Definity RT is an ultrasound contrast agent that is used to improve the quality of an echocardiogram (ultrasound of the heart). This medicine works by changing the way ultrasound waves travel within your heart. This helps the ultrasound portray a sharper image of your heart.

Definity RT is used to allow certain segments of the heart to be seen more clearly on an echocardiogram.

Definity RT may also be used for purposes not listed in this medication guide.

Serious side effects may occur during the injection. Tell your caregiver if you feel dizzy, nauseated, light-headed, short of breath, or if you have a severe headache, pounding in your ears, chest pain, fast or slow heartbeats, wheezing, or shallow breathing.

You may be more likely to have a serious reaction if you have severe or uncontrolled heart problems (congestive heart failure, a recent heart attack, serious heart rhythm disorder).

Definity RT is given as an infusion into a vein. A healthcare provider will give you this injection just before the start of your echocardiogram.

Your heart rate, breathing, blood pressure, oxygen levels, and other vital signs will be watched closely for at least 30 minutes after you receive Definity RT. This is to make sure you do not have an allergic reaction to the medicine.

You should not be treated with Definity RT if you are allergic to Definity RT, polyethylene glycol or albumin.

Tell your doctor if you have ever had:

• a congenital heart defect;

• a lung condition that has recently become worse; or

• if you have ever had an allergic reaction during a blood transfusion.

Tell your doctor if you are pregnant or breastfeeding.

Since Definity RT is given with an echocardiogram, you will not be on a regular dosing schedule.

Since Definity RT is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives, skin redness, itching; warmth, redness, numbness, or tingly feeling; wheezing, trouble breathing, tightness in your chest or throat; swelling of your face, lips, tongue, or throat.

In rare cases, serious or fatal reactions may occur during the injection or shortly afterward. Tell your caregivers right away if you have:

• a light-headed feeling, like you might pass out;

• severe dizziness, or a cold sweat;

• chest pain, wheezing, trouble breathing;

• fast or slow heartbeats;

• severe headache, blurred vision, pounding in your neck or ears, anxiety, confusion; or

• slow heart rate, weak pulse, fainting, weak or shallow breathing.

You may be more likely to have a serious reaction if you have severe or uncontrolled heart problems (congestive heart failure, a recent heart attack, serious heart rhythm disorder).

Common side effects of Definity RT may include:

• headache, dizziness;

• flushing (warmth, redness, or tingly feeling);

• nausea;

• chest pain;

• pain in your side or lower back; or

• pain, swelling, or irritation where the injection was given.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may affect Definity RT, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.