Optimal Management of Isolated Left Vertebral Artery in Total Arch Replacement With Frozen Elephant Trunk for Aortic Dissection

Abstract

Background

The presence of an isolated left vertebral artery (ILVA) in patients with aortic dissection is a rare and challenging condition. This study aims to determine the optimal management of ILVA in patients with aortic dissection undergoing total arch replacement with frozen elephant trunk.

Methods

This retrospective study enrolled 94 patients with ILVA and aortic dissection who underwent total arch replacement with frozen elephant trunk. Patients were divided into 3 groups: 18 patients underwent ligation of ILVA, 52 underwent ILVA‐left subclavian artery transposition, and 24 underwent ILVA‐left common carotid artery transposition.

Results

Vertebral artery dominance was left dominant in 10.6%, symmetric in 33.0%, and right dominant in 56.4% of patients. Notably, patients who underwent ligation of ILVA had either symmetric or right‐dominant vertebral arteries, with no left‐dominant cases. No strokes were observed. Paraplegia/paraparesis (11.1% versus 11.5% versus 0%, P=0.223), mechanical ventilation time (45 [10–61] hour versus 18 [11–38] hour versus 15 [11–51] hour, P=0.855), and long‐term survival (log‐rank P=0.419) were comparable among the 3 groups. Follow‐up computed tomographic angiography confirmed patency of the left vertebral artery in all patients who underwent ILVA transposition.

Conclusions

Ligation of ILVA, ILVA‐left subclavian artery transposition, and ILVA‐left common carotid artery transposition are all feasible and safe strategies for managing ILVA in patients with aortic dissection undergoing total arch replacement with frozen elephant trunk.

Nonstandard Abbreviations and Acronyms

AD

aortic dissection

ILVA

isolated left vertebral artery

LCCA

left common carotid artery

LSCA

left subclavian artery

TAR with FET

total arch replacement with frozen elephant trunk

Clinical Perspective.

What Is New?

• This study provides the largest case series to date on the management of isolated left vertebral artery (ILVA) in patients with aortic dissection undergoing total arch replacement with frozen elephant trunk, comparing three surgical strategies: ILVA ligation, ILVA‐left subclavian artery transposition, and ILVA‐left common carotid artery transposition.

What Are the Clinical Implications?

• All 3 strategies for managing ILVA in aortic dissection are safe, with similar postoperative outcomes and long‐term survival rates, offering flexible surgical options based on patient‐specific anatomical considerations.

• ILVA ligation, performed in patients with right‐dominant or symmetric vertebral arteries, resulted in shorter cardiopulmonary bypass and cross‐clamp times, with no increase in stroke or spinal cord injury, whereas ILVA transposition ensured long‐term patency of the left vertebral artery.

Aortic dissection (AD) is a life‐threatening cardiovascular disease with an annual prevalence of 3 to 16 cases per 100 000 individuals. ¹ For medical management, AD has a mortality rate of 0.5% per hour and 23.7% at 48 hours, but this decreases to 4.4% with surgical management. ² Total arch replacement with frozen elephant trunk (TAR with FET) has emerged as a major surgical approach for AD involving the aortic arch. ³ This technique has gained favorable results with 10‐year survival rate of 81.4%. ⁴

An isolated left vertebral artery (ILVA) is the left vertebral artery directly arising from the aortic arch, usually between the left common carotid artery (LCCA) and the left subclavian artery (LSCA). ILVA is a congenital aortic arch anomaly with a prevalence of 2.8% to 5.9%. ⁵ , ⁶ , ⁷ , ⁸ The vertebral arteries terminate to form the basilar artery. Mismanagement of ILVA during surgery can lead to posterior circulation stroke or spinal cord ischemia, particularly in patients with an incomplete circle of Willis. ⁹

The coexistence of ILVA and AD, with an incidence of 3.8%, represents a more complex condition and poses significant surgical challenges. ⁸ More rigorous surgical strategies are needed in patients with ILVA and AD, especially the reconstruction of arch vessels. Regarding management of ILVA, our center has adopted 3 approaches including ILVA‐LSCA transposition, ILVA‐LCCA transposition, and ligation of ILVA. However, there is no consensus on the optimal approach for ILVA management during TAR with FET. Previous studies have been limited by small sample sizes. ¹⁰ , ¹¹ , ¹² This study reviewed our experience with ILVA management in patients undergoing TAR with FET for AD, aiming to determine the optimal management of ILVA.

