* Based on a single-center study of adult patients (age >18 years) receiving a UEA (LUMASON^®, Optison™, or Definity^®) were prospectively evaluated for clinically significant adverse events defined as either anaphylactoid reactions (rash, flank pain, dyspnea, and wheeze) or true anaphylaxis. Study objectives included the following: determining the major adverse reactions experienced by patients receiving UEA in a clinical setting, assessing whether microbubbles are safe for use in patients with intra-cardiac shunts, and assessing whether the types of adverse reactions differ significantly among the three FDA-approved UEAs.