Evaluating the diagnostic accuracy of maximal aortic diameter, length and volume for prediction of aortic dissection

Aortic events and relative survival in patients with moderately dilated proximal thoracic aorta

Objectives. This study describes growth, local and remote aortic events, and survival in patients with proximal (root, ascending) aortic diameters just below threshold for operation. Methods. Patients with proximal aortic diameter of 4.5 to 5.4 cm at baseline, were followed with serial computed tomography studies and data collected retrospectively. Aortic growth rate was estimated using mixed effects modelling. Clinical and radiological features associated with outcomes (all-cause death, aortic death, local or remote aortic events (dissection, rupture, intramural hematoma, or intervention)) were assessed with Cox analysis. Survival and freedom from events were estimated using Kaplan-Meier methods. Results. 80 patients underwent 274 CT scans during 265 patient-years. Median proximal aortic growth was 0.2 cm in 3 years. 32 events occurred in 28 patients (35%). Eleven events were local, all elective proximal aortic surgery. Nine events were remote: 5 type B aortic dissections, 3 descending aneurysms undergoing elective repair, and one infrarenal aortic rupture. Twelve patients died, half of type B aortic dissection. Relative survival compared to a matched normal population was 82% (95% confidence limits 55-98%) at 10 years. In Cox analysis, increased descending aortic diameter was an independent predictor of all-cause death (hazard ratio [HR], 1.39) and aortic death (HR 1.96). Conclusions. Descending, but not proximal, aortic growth was predictive of lethal events. The decreased relative survival, the substantial number of remote aortic events and aortic deaths strongly suggest continuous serial CT surveillance of the entire aorta. Other indicators than proximal aortic diameter appear needed to improve management of this patient group.

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

Impact of nondiameter aortic indices on surgical eligibility: Results from the Treatment in Thoracic Aortic Aneurysm: Surgery Versus Surveillance (TITAN: SvS) randomized controlled trial

OBJECTIVES

Traditional criterion for intervention on an asymptomatic ascending aortic aneurysm has been a maximal aortic diameter of 5.5 cm or more. The 2022 American College of Cardiology/American Heart Association aortic guidelines adopted cross-sectional aortic area/height ratio, aortic size index, and aortic height index as alternate parameters for surgical intervention. The objective of this study was to evaluate the impact of using these newer indices on patient eligibility for surgical intervention in a prospective, multicenter cohort with moderate-sized ascending aortic aneurysms between 5.0 and 5.4 cm.

METHODS

Patients enrolled from 2018 to 2023 in the randomization or registry arms of the multicenter trial, Treatment In Thoracic Aortic aNeurysm: Surgery versus Surveillance, were included in the study. Clinical data were captured prospectively in an online database. Imaging data were derived from a core computed laboratory.

RESULTS

Among the 329 included patients, 20% were female. Mean age was 65.0 ± 11.6 years, and mean maximal aortic diameter was 50.8 ± 3.9 mm. In the one-third of all patients (n = 109) who met any 1 of the 3 criteria (ie, aortic size index ≥3.08 cm/m2, aortic height index ≥3.21 cm/m, or cross-sectional aortic area/height ≥ 10 cm2/m), their mean maximal aortic diameter was 52.5 ± 0.52 mm. Alternate criteria were most commonly met in women compared with men: 20% versus 2% for aortic size index (P < .001), 39% versus 5% for aortic height index (P < .001), and 39% versus 21% for cross-sectional aortic area/height (P = .002), respectively.

CONCLUSIONS

One-third of patients in Treatment In Thoracic Aortic aNeurysm: Surgery versus Surveillance would meet criteria for surgical intervention based on novel parameters versus the classic definition of diameter 5.5 cm or more. Surgical thresholds for aortic size index, aortic height index, or cross-sectional aortic area/height ratio are more likely to be met in female patients compared with male patients.

A predictive model of 30-day mortality in patients with acute type A aortic dissection

OBJECTIVE

Acute type A aortic dissection (ATAAD) is a life-threatening cardiovascular disease that requires an effective predictive model to predict and assess a patient's risk of death. Our study aimed to construct a model for predicting the risk of 30-day death in patients with ATAAD and the prediction accuracy of the German Registry of Acute Aortic Dissection Type A (GERAADA) Score and the European System for Cardiac Operative Risk Evaluation (EuroSCORE II) was verified.

MATERIALS AND METHODS

Between June 2019 and June 2023, 109 patients with ATAAD underwent surgical treatment at our hospital (35 in the death group and 74 in the survival group). The differences in image parameters between the two groups were compared. Search for independent predictors and develop models that predict 30-day mortality in patients with ATAAD. GERAADA Score and EuroSCORE II were retrospectively calculated and indicated mortality was assessed using the receiver operating characteristic (ROC) curve.

RESULTS

Logistic regression analysis showed that ascending aortic length and pericardial effusion were independent predictors of death within 30 days in patients with ATAAD. We constructed four models, GERAADA Score (Model 1), EuroSCORE II (Model 2), Model 1, ascending aorta length, and pericardial effusion (Model 3), and Model 2, ascending aorta length, and pericardial effusion (Model 4). The area under the curve (AUC = 0.832) of Model 3 was significantly different from those of Models 1 (AUC = 0.683) and 2 (AUC = 0.599), respectively (p < 0.05, DeLong test).

CONCLUSIONS

Adding ascending aorta length and pericardial effusion to the GERAADA Score can improve the predictive power of 30-day mortality in patients with ATAAD.

The correlation study between the length and angle of ascending aortic and the incidence risk of acute type A aortic dissection

Objective

This study utilized computed tomography angiography (CTA) to assess the risk of acute type A aortic dissection (ATAAD) by analyzing the imaging morphology indicators of the ascending aorta, along with the relevant risk factors associated with aortic dissection.

