Ascending Thoracic Aorta Research Articles

Significance of Dynamic Axial Stretching on Estimating Biomechanical Behavior and Properties of the Human Ascending Aorta

Contrary to most vessels, the ascending thoracic aorta (ATA) not only distends but also elongates in the axial direction. The purpose of this study is to investigate the biomechanical behavior of the ascending thoracic aorta (ATA) in response to dynamic axial stretching during the cardiac cycle. In addition, the implications of neglecting this dynamic axial stretching when estimating the constitutive model parameters of the ATA are investigated. The investigations were performed through in silico simulations by assuming a Gasser–Ogden–Holzapfel (GOH) constitutive model representative of ATA tissue material. The GOH model parameters were obtained from biaxial tests performed on four human ATA tissues in a previous study. Pressure–diameter curves were simulated as synthetic data to assess the effect of neglecting dynamic axial stretching on estimating constitutive model parameters. Our findings reveal a significant increase in axial stress (~ 16%) and stored strain energy (~ 18%) in the vessel when dynamic axial stretching is considered, as opposed to assuming a fixed axial stretch. All but one artery showed increased volume compliance while considering a dynamic axial stretching condition. Furthermore, we observe a notable difference in the estimated constitutive model parameters when dynamic axial stretching of the ATA is neglected, compared to the ground truth model parameters. These results underscore the critical importance of accounting for axial deformations when conducting in vivo biomechanical characterization of the ascending thoracic aorta.

Mapping the unicellular transcriptome of the ascending thoracic aorta to changes in mechanosensing and mechanoadaptation during aging.

Aortic stiffening is an inevitable manifestation of chronological aging, yet the mechano-molecular programs that orchestrate region- and layer-specific adaptations along the length and through the wall of the aorta are incompletely defined. Here, we show that the decline in passive cyclic distensibility is more pronounced in the ascending thoracic aorta (ATA) compared to distal segments of the aorta and that collagen content increases in both the medial and adventitial compartments of the ATA during aging. The single-cell RNA sequencing of aged ATA tissues reveals altered cellular senescence, remodeling, and inflammatory responses accompanied by enrichment of T-lymphocytes and rarefaction of vascular smooth muscle cells, compared to young samples. T lymphocyte clusters accumulate in the adventitia, while the activation of mechanosensitive Piezo-1 enhances vasoconstriction and contributes to the overall functional decline of ATA tissues. These results portray the immuno-mechanical aging of the ATA as a process that culminates in a stiffer conduit permissive to the accrual of multi-gerogenic signals priming to disease development.

Vascular Remodeling During Late-Gestation Pregnancy: An In-Vitro Assessment of the Murine Ascending Thoracic Aorta.

Maternal mortality due to cardiovascular disease is a rising concern in the U.S. Pregnancy triggers changes in the circulatory system, potentially influencing the structure of the central vasculature. Evidence suggests a link between a woman's pregnancy history and future cardiovascular health, but our understanding remains limited. To fill this gap, we examined the passive mechanics of the murine ascending thoracic aorta during late gestation. By performing biaxial mechanical testing on the ascending aorta, we were able to characterize the mechanical properties of both control and late-gestation tissues. By examining mechanical, structural, and geometric properties, we confirmed that remodeling of the aortic wall occurred. Morphological and mechanical properties of the tissue indicated an outward expansion of the tissue, as reflected in changes in wall thickness (∼12% increase) and luminal diameter (∼6% increase) at its physiologically loaded state in the pregnant group. With these geometric adaptations and despite increased hemodynamic loads, pregnancy did not induce significant changes in the tensile wall stress at the similar physiological pressure levels of the pregnant and control tissues. The alterations also included reduced intrinsic stiffness in the circumferential direction (∼18%) and reduced structural stiffness (∼26%) in the pregnant group. The observed vascular remodeling maintained the elastic stored energy of the aortic wall under systolic loads, indicating preservation of vascular function. Data from our study of pregnancy-related vascular remodeling will provide valuable insights for future investigations of maternal cardiovascular health.

Evaluation of Pulmonary Hypertension in Dogs with Heartworm Disease Using the Computed Tomographic Pulmonary Trunk to Aorta Diameter Ratio.

