Diameters of the thoracic aorta throughout life as measured with helical computed tomography

Unsupervised machine learning for risk stratification and identification of relevant subgroups of ascending aorta dimensions using cardiac CT and clinical data

The potential of precision population health lies in its capacity to utilize robust patient data for customized prevention and care targeted at specific groups. Machine learning has the potential to automatically identify clinically relevant subgroups of individuals, considering heterogeneous data sources. This study aimed to assess whether unsupervised machine learning (UML) techniques could interpret different clinical data to uncover clinically significant subgroups of patients suspected of coronary artery disease and identify different ranges of aorta dimensions in the different identified subgroups. We employed a random forest-based cluster analysis, utilizing 14 variables from 1170 (717 men/453 women) participants. The unsupervised clustering approach successfully identified four distinct subgroups of individuals with specific clinical characteristics, and this allows us to interpret and assess different ranges of aorta dimensions for each cluster. By employing flexible UML algorithms, we can effectively process heterogeneous patient data and gain deeper insights into clinical interpretation and risk assessment.

Development of idealized human aortic models for in vitro and in silico hemodynamic studies

Background

The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies.

Objective

This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings.

Methods

Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations.

Results

Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models.

Conclusions

The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.

Computational Investigation of Vessel Injury Due to Catheter Tracking During Transcatheter Aortic Valve Replacement

Catheter reaction forces during transcatheter valve replacement (TAVR) may result in injury to the vessel or plaque rupture, triggering distal embolization or thrombosis. In vitro test methods represent the arterial wall using synthetic proxies to determine catheter reaction forces during tracking, but whether they can account for reaction forces within the compliant aortic wall tissue in vivo is unknown. Moreover, the role of plaque inclusions is not well understood. Computational approaches have predicted the impact of TAVR positioning, migration, and leaflet distortion, but have not yet been applied to investigate aortic wall reaction forces and stresses during catheter tracking. In this study, we investigate the role that catheter design and aorta and plaque mechanical properties have on the risk of plaque rupture during TAVR catheter delivery. We report that, for trackability testing, a rigid test model provides a reasonable estimation of the peak reaction forces experienced during catheter tracking within compliant vessels. We investigated the risk of rupture of both the aortic tissue and calcified plaques. We report that there was no risk of diseased aortic tissue rupture based on an accepted aortic tissue stress threshold (4.2 MPa). However, we report that both the aortic and plaque tissue exceed a rupture stress threshold (300 kPa) with and without the presence of stiff and soft plaque inclusions. We also highlight the potential risks associated with shorter catheter tips during catheter tracking and demonstrate that increasing the contact surface will reduce peak contact pressures experienced in the tissue.

Differential expansion and outcomes of ascending and descending degenerative thoracic aortic aneurysms

OBJECTIVE

To evaluate expansion of degenerative thoracic aortic aneurysms (TAAs) and compare results between ascending and descending TAAs.

METHODS

Among patients with diagnosis of degenerative TAA (1995-2015) in Olmsted County, we studied those having at least 2 computed tomography scans of TAA throughout the follow-up. Patients were classified as ascending or descending groups according to the segment where the maximal aortic diameter was measured. Primary end points were expansion rates and factors associated with TAA growth.

RESULTS

We investigated 137 patients, 70 (51.1%) of whom were women; 78 (56.9%) were in the ascending and 59 (43.1%) were in the descending group. Median baseline maximal aortic diameter was 48.5 mm (interquartile range, 47.0-49.9 mm) for ascending and 42.4 mm (interquartile range, 40.0-45.4 mm) for descending group (P < .001). Median expansion rate was higher in the descending than the ascending group (2.0 mm/year [interquartile range, 0.9-3.2 mm/year] vs 0.2 mm/year [IQR, 0.1-0.6 mm/year]; P < .001). Aneurysm in the descending aorta and larger baseline maximal aortic diameter were independently associated with TAA expansion. Advanced age and chronic obstructive pulmonary disease but not aneurysm size or location were independently associated with overall mortality (P < .05). Aneurysm in the descending aorta was associated with aortic-related events (P < .05).

CONCLUSIONS

Degenerative TAAs under surveillance expand slowly. Descending TAA and larger baseline maximal aortic diameter were independently associated with more rapid TAA expansion, but these factors did not influence all-cause mortality.

Aortic valve neocuspidization and bioprosthetic valves: Evaluating turbulence haemodynamics

Aortic valve disease is often treated with bioprosthetic valves. An alternative treatment is aortic valve neocuspidization which is a relatively new reparative procedure whereby the three aortic cusps are replaced with patient pericardium or bovine tissues. Recent research indicates that aortic blood flow is disturbed, and turbulence effects have yet to be evaluated in either bioprosthetic or aortic valve neocuspidization valve types in patient-specific settings. The aim of this study is to better understand turbulence production in the aorta and evaluate its effects on laminar and turbulent wall shear stress. Four patients with aortic valve disease were treated with either bioprosthetic valves (n=2) or aortic valve neocuspidization valvular repair (n=2). Aortic geometries were segmented from magnetic resonance images (MRI), and 4D flow MRI was used to derive physiological inlet and outlet boundary conditions. Pulsatile large-eddy simulations were performed to capture the full range of laminar, transitional and turbulence characteristics in the aorta. Turbulence was produced in all aortas with highest levels occurring during systolic deceleration. In the ascending aorta, turbulence production is attributed to a combination of valvular skew, valvular eccentricity, and ascending aortic dilation. In the proximal descending thoracic aorta, turbulence production is dependent on the type of arch-descending aorta connection (e.g., a narrowing or sharp bend) which induces flow separation. Laminar and turbulent wall shear stresses are of similar magnitude throughout late systolic deceleration and diastole, although turbulent wall shear stress magnitudes exceed laminar wall shear stresses between 27.3% and 61.1% of the cardiac cycle. This emphasises the significance of including turbulent wall shear stress to improve our comprehension of progressive arterial wall diseases. The findings of this study recommend that aortic valve treatments should prioritise minimising valvular eccentricity and skew in order to mitigate turbulence generation.

Toward Extending Concentric Tube Robot Kinematics for Large Clearance and Impulse Curvature

Concentric Tube Robots (CTRs) have been proposed to operate within the unstructured environment for minimally invasive surgeries. In this letter, we consider the operation scenario where the tubes travel inside the channels with a large clearance or large curvature, such as aortas or industrial pipes. Accurate kinematic modeling of CTRs is required for the development of motion planning and control within these operation scenarios. To this end, we extended the conventional CTR kinematics model to a more general case with large tube-to-tube clearance and large centerline curvature. Numerical simulations and experimental validations are conducted to compare our model with respect to the conventional CTR kinematic model. In the physical experiments, our proposed model achieved a tip position error of 1.53 mm in the 2D planer case and 3.86 mm in 3D case, outperforming the state-of-the-art model by 71% and 61%, respectively.

Assessing the role of an artificial intelligence assessment tool for thoracic aorta diameter on routine chest CT

OBJECTIVE

To assess the diagnostic accuracy and clinical impact of automated artificial intelligence (AI) measurement of thoracic aorta diameter on routine chest CT.

METHODS

A single-centre retrospective study involving three cohorts. 210 consecutive ECG-gated CT aorta scans (mean age 75 ± 13) underwent automated analysis (AI-Rad Companion Chest CT, Siemens) and were compared to a reference standard of specialist cardiothoracic radiologists for accuracy measuring aortic diameter. A repeated measures analysis tested reporting consistency in a second cohort (29 patients, mean age 61 ± 17) of immediate sequential pre-contrast and contrast CT aorta acquisitions. Potential clinical impact was assessed in a third cohort of 197 routine CT chests (mean age 66 ± 15) to document potential clinical impact.

RESULTS

AI analysis produced a full report in 387/436 (89%) and a partial report in 421/436 (97%). Manual vs AI agreement was good to excellent (ICC 0.76-0.92). Repeated measures analysis of expert and AI reports for the ascending aorta were moderate to good (ICC 0.57-0.88). AI diagnostic performance crossed the threshold for maximally accepted limits of agreement (>5 mm) at the aortic root on ECG-gated CTs. AI newly identified aortic dilatation in 27% of patients on routine thoracic imaging with a specificity of 99% and sensitivity of 77%.

