Catheter-Directed Thrombolysis With Ultrasound Assistance for Acute Pulmonary Embolism

Abstract

Acute pulmonary embolism (PE) is the third leading cause of cardiovascular mortality in the United States after myocardial infarction and stroke. 1-4 Accordingly, over the last decade, there has been an increasing focus on in-hospital and ambulatory treatment of PE. Specifically, novel multidisciplinary efforts such as Pulmonary Embolism Response Teams have proliferated throughout many tertiary and quaternary care institutions across the country and are focused on optimizing the care of patients presenting with intermediate and high-risk PE. These teams now have access to a wide variety of US Food and Drug Administration 510(k)-cleared devices (nine to be exact) to treat PE from an interventional perspective. 5One increasingly used modality for the treatment of intermediate-high and high-risk PE is infusion of a thrombolytic agent via a catheter inserted into the pulmonary artery (known as catheter-directed thrombolysis [CDT]). 5,6 One device, the 5F catheterbased EkoSonic endovascular system (EKOS Corporation), is cleared by the US Food and Drug Administration for acute PE therapy and is an ultrasound-assisted thrombolytic (CDT-US) alternative to simple delivery of thrombolytic agents via a multi-holed infusion catheter. The addition of focused ultrasound energy to traditional CDT aims to disrupt thrombus ultrastructure, allowing for more effective penetration of thrombolytic molecules into a thrombus. This method theoretically could lead to more effective clot resolution, perhaps at lower doses than would otherwise be used with traditional CDT. 7 The evidence supporting the use of CDT-US over traditional CDT is currently limited by a lack of prospective, comparative clinical (as opposed to imaging) outcomes data. Studies comparing the two approaches to date have been single-center, retrospective, and modest in scope, with a focus on surrogate imaging outcomes related to echocardiographic comparisons of right ventricular function and pulmonary artery pressure changes. 8,9