Simple SummaryPulmonary hypertension (PH) is a consequence of proliferative pulmonary endoarteritis caused by the parasite Dirofilaria immitis (heartworm). To date, the diagnosis is carried out through echocardiographic determinations, with the right pulmonary artery distensibility (RPAD) index being the gold standard for diagnosis of PH caused by heartworm. Given the high importance and frequency of PH in dogs, the study of the pulmonary trunk to aorta ratio (PT:Ao) determined by computed tomography (CT) was proposed to assess its usefulness in the diagnosis of PH, compared to the gold standard method. The results show that the PT:Ao ratio was reliable for detecting and staging the severity of moderate to severe PH in dogs with heartworm.Dirofilaria immitis causes proliferative pulmonary endoarteritis that leads to the appearance of chronic precapillary pulmonary hypertension (PH) in dogs. Pulmonary trunk to aorta ratio (PT:Ao ratio) obtained by computed tomography (CT) was studied and the quantitative measure of the diameters of the pulmonary trunk (PT), the descending thoracic aorta (DAo) and ascending thoracic aorta (AAo) were evaluated for the determination of the presence of moderate to severe PH in 59 dogs. The diagnosis of PH was echocardiographically determined, based on the determination of the right pulmonary artery distensibility (RPAD) index (<29.5%), and compared with other parameters for estimating PH. The results showed a very high concordance: 0.976 (p-value 0.000) between the two CT methods (PT:DAo and PT:AAo) with an excellent intraclass correlation coefficient > 0.95. Moreover, cut-off values of ≥1.111 for PT:DAo, and ≥1.057 for PT:AAo were determined for dogs with an RPAD index < 29.5%, which suggests a cut-off value between healthy dogs and the presence of PH. As has been previously published, The PT:Ao ratios did not determine the presence of mild PH, so the measurements cannot be considered useful for the early diagnosis of PH in dogs with heartworm.

Is location a significant parameter in the layer dependent dissection properties of the aorta?

Proper characterisation of biological tissue is key to understanding the effect of the biomechanical environment in the physiology and pathology of the cardiovascular system. Aortic dissection in particular is a prevalent and sometimes fatal disease that still lacks a complete comprehension of its progression. Its development and outcome, however, depend on the location in the vessel. Dissection properties of arteries are frequently studied via delamination tests, such as the T-peel test and the mixed-mode peel test. So far, a study that performs both tests throughout different locations of the aorta, as well as dissecting several interfaces, is missing. This makes it difficult to extract conclusions in terms of vessel heterogeneity, as a standardised experimental procedure cannot be assured for different studies in literature. Therefore, both dissection tests have been here performed on healthy porcine aortas, dissecting three interfaces of the vessels, i.e., the intima-media, the media-adventitia and the media within itself, considering different locations of the aorta, the ascending thoracic aorta (ATA), the descending thoracic aorta and the infrarenal abdominal aorta (IAA). Significant differences were found for both, layers and location. In particular, dissection forces in the ATA were the highest and the separation of the intima-media interface required significantly the lowest force. Moreover, dissection in the longitudinal direction of the vessel generally required more force than in the circumferential one. These results emphasise the need to characterise aortic tissue considering the specific location and dissected layer of the vessel.

Bentall surgery and total arch repair with debranching of supra-aortic vessels: a case report

BackgroundThe surgical approach to pathologies of the Ascending Thoracic Aorta (ATA) that compromise aortic root and the aortic arch is currently one of the most complex interventions in the spectrum of cardiac surgery, where circulatory arrest with cerebral perfusion plays an important role for Success postoperative and patient survival.Case presentationWe present the case of a 57-year-old patient with the only history of arterial hypertension and an ATA Aneurysm that compromised segment of the aortic root up to segment 2 of the aortic arch. A successful Bentall surgery was performed, debranching supra-aortic vessels with Total Circulatory Arrest with Deep Hypothermic Cerebral Perfusion-Antegrade Bilateral.ConclusionsWith the advent of new anesthetic and neuroprotection techniques, perioperative imaging protocols, advanced hemodynamic monitoring, and invaluable advances in perfusion and Extracorporeal Circulation with circulatory arrest, they have made this surgical challenge a valuable tool for today’s cardiovascular surgeon.

