Cardiac Arrest From Sulfur Hexafluoride Contrast Anaphylaxis After Prior Perflutren Hypersensitivity

BACKGROUND: Ultrasound-enhancing agents (UEAs) are generally considered safe, with severe reactions exceptionally rare. Cross-reactivity between agents remains poorly understood. CASE SUMMARY: A 62-year old man with prior hypersensitivity to perflutren lipid microspheres contrast agent developed anaphylaxis with pulseless electrical activity arrest immediately after administration of sulfur hexafluoride lipid microspheres contrast agent. After resuscitation, return of spontaneous circulation occurred within 2 minutes. An elevated tryptase level confirmed mast cell activation. DISCUSSION: Current guidelines support the use of sulfur hexafluoride lipid microspheres in patients with hypersensitivity to perflutren lipid microspheres given an absence of established cross-reactivity between contrast agents. This case underscores the potential for life-threatening anaphylactic reactions to UEAs, even in patients with prior documented tolerance to related formulations. TAKE-HOME MESSAGES: This is to our knowledge the first reported case of sulfur hexafluoride lipid microspheres anaphylaxis resulting in cardiac arrest in a patient with prior hypersensitivity to perflutren lipid microspheres. Clinicians should anticipate cross-sensitization between UEAs and maintain immediate access to resuscitation measures.