Preliminary experience of endovascular treatment of acute mesenteric occlusion in stable patients with acute type A aortic dissection

Introduction

Stanford type A aortic dissection is a life-threatening emergency that frequently necessitates urgent surgical intervention (1). However, the aortic dissection, with heterogeneous extent and duration, leads to compromised organ perfusion in approximately 25% of patients. The natural progression of Stanford type A aortic dissection is associated with a high mortality rate, reaching approximately 30% within the first 24 hours of onset and escalating to 93% within one month (2). The leading causes of fatality are organ malperfusion syndrome, cardiac complications, and aortic rupture. Patients presenting with Stanford type A aortic dissection complicated by acute occlusion of the superior mesenteric artery (SMA), in particular, exhibit an exceedingly high mortality rate, ranging from 41% to 100% (3), even if emergency surgery for ascending aorta repair is performed. The main contributors to this elevated mortality are intestinal necrosis syndrome and acidosis. Real-world studies have shown dismal results and high mortality rates using emergency central open repair (4-9), consequently, appropriate management of acute SMA occlusion arising from acute Stanford type A aortic dissection is crucial.

SMA occlusion due to Stanford type A aortic dissection can be divided into three types according to the anatomic structure: the dynamic, static and mixed types. Dynamic obstruction is due to insufficient blood flow through the true lumen, and the pressure difference between the false lumen and the true lumen causes the false lumen to prolapse into the ostium of the SMA, causing obstruction. Static obstruction is caused by either an intimal flap obstructing the ostium of the artery or a false lumen protruding into the branch vessel with thrombosis, resulting in SMA occlusion (10,11). Dynamic obstruction is more often the cause of malperfusion syndrome than static obstruction and is responsible for approximately 80% of cases. Immediate central aortic repair for dynamic obstruction can restore the true lumen blood flow. When the pressure in the true lumen exceeds that in the false lumen, the ostium of the SMA would reopen. However, if the SMA occlusion type is static, SMA stent implantation may be needed (12) with mesenteric malperfusion not being resolved by open surgical repair. As detailed here, over 12 years, in conjunction with cardiac surgery, we used interventional therapy as the first intervention to successfully manage 11 consecutive patients presenting with acute static or mixed SMA occlusion resulting from acute Stanford type A aortic dissection. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-881/rc).

Methods

Clinical data

This study comprised 11 consecutive patients diagnosed with acute true lumen occlusion of the SMA induced by acute Stanford type A aortic dissection with hemodynamic instability, as confirmed by computed tomography angiography (CTA) of the thoracoabdominal aorta at an external hospital. These patients were referred to the first affiliated hospital of Guangzhou medical university and treated between March 2010 and November 2022. This study was approved by the Ethics Committee of The First Affiliated Hospital of Guangzhou Medical University [No. GDREC2018215H(R3)]. All the participants signed a written informed consent form. This study was conducted in accordance with the Helsinki Declaration (as revised in 2013). Based on the classification criteria outlined in the pertinent guidelines, SMA involvement was categorized as static or mixed type (13).

Abdominal aortography and mesenteric artery intervention therapy

Figure 1 illustrates the procedural sequence. At admission, all patients exhibited abdominal distension and pain. All were expeditiously escorted to the interventional suite via the prioritized green channel of the chest pain center. After standard sterilization and draping procedures, the left or right femoral artery was punctured under local anesthesia using 2% lidocaine. A 7/8F femoral artery sheath was inserted, followed by administration of 1,000 U of heparin. Thereafter, a combination of catheters and guidewires was utilized to discern the true and false lumens of the abdominal aorta segment. Abdominal aorta angiography then was conducted with a 5F PIG catheter, and the SMA visualized. Next, a 7/8F JR4.0 guiding catheter was exchanged and precisely positioned at the SMA ostium. Coronary guidewires, including sion/sion blue/Runthough, were subsequently employed to locate the true lumen of the SMA. When locating the latter proved challenging, a coronary thrombus aspiration catheter was utilized as a dual-lumen catheter to aid in the procedure. The parallel wire technique was employed, and gentle aspiration chamber angiography was conducted with the thrombus aspiration catheter. After the guidewire successfully reached the vessel’s distal end with clarification of the distal true lumen and extent of dissection involvement, an extra 3,000 U of heparin was administered. Thereafter, peripheral self-expanding bare metal stents or carotid artery stents were systematically deployed, commencing from the normal segment distal to the dissection and progressing towards the ostium of the SMA. When the dissection affected the more distal portion of the SMA with a reduced vessel diameter, coronary stents were prioritized for placement. Peripheral self-expanding bare metal stents or carotid artery stents were subsequently linked in sequence until they reached the ostium of the SMA. Proximal stents typically extended into the abdominal aorta by approximately 5 mm. Following stent deployment, superselective angiography of the SMA was conducted to evaluate the effectiveness of the interventional treatment. After satisfactory visualization of the SMA, the patient was promptly transferred to the operating room, and cardiac surgeons performed procedures, including ascending aorta replacement and/or aortic valve replacement.

