Aortic coarctation is one of the most dangerous diseases in cardiovascular surgery and is known for its high mortality rate, difficulty of treatment, many surgical complications, and poor treatment outcome. In particular, complex (type C) aortic coarctation has a wide range of lesions and often involves important large branch arteries, such as the unnamed artery, common carotid artery, and large visceral vessels, which can easily lead to poor perfusion of the patient’s nervous system and internal organs and even cause serious consequences such as stroke, paraplegia, ischemic necrosis of internal organs, ischemic necrosis of limbs, shock and death. Conservative medical treatment is not effective for patients with type C aortic coarctation, so the disease should be treated surgically as soon as it is diagnosed.
The main objectives of surgical treatment of type C aortic coarctation are to.
① Eliminate lethal risks, such as pericardial tamponade, aortic dissection, etc. ;
②Improve blood supply to vital organs;
③Treatment of proximal aortic lesions at the same time to eliminate the proximal rupture of the entrapment;
④Reduce the tension of the pseudocavity and promote the closure of the pseudocavity or the formation of thrombus in the pseudocavity;
⑤ Prepare the distal lesion for stage II surgery. For the surgical treatment of C-type aortic coarctation, especially Stanford AC) type aortic coarctation, if only ascending aortic replacement or partial arch replacement is performed, it is often impossible to completely remove the lesions in the aortic arch, and there is also a possibility that the postoperative head and arm vessels will be involved with the progression of the coarctation, resulting in impaired blood supply to the patient’s brain. Therefore, the best surgical procedure for type C aortic coarctation is total aortic arch replacement + elephant trunk surgery.
Traditional Elephant Trunk Surgery
Aortic arch surgery has always been one of the difficult aspects of aortic surgery, involving many important vessels, complicated operations, and high demands on anesthesia, management of extracorporeal circulation, and the surgeon.
The earliest aortic arch surgery was performed by DeBakey and Cooley in 1954 for distal aortic arch replacement, and in 1955, Cooley performed an attempt at aortic arch aneurysm removal and artificial vessel replacement without extracorporeal circulation, and in 1957, DeBakey performed a successful homograft replacement of the aortic arch under extracorporeal circulation. However, the incidence of neurological complications associated with aortic arch surgery was high.
In the early 1960s, Barnard, Schrire, and Borst advocated the use of deep hypothermic arrest circulation for cerebral protection in patients with aortic arch replacement, and then Griepp and others promoted the use of this technique, which significantly improved the efficacy of aortic arch replacement. 1983, due to the recognition that many complex types of In 1983, Borst et al. introduced the elephant trunk procedure, recognizing that many complex aortic coarctations required stage II descending aortic surgery.
The Elephant Trunk Procedure
To complete the elephant trunk procedure, the first step is to place an elephant trunk vessel, which is an artificial vessel folded and turned upward about 3 to 5 cm, with the short vessel facing outward. The turned bilayer vessel is inserted into the lumen of the descending aorta and the edges of the bilayer vessel are anastomosed to the descending aorta. After completing the anastomosis, the long part of the artificial vessel is pulled out of the vessel lumen, and the short outer layer is left in the descending aortic lumen. Finally, the aortic arch and the proximal aorta are operated on, and the aortic arch is generally insularly anastomosed (Figure 1).
The implementation of the elephant trunk procedure provides an opportunity for some patients who cannot undergo stage I total aortic replacement to undergo stage II surgery and reduces the difficulty of stage II aortic surgery and allows the proximal descending aorta, which has complex anatomy, to be avoided during surgery. However, in the course of performing total aortic arch replacement + elephant trunk surgery since 1997, the author has identified some inherent disadvantages of this procedure.
First, placement of the distal elephant trunk vessel is very difficult; type C aortic coarctation lesions tend to have insignificant distal aortic dilatation, the diameter of the false lumen is larger than that of the true lumen, and the tear in the intima of the aortic coarctation is often spiral, making it very difficult to place the soft elephant trunk vessel into the true lumen. Moreover, placement of the elephant trunk vessel prolongs the operative time and increases the complication rate of the patient.
Secondly, because the soft elephantine vessels are not tense and the true cavity of the lesion is narrow, the elephantine vessels are poorly dilated and easily kinked, and the blood flow is poor, which easily leads to poor perfusion of the spinal cord and visceral organs.
Third, the distal end of the soft elephantiasis vessels is not fixed and will oscillate with the blood flow in the aorta, which will easily lead to thrombus dislodgement and cause organ embolism.
Fourth, with traditional elephant trunk surgery, the rate of closure of the distal pseudolumen of the aortic coarctation is low, and patients have a high chance of reoperation.
Finally, hemostasis is difficult when reconstructing the cephalobrachial vessels using traditional island vascular piece anastomosis, and the preserved arch vascular piece has the potential for aneurysmal transformation.
Creation of the Sun’s procedure
In view of the inherent shortcomings of traditional elephant trunk surgery, Kato (Japan) and others attempted to perform elephant trunk surgery using a short stent technique at the distal end of the elephant trunk vessel, which served to fix the elephant trunk and avoid the artificial vessel from swinging in the aorta, but the clinical efficacy was poor and failed to be promoted. After exploration, the author developed a new fully stented polyester elephant trunk vessel (Figure 2) and created a new C-type aortic coarctation procedure, the Sun’s procedure (four-branch vessel total aortic arch replacement + stent elephant trunk procedure), based on this.
Fully stented polyester elephant nose vessels have the following advantages over soft elephant nose vessels.
(i) It has good self-expanding characteristics and can close the endothelial rupture of the aortic stenosis with good hemodynamics, and no kinking or poor dilatation will occur;
②The intraoperative placement is very easy, and anastomosis sites are left at both ends of the vessel to facilitate surgical operation; ③After release, it is more fixed and will not oscillate with blood flow to avoid thrombus formation.
Sun’s surgical method
The Sun’s procedure using a fully stented polyester elephant trunk vessel is suitable for most type C aortic coarctation lesions, including Stanford AC coarctation, Stanford BC coarctation, and Stanford B coarctation where interventional therapy has failed.
The Sun’s procedure offers many advantages.
①Simplify the procedure, shorten the operation time, and reduce complications due to extracorporeal circulation and deep hypothermic stop circulation;
(ii) Good stent-phantom vessel apposition, which allows reapposition of the separated aortic wall due to its self-expanding nature;
③Good hemodynamic effect, which effectively enlarges the true lumen and improves visceral blood supply;
④Reconstruction of the aortic arch with a four-branch artificial vessel can ensure cerebral blood supply, facilitate hemostasis, reduce bleeding complications, and avoid insular vascular sheet aneurysm transformation;
⑤ In terms of medium- and long-term regression, stenting the elephant trunk vessel can effectively promote the closure of the residual false lumen of the descending aorta and reduce stage II surgery.