Aortic coarctation is a serious class of life-threatening diseases. The application of thoracic endovascular aortic repair (TEVAR) for aortic coarctation has created a milestone in the treatment of Stanford type B aortic coarctation. TEVAR has the advantages of high success rate, low trauma, and low mortality, but it has some complications, among which type I endoleaks may lead to retrograde type A aortic coarctation or coarctation rupture, which may threaten patients’ lives. Meanwhile, with the widespread use of TEVAR surgery, the treatment strategy of type I endoleaks has become the focus of attention. Therefore, this paper focuses on the treatment of type I endoleaks after TEVAR surgery, which has important clinical significance for reducing the mortality of such complications.
1. Data and methods
1.1 Study subjects
The clinical data of patients with type I endoleaks after TEVAR for Stanford B type aortic coarctation admitted to Beijing Anzhen Hospital of Capital Medical University from March 2009 to January 2013 were reviewed. A total of 20 patients in this group were enrolled in the study. Patients underwent thoracic macrovascular CTA, echocardiography, and chest radiography upon admission to clarify the location of type I endoleaks after TEVAR and the extent of entrapment involvement. Patients who were to undergo stenting elephant trunk were required to undergo coronary imaging to exclude coronary artery disease if they were R50 years old.
The surgical approach was decided according to the patient’s age, general condition, the location of type I endoleaks, and the location of the proximal end of the overlapping stent for the first TEVAR procedure. The 2 groups were divided into the stent elephant trunk group (12 patients) and the re-TEVAR group (8 patients) according to the surgical approach. The postoperative follow-up was 6-48 months with a mean of 6.53±7.60 months.
1.2 Surgical methods
All stent elephant truncal procedures were performed under general anesthesia with extracorporeal circulation. The ascending aorta, aortic arch and cephalic trunk vessels were freed. Depending on the condition, the right axillary artery, ascending aorta or femoral artery was selected for cannulation, and the right atrial cannula diode was inserted to establish extracorporeal circulation. When the nasal temperature dropped to 22-25℃, the cephalic trunk vessels were blocked, and the circulation was stopped by cannulation through the right axillary artery or the nameless artery (patients with femoral artery cannulation need to place a separate 14F arterial cannula in the nameless artery; patients with ascending aortic cannula can insert the ascending aortic cannula directly into the nameless artery) for selective cerebral perfusion. The aortic arch is transected between the left common carotid artery and the left subclavian artery to explore the anterior wall of the aortic arch for endoleaks and stent location.
If the leak is clearly exposed, the leak can be sutured closed; if the bare area of the interventional stent obstructs the suture of the elephant trunk stent, part of the bare metal stent can be cut out or the interventional stent can be removed; if the leak involves the opening of the left subclavian artery, the proximal end of the left subclavian artery can be sutured closed, the left subclavian artery can be truncated, and its distal end can be anastomosed with the left common carotid artery to establish a left common carotid artery to left subclavian artery diversion or an 8 mm artificial vessel can be used to ascend the aorta to the left axillary artery or the left subclavian artery. Aortic to left axillary artery or left subclavian artery.
A 26-30 mm Microport intraoperative stent vessel was placed in the interventional stent to cover the endoleaks, and the aortic arch incision was closed with continuous sutures of 4-0 prolene suture fixed around the entire circumference of the aortic arch wall. Reheat, ventilate, open the head and arm stem blocking clamp and femoral artery blocking clamp (can be withdrawn at the same time as the nameless artery cannula), and restore normal flow extracorporeal circulation. Open the aortic block clamp when rewarming to about 28℃ to complete cardiac resuscitation. After rewarming is completed and the circulation is stable, stop the extracorporeal circulation. Remove all intubation tubes. Heparin is neutralized with ichthyosperm, hemostasis is achieved, the chest is closed, and the procedure is completed.
The aortogram was performed under local anesthesia with a catheter placed in the free femoral artery to clarify the location of the leak, and the overlapping stent was selected based on the diameter of the proximal artery and the diameter of the original overlapping stent (usually the diameter of the overlapping stent was larger than the diameter of the original overlapping stent for reoperation). anchoring zone, the left subclavian artery was closed.