METHODS

Patients

Between January 2015 and February 2024, 116 patients with ILVA and AD who underwent TAR with FET at the Aortic and Vascular Center in Fuwai Hospital were retrospectively enrolled. Exclusion criteria included age <18 years, prior aortic arch replacement, and ILVA combined with other aortic arch anomalies (eg, bovine arch, aberrant right subclavian artery, or right‐sided aortic arch). A total of 94 patients were included in the final analysis. They were divided into 3 groups: 18 patients underwent ILVA ligation, 52 underwent ILVA‐LSCA transposition, and 24 underwent ILVA‐LCCA transposition (Figure 1). This study was approved by the ethics committees of Fuwai Hospital (No. 2023–2061). The requirement for informed consent was waived due to the study's retrospective design. The data that support the findings of this study are available from the corresponding author upon reasonable request.

Figure 1. Flow chart.

AD indicates acute Type A aortic dissection; ILVA, isolated left vertebral artery; LCCA, left common carotid artery; LSCA, left subclavian artery; and TAR with FET, total arch replacement with frozen elephant trunk.

Surgical Procedure

After median sternotomy, the femoral artery, the right axillary artery, and the right atrium were cannulated for cardiopulmonary bypass. During the cooling phase, the operation on the aortic root and ascending aorta was performed as indicated. When the nasopharyngeal temperature reached the target temperature, the lower‐body circulatory arrest began with selective cerebral perfusion. Unilateral cerebral perfusion was through the right axillary artery, while bilateral cerebral perfusion was through the right axillary artery and LCCA. After the aortic arch was transected between the LCCA and the LSCA, a FET stent graft (Cronus, MicroPort Endovascular Shanghai Co, Ltd, China) was inserted into the descending aorta. Subsequently, with its proximal end being clamped, the distal end of a tetrafurcate graft (Terumo, Vascutek Limited, Renfrewshire, UK) was anastomosed to the descending aorta and the FET together. Once the distal arch anastomosis completed, the lower‐body circulatory was restored through the perfusion limb of the tetrafurcate graft. Afterwards, the LCCA was anastomosed to 1 limb of the tetrafurcate graft, and the rewarming phase began. The proximal end of the tetrafurcate graft was anastomosed to the ascending aorta or repaired aortic root, and the innominate artery and the LSCA were anastomosed to the other 2 limbs, respectively.

Regarding the management of ILVA, either ILVA‐LSCA transposition or ILVA‐LCCA transposition was performed after the transposed artery was anastomosed to the tetrafucate graft (Figure 2A and 2B). Ligation of ILVA was performed before the transection of the aortic arch (Figure 2C).

Figure 2. Management of ILVA.

A, Ligation of ILVA. B, ILVA‐LSCA transposition. C, ILVA‐LCCA transposition. ILVA indicates isolated left vertebral artery; LCCA, left common carotid artery; and LSCA, left subclavian artery.

