Central nervous injury risk factors after endovascular repair of a thoracic aortic aneurysm with type B aortic dissection

Abstract

BACKGROUND

Aortic dissection is the deadliest disease of the cardiovascular system. Type B aortic dissection accounts for 30%-60% of aortic dissections and is mainly treated by endovascular repair of thoracic endovascular aneurysm repair (TEVAR). However, patients are prone to various complications after surgery, with central nervous system injury being the most common, which seriously affects their prognosis and increases the risk of disability and death. Therefore, exploring the risk factors of central nervous system injury after TEVAR can provide a basis for its prevention and control.

AIM

To investigate the risk factors for central nervous system injury after the repair of a thoracic endovascular aneurysm with type B aortic dissection.

METHODS

We enrolled 306 patients with type B aortic dissection who underwent TEVAR at our hospital between December 2019 and October 2022. The patients were categorized into injury (n = 159) and non-injury (n = 147) groups based on central nervous system injury following surgery. The risk factors for central nervous system injury after TEVAR for type B aortic dissection were screened by comparing the two groups. Multivariate logistic regression analysis was performed.

RESULTS

The Association between age, history of hypertension, blood pH value, surgery, mechanical ventilation, intensive care unit stay, postoperative recovery times on the first day after surgery, and arterial partial pressure of oxygen on the first day after surgery differed substantially (P < 0.05). Multivariate logistic regression analysis indicated that age, surgery time, history of hypertension, duration of mechanical ventilation, and intensive care unit stay were independent risk factors for central nervous system injury after TEVAR of type B aortic dissection (P < 0.05).

CONCLUSION

For high-risk patients with central nervous system injury after TEVAR of type B aortic dissection, early intervention measures should be implemented to lower the risk of neurological discomfort following surgery in high-risk patients with central nervous system injury after TEVAR for type B aortic dissection.

Key Words: Plateau area, Type B aortic dissection, Thoracic endovascular aneurysm repair, Central nervous system injury, Risk factors

Core Tip: This study found that age, surgical time, history of hypertension, duration of mechanical ventilation, and length of intensive care unit stay were independent risk factors for central nervous system injury after thoracic endovascular aneurysm repair. By identifying patients with a higher risk of central nervous system injury after type B coarctation with intrathoracic hemangioma repair early, clinicians can facilitate optimal diagnosis and treatment, thereby reducing the associated mortality and improving the quality of life.

INTRODUCTION

Aortic dissection is now recognized as one of the deadliest and most common diseases of the cardiovascular system. It occurs because of a tear in the inner lining of the aorta and is marked by an abrupt onset and rapid progression. Aortic dissection involves many tissue systems and is associated with complex complications. The high rate of condition-related deaths seriously jeopardizes the survival rate[1,2]. The incidence rate of aortic dissection has been reported to be 2–3.5 cases per 10000 people and is increasing annually. If patients with aortic dissection are not treated in time, the mortality rate 6–24 hours after onset is 22.7%–50%, and within one week, is as high as 68%[2]. Proximal rupture of type B aortic dissection occurs in the descending thoracic aorta and the following arteries, accounting for 30%–60% of aortic dissections[3,4]. With continuous improvements in endovascular technology, thoracic endovascular aneurysm repair (TEVAR) has emerged as a first-line therapy for type B aortic dissection and can reduce the mortality rate of patients from 31% to 17%. However, the complex surgical procedure and varied pathological anatomy of aortic dissection can increase the frequency of complications following surgery, where the incidence of postoperative central nervous system injury is the highest. This can cause temporary or permanent neurological damage in patients, severely affecting their prognosis and increasing their risk of disability and death[5,6]. The causes and mechanisms of central nervous system injury after TEVAR of type B aortic dissection are unclear. Exploring the factors related to postoperative central nervous system injury may help improve clinical outcomes and promote a better patient prognosis. Therefore, this study explored the risk factors for central nervous system injury in patients with type B aortic dissection after TEVAR and provided a relevant basis for preventing and controlling this injury in patients during the perioperative period.

