Outcomes of surgical management for Kommerell’s diverticulum associated with type B aortic dissection

Abstract

OBJECTIVES

Kommerell’s diverticulum presents a distinctive challenge in clinical management due to its rarity and diverse clinical manifestations, particularly when concurrent with type B aortic dissection. However, a consensus on the optimal treatment strategy has yet to be established. This study presents our experience with an open surgical approach to treating Kommerell’s diverticulum associated with type B aortic dissection.

METHODS

This retrospective study evaluated 10 patients who underwent surgical repair for Kommerell’s diverticulum with concurrent type B aortic dissection. Through median sternotomy, under cardiopulmonary bypass and deep hypothermic circulatory arrest + retrograde cerebral perfusion, a frozen elephant trunk stent graft was deployed in the descending thoracic aorta to address the type B aortic dissection and Kommerell’s diverticulum. Aberrant subclavian arteries were reconstructed by bypassing the distal portion into the native ascending aorta or carotid artery, accompanied by proximal ligation of the aberrant artery.

RESULTS

The median age of the patient was 49 years (interquartile range: 42.2–58.5). There were no in-hospital or 30-day postoperative deaths. All patients were discharged with a median hospital stay of 8.5 days (interquartile range: 7.75–10.5). No cases of stroke or spinal cord ischaemia were observed. Follow-up was completed for all patients, with a mean duration of 27.4 (standard deviation: 15.3) months, during which no adverse events occurred.

CONCLUSIONS

This surgical approach for managing Kommerell’s diverticulum with type B aortic dissection offers a safe and effective option, yielding favourable short-term outcomes. It may provide a durable alternative to traditional surgical methods and overcome limitations associated with endovascular surgeries.

In 1936, the pioneering German radiologist, Dr Burckhard Friedrich Kommerell, identified an aortic diverticulum giving rise to an aberrant right subclavian artery (ARSA) [1].

Graphical abstract

INTRODUCTION

In 1936, the pioneering German radiologist, Dr Burckhard Friedrich Kommerell, identified an aortic diverticulum giving rise to an aberrant right subclavian artery (ARSA) [1]. Beyond this seminal observation, the terminology ‘Kommerell’s diverticulum’ (KD) has evolved to encompass a diverticulum located at the proximal descending aorta, leading to the emergence of an aberrant subclavian artery (ASA), often referred to as ‘Arteria lusoria’ [1]. The left‐sided aortic arch with an ARSA is relatively more common with an approximate incidence of 0.7–2.0%, while the right‐sided aortic arch with an aberrant left subclavian artery is less prevalent with an approximate incidence of 0.04–0.4% [2, 3]. A substantial percentage, ranging from 20% to 60%, of individuals with aberrant right or left subclavian arteries exhibit an association with KD [4, 5]. In most instances, KD with ASA is an asymptomatic congenital malformation often incidentally discovered during chest computed tomography (CT) scans conducted for unrelated reasons or during assessments for other diseases. Symptoms are reported to occur in ∼5% of patients and are most commonly due to compression of the trachea or the oesophagus [6]. Histological anomalies contribute to the vulnerability of the aortic wall adjacent to the diverticulum, leading to dissection or rupture [7, 8]. Literature reviews indicate varying rates of rupture or dissection associated with KD, with Austin and Wolfe reporting 19% [7] and Cinà et al. noting 53% [9].

Managing KD with aortic dissection poses a formidable challenge; currently, no specific guidelines are available [10]. Treatment options include open surgical repair, hybrid endovascular repair and thoracic endovascular aortic repair (TEVAR) [7, 9, 11, 12]. Although TEVAR has become popular, it has shortcomings such as endoleak, retro-tear and the need for reintervention, which may lead to poor long-term results [13]. The choice depends on the individual patient’s age, symptoms, presentation acuity and lesion morphology.

This study aims to summarize our centre’s experience in the surgical management of KD concurrent with type B aortic dissection (TBAD), delving into the therapeutic strategies employed. We specifically outline our preferred technique, which involves open surgical repair of TBAD and KD using frozen elephant trunk (FET) stent graft and reconstruction of ASA.

PATIENT AND METHODS

Ethical statement

Data collection and analysis for this study were approved by the Institutional Review Board (IRB No. 202403080) of Xiangya Hospital, Central South University. The requirement of informed patient consent was waived. This study aligns with the current clinical practice guidelines where applicable.

