Subclinical Intra-Aortic Thrombus Associated With Impella CP Device　― Consideration of Anatomic Characteristics ―

A 59-year-old male presented with myocardial infarction and cardiogenic shock. Coronary angiography confirmed 3-vessel stenosis including left anterior descending occlusion. An Impella CP (Abiomed Inc., MA, USA) was inserted via the right femoral artery and a percutaneous coronary intervention (PCI) was performed. The patient was administered unfractionated heparin (UFH) in dextrose 5% purge solution at 40 IU/h and systemic anticoagulation was titrated to maintain the activated clotting time between 160 and 180 s. As post-PCI antiplatelet therapy, aspirin 100 mg/day and prasugrel 3.75 mg/day was prescribed.

The Impella was removed surgically on day 5 (total usage time: 99 h), and a pearly-white cylindrical-shaped substance was also extracted (Figure A). Transesophageal echocardiography (TEE) after Impella retraction revealed cylindrical-shaped objects (29 mm diameter) in the distal end of the aortic arch and in the ascending aorta, which were suspected to be remains of the thrombi that had formed around the Impella shaft (Figure B). The extracted substance was pathologically confirmed as a mixture of red and white thrombi. UFH was continued and TEE on day 8 confirmed regression of the thrombi. On a comparative computer tomography (CT) scan, thrombi had formed where the Impella and aortic walls were in contact (Figure C). No further adverse events occurred and the patient was discharged on day 27.

Figure.

(A) Cylindrical-shaped thrombus retrieved together with Impella. (B) Intra-aortic thrombus from aortic arch to descending thoracic aorta (near arrowheads 2 in C) confirmed by transesophageal echocardiography (TEE). (C) CT scan shows the Impella in contact with the ascending aorta, aortic arch, and descending thoracic aorta (arrowheads 1 and 2 [upper and lower]). TEE confirmed thrombi at these locations.

This case suggests a location of Impella-related thrombi, and we speculate that contact between the Impella and the aortic wall might have contributed to their formation. In a retrospective single-center study, thromboembolic events, including subclinical findings, occurred in 36.4% of patients;¹ however, there are scarce reports regarding location. To confirm the cause of Impella-related thrombi, compiling larger numbers of cases is necessary, and multiple criteria, including patients’ physique, tortuosity and atherosclerotic changes of the aorta, should be evaluated.

Reference

• 1.   Takahashi K, Kubo S, Ikuta A, Osakada K, Takamatsu M, Taguchi Y, et al. Incidence, predictors, and clinical outcomes of mechanical circulatory support-related complications in patients with cardiogenic shock. J Cardiol 2022; 79: 163–169.