Methods

The study utilized a retrospective observational research design. The population consisted of 172 patients who received treatment in the Department of Cardiothoracic Surgery at Qilu Hospital, Shandong University, from January 2018 to December 2022. The patients were divided into two groups: the ATAAD group (n = 97) and the thoracic aortic aneurysm group (TAA, n = 75). Demographic data and ascending aorta CTA measurements were collected from all patients. Single factor and multivariate logistic regression were employed to analyze the statistical differences in clinical data and ascending aorta CTA imaging morphology indicators between the two groups.

Results

The variables were included in logistic multivariate analysis for further screening, indicating that the length of the ascending aorta (LAA) before ATAAD (OR = 3.365; 95% CI :1.742-6.500, P<0.001), ascending arch angle (asc-arch angle, OR = 0.902; 95% CI: 0.816-0.996, P = 0.042) and the maximum aortic diameter (MAD) before ATAAD, (OR = 0.614; 95% CI: 0.507-0.743, P<0.001) showed statistically significant differences.

Conclusions

This study suggests that increased LAA and MAD, as well as a smaller asc-arch angle may be high-risk factors for the onset of ATAAD.

Deep Learning-Based Analysis of Aortic Morphology From Three-Dimensional MRI

BACKGROUND

Quantification of aortic morphology plays an important role in the evaluation and follow-up assessment of patients with aortic diseases, but often requires labor-intensive and operator-dependent measurements. Automatic solutions would help enhance their quality and reproducibility.

PURPOSE

To design a deep learning (DL)-based automated approach for aortic landmarks and lumen detection derived from three-dimensional (3D) MRI.

STUDY TYPE

Retrospective.

POPULATION

Three hundred ninety-one individuals (female: 47%, age = 51.9 ± 18.4) from three sites, including healthy subjects and patients (hypertension, aortic dilation, Turner syndrome), randomly divided into training/validation/test datasets (N = 236/77/78). Twenty-five subjects were randomly selected and analyzed by three operators with different levels of expertise.

FIELD STRENGTH/SEQUENCE

1.5-T and 3-T, 3D spoiled gradient-recalled or steady-state free precession sequences.

ASSESSMENT

Reinforcement learning and a two-stage network trained using reference landmarks and segmentation from an existing semi-automatic software were used for aortic landmark detection and segmentation from sinotubular junction to coeliac trunk. Aortic segments were defined using the detected landmarks while the aortic centerline was extracted from the segmentation and morphological indices (length, aortic diameter, and volume) were computed for both the reference and the proposed segmentations.

STATISTICAL TESTS

Segmentation: Dice similarity coefficient (DSC), Hausdorff distance (HD), average symmetrical surface distance (ASSD); landmark detection: Euclidian distance (ED); model robustness: Spearman correlation, Bland-Altman analysis, Kruskal-Wallis test for comparisons between reference and DL-derived aortic indices; inter-observer study: Williams index (WI). A WI 95% confidence interval (CI) lower bound >1 indicates that the method is within the inter-observer variability. A P-value <0.05 was considered statistically significant.

RESULTS

DSC was 0.90 ± 0.05, HD was 12.11 ± 7.79 mm, and ASSD was 1.07 ± 0.63 mm. ED was 5.0 ± 6.1 mm. A good agreement was found between all DL-derived and reference aortic indices (r >0.95, mean bias <7%). Our segmentation and landmark detection performances were within the inter-observer variability except the sinotubular junction landmark (CI = 0.96;1.04).

DATA CONCLUSION

A DL-based aortic segmentation and anatomical landmark detection approach was developed and applied to 3D MRI data for achieve aortic morphology evaluation.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Male-female differences in thoracic aortic diameters at presentation of acute type A aortic dissection

Background

Acute type A aortic dissection (ATAAD) is a highly lethal event, associated with aortic dilatation. It is not well known if patient height, weight or sex impact the thoracic aortic diameter (TAA) at ATAAD. The study aim was to identify male-female differences in TAA at ATAAD presentation.

Methods

This retrospective cross-sectional study analysed all adult patients who presented with ATAAD between 2007 and 2017 in two tertiary care centres and underwent contrast enhanced computed tomography (CTA) before surgery. Absolute aortic diameters were measured at the sinus of Valsalva (SoV), ascending (AA) and descending thoracic aorta (DA) using double oblique reconstruction, and indexed for body surface area (ASI) and height (AHI). Z-scores were calculated using the Campens formula.

Results

In total, 59 % (181/308) of ATAAD patients had CT-scans eligible for measurements, with 82 female and 99 male patients. Females were significantly older than males (65.5 ± 12.4 years versus 60.3 ± 2.3, p = 0.024). Female patients had larger absolute AA diameters than male patients (51.0 mm [47.0-57.0] versus 49.0 mm [45.0-53.0], p = 0.023), and larger ASI and AHI at all three levels. Z-scores for the SoV and AA were significantly higher for female patients (2.99 ± 1.66 versus 1.34 ± 1.77, p < 0.001 and 5.27 [4.38-6.26] versus 4.06 [3.14-5.02], p < 0.001). After adjustment for important clinical factors, female sex remained associated with greater maximal TAA (p = 0.019).

Conclusion

Female ATAAD patients had larger absolute ascending aortic diameters than males, implying a distinct timing in disease presentation or selection bias. Translational studies on the aortic wall and studies on growth patterns should further elucidate these sex differences.