About prestretch in homogenized constrained mixture models simulating growth and remodeling in patient-specific aortic geometries

Evolution of mechanical and structural properties in the Ascending Thoracic Aorta (ATA) is the results of complex mechanobiological processes. In this work, we address some numerical challenges in order to elaborate computational models of these processes. For that, we extend the state of the art of homogenized constrained mixture (hCM) models. In these models, prestretches are assigned to the mixed constituents in order to ensure local mechanical equilibrium macroscopically, and to maintain a homeostatic level of tension in collagen fibers microscopically. Although the initial prestretches were assumed as homogeneous in idealized straight tubes, more elaborate prestretch distributions need to be considered for curved geometrical models such as patient-specific ATA. Therefore, we introduce prestretches having a three-dimensional gradient across the ATA geometry in the homeostatic reference state. We test different schemes with the objective to ensure stable growth and remodeling (G&R) simulations on patient-specific curved vessels. In these simulations, aneurysm progression is triggered by tissue changes in the constituents such as mass degradation of intramural elastin. The results show that the initial prestretches are not only critical for the stability of numerical simulations, but they also affect the G&R response. Eventually, we submit that initial conditions required for G&R simulations need to be identified regionally for ensuring realistic patient-specific predictions of aneurysm progression.

Post-operative computed tomography imaging evaluation of ascending aorta surgery.

Ascending thoracic aorta disease is often a life-threatening condition. Aortic aneurysm and aortic dissection are the most frequent ascending aorta diseases requiring surgical intervention. Surgical repair techniques of the ascending aorta are various; they include reconstruction of the ascending aorta by using a graft with or without a prosthetic valve, reconstruction with a composite artificial graft or using a biological graft, and reconstruction of the ascending aorta with a composite graft preserving the native valve and arch repair. The radiologist plays a key role in the identification of post-operative complications; differentiation from normal postoperative findings is fundamental. Our aim is to discuss the main diseases affecting the ascending aorta requiring surgery and the different techniques used to treat them. We also discuss the normal computed tomography (CT) imaging findings and after-surgery complications.

Natural history of the enlarged ascending thoracic aorta: an observational long term study

Abstract To assess the long-term outcome of patients with an enlarged ascending thoracic aorta (ATA), a retrospective study was performed. Methods Inclusion criteria: ATA diameter of 38 mm or more by ETT (813 consecutive cases). Inclusion period: 1.1.2003–31.12.2016. Results At baseline, the mean diameter of the ATA was 42±3 mm, the mean Z-score was 2.7±0.8. In the subgroup of patients with 2 ETT examinations (and no surgical cure of the ATA), the mean diameter was 41.9±4.8 mm, the mean Z-score 2.4±1.1 after a mean follow-up of 6 years. During the follow-up, 52 patients had an intervention on the ATA, 26 patients were operated within the first 3 months after the diagnostic echocardiogram. 26 patients were operated during FU. In the 791 remaining patients (without early intervention), the event rate (death, intervention on the ATA) were assessed by the competing risk model. In the group of patients with a baseline ATA diameter of less than 41 mm (Group A: n=254), the cumulative incidence of death at 5 and 10 y was 34% and 61%; in the group of patients with an ATA diameter of 41–42 mm (Group B: n=238) the incidence was 34% and 61% respectively, in the group of patients with an ATA diameter of 43–44 mm (Group C: n=147), the incidence was 32% and 58%, in the group of patients with a diameter of 45 and more (Group D: n=150), the incidence was 31.1% and 61% (NS). The cumulative incidence of surgical interventions on the ATA at 5 and 10 years was 0.4% and 1% in group A, 1.3 and 1.8% in group B, 0.7 and 1.4% in group C and 9.8 and 12.9% in group D (p&amp;lt;0.05). Similar results were observed in patients according to the Z-scores. In the group of patients (221) with a Z-score &amp;gt;3, the incidence of intervention at 5 and 10 y was respectively 7.6% and 10.7% (p=0.01). Conclusions – The mean diameter of the enlarged ATA remained nearly unchanged over a period of 6 years. – No impact of the enlarged ATA on survival was observed. – Only patients with an ATA diameter of 45 mm and more (or a Z-score of 3 and more) needed an intervention on the ATA at a rate of ± 10% at 10 y after the initial echocardiographic diagnosis. Funding Acknowledgement Type of funding source: None

Endovascular Repair of Blunt Thoracic Aortic Trauma is Associated With Increased Left Ventricular Mass, Hypertension, and Off-target Aortic Remodeling.