CONCLUSION

AI has good agreement with expert readers at the mid-ascending aorta and has high specificity, but low sensitivity, at detecting dilated aortas on non-dedicated chest CTs.

ADVANCES IN KNOWLEDGE

An AI tool may improve the detection of previously unknown thoracic aorta dilatation on chest CTs vs current routine reporting.

The association between pulmonary artery enlargement and mortality in an Emergency Department population undergoing computed tomography pulmonary angiography

Findings of an enlarged pulmonary artery diameter (PAd) and increased pulmonary artery to ascending aorta ratio (PA:AA) on contrast-enhanced computed tomography pulmonary angiography (CTPA) are associated with increased mortality in particular groups of patients with cardiopulmonary disease. However, the frequency and prognostic significance of these incidental findings has not been studied in unselected patients evaluated in the Emergency Department (ED). This study aims to determine the prevalence and associated prognosis of enlarged pulmonary artery measurements in an ED cohort. We measured PA and AA diameters on 990 CTPA studies performed in the ED. An enlarged PA diameter was defined as >27 mm in females and >29 mm in males, while an increased PA:AA was defined as >0.9. Poisson regression was performed to calculate prevalence ratios for relevant comorbidities, and multivariable Cox regression was performed to calculate hazard ratios (HR) for mortality of patients with enlarged pulmonary artery measurements. An enlarged PAd was observed in 27.9% of 990 patients and was more commonly observed in older patients and in patients with obesity or heart failure. Conversely, PA:AA was increased in 34.2% of subjects, and was more common in younger patients and those with peripheral vascular disease or obesity. After controlling for age, sex, and comorbidities, both enlarged PAd (HR 1.29, 95% CI 1.00-1.68, p = 0.05) and PA:AA (HR 1.70, 95% CI 1.31-2.22 p < 0.01) were independently associated with mortality. In sum, enlarged PAd and increased PA:AA are common in patients undergoing CTPAs in the ED setting and both are independently associated with mortality.

Evaluation of the aorta in infants with simple or complex coarctation of the aorta using CT angiography

Objective

To assess aortic dilatation and determine its related factors in infants with coarctation of the aorta (CoA) by using computed tomography angiography (CTA).

Methods

The clinical data of 55 infantile patients with CoA diagnosed by CTA were analyzed retrospectively. Aortic diameters were measured at six different levels and standardized as Z scores based on the square root of body surface area. The results of simple and complex CoA were compared. Univariate and multivariate logistic regression were used to analyze the effects of sex, age, hypertension, degree of coarctation, CoA type, bicuspid aortic valve (BAV), and other factors related to aortic dilatation.

Results

In total, 52 infant patients with CoA were analyzed, including 22 cases of simple CoA and 30 cases of complex CoA. The ascending aorta of the infants in the simple CoA group and the complex CoA group were dilated to different degrees, but the difference was not statistically significant (50.00% vs. 73.33%, P = 0.084, and 2.05 ± 0.40 vs. 2.22 ± 0.43 P = 0.143). The infants in the complex CoA group had more aortic arch hypoplasia than those in the simple CoA group (33.33% vs. 9.09%, P = 0.042). Compared to the ventricular septal defect (VSD) group, the Z score of the ascending aorta in the CoA group was significantly higher than that in the VSD group (P = 0.023 and P = 0.000). A logistic retrospective analysis found that an increased degree of coarctation (CDR value) was an independent predictor of ascending aortic dilatation (adjusted OR = 0.002; P = 0.034).

Conclusion

Infants with simple or complex CoA are at risk of ascending aortic dilatation, and the factors of ascending aortic dilatation depend on the degree of coarctation. The risk of aortic dilatation in infants with CoA can be identified by CTA.

Detection of acute thoracic aortic dissection based on plain chest radiography and a residual neural network (Resnet)

Acute thoracic aortic dissection is a life-threatening disease, in which blood leaking from the damaged inner layer of the aorta causes dissection between the intimal and adventitial layers. The diagnosis of this disease is challenging. Chest x-rays are usually performed for initial screening or diagnosis, but the diagnostic accuracy of this method is not high. Recently, deep learning has been successfully applied in multiple medical image analysis tasks. In this paper, we attempt to increase the accuracy of diagnosis of acute thoracic aortic dissection based on chest x-rays by applying deep learning techniques. In aggregate, 3,331 images, comprising 716 positive images and 2615 negative images, were collected from 3,331 patients. Residual neural network 18 was used to detect acute thoracic aortic dissection. The diagnostic accuracy of the ResNet18 was observed to be 90.20% with a precision of 75.00%, recall of 94.44%, and F1-score of 83.61%. Further research is required to improve diagnostic accuracy based on aorta segmentation.

High Prevalence of Thoracic Aortic Dilatation in Men with Previous Inguinal Hernia Repair

Background  Identifying a useful marker for thoracic aortic dilatation (TAD) could help improve informed clinical decisions, enhance diagnosis, and develop TAD screening programs. Inguinal hernia could be such a marker. This study tested the hypothesis that the thoracic aorta is larger and more often dilated in men with previous inguinal hernia repair versus nonhernia controls.

Methods  Four hundred men each with either previous inguinal hernia repair or cholecystectomy (controls) were identified to undergo chest computed tomography to measure the diameter of the thoracic aorta in the aortic root, ascending, isthmic, and descending aorta and to provide self-reported health data. Presence of TAD (root or ascending diameter > 45 mm; isthmic or descending diameter > 35 mm) and thoracic aortic diameters were compared between groups and associations explored using uni- and multivariable statistical methods.

Results  Complete data were obtained from 470/718 (65%) eligible participants. TAD prevalence was significantly higher in the inguinal hernia group: 21 (10%) versus 6 (2.4%), p  = 0.001 for proximal TAD, 29 (13%) versus 21 (8.3%), p  = 0.049 for distal TAD, and 50 (23%) versus 27 (11%), p  < 0.001 for all aortic segments combined. In multivariable analysis, previous inguinal hernia repair was independently associated with dilatation of the proximal aorta (odds ratio 5.3, 95% confidence interval 1.8–15, p  = 0.003). Contrarily, mean thoracic aortic diameters were similar (root and ascending aorta) or showed clinically irrelevant differences (isthmus and descending aorta).

Conclusion  TAD, but not increased aortic diameters on average, was common and significantly more prevalent in men with previous inguinal hernia repair. Hernia could be a marker condition associated with increased prevalence of TAD. Ultimately, TAD screening could consider hernia as a possible selection criterion.

Morphometric analysis of the inferior vena cava and its clinical correlations using abdomino-pelvic computed tomography: Series from a Jordanian population

Introduction and importance

This study aimed to determine the impact of DM, HTN and age on IVC dimensions as measured by CT scan relevant to guide interventions in a Jordanian population.

Presentation of cases

Two hundred patients were selected from those referred to the Radiology Department, Jordan University Hospital, Amman, Jordan for clinical evaluation. Patients were divided into three age subgroups. Age, sex, and comorbidities such as DM and HTN were identified and saved for later use. All dimensions of the IVC were measured using an abdomino-pelvic CT scanner.

Clinical discussion

A full morphometric analysis of the IVC would provide a better understanding of the dynamicity of the IVC in relation to its blood flow. Our results revealed that the length of the IVC was significantly shorter with age (P = 0.003). DM significantly affected the length of the IVC (P = 0.044). Hypertension also significantly affected the length of the IVC (P = 0.031), but it did not significantly affect the anterio-posterior or the transverse diameters of the IVC.

Conclusion

The length of the IVC was significantly shorter with age, DM and hypertension. Morphometric measures of the IVC are of great clinical importance as they may assist in medical or surgical intervention and follow-up.

•

Determining the main dimensions of IVC is clinically important.

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This study revealed significant variability in IVC dimensions in relation to age.

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Diabetes and hypertension are important in changing the dimensions of IVC.

The prevalence of thoracic aorta aneurysm as an important cardiovascular disease in the general population

BACKGROUND

The aorta is the largest and main artery in the body. The enlargement of the aortic diameter known as ectasia results in aneurysm. Thoracic aorta aneurysm can involve one or more segments of the aorta. Non-invasive imaging techniques play an important role in identifying patients, estimating maximal aneurysm diameter, following up patients, and detecting complications. So, this study was performed to estimate the prevalence of ascending thoracic aorta aneurysm in the general population of Iran.