In two cases, the proximal anchorage zone was insufficient to cover the location of the internal leak, and Hybrid surgery was performed because the patient could not tolerate open thoracic surgery. A Gore-tex 8 mm branch vessel was first applied to divert the right axillary artery-left axillary artery and the left common carotid artery, and then the overlapping stent was placed through the femoral artery with its proximal end positioned distal to the opening of the innominate artery, followed by embolization of the left subclavian artery opening with a vascular plug placed through the left axillary artery.
1.3 Statistical methods
The measurement data were expressed as mean ± standard deviation (±s), and the count data were expressed as percentages (%). t-test of two independent samples was used for comparison between 2 groups for measurement data, and x2 test was performed for count data. Statistical analysis was performed with spss13.0, and p<0.05
2, Results
There were no statistical differences between the 2 groups in terms of age, height, weight, family history, history of hypertension and interval from the first TEVAR procedure. There were more men in the stent elephants than in the TEVAR group (p=0.049). 12 cases of stent elephants were elective procedures, of which 4 cases had the metal stent in the bare area of the interventional stent clipped; 1 case had the interventional stent removed; 3 cases had the proximal stent vessel anastomosed distal to the left subclavian artery and 8 cases were anastomosed between the left common carotid artery and the left subclavian artery; 4 cases had the left common carotid artery to left subclavian artery Among the 8 patients who underwent TEVAR again, 2 patients underwent Hybrid (right axillary artery-left axillary artery and left carotid artery). Among the eight patients who underwent re-TEVAR, two underwent Hybrid (right axillary artery-left axillary artery and left common carotid artery diversion + left subclavian artery embolization + TEVAR) and the rest underwent simple re-TEVAR.
There were no significant differences between the 2 groups in terms of length of stay, location of the leak, complications, and follow-up mortality. In the perioperative complications, there were two cases in the stent elephant trunk group, including one case of sternal doffing, which was cured by re-stenting; one case of preoperative renal insufficiency and postoperative acute renal failure, which recovered after dialysis treatment. In one case, the patient had severe postoperative chest pain, and CTA showed severe proximal endoleakage of the stent and severe compression of the true cavity, and “elephant trunk surgery” was performed under deep hypothermic selective cerebral perfusion in an emergency. In one case, the left thoracic hemothorax occurred after emergency surgery with aortic coarctation, and the left thoracic clot was removed by opening the chest, and the left subclavian artery was closed during TEVAR again.
In terms of operative time, the stenting elephant trunk group was significantly longer than the re-TEVAR group (P=0.007), but in terms of endoleak elimination rate in both groups, 50% of patients in the re-TEVAR group still had endoleaks (P=0.014). During postoperative follow-up, one case of stent infection, hemoptysis, and death occurred 7 months after surgery in the elephant trunk stenting group, whereas there was no death in the re-TEVAR procedure group (P=1.000).
3, Discussion
Endoleak after TEVAR is one of the major complications affecting the outcome of Stanford B aortic coarctation, which is usually divided into type IV, of which type I endoleak refers to the proximal endoleak of the overlapping stent, the occurrence of which is usually considered to be due to four reasons: first, insufficient distance between the proximal anchorage area of the aorta, second, inaccurate positioning or displacement of the overlapping stent, third, poor adhesion of the overlapping stent to the aortic wall due to compression of the true lumen into the angle, and fourth, poor adhesion of the left subclavian stent to the aortic wall. The fourth is the regurgitation of the left subclavian artery. Because the high velocity and high pressure blood flow directly rushes into the gap around the graft, it has less chance of self-closing. Moreover, with the partial thrombosis of the false lumen after endoluminal repair, this type of endoleak may evolve into a blind pocket that only enters and does not enter, which may cause the pressure of the false lumen to rise rapidly and even lead to aneurysm rupture.
