[Contrast echocardiography: clinical applications and future prospects]

Contrast echocardiography has been used as a clinical method for more than 20 years. Using conventional ultrasound techniques the clinical use of contrast was limited. Now the development of "contrast specific" imaging modalities has increased the indications for contrast echocardiography.

For clinical use two classes of contrast agents are available: 1. "right heart" contrast media (Echovist, agitated solutions), which do not cross the pulmonary vascular bed following intravenous injection and which can be used with conventional (fundamental) imaging methods, 2. "left heart" contrast media (Levovist, Optison, SonoVue) which need "contrast specific" imaging modalities for optimal use.

Despite of the developments in Doppler methods and transesophageal echocardiography "right heart" contrast media still are needed in some patients with atrial and pulmonary shunts, complex congenital heart disease, noisy Doppler recordings of tricuspid regurgitation. For "left heart" contrast media improvement of endocardial border definition is the most important indication, which has been validated in a series of well performed studies. Therefore contrast enhanced recordings are recommended in the clinical echo laboratory when unenhanced recordings are suboptimal. Coronary flow reserve of the LAD can be measured using contrast enhanced Doppler echocardiography. All contrast specific imaging modalities provide assessment of myocardial perfusion. The previously used imaging modalities (Harmonic B mode, Pulse Inversion and Harmonic Power Doppler) did not provide sufficient myocardial contrast signals using real-time imaging. Although intermittent imaging resulted in good myocardial opacification, this modality did not gain wider clinical acceptance.

Using new contrast specific imaging technologies like Power Pulse Inversion, Power Modulation and Coherent Imaging myocardial perfusion can be evaluated in "real-time". Thus simultaneous assessment of left ventricular wall motion and myocardial perfusion became a reality and facilitated the data acquisition. New ultrasound contrast media like SonoVue can be used for all imaging modalities. Recent studies have demonstrated that the information derived from myocardial contrast echocardiography provides clinically relevant information on top of the findings obtained from conventional left ventricular wall motion analysis.