METHODS

People with an abnormal aortic size (˃ 36 mm) were enrolled and subjected to diagnostic tests, and related risk factors were assessed.

RESULT

Of the 3400 people examined, 410 (12%) had abnormal aorta sizes, and 42 (1.2%) had ascending aorta aneurysm. Out of the 410 patients with elevated aorta size, 235 (57%) were males, and 175 (43%) were females. Overall, 229 patients (56%) had hypertension, and 255 (62%) were over 60 years old.

CONCLUSION

In this study, we showed that the prevalence of ascending aorta aneurysm in the general population of Iran was about 1.2%. Ascending aorta aneurysm is a threatening pathology of the aorta. The high prevalence of hypertension may explain the high incidence of aneurysm in our studied population. Therefore, it is necessary to implement an accurate screening plan to identify patients with hypertension and provide appropriate treatment and adequate follow up to patients. Patients with ascending aorta aneurysm are also recommended to modify their lifestyles.

Imaging and Surveillance of Chronic Aortic Dissection: A Scientific Statement From the American Heart Association

All patients surviving an acute aortic dissection require continued lifelong surveillance of their diseased aorta. Late complications, driven predominantly by chronic false lumen degeneration and aneurysm formation, often require surgical, endovascular, or hybrid interventions to treat or prevent aortic rupture. Imaging plays a central role in the medical decision-making of patients with chronic aortic dissection. Accurate aortic diameter measurements and rigorous, systematic documentation of diameter changes over time with different imaging equipment and modalities pose a range of practical challenges in these complex patients. Currently, no guidelines or recommendations for imaging surveillance in patients with chronic aortic dissection exist. In this document, we present state-of-the-art imaging and measurement techniques for patients with chronic aortic dissection and clarify the need for standardized measurements and reporting for lifelong surveillance. We also examine the emerging role of imaging and computer simulations to predict aortic false lumen degeneration, remodeling, and biomechanical failure from morphological and hemodynamic features. These insights may improve risk stratification, individualize contemporary treatment options, and potentially aid in the conception of novel treatment strategies in the future.

Vascular Stiffness in Aging and Disease

The goal of this review is to provide further understanding of increased vascular stiffness with aging, and how it contributes to the adverse effects of major human diseases. Differences in stiffness down the aortic tree are discussed, a topic requiring further research, because most prior work only examined one location in the aorta. It is also important to understand the divergent effects of increased aortic stiffness between males and females, principally due to the protective role of female sex hormones prior to menopause. Another goal is to review human and non-human primate data and contrast them with data in rodents. This is particularly important for understanding sex differences in vascular stiffness with aging as well as the changes in vascular stiffness before and after menopause in females, as this is controversial. This area of research necessitates studies in humans and non-human primates, since rodents do not go through menopause. The most important mechanism studied as a cause of age-related increases in vascular stiffness is an alteration in the vascular extracellular matrix resulting from an increase in collagen and decrease in elastin. However, there are other mechanisms mediating increased vascular stiffness, such as collagen and elastin disarray, calcium deposition, endothelial dysfunction, and the number of vascular smooth muscle cells (VSMCs). Populations with increased longevity, who live in areas called “Blue Zones,” are also discussed as they provide additional insights into mechanisms that protect against age-related increases in vascular stiffness. Such increases in vascular stiffness are important in mediating the adverse effects of major cardiovascular diseases, including atherosclerosis, hypertension and diabetes, but require further research into their mechanisms and treatment.

Artificial intelligence measuring the aortic diameter assist in identifying adverse blood pressure status including masked hypertension

INTRODUCTION AND OBJECTIVES

Artificial intelligence (AI) made it achievable that aortic dilation could be measured in CT images indirectly, while aortic diameter (AD) has the certain relationship with blood pressure. It was potential that the blood pressure condition be determined by AD measurement using the data obtained from a CT scanning especially in identifying masked hypertension and predicting the risk of poor control of blood pressure (BP) which was easy to elude diagnosis in clinic. We aimed to evaluate the possibility of utilizing AD by AI for predicting the risk of adverse BP status (including masked hypertension or poor BP control) and the optimal thoracic aortic position in measurement as well as the cutoff value for predicting the risk.

METHODS

Eight hundred and one patients were enrolled in our study. AI-Rad Companion Cardiovascular (K183268 FDA approved) was used to perform automatic aorta measurement in thoracic CT images at nine key positions based on AHA guidelines. Data was post processed by software from AI-Rad Companion undergone rigorous clinical validation by both FDA and CE as verification of its efficacy and usability. The AD's risk and diagnostic value was assessed in identifying hypertension in the general population, in identifying the poor BP controlled in the hypertension population, and in screening masked hypertension in the general population respectively by multiple regression analysis and receiver operating curve analysis.

RESULTS

AD measured by AI was a risk factor for adverse BP status after clinical covariates adjustment (OR = 1.02 ~ 1.26). The AD at mid descending aorta was mostly affected by BP particularly, which is optimal indicator in identifying hypertension in the general population (AUC = 0.73) and for screening masked hypertension (AUC = 0.78).

CONCLUSION

Using AI to measure the AD of the aorta, particularly at the position of mid descending aorta, is greatly valuable for identifying people with poor BP status. It will be possible to reveal more clinical information reflected by ordinary CT images and enrich the screening methods for hypertension, especially masked hypertension.PLAIN LANGUAGE SUMMARYHTN has a significant adverse effect on arterial deformation. BP and arterial dilation promote each other in a vicious circle. Arterial dilation may not be restricted by apparent fluctuations in BP and is objective evidence of an undesirable BP state. The accuracy of AD measurements by AI on chest CT images has been verified. There has not been the application of AD measurement by AI in the scene of poor BP status in clinical practice.In this study, we applied AI to measure the diameter of the aorta in nine consecutive positions. We explored the association between AD at various positions and BP levels and the possibility that AD in identifying poor BP status in different populations. We found that the AD at the MD is of great value in screening MH and evaluating the control state of BP in HTN. It will be possible to significantly expand the clinical information reflected by ordinary CT images and enrich the screening methods for HTN, especially MH.

Multidetector computed tomography study to measure thoracic aorta diameters in Egyptian population

BACKGROUND

The aorta is the largest and strongest artery in the body that plays an important role in the control of systemic vascular resistance and heart rate. Aortic diseases contribute to the wide spectrum of arterial diseases that may be diagnosed after a long period of subclinical development. Multidetector computed tomographic scanners (≥ 64 detector rows) for aortic imaging remain one of the most preferred imaging techniques for diagnosis and follow-up of aortic conditions in acute as well as chronic presentations. The aim of this study is to establish a normal reference values for aortic diameters among Egyptian population and to find which of the cardiovascular risk factors could be an independent determinant of the aortic diameters.

RESULTS

Five hundred and sixteen Egyptian individuals were enrolled in our study, the mean age was 53.5 ± 10.9, and males comprised 61.4% of the study population. Aortic root diameters measured at the annulus, sinus and STJ were 23.09 ± 2.55 mm, 33.75 ± 3.93 mm and 26.13 ± 3.05 mm, respectively. The BSA-indexed diameters were 11.70 ± 1.39, 17.10 ± 2.10 and 13.25 ± 1.65, respectively. The diameter of the tubular part of ascending aorta was 30.97 ± 4.16 mm, and the BSA-indexed diameter was 15.71 ± 2.28. The aortic diameters measured at the level of the pulmonary bifurcation were 24.56 ± 2.95 mm and 23.79 ± 2.96 mm at systolic and diastolic phases, respectively. The BSA-indexed diameters were 12.44 ± 1.52 and 12.05 ± 1.52 at systolic and diastolic phases, respectively. At the diaphragmatic level, the mean diameters were 22.39 ± 2.72 mm and 21.49 ± 2.79 mm at systolic and diastolic phases, respectively. The BSA-indexed diameters were 11.34 ± 1.43 and 10.98 ± 1.48 at systolic and diastolic phases, respectively. Age, gender, BSA, BMI and hypertension were statistically significant independent predictors of ascending and descending aortic diameters.

