features is important [3], [4], [5], [6], [7]. In patients with left ventricular dysfunction, a reliable method for assessing the presence, extent, and location of myocardium with reversible contractile dysfunction is of considerable clinical importance when therapeutic decisions on revascularization procedures are made [8].

Several studies have shown that low-dose dobutamine echocardiography identifies viable myocardium and predicts recovery of left ventricle systolic function after revascularization [6], [9], [10], [11], [12], [13]. However, interpretation of this test is subjective and is highly dependent on training and image quality [14], [15]. Pulsed wave tissue Doppler imaging as a quantitative technique permits analysis of regional myocardial velocities with high spatial and temporal resolution [16], [17]. Although it was reported that the addition of this technique to dobutamine stress echocardiography could allow a more reliable and objective assessment of myocardial segments and identify coronary artery disease effectively [18], [19], reversible contractile dysfunction has not yet been evaluated using this quantitative technique. The aim of the present study was to determine whether analysis of myocardial velocities using pulsed-wave tissue Doppler during low-dose dobutamine echocardiography could be helpful in identifying reversible contractile dysfunction in patients with resting dyssynergy and scheduled for revascularization.

Section snippets

Study patients

Our study group included patients with angiographically documented coronary artery disease and abnormal resting left ventricular functions who were scheduled for coronary revascularization. Abnormal left ventricular function was defined as wall motion abnormalities in at least two adjacent segments by ventriculography. Patients with recent myocardial infarction (<4 weeks), uncontrolled hypertension, severe valvular disease, frequent premature ventricular complexes, atrial fibrillation, poor

Hemodynamic data

A moderate increase in systolic blood pressure (116±9 vs. 124±6 mmHg, P=0.04) and heart rate (82±7 vs. 89±6 beats/min, P=0.02) was observed during infusion of 10 μg/kg dobutamine. Dobutamine echocardiography was well tolerated and no major adverse effects were observed.

Wall motion analysis

According to baseline echocardiographic examination, 82 segments were identified as asynergic (akinesis in 52, hypokinesis in 30 segments). Follow-up echocardiogram showed improvement in 46 of these asynergic segments after

Discussion

The results of present study show: (1) systolic myocardial velocities increase with low-dose dobutamine infusion in both viable and necrotic segments; (2) the systolic myocardial velocity increment in viable segments is higher than the increment in necrotic segments; and (3) the analysis of systolic myocardial velocity increment during low-dose dobutamine infusion predicts viable and necrotic segments with high sensitivity and specificity.

Low-dose dobutamine echocardiography is a frequently

Conclusion

The quantitative analysis of pulsed-wave sampled myocardial velocities during low-dose dobutamine infusion provides an additional benefit to semiquantitative assessment of wall motion for the detection of reversible contractile dysfunction in patients with chronic coronary artery disease and resting dissynergy. Future studies with a larger number of patients will be required to determine the clinical value of the quantitative results given in this study.

References (22)

Cited by (14)

  • Tissue doppler imaging in echocardiography: Value and limitations

    2015, Heart Lung and Circulation
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    The s’ velocity is reduced in ischaemic and infarcted segments [33]. Tissue Doppler imaging has been utilised in dobutamine stress echocardiography (DSE), to objectively quantify ischaemia and will be addressed in the stress echocardiography section. [34,35]. However, TDI is limited by its inability to differentiate active myocardial contraction from the tethering effects of adjacent myocardium (i,e. TDI measures tissue velocity in relation to the transducer rather than to adjacent myocardium), thus lacking site specificity.[36]

  • Pre-ejection mitral annular motion velocity responses to dobutamine infusion: A quantitative approach for assessment of myocardial viability

    2014, Journal of the Saudi Heart Association
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    This means that viable hibernating myocardium may contract at rest when both left ventricular pressure and wall stress are low (e.g. during pre-ejection phase); however, it cannot sustain the higher load during ejection. This is consistent with findings that positive pre-ejection velocity wave is a sign of non-transmural necrosis [25] and that increased segmental systolic velocity during low dose DSE is associated with viability of these segments [26]. Therefore, the pre-ejection wave more sensitively reflects myocardial viability than the ejection wave and gives important information for the detection of reversible myocardial dysfunction (hibernation) with low dose dobutamine stress.

  • Usefulness of quantitative echocardiographic techniques to predict recovery of regional and global left ventricular function after acute myocardial infarction

    2003, American Journal of Cardiology
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    Similarly, a significant increment in global long-axis function is concordant with the radial thickening response to low-dose dobutamine in viable segments.22 A more regional quantitative assessment of viability has been proposed in recent studies,23–25 and these approaches have been validated against single-photon26 and positron tomography.24,27 The prediction of myocardial recovery during follow-up echocardiography has been accomplished by identifying increments in segmental velocity during low-dose dobutamine using pulse-wave tissue Doppler.23,24

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