Aortic elasticity creates a cushion that protects the heart from pressure injury, and a recoil that helps perfuse the coronary arteries. TEVAR has become first-line therapy for many aortic pathologies including trauma, but stent-grafts stiffen the aorta and likely increase LV afterload. Test the hypothesis that trauma TEVAR is associated with LV mass increase and adverse off-target aortic remodeling. Computed Tomography Angiography (CTA) scans of 20 trauma TEVAR patients (17 M/3 F) at baseline [age 34.9 ± 18.5 (11.4-71.5) years] and 5.1 ± 3.1 (1.1-12.3) years after repair were used to measure changes in LV mass, LV mass index, and diameters and lengths of the ascending thoracic aorta (ATA). Measurements were compared with similarly-aged control patients without aortic repair (21 M/21 F) evaluated at similar follow-ups. LV mass and LV mass index of TEVAR patients increased from 138.5 ± 39.6 g and 72.35 ± 15.17 g/m2 to 173.5 ± 50.1 g and 85.48 ± 18.34 g/m2 at the rate of 10.03 ± 12.79 g/yr and 6.25 ± 10.28 g/m2/yr, whereas in control patients LV characteristics did not change. ATA diameters of TEVAR patients increased at a rate of 0.60 ± 0.80 mm/yr, which was 2.4-fold faster than in controls. ATA length in both TEVAR and control patients increased at 0.58 mm/yr. Half of TEVAR patients had hypertension at follow-up compared to only 5% at baseline. TEVAR is associated with LV mass increase, development of hypertension, and accelerated expansile remodeling of the ascending aorta. Although younger trauma patients may adapt to these effects, these changes may be even more important in older patients with other aortic pathologies and diminished baseline cardiac function.

Correlation between wall shear stress and wall rupture properties in ascending thoracic aortic aneurysms

Ascending thoracic aorta aneurysm (ATAA) is the 19th common cause of human deaths. Despite important recent progress to better understand the pathogenesis and the development of the disease, the ro...

Natural history of the enlarged ascending thoracic aorta: An observational long-term study

To assess the long-term outcome of patients with an enlarged ascending thoracic aorta (ATA), a retrospective study was performed. Inclusion criteria: ATA diameter of 38 mm or more by ETT (813 consecutive cases). Inclusion period: 01.1.2003–31.12.2016. At baseline, the mean diameter of the ATA was 42 ± 3 mm, the mean Z-score was 2.7 ± 0.8. Six years later, the mean diameter was 41.9 ± 4.8 mm, the mean Z-score 2.4 ± 1.1. During the follow-up, 52 patients had an intervention on the ATA, 22 patients were operated within the first 3 months after the diagnostic echocardiogram. In the 791 remaining patients (without early intervention), the event rate (death, intervention on the ATA) was assessed by the competing risk model. In the group of patients with a baseline ATA diameter of less than 41 mm (Group A: n = 254), the cumulative incidence of death at 5 and 10 y was 34% and 61%; in the group of patients with an ATA diameter of 41–42 mm (Group B: n = 238) the incidence was 34% and 61% respectively, in the group of patients with an ATA diameter of 43-44 mm (Group C: n = 147), the incidence was 32% and 58%, in the group of patients with a diameter of 45 and more (Group D: n = 150), the incidence was 31.1% and 61% (NS). The cumulative incidence of intervention at 5 and 10 years was 0.4% and 1% in group A, 1.3 and 1.8% in group B, 0.7 and 1.4% in group C and 9.8 and 12.9% in group D ( P < 0.05). Similar results were observed in patients according to the Z-scores. In the group of patients (221) with a Z-score > 3, the incidence of intervention at 5 and 10 y was respectively 7.6% and 10.7% ( P = 0.01). The diameter of the enlarged ATA remained nearly unchanged over a period of 6 years. No impact of the enlarged ATA on survival was observed. Only patients with an ATA diameter of 45 mm and more (or a Z-score of 3 and more) needed an intervention at a rate of ±10% at 10 y after the initial echocardiographic diagnosis.

