Pulmonary embolism: catheter thrombectomy with FlowTriever (Inari) and Lightning (Penumbra) devices

What a pulmonary embolism is

A pulmonary embolism is usually a blood clot that travels from a leg or pelvic vein (see the deep vein thrombosis guide) to the arteries in the lungs. It strains the right side of the heart and reduces oxygen. It is grouped by severity: low-risk, intermediate-risk (stable, but with strain on the right heart), and high-risk (low blood pressure or shock). Treatment depends on this grade.

Usual treatment, and where catheters fit

Anticoagulant (blood-thinning) medicine is the foundation. For high-risk PE, clot-dissolving drugs given into a vein are the standard. The 2019 European guideline discusses catheter-directed treatment, either clot-dissolving drugs through a catheter or mechanical removal, for selected patients, particularly high-risk PE when thrombolysis has failed or cannot be used ^[1]. A pulmonary embolism response team, with a chest physician, cardiologist, intensivist and interventional radiologist, usually decides.

How large-bore thrombectomy works

These devices physically remove the clot instead of dissolving it.

• A sheath is placed in a large vein, usually at the groin, under local anaesthetic.
• A large catheter is guided through the right side of the heart into the lung arteries under X-ray.
• The clot is sucked out through the catheter, using a syringe or a continuous suction device. Examples are the FlowTriever system (Inari) and the Lightning or Indigo systems (Penumbra).
• Blood pressures and oxygen levels are monitored, and repeat imaging confirms clot removal.
• Blood thinners continue afterwards, and recovery is monitored in a high-dependency or intensive care unit.

What the studies show

In the FLARE single-arm trial, 106 patients with intermediate-risk PE had thrombectomy with the FlowTriever system. The right-to-left ventricle ratio fell by an average of 0.38 (25.1%) within 48 hours, and 41.3% needed no intensive care stay ^[2]. In the EXTRACT-PE single-arm trial, 119 patients treated with the Indigo system had a mean reduction in that ratio of 0.43, and thrombolytic drugs were avoided in 98.3% ^[3]. In the PEERLESS randomised trial, large-bore thrombectomy was compared with catheter-directed thrombolysis in intermediate-risk PE. Thrombectomy had fewer clinical deterioration events, less postprocedural intensive care use, shorter hospital stays and fewer readmissions, while deaths and major bleeding were similar ^[4].

Limits of the evidence

These trials mostly measure how much the strain on the heart improves and short-term safety. FLARE and EXTRACT-PE had no control group, and PEERLESS compared two catheter strategies, so none has shown that thrombectomy saves more lives than blood thinners alone. Trials are continuing. Large devices are not suited to every patient or lesion, for example very small branch clots or some anatomies. Device companies funded much of this research, which is why independent guidelines ^[1] and a multidisciplinary decision matter.

Risks

Risks include bleeding, injury to the heart or a lung artery, an abnormal heart rhythm, kidney injury from contrast dye, a drop in blood pressure during the procedure, and access site problems. Because the patient is often already unwell, thrombectomy is done in a hospital with intensive care, in a team that can handle these events.

Preventing another clot

The source clot, often in the legs, needs attention, and blood thinners usually continue for months. For patients who cannot take blood thinners, a vena cava filter is sometimes used. Your doctors also look for the cause, such as recent surgery, immobility, cancer or a clotting disorder.

Cost and insurance

Health insurance can cover these procedures, subject to your policy terms. The cost depends on the hospital, the devices used and the length of stay, and is explained once the plan is made after consultation and a review of your scans. Cashless treatment can be arranged with major Indian health insurers and TPAs, and credit treatment is available for CGHS and Singareni beneficiaries. Eligibility is confirmed after a policy check.