What is perflutren lipid microspheres (Definity) injection used for?

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Last updated: October 20, 2026 • View editorial policy

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What is Perflutren Lipid Microspheres (Definity) Used For?

Definity is an ultrasound contrast agent used intravenously in both adult and pediatric patients with suboptimal echocardiograms to opacify (brighten) the left ventricular chamber and improve visualization of the left ventricular endocardial border. 1

Primary Clinical Indication

Definity consists of perflutren (octafluoropropane gas) encapsulated in lipid microspheres that enhance ultrasound imaging by increasing the backscatter of ultrasound waves, resulting in enhanced ultrasound signals 1. The agent has no pharmacologic action—it works purely through physical acoustic properties 2.

Specific Clinical Applications

Based on the 2017 European Association of Cardiovascular Imaging guidelines, Definity and similar ultrasound contrast agents are used in several scenarios 3:

Left Ventricular Assessment

  • Endocardial border delineation: When baseline echocardiographic images are suboptimal, Definity improves visualization of the heart wall borders, allowing assessment of wall motion abnormalities
  • Salvage of non-diagnostic studies: In clinical trials, Definity salvaged 48% of non-diagnostic baseline examinations, with an average of 4 additional cardiac segments becoming evaluable per patient 4

Stress Echocardiography

  • Detection of regional wall motion abnormalities for diagnosing coronary artery disease
  • Improved diagnostic accuracy compared to non-contrast stress echocardiography when compared with coronary angiography 3

Additional Diagnostic Uses (Class IIa recommendations)

  • Assessment of left atrial appendage thrombus when native images are inconclusive 3
  • Evaluation of aortic pathology in acute aortic syndromes when non-contrast images are suboptimal 3
  • Distinguishing cardiac masses (tumor vs. thrombus) when CMR is unavailable or inconclusive 3

Dosing and Administration

Adult patients: 10 microL/kg IV bolus over 30-60 seconds, or continuous infusion at 1.3 mL in 50 mL saline starting at 4 mL/minute 1

Pediatric patients (≥1 month): 3 microL/kg IV bolus over 30-60 seconds 1

The duration of clinically useful contrast is approximately 3.4 minutes after bolus injection and 7.1 minutes during continuous infusion 1.

Safety Profile

Definity has a low risk of severe anaphylaxis (0.005%-0.015%), similar to other echo contrast agents, MRI contrast media, and antibiotics 3. Adverse events occur in 1 in 1,000 to 1 in 10,000 patients and are usually mild (headache, nausea, dizziness, back pain, flushing) 3. Most serious reactions occur within 30 minutes of administration 1.

Key Contraindications

  • Known hypersensitivity to perflutren or polyethylene glycol (PEG) 1
  • Previously included intracardiac shunts, but the FDA has lifted this contraindication for Definity 3

Important Clinical Caveat

Echocardiography laboratories using Definity must have resuscitation equipment and trained personnel readily available, with protocols for managing adverse events 3, 1. Staff should have basic life support training and be trained to recognize and treat anaphylactic reactions 3.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.