Data Definition and Follow‐Up

Baseline characteristics, imaging findings, intraoperative details, and outcomes were retrospectively collected. Computed tomographic angiography (CTA) was preoperatively performed to confirm the presence of ILVA, its dominance, and associated findings. Left ventricular ejection fraction, aortic regurgitation, and abnormal ventricular wall motion were acquired from echocardiographic reports. Malperfusion syndrome was diagnosed based on clinical symptoms (coma, altered mental status, abdominal pain, sensory or motor dysfunction of extremity), laboratory tests (elevated troponin, liver enzymes, serum creatine, lactate), and imaging evidence (CTA). Thirty‐day mortality was defined as death from any cause occurring within 30 days postoperatively. Other postoperative outcomes were monitored from the time of surgery completion until hospital discharge. Low cardiac output syndrome was defined as requiring intra‐aortic balloon pump insertion, extracorporeal membrane oxygenation support, or ventricular assist device. ¹³ Paraplegia/paraparesis was defined as complete or partial loss of lower limb motor function related to spinal cord ischemia and not related to stroke until hospital discharge. ³

Follow‐up included outpatient visits and telephone consultations, and the last follow‐up was completed in December 2024. For participants remaining event free through December 2024, the censoring time was calculated from the date of surgery completion to December 2024. Individuals who became unavailable for follow‐up before December 2024 were excluded from the Kaplan–Meier analysis. All patients had an aortic CTA at discharge and were recommended to have an aortic CTA at 3 months and annually after surgery.

Statistical Analysis

Continuous variables were expressed as mean±SD or median (the first interquartile, the third interquartile) or median (interquartile range) and assessed with Student's t test or Mann–Whitney U test. Categorical variables were expressed as count (frequency) and compared by chi‐square or Fisher's exact test. Kaplan–Meier analysis was performed to analyze the overall survival among 3 groups. All statistical tests were 2 tailed and P<0.05 was considered statistically significant. Statistical analysis was assessed using R version 4.4.2 (The R Foundation for Statistical Computing, Vienna, Austria).

RESULTS

Baseline Characteristics

Baseline characteristics are presented in Table 1. Acute Type A aortic dissection was present in 88.9%, 84.6%, and 75.0% of patients for ligation of ILVA, ILVA‐LSCA transposition, and ILVA‐LCCA transposition, respectively. One fifth to one third of patients had at least 1 kind of malperfusion syndrome. Vertebral artery dominance was left dominant in 10.6%, symmetric in 33.0%, and right dominant in 56.4% of patients. Notably, no patients with left‐dominant vertebral arteries underwent ligation of ILVA, as our center prospectively excluded these patients from the ligation procedure.

Table 1.

Baseline Characteristics

Variable	All (n=94)	Ligation of ILVA (n=18)	ILVA‐LSCA transposition (n=52)	ILVA‐LCCA transposition (n=24)	P value
Age, y	52±11	52±11	50±11	54±11	0.246
Female sex	19 (20.2%)	2 (11.1%)	9 (17.3%)	8 (33.3%)	0.153
Body mass index	27.5±4.2	27.6±5.4	27.1±3.8	28.2±3.9	0.594
Hypertension	78 (83.0%)	14 (77.8%)	44 (84.6%)	20 (83.3%)	0.800
Hyperlipemia	26 (27.7%)	6 (33.3%)	12 (23.1%)	8 (33.3%)	0.543
Coronary artery disease	18 (19.1%)	2 (11.1%)	8 (15.4%)	8 (33.3%)	0.114
Diabetes	6 (6.4%)	0 (0%)	4 (7.7%)	2 (8.3%)	0.466
Chronic obstructive pulmonary disease	2 (2.1%)	0 (0%)	0 (0%)	2 (8.3%)	0.051
Smoking	34 (36.2%)	8 (44.4%)	20 (38.5%)	6 (25.0%)	0.377
Marfan syndrome	2 (2.1%)	0 (0%)	2 (3.8%)	0 (0%)	0.438
History of cerebrovascular accident	9 (9.6%)	2 (11.1%)	5 (9.6%)	2 (8.3%)	0.955
History of cardiac surgery	3 (3.2%)	2 (11.1%)	1 (1.9%)	0 (0%)	0.095
Acute Type A AD	78 (83.0%)	16 (88.9%)	44 (84.6%)	18 (75.0%)	0.444
Type B AD	4 (4.3%)	2 (11.1%)	2 (3.8%)	0 (0%)	0.206
Malperfusion syndrome	27 (28.7%)	4 (22.2%)	17 (32.7%)	6 (25.0%)	0.627
Cardiac malperfusion	12 (12.8%)	2 (11.1%)	8 (15.4%)	2 (8.3%)	0.674
Cerebral malperfusion	3 (3.2%)	0 (0%)	1 (1.9%)	2 (8.3%)	0.232
Spinal malperfusion	0 (0%)	0 (0%)	0 (0%)	0 (0%)	/
Mesenteric malperfusion	8 (8.5%)	2 (11.1%)	2 (3.8%)	4 (16.7%)	0.160
Renal malperfusion	9 (9.6%)	2 (11.1%)	5 (9.6%)	2 (8.3%)	0.955
Extremity malperfusion	8 (8.5%)	2 (11.1%)	6 (11.5%)	0 (0%)	0.223
Dominance of vertebral artery					0.010
Left vertebral artery dominance	10 (10.6%)	0 (0%)	4 (7.7%)	6 (25.0%)
Right vertebral artery dominance	31 (33.0%)	10 (55.6%)	13 (25.0%)	8 (33.3%)
Symmetric vertebral artery	53 (56.4%)	8 (44.4%)	35 (67.3%)	10 (41.7%)
Ejection fraction (%)	60±5	61±3	60±4	59±7	0.198
Aortic regurgitation (moderate/large)	19 (20.2%)	4 (22.2%)	11 (21.2%)	4 (16.7%)	0.878
Abnormal ventricular wall motion	8 (8.5%)	2 (11.1%)	2 (3.8%)	4 (16.7%)	0.160

