Development of forward-looking ultrasound transducers for microbubble-aided intravascular ultrasound-enhanced thrombolysis

Pulmonary embolism (PE) is the third-leading cause of death from cardiovascular disease. Currently, PE is treated via catheter-delivered, ultrasound-enhanced thrombolysis using side-fired, low-intensity ultrasound energy (0.5 W/cm²) at ∼2 MHz to reduce the required dose of thrombolytic drugs because of the enhanced drug penetration into the clot. However, several clinical studies have shown that the relatively high-frequency (2 MHz), low-power ultrasound is insufficient for improving thrombolytic efficacy. Low-frequency (< 1 MHz), higher intensity ultrasound yields a higher thrombolytic rate, however, the propagation of ultrasound toward the vessel wall (side looking) results in increased likelihood of healthy tissue damage from overexposure of acoustic energy. We hypothesize that a forward-looking intravascular ultrasound transducer design will enable generation of higher pressures at a lower operating frequency, which can enhance the lytic rate and reduce the required dose of the drug.