Hello, and welcome to the April 2018 edition of Vascular Disease Management. I have chosen to comment on Dr Noah Jone’s article on the use of acoustic pulsed thrombolysis (APT) in the treatment of acute life-threatening pulmonary embolization. In this article, Dr Jones describes the technique involved in the utilization of the EKOS device, which uses high-energy ultrasonic acoustic waves coupled with a short infusion of tissue plasminogen activator (tPA) to facilitate more rapid thrombolysis and reversal of adverse hemodynamic parameters than a typical standard infusion of tPA.
Dr Jones precisely describes which patients represent “high risk” and are the best candidates for early interventional rescue therapy. He describes in detail the steps involved with the EKOS device to treat massive pulmonary embolus when there is hemodynamic compromise. Potential benefits include less risk of bleeding, a much shorter observation period, prompt improvement in hemodynamic parameters, and potentially less bleeding related to the shorter duration of lytic infusion.
The EKOS device couples a side hole infusion catheter of up to 50 cm of treatment length and up to 135 cm of delivery length with a central ultrasonic catheter that delivers high frequency acoustic waves to thin out fibrin strands, allowing tPA penetration to the plasminogen activator sites. In theory, this facilitates better clot-drug interface and helps to mechanically disrupt fibrin strands.
Dr Jones describes the protocol that was utilized in the OPTALYSE PE trial. This trial resulted in similar results with a shorter treatment time frame and less total dosage of tPA than in the SEATTLE II study, in which a prolonged infusion of a higher dose of tPA was utilized.
This article is of great significance simply in treating the hemodynamic complications of massive pulmonary embolus, but the overall implications of this therapy are far greater. The thought that one can effectively remove thrombus with shorter lytic infusions with less total dosage of infused thrombolytic agent is appealing in the treatment of acute and chronic thrombus in vital arterial and venous segments throughout the body. Despite multiple articles detailing the benefits of lytic therapy in treating patients with a wide variety of arterial and venous obstructions caused by acute or chronic clot, physicians are wary of potential bleeding complications. Physicians are also wary of hemolysis that is seen with some of the other mechanical thrombectomy devices.
Although most complications associated with lytic infusion are minor, some, particularly intracranial hemorrhage and retroperitoneal bleeds, are life threatening. Even though most serious bleeding occurs in high-risk patients who fit profiles that can be identified a priori, occasionally severe and even fatal bleeds may occur in patients who are deemed to be at low risk for thrombolytic infusion.
Obviously, if effective thrombolysis can be accomplished in a shorter time frame with less overall dosage of thrombolytic agent, it would seem probable that this would diminish the risk of pathological bleeding and encourage greater utilization.
Thrombus plays a vital role in the majority of ischemic cardiovascular syndromes. It is the culminating factor in most acute ischemic events. Clinicians need more effective, more rapid, and safer ways to remove life-threatening thrombus. This report by Dr Jones is encouraging in that it suggests that the EKOS device may deliver those attributes in the treatment of massive pulmonary embolus where there is hemodynamic compromise. One must question how many other arterial and venous beds may benefit from the utilization of this device coupled with a shorter thrombolytic infusion.