Aortic Root Measurement by Cardiovascular Magnetic Resonance

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.

Evaluating a Novel AI Tool for Automated Measurement of the Aortic Root and Valve in Cardiac Magnetic Resonance Imaging

Objective Evaluating an artificial intelligence (AI) tool (AIATELLA, version 1.0; AIATELLA Oy, Helsinki, Finland) in interpreting cardiac magnetic resonance (CMR) imaging to produce measurements of the aortic root and valve by comparison of accuracy and efficiency with that of three National Health Service (NHS) cardiologists. Methods AI-derived aortic root and valve measurements were recorded alongside manual measurements from three experienced NHS consultant cardiologists (CCs) over three separate sites in the northeast part of the United Kingdom. The study utilised a comprehensive dataset of CMR images, with the intraclass correlation coefficient (ICC) being the primary measure of concordance between the AI and the cardiologist assessments. Patient imaging was anonymised and blinded at the point of transfer to a secure data server.  Results The study demonstrates a high level of concordance between AI assessment of the aortic root and valve with NHS cardiologists (ICC of 0.98). Notably, the AI delivered results in 2.6 seconds (+/- 0.532) compared to a mean of 334.5 seconds (+/- 61.9) by the cardiologists, a statistically significant improvement in efficiency without compromising accuracy. Conclusion AI's accuracy and speed of analysis suggest that it could be a valuable tool in cardiac diagnostics, addressing the challenges of time-consuming and variable clinician-based assessments. This research reinforces AI's role in optimising the patient journey and improving the efficiency of the diagnostic pathway.

Aortic arch shape after arch repair predicts exercise capacity: a multicentre analysis

Aims

Coarctation of the aorta is associated with long-term morbidity including decreased exercise capacity, despite successful repair. In the absence of discrete recoarctation, the haemodynamic mechanism remains unknown. This multicentre study evaluated the relationship between aorta shape, flow, and exercise capacity in patients after arch repair, specifically through the lens of aortic size mismatch and descending aortic (DAo) flow and their association with exercise.

Methods and results

Cardiac magnetic resonance, cardiopulmonary exercise test, and echocardiogram data within 1 year were analysed from 58 patients (age 28 ± 10 years, 48% male) across four centres with history of isolated arch repair. Aortic arch measurements were correlated with % predicted VO2max with subgroup analyses of those with residual arch obstruction, bicuspid aortic valve, and hypertension. Ascending aorta (AAo) to DAo diameter ratio (DAAo/DDAo) was negatively correlated with % predicted VO2max. %DAo flow positively correlated with VO2max. Sub-analyses demonstrated that the negative correlation of DAAo/DDAo with VO2max was maintained only in patients without arch obstruction and with a bicuspid aortic valve. Smaller aortic arch measurements were associated with both hypertension and exercise-induced hypertension.

Conclusion

Aorta size mismatch, due to AAo dilation or small DAo, and associated decreased %DAo flow, correlated significantly with decreased exercise capacity after aortic arch repair. These correlations were stronger in patients without arch obstruction and with a bicuspid aortic valve. Aorta size mismatch and %DAo flow capture multiple mechanisms of altered haemodynamics beyond blood pressure gradient or discrete obstruction and can inform the definition of a successful repair.

The myth of aortic valve annulus changes in aortic valve disease

Background

The characteristics of aortic annulus changes in aortic regurgitation (AR) patients are poorly understood, and predictive factors among aortic valve disease are yet to be established.

Objective

This study seeks to elucidate the pattern of annular size fluctuations across different cardiac phases in AR patients and to identify predictors for annular enlargement during either systole or diastole in aortic valve diseases.

Methods

A retrospective analysis was conducted on 55 patients with severe aortic valve diseases, including 26 patients with aortic stenosis (AS) and 29 with AR, to discern the two groups' contrasting and analogous patterns of annular changes. The patient sample was expanded to 107 to investigate the factors influencing the size of the annulus during different cardiac phases. Based on our findings, patients were then divided into two groups: those with an annulus that is larger during systole (83 patients) and those where the annulus is larger during diastole (24 patients).

Results

Typically, AR patients exhibit a dynamic annulus, with both perimeter and area being largest during mid-systole. These dimensions diminish progressively and then increase again in early diastole, a pattern consistent with observations in AS patients. Among 107 patients, 21% had diastolic enlargement. Systolic measurements would lead to prosthesis undersizing in 17% of these. Male gender and lower systolic annulus minimum relative to body surface area (AnMin index) were predictors of diastolic enlargement, with ROC curve areas of 0.70 and 0.87 for AR and AS, respectively.