Figure 1 The static type and mixed type of SMA occlusion caused by type A aortic dissection and presentation of one representative case interventional treatment and follow-up results. (A) Aortic CTA shows type A aortic dissection, SMA occlusion (static type) (indicated by the arrow). (B) Aortic CTA shows type A aortic dissection, SMA occlusion (static + dynamic type) (indicated by the arrow). (C) Selective angiography of SMA confirming occlusion (indicated by the arrows). (D) Place the coronary thrombus aspiration catheter in the distal lumen of the superior mesenteric artery and perform angiography to clarify the morphology of the distal vessel (indicated by the arrow). (E) The coronary thrombus aspiration is gradually withdrawn from the distal of the superior mesenteric artery, and angiography is performed to identify the affected area of the dissection (indicated by the arrows). (F) After placing stents from the distal segment to the ostial of SMA, angiography showed that the SMA is unobstructed (indicated by the arrows). (G) One month later, aortic CTA showed that the stent of the superior mesenteric artery is unobstructed (indicated by the arrow). (H) Six months later, aortic CTA showed that the stent of the superior mesenteric artery is unobstructed (indicated by the arrow). (I) Twenty months later, aortic CTA showed that the stent of the superior mesenteric artery is unobstructed (indicated by the arrow). SMA, superior mesenteric artery; CTA, computed tomography angiography.

Postoperative treatment and follow-up

Post-procedure, patients were promptly transferred to the Intensive Care Unit for close monitoring. Patients underwent a period of fasting, had a gastric tube inserted for gastrointestinal decompression, and received low molecular weight heparin. Once the patient’s condition stabilized, daily administration of either 100 mg aspirin or 75 mg Plavix was initiated. When the patient underwent concurrent aortic valve replacement surgery, warfarin was also administered with dosage carefully adjusted based on the international normalized ratio (INR). Barring cases with specific contraindications or circumstances, warfarin was prescribed as long-term maintenance therapy. After hospital discharge, patients underwent follow-up aortic CTA at 1 month, 6 months, and annually thereafter to ensure continuous monitoring of the patient’s condition and timely identification of any potential complications.

Results

As detailed in Table 1, this study comprised 11 male patients aged 40 to 69 (mean 49.5) years. Time from the onset of symptoms, including abdominal distension and pain, to interventional treatment ranged from 4 to 13 (mean, 6.9) hours. Upon admission, auscultation examinations revealed decreased bowel sounds in 6 patients and a complete absence of bowel sounds in 5 patients (14). Three patients exhibited bloody stools. All patients successfully underwent endovascular treatment of SMA occlusion. Preoperatively, superselective angiography of the mesenteric arteries was performed, and occlusive lesions were identified in all patients. Among the involvement patterns of the SMA, 5 cases were classified as static type, and 6 as mixed type. The dissection lesions affected the middle and distal branches of the SMA. Following emergency endovascular repair procedures, vascular lumen patency was successfully restored. During the endovascular repair procedures of SMA occlusion, a total of 6 coronary stents were implanted: 2 Firebird stents (MicroPort, Shanghai, China), 2 Excel stents (Jiwei, Shandong, China), and 2 Lepu stents (Lepu, Beijing, China). Additionally, 16 peripheral stents were implanted, comprising 13 Zilver stents (COOK, USA) and 3 Smart stents (Johnson & Johnson, USA). Furthermore, 6 carotid artery Precise stents (Johnson & Johnson, USA) were implanted. Mean procedure duration was 1.8 hours, with mean 86.3 milliliters of contrast agent utilized. Following emergency stenting of the SMA, the patients were promptly transferred to the operating room for subsequent ascending aortic replacement surgery. None of the 11 patients developed intestinal necrosis, and all were successfully discharged from the hospital. During follow-up, ranging from 2 to 32 months, none of the patients reported symptoms indicative of mesenteric artery ischemia, such as abdominal pain or distension. Aortic CTA reexamination confirmed the patency and appropriate positioning of the stents within the SMA.

