Abstract
Background/Aim: Multiple aortic mural thrombi at the level of the ascending aorta represent a rare condition, only isolated cases have been reported so far. The aim of the current article was to report the case of a 61-year-old patient diagnosed with this pathology. Case Report: A 61-year-old patient with history of COVID infection six months previously was initially diagnosed with acute upper right limb ischemia and submitted to Fogarty desobstruction. Furthermore, the patient was diagnosed with a free-floating mass in the ascending aorta, for which he was submitted to aortotomy and floating thrombi, measuring 5.6×1.5 cm and 3×1.5 cm, were completely removed. The postoperative outcomes were favorable; at the three month follow up the patient proved to have a perfect circulated aortic lumen and supra-aortic vessels. Conclusion: immediate aortic desobstruction followed by reconstruction might be a lifesaving maneuver in ascending aortic thrombosis.
The presence of multiple aortic mural thrombi in the ascending aorta and aortic arch is a very rare condition, with an incidence rate of 0.45% (1), and it is incidentally identified by the manifestations of a systemic embolization or a computed tomography angiography (CTA). Aneurysmal disease, dissection or severe atherosclerosis of the aorta are conditions where an aortic mural thrombus can be found (2). In a normal non-aneurysmal, non-atherosclerotic ascending aorta (3), an aortic floating thrombus is very rare but can be suspected and should be carefully searched in patients with unexplained cerebral, visceral, or peripheral arterial embolism. When it is located in the aortic arch, there is an increased life-threatening risk of stroke (4).
Considering the position of the thrombus, the most common locations are the aortic isthmus, descending thoracic aorta, lower abdominal aorta, with the ascending aorta and aortic arch being the rarest (1). Depending on the implantation base, the aortic mural thrombi are sessile or pedunculated. The sessile thrombi are the most common, and the pedunculated ones, usually described as „floating thrombus”, are frequently associated with systemic embolism (3). There is no consensus in the literature regarding the etiopathogenesis of this pathology, nor the standard treatment protocol, with each case treated in a particular way.
Herein, we report the case of a 61-year-old male patient admitted to our institute with severe pain and paresthesia in the right forearm, pallor and absence of the radial pulse, suggestive for acute upper right limb ischemia with a 12-hour onset. Doppler ultrasound evaluation of the right arm identified the occlusion of the right radial artery, for which thromboembolectomy was performed. Further examinations performed to identify the source of the emboli, including transthoracic echocardiography (TTE) and computed tomography angiography (CTA), visualized a mobile echo-dense mass in the ascending aorta and aortic arch, which were successfully resected surgically. The histological examinations results showed that they were thrombi.
Case Report
A 61-year-old Caucasian male patient presented to our emergency institute with severe pain and paresthesia in the right forearm, pallor and absence of the radial pulse, suggestive for acute upper right limb ischemia, with a 12-hour onset. Six months prior to this admission, he was diagnosed with acute right inferior limb ischemia in a regional hospital, for which he received oral anticoagulation therapy. The symptoms were fully remitted, but no further investigations regarding the origin of the ischemia or the pathophysiology were made. The patient reported a medical history of systemic hypertension, dyslipidemia, former chronic smoker (stopped six months ago) and no history of atrial fibrillation. Also the patient had a previous history of COVID-19 infection seven months prior to this admission. On admission, the patient was hemodynamically stable, his blood pressure was 200/100 mmHg, heart rate 76 bpm, oxygen saturation level was 99% in atmospheric air, physical examination revealed the absence of the radial pulse, with pain, paresthesia, and pallor of the right forearm.
Laboratory tests demonstrated the presence of an elevated platelets number of 345,000/μl and C reactive protein high sensitivity of 11.03 mg/dl. The electrocardiogram (ECG) showed sinus rhythm with 82 bpm, with no ST-T modifications. Transthoracic echocardiography (TTE) visualized a mobile echo-dense mass in the aortic arch, with no signs of ascending aorta aneurysm (32 mm) or acute aortic dissection (Figure 1). No thrombus was identified in the left atrium or the left atrial appendage. Doppler ultrasound evaluation of the right arm identified the occlusion of the right radial artery.
Transthoracic echocardiography (TTE) visualized a mobile echo-dense mass in the aortic arch, with no signs of ascending aorta aneurysm (32 mm) or acute aortic dissection.
Computed tomography angiography (CTA) revealed a large, unregulated, oval-shaped, filling defect, suggestive for a thrombus, in the distal part of the ascending aorta, aortic arch and the proximal portion of the descending aorta, measuring 1.68×3.6×7.6 cm with some soft atheromatous plaques on the walls (Figure 2 and Figure 3).
Computed tomography angiography (CTA) revealing a large, unregulated, oval-shaped, filling defect, suggestive for a thrombus.