Conclusions

Systolic measurements are recommended for AR patients. Gender and the AnMin index are significant predictors, particularly potent in AS patients.

Proximal aorta dilatation in hypertension

Dilation of the proximal aorta is a common clinical manifestation in hypertensive patients. Although it is straightforward to link hypertension with proximal aortic dilation, previous studies on their interrelation have yielded controversial results. Cross-sectional design, methodology of blood pressure assessment, confounding factors like medications, and inconsistent reference values may lead to the paradoxical conclusions. Recently, advances have been made in the exploration of determinants and clinical value of proximal aortic dilatation. Thus, we reviewed these findings and summarized that aortic dilatation may be the consequence of hemodynamic and nonhemodynamic co-factors' combined action. Moreover, proximal aortic dilatation tends to be a predictor for aortic aneurysm dissection or rupture, hypertensive target organ damage as well as cardiovascular events. The present review contributes to a comprehensive understanding of the pathological process of proximal aortic dilatation in hypertension.

Value of aortic volumes assessed by automated segmentation of 3D MRI data in patients with thoracic aortic dilatation: A case-control study

PURPOSE

The purpose of this study was to investigate the benefit of aortic volumes compared to diameters or cross-sectional areas on three-dimensional (3D) magnetic resonance imaging (MRI) in discriminating between patients with dilated aorta and matched controls.

MATERIALS AND METHODS

Sixty-two patients (47 men and 15 women; median age, 66 years; age range: 33-86 years) with tricuspid aortic valve and ascending thoracic aorta aneurysm (TAV-ATAA) and 43 patients (35 men and 8 women; median age, 51 years; age range: 17-76 years) with bicuspid aortic valve and dilated ascending aorta (BAV) were studied. One group of 54 controls matched for age and sex to patients with TAV-ATAA (39 men and 15 women; median age, 68 years; age range: 33-81 years) and one group of 42 controls matched for age and sex to patients with BAV (34 men and 8 women; median age, 50 years; age range: 17-77 years) were identified. All participants underwent 3D MRI, used for 3D-segmentation for measuring aortic length, maximal diameter, maximal cross-sectional area (CSA) and volume for the ascending aorta.

RESULTS

An increase in ascending aorta volume (TAV-ATAA: +107%; BAV: +171% vs. controls; P < 0.001) was found, which was three times greater than the increase in diameter (TAV-ATAA: +29%; BAV: +40% vs. controls; P < 0.001). In differentiating patients with TAV-ATAA from their controls, the indexed ascending aorta volume showed better performances (AUC, 0.935 [95% confidence interval (CI): 0.882-0.989]; accuracy, 88.7% [95% CI: 82.9-94.5]) than indexed ascending aorta length (P < 0.001), indexed ascending aorta maximal diameter (P = 0.003) and indexed ascending aorta maximal CSA (P = 0.03). In differentiating patients with BAV from matched controls, indexed ascending aorta volume showed significantly better performances performance (AUC, 0.908 [95% CI: 0.829-0.987]; accuracy, 88.0% [95% CI: 80.9-95.0]) than indexed ascending aorta length (P = 0.02) and not different from indexed ascending aorta maximal diameter (P = 0.07) or from indexed ascending aorta maximal CSA (P = 0.27) CONCLUSION: Aortic volume measured by 3D-MRI integrates both elongation and luminal dilatation, resulting in greater classification performance than maximal diameter and length in differentiating patients with dilated ascending aorta or aneurysm from controls.

Expert Consensus Statement: Anatomy, Imaging, and Nomenclature of Congenital Aortic Root Malformations

Over the past 2 decades, several categorizations have been proposed for the abnormalities of the aortic root. These schemes have mostly been devoid of input from specialists of congenital cardiac disease. The aim of this review is to provide a classification, from the perspective of these specialists, based on an understanding of normal and abnormal morphogenesis and anatomy, with emphasis placed on the features of clinical and surgical relevance. We contend that the description of the congenitally malformed aortic root is simplified when approached in a fashion that recognizes the normal root to be made up of 3 leaflets, supported by their own sinuses, with the sinuses themselves separated by the interleaflet triangles. The malformed root, usually found in the setting of 3 sinuses, can also be found with 2 sinuses, and very rarely with 4 sinuses. This permits description of trisinuate, bisinuate, and quadrisinuate variants, respectively. This feature then provides the basis for classification of the anatomical and functional number of leaflets present. By offering standardized terms and definitions, we submit that our classification will be suitable for those working in all cardiac specialties, whether pediatric or adult. It is of equal value in the settings of acquired or congenital cardiac disease. Our recommendations will serve to amend and/or add to the existing International Paediatric and Congenital Cardiac Code, along with the Eleventh iteration of the International Classification of Diseases provided by the World Health Organization.

