Inclusion Criteria:

1. Patients aged >18 years old
2. Patients presenting a MPE (i.e. hemodynamically unstable at moment of the inclusion (i.e. shock index (SI) >1).

3. Patients where a hemodynamic stability (SI=1) is hardly obtained despite increasing dose of drug support.

   • If after 2 hours from the first medical contact where an intensive fluid substitution and cathecolamine support is begun the patient remains with a SI = 1, he/she could be included in the ART protocol.
   • If after an initial successful drug support (fluid + catecholamine) the patient represents a second episode of hemodynamic instability, he/she could be included in the ART protocol.
   • If the patient is under chronic negative chronotrope medication (e.g.beta-blockers) a SI = 1 will be sufficient to include the patient in the study
4. The MPE have to be confirmed by thorax CT-scan or suspected by echocardiography (i.e.visualized thrombus on the RV or main pulmonary trunk or RV overload with a high clinical suspicion of MPE).

Exclusion Criteria:

1. Very unstable patients with life threatening MPE where the time delays to transport them in the cathterization laboratory (i.e. <30 minutes) to perform the ART procedure is not acceptable because the systemic i.v. thrombolysis have to be immediately initiated in the emergency department.
2. Patients where a percutaneous right heart catheterization via the common femoral vein is contraindicated (e.g.vascular malformation, inferior cava vein occlusion, presence of bilateral ilio-femoral thrombosis, RV or pulmonary trunk malformation).
3. Patients with sub-MPE without any other clinical or para-clinical sign of severity (e.g. haemodynamically stable = SI<1).
4. Patients where the clinical evaluation estimated that the observed episode of MPE is older than 14 days (i.e. sub-acute phase with organized thrombus = ART less efficacious).
5. Patient with an estimated clearance to creatinine less than 30 ml/min.
6. Patients or members of their family who refused to give their signed informed consenstement.
7. Patient haemodynamically very unstable where the first clinical evaluation concludes that every therapeutic effort including the ART procedure or a systemic fibrinolysis will not change the short-term prognosis of the patient (i.e. imminent death).
8. Patients with a life expectancy of <3months for other medical pre-existing conditions.