Patient selection

Between October 2019 and November 2023, a total of 10 consecutive patients diagnosed with KD associated with TBAD underwent surgical treatment. The diagnosis was made based on history, clinical presentation and imaging assessments.

All patients underwent preoperative assessments, including computed tomography angiography scans, to confirm the diagnosis of TBAD and KD. These scans also evaluated the origin and pathway of the ASA through the mediastinum (Figs 1 and 2; Video 1). In these cases, the ASA was found to originate from either the aortic arch or the descending thoracic aorta. KD was confirmed when the ASA orifice diameter exceeded 1.5 times the diameter of the distal segment. The ARSA typically coursed across the superior mediastinum, passing behind the trachea and oesophagus to the contralateral side.

Figure 1:

Preoperative images (A–D) depicting the aberrant subclavian artery, Kommerell’s diverticulum and type-B aortic dissection

Figure 2:

Illustration depicting the anatomy of aberrant right subclavian artery with Kommerell’s diverticulum and type B aortic dissection; oesophagus (1), trachea (2), right common carotid artery (3), left common carotid artery (4), left subclavian artery (5), aberrant right subclavian artery (6), type B aortic dissection with intimal tear (7) and ascending aorta (8)

The primary indication for surgical repair in this group of patients was the presence of KD with ASA. Another crucial reason for intervention was to prevent rupture and malperfusion of distal organ systems due to acute, uncomplicated TBAD. In one case, severe malperfusion of the left lower limbs was observed. The primary outcomes assessed in this study included perioperative mortality, postoperative stroke, spinal cord injury and renal dysfunction.

Temperature management was critical for cerebral protection in our patient group and was carefully monitored and controlled throughout the procedure. Cerebral near-infrared spectroscopy was used to monitor regional cerebral oxygen saturation, while Bi-spectral Index monitoring was employed to confirm adequate cooling.

Surgical technique

Surgical access involved a full median sternotomy for all patients. Cardiopulmonary bypass (CPB) was initiated using cannulation of the ascending aorta, inferior vena cava and superior vena cava, along with the placement of a catheter in the right superior pulmonary vein for left heart drainage. Once CPB was initiated, systemic cooling was commenced to induce hypothermia. A snare thread was positioned around the superior vena cava (above the Azygos vein take-off) for retrograde cerebral perfusion (RCP). The aorta was cross-clamped, and a 4°C ‘Del Nideo’ cardio-protective solution was antegradely delivered. During the cooling time, the ASA was identified and mobilized under the trachea and oesophagus and isolated in the posterior mediastinum on the right side of the trachea above the level of tracheal bifurcation and was subsequently snared. Once the nasopharyngeal temperature reached 20°C, deep hypothermic circulatory arrest with RCP was implemented, with the aortic clamp removed post circulatory arrest. The RCP was initiated at a rate of 5–10 ml/kg/min at a perfusate temperature of 20°C, and central venous pressure was maintained not exceeding 25 mmHg.

A meticulous oblique incision, originating from the anterior wall of the distal aortic arch and extending to the orifice of the left subclavian artery, allowed access to the diverticulum segment and dissection. The descending aorta’s lumen was carefully inspected to identify the intimal tear and secure the true lumen. An appropriately sized self-expandable FET stent graft ‘Cronus’ (the patient cohort received a 10 cm length FET stent graft, with diameters ranging from 24 to 28 mm) was delivered, transitioning from a bound, compressed state to its expanded form within the true lumen. The graft was slightly bent to conform to the arch curvature before insertion into the proximal descending aorta. After the successful implantation and fixation of the FET stent graft, its proximal end was secured to the aortotomy incision line situated in zone 2 with a continuous 4–0 polypropylene suture. This step effectively addressed the dissected aortic segment and prevented type IA endoleak. No arch replacement was performed in this patient group as the aortic arch was normal, and there was no pathology or dissection extension into the aortic arch. Subsequently, the aortotomy in zone 2 proximal to the diverticulum segment was sutured using continuous stitches of 4–0 polypropylene (Fig. 3) (Please refer to Videos 2 and 3 for details on further elucidation of the described surgical technique). After completion of the anastomosis, air evacuation was meticulously conducted in the Trendelenburg position, RCP was halted and normal CPB was reinstated.