Expert Consensus Statement: Anatomy, Imaging, and Nomenclature of Congenital Aortic Root Malformations

Over the past 2 decades, several categorizations have been proposed for the abnormalities of the aortic root. These schemes have mostly been devoid of input from specialists of congenital cardiac disease. The aim of this review is to provide a classification, from the perspective of these specialists, based on an understanding of normal and abnormal morphogenesis and anatomy, with emphasis placed on the features of clinical and surgical relevance. We contend that the description of the congenitally malformed aortic root is simplified when approached in a fashion that recognizes the normal root to be made up of 3 leaflets, supported by their own sinuses, with the sinuses themselves separated by the interleaflet triangles. The malformed root, usually found in the setting of 3 sinuses, can also be found with 2 sinuses, and very rarely with 4 sinuses. This permits description of trisinuate, bisinuate, and quadrisinuate variants, respectively. This feature then provides the basis for classification of the anatomical and functional number of leaflets present. By offering standardized terms and definitions, we submit that our classification will be suitable for those working in all cardiac specialties, whether pediatric or adult. It is of equal value in the settings of acquired or congenital cardiac disease. Our recommendations will serve to amend and/or add to the existing International Paediatric and Congenital Cardiac Code, along with the Eleventh iteration of the International Classification of Diseases provided by the World Health Organization.

The aorta in humans and African great apes, and cardiac output and metabolic levels in human evolution

Humans have a larger energy budget than great apes, allowing the combination of the metabolically expensive traits that define our life history. This budget is ultimately related to the cardiac output, the product of the blood pumped from the ventricle and the number of heart beats per minute, a measure of the blood available for the whole organism physiological activity. To show the relationship between cardiac output and energy expenditure in hominid evolution, we study a surrogate measure of cardiac output, the aortic root diameter, in humans and great apes. When compared to gorillas and chimpanzees, humans present an increased body mass adjusted aortic root diameter. We also use data from the literature to show that over the human lifespan, cardiac output and total energy expenditure follow almost identical trajectories, with a marked increase during the period of brain growth, and a plateau during most of the adult life. The limited variation of adjusted cardiac output with sex, age and physical activity supports the compensation model of energy expenditure in humans. Finally, we present a first study of cardiac output in the skeleton through the study of the aortic impression in the vertebral bodies of the spine. It is absent in great apes, and present in humans and Neanderthals, large-brained hominins with an extended life cycle. An increased adjusted cardiac output, underlying higher total energy expenditure, would have been a key process in human evolution.

Serial Magnetic Resonance Imaging for Aortic Dilation in Tetralogy of Fallot With Pulmonary Stenosis

Aortic dilation occurs in patients with repaired tetralogy of Fallot (TOF), but the rate of growth is incompletely characterized. The aim of this study was to assess the rates of growth of the aortic root and ascending aorta in a cohort of pediatric and adult patients with sequential magnetic resonance angiography Magnetic Resonance Imaging (MRI) data. Using serial MRI data from pediatric and adult patients with repaired TOF, we performed a retrospective analysis of the rates of growth and associations with growth of the aortic root and ascending aorta. Patients with pulmonary atresia or absent pulmonary valve were excluded. Between years 2005 to 2021, a total of 99 patients were enrolled. A follow-up MRI was performed an average of 5.9 ± 3.7 years from the initial study. For the cohort aged ≥16 years, the mean rate of change in diameter was 0.2 ± 0.5 mm/year at the ascending aorta and 0.2 ± 0.6 mm/year at the sinus of Valsalva. For the entire cohort, the mean change in cross-sectional area indexed to height at the ascending aorta was 7 ± 12 mm2/m/year and at the sinus of Valsalva was 10 ± 16 mm2/m/year. Younger age was associated with higher rates of growth of the sinus of Valsalva while the use of β blockers or angiotensin-converting enzyme inhibitors was associated with a slower rate of growth. There were no cases of aortic dissection in this cohort. We conclude that serial MRI demonstrates a slow rate of growth of the aorta in the TOF.