3D reconstruction revealing the presence of a large thrombus in the distal part of the ascending aorta, aortic arch, and the proximal portion of the descending aorta, measuring 1.68×3.6×7.6 cm.
The patient was transferred to the operating room for the surgical cure of the acute upper limb ischemia. Throboembolectomy of the radial and ulnar arteries was performed using a Fogarty catheter. The removed thrombotic material was sent to the anatomic pathology laboratory for evaluation. After the procedure, the right upper limb was completely functional, without pain, with normal color and with perceptible peripheral pulse.
Low molecular weight heparin was initiated. Further investigations regarding the etiology of the thrombus included screening for thrombophilia. We tested protein C (79%), protein S (59%), antithrombin III, and activated protein C Resistance-V, and the results demonstrated the presence of lower levels of Factor V. We excluded malignancy (no abnormalities in the complete blood count or tumor markers) and autoimmune disease, and also the blood cultures were negative.
Preoperative transesophageal echocardiography (EET) revealed a free-floating mass in the ascending aorta, mild mitral regurgitation, no sign of endocarditis, aortic valve insufficiency, or other pathological findings.
Considering the multiple ischemic events the patient already had, the location, dimensions and mobility of the thrombus, and the risk of forthcoming life-threatening embolization, the heart team explained and proposed the surgical procedure to the patient and he accepted. We started with the incision in the right subclavicular region, with identification and isolation of the right axillary artery, in order to establish the cardiopulmonary bypass (CPB) between the right axillary artery and the right atrium. After CBP was initiated, we started cooling the patient to 28°C aiming to obtain moderate hypothermic circulatory arrest to avoid cross-clamping the ascending aorta. We used retrograde cardioplegia for heart arrest. The cerebral perfusion was provided in a retrograde manner and the circulatory arrest was set. We used epiaortic ultrasound evaluation to determine the precise position of the thrombus/thrombi, if there is enough space for the aortic clamp and also, to determine the location of the aortotomy (Figure 4). This investigation confirmed the presence of 2 thrombi with different implantation bases. The origin of the first one was approximately 4 cm above the aortic annulus. The origin and the extension of the thrombi did not allow enough space to clamp the aorta in safe conditions.
Epiaortic ultrasound revealing the presence of 2 thrombi with different implantation bases.
A longitudinal aortotomy on the ascending aorta and first part of the aortic arch was performed, and the floating thrombi, measuring 5.6×0.5 cm and 3×1.5 cm, were completely excised, and the aorta was closed (Figure 5, Figure 6, Figure 7, and Figure 8). The patient was rewarmed and weaned from CPB.
Intraoperative aspect revealing the presence of large intraaortic thrombotic material.
Intraoperative aspect – retrieving the intra-aortic thrombus.
Intraoperative aspect – the final aspect after retrieving the thrombotic material and suturing the aortic breech.
Macroscopic aspect – the two retrieved thrombotic materials.
The postoperative evolution was uneventful, no recrudescence or concomitant visceral or peripheral embolism was observed, the postoperative transthoracic echocardiography showed normal heart morphology and function, and no sign of residual thrombus in ascending aorta or aortic arch.
The ICU stay was two days and the patient was discharged at home after eight days with anticoagulation therapy consisting of low molecular weight heparin therapy (LMWH) (enoxaparin, 8,000 units twice daily – Sanofi Aventis Romania, Bucharest, Romania).
The histological examination results showed that they were thrombi with exudative inflammatory cells, platelets, and no malignant cells (Figure 9).
Microscopic aspect – hematoxylin eosin staining (100× magnification) revealing exudative inflammatory cells, platelets, and no malignant cells.
At 3-months postoperatively, the patient was subjected to a control contrast-enhanced computed tomography angiography (CTA), which revealed no residual thrombus, with a perfectly circulated aortic lumen and supra-aortic vessels.
Discussion
The ascending aorta and the aortic arch are the rarest locations for an aortic mural thrombus. The presence of multiple floating thrombi with large dimensions in such a rare position without causing devastating complications has rarely been reported in the literature.
Given the paucity of the data in the pathophysiological mechanisms of the aortic mural thrombus, coagulopathy, autoimmune disorders, malignancies, atheromatous aorta, aortic wall structural abnormalities, trauma or substance abuse should be suspected and thoroughly searched in patients with cerebral, visceral, or peripheral embolism events (1). In our case, the only modified laboratory findings were a globally low level of V Factor. The CTA revealed the presence of some soft atheromatous plaques on the walls.
