Combining aortic arch dissection stent implantation and root surgery for aortic dissection type A

The reported study was performed in accordance with the principles of the Declaration of Helsinki.

All patients undergoing emergency surgery for AADA between 2010 and 2020 in our department (n = 370) were retrospectively reviewed in a single center non-randomized retrospective observational cohort study design. Patient with subacute or chronic aortic dissection were excluded from the database. Detailed inclusion and exclusion criteria applied for patient selection are listed in Table 1. As a standard procedure for surgical treatment of AADA patients, all patients underwent replacement of the ascending aorta with distal anastomosis performed in circulatory arrest allowing an endoluminal inspection of the aortic arch to exclude entry sites at this region. Further extension of surgery toward the aortic root or the aortic arch was performed wherever relevant valvular pathology or extensive dissection, or tear was present at the level of the aortic root, or when an intimal tear was observed at the level of the aortic arch, respectively. A total of n = 120 patients with combined aortic root surgery and replacement of the proximal aortic arch without further treatment of the arch beyond the innominate artery and the supra-aortic vessels were identified and included. Surgery of the aortic root was defined as valve-sparing aortic root repair by the David procedure or root replacement by the Bentall procedure. Isolated use of surgical glue to realign the layers of the aortic wall was not considered as root surgery and not included. AADA patients who received concomitant AMDS implantation (n = 9, operated between August 2019 and December 2020) were compared to the remaining AADA patients without AMDS implantation (Control, n = 111, operated between January 2010 and October 2020). The excluded patients (n = 250) underwent a variety of different types of aortic surgery, including patients with isolated hemi-arch replacement without concomitant root surgery as well as total arch replacement. In patients with an intimal tear in the aortic arch, frozen elephant trunk procedure with a hybrid prosthesis was regularly performed.

All patients underwent emergency on-pump surgery after confirmation of AADA by contrast-enhanced computed tomography covering at least the thoracic aorta. Surgery on the aortic root included valve repair by valve spearing root replacement according to David or valve replacement. A tube graft was used for proximal arch replacement. No further treatment of the arch and the supra-aortic vessels was performed in any of the included patients. All patients underwent circulatory arrest at body core temperature of 26–28 °C to inspect the aortic arch. Near-infrared intraoperative spectroscopy (NIRS) was used to monitor cerebral oxygenation, especially during CPB time and hypothermal circulatory arrest of the lower body. Unilateral antegrade cerebral perfusion was achieved by continuing perfusion of the right subclavian artery at 8–10 ml/min/kg body weight while clamping of the innominate artery. For bilateral antegrade perfusion, an endoluminal balloon-inflatable perfusion catheter was inserted into the left common carotid artery for pressure-controlled perfusion (target perfusion pressure 60 mmHg). Bilateral antegrade cerebral perfusion was initiated directly after the beginning of circulatory arrest and the release of the aortic cross-clamp as standard technique. Rarely was an additional endoluminal perfusion catheter inserted into the left subclavian artery to increase cerebral perfusion pressure through the left vertebral artery. In the control group, the dissected native ascending aorta was resected with resection line oftentimes extended into the minor curvature of the aortic arch, resulting in classic proximal arch technique. Adventitial felt stripe were used for re-enforcement of the anastomosis line. According to the intraoperative finding and surgeons’ preference also an additional endoluminal felt stripe was used in accordance with the sandwich technique. In AMDS group the ascending aorta was resected up to the intended anastomosis line in aortic arch zone 0. AMDS was implanted in line with the manufacturer’s instructions. Anastomosis between aortic arch with AMDS and the tube graft prosthesis of the ascending aorta was sutured with a modified cuffed anastomosis technique to prevent bleeding and potential future pseudoaneurysms [14, 15]. The size of AMDS was evaluated by measuring the diameter of the aortic vessel at the level between the innominate and the left common carotid artery, as well as at the level of the tracheal bifurcation in the preoperative computed tomography-angiography scan. The recommended size of the AMDS prosthesis (40 mm straight, 55 mm straight, 40/30 mm tapered, 55/40 mm tapered) was chosen according to the manufacturer's sizing sheet. Bilateral antegrade cerebral perfusion was continued during insertion of the AMDS delivery device and while sewing the proximal felt tube of AMDS to the native aorta. Shortly before finishing the suture line, cerebral perfusion was paused, the perfusion catheter removed to allow for completion of the suture line. Afterwards, the antegrade perfusion catheter were re-inserted through individual cells of the uncovered stent body and cerebral perfusion continued while anastomosing the ascending vascular tube graft to the already implanted AMDS. Following the manufacturer’s instructions for AMDS implantation, no specific anticoagulant or antiplatelet regime after stent implantation was initiated. Figure 1 shows the performed surgical procedures of both groups.

Incidence of major adverse cardiovascular and cerebrovascular events (MACCE) defined as postoperative stroke, in-hospital mortality and need for early re-intervention represent the combined primary endpoint of the study. ICU- and overall hospital stay, incidence of postoperative adverse events such as malperfusion, acute kidney injury or infective complications served as secondary endpoints.

Preoperative patient data including neurological status and hemodynamic is shown in Table 2. No significant differences were found between the two groups regarding demographic data as well as co-morbidities. None of the AMDS patients suffered from concomitant cardiopulmonary diseases such as coronary artery disease, diabetes or pulmonary diseases.

Table 3 displays detailed information about the operative procedures. There was a moderate trend towards increased EuroSCORE II in the control patients. All patients received replacement of the ascending aorta by a tube graft prosthesis. Aortic valve repair or replacement by implantation of a bioprosthesis was performed at similar rates in both groups, in about 50% of cases, respectively. While one third of the control patients received additional coronary artery bypass grafting (CABG), not a single coronary procedure was performed in the AMDS group (P = 0.06). Due to the more extensive surgery by additional AMDS implantation, duration of the CPB, aortic cross-clamping and circulatory arrest time of the lower body were prolonged in this group compared to the controls (P < 0.01). Nevertheless, there was no difference regarding intraoperative peak lactate values as well as required blood transfusions (P > 0.05).

Postoperative in-hospital outcome is shown in Table 4. We did not observe relevant differences in the evaluated postoperative parameters between AMDS and Control group. There was one patient of the AMDS group (EuroSCORE = 19.66%) with already preoperatively existing hemiparesis and transient loss of consciousness as well as intraoperative va-ECMO implantation who suffered from postoperative multiple organ dysfunction syndrome and consecutive in-hospital death (11.1%). This patient was also diagnosed with large cerebral infarction and represents one of the two patients with stroke in the AMDS group. In contrast, n = 24 (21.8%) of the control patient did not survive the hospital stay (P = 0.68). Incidence of stroke (AMDS = 22.2%, control: 17.0%, P = 0.65) as well as reoperations (AMDS = 33.3%, control: 25.9%, P = 0.70) as well as MACCE (AMDS = 44.4%, control: 38.7%, P = 0.74) did not differ either. The same effects were also observed for kidney injury, vascular interventions and infective complications. In addition, postoperative laboratory values and blood transfusions were comparable.