Figure 1: Apical 4 chamber view of the Left Ventricle with standard two-dimensional imaging.
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Figure 2: Apical 4 chamber view of the Left Ventricle with opacification.
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Figure 3: Apical 4 chamber view of the Left Ventricle with myocardial perfusion imaging.
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Figure 4: An example of a single vessel disease on myocardial perfusion imaging. The blackened area in the apical 4 chamber apex shows left anterior descending disease.

Echocardiography has developed an invaluable role as a routine technique for the assessment of ventricular and valvular structure and function, but traditionally has been unable to assess myocardial perfusion, Figure 1.

Contrast approaches have been combined with echocardiography for over 20 years, because the reflectivity of these bubbles to ultrasound facilitates the visualization of whatever structure contains the bubbles.  Development of sonication techniques permitted development of microbubbles of <6ìm diameter that are able to cross the pulmonary microcirculation after peripheral injection. The resulting opacification of the LV cwmvty readily enhances delineation of the LV border, Figure 2. The myocardial blush has been evaluated qualitatively; bubble destruction permits evaluation of the rate of replenishment, which corresponds to blood flow, Figure 3.

The work of this and other groups has shown myocardial contrast echo (MCE) to add to the sensitivity of stress echo  especially for the detection of single vessel disease (Figure 4) and assessment of the true extent of involvement in multivessel disease. These and other recent studies have been performed in collaboration with the PA Hospital Cardiac Catheterisation laboratory and Nuclear Medicine Department. 

However, our economic modeling based on these results suggests that the cost-effectiveness of adding contract is only realized if event rates are high. We are currently evaluating the cost-effectiveness of contrast echo in a large prospective series.

Personnel

• Brian Haluska (sonographer)
• Carly Jenkins (sonographer)
• Stuart Moir (PhD Student)
• Professor Tom Marwick