Automated cross-sectional view selection in CT angiography of aortic dissections with uncertainty awareness and retrospective clinical annotations

Surveillance imaging of patients with chronic aortic diseases, such as aneurysms and dissections, relies on obtaining and comparing cross-sectional diameter measurements along the aorta at predefined aortic landmarks, over time. The orientation of the cross-sectional measuring planes at each landmark is currently defined manually by highly trained operators. Centerline-based approaches are unreliable in patients with chronic aortic dissection, because of the asymmetric flow channels, differences in contrast opacification, and presence of mural thrombus, making centerline computations or measurements difficult to generate and reproduce. In this work, we present three alternative approaches - INS, MCDS, MCDbS - based on convolutional neural networks and uncertainty quantification methods to predict the orientation (ϕ,θ) of such cross-sectional planes. For the monitoring of chronic aortic dissections, we show how a dataset of 162 CTA volumes with overall 3273 imperfect manual annotations routinely collected in a clinic can be efficiently used to accomplish this task, despite the presence of non-negligible interoperator variabilities in terms of mean absolute error (MAE) and 95% limits of agreement (LOA). We show how, despite the large limits of agreement in the training data, the trained model provides faster and more reproducible results than either an expert user or a centerline method. The remaining disagreement lies within the variability produced by three independent expert annotators and matches the current state of the art, providing a similar error, but in a fraction of the time.

The Maastricht Acquisition Platform for Studying Mechanisms of Cell-Matrix Crosstalk (MAPEX): An Interdisciplinary and Systems Approach towards Understanding Thoracic Aortic Disease

Current management guidelines for ascending thoracic aortic aneurysms (aTAA) recommend intervention once ascending or sinus diameter reaches 5-5.5 cm or shows a growth rate of >0.5 cm/year estimated from echo/CT/MRI. However, many aTAA dissections (aTAAD) occur in vessels with diameters below the surgical intervention threshold of <55 mm. Moreover, during aTAA repair surgeons observe and experience considerable variations in tissue strength, thickness, and stiffness that appear not fully explained by patient risk factors. To improve the understanding of aTAA pathophysiology, we established a multi-disciplinary research infrastructure: The Maastricht acquisition platform for studying mechanisms of tissue-cell crosstalk (MAPEX). The explicit scientific focus of the platform is on the dynamic interactions between vascular smooth muscle cells and extracellular matrix (i.e., cell-matrix crosstalk), which play an essential role in aortic wall mechanical homeostasis. Accordingly, we consider pathophysiological influences of wall shear stress, wall stress, and smooth muscle cell phenotypic diversity and modulation. Co-registrations of hemodynamics and deep phenotyping at the histological and cell biology level are key innovations of our platform and are critical for understanding aneurysm formation and dissection at a fundamental level. The MAPEX platform enables the interpretation of the data in a well-defined clinical context and therefore has real potential for narrowing existing knowledge gaps. A better understanding of aortic mechanical homeostasis and its derangement may ultimately improve diagnostic and prognostic possibilities to identify and treat symptomatic and asymptomatic patients with existing and developing aneurysms.

Ascending Aortic Volume: A Feasible Indicator for Ascending Aortic Aneurysm Elective Surgery?

Diameter-based criterion have been widely adopted for preventive surgery of ascending thoracic aortic aneurysm (ATAA). However, recent and growing evidence has shown that diameter-based methods may not be sufficient for identifying patients who are at risk of an ATAA. In this study, fluid-structure interaction (FSI) analysis was performed on one-hundred ATAA geometries reconstructed from clinical data to examine the relationship between hemodynamic conditions, ascending aortic volume (AAV), ascending aortic curvature, and aortic ratios measured from the reconstructed 3D models. The simulated hemodynamic and biomechanical parameters were compared among different groups of ATAA geometries classified based on AAV. The ATAAs with enlarged AAV showed significantly compromised hemodynamic conditions and higher mechanical wall stress. The maximum oscillatory shear index (OSI), particle residence time (PRT) and wall stress (WS) were significantly higher in enlarged ATAAs compared with controls (0.498 [0.497, 0.499] vs 0.499 [0.498, 0.499], p = 0.002, 312.847 [207.445, 519.391] vs 996.047 [640.644, 1573.140], p < 0.001, 769.680 [668.745, 879.795] vs 1072.000 [873.060, 1280.000] kPa, p < 0.001, respectively). Values were reported as median with interquartile range (IQR). AAV was also found to be more strongly correlated with these parameters compared to maximum diameter. The correlation coefficient between AAV and average WS was as high as 0.92 (p < 0.004), suggesting that AAV might be a feasible risk identifier for ATAAs. STATEMENT OF SIGNIFICANCE: Ascending thoracic aortic aneurysm is associated with the risk of dissection or rupture, creating life-threatening conditions. Current surgical intervention guidelines are purely diameter based. Recently, many studies proposed to incorporate other morphological parameters into the current clinical guidelines to better prevent severe adverse aortic events like rupture or dissection. The purpose of this study is to gain a better understanding of the relationship between morphological parameters and hemodynamic parameters in ascending aortic aneurysms using fluid-solid-interaction analysis on patient-specific geometries. Our results suggest that ascending aortic volume may be a better indicator for surgical intervention as it shows a stronger association with pathogenic hemodynamic conditions.

Magnetic Resonance Imaging and Computed Tomography for the Noninvasive Assessment of Arterial Aging: A Review by the VascAgeNet COST Action

Magnetic resonance imaging and computed tomography allow the characterization of arterial state and function with high confidence and thus play a key role in the understanding of arterial aging and its translation into the clinic. Decades of research into the development of innovative imaging sequences and image analysis techniques have led to the identification of a large number of potential biomarkers, some bringing improvement in basic science, others in clinical practice. Nonetheless, the complexity of some of these biomarkers and the image analysis techniques required for their computation hamper their widespread use. In this narrative review, current biomarkers related to aging of the aorta, their founding principles, the sequence, and postprocessing required, and their predictive values for cardiovascular events are summarized. For each biomarker a summary of reference values and reproducibility studies and limitations is provided. The present review, developed in the COST Action VascAgeNet, aims to guide clinicians and technical researchers in the critical understanding of the possibilities offered by these advanced imaging modalities for studying the state and function of the aorta, and their possible clinically relevant relationships with aging.

