In this paper, we described early and midterm results of TAP patients following TEVAR therapy. As a procedure with less invasiveness, short procedure duration and less bleeding, TEVAR is an ideal alternative of open surgery for aortic pathologies at distal aortic arch and descending aorta, especially for emergent situation with combined traumatic injury, severe infection and aortic rupture. TEVAR should be considered for TAP considering its emergency and complexity.
Atherosclerotic thoracic TAP accounts for the largest proportion (13, 35.1%) in our series. Actually, atherosclerotic aortic pseudoaneurysm generally originates from penetrating aortic ulcer (PAU) (2). We usually make the judgment based on patients’ advanced age, the gravity of aortic calcification by CTA and medical history of aortic ulcer or intramural haematoma by CTA results. A study showed that the survival of atherosclerotic TAP after TEVAR has a gradual yearly decreasing trend with 5-years survival lower than 40% due to extensive atherosclerosis of the aortic wall (17). The trend is unobvious in our results with 68-months survival as 67.7 ± 13.4%. In addition, one atherosclerotic TAP case in our series with extensive aortic calcification died of acute embolism of lower extremity. Therefore, like well-studied periprocedural stroke due to the displacement and embolization of aortic debris after TEVAR, perioperative embolism of lower extremity also deserves more investigation.
Blunt trauma is a mostly reported pathogenesis, and it has been a trend to use TEVAR to treat trauma related aortic pathologies. 7 (18.9%) trauma TAP cases in our series all received TEVAR therapy, and no complication and death was observed during the follow up (Fig. 2C). The result is understandable due to healthier and younger vessel nature based on trauma patients’ relative younger ages (52.9 ± 9.6 years, 44 to 68) than atherosclerotic patients (66.9 ± 8.1 years, 56 to 82). According to the literatures, the line between nonoperative management (NOM) and operative treatment for grade III (pseudoaneurysm) blunt traumatic aortic injury (BTAI) remains blurred. Some studies suggested that BTAI with pseudoaneurysm could be managed by NOM instead of instant operative treatment (9, 18). However, there was 10% risk of TAP requiring surgical therapy after NOM (18), and postdischarge follow-up was restricted to < 1 year in most studies (19). Based on our series, we suggest that instant TEVAR for traumatic TAP is reasonable.
Infected TAP is a tough condition with high mortality (20–23). This microorganisms reach the vessel wall through various ways including direct invasion and spread, feeding vessels, lymphatic vessels and iatrogenic factors. Despite the controversy of treatment with artificial graft exposed to infected tissue, many studies have shown that endovascular repair is a palliative treatment in acute phase, a temporary bridge to secondary open surgery (20, 24–26). For patients only undergoing endovascular treatment, life-long appropriate antibiotic therapy, or regular and full-course anti-tuberculous chemotherapy is recommended (27). 4 (10.8%) infectious cases originated from AEF, which was caused by esophageal foreign bodies in 2 and previous stent grafting in 2. Blood culture was positive for staphylococcus aureus in one case. Moreover, there were 7 (18.9%) tuberculosis TAP patients having received TEVAR in our series, and satisfactory early and midterm outcome had been obtained: patients gained weight during follow up, with 1 month and 51 months survival as 85.7 ± 13.2% and 71.4 ± 17.1%.
For patients with infected TAP, innovative adjunctive procedure in addition to TEVAR was adopted in our center, which might contribute to the satisfactory outcome and has been published recently for the first time (16). After the deployment of aortic stent sealing the aneurysm sac, directly delivering the antibiotic agent to the aneurysmal sac via pre-placed catheter would ensure that the drugs would permeate into nearby tissues continued and slowly instead of being swept away by blood stream. Moreover, in situ administration might improve drug bioavailability compared to oral or intravenous administration.
Systemic vasculitis is another intractable pathogenesis of TAP, and the outcome of them was unsatisfactory albeit following immunotherapy (Fig. 2C). Some experience on TEVAR for systemic vasculitis has been reported, which is superior to open surgery on preventing immediate complications and aortic anatomical pseudoaneurysm. However, recurrent TAP remains to be a continuing problem because of aortic wall injury or mechanical force at the edge of the stent triggering vascular inflammation (28). It is suggested that adjunctive perioperative and postoperative immunosuppressive treatment is essential (29, 30).