Quantification of Respiratory Movement of the Aorta and Side Branches

Purpose: To assess and quantify the magnitude and direction of respiratory movement of the aorta and origins of its side branches. Methods: A quantitative 3-dimensional (3D) subtraction analysis of computed tomography (CT) scans during inspiration and expiration was performed to determine the respiratory geometric movements of the aorta and side branches in 60 patients. During breath-hold expiration and inspiration, 1-mm-thick CT slices of the aorta were acquired in unenhanced and contrast-enhanced scans. The datasets were compared using dedicated multiplanar reformation image subtraction software to determine the change in position of relevant anatomic sections, including the ascending thoracic aorta (AA), the origins of the brachiocephalic artery (BA) and left subclavian artery (LSA), the descending thoracic aorta (DTA) at the level of the tenth thoracic vertebra, as well as the origins of the celiac trunk, superior mesenteric artery, and the renal arteries. Results: Complex movement was visible during inspiration; the regions of interest in the thoracic aorta and side branches moved in the anterior, medial, and caudal directions compared with the expiration state. Mean 3D movement vectors (± standard deviation) were 8.9±3.6 mm (AA), 12.0±4.1 mm (BA), 11.1±3.9 mm (LSA), and 4.9±2.5 mm (DTA). Abdominal side branches moved in the caudal direction 1.3±1.1 mm. There was significantly less movement in the DTA compared to AA (p<0.001). The correlation coefficient between the extent of LSA movement and thoracic excursion was 0.78. Conclusion: The aorta and side branches undergo considerable respiratory movement. The results from this study provide an important contribution to understanding aortic dynamics.

Effect of aneurysm on biomechanical properties of “radially-oriented” collagen fibers in human ascending thoracic aortic media

We recently reported a mechanistic model to link micro-architectural information to the delamination strength (Sd) of human ascending thoracic aorta (ATA). That analysis demonstrated that the number density (N) and failure energy (Uf) of the radially-oriented collagen fibers contribute to the Sd of both aneurysmal (ATAA) and non-aneurysmal (CTRL-ATA) aortic tissue. Among the set of ATAA samples, we studied specimens from patients displaying bicuspid (BAV) and tricuspid aortic valve (TAV) morphologic phenotypes. Results from our prior work were based on the assumption that the Uf was independent of dissection direction. In the current study, we excluded that assumption and hypothesized that Uf correlates with the Sd of ATAA. To test the hypothesis, we used previously-reported experimentally-determined Sd measurements and N of radially-oriented collagen fibers as input in our validated mechanistic model to calculate Uf for BAV-ATAA, TAV-ATAA and CTRL-ATA tissue specimens. The results of our analysis revealed that Uf is significantly lower for both BAV-ATAA and TAV-ATAA compared to CTRL-ATA cases, and does not differ between BAV-ATAA and TAV-ATAA. Furthermore, we found that Uf is consistent between circumferential-radial and longitudinal-radial planes in either of BAV-ATAA, TAV-ATAA or CTRL-ATA specimens. These findings employ a novel mechanistic model to increase our understanding of the putative interrelationship between biomechanical properties, extracellular matrix biology, and failure energy of aortic dissection.

Prefailure and Failure Mechanics of the Porcine Ascending Thoracic Aorta: Experiments and a Multiscale Model

Ascending thoracic aortic aneurysms (ATAA) have a high propensity for dissection, which occurs when the hemodynamic load exceeds the mechanical strength of the aortic media. Despite our recognition of this essential fact, the complex architecture of the media has made a predictive model of medial failure-even in the relatively simple case of the healthy vessel-difficult to achieve. As a first step towards a general model of ATAA failure, we characterized the mechanical behavior of healthy ascending thoracic aorta (ATA) media using uniaxial stretch-to-failure in both circumferential (n = 11) and axial (n = 11) orientations and equibiaxial extensions (n = 9). Both experiments demonstrated anisotropy, with higher tensile strength in the circumferential direction (2510 ± 439.3 kPa) compared to the axial direction (750 ± 102.6 kPa) for the uniaxial tests, and a ratio of 1.44 between the peak circumferential and axial loads in equibiaxial extension. Uniaxial tests for both orientations showed macroscopic tissue failure at a stretch of 1.9. A multiscale computational model, consisting of a realistically aligned interconnected fiber network in parallel with a neo-Hookean solid, was used to describe the data; failure was modeled at the fiber level, with an individual fiber failing when stretched beyond a critical threshold. The best-fit model results were within the 95% confidence intervals for uniaxial and biaxial experiments, including both prefailure and failure, and were consistent with properties of the components of the ATA media.

Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media

It was recently demonstrated by our group that the delamination strength of ascending thoracic aortic aneurysms (ATAA) was lower than that of control (CTRL, non-aneurysmal) ascending thoracic aorta (ATA), and the reduced strength was more pronounced among bicuspid (BAV) vs. tricuspid aortic valve (TAV) patients, suggesting a different risk of aortic dissection for BAV patients. We hypothesized that aortic valve morphologic phenotype predicts fiber micro-architectural anomalies in ATA. To test the hypothesis, we characterized the micro-architecture in the longitudinal-radial (Z-RAD) and circumferential-radial (Θ-RAD) planes of human ATA tissue that was artificially dissected medially. The outer and inner-media of CTRL-ATA, BAV-ATAA and TAV-ATAA were imaged using multi-photon microscopy in the Z-RAD and Θ-RAD planes to observe collagen and elastin. Micrographs were processed using an image-based tool to quantify several micro-architectural characteristics. In the outer-media of BAV-ATAA, elastin was more undulated and less aligned about the Θ-axis when compared with CTRL-ATA, which is consistent with increased tensile stretch at inflection point of Θ-strips of adventitial-medial half of BAV-ATAA (1.28) when compared with CTRL-ATA (1.13). With increasing age, collagen became more undulated about the Z-axis within the outer-media of TAV-ATAA, and elastin became more oriented in the Z-axis and collagen less radially-oriented within the inner-media of TAV-ATAA. This discrepancy in the micro-architecture with fibers in the inner layers being more stretched and with disrupted radially-oriented components than fibers in the outer layers may be associated with the development, progression and vascular remodeling in aneurysms arising in TAV patients.

Aortic Distensibility in Type 1 Diabetes

OBJECTIVETo evaluate the relationship between long-term glycemia, traditional cardiovascular disease (CVD) risk factors, and ascending aortic stiffness in type 1 diabetes.RESEARCH DESIGN AND METHODSEight hundred seventy-nine subjects in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study were evaluated. The stiffness/distensibility of the ascending thoracic aorta (AA) was measured with magnetic resonance imaging. Associations of AA distensibility and CVD risk factors, mean HbA1c, and cardiovascular complications including macroalbuminuria were assessed using multivariate linear regression models.RESULTSThe mean age of the subjects was 50 ± 7 years (47% women, mean diabetes duration of 28 years). Over 22 years of follow-up, 27% of participants had cardiovascular complications. After adjusting for gender and cohort, AA distensibility was lower with increasing age, mean systolic blood pressure, LDL, and HbA1c measured over an average of 22 years (−26.3% per 10 years, −11.0% per 10 mmHg SBP, −1.8% per 10 mg/dL of LDL, and −9.3% per unit mean HbA1c [%], respectively). Patients with macroalbuminuria had 25% lower AA distensibility compared with those without (P < 0.0001). Lower AA distensibility also was associated with greater ratio of left ventricular mass to volume (−3.4% per 0.1 g/mL; P < 0.0001).CONCLUSIONSOur findings indicate strong adverse effects of hypertension, chronic hyperglycemia and macroalbuminuria on AA stiffness in type 1 diabetes in the DCCT/EDIC cohort.

Determinants and normal values of ascending aortic diameter by age, gender, and race/ethnicity in the Multi‐Ethnic Study of Atherosclerosis (MESA)

To determine the normal size and wall thickness of the ascending thoracic aorta (AA) and its relationship with cardiovascular risk factors in a large population-based study. The mean AA luminal diameter was measured in 3573 Multi-Ethnic Study of Atherosclerosis (MESA) participants (age: 45-84 years), using gradient echo phase contrast cine MRI. Multiple linear regression models were used to evaluate the associations between risk factors and AA diameter. The median and upper normal limit (95th percentile) was defined in a "healthy" subgroup as well as AA wall thickness. The upper limits of body surface area indexed AA luminal diameter for age categories of 45-54, 55-64, 65-74, and 75-84 years are 21, 22, 22, and 28 mm/m(2) in women and 20, 21, 22, 23 mm/m(2) in men, respectively. The mean AA wall thickness was 2.8 mm. Age, gender, and body surface area were major determinants of AA luminal diameter (∼+1 mm/10 years; ∼+1.9 mm in men than women; ∼+1 mm/ 0.23 m(2) ; P < 0.001). The AA diameter in hypertensive subjects was +0.9 mm larger than in normotensives (P < 0.001). AA diameter increases gradually with aging for both genders among all race/ethnicities. The normal value of AA diameter is provided.