Discussion

Stanford type A aortic dissection, when complicated by acute occlusion of the SMA, constitutes a clinically urgent and critical condition with a poor clinical prognosis. The traditional view is that the rapid restoration of true lumen blood flow can alleviate malperfusion in all distal aortic branches, but the clinical outcomes of immediate proximal aortic repair are suboptimal, and the mortality rate is extremely high. On the one hand, central aortic repair is only effective for dynamic occlusion, but not applicable to static obstruction characterized with thrombosis. On the other hand, SMA ischemia could cause infection, inflammation and metabolic acidosis, also further exacerbate the adversely impact clinical outcomes of open surgical repair. Hence, further in-depth research and deliberation on the optimal management sequence and methodologies for Stanford type A aortic dissection complicated by occlusion of the SMA are warranted.

There are scarce large-scale clinical trial data on Stanford type A aortic dissection complicated by SMA occlusion, with the existing literature predominantly comprising case reports. In 2002, Yamashiro et al. documented a successful case using an iliac artery-to-SMA saphenous vein bypass graft (15). In 2014, Obied et al.’s approach involved the initial implantation of a bare-metal stent in the SMA, followed by an ascending aorta replacement surgery (Bentall procedure). The patient’s postoperative recovery was favorable, and the study claimed this to be the inaugural report of such a surgical procedure in the English literature (2). In the same year, Kato et al. documented two successful comparable cases involving a proximal incision of the SMA, excision of the proximal intimal flap to reinstate blood flow, followed by the Bentall procedure. However, the authors emphasized that this method should be considered as an alternative when endovascular treatment of the SMA is not viable (16). Yang et al. undertook a retrospective analysis of 135 patients with acute Stanford type A aortic dissection complicated by organ malperfusion between 1996 and 2017 (17). Their findings indicated that, in the absence of cardiac tamponade and with stable circulation, prioritizing the restoration of organ blood supply before addressing the ascending aorta is a viable treatment approach. Drawing from these research findings, the 2021 expert consensus from the American Association for Thoracic Surgery advocated for the prioritization of treating organ ischemia as a rational therapeutic choice in the management of Stanford type A aortic dissection complicated by organ ischemia.

In this study, we prioritized the treatment of the SMA affected by dissection in 11 patients prior to performing ascending aorta replacement or combined aortic valve replacement. The rationale for this treatment approach is twofold. Firstly, none of the patients exhibited signs of pericardial effusion in aortic CTA examinations conducted at other medical facilities. Upon admission, their blood pressure remained stable, obviating the need for vasopressor agents. Moreover, they did not present with clinical symptoms of pericardial tamponade, suggestive of a relatively stable circulatory status. Secondly, prior to their transfer to our hospital, all patients not only complained of typical chest and back pain but also reported severe abdominal discomfort and distension. Notably, three patients experienced hematochezia. Upon admission, auscultation of bowel sounds revealed their significant weakening or absence. Additional aortic CTA examinations conducted at other hospitals confirmed that the dissection had compromised the SMA, leading to occlusion of the vessel’s true lumen.

