Floating Clots in the Descending Aorta Associated With the Impella Cardiac Power: Importance of Transoesophageal Echocardiography.

Ventricular septal defect (VSD) is a lethal complication of acute myocardial infarction that presents with rapid clinical deterioration due to acute heart failure and cardiogenic shock.1Ibanez B James S Agewall S et al.2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC).Eur Heart J. 2018; 39: 119-177Crossref PubMed Scopus (5835) Google Scholar Impella CP (Cardiac Power; Abiomed, Inc, Danvers, MA) support improves the hemodynamic and end-organ function and may improve the surgical outcomes for patients with cardiogenic shock due to VSD after acute myocardial infarction.2Saito S Shibasaki I Matsuoka T et al.Impella support as a bridge to heart surgery in patients with cardiogenic shock.Interact Cardiovasc Thorac Surg. 2022; 35 (ivac088)Crossref Scopus (3) Google Scholar,3Ancona MB Regazzoli D Mangieri A et al.Post-infarct ventricular septal rupture: Early Impella implantation to delay surgery and reduce surgical risk.Cardiovasc Interv Ther. 2017; 32: 381-385Crossref PubMed Scopus (11) Google Scholar The incidence of thrombotic complications with Impella has been reported to be 0.7% in the Japanese registry.4Ikeda Y Ako J Toda K et al.Short-term outcomes of Impella support in Japanese patients with cardiogenic shock due to acute myocardial infarction—Japanese Registry for Percutaneous Ventricular Assist Device (J-PVAD).Circ J. 2023; 87: 588-597Crossref PubMed Scopus (2) Google Scholar However, the true incidence of thrombotic complications in patients with Impella CP can be underestimated or underrecognized, given this cohort's extremely high baseline mortality and morbidity. Herein, we report a rare case of a massive thrombus floating along the Impella CP device in the descending aorta despite administering adequate anticoagulant therapy. In our case report, perioperative transesophageal echocardiography (TEE) was useful for the designation and optimal management of the treatment strategy. A 68-year-old male (height, 1.68 m; weight, 45.5 kg) with dyspnea was diagnosed with acute coronary syndrome and transferred to our hospital. His coagulation status on admission was as follows: international normalized ratio (INR), 1.7; activated partial thromboplastin time (aPTT), 37.8 seconds; fibrinogen level, 396 mg/dL; D-dimer, 6.14 µg/mL; and platelet count, 326 × 103/μL. His peak troponin I level was 3,932 ng/mL, and he was in a state of shock. He was intubated, and an intra-aortic balloon pump was placed via his left femoral artery. Emergency coronary angiography revealed significant stenosis in the left anterior descending artery, and left ventriculography confirmed the presence of a VSD. The primary percutaneous coronary intervention was performed using a drug-eluting stent. After the procedure, the intra-aortic balloon pump was replaced with the Impella CP device via the right femoral artery with a flow rate of 3.0 L/min. Unfractionated heparin was administered to maintain an activated clotting time (ACT) of 152 to 229 seconds and aPTT of 76 to 166 seconds. Subsequently, aspirin and clopidogrel were administered. On day 2, the patient was transferred to the operating room for surgical VSD repair. His preoperative coagulation status was as follows: INR, 1.7; aPTT, 166 seconds; fibrinogen level, 252 mg/dL; and platelet count, 165 × 103/μL. Anesthesia induction was uneventful, and a TEE probe was inserted, which showed a huge mobile thrombus extending along the distal aortic arch to the distal descending aorta (Fig 1, A and B, and Supplementary Video S1). The thrombus in the descending aorta extended as far as it could be observed on TEE. The maximum size of the thrombus in the short-axis view of the TEE was 13 × 18 mm. Additional TEE findings included a left-to-right shunt in the left ventricle and severe wall motion abnormalities in the anteroseptal to lateral walls. Heparin was administered during the cardiopulmonary bypass (CPB) procedure to maintain the value of ACT >400 seconds. VSD closure was performed using the extended sandwich patch technique via right ventriculotomy.5Kinoshita T Asai T Hachiro K et al.Extended sandwich patch technique via right ventriculotomy for acute ventricular septal rupture.Ann Thorac Surg. 2022; 113: 1200-1207Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar After the procedure, the patient was weaned from CPB, although the Impella CP was still necessary to maintain the hemodynamics. The thrombus in the descending aorta was unaltered after the CPB. In the intensive care unit (ICU), the Impella CP flow rate was maintained at 2.2 to 3.0 L/min. Heparin was administered as an anticoagulant therapy, targeting an ACT of 180 to 210 seconds. Aspirin and clopidogrel were discontinued. His coagulation status on ICU admission was as follows: INR, 1.4; aPTT, 53 seconds; fibrinogen level, 171 mg/dL; D-dimer, 5.64 µg/mL; and