Comparison of cine cardiac magnetic resonance and echocardiography derived diameters of the aortic root in a large population-based cohort

Transthoracic echocardiography (TTE) and cine cardiac magnetic resonance imaging (CMR) are established imaging methods of the aortic root. We aimed to evaluate the comparability of measurements in TTE and standard cine CMR sequences of the aortic root. Our study included 741 subjects (mean age 63.5 ± 8 years, 43.7% female) from the Hamburg City Health Study (HCHS). Subjects underwent CMR and TTE. Aortic root measurements were performed at the level of the aortic annulus (AoAn), sinus of Valsalva (SoV), and sinotubular junction (STJ) by standard cine CMR in left ventricular long axis and left ventricular outflow tract view. Measurements were performed applying the leading-edge to leading-edge (LL) convention and inner-edge to inner-edge (II) convention in TTE and the II convention in CMR. Inter correlation coefficients (ICCs) demonstrated high inter- and intraobserver reproducibility for CMR and TTE measurements of SoV and STJ (ICCs 0.9–0.98) and moderate reproducibility for AoAn (ICCs 0.68–0.91). CMR measurements of SoV and STJ showed strong agreement with TTE: while correlations were comparable (r = 0.75–0.85) bias was lower with TTE II (bias − 0.1 to − 0.74) versus TTE LL measurements (mean bias − 1.49 to − 2.58 mm). The agreement for AoAn was fair (r = 0.51–0.57) with variable bias (mean bias 0.39–3.9). Standard cine CMR and TTE derived aortic root measurements are reproducible and comparable with higher agreement for TTE II instead of LL measurements. These results support an interchangeable application of TTE and standard CMR for screening of aortic root diseases thereby possibly reducing redundant multimodality imaging.

Proximal Aortic Dilatation and Pulmonary Valve Replacement in Patients with Repaired Tetralogy of Fallot: Is There a Relationship? A Cardiac Magnetic Resonance Imaging Study

Aortopathy is a known complication whose incidence is growing within the population of tetralogy of Fallot (TOF) patients. Its pathology and relationship with other comorbidities remain unclear. This study was designed to determine the prevalence and predictors of proximal aortic dilatation after TOF repair. We retrospectively investigated all patients who underwent follow-up cardiac magnetic resonance imaging (CMR; at least 4 years after TOF repair) between March 2004 and December 2019. The dimensions at the ascending aorta (AAo) and sinus of Valsalva (SoV) levels were measured. Aortic dilatation was defined as an internal aortic diameter that was >2 standard deviation of the previously published normal values. We included 77 patients (mean age 28.9 ± 10.5 years, 41.5% female, mean follow-up of 24.5 ± 8.1 years). AAo and SoV were dilated in 19 (24.6%) and 43 (55.8%) patients, respectively. Patients with dilated AAo and SoV were older during the corrective surgery (p < 0.001 and p = 0.004, respectively) and during CMR (p = 0.002 and 0.024, respectively) than patients without AAo and SoV dilatation. Patients of the dilated AAo group were more likely to have prior palliative shunt (p = 0.008), longer shunt duration (p = 0.005), and a higher degree of aortic valve regurgitation (AR) fraction (p < 0.001) and to undergo pulmonary (PVR) and/or aortic valve replacement (p < 0.001 and p = 0.013, respectively). PVR (p = 0.048, odds ratio = 6.413, and 95% CI = 1.013-40.619) and higher AR fraction (p = 0.031, odds ratio = 1.194, and 95% CI = 1.017-1.403) were independent predictors for AAo dilatation. Aortopathy is a common progressive complication that may require reintervention and lifelong follow-up. Our study shows that proximal aortic dilatation may be attributed to factors that increase the volume overload across the proximal aorta, including late corrective surgery and palliative shunt. We also found that PVR and higher AR fraction are independent predictors of AAo dilatation.

Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant, age-related but highly penetrant condition with substantial intrafamilial and interfamilial variability. MFS is caused by pathogenetic variants in FBN1, which encodes fibrillin-1, a major structural component of the extracellular matrix that provides support to connective tissues, particularly in arteries, the pericondrium and structures in the eye. Up to 25% of individuals with MFS have de novo variants. The most prominent manifestations of MFS are asymptomatic aortic root aneurysms, aortic dissections, dislocation of the ocular lens (ectopia lentis) and skeletal abnormalities that are characterized by overgrowth of the long bones. MFS is diagnosed based on the Ghent II nosology; genetic testing confirming the presence of a FBN1 pathogenetic variant is not always required for diagnosis but can help distinguish MFS from other heritable thoracic aortic disease syndromes that can present with skeletal features similar to those in MFS. Untreated aortic root aneurysms can progress to life-threatening acute aortic dissections. Management of MFS requires medical therapy to slow the rate of growth of aneurysms and decrease the risk of dissection. Routine surveillance with imaging techniques such as transthoracic echocardiography, CT or MRI is necessary to monitor aneurysm growth and determine when to perform prophylactic repair surgery to prevent an acute aortic dissection.

