Endovascular therapies for pulmonary embolism

Abstract

Purpose: The aim of this article is to define the place of new endovascular methods for the management of pulmonary embolisms (PE), on the basis of a multidisciplinary consensus.

Method and results: Briefly, from the recent literature, for high-risk PE presenting with shock or cardiac arrest, systemic thrombolysis or embolectomy is recommended, while for lowrisk PE, anticoagulation alone is proposed. Normo-tense patients with PE but with biological or imaging signs of right heart dysfunction constitute a group known as "at intermediate risk" for which the therapeutic strategy remains controversial. In fact, some patients may require more aggressive treatment in addition to the anticoagulant treatment, because approximately 10% will decompensate hemodynamically with a high risk of mortality. Systemic thrombolysis may be an option, but with hemorrhagic risks, particularly intra cranial. Various hybrid pharmacomechanical approaches are proposed to maintain the benefits of thrombolysis while reducing its risks, but the overall clinical experience of these different techniques remains limited. Patients with high intermediate and high risk pulmonary embolism should be managed by a multidisciplinary team combining the skills of cardiologists, resuscitators, pneumologists, interventional radiologists and cardiac surgeons. Such a team can determine which intervention - thrombolysis alone or assisted, percutaneous mechanical fragmentation of the thrombus or surgical embolectomy - is best suited to a particular patient.

Conclusions: This consensus document define the place of endovascular thrombectomy based on an appropriate risk stratification of PE.

Keywords: Embolectomy; Pharmacomechanical thrombectomy; Pulmonary embolism; Thrombectomy; Thrombolytic therapy.

Figure 1

Risk stratification in PE. Patients with PE are classified according to haemodynamic consequences, biomarker levels and imaging findings. High-risk patients have acute haemodynamic failure, including cardiac arrest and cardiogenic shock. Patients with paradoxical bradycardia, ventricular tachycardia and relative hypotension (systolic blood pressure <90 mmHg) are included in this group. Normotensive patients with elevated cardiac biomarkers (troponin and natriuretic peptides) or CT/ultrasound evidence of right ventricular strain (dilation, interventricular septum bulging or right ventricular systolic dysfunction) are assigned to the intermediate-risk group. The low-risk group comprises patients without haemodynamic instability, with normal levels of RV strain biomarkers and low prognostic index scores (simplified pulmonary embolism severity index, sPESI).

Figure 2

Multihole infusion catheter (AngioDynamics, Inc.). Multihole infusion catheter with side holes for delivery of fibrinolytics within the thrombus using a simple wire that occludes the tip of the catheter in order to deliver the fluid through the side holes.

Figure 3

Ekos system. The Ekos system consists of a multihole infusion catheter, an ultrasonic core and a control unit (Ekos Corp.).

Figure 4

AngioVac catheter (AngioDynamics) removes thrombi by pumping and filtering the patient's blood and then reinfusing it via a reperfusion circuit. This large-bore device is designed to be inserted via the femoral vein and used for removal by aspiration of large thrombi from the pulmonary arteries. The funnel-shaped balloon on its distal tip is used to occlude the vein in which it is placed.

Figure 5

Penumbra INDIGO system (Penumbra Inc.): Penumbra's Indigo CAT 8 system is a flexible 8 F aspiration catheter connected to a continuous vacuum system. The catheter's lumen contains a wire with an olive-shaped distal tip that enhances clot fragmentation and recovery.

Figure 6

The FlowTriever device (Inari Medical) has 3 nitinol mesh disks that deploy into the thrombus and draw it into the catheter by manual aspiration.

Figure 7

ASPIREX (Straub). Catheter with a worm screw beneath a side opening at its distal end. Thrombectomy is achieved by rotating the screw which draws the thrombus into the catheter.

Figure 8

AngioJet rheolytic thrombectomy (Boston Scientific). Pressure-pulsed delivery of saline at the catheter's distal tip fragments the thrombus and creates a Venturi effect that aspirates and removes the fragments via a second lumen.