Figure 3:

(A–C) Intraoperative images showing the proximal fixation of the frozen elephant trunk stent using a 4–0 Prolene suture

In all the cases, the reimplantation or bypass of ASA was performed during the rewarming phase. The reconstruction of ASA was tailored to the specific pathology. Upon completion of rewarming, CPB was halted, heparin reversal was performed, cannulas were removed and haemostasis was achieved. The remaining steps of the operation mirrored standard cardiac procedures.

Statistical analysis

Continuous variables were presented as mean and standard deviation for normally distributed data, and as median with interquartile range (IQR) for skewed data, while categorical variables were represented as frequencies (n) and percentages (%). Statistical analysis was conducted utilizing the SPSS V-26 software package.

RESULTS

Baseline and preoperative characteristics

The median age at presentation was 49 years (IQR: 42.2–58.5 years), with an equal male-to-female ratio of 1:1. Eight patients presented with an ARSA, while two patients had an aberrant left subclavian artery. For a summary of all patients, please refer to Table 1. Preoperative CT scans are provided in Fig. 1 as well as Video 1.

Table 1:

Baseline characteristics of patients, including demographic information and preoperative conditions

Age	Gender	BMI (kg/m2)	Diagnosis
46	Female	30.8	KD + ALSA + TBAD
52	Female	19	KD + ARSA + TBAD
57	Male	26	KD + ARSA + TBAD
63	Male	23.5	KD + ARSA + TBAD
65	Male	25	KD + ARSA + TBAD
53	Female	23.8	KD + ARSA + TBAD
45	Male	28.5	KD + ALSA + TBAD
31	Male	30	KD + ARSA + TBAD + Left lower limb malperfusion.
34	Female	29.7	KD + ARSA + TBAD
45	Female	30	KD + ARSA + TBAD

ARSA: aberrant right subclavian artery; ALSA: aberrant left subclavian artery; BMI: body mass index; KD: Kommerell’s diverticulum; TBAD: type B aortic dissection.

Intraoperative data

The median duration of CPB was 150.5 min (IQR: 137.5–182.7 min), and the median duration of RCP was 39.5 min (IQR: 36.5–51.5 min) (refer to Table 2 for detailed intraoperative data). The lowest bladder temperature, maintained at 20°C, indicated the use of deep hypothermic circulatory arrest, with additional cerebral protection provided by RCP. FET implantation was performed in all patients (Figs 4 and 5).

Table 2:

Intraoperative details along with postoperative data

Surgical procedures	CPB time	RCP time	Postoperative hospital stays
FET stent graft + LSA to LCCA bypass	130	37	7
FET stent graft + RSA reimplanted to AA	115	41	8
FET stent graft + RSA reimplanted to AA	180	50	9
FET stent graft + RSA reimplanted to AA	140	48	8
FET stent graft + RSA reimplanted to AA	160	56	12
FET stent graft + RSA to RCA bypass	140	37	9
FET stent graft + LSA to LCA bypass	194	56	13
FET stent graft + RSA reimplanted to AA + Ascending aorta to left femoral artery bypass graft.	191	33	10
FET stent graft + RSA reimplanted to AA	155	35	8
FET stent graft + RSA reimplanted to AA	146	38	7

AA: ascending aorta, RSA; aberrant right subclavian artery, LSA; aberrant left subclavian artery, RCA; right carotid artery, LCA; left carotid artery, FET; frozen elephant trunk, CPB; cardiopulmonary bypass, RCP; retrograde cerebral perfusion.

Figure 4:

Illustration depicting the surgical procedures performed, including the implantation of a frozen elephant trunk stent graft, and the reconstruction of the aberrant subclavian artery in a patient with Kommerell’s diverticulum and type B aortic dissection; oesophagus (1), trachea (2), right common carotid artery (3), left common carotid artery (4), left subclavian artery (5), aberrant right subclavian artery reimplantation into ascending aorta (6), frozen elephant trunk stent graft implantation into descending aorta (7) and ascending aorta (8)

Figure 5:

(A) Postoperative CT image displaying the successful implantation of the frozen elephant trunk stent graft. (B) Reconstruction of the aberrant subclavian artery via bypass to the right carotid artery (red arrow). (C) Reconstruction of the aberrant subclavian artery via reimplantation into a native ascending aorta (red arrow) and an extra-anatomic ascending aorta-to-left femoral artery bypass (blue arrow) in a patient with left lower limb malperfusion

In seven cases, ARSA was reimplanted into the native ascending aorta using an 8 mm Dacron graft, while in one case, it was bypassed directly to the right carotid artery. The two cases with an aberrant left subclavian artery were bypassed to the left carotid artery. In one patient with left femoral artery malperfusion, an extra-anatomic bypass from the ascending aorta to the left femoral artery was performed after persistent malperfusion was observed, despite surgical aortic repair. The proximal segment of the ASA was ligated and sutured. There were no intraoperative deaths reported in this study.