CONCLUSIONS

Our study established a normal reference value for thoracic aortic diameters among Egyptians using contrast enhanced MSCT aortography. Age, Gender, BSA, BMI and hypertension are the major determinants of aortic diameters.

Brain microvasculature endothelial cell orientation on micropatterned hydrogels is affected by glucose level variations

This work reports on an effort to decipher the alignment of brain microvasculature endothelial cells to physical constrains generated via adhesion control on hydrogel surfaces and explore the corresponding responses upon glucose level variations emulating the hypo- and hyperglycaemic effects in diabetes. We prepared hydrogels of hyaluronic acid a natural biomaterial that does not naturally support endothelial cell adhesion, and specifically functionalised RGD peptides into lines using UV-mediated linkage. The width of the lines was varied from 10 to 100 µm. We evaluated cell alignment by measuring the nuclei, cell, and F-actin orientations, and the nuclei and cell eccentricity via immunofluorescent staining and image analysis. We found that the brain microvascular endothelial cells aligned and elongated to these physical constraints for all line widths. In addition, we also observed that varying the cell medium glucose levels affected the cell alignment along the patterns. We believe our results may provide a platform for further studies on the impact of altered glucose levels in cardiovascular disease.

A Population-Based Study of the Incidence and Natural History of Degenerative Thoracic Aortic Aneurysms

OBJECTIVE

To investigate the incidence and natural history of degenerative thoracic aortic aneurysms (TAAs) and compare results between ascending (aTAAs) and descending TAAs (dTAAs).

PATIENTS AND METHODS

This population-based cohort study used the Rochester Epidemiology Project database from January 1, 1995, through December 31, 2015. Patients were classified as the aTAA or dTAA group.

RESULTS

Of 238 Olmsted County residents studied, 131 (55.0%) were women; 154 (64.7%) were in the aTAA group, and 84 (35.3%) were in the dTAA group. Median age was 77.0 years (interquartile range, 69.1-83.8 years). The overall age- and sex-adjusted incidence rate was 13.8 per 100,000 person-years (95% CI, 12.1 to 15.6) and varied from 9.9 in 1995 to 1999 to 19.0 in 2005 to 2009. It was 9.0 (95% CI, 7.5 to 10.4) for the aTAA and 4.9 (95% CI, 3.8 to 5.9) for the dTAA group. Overall 5-year survival was 62.5%, lower than the expected survival of 73.7% for the US 2010 census population (P<.001). The 5-year survival was 42.9% for the aTAA and 73.4% for the dTAA group (P<.001). On multivariable analysis, advanced age and smoking status were associated with all-cause mortality. The 5-year estimate of freedom from an aortic-related event was 80.0%, lower for dTAAs (67.8%) than for aTAAs (85.2%; P<.001). Maximal aortic diameter and dTAAs were associated with aortic-related events.

CONCLUSION

The incidence of TAAs was stable from 1995 to 2015 and mortality for those with TAAs remains higher than for the general population. Older age and smoking status were associated with overall mortality, whereas larger aneurysms and dTAAs were associated with aortic-related events.

Mechanobiology of the arterial tissue from the aortic root to the diaphragm

Arterial tissue microstructure and its mechanical properties directly correlate with cardiovascular diseases such as atherosclerosis and aneurysm. Experienced hemodynamic loads are the primary factor of arterial tissue remodeling. By virtue of altering hemodynamic loads along the arterial tree, respective structure-function relations will be region-dependent. Since, there is limited experimental evidence on these structure-function homeostases, the current study, aims to report microstructural and mechanical alterations along the aorta from the aortic root up to the diaphragm, where intense hemodynamic alterations take place. The ascending, arch, and descending parts of the same cadaveric aortas were investigated by histomechanical examinations. Anatomical landmarks were labeled on the specimens, and then biaxial tensile tests were conducted on samples from each region. Furthermore, area fractions of elastin and collagen were measured on stained sections of the tissue. Also, a fragmentation index of elastin tissue is proposed for quantitative measurement of ECM integrity, which correlates with the nature of experienced hemodynamic loads. For the ascending aorta and the aortic arch, different values for mechanical properties and fragmentation index are observed even in a specific cross-section of the artery. It is primarily due to the complex loading regimes and curved geometry. Conversely, microstructural and mechanical features along the descending aorta exhibited minimal variations, and hence, smooth blood flow and pressure waves are expected in this region, which is well-documented in the literature. Both of the microstructural and mechanical features of the aorta vary along the arterial tree depending on the hemodynamic and geometric complexities they incur and may shed light on the initiation of cardiovascular diseases.

Evaluation of the Effects of Aging on the Aorta Stiffness in Relation with Mineral and Trace Element Levels: an Optimized Method via Custom-Built Stretcher Device

Aortic stiffness represents the major cause of aging and tightly associated with hypertension, atherosclerosis, cardiovascular diseases, and increased mortality. Mechanical characteristics of the aorta play a vital role in the blood flow, circulation, systolic pressure, and aortic stiffness; however, the correlation of trace element and mineral levels with aortic stiffness has not been studied before. Balance in the trace elements and minerals is vital for the biological functions; however, natural aging may alter this balance. Thus, after measuring aortic stiffness of aged and young rat aortas by a custom-built stretcher device, trace element and mineral levels were evaluated via ICP-MS. Also, biomarkers of aging including blood pressure, arterial pressure glucose, insulin levels, and histochemical parameters were investigated as well. Aortic stiffness, blood glucose, plasma insulin, systolic, diastolic, and mean arterial pressure significantly increased by aging in the aorta of aged rats compared with the young ones. Also, Fe, Al, Co, Ni, Zn, Sr, Na, Mg, and K levels increased in the aged aorta samples compared with the young aorta samples of rats. Increased levels of the indicated elements may be correlated with the development and progression of aortic stiffness and vascular complications. Thus, possible mechanisms correlating aortic stiffness with the imbalance in the trace element and mineral levels should be further investigated.

A Specific Assessment of the Normal Anatomy of the Aortic Root in Relation to Age and Gender

Background

A limitation associated with coronary computed tomography angiography (CCTA) is the lack of a normal reference value for aortic root dimensions and the uncertainty of the influence of age and gender on these dimensions. The purpose of the present study was to identify the normal values and variations of aortic root dimensions in healthy individuals and investigate how gender and age affect aortic root size.

Methods

A total of 1286 healthy yellow population (52.7 ± 11.0 years, 634 male) who underwent CCTA were retrospectively included in the present study. Male and female patients were divided into seven groups according to age (< 30 years old, 30–39, 40–49, 50–59, 60–69, 70–79, ≥ 80 years old). In these age groups, we measured and compared the parameters of the aortic root.

Results

After body surface area (BSA) correction, the aortic root parameters of females were found to be greater than those of males in the 40–49 age group (P<0.05). There were no significant differences in aortic root parameters between genders in other age groups, except for the diameter of the ascending aorta, which was greater in females (P<0.05). In males, age was positively correlated with aortic root parameters (P<0.05), except for the annulus short diameter and LVOT short diameter. In females, age was positively correlated with aortic root parameters (P<0.05), except for the left coronary ostia height and the LVOT short diameter.

Conclusion

Aortic root dimensions are affected by age and gender. After BSA correction, females show larger aortic root dimensions than males, and aortic root diameters increase with age.

Deep learning method for aortic root detection

BACKGROUND

Computed tomography angiography (CTA) is a preferred imaging technique for a wide range of vascular diseases. However, extensive manual analysis is required to detect and identify several anatomical landmarks for clinical application. This study demonstrates the feasibility of a fully automatic method for detecting the aortic root, which is a key anatomical landmark in this type of procedure. The approach is based on the use of deep learning techniques that attempt to mimic expert behavior.

METHODS

A total of 69 CTA scans (39 for training and 30 for validation) with different pathology types were selected to train the network. Furthermore, a total of 71 CTA scans were selected independently and applied as the test set to assess their performance.

RESULTS

The accuracy was evaluated by comparing the locations marked by the method with benchmark locations (which were manually marked by two experts). The interobserver error was 4.6 ± 2.3 mm. On an average, the differences between the locations marked by the two experts and those detected by the computer were 6.6 ± 3.0 mm and 6.8 ± 3.3 mm, respectively, when calculated using the test set.

CONCLUSIONS

From an analysis of these results, we can conclude that the proposed method based on pre-trained CNN models can accurately detect the aortic root in CTA images without prior segmentation.