Ascending Aorta Dissection Before 5.5 cm Diameter; "It Wasn't Raining When Noah Built the Ark"

INTRODUCTION

The aim of this study was to compare mean maximum ascending aortic diameter at the time of acute aortic dissection with the current surgical threshold for elective ascending aortic operations on non-syndromic thoracic aortic aneurysms.

MATERIAL AND METHODS

All consecutive non-syndromic adult patients admitted for acute type A aortic dissection in a single tertiary centre were prospectively enrolled from April 2020 to March 2021. The primary endpoint was the difference between mean maximum aortic diameter at the time of dissection and the 5.5 cm threshold for elective repair. Secondary endpoints included 30-day/in-hospital mortality, aortic length and comparison with normal controls, length/height ratio index, "actual" preoperative Euroscore II and "predicted" Euroscore II if electively operated.

RESULTS

Among 31 patients ageing 67.3±12.03 years on average, mean maximum aortic diameter at the time of dissection was 5.13±0.66 cm, significantly lower than the guidelines-derived surgical threshold of 5.5 cm (p=0.004). Mean aortic length was 11±1.47 cm, also significantly longer compared normal controls reported in the literature (p<0.001). The 30-day/in-hospital mortality was 35.5%. Mean length/height ratio index was 6.18±0.76 cm/m. Finally, mean "actual" preoperative Euroscore II was 10.43±4.07 which was significantly higher than the 1.47±0.57 "predicted" Euroscore II (p<0.05).

CONCLUSIONS

The maximum aortic diameter at the time of acute type A aortic dissection of non-syndromic cases was significantly lower than the current recommendation for elective repair. Lowering of the current diameter-based surgical threshold of 5.5 cm may be profitable in terms of prevention, but further investigations should be undertaken. Length-based thresholds could also add to timely aortic dissection prevention.

Assessment of shape-based features ability to predict the ascending aortic aneurysm growth

The current guidelines for the ascending aortic aneurysm (AsAA) treatment recommend surgery mainly according to the maximum diameter assessment. This criterion has already proven to be often inefficient in identifying patients at high risk of aneurysm growth and rupture. In this study, we propose a method to compute a set of local shape features that, in addition to the maximum diameter D, are intended to improve the classification performances for the ascending aortic aneurysm growth risk assessment. Apart from D, these are the ratio DCR between D and the length of the ascending aorta centerline, the ratio EILR between the length of the external and the internal lines and the tortuosity T. 50 patients with two 3D acquisitions at least 6 months apart were segmented and the growth rate (GR) with the shape features related to the first exam computed. The correlation between them has been investigated. After, the dataset was divided into two classes according to the growth rate value. We used six different classifiers with input data exclusively from the first exam to predict the class to which each patient belonged. A first classification was performed using only D and a second with all the shape features together. The performances have been evaluated by computing accuracy, sensitivity, specificity, area under the receiver operating characteristic curve (AUROC) and positive (negative) likelihood ratio LHR+ (LHR-). A positive correlation was observed between growth rate and DCR (r = 0.511, p = 1.3e-4) and between GR and EILR (r = 0.472, p = 2.7e-4). Overall, the classifiers based on the four metrics outperformed the same ones based only on D. Among the diameter-based classifiers, k-nearest neighbours (KNN) reported the best accuracy (86%), sensitivity (55.6%), AUROC (0.74), LHR+ (7.62) and LHR- (0.48). Concerning the classifiers based on the four shape features, we obtained the best accuracy (94%), sensitivity (66.7%), specificity (100%), AUROC (0.94), LHR+ (+∞) and LHR- (0.33) with support vector machine (SVM). This demonstrates how automatic shape features detection combined with risk classification criteria could be crucial in planning the follow-up of patients with ascending aortic aneurysm and in predicting the possible dangerous progression of the disease.

Imaging surveillance for complications after primary surgery for type A aortic dissection

Acute type A aortic dissection (ATAAD) is a life-threatening condition that requires emergency surgery to avert fatal outcome. Conventional surgical procedures comprise excision of the entry tear and replacement of the proximal aorta with a synthetic vascular graft. In patients with DeBakey type I dissection, this approach leaves a chronically dissected distal aorta, putting them at risk for progressive dilatation, dissection propagation and aortic rupture. Therefore, ATAAD survivors should undergo serial imaging for evaluation of the aortic valve, proximal and distal anastomoses, and the aortic segments beyond the distal anastomosis. The current narrative review aims to describe potential complications in the early and late phases after ATAAD surgery, with focus on their specific imaging findings.

Existing and Emerging Approaches to Risk Assessment in Patients with Ascending Thoracic Aortic Dilatation

Ascending thoracic aortic aneurysm is a life-threatening disease, which is difficult to detect prior to the occurrence of a catastrophe. Epidemiology patterns of ascending thoracic aortic dilations/aneurysms remain understudied, whereas the risk assessment of it may be improved. The electronic databases PubMed/Medline 1966–2022, Web of Science 1975–2022, Scopus 1975–2022, and RSCI 1994–2022 were searched. The current guidelines recommend a purely aortic diameter-based assessment of the thoracic aortic aneurysm risk, but over 80% of the ascending aorta dissections occur at a size that is lower than the recommended threshold of 55 mm. Moreover, a 55 mm diameter criterion could exclude a vast majority (up to 99%) of the patients from preventive surgery. The authors review several visualization-based and alternative approaches which are proposed to better predict the risk of dissection in patients with borderline dilated thoracic aorta. The imaging-based assessments of the biomechanical aortic properties, the Young’s elastic modulus, the Windkessel function, compliance, distensibility, wall shear stress, pulse wave velocity, and some other parameters have been proposed to improve the risk assessment in patients with ascending thoracic aortic aneurysm. While the authors do not argue for shifting the diameter threshold to the left, they emphasize the need for more personalized solutions that integrate the imaging data with the patient’s genotypes and phenotypes in this heterogeneous pathology.