Ascending aorta replacement surgery is a prolonged procedure, typically requiring 6 to 8 hours, particularly when extracorporeal circulation support is indicated. Prolonging the surgery can potentially worsen the already inadequate blood supply to the SMA, thus elevating the risk of postoperative intestinal necrosis. To expedite the restoration of blood flow to the mesenteric artery, we adopted an interventional treatment approach. Following admission, patients were promptly escorted to the interventional suite via a dedicated green channel. Once the true and false lumens were accurately identified, stents were implanted to match the lumen of the SMA, swiftly restoring blood flow to the intestine. This approach effectively salvaged the ischemic bowel and primed the patients for subsequent surgical interventions. Mean procedure duration was 1.8 hours, and when completed, the operating room was promptly prepared to facilitate the patient’s transition to ascending aorta replacement surgery. This approach, however, entails certain risks, particularly ascending aorta rupture, stemming from factors such as perioperative anxiety and pain-induced elevations in blood pressure, intraoperative manipulations of catheters and wires, and heparin administration. It is imperative to establish thorough communication with the patient’s family and secure their informed consent prior to the procedure. Furthermore, it is essential to ensure adequate analgesia for the patient. Through the administration of vasoactive drugs, we maintained the patient’s systolic blood pressure at approximately 100 mmHg. When patients were uncooperative, the anesthesiology department performed intubation and sedation before intervention. During intervention, utmost precautions were taken to prevent catheters and wires from entering the ascending aorta, and heparin use was minimized. Typically, once angiography confirmed the necessity for stenting, we administered 3,000 U of unfractionated heparin to the patient.

Regarding stent selection, our preference was for bare metal stents, although in certain instances, coronary drug-eluting stents were utilized. The stent selection was primarily based on two considerations. Firstly, the patients exhibited Stanford type A aortic dissection with widespread involvement of the entire aorta. In these cases, accessing the true lumen via the upper extremity arteries posed considerable challenges, entailing greater risks, procedural time, and labor intensity. Secondly, our treatment objective for the SMA focused on swiftly restoring its blood supply, rather than preventing arterial rupture. Due to their smaller outer diameter and excellent longitudinal support, self-expandable bare metal stents can adeptly prevent the coverage of the SMA’s branch vessels. When the dissection extends to the vessel’s narrower distal end, conventional peripheral stents may prove unsuitable, rendering coronary drug-eluting stents as a viable option. At mean 13.5 months follow-up, none of the patients reported abdominal pain, bloating, or any other indicators of intestinal ischemia. Upon CTA reexamination of the aorta, the stent retained its integrity and patency.

Early diagnosis plays a pivotal role. Following diagnosis at an external hospital, prompt communication with the cardiac surgery department ensued, leading to the patients’ swift transfer to our facility. Utilizing the CTA data obtained from the referring hospital, we conducted a comprehensive telephone interview to gather information on the patient’s presenting symptoms. The presence of abdominal distension and pain, coupled with stable vital signs, led to prompt activation of the expedited protocol of the chest pain center. Simultaneously, preparations were made in the interventional suite and operating room to facilitate the patients’ direct admission for mesenteric interventional therapy. This streamlined process eliminated redundant procedures, such as repeated aortic CTA exams, thereby considerably decreasing the patients’ hospital waiting time.

Conclusions

Stanford type A aortic dissection, accompanied by SMA occlusion, constitutes a severe condition characterized by exceptionally elevated mortality rates in patients. Hence, clinicians’ early recognition and precise diagnosis of this ailment are paramount. In patients presenting with a stable circulatory status and an absence of pericardial tamponade symptoms, endovascular therapy is preferentially considered as a reliable and efficient approach for swiftly restoring blood flow to the SMA. Nevertheless, the successful execution of this therapeutic strategy hinges on a multidisciplinary team possessing extensive expertise in aortic dissection to guarantee its judicious use and attainment of optimal treatment results.

Acknowledgments

Funding: This study was funded by the Guangzhou Science and Technology Plan Project (No. 202201020441).

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-881/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-881/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-881/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-881/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was approved by the Ethics Committee of The First Affiliated Hospital of Guangzhou Medical University [No. GDREC2018215H(R3)]. All the participants signed a written informed consent form. This study was conducted in accordance with the Helsinki Declaration (as revised in 2013).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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