Large distal tear of aortic dissection: Risk factor for postoperative distal aortic segmental enlargement

Lizhi Lv; Yanqing Chen; Yu Shen; Zaiping Jing; Yi Shi; Simeng Zhang; Qingsheng Lu

doi:10.4103/2589-9686.377613

ORIGINAL STUDY

Year : 2023 | Volume : 6 | Issue : 1 | Page : 11-15

Large distal tear of aortic dissection: Risk factor for postoperative distal aortic segmental enlargement

Lizhi Lv¹, Yanqing Chen², Yu Shen², Zaiping Jing², Yi Shi³, Simeng Zhang⁴, Qingsheng Lu²
¹ Department of Pediatric Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Shanghai, China
² Department of Vascular, Changhai Hospital, Shanghai, India
³ Department of Cardiac Surgery, Peking University People's Hospital, Peking, China
⁴ Department of Vascular, Changhai Hospital, Shanghai; Department of Cardiac Surgery, Peking University People's Hospital, Peking, China

Date of Submission	31-Oct-2022
Date of Decision	22-Feb-2023
Date of Acceptance	24-Feb-2023
Date of Web Publication	26-May-2023

Correspondence Address:
Prof. Qingsheng Lu
Department of Vascular Surgery, Changhai Hospital, The First Affiliated Hospital of Navy Military Medical University, 168 Changhai Rd., Shanghai, 200433
India
Dr. Simeng Zhang
Department of Cardiac Surgery, Peking Universtiy People's Hospital, No. 11 Xizhimen South Rd., Xicheng District, Beijing, 100044
China

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2589-9686.377613

Abstract

BACKGROUND: The traditional treatment for aortic dissections (ADs) is a proximal repair of AD, but the long-term prognosis of residual distal dissection is unsatisfactory. The distal aortic intimal tear of distal aortic segmental enlargement (DASE) is evaluated via its size, with risk assessment, and assessed its risk, which will provide clinicians with diagnosis and treatment direction.
METHODS: We analyzed 419 ADs patients who underwent radiographic examination of the aorta between September 1999 and May 2014. We recorded the area of the aortic intimal tear and divided it into two groups (75 patients in DASE group and 344 patients in non-DASE group). Logistics regression analysis or natural logarithm transformation was used to explore the potential risk of remaining distal tears to DASE, while the Logistic multiple regress equations were used to find out the independent risk factors.
RESULTS: The postoperative large tear was defined as short diameter ≥5.0 mm. The independent risk factors of DASE are as follows: Short diameter of postoperative tears (odds ratios [ORs], 1.10;95% confidence interval [CI], 1.02–1.19; P < 0.0120); short diameter of the first tear after operation (OR, 1.12; 95% CI, 1.00–1.26; P < 0.0580) and the existence of large tears (OR, 1.13; 95% CI, 1.01–1.26; P < 0.0298).
CONCLUSIONS: Our findings suggest that the size of the remaining tears and the existence of large tears are the key risk factors for patients with DASE. Patients with large remaining tears should be supervised regularly and treated timely.

Keywords: Distal aortic segmental enlargement, logistic analysis, risk factor, size of the remaining tears

How to cite this article:
Lv L, Chen Y, Shen Y, Jing Z, Shi Y, Zhang S, Lu Q. Large distal tear of aortic dissection: Risk factor for postoperative distal aortic segmental enlargement. Vasc Invest Ther 2023;6:11-5

How to cite this URL:
Lv L, Chen Y, Shen Y, Jing Z, Shi Y, Zhang S, Lu Q. Large distal tear of aortic dissection: Risk factor for postoperative distal aortic segmental enlargement. Vasc Invest Ther [serial online] 2023 [cited 2023 Jun 8];6:11-5. Available from: https://www.vitonline.org/text.asp?2023/6/1/11/377613

Introduction

The incidence of distal dilatation after aortic dissection (AD) is not rare, and success of proximal operation can still leave complications. In addition to the local aortic dilatation, the postoperative aortic remodeling of the whole forehead in patients with distal dilatation was also worse than that in patients with a distal aortic segmental enlargement (DASE).^[1] At the same time, some research revealed that residual arch vessel tears could lead to unfavorable distal aortic remodeling and that intimal tears in the proximal descending thoracic aorta were the most significant factor of the increase in distal aortic diameter.^[2],[3]

Our previous studies confirmed that the location of residual tears was the key risk factor of DASE. Long-segment aortic repair and aggressive exclusion of all distal tears located in the thoracic descending aorta at the moment of the first repair proved to be a very effective strategy.^[4]

Herein, we have done a quantitative evaluation of the impact of the size of the remaining intimal tear on DASE.