The least common thrombi are the pedunculated ones, known as ”floating thrombi”, but they are highly associated with embolic events with a risk of 73% (5). Combined with their presence in the aortic arch, the risk of a stroke is exponentially increased. The lower extremity arteries are the most common site for an embolus, which was the case of our patient. Six months prior to this admission, he was diagnosed with acute right inferior limb ischemia in a regional hospital. The oral anticoagulation therapy received at that time had successfully remitted the symptoms, but no further investigations regarding the origin of the ischemia or the pathophysiology were made. This led to a new embolic event, this time on his right upper limb. The next common embolic sites are the mesenteric and renal arteries, but this was not the case of our patient. Also, cerebral and coronary arteries embolism are very rare but life-threatening.
Another notable aspect from the patient medical history is that he had COVID-19 1-month prior to the first embolic event. The SARS-COV-2 virus primarily affects the lungs, but it can also cause cardiovascular complications. Several studies in the literature reported that COVID-19 may increase the risk of formation of blood clots by generating a higher inflammatory response in the body and by determining modifications in the histology of the blood vessels (6-8). SARS-COV-2 infection is known to induce a hypercoagulability state, either by an increase in prothrombotic factors, or endothelial damage followed by a massive release of cytokines and activation of complement pathways (7). This state increases the incidence of venous and arterial thromboembolic events, further increasing the mortality rate in frail patients (9). A recent study evaluated the incidence of thromboembolic events in admitted patients with COVID-19 and found that this category of patients are at high risk for developing thromboembolic events (10). More research is needed to determine the exact correlation and the mechanisms of formation of this cardiovascular complications.
Usually, aortic mural thrombi are associated with aneurysmal disease, dissection or severe atherosclerosis of the thoracic or abdominal aorta (11, 12). However, in our case, it was an ascending aorta without an associated aneurysm or dissection, representing a rare place and condition for thrombus formation. In a study of more than 10,000 autopsies, the authors reported a 0.45% incidence of thoracic aorta mural thrombus, with 17% of the cases presenting evidence of distal embolization (5).
Considering the rarity of the disease and also the absence of clinical manifestations before the embolic events, the diagnosis of floating aortic thrombi is mainly incidental and depends on imaging investigations. CTA together with TTE or TEE can very accurately evaluate the size, shape, location, implantation base and aortic wall characteristics. However, the limitations of the TTE and TEE are the distal part of ascending aorta and the proximal aortic arch due to the interference of the trachea. This is where the intraoperative epiaortic ultrasound evaluation has an important role. It can very precisely determine the position of the thrombus/thrombi, if there is enough space for the aortic clamp and also, it helps in choosing the location of the aortotomy. CTA is considered as a first-line examination (13). From our experience with this case, CTA combined with TTE, TEE, and epiaortic ultrasound assessment provides optimal visualization and accurate diagnosis and helps planning the surgical procedure.
There is no consensus in the literature regarding the standard treatment protocol, with each case treated in a particular way. The treatment strategies depend on the size, location, or the mobility of the thrombus as well as the history of embolic events, and include conservative approach with anticoagulants and endovascular or open surgical interventions (1). Since there are studies postulating that anticoagulation may lyse first the attachment site in thin pedunculated thrombi, increasing the risk of embolic events, the anticoagulant therapy, as the only treatment option, may be used in selected cases such as patients with no history of embolic events, small size thrombus with sessile implantation base or for cases where the surgical approach is contraindicated (4, 14).
The presence of symptoms or embolic events makes the surgical approach necessary. The surgical options in this case included excision of the thrombus and attachment site if needed, partial resection of the aortic wall or resection of the ascending aorta and aortic arch with graft interposition. In our case, after the excision of the thrombi, the aortic wall appeared macroscopically normal, with no atherosclerotic change or calcifications at the attachment place.
Conclusion
The presence of multiple floating aortic thrombi in non-atherosclerotic non-aneurysmal aorta are very rare and they carry a high risk of embolic events. In order to prevent catastrophic consequences, immediate treatment decision should be made consisting of early surgical removal with conservative anticoagulant treatment or endovascular intervention for specific cases. We consider that intraoperative epiaortic ultrasound evaluation is a valuable imagine tool that can precisely determine the location of the thrombi and help planning the surgical strategy.
Footnotes
Authors’ Contributions
RCG, RN, VAI, and OS designed the study; RPD and IM interacted with the patient; NB, IB, CD, and RCG collected data and drafted the manuscript; VC prepared the draft of the manuscript and performed literature review. All Authors read and approved the final manuscript.
Conflicts of Interest
The Authors have no conflicts of interest to declare in relation to this study.
- Received June 5, 2023.
- Revision received July 3, 2023.
- Accepted July 5, 2023.
- Copyright © 2023, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY-NC-ND) 4.0 international license (https://creativecommons.org/licenses/by-nc-nd/4.0).
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