Multimodality imaging assessment of bicuspid aortic valve disease, thoracic aortic ectasia, and thoracic aortic aneurysmal disease

Acute aortic syndromes have extremely high mortality rates and those with aortic dilation are at increased risk for these often catastrophic events. Serial monitoring of patients with aortic dilation is critical to determine the appropriate timing of preventative interventions. The thoracic aorta can be imaged and measured using multiple imaging modalities including transthoracic echocardiography, transesophageal echocardiography, multidetector cardiac computed tomography, and magnetic resonance imaging. There has not been agreement on the specific techniques that should be used to measure thoracic aortic dimensions with each imaging modality, leading to potential errors and challenges in comparing changes in measurements over time. It is critical to understand the current recommendations on thoracic aortic measurements for each imaging modality and cardiovascular imaging specialists need to be explicit about the methods that they have used to derive the thoracic aortic measurements. In those at high risk for aortic pathology, such as those with connective tissue diseases or bicuspid aortic valve, a multimodality imaging strategy incorporating echocardiography including three-dimensional measurements along with cardiac computed tomography or magnetic resonance imaging should be used to establish aortic dimensions and for continued monitoring to avoid progression to acute aortic syndromes.

Dynamics of Blood Flows in Aortic Stenosis: Mild, Moderate, and Severe

Supraphysiologic high shear stresses created in calcific aortic stenosis (AS) are known to cause hemostatic abnormalities, however, the relationship between the complex blood flows over the severity of AS and hemostatic abnormalities still remains unclear. This study systematically characterized the blood flow in mild, moderate, and severe AS. A series of large eddy simulations (LES) validated by particle image velocimetry were performed on physiologically representative AS models with a peak physiologic flow condition of 18 liter per minute. Time-accurate velocity fields, transvalvular pressure gradient, and laminar viscous-and turbulent (or Reynolds) shear stresses (RSSmax) were evaluated for each degree of severity. The peak velocities of mild, moderate, and severe AS were on the order of 2.0, 4.0, and 8.0 m/s, respectively. Jet velocity in severe AS was highly skewed with extremely high velocity (as high as 8 m/s) and mainly traveled through the posterior aortic wall up to the aortic arch while still carrying a relatively high velocity, that is, >4 m/s. The mean laminar viscous wall shear stresses (WSS) for mild, moderate, and severe AS were on the order of 40, 100, and 180 Pa, respectively. The RSSmax were on the order of 260, 490, and 2,500 Pa for mild, moderate, and severe AS, respectively. This study may provide a link between altered flows in AS and hemostatic abnormalities such as acquired von Willebrand syndrome and hemolysis, thus, help diagnosing and timing of the treatment.

Realizing the actual magnitudes of aortic diameter and cardiac output: a multisensory learning approach

The conventional physiology courses consist of theoretical lectures, clinical application seminars, numerical exercises, simulations, and laboratory practices. However, in subjects that involve relevant physical quantities, even students who successfully pass exams may be unable to realize the actual quantities involved. For example, students may know what the values of the aortic diameter and cardiac output are, and they may be skilled at calculating changes in variables without being able to realize the actual physical magnitudes of the variables, resulting in limited understanding. To address this problem, here we describe and discuss simple practical exercises specifically designed to allow students to multisensory experience (touch, see, hear) the actual physical magnitudes of aortic diameter and cardiac output in adult humans at rest and exercise. The results obtained and the feedback from a student survey both clearly show that the described approach is a simple and interesting tool for motivating students and providing them with more realistic learning.

Go with the flow: modeling unique biological flows in engineered in vitro platforms

Interest in recapitulating in vivo phenomena in vitro using organ-on-a-chip technology has grown rapidly and with it, attention to the types of fluid flow experienced in the body has followed suit. These platforms offer distinct advantages over in vivo models with regards to human relevance, cost, and control of inputs (e.g., controlled manipulation of biomechanical cues from fluid perfusion). Given the critical role biophysical forces play in several tissues and organs, it is therefore imperative that engineered in vitro platforms capture the complex, unique flow profiles experienced in the body that are intimately tied with organ function. In this review, we outline the complex and unique flow regimes experienced by three different organ systems: blood vasculature, lymphatic vasculature, and the intestinal system. We highlight current state-of-the-art platforms that strive to replicate physiological flows within engineered tissues while introducing potential limitations in current approaches.

Magnetic resonance imaging assessment of aortic dilatation and distensibility in 269 patients with repaired tetralogy of Fallot

PURPOSE

To determine the prevalence and degree of aortic dilatation (A_dilatation), severity of aortic stiffness (A_stiff), factors for A_dilatation, and level of aortic root most sensitive to A_stiff in patients with repaired tetralogy of Fallot (rTOF).

MATERIALS AND METHODS

269 patients with rTOF (mean age 14.9 ± standard deviation 5.0 years) were analyzed for A_dilatation at annulus, sinus, sinotubular junction, and ascending aorta (aAo). Aortic size index was graded as Z score < 2, 2-2.99, 3-4.99 and ≥ 5. Aortic distensibility (aA_dis) was categorized according to 4 aortic levels and dilatation severity. Factors for A_dilatation and level of aortic root most sensitive to A_stiff were analyzed.

RESULTS

Sinus and aAo were the two most common sites of A_dilatation, with a prevalence of 84% and 76%, respectively. A decreased aA_dis was found (mean 5.38 ± 1.79 10^-3 mmHg^-1). aA_dis only declined significantly at the sinus level (p = 0.009). Male sex, age-at-repair and aortic regurgitation were significant factors for A_dilatation, with male sex as the strongest factor (odds ratio 2.94). There was a significant decline in aA_dis at sinus level (p = 0.002) as A_dilatation progressed.

CONCLUSIONS

We observed a high prevalence of A_dilatation and A_stiff in patients with rTOF. Male sex is the strongest factor for A_dilatation. The sinus is the most sensitive area for determining a negative aA_dis effect.

Aortic root measurement on CT: linear dimensions, aortic root area and comparison with echocardiography. A retrospective cross sectional study

OBJECTIVE

We sought to assess the different CT aortic root measurements and determine their relationship to transthoracic echocardiography (TTE).

METHODS

TTE and ECG-gated CT images were reviewed from 70 consecutive patients (mean age 54 ± 18 years; 67% male) with tricuspid aortic roots (trileaflet aortic valves) between Nov 2009 and Dec 2013. Three CT planes (coronal, short axis en face and three-chamber) were used for measurement of nine linear dimensions. TTE aortic root dimension was measured as per guidelines from the parasternal long axis view.

RESULTS

All CT short axis measurements of the aortic root had excellent reproducibility (intraclass correlation coefficient, ICC 0.96-0.99), while coronal and three-chamber planes had lower reproducibility with ICC 0.90 (95% CI 0.84-0.94) and ICC 0.92 (0.87-0.95) respectively. CT coronal and short axis maximal dimensions were systematically larger than TTE (mean 2 mm larger, p < 0.001), while CT cusp to commissure measurements were systematically smaller (CT RCC-comm mean 2 mm smaller than TTE, p < 0.001). All CT short axis measurements had excellent correlation with aortic root area with CT short axis maximal dimension marginally better than the rest (Pearson's R 0.97).

CONCLUSION

Systematic differences exist between CT and TTE dependent on the CT plane of measurement. All CT short axis measurements of the aortic root had excellent reproducibility and correlation with aortic root area with maximal dimension appearing marginally better than the rest. Our findings highlight the importance of specifying the chosen plane of aortic root measurement on CT.

ADVANCES IN KNOWLEDGE

Systematic differences in aortic root dimension exist between TTE and the various CT measurement planes. CT coronal and short axis maximal dimensions were systematically larger than TTE, while CT cusp to commissure measurements were smaller. CT readers should indicate the plane of measurement and the specific linear dimension to avoid ambiguity in follow-up and comparison.