MATERIALS AND METHODS

Study subjects

We enrolled 306 patients with type B aortic dissection who underwent TEVAR at our institution between December 2019 and October 2022. Individuals were categorized into two groups based on whether central nervous system injury occurred following surgery: Those with injuries (n = 159) and those without (n = 147). The non-injury group contained 29 females and 118 males, whereas the injury contained 36 females and 123 males; the body mass index (BMI) was 24.16 ± 2.15 and 24.23 ± 2.66 for the non-injury and injury groups, respectively. The sex and BMI of both categories did not differ significantly (P > 0.05). The inclusion criteria were as follows: (1) Patients with type B aortic dissection with a normal ascending aorta and aortic arch and rupture in the descending aorta; (2) patients receiving TEVAR; and (3) patients who were informed and voluntarily participated in this study. The exclusion criteria were as follows: (1) Malignant tumors and other diseases; (2) penetrating atherosclerotic ulcer, aortic intramural hematoma, or true or false aortic aneurysm; and (3) ulcer-like protrusion, traumatic aortic dissection, residual dissection of the descending aorta after ascending aorta replacement, Marfan syndrome, or other combinations of connective tissue disorders, such as Ehlers-Danlos syndrome.

Diagnostic criteria

(1) Echocardiography showed no dissection, ascending aortic intimal valve, or valve disease; (2) The main diagnostic method was aortic digital computed tomography angiography (CTA), which was used to determine the location and extent of the aortic dissection, formation of false lumen thrombosis, or presence of branch artery involvement; and (3) Digital subtraction angiography was used to determine the location of the primary rupture, the scope of aortic coarctation, and blood supply to the branch arteries.

Treatment methods

All patients were administered general anesthesia. The diameter of the covered stent was selected according to the diameter of the thoracic aorta near the opening of the left subclavian artery on preoperative CTA and was increased by 10%–15%. The distance from the first aortic rupture to the opening (proximal anchoring area) was > 15 mm. When the distance from the anchoring area was inadequate, the left subclavian artery was occluded according to the patient’s condition, and artificial vascular bypass was performed using the left subclavian artery and left common carotid artery chimney techniques: (1) The unilateral or bilateral femoral arteries were exposed, an inguinal incision was made, and a sheath was inserted through the femoral artery puncture; (2) After systemic heparinization, a guidewire and catheter were used together to enter the ascending aorta through the true lumen of the aortic dissection. The location of the aortic rupture, the scope of the anchoring area, and arterial blood supply to the abdominal visceral branches were determined using aortography; (3) After an exchange of the super-stiff guidewire and reasonable control of the systolic blood pressure, the covered stent system was implanted through the femoral artery to the marked position of the thoracic aorta. A stent was then placed, restoring the blood pressure to normal; (4) Aortic angiography was performed again to determine the isolation of aortic rupture, whether internal leakage or vascular remodeling had occurred, the blood flow of the head blood vessels, and the arterial blood supply of each branch. If the patient had stenosis of the visceral artery or true lumen of the lower extremity artery after surgery, a bare stent was placed in the branch artery. If obvious internal leakage occurred on postoperative angiography, balloon dilatation or secondary implantation of the covered stent was performed according to the patient’s condition. If the patient had partial true lumen compression and collapse or moderate-to-severe distortion of the descending aorta after surgery, the restrictive bare stent technique was adopted to reduce the occurrence of a new aortic rupture induced by the distal stent and the true lumen expanded; and (5) The sheath was removed, and the femoral artery incision was sutured. The criteria for successful surgery included good stent shaping, accurate placement, good closure of the proximal tear of the aortic dissection, no serious internal leakage, and no need for subsequent surgery.

Observation indicators

Clinical characteristics included a history of smoking and drinking, medical history, and left ventricular ejection fraction; surgery-related characteristics included surgical time, main stent type, and vertebral stent and length; postoperative characteristics such as mechanical ventilation, intensive care unit (ICU) stay, and hospitalization times; and central nervous system injury.