Thoracic Aortic Dilation: Implications for Physical Activity and Sport Participation

Thoracic aortic dilatation is a progressive condition that results from aging and many pathological conditions (i.e., connective tissue, inflammatory, shear stress disorders, severe valvular heart disease) that induce degenerative changes in the elastic properties, leading to the loss of elasticity and compliance of the aortic wall. Mild aortic root enlargement may be also observed in athletes and is considered as a normal adaptation to regular exercise training. On the other hand, high-intensity physical activity in individuals with a particular genetic substrate, such as those carrying gene variants associated with Marfan syndrome or other inherited aortopathies, can favor an excessive aortic enlargement and trigger an acute aortic dissection. The evaluation of the aortic valve and aortic root diameters, as well as the detection of a disease-causing mutation for inherited aortic disease, should be followed by a tailored decision about sport eligibility. In addition, the risk of aortic complications associated with sport in patients with genetic aortic disease is poorly characterized and is often difficult to stratify for each individual athlete. This review aims to describe the relationship between regular physical activity and aortic dilation, focusing on patients with bicuspid aortic valve and inherited aortic disease, and discuss the implications in terms of aortic disease progression and sport participation.

Toward standard abbreviations and acronyms for use in articles on aortic disease

Objectives

Academic medical literature is fraught with complex article-specific acronyms and abbreviations that can impair communication and make reading arduous. Our goal is to ease frustration with bespoke, inconsistent, and variable sets of abbreviations that currently exist for common aorta-related terminology (eg, anatomy, imaging, disease, and therapy). We hope to ease reading and improve communication in the aortic sphere of cardiovascular literature.

Methods

We reviewed a total of 205 published references related to aortic disease, including a systematic review of aorta-related articles in the Journal of Thoracic and Cardiovascular Surgery from the years 2020 and 2021. The array of variable definitions, abbreviations, and acronyms encountered in different papers that refer to the same terminology was striking, revealing that there were few standardized abbreviations in the aortic literature. We cataloged these terms, their associated abbreviations, and their frequency of use, and compiled a list of proposed standard abbreviations for commonly used terms that could be implemented uniformly in articles written about aortic diseases.

Results

We present suggested acronyms and abbreviations for common terminology related to the aorta. It is anticipated that this standard list will evolve over time as the literature and technology of the field grows and develops.

Conclusions

A proposed standard set of acronyms and abbreviations for aorta-related terminology is provided that, if found useful, could be implemented broadly in the aortic literature.

Can We Better Differentiate Type A Dissections: Evaluating the Role of Aortic Ratios

OBJECTIVES

Type A aortic dissection (ATAAD) is hypothesised as a progression of aneurysmal dilation, but 60% of patients in the International Registry of Acute Aortic Dissection (iRAD) registry had a maximum aortic diameter (MAD)<55 mm. We aim to demonstrate that size ratios and aortic wall stress, assessed using a simplified markers, are unique to aortic patients who have had adverse events (ATAAD) compared to those who have not (thoracic aortic aneurysm [TAA]).

METHODS

A retrospective cohort analysis of patients who underwent aortic intervention at Waikato Hospital, New Zealand between 2015-2020, comparing dissection (ATAAD) to TAA patients. MAD; ratio of MAD to standardised-points within the aorta; and MAD-to-height collected from computed tomography (CT)-scans of all patients was undertaken. Receiver operating characteristic (ROC)-analysis to determine cut-off point for each marker was undertaken together with multivariable logistic regression comparing both cohorts, cross-validated by propensity-score matched analysis.

RESULTS

Cohort of 215 patients, 78 (36.3%) ATAAD and 137 (63.7%) TAA; median age at intervention 63.3 years, 52 (24.2%) females, both cohorts matched for size. Using the entire cohort, the MAD: sinus of Valsalva (SoV) ratio>1.06 (cut-off value) had 4.5-times greater association with ATAAD (95%CI 1.46-13.8) and a 0.1-unit increased conferred 1.45-times greater association with ATAAD (95%CI 1.00-2.08). MAD>55 mm only seen in 33.3% of ATAAD (n=26/78), and not associated with ATAAD (OR 1.88, 95%CI 0.64-5.51). Compared to MAD, MAD:SoV ratio had greater sensitivity (33% vs 73%), lower number-needed-to-treat (17.9 vs 2.7) and superior discrimination (area under the curve [AUC] 0.54 vs 0.71). Findings were consistent with propensity score matched analysis.

CONCLUSIONS

MAD:SoV ratio significantly correlates with ATAAD (4.5 times), with superior sensitivity, discrimination, and attributable-risk-percentage compared to MAD alone.

Association of dissected ascending aorta diameter with preoperative adverse events in patients with acute type A aortic dissection

BACKGROUND

Acute type A aortic dissection (ATAAD) is a life-threatening disease associated with high morbidity and mortality.

AIM

To evaluate the diameter of dissected ascending aorta in patients diagnosed with ATAAD and whether the aortic diameter is associated with preoperative adverse events.

METHODS

A total of 108 patients diagnosed with ATAAD who underwent emergency operation under hypothermic circulatory arrest were enrolled in this study. Demographic characteristics and perioperative data were recorded. In all patients, preoperative chest and abdomen computed tomography (CT) scans were performed.

RESULTS

Median age of the patients was 61.5 (52.5-70.5) years and median body mass index (BMI) was 28.2 (25.1-32.6) cm². The number of female patients was 37 (25%). Median diameter of the ascending aorta was 5.0 (4.5-6) cm and 53.8% of the patients had an aortic diameter < 5.0 cm, while 32.3% of the patients had an aortic diameter of 4.5cm and 72.0% had an ascending aorta diameter < 5.5 cm. The diameter of the ascending aorta did not differ in patients with vs without preoperative adverse events: Preoperative neurological dysfunction (P = 0.53) and hemodynamic instability (P = 0.43). Median age of patients with preoperative hemodynamic instability was 65 (57.5-74) years, while it was 60 (51-68) years in patients without (P = 0.04)

CONCLUSION

Although current guidelines suggest replacing the ascending aorta with a diameter > 5.5 cm, most of the patients with ATAAD had an aortic diameter of less than 5.5 cm. The diameter of the ascending aorta in patients diagnose with ATAAD is not associated with preoperative adverse events.