Values are presented as mean±SD or count (frequency). AD indicates aortic dissection; ILVA, isolated left vertebral artery; LCCA, left common carotid artery; and LSCA, left subclavian artery.

Intraoperative Data and Postoperative Outcomes

Intraoperative data are shown in Table 2. Almost half of the patients had unilateral antegrade cerebral perfusion, and the other had bilateral antegrade cerebral perfusion both in the total cohort and each group. Concomitant procedures were comparable among groups. Patients who underwent ligation of ILVA had significantly shorter cardiopulmonary bypass time compared with both ILVA‐LSCA and ILVA‐LCCA transposition (147 [134–191] minutes versus 187 [165–211] minutes versus 214 [57–260] minutes, P=0.021). Similarly, the cross‐clamp time was also significantly shorter in patients undergoing ligation of ILVA compared with both ILVA‐LSCA and ILVA‐LCCA transposition (87 [67–115] minutes versus 117 [98–137] minutes versus 122 [88–171] minutes, P=0.002).

Table 2.

Intraoperative Data

Variable	All (n=94)	Ligation of ILVA (n=18)	ILVA‐LSCA transposition (n=52)	ILVA‐LCCA transposition (n=24)	P value
Bentall procedure	8 (8.5%)	0 (0%)	6 (11.5%)	2 (8.3%)	0.319
David procedure	3 (3.2%)	0 (0%)	3 (5.8%)	0 (0%)	0.286
Concomitant coronary artery bypass grafting	17 (18.1%)	2 (11.1%)	9 (17.3%)	6 (25.0%)	0.021
Cerebral perfusion					0.889
Unilateral	51 (54.3%)	10 (55.6%)	29 (55.8%)	12 (50.0%)
Bilateral	43 (45.7%)	8 (44.4%)	23 (44.2%)	12 (50.0%)
Lowest nasopharyngeal temperature (°C)	25.2 (23.1–26.8)	23.1 (20.1–26.7)	25.3 (23.9–26.9)	25.7 (24.9–26.7)	0.889
Cardiopulmonary bypass time (min)	185 (149–216)	147 (134–191)	187 (165–211)	214 (157–260)	0.021
Cross‐clamp time (min)	116 (88–137)	87 (67–115)	117 (98–137)	122 (88–171)	0.002

Values are presented as mean ±SD, median (the first quartile, the third quartile), or count (frequency). ILVA indicates isolated left vertebral artery; LCCA, left common carotid artery; and LSCA, left subclavian artery.