Statistical analysis

Measurements corresponding to a normal distribution were expressed as the mean ± SD, non-normally distributed measurements as the median, and count data as percentages. A t-test or χ² test was used for intergroup comparisons. Risk factors were analyzed using multivariate logistic regression analysis. A P value < 0.05 was used as the statistical reference standard, and data were extracted using SPSS 22.0.

RESULTS

The characteristics of the patients in the two groups are shown in Table 1. The two groups observed a significant difference in age and history of hypertension (P < 0.05). The average age of the patients in the injured group was higher than that in the non-injured group, and the number of hypertensive cases was also higher than that in the non-injured group. No significant differences were observed between the two groups in the history of drinking, smoking, diabetes, surgery, or the incidence of coronary heart disease, cerebral infarction, chronic obstructive pulmonary disease, hyperlipidemia, staging, low back pain, left ventricular ejection fraction, or aortic dissection location (P > 0.05).

Table 1 Clinical characteristics of two groups of patients.

Variable	Non-injury group (n = 147)	Injury group (n = 159)	χ2/t	P value
Age	50.74 ± 7.51	59.68 ± 4.15	13.014	< 0.001
History of drinking			0.753	0.385
Yes	75	89
No	72	70
History of smoking			0.005	0.944
Yes	78	85
No	69	74
History of diabetes			1.397	0.237
Yes	27	38
No	120	121
History of surgery			0.007	0.931
Yes	29	32
No	118	127
History of hypertension			29.913	< 0.001
Yes	87	138
No	60	21
Coronary heart disease			0.027	0.871
Yes	26	27
No	121	132
Cerebral infarction			0.268	0.605
Yes	4	6
No	143	153
COPD			1.029	0.310
Yes	35	46
No	112	113
Hyperlipidemia			1.723	0.189
Yes	11	19
No	136	140
Staging			0.281	0.596
Acute stage	39	38
Chronic stage	108	121
Low back pain			0.108	0.742
Yes	101	112
No	46	47
Left ventricular ejection fraction	61.44 ± 8.11	59.67 ± 9.23	1.768	0.078
Aortic dissection location			1.285	0.733
Descending aortic isthmus	109	117
Middle thoracic aorta	27	25
Diaphragm level	9	13
Visceral artery	2	4

COPD: Chronic obstructive pulmonary disease.

The surgery-related characteristics of the two patient groups are shown in Table 2. The procedure-related characteristics of the two groups were compared. This revealed that the difference in operative and mechanical ventilation times between the two teams was statistically significant (P < 0.05). Operation and mechanical ventilation times were longer in the injury group than in the non-injury group. The main or vertebral stent, stent length, coverage of the left subclavian artery, maximum diameter of the descending aorta, and surgical success rate did not significantly differ between the two groups (P > 0.05).

Table 2 Surgical-related characteristics of the two groups of patients.

Variable	Non-injury group (n = 147)	Injury group (n = 159)	χ2/t	P value
Type of main stent			0.166	0.983
Captivia	100	108
Zenith	17	19
Ankura	28	29
Grink	2	3
Vertebral stent	45	48	0.007	0.936
Length of stent	189.91 ± 23.11	186.87 ± 23.37	1.143	0.254
Coverage of left subclavian artery			0.299	0.585
Partial coverage	85	87
Complete coverage	62	72
Maximum diameter of descending aorta	4.21 ± 0.34	4.23 ± 0.27	0.564	0.573
Surgery time	88.93 ± 8.29	109.31 ± 7.56	22.496	< 0.001
Mechanical ventilation time	101.36 ± 10.23	119.52 ± 9.28	16.283	< 0.001
Success rate of surgery	147	159	-	-

The postoperative characteristics of the two groups of patients are shown in Table 3. The postoperative characteristics of the two groups were compared. The outcomes was statistically significant in ICU stay, postoperative recovery time, blood pH value on the first day after surgery, and arterial partial pressure of oxygen (PaO₂) on the first day after surgery between the groups (P < 0.05). The ICU stay and postoperative recovery time of patients in the injury group were longer than those in the non-injury group. The blood pH value on the first day after surgery and PaO₂ on the first day after surgery were inferior to those in the non-injury group. Hospital stay and urine volume on the first postoperative day were not significantly different between the two groups (P > 0.05).