Two cases having received TEVAR due to previous aortic dissection developed distal TAP with secondary AEF, and the time to the development of AEF after TEVAR respectively was 39 months and 8 years. A multicenter study showed that the occurrence of AEF after TEVAR was 1.5% and the median time was three months (31). The incidence of distal TAP is a joint result of the unsolved underlying aortic inflammation at the time of TEVAR or mismatched oversize proportion of the stent, plus the mechanical force at the edge of the stent. The mechanical compression and secondary invasion from TAP might be the cause of AEF considering 2-years dysphagia history of our patient.
Symptomatic cases accounts for 83.8% (31/37) percent of overall TAP patients. The most common symptom was chest/back pain or tightness (56.8%, 21/37). It was back pain and distress in another study (17). Actually, hemoptysis, hematemesis, hematochezia and melena are strikingly noticeable as quite common symptoms of respiratory and digestive diseases. They occurred due to aortopulmonary fistula (APF) or AEF even with a visible intrabronchial or intraesophageal mass (24, 32–37). In such situations, endoscopic clamping biopsy poses a risk of massive bleeding. There was no detectable APF in our patients manifested as hemoptysis, albeit in one patient who complained of persistent hemoptysis for even seven years after TEVAR. Under this circumstances, respiratory disorder is more likely to be considered.
Our results suggest that patients with zone 4 TAP have a significantly more favorable midterm outcome than zone 3 TAP. A similar study also indicated the existence of better death/survival ratio among patients with middle thoracic aneurysms than among patients with aneurysms situated at proximal aorta (38). On one hand, when the orifice of LSA that was only partially covered by the stent, local fluid dynamics showed remarkable disturbance (39). On the other hand, zone 4 aneurysms, with sufficient proximal landing zone, could receive a straightforward endovascular surgery without secondary endovascular intervention and thus avoid relevant complications, having greater chance of satisfactory survival (38). However, a single-center research on TEVAR for thoracic TAP, with 24.0 ± 18.5months (range, 1.5 to 67.3) follow-up, showed no evidence about this (17). It might because that they only focused on univariate effect and ignored the interaction between covariates. In univariate analysis, they found that surgery opportunity, emergent or elective, had significantly distinctive effect on the survival, which is consistent with our finding.
Clinical indications for emergent/urgent TEVAR includes ruptured descending thoracic aortic aneurysms, acute BTAI and complicated acute type B aortic dissections (40). In our series, TAP patient with AEF manifested as massive haematemesis or hematochezia was also indications. Although TEVAR therapy could prevent death by exsanguination, the survival outcome is not desirable due to high risk of infectious complications and failure to solve fundamental cause. AEF patients following open management also had poor outcome including implantation of vascular prosthesis and patch repair (41). The latest research indicated that in situ aortic replacement by cryopreserved aortic homograft and concomitant primary closure of the esophagus is a feasible and promising therapy for primary and secondary AEF (42).
TAP patients with cardiac disease (16.2% of the series) as an independent risk factor were proved to pose a 4.9-fold increased risk to worse late survival outcome. Patients with coronary disease also developed aortic calcification, particularly the occurrence of atherosclerotic aortic aneurysm reached 46.3%. A research suggested that cardiac catheterization before TEVAR is necessary for evaluating coronary arteries’ condition and predicting the degree of aortic calcificion (43).
In this series of TAP, the mortality at 1 and 5 years was 75.9 ± 7.5 and 68.3 ± 9.9, which was a satisfactory result comparing to open surgery(44). The mortality of over 10% at 3 months might links to patients’ complex condition or early complication of TEVAR. As a research showed that once emergent cases survived TEVAR procedure, the survival of them become stable after 6 months(17).
Although there are several results in this report, there are also limitations. Actually, the effectiveness of endovascular therapy is underestimated because we only calculated all-cause mortality and concomitant cardiac disease was proved significantly associated with TAP patients’ survival. It is a retrospective observational study based on single center experience with a long time span and limited cases. Cohort study and randomized controlled trial are needed to further demonstrate our results.