Methods

Study population

The clinical outcomes of Stanford Type A and Stanford Type B AD treated with proximal repair from September 1999 to May 2014 were retrospectively analyzed. All patients underwent postoperative computed tomographic angiography (CTA) examination and were followed up for at least 1 year without further intervention. Patients with no residual dissection, complete thrombosis of false lumen (FL), penetrating aortic ulcer, or intramural hematoma were excluded from the study. Patients with type I endoleak, new proximal entry, or other aortic-related complications within 1 year were also excluded.

The study was approved by the institutional review committee, and permission was received from patients. DASE was defined as the diameter of the residual dissection more than 1.5 times of the normal aorta or the growth rate of diameter >10 mm/year.^[4]

Data collection

All CTA imaging was performed on a multislice CTA scanner with 16 - or 64-detector Siemens Sensation configuration. The acquired CTA data sets were transferred to a TeraRecon Vascular 4.4.6 workstation (Aquarius iNtuition Edtion, TeraRecon, Foster City, California) in Digital Imaging and Communications in Medicine format for analysis.

Description of the tears

The number and size of the intimal tears in patients with AD were recorded preoperatively, postoperatively, and during the follow-up. The size of the tears was recorded as short diameters and long diameters, which were the maximum distance of the fissure in the cross-section and the sagittal plane, respectively [Figure 1].

Figure 1: The size of the tears was recorded in the sagittal plane and the maximum cross section of the aorta after 3-DR. (a) The red arrow is the largest sagittal plane of the tear, which denotes the long diameter, the green line is the centre line of true lumen of aortic dissection; (b) The red arrow indicates the largest cross section of the tear, which denotes the short diameter. LT: Length of tear, WT: Width of tear, 3-DR: Three dimensional reconstruction

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Data analysis

Statistical significance was defined as probability P < 0.05, and all P values were 2-sided. Clinically significant rates were reported with 95% confidence intervals (CIs), and continuous variables were expressed as mean ± standard deviation and were compared using independent t-test or Mann–Whitney U-test. Logistic regression analysis was used for normally distributed continuous variables, and natural logarithmic transformation was used for skewed distribution measurement data to analyze the risk of tears. We fitted the dose–response relationship between diameters of the long and short axes of all the tears after proximal repair using generalized additive models and further found the optimal cut-off point. Logistic multi-regress equations were performed to identify independent risk factors and when inter-class correlation exists between variables, generalized estimation equation was used. Results were summarized to odds ratios (ORs) and 95% CI. All analyses were performed with Empower (R) (www.empowerstats.com, X and Y Solutions, Inc., Boston MA) and R (http://www.R-project.org).

Results

Follow-up information

From 1999 to 2014, there were 1703 AD patients treated in our hospital. Five hundred and twenty-nine patients were excluded because undergone only medical therapy. Other 212 patients were excluded, details can be found in our previous study [clinical characteristics showed in Supplementary Material].^[4] Among 962 eligible patients, only in 419 cases, an angio-computed tomography scan was available at 1-year follow-up after the operation in which the morphological features could be analyzed (75 with DASE, and 344 without).

Evaluation of the tears after proximal repair

There was no significant difference between patients with and without DASE in the long diameter of postoperative tears [Table 1], but the short diameter of postoperative tears was significantly larger in patients with DASE than those without (5.3 mm ± 2.7 mm in the DASE group vs. 4.4 mm ± 2.7 mm in the non-DASE group, P < 0.001). Curve fitting was performed according to the diameters of the long and short axes of all the tears after proximal repair [Figure 2]. The inflection point of the short diameter of the cleft was 5.0 mm, while the curve of the long diameter was waved after the first inflection point of 10 mm.