If an endoleak is found during TEVAR, it should be treated aggressively. Usually, regardless of whether the entrapment tear produces a new rupture, an upward expansion of the original rupture, or a gap between the graft and the wall, it can be treated by reinserting one or even more grafts proximally until the imaging shows that the endoleak is eliminated. Since the sensitivity of aortic CTA scan for endoleaks is 92% and the specificity is 90%, it is considered the preferred method to detect endoleaks, so patients should routinely receive follow-up aortic CTA examinations after TEVAR. If it is clear that an endoleak remains, further management is required.
The stenting elephant trunk procedure has been adopted by several vascular centers with good results after it was applied by Kato et al. in 1996 for the treatment of thoracic aortic coarctation in the arch. In 2003, Sun Lizhong et al. further improved the stenting elephant trunk material and successfully developed the CronusTM intraoperative stenting vessel. This international first artificial vascular material and its applied surgical technique have been popularized in China and abroad, and good results have been achieved in the treatment of aortic arch lesions. type I endoleaks after TEVAR, the leaks are mostly located in or adjacent to the aortic arch, and the treatment method needs to ensure the effective sealing of the leaks on the one hand and the protection of the head and arm vessels on the other hand, so the accurate positioning characteristics of the graft are highly required.
Summarizing the previous clinical experience of applying domestic intraoperative stent vessels, we adopted stent elephant trunk surgery for this group of patients because of its characteristics of accurate positioning, artificial vessel suturability and exact repair of the breach (leak), which meet the treatment needs of type I endoleaks. The results showed that this group of cases achieved a good result of 100% closure of the leak.
The reasons for this are: the surgical operation under direct vision can clearly explore the location of the leak, and if necessary, the leak can be closed by direct suturing; the intraoperative stent is placed with accurate positioning to ensure that the proximal end of the artificial vessel is positioned in the normal arterial wall; the stent is fixed in the aortic wall by full suturing, and the stent displacement and thrombus dislodgement of the breach can be closed exactly to cause limb embolism; it has the self-expanding characteristic, which can make the fit between the overlapping stent and the true and false lumen of the aortic stent more The self-expanding property of the stent can make the cladding stent and the true and false lumen of the aorta fit more tightly; cutting the wire in the proximal bare area of the cladding stent can avoid excessive tension on the arterial wall.
By simultaneously performing left common carotid to left subclavian artery diversion, the stent vessel is released between the left common carotid artery and the left subclavian artery to close the opening of the left subclavian artery, which can further guarantee the sealing of the leak and make the operating distance between the anastomosed artificial vessel and the aortic wall significantly shorter, reducing the difficulty of surgical operation, making the anastomosis more accurate, shortening the time of low-flow selective cerebral perfusion, and improving the cerebral protection effect.
The disadvantages of this type of surgery are the greater trauma, extracorporeal circulation and complications associated with blood loss, the relative difficulty of surgical operation, and the high level of requirements for the medical work teams of anesthesia, extracorporeal circulation, and monitoring rooms, which limit its widespread use. In this group of patients, there was one long-term follow-up death, whose postoperative follow-up CTA showed perigraft infection, which may be related to bacterial colonization during surgery. Therefore, reducing the surgical trauma, simplifying the surgical operation method and shortening the operation time will be the future improvement direction of this type of surgery.
The advantage of TEVAR surgery is that the surgical trauma is small, the surgical operation and perioperative treatment are relatively simple, the operation time is short, and there is basically no risk of blood loss; at the same time, as a minimally invasive surgical method, the psychological impact on patients is small, and the perioperative quality of life is improved.
The disadvantage is that the accuracy of positioning is limited by the operator’s experience, instrumentation and clear judgment of two-dimensional images, and again TEVAR is constrained by the distance of the proximal anchorage area, which requires extremely high accuracy of overlapping stent positioning for endoleak closure, increasing the difficulty of the operation; at the same time, due to the placement of a larger diameter overlapping stent, the pressure on the arterial wall further increases, which in turn damages the endothelium of the artery and may lead to the occurrence of a new leak; in addition In addition, displacement of the overlapping stent, poor adhesion of the re-intervention stent to the original stent, and regurgitation of the left subclavian artery may lead to poor closure of the leak.