Veno-Arterial Extracorporeal Membrane Oxygenation as a Salvage Therapy in Massive Pulmonary Embolis

Abstract

INTRODUCTION: Cardiogenic shock from pulmonary embolism (PE) is often fatal. Therapies include systemic thrombolysis, catheter thrombolysis, surgical embolectomy, and catheter embolectomy. Extracorporeal membrane oxygenation (ECMO) has sporadically been used in treating hemodynamically significant PE. We report the case of a 38 year-old man with PE and refractory shock after systemic thrombolysis who was supported with veno-arterial (VA) ECMO with hemodynamic improvement. This case demonstrates the successful use of ECMO in massive PE with refractory shock after systemic thrombolysis. CASE PRESENTATION: A 38 year-old man presented to the hospital with bilateral leg pain and dyspnea. Three years prior he had deep venous thrombosis (DVT) following knee arthroscopy, treated with surgical thrombectomy and systemic anticoagulation. An inferior vena cava (IVC) filter was placed. For one year he had not taken systemic anticoagulation. His mother and brother had a history of DVT. Physical examination revealed a man in no distress with normal vital signs and bilateral lower extremity edema. Lower extremity ultrasound revealed acute DVT in the right common femoral and left common iliac veins. Abdominal computed tomography (CT) demonstrated clot extending through the IVC filter. Chest CT demonstrated filling defects in the distal right main pulmonary artery and left lower lobe pulmonary artery. Transthoracic echocardiography revealed mild right ventricular dysfunction. Electrocardiogram, troponin, and pro-brain natriuretic peptide were normal. The patient received heparin infusion and underwent pharmacomechanical thrombectomy of the IVC DVT. The following day he suffered acute respiratory failure and shock while ambulating. Despite mechanical ventilation with an FiO2 of 1.0, fluid resuscitation, and vasopressor support, he did not improve. Transthoracic echocardiography demonstrated acute pulmonary hypertension, severe right ventricular dilatation and hypokinesis but preserved contractility of the apex. He received alteplase 100 mg intravenously for presumed massive PE, but remained hypotensive four hours later. VA ECMO was instituted through an 8mm Gelweave graft sewn to the femoral artery and a 22Fr vacuum assist cannula passed into the right atrium via the femoral artery. Bleeding at cannulae sites due to recent thrombolysis and anticoagulation necessitated multiple transfusions. After 24 hours, transesophageal echocardiography showed improved right ventricular function, and ECMO was discontinued. The patient recovered fully and was discharged on low molecular weight heparin. Thrombophilia workup was unrevealing. DISCUSSION: Mortality from cardiogenic shock after a massive PE approaches 75%. (1) Anticoagulation, which relies on intrinsic fibrinolysis, might not restore systemic circulation quickly. Case reports and series have explored ECMO as a means of unloading the right ventricle and supporting systemic circulation in massive PE. ECMO has been utilized mainly in patients with contraindications to other interventions or as a bridge when profound shock precluded their immediate use. Fewer reports describe ECMO in patients with refractory shock after treatment.(1-3) Our case demonstrates the use of ECMO in a patient with massive PE and refractory shock despite systemic thrombolysis. ECMO allowed our patient time in which right ventricular function recovered and shock reversed. This case illustrates ECMO as a feasible salvage therapy in massive PE with refractory shock after treatment. CONCLUSIONS: ECMO should be considered for the treatment of PE with refractory cardiogenic shock after systemic thrombolysis.