Table 1: Comparison of long and short diameter of postoperative tears between distal aortic segmental enlargement group and nondistal aortic segmental enlargement group

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Figure 2: The long diameter and short diameter of the tears were substituted into the GAM, and the solid red line represented the smooth-fitting curve between the variables. Blue bands represent 95% of confidence interval from the fit. It was found that both the long diameter and short diameter had nonlinear correlations with DASE (P < 0.001), the inflection point of the short diameter is 5 mm, and the inflection point of the long diameter is 10 mm. GAM: Generalized additive model, DASE: Distal aortic segmental enlargement

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The short diameter of the tears was defined as 5.0 mm, and the number of tears in non-DASE group and DASE group was counted, as shown in [Table 2], indicating that there was a statistical difference between the two groups. Univariate analysis [Table 3] showed that the short diameter of the tears ≥5.0 mm increased the risk of postoperative DASE. Therefore, postoperative large tear was defined as short diameter ≥5.0 mm.

Table 2: Study population description of short diameter≥5 mm in distal aortic segmental enlargement group and nondistal aortic segmental enlargement group

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Table 3: Univariate analysis of distal aortic segmental enlargement and size of tears

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The number of postoperative large tear in the DASE group was significantly higher than that in the non-DASE group (2.672 ± 3.379 vs. 1.541 ± 2.636, P < 0.001) [Table 4].

Table 4: Comparison of the number of postoperative large tears between distal aortic segmental enlargement group and nondistal aortic segmental enlargement group

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Risk factors of postoperative distal aortic segmental enlargement

The maximum long diameter of postoperative tears and the long diameter of the first tear after operation were not statistically significant, while the maximum short diameter of postoperative tears (OR, 1.10; 95% CI, 1.02–1.19; P = 0.0120), the short diameter of the first tear after operation (OR, 1.08; 95% CI, 1.00–1.18; P = 0.0528) and the number of large tears (OR, 1.13; 95% CI, 1.01–1.26; P = 0.0298) were the risk factors of DASE after proximal repair.

The independent risk factors of postoperative distal aortic enlargement were the maximum short diameter of the postoperative tears (OR, 1.11; 95% CI, 0.98–1.27; P = 0.1117) and the short diameter of the first tear after operation (OR, 1.12; 95% CI, 1.00–1.26; P = 0.0580). The number of large tears was not the independent risk factor of postoperative distal dilation (OR, 1.07; 95% CI, 0.87–1.32; P = 0.5004), while the existence of large tear is the independent risk factor of postoperative DASE (OR, 1.31; 95% CI, 1.11–1.52; P = 0.0432) [Table 5].

Table 5: Risk factors of post-operative distal aortic segmental enlargement with the use of univariate logistic regression and multivariate logistic regression

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Discussion

The purpose of AD repair is to avoid the aortic rupture, and the primary therapeutic purpose is to block blood flow into FL from the proximal end of the descending aorta by isolating the proximal tear so that FL thrombosis can promote aortic remodeling. Theoretically, the closure of the proximal tear results in the absence of continuous flow into the proximal FL, which reduces the pressure in the distal FL and changes of distal aortic dilation and rupture.^[5],[6] In the clinical follow-up, we found that most patients with type B AD had a stable distal dissection after the closure of the proximal tear by endovascular treatment, however, a large number of patients (13.41%) were found to have a progressive enlargement of distal reinforcement or even rupture.^[4]

Our previous studies confirmed that the closer distance of the first intimal tear to the left subclavian artery, greater maximum distance between two tears and average distance among remaining tears were independent risk factors.^[4] Theoretically, the coverage of proximal entry tear promotes proximal thrombosis so that persistent flow throughout the patent distal FL should be associated with lower pressures minimizing the risk of aneurysmal enlargement and rupture. We found that the size of residual tears (OR, 1.56; 95% CI, 1.38–1.76; P < 0.0001) appeared to be the risk factor after minimizing the interclass correlation. There were 79.97% of patients having more than three tears in this study. For multiple residual tears, it was difficult to tell inflow and outflow tracts. Therefore, the larger the tears were, the higher the pressure of FL was.^[4] These results are consistent with those of the researchers, who found that the persistence of the distal tears may induce aorta expansion in the long run, and may result in inevitable thoracic abdominal aorta replacement or even aorta rupture.^[7]