European Association of Cardiovascular Imaging expert consensus paper: a comprehensive review of cardiovascular magnetic resonance normal values of cardiac chamber size and aortic root in adults and recommendations for grading severity

This consensus paper provides a framework for grading of severity of cardiovascular magnetic resonance (CMR) imaging-based assessment of chamber size, function, and aortic measurements. This does not currently exist for CMR measures. Differences exist in the normal reference values between echocardiography and CMR along with differences in methods used to derive these. We feel that this document will significantly complement the current literature and provide a practical guide for clinicians in daily reporting and interpretation of CMR scans. This manuscript aims to complement a recent comprehensive review of CMR normal value publications to recommend cut-off values required for severity grading. Standardization of severity grading for clinically useful CMR parameters is encouraged to lead to clearer and easier communication with referring clinicians and may contribute to better patient care. To this end, the European Association of Cardiovascular Imaging (EACVI) has formed this expert panel that has critically reviewed the literature and has come to a consensus on approaches to severity grading for commonly quantified CMR parameters.

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.

2D cine vs. 3D self-navigated free-breathing high-resolution whole heart cardiovascular magnetic resonance for aortic root measurements in congenital heart disease

BACKGROUND

Cardiovascular magnetic resonance (CMR) is considered the method of choice for evaluation of aortic root dilatation in congenital heart disease. Usually, a cross-sectional 2D cine stack is acquired perpendicular to the vessel's axis. However, this method requires a considerable patient collaboration and precise planning of image planes. The present study compares a recently introduced 3D self-navigated free-breathing high-resolution whole heart CMR sequence (3D self nav) allowing a multiplanar retrospective reconstruction of the aortic root as an alternative to the 2D cine technique for determination of aortic root diameters.

METHODS

A total of 6 cusp-commissure (CuCo) and cusp-cusp (CuCu) enddiastolic diameters were measured by two observers on 2D cine and 3D self nav cross-sectional planes of the aortic root acquired on a 1.5 T CMR scanner. Asymmetry of the aortic root was evaluated by the ratio of the minimal to the maximum 3D self nav CuCu diameter. CuCu diameters were compared to standard transthoracic echocardiographic (TTE) aortic root diameters.

RESULTS

Sixty-five exams in 58 patients (32 ± 15 years) were included. Typically, 2D cine and 3D self nav spatial resolution was 1.1-1.52 × 4.5-7 mm and 0.9-1.153 mm, respectively. 3D self nav yielded larger maximum diameters than 2D cine: CuCo 37.2 ± 6.4 vs. 36.2 ± 7.0 mm (p = 0.006), CuCu 39.7 ± 6.3 vs. 38.5 ± 6.5 mm (p < 0.001). CuCu diameters were significantly larger (2.3-3.9 mm, p < 0.001) than CuCo and TTE diameters on both 2D cine and 3D self nav. Intra- and interobserver variabilities were excellent for both techniques with bias of -0.5 to 1.0 mm. Intra-observer variability of the more experienced observer was better for 3D self nav (F-test p < 0.05). Aortic root asymmetry was more pronounced in patients with bicuspid aortic valve (BAV: 0.73 (interquartile (IQ) 0.69; 0.78) vs. 0.93 (IQ 0.9; 0.96), p < 0.001), which was associated to a larger difference of maximum CuCu to TTE diameters: 5.5 ± 3.3 vs. 3.3 ± 3.8 mm, p = 0.033.

CONCLUSION

Both, the 3D self nav and 2D cine CMR techniques allow reliable determination of aortic root diameters. However, we propose to privilege the 3D self nav technique and measurement of CuCu diameters to avoid underestimation of the maximum diameter, particularly in patients with asymmetric aortic roots and/or BAV.

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.

Central pulse pressure is inversely associated with proximal aortic remodelling

OBJECTIVES

Hypertension leads to aortic stiffening and dilatation but unexpected data from the Framingham Heart Study showed an inverse relationship between brachial pulse pressure and aortic diameter. Aortic dilatation would not only lead to lower pulse pressure but also to a worse prognosis (cardiac events, heart failure). Invasive pressure may be more informative but data are lacking.

AIM

This study evaluated the relationship between invasively measured central blood pressure and proximal aortic diameter.

METHODS

In 71 consecutive patients referred to invasive haemodynamic study, proximal aortic remodelling was evaluated in terms of Z-score, comparing diameters measured at the sinus of Valsalva to the diameter expected according to patients' age, sex and body height. Pressures were recorded directly in the proximal aorta by means of a catheter before coronary assessment.