Prediction of 3D Cardiovascular hemodynamics before and after coronary artery bypass surgery via deep learning

The clinical treatment planning of coronary heart disease requires hemodynamic parameters to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in the simulation of cardiovascular hemodynamics. However, for the patient-specific model, the complex operation and high computational cost of CFD hinder its clinical application. To deal with these problems, we develop cardiovascular hemodynamic point datasets and a dual sampling channel deep learning network, which can analyze and reproduce the relationship between the cardiovascular geometry and internal hemodynamics. The statistical analysis shows that the hemodynamic prediction results of deep learning are in agreement with the conventional CFD method, but the calculation time is reduced 600-fold. In terms of over 2 million nodes, prediction accuracy of around 90%, computational efficiency to predict cardiovascular hemodynamics within 1 second, and universality for evaluating complex arterial system, our deep learning method can meet the needs of most situations.

Thoracic aortic size in Brazilian smokers: measures using low-dose chest computed tomography anatomical and epidemiological assessment

OBJECTIVES

Thoracic aortic aneurysms (TAAs) represent one-third of the hospitalizations for aortic diseases. The prevalence rate depends on the definition of the normal size of the aorta, which is quite variable, depending on the population studied. The aim of this study was to evaluate the characteristics of the thoracic aorta of Brazilian smokers, identifying the normal size of the aorta, presence of anatomical variations, and prevalence of TAA.

MATERIALS AND METHODS

A total of 711 patients underwent radiological evaluation with low-dose computed tomography (CT) from January 2013 to July 2014 with the initial objective of lung nodule tracking. Two examiners evaluated these images, and measurements of maximum and serial diameters were performed manually in true orthogonal planes. Serial diameter measurements were taken every 2 cm in the ascending aorta and 5 cm in the descending segment. We searched for anatomical variations, aortic arch type, and correlations between anatomical characteristics, sex, body mass index, and body surface area (BSA).

RESULTS

The maximum diameters were 33.61 (standard deviation [SD] 3.88), 28.66 (SD 2.89), and 28.36 mm (SD 3.09) for the ascending segment, aortic arch, and descending segment, respectively. A positive correlation was found between male sex, age, and BSA and aorta diameter. The bovine arch was the most common variation of the aortic arch type, and we found one (0.14%) case of TAA.

CONCLUSIONS

This study with low-dose CT allowed the determination of the mean diameters of the ascending aorta, aortic arch, and descending aorta in Brazilian smokers and TAA prevalence.

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.

Sinus of Valsalva Aneurysms: A Review with Perioperative Considerations

The sinuses of Valsalva are outpouchings in the aortic root just distal to the aortic valve that serve several physiologic functions. Aneurysm of this segment of the aorta is quite rare and infrequently encountered in clinical practice. Due to the rarity of sinus of Valsalva aneurysms, there is a lack of controlled trials and most of the literature consists of case reports and series. Here, the authors review the currently available literature to discuss the anatomy and normal function of the aortic root, as well as disease pathology and diagnostic imaging considerations. Using reported cases, the authors also will discuss considerations for cardiac anesthesiologists in the perioperative period.

Artificial intelligence assistance improves reporting efficiency of thoracic aortic aneurysm CT follow-up

OBJECTIVE

Follow-up of aortic aneurysms by computed tomography (CT) is crucial to balance the risks of treatment and rupture. Artificial intelligence (AI)-assisted radiology reporting promises time savings and reduced inter-reader variabilities.

METHODS

The influence of AI assistance on the efficiency and accuracy of aortic aneurysm reporting according to the AHA / ESC guidelines was quantified based on 324 AI measurements and 1944 radiological measurements: 18 aortic aneurysm patients, each with two CT scans (arterial contrast phase, electrocardiogram-gated) with an interval of at least six months have been included. One board-certified radiologist and two residents (8/4/2 years of experience in vascular imaging) independently assessed aortic diameters at nine landmark positions. Aneurysm extensions were compared with original CT reports. After three weeks washout period, CTs were re-assessed, based on graphically illustrated AI measurements.

RESULTS

Time-consuming guideline-compliant aortic measurements revealed additional affections of the root / arch for 80 % of aneurysms that had initially been reported to be limited to the ascending aorta. AI assistance reduced mean reporting time by 63 % from 13:01 to 04:46 min including manual corrections of AI measurements (performed for 33.6 % of all measurements with predominance at the sinuses of Vasalva). AI assistance reduced total diameter inter-reader variability by 42.5 % (0.42 / 1.16 mm with / without AI assistance, mean of all patients and landmark positions, significant reduction for 6 out of 9 measuring positions). Conventional and AI-assisted quantification aneurysm progress varied to small extent (mean of 0.75 mm over all patients / landmark positions) not significantly exceeding radiologist's inter-reader variabilities.

CONCLUSIONS

Guideline-compliant aorta measurement is crucial to report detailed aneurysm extension which might affect the strategy of interventional repair. AI assistance promises improved reporting efficiency and has high potential to reduce radiologist's inter-reader variabilities that can hamper diagnostic follow-up accuracy.

KEY POINT

The time-consuming guideline-compliant aorta aneurysm assessment is crucial to report aneurysm extension in detail; AI-assisted measurement reduces reporting time, improves extension evaluation and reduces inter-reader variability.

Prevalence and Clinical Correlates of Aortic Dilation in Hypertrophic Cardiomyopathy

BACKGROUND

Aortic dilation has been associated with various cardiac conditions, although its prevalence and clinical correlates in hypertrophic cardiomyopathy (HCM) remain unclear.

OBJECTIVES

The purposes of this study were to define the prevalence of ascending aortic dilation in a large referral population of patients with HCM and to determine clinical and echocardiographic correlates of aortic dilation.

METHODS

A total of 1,698 patients with HCM underwent echocardiographic measurement of the tubular ascending aorta (proximal and midlevel) during index evaluation at a tertiary HCM referral center. End-diastolic ascending aorta dimension was indexed to body surface area, with dilation defined for the tubular ascending aorta as 2 SD above the mean (>19 mm/m²) and independently as greater than published age-, sex-, and body surface area- adjusted norms (for the sinus of Valsalva and midlevel). Aortic size and presence of aortic enlargement were correlated with clinical and echocardiographic parameters.

RESULTS

Tubular ascending aortic dilation >19 mm/m² was present in 303 patients with HCM (18%), and dilation above adjusted norms was present in 210 patients with HCM (13%). The median indexed tubular ascending thoracic aortic dimension was 16.5 (interquartile range, 14.8-18.2) mm/m². Indexed dimension increased linearly with age (R = 0.53, P < .0001). Women and patients with a history of systemic hypertension were more likely to have tubular aortic enlargement >19 mm/m² (29.8% vs 9.9% and 24.1% vs 10.5%, respectively, P < .0001 for both). Patients with obstructive physiology were more likely to have tubular aortic enlargement >19 mm/m² than those without resting or provocable obstruction (19.6% vs 14.4%, P = .007). Using adjusted norms, aortic enlargement was more frequent at the midlevel compared with the sinus of Valsalva (71% vs 29%), more common in patients with hypertension (15.4% vs 10.6%, P = .009), and more common in patients with paroxysmal atrial fibrillation (16.3% vs 11.5%, P = .036), but no other relationships remained statistically significant.

CONCLUSIONS

In this large cohort of patients with HCM, aortic dilation was common. The key correlate of tubular aortic enlargement >19 mm/m², and aortic enlargement greater than adjusted norms included a history of systemic hypertension. Given an increased prevalence of aortic dilation in HCM, further study is needed on the clinical impact of aortic dilation.

Population-Based Assessment of Aortic-Related Outcomes in Aortic Dissection, Intramural Hematoma, and Penetrating Aortic Ulcer

BACKGROUND

The aim of the study was to analyze aortic-related outcomes after diagnosis of aortic dissection (AD), intramural hematoma (IMH), and penetrating aortic ulcer (PAU) from a population-based approach.

METHODS

Retrospective review of an incident cohort of AD, IMH, and PAU patients in Olmsted County, Minnesota from 1995 to 2015. Primary end point was aortic death. Secondary end points were subsequent aortic events (aortic intervention, new dissection, or rupture not present at presentation) and first-time diagnosis of an aortic aneurysm. Outcomes were compared with randomly selected population referents matched for age and sex in a 3:1 ratio using Cox proportional hazards regression adjusting for comorbidities.

