Contemporary approved echo contrast agents share a common approved indication of left ventricular opacification and enhancement of endocardial border delineation for the assessment of left ventricular function in patients with technically suboptimal echocardiograms (ECGs). The use of echo contrast agents with advanced imaging technologies has resulted in the conversion of many non-diagnostic ECGs to those of diagnostic quality. The use of echo contrast agents for left ventricular opacification has been shown to be particularly useful in situations in which standard echocardiographic imaging is technically the most challenging, including obesity, chronic pulmonary disease, critically ill patients on respirators, and image acquisition during stress echocardiography.
The accurate assessment of left ventricular ejection fraction is important because it provides important prognostic information in the evaluation and management of patients with cardiovascular disease. Accurate evaluation of regional and global ventricular function by echocardiography is dependent upon adequate endocardial border definition. While native tissue harmonic imaging enables better endocardial definition than standard fundamental imaging and reduces the number of patients with inadequate studies, contrast-enhanced left ventricular opacification confers additional benefits.
The use of echo contrast agents has helped to improve the accuracy of ventricular function and volume measurement by echocardiography in the assessment of left ventricular function compared with standard and fundamental imaging, and is comparable in accuracy with current gold standard techniques such as magnetic resonance imaging and radionuclide angiography. The use of echo contrast agents improves the ability to identify and grade resting wall motion abnormalities, and provides superior endocardial visualization with stress echocardiography. The use of echo contrast agents has resulted in an improvement in interobserver agreement, as well as physician confidence in qualitative and quantitative measurements.
Echo contrast agents are also useful in the enhancement of Doppler signals routinely used for the evaluation of left ventricular and valvular function. The opacification of the blood pool also aids in the structural assessment of cardiovascular anatomy. Clear identification of the endocardial borders helps to facilitate the diagnosis of left ventricular hypertrophy and the apical variant of hypertrophy associated with hypertrophic cardiomyopathy.
Complications of myocardial infarction (MI) have been demonstrated using echo contrast, including myocardial rupture, pseudoaneurysm, and aneurysm formation. The identification of intracardiac masses, including tumors and thrombi, left ventricular non-compaction, and a variety of abnormalities of right ventricular morphology (including right ventricular dysplasia, right ventricular tumor and thrombi), has been facilitated with the use of echo contrast agents. Echo contrast agents can also help to improve visualization of the right ventricle and great vessels.
Echo contrast agents have added a new dimension to the role of ultrasound imaging in cardiology, and help physicians to provide better and safer patient care.