Postoperative outcomes are presented in Table 3. Thirty‐day mortality was 11.1% (2/18), 5.8% (3/52), and 8.3% (2/24) for patients receiving ligation of ILVA, ILVA‐LSCA transposition, and ILVA‐LCCA transposition, respectively (P=0.744). No patient had stroke. Paraplegia/paraparesis was observed in 11.1% (2/18), 11.5% (6/52), and 0% of patients for ligation of ILVA, ILVA‐LSCA transposition, and ILVA‐LCCA transposition (P=0.223). Mechanical ventilation time, intensive care unit stay, and hospital stay were comparable among groups.

Table 3.

Postoperative Outcomes

Variable	All (n=94)	Ligation of ILVA (n=18)	ILVA‐LSCA transposition (n=52)	ILVA‐LCCA transposition (n=24)	P value
30‐d mortality	7 (7.4%)	2 (11.1%)	3 (5.8%)	2 (8.3%)	0.744
Stroke	0 (0%)	0 (0%)	0 (0%)	0 (0%)	/
Paraplegia/paraparesis	8 (8.5%)	2 (11.1%)	6 (11.5%)	0 (0%)	0.223
Reexploration for bleeding	1 (1.1%)	0 (0%)	1 (1.9%)	0 (0%)	0.665
Continuous renal replacement therapy	12 (12.8%)	4 (22.2%)	4 (7.7%)	4 (16.7%)	0.226
Low cardiac output syndrome	0 (0%)	0 (0%)	0 (0%)	0 (0%)	/
Mechanical ventilation time, h	16 (11–54)	45 (10–61)	18 (11–38)	15 (11–51)	0.855
Intensive care unit stay, d	3 (2–5)	5 (1–10)	3 (2–5)	3 (2–6)	0.861
Hospital stay, d	10 (9–14)	12 (9–14)	10 (9–14)	11 (9–14)	0.719

Values are presented as median (the first quartile, the third quartile), or count (frequency).

Follow‐Up Period

The median follow‐up period was 2.6 (1.3–5.6) years with a follow‐up completeness of 96.8%. Three patients were lost to follow‐up. Six late deaths occurred during follow‐up. Kaplan–Meier curves showed no significant difference among the three groups (log‐rank P=0.419) (Figure 3). One‐year and 3‐year survival rates were 88.9% and 77.9% for patients with ligation of ILVA, 92.1% and 89.6% for patients with ILVA‐LSCA transposition, and 90.9% and 77.9% for patients with ILVA‐LCCA transposition, respectively. Three patients underwent a 2‐stage thoracoabdominal aortic repair for unsuccessful distal aortic remodeling.

Figure 3. Kaplan–Meier analysis estimating overall survival among patients receiving ligation of ILVA, ILVA‐LSCA transposition, and ILVA‐LCCA transposition.

ILVA indicates isolated left vertebral artery; LCCA, left common carotid artery; and LSCA, left subclavian artery.

Postoperative or follow‐up CTA was performed on 85.1% of patients (80/94) at our center with a median period of 4.4 (0.6–20.2) months. Occlusion of the left vertebral artery was observed in 15.0% (12/80) of patients, all of whom received ligation of ILVA (Figure 4A). In contrast, all patients with transposed ILVA retained a patent left vertebral artery (Figure 4B and 4C).

Figure 4. A, Follow‐up CTA of a patient undergoing ligation of ILVA. B, Follow‐up CTA of a patient undergoing ILVA‐LSCA transposition. C, Follow‐up CTA of a patient undergoing ILVA‐LCCA transposition.

CTA indicates computed tomographic angiography; ILVA, isolated left vertebral artery; LCCA, left common carotid artery; and LSCA, left subclavian artery.