RESULTS

The mean invasive aortic SBPs and DBPs were 146 ± 23 and 78 ± 13 mmHg, respectively, giving a central pulse pressure (cPP inv) of 68 ± 21 mmHg. Proximal aortic diameter was 34.9 ± 19.4 mm, whereas Z-score was -0.3 ± 1.7. Patients with higher cPPinv showed a significantly lower Z-score (-0.789 vs. 0.155, P = 0.001). cPPinv was inversely related to Z-score (R = -0.271, P = 0.022) independently from age, mean blood pressure and heart rate (β = -0.241, P = 0.011).

CONCLUSION

Aortic root Z-score is inversely associated with invasively measured central pulse pressure in a cohort of patients undergoing invasive coronary assessment. Remodelling at the sinuses of Valsalva may be a compensatory mechanism to limit pulse pressure.

Discrepancies in Measurement of the Thoracic Aorta: JACC Review Topic of the Week

Clinicians often encounter discrepant measurements of the ascending aorta that impede, complicate, and impair appropriate clinical assessment-including key issues of presence or absence of aortic growth, rate of growth, and need for surgical intervention. These discrepancies may arise within a single modality (computed tomography scan, magnetic resonance imaging, or echocardiography) or between modalities. The authors explore the origins and significance of these discrepancies, revealing that some "truth" usually underlies all the discrepant measurements, which individually look at the ascending aorta with different perspectives and dimensional definitions. The authors conclude with a practical "question and answer" section that addresses common specific issues in interpretation and management of patients in the real-world setting.

Reference values of thoracic aorta and pulmonary artery diameters by age and gender in healthy Chinese adults assessed by cardiac magnetic resonance imaging: data from national center for cardiovascular diseases of China

The aim of the study was to define normal ranges for thoracic aorta and pulmonary artery diameters relative to gender, age, body surface area (BSA) and body mass index (BMI) in healthy Chinese adults by cardiac magnetic resonance (CMR). We studied 200 healthy participants (100 men, 100 women; age range from 20-70) by using a 3.0-T CMR system. The diameters of the ascending aorta (AA), main pulmonary artery (PA), proximal descending aorta (DA) and Valsalva sinus (VAS) were measured manually by two experienced doctors on half-Fourier single-shot spin echo (HASTE) and balanced steady-state free precession (bSSFP) cine images. The mean value and age specific and gender adjusted normal limits were calculated. The linear regression analysis were performed between diameters and gender, age, BMI and BSA. The mean and 95% confidence interval(CI) of AA, PA, DA and VAS were 28.95 ± 4.61 mm(95% CI 19.92-37.99 mm), 22.41 ± 2.59 mm(95% CI 17.31-27.47 mm), 20.61 ± 2.96 mm(95% CI 14.81-26.42 mm), 31.15 ± 3.65 mm(95% CI 24.00-38.29 mm), respectively. The gender differences of all the parameters above were statistically significant (all p < 0.01). Both thoracic aorta and pulmonary artery dilates with the increase of age, while AA has the highest dilation rate. The mean PA/AA was 0.79 and showed no gender difference, but there was statistical difference among all age groups (p < 0.01). AA and DA had stronger association with age and BSA than BMI. Age- and gender-specific reference diameters of thoracic aorta and pulmonary artery were provided in healthy Chinese adults. Age and BSA have stronger effects on the ranges of diameters than BMI.

Reference ranges ("normal values") for cardiovascular magnetic resonance (CMR) in adults and children: 2020 update

Cardiovascular magnetic resonance (CMR) enables assessment and quantification of morphological and functional parameters of the heart, including chamber size and function, diameters of the aorta and pulmonary arteries, flow and myocardial relaxation times. Knowledge of reference ranges ("normal values") for quantitative CMR is crucial to interpretation of results and to distinguish normal from disease. Compared to the previous version of this review published in 2015, we present updated and expanded reference values for morphological and functional CMR parameters of the cardiovascular system based on the peer-reviewed literature and current CMR techniques. Further, databases and references for deep learning methods are included.

Dilatation of the Ascending Aorta in Turner Syndrome: Influence of Bicuspid Aortic Valve Morphology and Body Composition

BACKGROUND

Aortic dilatation and bicuspid aortic valve (BAV) are frequent in Turner syndrome (TS). Due to short stature, aortic size index (ASI)-ascending aortic diameter (AD)/body surface area (BSA)-is used to identify aortic dilatation in TS patients. We sought to: 1) describe echocardiographic findings in the largest cohort of Australian women with TS; 2) assess if ASI progresses differently with age in TS BAV compared to non-syndromic BAV; and 3) determine whether adjustment of AD for body composition may be superior to BSA indexation.

METHODS

Transthoracic echocardiography (TTE) data were retrospectively collected on 125 women with TS. Body composition was quantified by dual energy X-ray absorptiometry (DXA) in 60 women within 6 months of baseline TTE. Age-matched females with non-syndromic BAV (n=170) were used as controls for TS patients with BAV.

