https://orcid.org/0000-0002-1714-0742
Abstract
A floating thrombus in the ascending aorta is rarely found in clinical practice and is an uncommon cause of peripheral arterial embolization. When there is minimal atherosclerosis or a normal aorta, the management of such a lesion is poorly defined. Currently, there is no clear consensus concerning optimal treatment. Herein, we report 2 cases of ascending aortic thrombus that are complicated by a peripheral embolic event. Due to the risk of recurrent systemic embolism, particularly with strokes, surgical thrombectomy with ascending aortic wall replacements was performed. We believe that floating ascending aorta thrombus represents a serious source of systemic embolism and stroke. Surgical removal is easy to perform with good clinical outcomes. Conservative treatments such as anticoagulation or thromboaspiration may be considered in high-risk or inoperable patients.
INTRODUCTION
A floating aortic thrombus is rare, especially in the absence of coexisting coagulation abnormalities or aortic wall lesions such as severe atherosclerosis and aneurysm. It is usually found during the diagnosis of an aetiological condition of systemic arterial embolism. The most common locations reported in clinical studies are the descending thoracic aorta and the aortic arch [1]. To date, there is no consensus on the management of this condition. Treatments may include anticoagulation, thrombolytics, aortic surgery and endovascular approach. In this paper, we report 2 cases of floating thrombus in the ascending aorta complicated by distal embolism that underwent successful surgical thrombectomy.
CLINICAL SUMMARY
Case report 1
A 43-year-old woman with a history of hypertension, diabetes mellitus and obesity was referred to our institution for management of left upper limb recurrent acute ischaemia. A computed tomography (CT) scan showed a mass attached to the distal part of the ascending aorta and floating in the aortic arch (Fig. 1A). Laboratory workup for autoimmune and coagulation disorders, such as anti-phospholipid syndrome and protein C, protein S and anti-thrombin III deficiency, was negative. The CT scan results showed that immediate surgical management was necessary to prevent recurrence of thromboembolic events. Under median sternotomy, cardiopulmonary bypass (CBP) was performed after innominate artery and right atrium cannulation. Hypothermic circulatory arrest with selective cerebral perfusion was undertaken. Aortotomy showed that a thrombus was attached to the ascending aorta with a mobile distal part floating in the aortic arch lumen (Fig. 1B). Detachment from the aortic wall was easy. Aortic wall examination did not reveal any macroscopic abnormalities except for small hyperplasic intima related to thrombus attachment to the aortic wall. We resected this segment of the aortic wall and reconstruction was performed using a Dacron patch. The postoperative course was successful, and the patient was discharged on day 5. Upon the initial follow-up, pathological and bacteriological examinations were negative. At the 24-month follow-up, there was no recurrent thrombus formation indicating a complete clinical recovery.
(A) Aortic computed tomography scan showing floating thrombus in the aortic arch. (B) Operative view: ascending aortic thrombus extended to the aortic arch lumen.
Case report 2
A 63-year-old-woman heavy smoker with a history of hypertension, diabetes mellitus and dyslipidaemia was admitted for left upper limb acute ischaemia. The CT scan showed a hypodense mass in the ascending aorta (Fig. 2A) with multiple splenic infarctions and embolism of the right renal artery.
(A) Enhanced computed tomography scan showing mass attached to the posterior wall of the ascending aorta. (B) Intraoperative image demonstrating ascending aorta thrombus.
After a multidisciplinary discussion, we decided to treat the intra-aortic thrombus before performing embolectomy of the left brachial artery. Via median sternotomy, normothermic CBP was initiated after the ascending aorta and right atrium cannulation. After transversal aortotomy, we found a mass attached to an atheromatous plaque of the posterior wall of the ascending aorta (Fig. 2B). An extraction of the mass, as well as an aortic graft interposition, was performed. Histological examination revealed a fibrin mass without tumour cells. Recovery was successful, and there was no recurrence of aortic thrombus at the 12-month follow-up.
DISCUSSION
Floating thrombus of the ascending aorta is rare and uncommonly described as the cause of peripheral arterial embolisms [2]. Intra-aortic thrombi formation is closely related to atherosclerotic lesions or hypercoagulable state due to genetic factors, other diseases or medical side effects [3]. This condition seems to be more frequent in women [4]. Diagnosis is usually made after recurrent embolic events. The management of the thrombus of the ascending aorta or the aortic arch is not well studied due to its low incidence and the lack of research. In a meta-analysis of 200 patients, thrombus location in the ascending aorta or arch, mild atherosclerosis of the aortic wall and stroke as presenting symptoms were identified as predictors of recurrent arterial embolization [1]. Nevertheless, we think that floating aortic arch thrombus should be distinguished as presenting a higher risk of cerebral embolization with significant clinical repercussion. This is why surgical removal should be considered in selected patients in whom aortic arch thrombectomy can be performed with a high degree of safety and efficiency. Although the absence of evident aetiology, primary thrombus of the aortic wall is constantly associated to intimal lesions or ruptures, which represent the ‘premium event’ inducing platelets aggregation and the formation of further thrombus. On the other hand, local recurrence of a thrombus at the same site of attachment has been described [5]. These arguments suggest that resection of the attachment site along the thrombus should be performed to prevent recurrences. Cannulation strategies are various and depend closely to the thrombus location to prevent its dislocation and complete removal. We recommend thrombus monitoring by transoesophageal echocardiography during opening and the preparation of CBP and cannulation. In the case of located thrombus at the distal part of the ascending aorta, cannulation of the right axillary artery may be a better solution. For a thrombus in the proximal part of the ascending aorta, arterial site cannulation can be done on the ascending aorta, the aortic arch or the brachiocephalic trunk. Anticoagulation treatment was related to high failure rates with the recurrence of embolic events requiring secondary aortic surgery. This finding can be explained by the fact that anticoagulation may trigger thrombus lysing at its attachment site before lysing the thrombus itself [6]. Less-aggressive approaches such as percutaneous thromboaspiration and endovascular repair were currently described as an alternative to the surgical approach [7, 8]. These innovative techniques are promising for high-risk or inoperable patients; however, their feasibility is limited to some experimented centres and has to be more widespread and reproducible.
CONCLUSION
Floating thrombus of the ascending aorta is a dangerous source of cerebral, visceral and peripheral embolism with potentially catastrophic repercussions. Thrombus location in the aortic arch should be considered a risk factor for recurrent embolism, and therefore, open thrombus removal with resection of the attachment site must be performed. Conservative treatment with anticoagulation may be considered in selected cases, such as high-risk and older patients with contraindications for surgery, as well as in asymptomatic patients.
ACKNOWLEDGEMENTS
The authors wish to thank the Mondor team of perfusionists for their collaboration.
Conflict of interest: none declared.
