Endovascular Management of Massive Sub-Massive Pulmonary Embolism

Venous thromboembolism (VTE) comprises of two closely related disease entities: deep vein thrombosis (DVT) and pulmonary embolism (PE). In one third of patients venous thrombosis is accompanied by symptomatic PE. Risk of PE is relatively high in patients with advanced chronic diseases, such as malignancies. Most cancer patients have blood coagulation abnormalities leading to VTE. The mortality in untreated PE is high (30%) but appropriate treatment may decrease it to 2–18%. CT Pulmonary Angiography (CTPA) is the modality of choice for diagnosing and stratifying such patients. PE has classically been divided into “massive,” “submassive,” and “low-risk” categories and Interventional radiology plays a vital role in the management of both massive and submassive PE.

Massive PE is defined as acute PE with hemodynamic changes, including sustained hypotension (systolic blood pressure <90 mm Hg for a minimum of 15 minutes or requiring inotropic support), pulselessness, or continued bradycardia (heart rate <40 bpm with signs or symptoms of shock). Submassive PE is defined as acute PE with evidence of right heart strain or myocardial necrosis but without sustained hypotension (systolic blood pressure ≥ 90 mm Hg);

In the absence of any contraindications, all patients with acute PE should receive prompt initiation of appropriate anticoagulation therapy.

SYSTEMIC THROMBOLYSIS

Parenteral systemic thrombolytic agents may be indicated in patients who require more aggressive therapy than anticoagulation alone. Given the risk–benefit balance of systemic thrombolysis, careful selection of candidates for thrombolysis is crucial. Contraindications to thrombolytic therapy include recent cerebrovascular accident, intracranial trauma or surgery within the last 2 months, active intracranial disease, or recent major surgery, among many others

CATHETER – DIRECTED THERAPY (CDT) 

The American Heart Association (AHA), European Society of Cardiology (ESC), and American College of Chest Physicians (ACCP) guidelines recommend consideration of CDT for massive and sub massive PE in cases for which systemic thrombolysis is contraindicated or has failed. CDT includes several techniques such as mechanical and aspiration thrombectomy, catheter-directed thrombolysis, ultrasound accelerated thrombolysis. CDT has the benefit of using lower thrombolytic doses and direct intraclot administration of thrombolytic therapy.

In the setting of massive PE, there may be insufficient time or additional co-morbidities which preclude the systemic thrombolysis. In such settings, CDT can be used as a first-line treatment option. CDT therapy can achieve more rapid lysis while reducing the overall thrombolytic drug dose. While systemic thrombolysis uses 100 mg of tPA infused over 2 hours, CDT uses infusion rates of 1 to 2 mg tPA per hour for a total dose of < 30 mg. CDT has the potential to provide the benefits of thrombolysis while decreasing the risk of major bleeding. It also allows for direct measurement of PA pressures and CO, providing an objective assessment of hemodynamic response to treatment.
We share our experience with two such patients who presented with sub-massive PE and were admitted in the Intensive Care Unit of our hospital and were treated successfully with CDT.

Case No. 1

A 68 year old lady being treated for MUO (Adenocarcinoma) on palliative chemotherapy developed sudden onset breathlessness and found to have sub-massive PE with right heart strain. We performed catheter directed thrombolysis with direct infusion of t-PA into the thrombus in both pulmonary arteries and the patient was shifted out of the ICU the next day of completing the thrombolysis with complete resolution of right heart strain.