Hemolysis in vivo from exposure to pulsed ultrasound

Abstract

Listen

Translate article

Ultrasonically induced hemolysis in vivo was studied when a commercial ultrasound contrast agent, Albunex ®, was present in the blood. Murine hearts were exposed for 5 min at either 1.15 or 2.35 MHz with a pulse length of 10 μs and pulse repetition frequency of 100 Hz. During the exposure period, four boluses of Albunex ® were injected into a tail vein for a total of ∼ 0.1 mL of Albunex ®. Following exposure, blood was collected by heart puncture and centrifuged, and the plasma was analyzed for hemoglobin concentration. With Albunex ® present in the blood, the threshold for hemolysis at 1.15 MHz was 3.0 ± 0.8 MPa (mean ± SD) peak positive pressure (∼ 1.9 MPa negative pressure, ∼ 180 W cm −2 pulse average intensity). For the highest exposure levels (10 MPa peak positive pressure at the surface of the animal), the mean value for hemolysis was ∼ 4% at 1.15 MHz and 0.46% at 2.35 MHz, i.e., the threshold at 2.35 MHz is >10 MPa peak positive pressure. In contrast, hemolysis in control mice receiving saline injections at 10 MPa or sham-exposed (0 MPa) mice receiving Albunex ® was ∼ 0.4%.