Behcet's disease (BD) is a rare, chronic, autoimmune, multisystem disorder that can cause inflammation of blood vessels anywhere in the body. BD could affect various types of vessels and cause variable kinds of pathologies. As arterial complications, the development of true or false aneurysms in great vessels accounts for 1–7% of BD patients [6]. The common sites of aneurysm related to BD have been reported as abdominal aortic aneurysm, pulmonary aneurysm (Fig. 6), carotid artery aneurysm, and lower extremity aneurysm. However, aortic pseudoaneurysm is the most disaster in BD, and aortic aneurysm rupture has become the principal cause of death in BD with vascular complications.
Aneurysm formation of the thoracic aorta is a rare but serious manifestation of BD. If thoracic aortic aneurysms (TAA) ruptures into the lung parenchyma or tracheobronchial tree, patients would suffer massive life-threatening hemoptysis, different from those common causes such as bronchiectasis, tuberculosis, fungal infections, and cancer. There was not any other evidence except for a definite history of BD in our patient when TAA was first identified to be responsible for initial hemoptysis, which suggested that the vascular lesion was not an isolated event but was associated with BD. Practically, detailed medical history and careful physical examination are of great value in occult onset patients. More interestingly, recurrent hemoptysis occurred 4 years later due to aortic-arch pseudoaneurysm invading into the left main bronchus based on CT evaluation. According to our speculation, the fistula developed between the aorta and the tracheobronchial tree possibly because erosion from the continuous pulsatile pressure from arterial blood flow and gradual enlargement of the pseudoaneurysm resulted in compression necrosis of the main bronchus. Radiographic screen like CTA provides direct evidence for the two episodes of hemoptysis in this patient.
The major problem of open surgical treatment for BD-associated aortic pseudoaneurysm is its tendency to develop recurrent false aneurysm at the anastomosis site, which occurs in 30–50% of patients [3]. TEVAR, introduced in the mid-1990s, provides a less invasive approach to treating acute and chronic thoracic aortic pathology with reduced surgery time and a more rapid recovery. Additionally, this therapy also causes less blood loss and has lower mortality rates. Considering these advantages, recent studies support endovascular repair and believe that it challenges conventional open surgical repair for the management of TAA, with systemic immunosuppressive and anti-inflammatory treatment before and after surgery in active BD [7,8,9,10,11]. Even so, recurrent pseudoaneurysm is still a serious problem in BD patients [12]. In our patient, thoracic descending pseudoaneurysm was candidate for endovascular repair based on the adequate anchor zone at his initial consultation. His recurrent aortic-arch pseudoaneurysm was highly suspected to be associated with poor attachment of the proximal stent based on the imaging appearances of a 1-year follow-up CTA. Meanwhile, vessel wall injuries or mechanical stress at the edge of the stent graft may trigger tissue inflammation together with arterial pulsation. Recurrent pseudoaneurysm at the margin of the stent graft requires timely intervention with additional stent graft.
With the continuous improvements in stent grafts and technical experiences, indications of TEVAR for aortic pathology are constantly enlarged. For those vascular lesions involving the aortic arch, important arterial branches, and a short anchor zone, the use of a common configuration of stent graft often leads to various types of severe complications. Parallel to the main aortic stent graft, the chimney technique uses a covered or bare stent to maintain blood flow to the vital organs, which could be indication to treat lesions with inadequate anchor zones. In our patient, the chimney stent was implanted into the left common carotid artery, while the left subclavian artery was sacrificed. A reversal of the left vertebral flow to the left subclavian artery was observed by the postoperative carotid Doppler, indicating the occlusion of its proximal end and the establish of collateral circulation. TEVAR combination with the chimney stent is a valid solution to the critical location of an aortic aneurysm in an emergency setting. A study combining TEVAR with the chimney technique revealed that the chimney-graft technique for aortic-arch pathologies is technically applicable in both elective and emergency situations, and is associated with satisfactory perioperative outcomes with a success rate of 90.2% [13]. Our successful management demonstrates that this approach may be an attractive therapeutic alternative to treat aortic-arch pseudoaneurysm for those high-risk surgical candidates. Meanwhile, the placement of the endovascular stent should be such that the proximal end does not lie in the convex of the proximal thoracic descending aorta, and it should be either positioned more proximally into the arch or distally into the straight portion of the thoracic aorta, as the lesson learned from our patient. The precise evaluation for therapeutic effect is easily obtained by CTA [14], similar to our screen.
In conclusion, TAA related to BD is rarely encountered, which is one of the rarest causes of life-threatening hemoptysis. TEVAR can be used as an effective and problem-solving treatment approach for TAA eroding into the lung, even recurrent pseudoaneurysm after initial TEVAR in BD patient. TEVAR combined with the chimney technique widens the indication for aortic pathology. Among the imaging methods assessing the technical success, outcome, and complications, CTA offers a fast, accessible, and sensitive imaging modality.
