Optimum Duration of Acoustic Pulse Thrombolysis Procedure in Acute Pulmonary Embolism

This study is designed to investigate the lowest recombinant tissue plasminogen activator (r-tPA) dose-ultrasound treatment time required to achieve the same reductions in thrombus burden and associated improvement in physiologic parameters demonstrated in ULTIMA (EKOS 08 \[NCT01166997\]) and SEATTLE II (EKOS 09 \[NCT01513759\]). Results of this study are intended to inform the study design for further studies of the Acoustic Pulse Thrombolysis (APT) Procedure. Analysis of the first 100 evaluable participants in the United States study suggested a degree of equipoise between treatment groups 1, 2 and 3 of the protocol and therefore the sample size has been extended and additional sites in the United Kingdom (UK) National Health Service included, with a view to adding to the findings of the OPTALYSE study from sites in the UK and increasing the number of participants treated by treatment protocol.