4D Flow MRI in Ascending Aortic Aneurysms: Reproducibility of Hemodynamic Parameters

(1) Background: Aorta hemodynamics have been associated with aortic remodeling, but the reproducibility of its assessment has been evaluated marginally in patients with thoracic aortic aneurysm (TAA). The current study evaluated intra- and interobserver reproducibility of 4D flow MRI-derived hemodynamic parameters (normalized flow displacement, flow jet angle, wall shear stress (WSS) magnitude, axial WSS, circumferential WSS, WSS angle, vorticity, helicity, and local normalized helicity (LNH)) in TAA patients; (2) Methods: The thoracic aorta of 20 patients was semi-automatically segmented on 4D flow MRI data in 5 systolic phases by 3 different observers. Each time-dependent segmentation was manually improved and partitioned into six anatomical segments. The hemodynamic parameters were quantified per phase and segment. The coefficient of variation (COV) and intraclass correlation coefficient (ICC) were calculated; (3) Results: A total of 2400 lumen segments were analyzed. The mean aneurysm diameter was 50.8 ± 2.7 mm. The intra- and interobserver analysis demonstrated a good reproducibility (COV = 16–30% and ICC = 0.84–0.94) for normalized flow displacement and jet angle, a very good-to-excellent reproducibility (COV = 3–26% and ICC = 0.87–1.00) for all WSS components, helicity and LNH, and an excellent reproducibility (COV = 3–10% and ICC = 0.96–1.00) for vorticity; (4) Conclusion: 4D flow MRI-derived hemodynamic parameters are reproducible within the thoracic aorta in TAA patients.

Geometric, Biomechanic and Haemodynamic Aortic Abnormalities Assessed by 4D Flow Cardiovascular Magnetic Resonance in Patients Treated by TEVAR Following Blunt Traumatic Thoracic Aortic Injury

OBJECTIVE

Thoracic endovascular aortic repair (TEVAR) is widely used for the treatment of patients with blunt traumatic thoracic aortic injury (BTAI). However, aortic haemodynamic and biomechanical implications of this intervention are poorly investigated. This study aimed to assess whether patients treated by TEVAR following BTAI have thoracic aortic abnormalities in geometry, stiffness, and haemodynamics.

METHODS

Patients with BTAI treated by TEVAR at Vall d'Hebron Hospital between 1999 and 2019 were compared with propensity score matched healthy volunteers (HVs). All subjects underwent cardiovascular magnetic resonance (CMR) comprising a 4D flow CMR sequence. Spatially resolved aortic diameter, length, volume, and curvature were assessed. Pulse wave velocity, distensibility, and longitudinal strain (all measurements of aortic stiffness) were determined regionally. Moreover, advanced haemodynamic descriptors were quantified: systolic flow reversal ratio (SFRR), quantifying backward flow during systole, and in plane rotational flow (IRF), measuring in plane strength of helical flow.

RESULTS

Twenty-six BTAI patients treated by TEVAR were included and matched with 26 HVs. They did not differ in terms of age, sex, and body surface area. Patients with TEVAR had a larger and longer ascending aorta (AAo) and marked abnormalities in local curvature. Aortic stiffness was greater in the aortic segments proximal and distal to TEVAR compared with controls. Moreover, TEVAR patients presented strongly altered flow dynamics compared with controls: a reduced IRF from the distal AAo to the proximal descending aorta and an increased SFRR in the whole thoracic aorta. These differences persisted adjusting for cardiovascular risk factors and were independent of time elapsed since TEVAR implantation.

CONCLUSION

At long term follow up, previously healthy patients who underwent TEVAR implantation following BTAI had increased diameter, length and volume of the ascending aorta, and increased aortic stiffness and abnormal flow patterns in the whole thoracic aorta compared with matched controls. Further studies should address whether these alterations have clinical implications.

Progress in aorta and peripheral cardiovascular disease research

Although coronavirus disease 2019 seems to be the leading topic in research number of outstanding studies have been published in the field of aorta and peripheral vascular diseases likely affecting our clinical practice in the near future. This review article highlights key research on vascular diseases published in 2020. Some studies have shed light in the pathophysiology of aortic aneurysm and dissection suggesting a potential role for kinase inhibitors as new therapeutic options. A first proteogenomic study on fibromuscular dysplasia (FMD) revealed a promising novel disease gene and provided proof-of-concept for a protein/lipid-based FMD blood test. The role of NADPH oxidases in vascular physiology, and particularly endothelial cell differentiation, is highlighted with potential for cell therapy development. Imaging of vulnerable plaque has been an intense field of research. Features of plaque vulnerability on magnetic resonance imaging as an under-recognized cause of stroke are discussed. Major clinical trials on lower extremity peripheral artery disease have shown added benefit of dual antithrombotic (aspirin plus rivaroxaban) treatment.

Characterization of Ascending Aortic Flow in Patients With Degenerative Aneurysms: A 4D Flow Magnetic Resonance Study

OBJECTIVES

Degenerative thoracic aortic aneurysm (TAA) patients are known to be at risk of life-threatening acute aortic events. Guidelines recommend preemptive surgery at diameters of greater than 55 mm, although many patients with small aneurysms show only mild growth rates and more than half of complications occur in aneurysms below this threshold. Thus, assessment of hemodynamics using 4-dimensional flow magnetic resonance has been of interest to obtain more insights in aneurysm development. Nonetheless, the role of aberrant flow patterns in TAA patients is not yet fully understood.