Postoperative details

Postoperatively, one case required chest re-exploration due to bleeding. None of the patients suffered complications such as stroke, spinal cord injury or renal dysfunction. All patients were discharged, with a median hospital stay of 8.5 days (IQR: 7.75–10.5 days) (Table 2). Notably, there were no in-hospital or 30-day postoperative deaths within our patient group, further attesting to the favourable outcomes associated with this technique. No abnormal CT manifestations (Figure 5; Video 4) or clinical events were found in all these patients.

Following hospital discharge, patients resumed their regular activities and received antihypertensive medication as part of their postoperative regimen. All the patients were advised to attend regular outpatient appointments at 1, 3, 6 and 12 months, followed by annual check-ups. All patients were monitored for a mean of 27.4 (standard deviation: 15.3) months (ranging from 6 to 50 months), during which they underwent regular postoperative imaging (computed tomography angiography) and echocardiograms.

Throughout the follow-up period, none of the patients developed endoleak or distal stent graft-induced new entry, nor did they require reoperation due to primary aortic pathology or failure of the surgical procedures. Follow-up computed tomography angiography scans showed no perfusion of KD, negative aortic remodelling or graft kinking. Additionally, no mortality was observed during the follow-up period, indicating the sustained well-being of the patients after surgical intervention.

DISCUSSION

KD presents a distinctive challenge in clinical management due to its rarity and diverse clinical manifestations, especially when concurrent with TBAD. Histological findings of cystic medial necrosis in the diverticulum wall have enhanced our understanding of the high rates of aortic dissection and rupture associated with this anomaly [7, 8]. The substantial risk of aortic dissection, reported to exceed 50% in KD cases [9, 14], emphasizes the urgency for effective treatment.

Advances in CT angiography have improved the diagnosis of KD, enabling more comprehensive evaluations of management strategies [9, 15]. Various surgical approaches have been documented [9, 16], with historical mortality rates ranging from 8.3% to 18% [7, 9], reflecting the complexity of these interventions. Although operative outcomes have improved [17, 18], the anatomical challenges of KD repairs remain significant. However, growing surgical experience has reduced the risks associated with open procedures for KD with TBAD [13, 19].

While TEVAR has emerged as an alternative treatment, it often necessitates reinterventions [20], particularly concerning for younger patients with longer life expectancies. TEVAR is also associated with technical challenges, such as sealing effectiveness and aneurysm exclusion, leading to uncertain long-term outcomes [9, 13]. The absence of a standardized treatment approach for KD, especially in cases involving concurrent TBAD, likely stems from the significant anatomical variability encountered in individual patients.

Historically, the management of uncomplicated TBAD (Unco-TBAD) has focused on optimal Medical Therapy, emphasizing blood pressure and heart rate control [21]. Surgical intervention was reserved for cases with evolving complications [22]. While optimal Medical Therapy yielded excellent short-term outcomes, its long-term efficacy was limited, leading to a transition to a complicated TBAD [23]. Recent studies highlight the survival benefits of aortic intervention over optimal Medical Therapy alone, particularly in acute, Unco-TBAD cases [24].

In uncomplicated KD without TBAD, early surgical intervention is generally recommended due to the catastrophic consequences of rupture [25]. The clinical relevance of KD is further underscored by the mortality risks from rupture, morbidity due to compression of mediastinal structures and the inherent surgical complexity [9], emphasizing the need for a more defined and standardized treatment strategy.