platelet count, 173 × 103/μL. Two days after the surgery, a computed tomography (CT) scan showed a thrombus formation around the shaft of the Impella CP (Supplementary Fig S1). His first-measured antithrombin III concentration after admission on that day was 62%. As the patient's hemodynamics stabilized, removal of the Impella CP was planned for 4 days after the initial surgery. Although the intraoperative TEE showed that the thrombus was smaller than at the time of the initial surgery, it was still present and mobile (Fig 1C and Supplementary Video S2). The thrombus extended along the distal aortic arch to the distal descending aorta as during the initial surgery. The maximum size of the thrombus in the short-axis view of the TEE was 10 × 18 mm. Impella CP was removed after confirming an ACT value >180 seconds. The femoral artery on the peripheral side of Impella insertion and the bilateral common carotid arteries were compressed until the cerebral oximetry INVOS 5100 (Medtronic, Inc, Minneapolis, MN) value showed a decrease while the Impella CP was removed. The TEE revealed a residual mobile thrombus (Fig 1D and Supplementary Video S3). After removal, the patient was continued on anticoagulant therapy with heparin and was extubated on postoperative day 8. Warfarin, aspirin, and clopidogrel were administered on postoperative day 8. No obvious embolic or neurologic complications were observed in the perioperative period. The patient was discharged from the ICU on postoperative day 24. The descending thrombus disappeared on contrast-enhanced CT on postoperative day 57 (Supplementary Fig S2). In our case, intraoperative TEE revealed a rare Impella-associated thrombus. Previous reports suggest that contrast-enhanced CT and angiography are useful in the diagnosis of the thrombus2Saito S Shibasaki I Matsuoka T et al.Impella support as a bridge to heart surgery in patients with cardiogenic shock.Interact Cardiovasc Thorac Surg. 2022; 35 (ivac088)Crossref Scopus (3) Google Scholar,6Degrauwe S Iglesias JF Glauser F et al.Successful percutaneous mechanical thrombectomy of an Impella CP-related femoral artery thrombosis.Cardiol J. 2021; 28: 185-186Crossref PubMed Scopus (0) Google Scholar; however, in severe conditions requiring Impella placement, it is difficult to perform these modalities. Thrombosis associated with Impella can cause sudden organ failure, leading to an awful outcome.7Yamana F, Domae K, Kawasumi R, et al. Aortic thrombosis with visceral malperfusion during circulatory support with a combination of Impella and extracorporeal membrane oxygenation for postcardiotomy cardiogenic shock [e-pub ahead of print]. J Artif Organs. https://doi.org/10.1007/s10047-023-01382-3. Accessed May 18, 2023.Google Scholar Contrary to CT and fluoroscopy, TEE can be performed in the operating room or at the bedside. Perioperative TEE is useful in the perioperative management of the Impella to detect and manage thrombotic complications such as the present case. The literature provides minimal guidance on anticoagulation therapy, and the thromboembolic risks associated with the use of Impella CP may be attributable to the complexity and relative lack of evidence-based Impella-related anticoagulation practices.8Beavers CJ DiDomenico RJ Dunn SP et al.Optimizing anticoagulation for patients receiving Impella support.Pharmacother J Hum Pharmacol Drug Ther. 2021; 41: 932-942Crossref PubMed Scopus (0) Google Scholar,9Reed BN DiDomenico RJ Allender JE et al.Survey of anticoagulation practices with the impella percutaneous ventricular assist device at high-volume centers.J Intervent Cardiol. 2019; 2019: 1-6Crossref Scopus (22) Google Scholar It is possible that the ACT was shortened when unmonitored, although our institutional anticoagulation management does not differ significantly from the manufacturer's recommendations (the goal of ACT is 160-180 seconds).8Beavers CJ DiDomenico RJ Dunn SP et al.Optimizing anticoagulation for patients receiving Impella support.Pharmacother J Hum Pharmacol Drug Ther. 2021; 41: 932-942Crossref PubMed Scopus (0) Google Scholar,9Reed BN DiDomenico RJ Allender JE et al.Survey of anticoagulation practices with the impella percutaneous ventricular assist device at high-volume centers.J Intervent Cardiol. 