MATERIALS AND METHODS

A total of 25 TAA patients and 22 controls underwent time-resolved 3-dimensional phase contrast magnetic resonance imaging with 3-directional velocity encoding (ie, 4-dimensional flow magnetic resonance imaging). Hemodynamic parameters such as vorticity, helicity, and wall shear stress (WSS) were calculated from velocity data in 3 anatomical segments of the ascending aorta (root, proximal, and distal). Regional WSS distribution was assessed for the full cardiac cycle.

RESULTS

Flow vorticity and helicity were significantly lower for TAA patients in all segments. The proximal ascending aorta showed a significant increase in peak WSS in the outer curvature in TAA patients, whereas WSS values at the inner curvature were significantly lower as compared with controls. Furthermore, positive WSS gradients from sinotubular junction to midascending aorta were most prominent in the outer curvature, whereas from midascending aorta to brachiocephalic trunk, the outer curvature showed negative WSS gradients in the TAA group. Controls solely showed a positive gradient at the inner curvature for both segments.

CONCLUSIONS

Degenerative TAA patients show a decrease in flow vorticity and helicity, which is likely to cause perturbations in physiological flow patterns. The subsequent differing distribution of WSS might be a contributor to vessel wall remodeling and aneurysm formation.

Root Reimplantation and Aortic Annuloplasty With External Ring in Bicuspid Aortic Valve: An Anatomical Comparison

Aortic annuloplasty has demonstrated to be a protective factor in valve-sparing root replacement and aortic valve repair. Both reimplantation for aortic root aneurysms and external ring annuloplasty for isolated aortic regurgitation have demonstrated good long-term results. The aim of this anatomical study is to compare aortic reimplantation with Valsalva graft with aortic external ring annuloplasty in bicuspid aortic valves, analyzing their morphological features with CT scan. We selected 56 patients with bicuspid aortic valve who underwent reimplantation procedure with Valsalva graft or external ring annuloplasty; after propensity-matching, 2 homogeneous groups of 10 patients each were obtained. Through multiplanar ECG-gated CT-Scan reconstructions, pre- and postoperative, aortic annular, and valve geometrical characteristics were compared (diameters, perimeter, area and ellipticity index for the annulus; effective height, coaptation length and commissural height for the valve). Aortic root volume was also analyzed. Postoperative comparison of the two groups showed similar geometric features of the aortic annulus in terms of major and minor diameters, perimeter, area and ellipticity index. Analysis of valve's parameters showed similar results in terms of effective height and coaptation length (respectively 10.9 ± 2.1 mm and 7.5 ± 1.9 mm in External Ring group and 10.1 ± 2.0 mm and 7.6 ± 1.6 mm in the Reimplantation group). Both techniques achieve an efficient annuloplasty with similar anatomical results on bicuspid the aortic valves. The stability of these results needs to be confirmed by long-term clinical and echocardiographic follow-up.

Intra-Operative Video-Based Measurement of Biaxial Strains of the Ascending Thoracic Aorta

Local biaxial deformation measurements are essential for the in-depth investigation of tissue properties and remodeling of the ascending thoracic aorta, particularly in aneurysm formation. Current clinical imaging modalities pose limitations around the resolution and tracking of anatomical markers. We evaluated a new intra-operative video-based method to assess local biaxial strains of the ascending thoracic aorta. In 30 patients undergoing open-chest surgery, we obtained repeated biaxial strain measurements, at low- and high-pressure conditions. Precision was very acceptable, with coefficients of variation for biaxial strains remaining below 20%. With our four-marker arrangement, we were able to detect significant local differences in the longitudinal strain as well as in circumferential strain. Overall, the magnitude of strains we obtained (range: 0.02–0.05) was in line with previous reports using other modalities. The proposed method enables the assessment of local aortic biaxial strains and may enable new, clinically informed mechanistic studies using biomechanical modeling as well as mechanobiological profiling.

3D morphometric analysis of ascending aorta as an adjunctive tool to predict type A acute aortic dissection

Background

Acute type A aortic dissection (AAAD) is a pathological process that implicates the ascending aorta and represents a surgical emergency burdened by high mortality if not promptly treated in the first hours of onset. Despite best efforts, the annual incidence rates of aortic dissection has remained stable over the past decades. We measured aortic dimensions (aortic diameters, area, length and volume) using 3D multiplanar reconstruction imaging with the purpose of refining the risk- morphology for AAAD.

Methods

Computerized tomography angiography studies of three groups were compared retrospectively: patients affected by AAAD (AAAD group; n=71), patients affected by aortic aneurysm and subsequently subjected to ascending aorta replacement (Aneurysm, n=77) and a healthy aorta’s group (Control, n=75).

Results

Mean diameters of AAAD (4.9 cm) and Aneurysm (5.1 cm) aortas were significantly larger than those of the control group (3.4 cm). In AAAD patients, an ascending aorta diameter greater than 5.5 cm was observed in 18% of patients. Multiple comparisons showed statistically significant differences among mean of the ratio of aortic root area to height between the three groups (P<0.001). In frontal and sagittal planes, the length of the ascending aorta was significantly greater in patients affected by aortic pathology (AAAD and aneurysm) than in the control group (P<0.001). Significant differences were confirmed when indexing the aortic length to patient’s height and BSA, and the aortic volume to patient’s BSA.

Conclusions

Maximum transverse diameter, considered separately, is not the best predictor of aortic dissection. In our opinion, the introduction into clinical practice of measurements of the area, length, and volume of the aorta, as absolute or indexed values, could improve the selection of patients who would benefit from preventive surgical aortic replacement.

Implications of abnormal ascending aorta geometry for risk prediction of acute type A aortic dissection

OBJECTIVES

Recently, increased length of the ascending aorta has been suggested as a possible risk factor for acute type A aortic dissection (ATAAD). Our goal was to identify measurable aortic geometrical characteristics associated with elongation that could differentiate ATAAD from uncomplicated aortic dilation (>45 mm).