At present, most of the studies focus on the location of the distal tear of AD and the effect of intervention on the prognosis of AD surgery,^{[2],[6],[8],[9],[10]} but there is no quantitative or qualitative analysis of the tear of AD. In this study, it was found that the maximum long diameter and the number of large tears had no significant correlation with distal dilatation. However, the maximum postoperative short diameter of the tears was significantly correlated with distal dilatation after dissection, with specific effects as follows: The greater the maximum postoperative short diameter of the tear was, the greater the risk of distal dilatation was, and the risk ratio of distal dilatation was 1.11 (OR value) for every 1 mm increase in the short diameter; At the same time, we found that the greater the short diameter of the first tear after operation, the greater the risk of distal dilatation was, and the risk ratio of distal dilatation was 1.12 (OR value) for each 1 mm increase in the shorter diameter.

Studies have pointed out that the patients with dissection involving renal abdominal aorta had a 50% increase in aorta volume after the operation, while those without the involvement only had a 27% increase. Andachen also pointed out that the poorer renal abdominal aortic remodeling could be caused by the tears in the distal end as FL gaps, despite the treatment of the rupture above the diaphragm feet plane. Lombardi et al.^[11] also showed that patients with postoperative lacerations were accompanied by an unobtrusive FL, which was associated with poor prognosis. Kato et al.^[12] proposed that distal neoplastic dilatation after acute dissection was related to the vulnerability of new openings in the thin intima. However, our previous study found that the number of distal tears, even the possible existence of concealed tears and the appearance of new tears were not risk factors for DASE, which was different from their speculated direction.^[4]

Schoder et al.^[13] proposed long-term survival associated with aortic remodeling, but Sayer et al.^[14] proposed that the abdominal aorta showed an increase in volume after endovascular repair, the impact of ΔTL/ΔFL was greater than true lumen (TL)/FL, as a result, it is not too bad in terms of diameter increase in the abdominal aorta when the postoperative increase was mainly caused by the increase of the TL. Kim et al.^[15] also found that when the increase in diameter or volume of the renal inferior abdominal aorta was not clinically significant, this increase did not require further surgical treatment. However, when the increase of FL diameter is significantly larger than that of TL, it indicates that DASE may occur.

This was consistent with our study. Aortic diameter increased in most of the postoperative aortic planes at the initial stage, mainly due to the increase of TL, but with FL thrombosis, aortic diameter gradually decreased. At the same time, the tears with shorter diameter may close during the follow-up period, making the distal aorta dilatation unobvious, while the tears with large short diameter were less likely to close after the surgery, it increased the blood flow into the FL pair, thus increased the pressure on the FL and increased the risk of DASE.

Any internal or external causes that result in weakness and structural abnormalities of the aortic wall, as well as the presence of maximum short diameter and large intimal tear of the aorta are risk factors for distal dilatation after the first stage of AD. The larger short diameter of the postoperative tear was an independent risk factor for distal distention after the first stage of AD.

For high-risk patients, close follow-up and accurate evaluation are necessary to help clinicians to grasp the timing and strategy of surgery to achieve better outcomes.

Conclusions

Undoubtedly, the residual distal dissection after proximal repair of AD is a long-term risk factor for poor prognosis that clinicians should pay close attention to. Our research results indicate that the size of the residual tears and the number of large tears are the key to DASE patients with risk factors, so if clinicians intend to improve the long-term prognosis, they should focus on the tear size of the distal dissection and the number of large tears, timely intervention may be a feasible way to improve the survival rate of aortic dissection patients with proximal repair. With the continuous improvement of the quality of diagnosis and treatment, we should pay more attention to the small differences in the process of diagnosis and treatment, and ultimately benefit the patients.

Limitations

Our study has several limitations. First of all, the study was retrospective and descriptive. More evidence is needed for clinicians to reference and handle the distal tears. Secondly, our data only reflect the treatment pattern of top-tier cardiovascular centers in our country, but not the treatment pattern of hospitals at all levels.

Financial support and sponsorship

Supported by Grants from the National Natural Science Foundation of China (81330034, 81800403, 81170291).

Conflicts of interest

There are no conflicts of interest.

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