Travelling thrombus during interventional thrombectomy

A 56-year-old man presents to the ER with exertional dyspnea and sinus tachycardia. His HR is 120 bpm, BP is 132/98 mmHg, and oxygen sat. on room air is 94%. CT angiography reveals a central bilateral pulmonary embolism (see Fig. 1), involving all segmental arteries, as well as signs of right heart strain. Laboratory results show elevated cardiac enzymes (troponin 88 ng/l, NT-proBNP 8300 ng/l). The sPESI score is 1. We classified the patient as an intermediate-high risk patient and decided to proceed with an interventional thrombectomy due to the high NT-proBNP level, the massive thrombus and his symptoms. The procedure is performed through the right groin (common femoral vein). After ultrasound guided femoral puncture, a 6 Fr sheath and a Proglide system for preclosure were inserted, followed by advancing a pigtail catheter into the pulmonary arteries and displaying the right and left vascular anatomy and thrombus formation by angiography (see Fig. 2). A 24 Fr sheath was inserted and a FlowTriever catheter (INARI) initially placed in the left central pulmonary artery and confirmed under fluoroscopy. Thrombotic material is then retrieved through multiple aspirations with extractions of relevant amount of thrombus material (see Fig. 3). Heparin was administered after the initial puncture and the ACT remained above 300 seconds throughout the whole procedure. After extraction of all thrombotic material of the left pulmonary artery, the thrombectomy catheter was switched to the right central pulmonary artery. During the first thrombus aspiration on the right inferior lobar arteries of the pulmonary artery, no thrombus was able to be extracted (see Fig. 3). Due to good positioning of the catheter and known massive thrombus material, we suspected to have the thrombus in the catheter or sheath. Consequently, the catheter and sheath were externalized and flushed, but no thrombotic material was found. During this maneuver, the patient experienced worsening dyspnea, which was verified by a drop in oxygen saturation from 94% without oxygen to 88% on 4L of oxygen, along with a drop in blood pressure to 100/63 mmHg. We decided to continue to retrieve material from the right side, as angiography still showed a massive thrombus in the inferior and superior lobar arteries. After successfully extracting a large amount of thrombotic material from the right pulmonary artery, with a good angiographic result, we decided to perform another angiography of the left pulmonary artery. This revealed a new extensive thrombus in the left pulmonary artery (see Fig. 4), which had not been seen after the initial aspiration. After another aspiration of the thrombus material, the left side showed again a good angiographic result, with perfusion restored to all lobar arteries (see Fig. 4). Following complete aspiration, the patient's symptoms improved, and arterial saturation rose to 100%, allowing for the withdrawal of oxygen support. The blood pressure normalised to 135/75 mmHg. The procedure was then terminated and femoral access was closed with the Proglide system without any complications.
We suspect that during the externalization of the catheter and sheath, a large thrombus fragment may have embolised from the catheter and traveled to the left pulmonary artery.
During interventional thrombectomy with massive thrombus formation, a final angiogram of both pulmonary arteries seem reasonable in order to detect any travelling or procedure related embolised thrombi.