Distribution, Determinants, and Normal Reference Values of Thoracic and Abdominal Aortic Diameters by Computed Tomography (from the Framingham Heart Study)

Current screening and detection of asymptomatic aortic aneurysms is based largely on uniform cut-point diameters. The aims of this study were to define normal aortic diameters in asymptomatic men and women in a community-based cohort and to determine the association between aortic diameters and traditional risk factors for cardiovascular disease. Measurements of the diameters of the ascending thoracic aorta (AA), descending thoracic aorta (DTA), infrarenal abdominal aorta (IRA), and lower abdominal aorta (LAA) were acquired from 3,431 Framingham Heart Study (FHS) participants. Mean diameters were stratified by gender, age, and body surface area. Univariate associations with risk factor levels were examined, and multivariate linear regression analysis was used to assess the significance of covariate-adjusted relations with aortic diameters. For men, the average diameters were 34.1 mm for the AA, 25.8 mm for the DTA, 19.3 mm for the IRA, and 18.7mm for the LAA. For women, the average diameters were 31.9 mm for the AA, 23.1mm for the DTA, 16.7 mm for the IRA, and 16.0 mm for the LAA. The mean aortic diameters were strongly correlated (p <0.0001) with age and body surface area in age-adjusted analyses, and these relations remained significant in multivariate regression analyses. Positive associations of diastolic blood pressure with AA and DTA diameters in both genders and pack-years of cigarette smoking with DTA diameter in women and IRA diameter in men and women were observed. In conclusion, average diameters of the thoracic and abdominal aorta by computed tomography are larger in men compared with women, vary significantly with age and body surface area, and are associated with modifiable cardiovascular disease risk factors, including diastolic blood pressure and cigarette smoking.

Body-surface adjusted aortic reference diameters for improved identification of patients with thoracic aortic aneurysms: Results from the population-based Heinz Nixdorf Recall study

BackgroundEarly identification of patients at risk for thoracic aortic aneurysm (TAA) has the potential of improving prognosis. So far, however, “normal” aortic dimensions are not well defined, rendering identification of patients with enlarged aortas difficult. In the present study we aimed to (1) establish age- and gender-specific distribution of thoracic aortic diameters and (2) to determine the prevalence of asymptomatic TAA in a population-based European cohort. MethodsDiameters of ascending thoracic aorta (ATA) and descending thoracic aorta (DTA) were measured from electron beam computed tomography (EBCT) scans of 4129 participants aged 45 to 75years from the Heinz Nixdorf Recall study. Age- and gender-specific percentiles were calculated for body-surface adjusted aortic diameters. Multivariable linear regression was used to evaluate the association between aortic diameters and cardiovascular risk factors including age, gender and body-surface area (BSA). ResultsAortic diameters were generally greater in the ATA than in the DTA, and were greater in men than in women (ATA: 3.71±0.4cm vs. 3.45±0.4cm, p<0.0001; DTA: 2.82±0.3cm vs. 2.54±0.3cm, p<0.0001). Age, male gender, blood pressure and body-surface area were independently associated with aortic diameters in both ATA and DTA. Based on our measurements age- and gender-specific percentiles for indexed ATA and DTA diameters were computed. Aneurysms≥5cm were found in 12 (0.34%) out of the total of 4129 subjects. ConclusionSince BSA was independently associated with increasing aortic diameters, correction of aortic diameters for BSA may be more helpful in order to reliably identify patients at risk for aneurysm formation. Based on the normal distribution of body-surface adjusted thoracic aortic diameters displayed in age- and gender-specific percentiles we suggest a cut-off point for aneurismal aortic diameter at the 95th percentile.