Discussion
A mural thrombus of the thoracic aorta, that develops in the absence of pre-existing aortic disease, is a rare clinical finding with potentially devastating complications. Thrombus formation in the ascending aorta is an even more unusual event reported hardly before in patients with a non-aneurysmatic aorta12. The etiology of thrombus formation in a macroscopically normal aorta is not well understood. A correlation with underlying malignant disease, hypercoagulable disorders, endothelian disorders, steroid therapy, blunt trauma or even iatrogenic causes has been suggested345. In the presented case routine laboratory tests showed no abnormal findings and a coagulation disorder was excluded postoperative. Screening for cancer remains negative and the patient didn‘t had any B-symptoms. In the presented case, an endothelial lesion caused by a plaque rupture or the rupture of a vasa vasorum seems to be the most obvious origin of the thrombus formation.
As this remains a rare disease, there is no consensus on prognostic assessments or optimal treatment strategy. Therapeutic options include therapeutic anticoagulation, open surgical thrombectomy and endovascular treatment with stentgrafts. Medical treatment (anticoagulation, thrombolysis) may lead to complete dissolution of the thrombus in most of the cases. However, a careful patient selection is necessary and embolization remains the major concern with this approach6. Open surgery with segmental aortic resection provides optimal treatment in patients with local neoplasms or endothelial lesions of the thoracic aorta and eliminates the risk of embolic events. In the case of endothelial damage, the affected segment should be replaced, or if localized, like in our case, a patch repair should be used to cover the thrombogenic spot. Cardiovascular bypass should be established by cannulation of the subclavian or alternative femoral artery, in order to prevent cerebral thromboembolism. Preparation of the aorta before cross clamping is performed in no-touch technique. The endovascular approach is a much less invasive option than open surgery. However, the anatomical conditions must be suitable for stent release and there is an ongoing risk of distal embolism during intervention and wire manipulation.
Patient management includes a detailed patient history, clarification of coagulation disorders and tumor screening. A peripheral pulse status and possibly a Doppler sonography are part of the initial examination. Aortic CTA is recommended as first-choise examination because of availability and high sensitivity. For further evaluation of thrombus morphology, and to exclude intracardiac thrombi, a transthoracic or transesophageal echocardiography should be performed. A cranial CT is recommended in case of neurological symptoms. The therapy strategy is based on the thrombus morphology, location, patient age/ concomitant diseases and patient’s wishes. In case of a mobile, pedunculated mass with localization in the ascending aorta open surgical thrombectomy should be considered, due to high thromboembolic risk. The indication for surgery should be made particularly generous in young patients. In case of thrombus localization in the descending aorta endovascular stent graft exclusion seems to be an effective and safe option. It can be considered as well for failed medical and open surgical approach. Mural, broad based thrombi, behind the outlet of the left subclavian artery may be suitable for initial medical therapy, especially in high risk patients.