Table 3 Postoperative-related characteristics of the two groups of patients.

Variable	Noninjury group (n = 147)	Injury group (n = 159)	t value	P value
ICU stay time (day)	3.58 ± 0.56	6.70 ± 1.37	25.723	< 0.001
Hospitalization time (day)	17.98 ± 7.65	19.27 ± 6.42	1.602	0.109
Urine volume on the first day after surgery (mL)	1427 ± 621.32	1409 ± 601.26	0.258	0.797
Postoperative recovery time (hour)	1.68 ± 0.56	3.17 ± 1.37	12.303	< 0.001
Blood pH value on the first day after surgery	7.44 ± 0.16	7.37 ± 0.17	3.714	< 0.001
PaO2 on the first day after surgery	101.71 ± 35.87	81.63 ± 37.17	4.801	< 0.001

ICU: Intensive care unit.

Multivariate logistic regression analysis of postoperative central nervous system injury is shown in Table 4. Covariates that were clinically valid in univariate analyses were incorporated into multivariate logistic regression analyses. The outcome indicated that age, surgery time, history of hypertension, mechanical ventilation time, and ICU stay time were independent risk factors for central nervous system injury after TEVAR of type B aortic dissection (P < 0.05).

Table 4 Multivariate logistic regression analysis of postoperative central nervous system injury in patients.

Variable	β	SE	Wald	P	OR	95%CI
Age (year)	0.387	0.172	5.063	0.024	1.473	1.051–2.063
Surgery time (hour)	0.629	0.186	11.436	0.001	1.875	1.303–2.701
History of hypertension	1.053	0.221	22.702	< 0.001	2.866	1.859–4.420
Mechanical ventilation time (hour)	0.445	0.219	4.129	0.042	1.561	1.016–2.397
ICU stay time (day)	0.699	0.187	13.972	< 0.001	2.012	1.394–2.902

ICU: Intensive care unit.

DISCUSSION

Traditional open surgery for type B aortic dissection is difficult to perform and has many postoperative complications, resulting in a high risk of perioperative death[7]. As interventional therapy quickly advances in technology, TEVAR has been extensively recognized in the context of clinical practice and limits trauma while being safe and effective. This procedure has become the first choice for treating type B aortic dissection[8]. However, central nervous system injury after TEVAR is a more common postoperative complication, producing a substantial additional risk of death 30 days or one year after surgery[9]. Therefore, this study analyzed and evaluated the risk factors for central nervous system injury after TEVAR of type B aortic dissection and evaluated the risk factors to improve the prognosis of patients.

After comparing the clinical characteristics of the two patient groups, we discovered that both groups had significant differences in age and history of hypertension. The age of the patients in the injury group was higher than that in the non-injury group, and the number of hypertensive cases was higher than that in the non-injury group. Multivariate logistic regression analysis showed that age and a history of hypertension were independent risk factors for central nervous system injury after TEVAR of type B aortic ratio (OR = 1.473, 2.866, P < 0.05). A previous study stated that the age of patients with central nervous system injury after aortic dissection and the number of patients with hypertension were higher than those without injury and that age and history of hypertension are independent risk factors for central nervous system injury after TEVAR for aortic dissection[10], which is similar to the result of this study. This may be because the degree of atherosclerosis increases with patient age, as does the subsequent incidence of cervical vascular stenosis[11,12]. In addition, surgery requires reconstruction of the aortic arch branch vessels, and long-term hypertension can induce systemic arteriosclerosis, reduce the blood supply to the brain, increase the sensitivity of the brain to the reduced blood supply, and increase the risk of intraoperative embolus shedding and embolism[13,14]. Thus, dynamic blood pressure monitoring should be strengthened during the perioperative period. During surgery, the patient's systolic blood pressure should be controlled at 90–110 mmHg. Blood volume is supplemented immediately after surgery. Fluctuations in blood pressure and the mental state of patients should be closely monitored. Patients' blood pressure should be reasonably controlled to avoid brain injury and improve the therapeutic effect.

