Rotational intravascular multi-direction ultrasound transducer for sonothrombolysis of retracted clots

Venous thromboembolism (VTE) has emerged as a prominent contributor to global mortality rates. Recent advancements in intravascular sonothrombolysis technologies have demonstrated the potential for secure and efficient dissolution of clots within deep veins. However, current forward-viewing intravascular sonothrombolysis techniques exhibited limitations such as small channel size and the presence of large residual clots. Therefore, in this work, we developed a multi-directional miniaturized ultrasound transducer with a resonance frequency at 520 kHz. Under 80 V_pp input, the transducer reached a high peak negative pressure (PNP) of 4.9 MPa and 3.2 MPa with the forward- and side-looking elements, respectively. The multi-directional transducer was integrated with a 10-Fr shaft and controlled by a step motor for rotational intravascular sonothrombolysis. The ND-mediated sonothrombolysis was demonstrated in a flow model with 7-day retracted clot in-vitro. The rotational treatment showed a significant mass reduction of 53% after 30 min with a 37% higher lysis rate compared with the non-rotational forward-looking transducers.