RESULTS

Among 133 patients (77 AD, 21 IMH, and 35 PAU), 57% were males, and mean age was 71.8 years (standard deviation, 14). Median follow-up was 10 years. Of 73 deaths among AD/IMH/PAU patients, 23 (32%) were aortic-related. Estimated freedom from aortic death was 84%, 80%, and 77% at 5, 10, and 15 years. There were no aortic deaths among population referents (adjusted hazard ratio [HR] for aortic death in AD/IMH/PAU, 184.7; 95% confidence interval [95% CI], 10.3-3,299.2; P < 0.001). Fifty (38%) AD/IMH/PAU patients had a subsequent aortic event (aortic intervention, new dissection, or rupture), whereas there were 8 (2%) aortic events among population referents (all elective aneurysm repairs; adjusted HR for any aortic event and aortic intervention in AD/IMH/PAU patients, 33.3; 95% CI, 15.3-72.0; P < 0.001 and 31.5; 95% CI, 14.5-68.4; P < 0.001, respectively). After excluding aortic events/interventions ≤14 days of diagnosis, AD/IMH/PAU patients remained at increased risk of any aortic event (adjusted HR, 10.8; 95% CI, 3.9-29.8; P < 0.001) and aortic intervention (adjusted HR, 9.6; 95% CI, 3.4-26.8; P < 0.001). Among those subjects with available follow-up imaging, the risk of first-time diagnosis of aortic aneurysm was significantly increased for AD/IMH/PAU patients when compared with population referents (adjusted HR, 10.9; 95% CI, 5.4-21.7; P < 0.001 and 8.3; 95% CI, 4.1-16.7; P < 0.001 for thoracic and abdominal aneurysms, respectively) and remained increased when excluding aneurysms that formed within 14 days of AD/IMH/PAU (adjusted HR, 6.2; 95% CI, 1.8-21.1; P = 0.004 and 2.8; 95% CI, 1.0-7.6; P = 0.040 for thoracic and abdominal aneurysms, respectively).

CONCLUSIONS

AD/IMH/PAU patients have a substantial risk of aortic death, any aortic event, aortic intervention, and first-time diagnosis of aortic aneurysm that persists even when the acute phase (≤14 days after diagnosis) is uncomplicated. Advances in postdiagnosis treatment are necessary to improve the prognosis in these patients.

Low correlation between biometric parameters, cardiovascular risk factors and aortic dimensions by computed tomography coronary angiography

To analyze the relationship between aortic measures and biometric parameters in a large cohort of consecutive patients undergoing computed tomography coronary angiography.1170 patients (717 men/453 women) performing computed tomography coronary angiography for coronary evaluation were retrospectively evaluated. Aortic diameters and areas were measured at reproducible anatomic landmarks, perpendicular to the axis of vessel, at the level of the aortic root (AoR), the sinotubular junction (STJ), and the tubular ascending aorta (TAo). Biometric parameters and cardiovascular risk factors were recorded.The average values of AoR, STJ, and TAo were 35.63 ± 5.00 mm, 30.56 ± 4.82 mm, 35.07 ± 5.84 mm. Hypertension was significantly associated with aortic dimensions.Aortic measures were significantly different between men and women (37.56 ± 4.77 mm vs 32.58 ± 3.68 mm for AoR, 31.88 ± 4.84 mm vs 28.47 ± 3.98 mm for STJ and 35.93 ± 5.86 mm vs 33.70 ± 5.54 mm for TAo) (P < .001) and linearly increased with age. Low Spearman correlation coefficients were found and the correlation of TAo diameters with age displayed the highest values (ρ = 0.372 for male and ρ = 0.373 for female, P < .001). Multiple linear regression analysis models were compared by R. The best model used body surface area (BSA) and age as independent variables and TAo diameter as dependent variable (R = 0.29 for AoR; R = 0.21 for STJ, and R = 0.20 for TAo).In conclusion, in our population low correlation between aortic dimensions and biometric parameters highlights the difficulty of identifying normal ranges, as well as issues related to normalization using conventional biometric parameters.

Morphometry of the Brachiocephalic Artery: A Cadaveric Anatomical Study

Introduction

The brachiocephalic artery (BCA) is the largest branch that arises from the aortic arch, which varies in length. The present study focuses on BCA length and its probable correlation with height and torso length.

Methods

The BCA length (from the artery’s origin to the arcus aortae), the length of the torso, and height were measured in 76 embalmed adult human cadavers of Caucasian (Hellenic) origin.

Results

A total of 74 arteries were measured (36 females and 38 males). The mean length was found to be 3.82 cm (SD=±0.947, SE=0.110). In male cadavers, the mean BCA length was 3.94 cm (SD=±0.980, SE=0.159) and in females, it was found to be 3.69 cm (SD=±0.905, SE=0.151). No statistically significant difference was found (p=0.248, p>0.05) The mean torso length was 62.27 cm (SD=±4.325, SE=0.496) and the mean height was 155.3 cm (SD=±10.124, SE=1.161). The BCA length was correlated with body height and torso length in both sexes. A statistically significant correlation was found only between BCA length and body height in male cadavers (r=0.267, p=0.021).

Conclusion

The morphometric characteristics of the BCA are of great importance in a number of surgical procedures, such as stenting and catheterization in cases of aneurysms. One statistically significant correlation was observed in our study, which could be considered an important finding, as it could lead to the plausible assumption that greater height leads to the formation of larger arteries.

Intracranial Arterial Tortuosity in Marfan Syndrome and Loeys-Dietz Syndrome: Tortuosity Index Evaluation Is Useful in the Differential Diagnosis

BACKGROUND AND PURPOSE

The association of arterial tortuosity and connective tissue diseases is widely reported in the literature, but only a few studies were based on a quantitative evaluation of this arterial phenotype, and none of the latter examined the intracranial vasculature. The aim of this study was to evaluate the degree of intracranial arterial tortuosity in patients with Marfan syndrome and those with Loeys-Dietz syndrome, and to assess its usefulness in the differential diagnosis.

MATERIALS AND METHODS

We performed a retrospective analysis of 68 patients with genetically confirmed Marfan syndrome (n = 36) or Loeys-Dietz syndrome (n = 32), who underwent at least 1 MRA of the brain at our institution. Fifty-two controls were randomly selected among patients who presented with headache and without any known comorbidity. Tortuosity indexes of 4 intracranial arterial segments were measured on a 3D volume-rendered angiogram by using the following formula: [Formula: see text].

RESULTS

Both Marfan syndrome and Loeys-Dietz syndrome showed a significantly higher tortuosity index compared with controls in all examined vessels. The tortuosity index of the vertebrobasilar system showed an excellent interrater reliability (intraclass correlation coefficient, 0.99) and was the strongest independent predictor of Loeys-Dietz syndrome in patients with connective tissue disease (P = .002), with a 97% specificity for this pathology when its value was > 60.

CONCLUSIONS

The tortuosity index of intracranial arteries is an easily calculated and highly reproducible measure, which shows a high specificity for Marfan syndrome and Loeys-Dietz syndrome and may be useful in differentiating these 2 entities.

Biomechanical Assessment of Bicuspid Aortic Valve Phenotypes: A Fluid-Structure Interaction Modelling Approach

PURPOSE

Bicuspid aortic valve (BAV) is a congenital heart malformation with phenotypic heterogeneity. There is no prior computational study that assesses the haemodynamic and valve mechanics associated with BAV type 2 against a healthy tricuspid aortic valve (TAV) and other BAV categories.

METHODS

A proof-of-concept study incorporating three-dimensional fluid-structure interaction (FSI) models with idealised geometries (one TAV and six BAVs, namely type 0 with lateral and anterior-posterior orientations, type 1 with R-L, N-R and N-L leaflet fusion and type 2) has been developed. Transient physiological boundary conditions have been applied and simulations were run using an Arbitrary Lagrangian-Eulerian formulation.

RESULTS

Our results showed the presence of abnormal haemodynamics in the aorta and abnormal valve mechanics: type 0 BAVs yielded the best haemodynamical and mechanical outcomes, but cusp stress distribution varied with valve orifice orientation, which can be linked to different cusp calcification location onset; type 1 BAVs gave rise to similar haemodynamics and valve mechanics, regardless of raphe position, but this position altered the location of abnormal haemodynamic features; finally, type 2 BAV constricted the majority of blood flow, exhibiting the most damaging haemodynamic and mechanical repercussions when compared to other BAV phenotypes.