After comparing the surgery-related features of both sets of patients, we found significant differences in the operative time and duration of mechanical ventilation between the two groups. Operation and mechanical ventilation times were longer in the injury group than in the non-injury group. Multivariate logistic regression analysis showed that surgery and mechanical ventilation times were individual risk factors for central nervous system injury after TEVAR of type B aortic dissection (OR = 1.875, 1.561, P < 0.05). Earlier research indicated that the surgery and mechanical ventilation times of patients with central nervous system injury after aortic dissection are longer than those without injury. These times are independent risk factors for central nervous system injury after TEVAR of aortic dissection[15]. These results are consistent with those of the present study. This may be because prolonged surgery time increases the risk of atherosclerotic plaque shedding, thrombosis, or air embolism caused by the sheath, guidewire, or catheter, which increases the possibility of cerebral infarction and further causes neurological damage[16]; furthermore, prolonged mechanical ventilation can enhance the risk of pulmonary infection. Tracheal intubation is required in severe cases, which can easily induce hypoxia and cause neurological complications[17]. Studies have demonstrated that prolonged mechanical ventilation may increase the risk of delirium by 10% and that minimizing the duration of mechanical ventilation or early extubation after surgery does not increase the incidence of lung or brain complications, myocardial ischemia, or infarction[18]. Therefore, patients should be evaluated comprehensively before surgery to shorten the surgery time as much as possible to ensure a smooth surgery. Tracheal intubation should be removed from patients who meet the indications for extubation as soon as possible to reduce the duration of mechanical ventilation and the occurrence of neuropsychiatric disorders.

The postoperative characteristics of the two patient groups were compared. The duration of ICU stay differed significantly between the two groups. Patients in the injury group had a longer ICU stay than those in the non-injury group, and polytomous logistic correlation analysis demonstrated that ICU stay was an additional interactive risk factor for CNS injury after thoracic hemangioma repair for type B aortic coarctation (OR = 2.012, P < 0.001). A previous study indicated that the ICU stay time in patients with central nervous system injury after aortic dissection is longer than that in patients without injury and that ICU stay duration is an isolated element for risk assessment of central nervous system injury after TEVAR for aortic dissection[19], which was similar to the results of this study. This may be because the patient is in a closed environment in the ICU and often requires indwelling catheterization, limb restraint, or tracheal intubation, causing discomfort, anxiety, irritability, panic, delirium, and other transient neurological damage[20,21]. In addition, the noise or strong light of various devices in the ICU can affect sympathetic nerve function, increase heart rate, blood pressure, and pain, cause difficulty falling asleep, confusion of the biological clock, and even hallucinations[22,23]. The alarm volume of the equipment and conversations with the medical staff should be reduced as much as possible, and the ICU stay time should be limited to ensure the patient's stable condition.

CONCLUSION

In summary, we demonstrated that age, surgical time, history of hypertension, mechanical ventilation time, and ICU stay time were independent risk factors for central nervous system damage after TEVAR of type B aortic dissection. Optimal diagnosis and treatment by clinical practitioners can be facilitated by the early identification of patients at a heightened risk of central nervous system injury following intrathoracic hemangioma repair of type B aortic coarctation to decrease the associated mortality and enhance the quality of life. However, the patients in this study were all from the same hospital, and the sample size was limited. Future large-sample and multicenter studies are needed to explore the factors influencing postoperative central nervous injuries.