RESULTS

Mean age of TS women was 28±16 years, and mean height and BSA were 141.6±21.7 cm and 1.4±0.4 m², respectively. Mean AD was 2.5±0.8 cm, and ASI 2.0±0.6 cm/m². Aortic dilatation (ASI >2.0 cm/m²) was present in 42 (34%) patients. Turner syndrome women with BAV (n=34; 27%) had a larger ASI than those with tri-leaflet AV (2.2±0.4 cm/m² vs. 1.7±0.3 cm/m², p<0.001). In the pooled BAV cohort, TS patients had a higher baseline ASI (2.2±0.4 cm/m² vs. 2.1±0.3 cm/m², p=0.02) and greater increase in ASI with age (0.21 mm/m²/year vs. 0.10 mm/m²/year, p=0.01) compared to non-syndromic BAV patients. DXA fat-free mass (r=0.33, p=0.01) and lean mass (r=0.32, p=0.02) correlated with AD, as did BSA (r=0.62, p<0.001).

CONCLUSION

Turner syndrome women with BAV have a greater degree of baseline aortic dilatation and a twofold faster increase in aortic dimension with age when compared to matched women with non-syndromic BAV. Several DXA-derived body composition parameters correlate with aortic size in TS, however BSA appears to be the most robust method of indexation.

Non-invasive determination of pressure recovery by cardiac MRI and echocardiography in patients with severe aortic stenosis: short and long-term outcome prediction

OBJECTIVE

To assess the influence of pressure recovery (PR)-corrected haemodynamic parameters on outcome in patients with aortic stenosis.

METHODS

Aortic stenosis severity parameters were corrected for PR (increase in static pressure due to decreasing dynamic pressure), assessed using transthoracic echocardiography (TTE) or cardiac magnetic resonance imaging (CMR), in patients with aortic stenosis. PR, indexed PR (iPR) and energy loss index (ELI) were determined. Factors that predicted all-cause mortality, and 9-month or 10-year New York Heart Association classification ≥2 were assessed using Cox proportional hazards regression.

RESULTS

A total of 25 patients, aged 68 ± 10 years, were included. PR was 17 ± 6 mmHg using CMR, and CMR correlated with TTE measurements. PR correction using CMR data reduced the AS-severity classification in 12-20% of patients, and correction using TTE data reduced the AS-severity classification in 16% of patients. Age (Wald 4.774) was a statistically significant predictor of all-cause mortality; effective orifice area (Wald 3.753) and ELI (Wald 3.772) almost reached significance.

CONCLUSIONS

PR determination may result in significant reclassification of aortic stenosis severity and may hold value in predicting all-cause mortality.

Heritability of haemodynamics in the ascending aorta

Blood flow in the vasculature can be characterised by dimensionless numbers commonly used to define the level of instabilities in the flow, for example the Reynolds number, Re. Haemodynamics play a key role in cardiovascular disease (CVD) progression. Genetic studies have identified mechanosensitive genes with causal roles in CVD. Given that CVD is highly heritable and abnormal blood flow may increase risk, we investigated the heritability of fluid metrics in the ascending aorta calculated using patient-specific data from cardiac magnetic resonance (CMR) imaging. 341 participants from 108 British Caucasian families were phenotyped by CMR and genotyped for 557,124 SNPs. Flow metrics were derived from the CMR images to provide some local information about blood flow in the ascending aorta, based on maximum values at systole at a single location, denoted max, and a 'peak mean' value averaged over the area of the cross section, denoted pm. Heritability was estimated using pedigree-based (QTDT) and SNP-based (GCTA-GREML) methods. Estimates of Reynolds number based on spatially averaged local flow during systole showed substantial heritability ([Formula: see text], [Formula: see text]), while the estimated heritability for Reynolds number calculated using the absolute local maximum velocity was not statistically significant (12-13%; [Formula: see text]). Heritability estimates of the geometric quantities alone; e.g. aortic diameter ([Formula: see text], [Formula: see text]), were also substantially heritable, as described previously. These findings indicate the potential for the discovery of genetic factors influencing haemodynamic traits in large-scale genotyped and phenotyped cohorts where local spatial averaging is used, rather than instantaneous values. Future Mendelian randomisation studies of aortic haemodynamic estimates, which are swift to derive in a clinical setting, will allow for the investigation of causality of abnormal blood flow in CVD.

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.