METHODS

In angiographic computed tomography scans performed in 180 patients having cardiac surgery, aortic diameters, root length, length of the ascending aorta at both the centreline and the greater curvature (convexity) and the root-ascending (root-asc) angle (that between the root axis and the axis of the ascending tract) and the ascending-arch (asc-arch) angle (that between the axis of the ascending aorta and the arch axis) were measured and compared among 3 patient groups: normal aorta (diameter < 45 mm), dilation/aneurysm (>45 mm) and ATAAD. Correlations between diameters and angles, diameters and lengths and lengths and angles were analysed; multivariable analysis including geometrical factors was performed to identify independent predictors of ATAAD.

RESULTS

Both patients with aneurysms and patients with ATAAD showed significantly elongated ascending aortas (P < 0.001 vs normal). However, in the aneurysms, the root-asc angle (136° ± 20° vs 147° ± 17°; P < 0.001) and in ATAAD the asc-arch angle were uniquely narrower than that in the normal aorta (116° ± 11° vs 132° ± 19°; P < 0.001). All patients with an ATAAD had an asc-arch angle ≤130°. Both in patients with ATAAD and in those without ATAAD, narrowing of the asc-arch angle was associated with elongation of the root segment (P < 0.001). In multivariable analysis, the asc-arch angle and the total length of the ascending aorta (root + tubular) were significant predictors of ATAAD.

CONCLUSIONS

The asc-arch angle is a promising measurement that could help predict aortic dissection along with aortic diameter and length: further verification is warranted.

Determining the optimal interval for imaging surveillance of ascending aortic aneurysms

Background

Cardiovascular guidelines recommend (bi-)annual computed tomography (CT) or magnetic resonance imaging (MRI) for surveillance of the diameter of thoracic aortic aneurysms (TAAs). However, no previous study has demonstrated the necessity for this approach. The current study aims to provide patient-specific intervals for imaging follow-up of non-syndromic TAAs.

Methods

A total of 332 patients with non-syndromic ascending aortic aneurysms were followed over a median period of 6.7 years. Diameters were assessed using all available imaging techniques (echocardiography, CT and MRI). Growth rates were calculated from the differences between the first and last examinations. The diagnostic accuracy of follow-up protocols was calculated as the percentage of subjects requiring pre-emptive surgery in whom timely identification would have occurred.

Results

The mean growth rate in our population was 0.2 ± 0.4 mm/year. The highest recorded growth rate was 2.0 mm/year, while 40.6% of patients showed no diameter expansion during follow-up. Females exhibited significantly higher growth rates than men (0.3 ± 0.5 vs 0.2 ± 0.4 mm/year, p = 0.007). Conversely, a bicuspid aortic valve was not associated with more rapid aortic growth. The optimal imaging protocol comprises triennial imaging of aneurysms 40–49 mm in diameter and yearly imaging of those measuring 50–54 mm. This strategy is as accurate as annual follow-up, but reduces the number of imaging examinations by 29.9%.

Conclusions

In our population of patients with non-syndromic TAAs, we found aneurysm growth rates to be lower than those previously reported. Yearly imaging does not lead to changes in the management of small aneurysms. Thus, lower imaging frequencies might be a good alternative approach.

Prescreening and treatment of aortic dissection through an analysis of infinite-dimension data

Background

Aortic dissection (AD) is one of the most catastrophic aortic diseases associated with a high mortality rate. In contrast to the advances in most cardiovascular diseases, both the incidence and in-hospital mortality rate of AD have experienced deviant increases over the past 20 years, highlighting the need for fresh prospects on the prescreening and in-hospital treatment strategies.

Methods

Through two cross-sectional studies, we adopt image recognition techniques to identify pre-disease aortic morphology for prior diagnoses; assuming that AD has occurred, we employ functional data analysis to determine the optimal timing for BP and HR interventions to offer the highest possible survival rate.

Results

Compared with the healthy control group, the aortic centerline is significantly more slumped for the AD group. Further, controlling patients’ blood pressure and heart rate according to the likelihood of adverse events can offer the highest possible survival probability.

Conclusions

The degree of slumpness is introduced to depict aortic morphological changes comprehensively. The morphology-based prediction model is associated with an improvement in the predictive accuracy of the prescreening of AD. The dynamic model reveals that blood pressure and heart rate variations have a strong predictive power for adverse events, confirming this model’s ability to improve AD management.

Supplementary Information

The online version contains supplementary material available at (10.1186/s13040-021-00249-8).

New indicators for systematic assessment of aortic morphology: a narrative review

In order to prevent the occurrence of aortic adverse events in ascending thoracic aortic aneurysm patients, preventive surgery is the sole option in case of large aneurysm. Identifying high-risk patients timely and accurately requires effective predictive indicators of aortic adverse events and accurate risk stratification thresholds. Absolute diameter measured after a single imaging examination, which has been used as the predictive indicator for decades, has been proved to be ineffective for risk stratification in moderately dilated aorta. Previously, new indicators combining absolute diameters with personalized parameters have been reported to show better predictive power of aortic adverse events than absolute diameters by correcting the effect of these parameters on the diameters. Meanwhile, combining three-dimensional parameters to formulate risk stratification thresholds not only may characterize the aortic risk morphology more precisely, but also predict aortic adverse events more accurately. These new indicators may provide more systematic assessment methods of patients’ risk, formulate more personalized intervention strategies for ascending thoracic aortic aneurysm patients, and also provide a basis for researchers to develop more accurate and effective risk thresholds. We also highlight that the algorithm obtained by combining multiple indicators may be a better choice compared with single indicator, but this still requires the support of more evidence. Due to the particularity of syndromic aortic disease, whether these new indicators can be used for its risk stratification is still uncertain. Therefore, the scope of this manuscript does not include this kind of disease.