DISCUSSION

This study represents the largest case series to date on the surgical management of ILVA in patients with AD, providing significant insights into optimal treatment strategies. Our findings indicate that approximately 50% of patients with AD exhibit symmetric vertebral arteries, and 10% present with left‐dominant vertebral arteries. ILVA ligation was exclusively performed in patients with symmetric or right‐dominant vertebral arteries, resulting in reduced cardiopulmonary bypass and cross‐clamp times. Thirty‐day mortality, paraplegia/paraparesis, mechanical ventilation time, and long‐term survival were comparable among 3 groups. No patients had stroke. All patients who underwent ILVA transposition showed patent left vertebral artery in follow‐up CTA.

Various centers have reported differing approaches to ILVA management in patients with AD. Zhu et al. anastomosed the ILVA to the LSCA or its graft branch, noting a 5% incidence of stroke or delirum. ¹⁴ Qi et al. employed ILVA‐LSCA or ILVA‐LCCA transposition, reporting a 10% rate of spinal cord injury (all recovered during follow‐up) and a 5% rate of transient neurological deficits (resolved before discharge). ¹² Zuo et al. introduced a novel approach involving prior ILVA‐LCCA transposition under normothermic off‐pump conditions, achieving no neurological complications. ¹⁰ Zhu et al. used the stented elephant trunk technique, offering an alternative for those lacking a suitable proximal landing zone for thoracic endovascular aortic repair. ¹¹ In our center, we employed 3 distinct strategies for ILVA management: ligation, ILVA‐LSCA transposition, and ILVA‐LCCA transposition. Our analysis revealed no significant differences among these approaches concerning adverse events such as stroke, paraplegia/paraparesis, mechanical ventilation time, and long‐term survival. These findings suggest that all 3 methods are viable options in TAR with FET for patients with AD and ILVA.

The indications for each management strategy of ILVA were determined based on multiple factors. First, the decision to ligate the ILVA largely depended on its diameter Cases with thin‐walled ILVA and either right‐dominant vertebral arteries or symmetric vertebral arteries were considered for ligation. Patients with left vertebral artery dominance, accounting for 10% of our cohort and consistent with previous research on ILVA in Type B AD, ¹⁵ were treated with either ILVA‐LSCA or ILVA‐LCCA transposition. Second, if the LSCA or LCCA was involved in the dissection, transposition was not considered. Third, the anatomical relationship among the arch vessels further influenced the strategy, as a shorter distance between the transposed artery and the ILVA was preferred.

Patients undergoing ILVA transposition in our cohort maintained long‐term vessel patency. Considering that vertebral arteries supply critical posterior brain structures, ¹⁶ and given the lower incidence of a complete circle of Willis in the Chinese population, ¹⁷ ILVA ligation could theoretically elevate the risk of postoperative stroke or spinal cord injury. However, our comparable outcomes across these three management approaches might be attributed to the reduced cardiopulmonary bypass times in the ligation group. Previous research indicated that prolonged cardiopulmonary bypass time was associated with postoperative stroke in TAR with FET. ¹⁸ In addition, in patients with symmetric or right‐dominant vertebral arteries, the right vertebral artery likely compensates adequately for the absence of the left, mitigating potential complications.

Limitations

This was a retrospective study from a single‐center experience, which might introduce selection bias and limit generalizability. Although the follow‐up rate was high, the relatively short median follow‐up period may not fully capture long‐term complications and survival trends. Future multicenter, prospective studies with longer follow‐up durations are needed to validate these results.

CONCLUSIONS

Ligation of ILVA, ILVA‐LSCA transposition, and ILVA‐LCCA transposition are all feasible and safe strategies for managing ILVA in patients with AD undergoing TAR with FET. These findings provide valuable guidance for surgical decision‐making in this complex patient population.

Sources of Funding

Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (CIFMS) (No. 2021‐I2M‐1‐027 and No. 2022‐I2M‐C&T‐B‐036).

Disclosures

None.