2019; 2019: 1-6Crossref Scopus (22) Google Scholar Although the target ACT range was achieved, the patient's low antithrombin III level might also have contributed to this thrombotic complication. The P2Y12 platelet response assay was not conducted in the present case. Along with the preoperative assessment of coagulation and potential thrombotic status, the P2Y12 platelet response assay could have been performed to confirm the patient's response to clopidogrel. The floating descending thrombus was detected accidentally by TEE on the second day after Impella CP implantation. So far, only 3 case reports have described patients with Impella CP who were diagnosed with aortic thrombosis.2Saito S Shibasaki I Matsuoka T et al.Impella support as a bridge to heart surgery in patients with cardiogenic shock.Interact Cardiovasc Thorac Surg. 2022; 35 (ivac088)Crossref Scopus (3) Google Scholar,6Degrauwe S Iglesias JF Glauser F et al.Successful percutaneous mechanical thrombectomy of an Impella CP-related femoral artery thrombosis.Cardiol J. 2021; 28: 185-186Crossref PubMed Scopus (0) Google Scholar,10Ando M Garan AR Axom KM et al.Floating clots in the descending aorta: A rare complication of femoral venoarterial extracorporeal membrane oxygenation combined with microaxial pump for cardiogenic shock.Circ Heart Fail. 2017; 10e004196Crossref PubMed Scopus (1) Google Scholar Ando et al. reported a case of floating clots in the descending aorta in a patient who was on femoral venoarterial extracorporeal membrane oxygenation with Impella for cardiogenic shock despite adequate anticoagulation.10Ando M Garan AR Axom KM et al.Floating clots in the descending aorta: A rare complication of femoral venoarterial extracorporeal membrane oxygenation combined with microaxial pump for cardiogenic shock.Circ Heart Fail. 2017; 10e004196Crossref PubMed Scopus (1) Google Scholar In the case, systemic anticoagulation with aPTT of 80 seconds and antiplatelet therapy were administered. However, as in our case, on the second day after Impella placement, a huge mobile thrombus was revealed in the descending aorta on intraoperative TEE. The authors noted that simultaneous support by femoral venoarterial extracorporeal membrane oxygenation and the Impella device could cause thrombus formation in the descending aorta because of blood stasis, even with appropriate anticoagulation therapy. Sophie et al. reported thrombosis associated with Impella CP use, although the details of anticoagulation were unknown.6Degrauwe S Iglesias JF Glauser F et al.Successful percutaneous mechanical thrombectomy of an Impella CP-related femoral artery thrombosis.Cardiol J. 2021; 28: 185-186Crossref PubMed Scopus (0) Google Scholar In their case, angiography at the time of Impella removal 3 days after implantation revealed a thrombosis extending on the entire length of the common femoral artery and the distal external iliac artery. Mechanical thrombectomy, anticoagulation, and Impella removal are the main treatment options for thrombosis associated with the Impella.6Degrauwe S Iglesias JF Glauser F et al.Successful percutaneous mechanical thrombectomy of an Impella CP-related femoral artery thrombosis.Cardiol J. 2021; 28: 185-186Crossref PubMed Scopus (0) Google Scholar,10Ando M Garan AR Axom KM et al.Floating clots in the descending aorta: A rare complication of femoral venoarterial extracorporeal membrane oxygenation combined with microaxial pump for cardiogenic shock.Circ Heart Fail. 2017; 10e004196Crossref PubMed Scopus (1) Google Scholar Although the clot remained, we removed the Impella because the patient's hemodynamic condition had improved. Blind catheter removal of a descending aortic thrombus carries a high risk of embolic stroke. Direct surgical removal of descending aortic thrombus is too invasive to the patient. The thrombus, in this case, was not chronic. Therefore, we decided to remove the Impella device and provide anticoagulation therapy. In the event of an embolism or enlargement of the thrombus, we would have removed the thrombus mechanically. The multidisciplinary team should decide on the Impella management strategy based on the risks of vascular occlusion, stroke, bleeding, and device-related infection and the benefits, such as facilitating rehabilitation. Adequate anticoagulation of a patient with an Impella is difficult to determine, lacks consistency across centers, and is a challenging aspect of critical care.8Beavers CJ DiDomenico RJ Dunn SP et al.Optimizing anticoagulation for patients receiving Impella support.Pharmacother J Hum Pharmacol Drug Ther. 2021; 41: 932-942Crossref PubMed Scopus (0) Google Scholar,9Reed BN DiDomenico RJ Allender JE et al.Survey of anticoagulation practices with the impella percutaneous ventricular assist device at high-volume centers.J Intervent Cardiol. 2019; 2019: 1-6Crossref Scopus (22) Google Scholar,11Succar L Sulaica EM Donahue KR et al.Management of anticoagulation with Impella percutaneous ventricular assist devices and review of new literature.J Thromb Thrombolysis. 2019; 48: 284-291Crossref PubMed Scopus (25) Google Scholar Further research is warranted to guide anticoagulation management during Impella placement. In the present case, we experienced a rare case of massive thrombus formation along the Impella CP device in the descending aorta. In patients with Impella CP placement due to cardiogenic shock, thrombus formation in the descending aorta should be kept in mind even with appropriate anticoagulation therapy, and perioperative TEE should be useful for diagnosis and therapeutic decision-making. 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