An 84-year-old woman was brought to the emergency room with lightheadedness and shortness of breath that had started 3 days earlier. She had a past medical history of paroxysmal atrial fibrillation, hypertension, and coronary artery disease. She was not on anticoagulation due to medication non-compliance. On presentation, her vitals were: heart rate 150-200/min, blood pressure 129/99 mmHg, respiratory rate 19/min, and oxygen saturation on room air 99%. Physical exam was unremarkable. Electrocardiogram showed atrial fibrillation with rapid ventricular response at 189/min. Cardiac biomarkers were negative. She was initially treated with intravenous beta blockers and calcium blockers and due to inadequate response, urgent cardioversion with transesophageal echocardiography (TEE) was planned. TEE showed a large, mobile thrombus swirling in the right atrium (thrombus in transit) (Figure 1A). There was no left atrial appendage thrombus or interatrial shunt. As a result, cardioversion was postponed and she underwent emergent percutaneous mechanical thrombo-embolectomy with Inari FlowTriever 20 (Inari Medical) to aspirate thrombus from the right atrium under intra-cardiac echocardiography (ICE) guidance (Figure 1B). After one successful aspiration, ICE did not identify more thrombus in the right atrium and adjacent vena cava (Figure 1C). A serpentine thrombus was successfully aspirated (Figure 1D).
The patient was cardioverted back to sinus rhythm afterwards. Subsequent computed tomography (CT) pulmonary angiography revealed multiple bilateral pulmonary emboli involving bilateral lobar, segmental, and subsegmental branches along with bibasilar consolidative opacities concerning for pulmonary infarctions of the lower lobes. Lower extremity venous duplex ruled out deep vein thrombosis (DVT). Furthermore, an abdominal/pelvic CT showed multiple hypodense indeterminate lesions in the liver suspicious for metastatic disease and she was discharged on rivaroxaban. The patient has been followed at the cardiology clinic for 6 months and is doing well on anticoagulation.
This is an unusual description of an incidental discovery of right atrial thrombus in transit made at the time of planned TEE-cardioversion. Based on echocardiographic appearance, right atrial thrombus can be classified into three types: Type A thrombus is thin, highly mobile, and serpiginous, commonly originating from concomitant DVT; Type B thrombus is immobile and ovoid shaped, mostly associated with low flow states; and Type C thrombus has characteristics of both A and B (highly mobile but globular).1
Two main pathophysiological mechanisms of right atrial thrombus formation exist: (1) embolic due to propagation of a deep venous thrombus (DVT) or (2) in situ due to low blood flow such as atrial fibrillation or right-sided heart structural disease, or a hypercoagulable state that is inherited or acquired. Given the morphology of the thrombus in our patient, it is probably embolic in origin.
Multiple therapeutic options are available for patients with right atrial thrombus in transit including anticoagulation only, systemic thrombolysis, catheter-based thrombo-embolectomy, and surgical thrombo-embolectomy. There is a paucity of good randomized data in this field. However, in general, anticoagulation alone is not preferred as a therapeutic option as the mortality is higher with this approach.2,3 Surgical embolectomy is an established therapeutic option, but it was felt that the operative morbidity and mortality may be higher in our patient’s case, given her age and frailty. Systemic thrombolysis has been administered successfully for these patients, but again, the risk of bleeding was felt to be high due to her age.
Percutaneous catheter-based thrombo-embolectomy has been performed for right atrial thrombus. In prior years, basket-based systems have been employed for extraction.4,5 The operators have familiarity with two contemporary systems that have been commonly used for right atrial thrombus extraction: FlowTriever (Inari Medical) and AngioVac (AngioDynamics). Relevant features of both systems are shown in Table 1. The use of ICE guidance is very helpful to ensure catheter proximity to the free-floating thrombus at the start of the aspiration run to enhance procedural success and minimize blood loss.
We have described a case of percutaneous mechanical thrombo-embolectomy of free-floating right atrial thrombus using the Inari FlowTriever system. To the best of our knowledge, this is the second reported case of the usage of the Inari system for this indication and the first to be performed under ICE guidance.6
1Emory University School of Medicine, Department of Medicine, Division of Cardiology, Atlanta, Georgia; 2Morehouse College of Medicine, Division of Cardiology, Atlanta, Georgia; 3Grady Memorial Hospital, Atlanta, Georgia; 4Atlanta VA Medical Center, Division of Cardiology, Decatur, Georgia
Disclosures: The authors report no financial relationships or conflicts of interest regarding the content herein.
The authors can be contacted via Gautam Kumar, MD, at firstname.lastname@example.org.
- The European Cooperative Study on the clinical significance of right heart thrombi. European Working Group on Echocardiography. Eur Heart J. 1989 Dec; 10(12): 1046-1059. doi: 10.1093/oxfordjournals.eurheartj.a059427..
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- Burgos LM, Costabel JP, Galizia Brito V, Sigal A, Maymo D, Iribarren A, Trivi M. Floating right heart thrombi: A pooled analysis of cases reported over the past 10 years. Am J Emerg Med. 2018 Jun; 36(6): 911-915.
- Momose T, Morita T, Misawa T. Percutaneous treatment of a free-floating thrombus in the right atrium of a patient with pulmonary embolism and acute myocarditis. Cardiovasc Interv Ther. 2013; 28(2): 188-192.
- Mukharji J, Peterson JE. Percutaneous removal of a large mobile right atrial thrombus using a basket retrieval device. Catheter Cardiovasc Interv. 2000; 51(4): 479-482.
- Nezami N, Latich I, Murali N, et al. Right atrial and massive pulmonary artery mechanical thrombectomy under echocardiography guidance using the FlowTriever system. EJVES Short Rep. 2019 Nov 7; 45: 22-25.