On October 10, 2014 the FDA gave approval a Lumason (SonoVue, Bracco Diagnostics) to be used in the U.S. for contrast enhancement during echocardiography. It is unique in that its lipid microsphere stabilizing shell contains sulfur hexafluoride gas rather than perflutren. Like all currently FDA approved contrast agents, it carries a black box warning for acute cardiopulmonary reactions in the 30 minutes following administration,and showed not be used in patients with right-to-left cardiac shunts.
A patient’s body habitus may limit sonographic windows technically limiting the echocardiogram study. Echocardiographic contrast agents in this situation can be useful to help with interpretation. Contrast, usually a form of gas bubble that scatters ultrasound waves, is used for two principle reasons: to detect left to right shunts and to opacify the left ventricle to define the endocardial border, which allows better determination of ventricular dimensions, wall motion, and ejection fraction. Contrast is given intravenously, and it needs to transverse the pulmonary circuit to opacify the left ventricle. Larger bubbles are more stable, but the bubbles need to be less than 10 micrometers to pass through the pulmonary capillaries. Microbubbles less than 2 micrometers do not provide enough scattering to be useful for opacification. The bubbles can be stabilized by surrounding them with a durable structure and using inert gases rather than air.
The table below lists commonly used echo contrast agents.