Our approach, which combines traditional open surgery principles with advanced interventional techniques, presents a feasible and reproducible method for repairing KD associated with TBAD. The use of a ‘Cronus’ FET stent graft, deployed under deep hypothermic circulatory arrest and RCP, enabled precise elimination of pathology under direct visual control, reducing risks such as endoleak and stent graft dislocation. The ‘Cronus’ Surgical Stent-Graft System, developed by Shanghai MicroPort Medical (Group) Co., Ltd, is primarily used in thoracic surgery for DeBakey I and DeBakey III aortic dissections. It offers a significant improvement in the safety and convenience of complex thoracic aortic surgery, reducing morbidity and mortality rates [26]. Long-term outcomes, such as durability in type A aortic dissection, have also been demonstrated [27]. Unlike purely endovascular stent grafts (utilized in TEVAR), the ‘Cronus’ stent graft differs in graft material and design. It comprises a regular Dacron vascular tube with interconnected Z-shaped expandable stents. At the proximal and distal ends, there is an additional centimetre of Dacron sewing cuff, facilitating conventional hand-sewn anastomosis. Additionally, the ‘Cronus’ FET stent graft can be directly anastomosed during subsequent distal aorta repair, if necessary.

Early open surgical repair may offer substantial benefits for patients with acute Unco-TBAD, potentially preventing complications such as rupture and malperfusion. In this approach, the placement of the ‘Cronus’ FET stent graft successfully occluded the ASA origin and replaced the aortic diverticulum segment, thereby enhancing procedural safety. The FET stent graft has become an increasingly utilized option for repairing distal aortic arch and proximal descending aortic pathologies [28]. We also reconstructed the ASA to preserve perfusion to the cerebral and arm regions and fully address the KD pathology. The current consensus favours reconstructing or relocating the ASA in adults to prevent issues like upper limb ischaemia or the subclavian steal phenomenon, which can occur with simple ligation [29]. For younger patients, complete anatomical correction is considered the best approach to ensure long-term positive outcomes. This comprehensive strategy effectively manages the complexities of KD with TBAD, offering a patient-specific solution. We suggest that this technique will lead to better long-term results, reducing the risks and complications associated with traditional surgical methods and TEVAR.

Limitations

This study has several limitations, including its descriptive nature, observational design, small sample size—which, while suitable for sharing our centre’s experience, limits the generalizability of findings—and the short follow-up period, which represents a defect in assessing long-term outcomes. These factors make it challenging to draw robust conclusions about the procedure’s effectiveness and safety, particularly regarding mid- and long-term outcomes. While our experience supports this approach as optimal, further validation through larger, multi-institutional cohorts and extended long-term follow-up is essential to confirm its reliability and efficacy.

CONCLUSION

In conclusion, treating KD associated with TBAD is a complex challenge that requires thoughtful consideration of treatment options. Our study highlights the difficulties and outcomes related to this rare condition, suggesting a surgical approach that shows promising results. This technique offers a safe and dependable option that adds to the existing methods for treating patients with this pathology.

Glossary

ABBREVIATIONS

ARSA

Aberrant right subclavian artery

ASA

Aberrant subclavian artery

CPB

Cardiopulmonary bypass

CT

Chest computed tomography

CVP

Central venous pressure

FET

Frozen elephant trunk

IQR

Interquartile range

KD

Kommerell’s diverticulum

RCP

Retrograde cerebral perfusion

TBAD

Type B aortic dissection

TEVAR

Thoracic endovascular aortic repair

FUNDING

This work was supported by a grant from the Scientific Research Program of FuRong Laboratory (No. 2023SK2093-2).

Conflict of interest: Research Grant: This work was supported by a grant from the Scientific Research Program of FuRong Laboratory (No. 2023SK2093-2).

DATA AVAILABILITY

The data supporting this study’s findings are available on request from the corresponding author.

ETHICAL APPROVAL

Data collection and analysis for this study were approved by the Institutional Review Board (IRB No. 202403080) of Xiangya Hospital, Central South University. The requirement of informed patient consent was waived.

Author contributions

Nouman Ahmad: Data curation; Formal analysis; Investigation; Writing—original draft. Lingjin Huang: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Resources; Supervision; Validation; Visualization; Writing—review & editing. Xuliang Chen: Data curation; Formal analysis; Investigation; Writing—review & editing. Yingjie Huang: Data curation; Investigation. Jiawei Li: Data curation; Investigation. Zhongshang Xie: Data curation; Investigation.

Reviewer information

Interdisciplinary CardioVascular and Thoracic Surgery thanks Kamran Ahmadov, Moustafa Farouk and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.