CONCLUSION

The findings of this proof-of-concept work suggest that there are specific differences across haemodynamics and valve mechanics associated with BAV phenotypes, which may be critical to subsequent processes associated with their pathophysiology processes.

Imaging Thoracic Aortic Aneurysm

High-quality aortic imaging plays a central role in the management of patients with thoracic aortic aneurysm. Computed tomography angiography and magnetic resonance angiography are the most commonly used techniques for thoracic aortic aneurysm diagnosis and imaging surveillance, with each having unique strengths and limitations that should be weighed when deciding patient-specific applications. To ensure optimal patient care, imagers must be familiar with potential sources of artifact and measurement error, and dedicate effort to ensure high-quality and reproducible aortic measurements are generated. This review summarizes the imaging evaluation and underlying pathology relevant to the diagnosis of thoracic aortic aneurysm.

Sinus of Valsalva Aneurysms: A State-of-the-Art Imaging Review

Cardiovascular imaging has an important role in the assessment and management of aortic root and thoracic aorta ectasia and aneurysms. Sinus of Valsalva aneurysms are rare entities. Unique complications associated with sinus of Valsalva aneurysms make them different from traditional aortic root aneurysms. Established guidelines on the diagnosis and management of sinus of Valsalva aneurysms are lacking. This article reviews the applications of multimodality cardiovascular imaging (echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging) for the dedicated assessment and imaging-guided management of sinus of Valsalva aneurysms.

Aortic volume determines global end-diastolic volume measured by transpulmonary thermodilution

Background

Global end-diastolic volume (GEDV) measured by transpulmonary thermodilution is regarded as indicator of cardiac preload. A bolus of cold saline injected in a central vein travels through the heart and lung, but also the aorta until detection in a femoral artery. While it is well accepted that injection in the inferior vena cava results in higher values, the impact of the aortic volume on GEDV is unknown. In this study, we hypothesized that a larger aortic volume directly translates to a numerically higher GEDV measurement.

Methods

We retrospectively analyzed data from 88 critically ill patients with thermodilution monitoring and who did require a contrast-enhanced thoraco-abdominal computed tomography scan. Aortic volumes derived from imaging were compared with GEDV measurements in temporal proximity.

Results

Median aortic volume was 194 ml (interquartile range 147 to 249 ml). Per milliliter increase of the aortic volume, we found a GEDV increase by 3.0 ml (95% CI 2.0 to 4.1 ml, p < 0.001). In case a femoral central venous line was used for saline bolus injection, GEDV raised additionally by 2.1 ml (95% CI 0.5 to 3.7 ml, p = 0.01) per ml volume of the vena cava inferior. Aortic volume explained 59.3% of the variance of thermodilution-derived GEDV. When aortic volume was included in multivariate regression, GEDV variance was unaffected by sex, age, body height, and weight.

Conclusions

Our results suggest that the aortic volume is a substantial confounding variable for GEDV measurements performed with transpulmonary thermodilution. As the aorta is anatomically located after the heart, GEDV should not be considered to reflect cardiac preload. Guiding volume management by raw or indexed reference ranges of GEDV may be misleading.

Retrograde aortic access during ventricular tachycardia ablation: Indications, techniques, and challenges

The retrograde aortic (RA) route is a widely used access route for mapping and ablation of ventricular tachycardias (VT) arising from the left ventricular endocardium. With the expanding role of VT ablation in patients with significant comorbidity, the choice between the RA and transseptal access routes is an increasingly important consideration. An individualized decision based on the location of the arrhythmogenic substrate, vascular anatomy, aortic valve morphology, and operator experience is necessary when deciding on the optimal access route. Among patients with challenging vascular anatomy, growing experience from structural interventions such as transcatheter aortic valve replacements and peripheral vascular interventions has provided valuable insights into techniques for safe retrograde access. The present review focuses on patient selection for RA access, potential complications associated with the technique, and optimal approaches for access in patients with challenging vascular or aortic valve anatomy.

Is there any association between aortic root rotation angle and aortic dissection?

Introduction

Thoracic aortic dissection is a probable fatal condition that requires early diagnosis and management. The underlying etiology of this disorder is an important issue that has not been completely responded yet. In the current study, the association between aortic root rotation and ascending aortic dissection has been assessed.

Methods

This is a non-randomized retrospective case-control study conducted on twenty-five cases referring with ascending aortic dissection and seventy-five controls that underwent computed tomography (CT) angiography for reasons other than aortic dissection. Aortic root rotation angle and aortic diameter for both cases and controls were measured and then compared.

Results

There was no significant difference regarding age and gender distribution (P value = 0.22 and 0.38 respectively) between patients in case and control groups. The mean values of aortic root rotation angle and aortic diameter in cases were 22.5 ± 10.5° and 43.1 ± 12.5 mm versus 15.7 ± 10.7° and 30.7 ± 5.3 mm in controls (P value = 0.007 and 0.001 respectively). Direct relation was found between aortic root rotation angle and aortic diameter (P value = 0.007, r = 0.276). Mean of aortic root rotation angle was significantly higher in females (P value = 0.02). No association between cases' age with either aortic root rotation angle or aortic diameter was found (P value = 0.33, r = 0.098, and P value = 0.085, r = 0.173 respectively).

Conclusion

Based on the findings of the current study, aortic root rotation angle was independently in direct association with thoracic aortic dissection. In addition, females had higher aortic root rotation angles.

Testing the Translational Power of the Zebrafish: An Interspecies Analysis of Responses to Cardiovascular Drugs

The zebrafish is rapidly emerging as a promising alternative in vivo model for the detection of drug-induced cardiovascular effects. Despite its increasing popularity, the ability of this model to inform the drug development process is often limited by the uncertainties around the quantitative relevance of zebrafish responses compared with nonclinical mammalian species and ultimately humans. In this test of concept study, we provide a comparative quantitative analysis of the in vivo cardiovascular responses of zebrafish, rat, dog, and human to three model compounds (propranolol, losartan, and captopril), which act as modulators of two key systems (beta-adrenergic and renin–angiotensin systems) involved in the regulation of cardiovascular functions. We used in vivo imaging techniques to generate novel experimental data of drug-mediated cardiovascular effects in zebrafish larvae. These data were combined with a database of interspecies mammalian responses (i.e., heart rate, blood flow, vessel diameter, and stroke volume) extracted from the literature to perform a meta-analysis of effect size and direction across multiple species. In spite of the high heterogeneity of study design parameters, our analysis highlighted that zebrafish and human responses were largely comparable in >80% of drug/endpoint combinations. However, it also revealed a high intraspecies variability, which, in some cases, prevented a conclusive interpretation of the drug-induced effect. Despite the shortcomings of our study, the meta-analysis approach, combined with a suitable data visualization strategy, enabled us to observe patterns of response that would likely remain undetected with more traditional methods of qualitative comparative analysis. We propose that expanding this approach to larger datasets encompassing multiple drugs and modes of action would enable a rigorous and systematic assessment of the applicability domain of the zebrafish from both a mechanistic and phenotypic standpoint. This will increase the confidence in its application for the early detection of adverse drug reactions in any major organ system.

Predictive imaging for thoracic aortic dissection and rupture: moving beyond diameters

Abstract

Acute aortic syndromes comprise a group of potentially fatal conditions that result from weakening of the aortic vessel wall. Pre-emptive surgical intervention is currently reserved for patients with severe aortic dilatation, although abundant evidence describes the occurrence of dissection and rupture in aortas with diameters below surgical thresholds. Modern imaging techniques (such as hybrid PET-CT and 4D flow MRI) afford the non-invasive assessment of anatomic, hemodynamic, and molecular features of the aorta, and may provide for a more accurate selection of patients who will benefit from preventative surgical intervention. In the current review, we summarize evidence and considerations regarding predictive aortic imaging and highlight evolving imaging modalities that have shown promise to improve risk assessment for the occurrence of dissection and rupture.

Key Points

• Guidelines for the preventative management of aortic disease depend on maximal vessel diameters, while these have shown to be poor predictors for the occurrence of catastrophic acute aortic events.

• Evolving imaging modalities (such as 4D flow MRI and hybrid PET-CT) afford a more comprehensive insight into anatomic, hemodynamic, and molecular features of the aorta and have shown promise to detect vessel wall instability at an early stage.