Neo-aortic Root Dilatation, Aortic Stiffness, and Ventricular interactions in Long-Term Follow-Up After the Ross Procedure in Childhood

Patients after the Ross procedure are at risk for right (RV) and left ventricular (LV) dysfunction due to neo-aortic and pulmonary dysfunction. While neo-aortic root dilatation has been related to LV dysfunction, the potential contributions of aortic stiffness and ventricular interactions have not been evaluated. Patients status post Ross procedure up to age 18 years with cardiac magnetic resonance (CMR) exam from 2007 to 2018 were retrospectively reviewed. Aortic pulse wave velocity (PWV) was calculated from phase contrast and angiogram images. RV and LV peak global longitudinal (GLS) and circumferential strain (GCS) were measured using tissue tracking software. Multivariable regression was performed for variables associated with parameters of LV function. In 58 patients (median age 20.5 years at CMR exam), male gender, longer time since Ross procedure, aortic root dilatation, and lower RV ejection fraction (EF) were associated with decreased LV EF. There was no association with LV late gadolinium enhancement or neo-aortic or conduit regurgitation. LV GCS and GLS also correlated with RV GCS, RV GLS and PWV. In multivariable analysis, the relation of RV and LV systolic function, but not aortic measurements, remained significant. In conclusion, in long-term follow-up after pediatric Ross procedure, RV function rather than aortic root size or aortic stiffness most closely relates to LV function. Ventricular interactions may impact decision-making on timing of conduit intervention, which could differ from established criteria in populations with only aortic or pulmonary valve disease. Further study is warranted to evaluate possible association with clinical outcome.

Multimodality imaging in bicuspid aortic valve

Bicuspid aortic valve (BAV) patients are at increased risk of valve dysfunction and ascending aorta aneurysm. Imaging techniques are essential to establish diagnosis, identify complications and indicate surgical treatment. Transthoracic echocardiography (TTE) is the imaging technique of choice to diagnose BAV, valve morphotype and valvular dysfunction in clinical practice. However, it can be less precise in assessing the aortic root and proximal ascending aorta, and visualization of the mid-distal ascending aorta and the arch may be difficult in some adults where cardiac magnetic resonance (CMR) and computed tomography, using multiplanar reconstructions, are better at assessing aortic diameters. Although valvular dysfunction is very variable, almost half of the patients have more than mild aortic valve disease. TTE is the most effective and accurate test for evaluating the severity of valvular dysfunction and guiding appropriate management decisions. Aorta dilation is a common finding in patients with BAV. The pattern of aortic dimensions has been categorized in three aortic phenotypes: no-dilation phenotype, ascending aorta phenotype and root phenotype. Controversial data exist regarding the relationship between BAV morphology and aorta dilation phenotype. The assessment of aortic stiffness (measuring distensibility or the velocity of propagation of flow) has raised special interest in order to predict progressive aorta dilation. However, current data indicates that BAV aortas do not show altered stiffness compared to those associated with a tricuspid valve with a similar aorta size. Moreover, novel 4D-flow CMR sequences have been crucial in the evaluation of abnormal ascending aorta flow, showing that flow in the aorta of BAV patients is asymmetric and includes the formation of large vortices. Such flow abnormalities are thought to produce changes in wall shear stress which has been associated with extracellular matrix dysregulation. The key points to understand familial screening and the recommendations for establishing the follow-up and therapeutic management of BAV patients are exposed in the review. The main objective of this article is to review the advantages and limitations of the imaging techniques in the diagnosis and management of BAV and the best strategies in the use of multimodality imaging.

Validation of thoracic aortic dimensions on ECG-triggered SSFP as alternative to contrast-enhanced MRA

Objectives

Assessment of thoracic aortic dimensions with non-ECG-triggered contrast-enhanced magnetic resonance angiography (CE-MRA) is accompanied with motion artefacts and requires gadolinium. To avoid both motion artefacts and gadolinium administration, we evaluated the similarity and reproducibility of dimensions measured on ECG-triggered, balanced steady-state free precession (SSFP) MRA as alternative to CE-MRA.

Methods

All patients, with varying medical conditions, referred for thoracic aortic examination between September 2016 and March 2018, who underwent non-ECG-triggered CE-MRA and SSFP-MRA (1.5 T) were retrospectively included (n = 30). Aortic dimensions were measured after double-oblique multiplanar reconstruction by two observers at nine landmarks predefined by literature guidelines. Image quality was scored at the sinus of Valsalva, mid-ascending aorta and mid-descending aorta by semi-automatically assessing the vessel sharpness.

Results

Aortic dimensions showed high agreement between non-ECG-triggered CE-MRA and SSFP-MRA (r = 0.99, p < 0.05) without overestimation or underestimation of aortic dimensions in SSFP-MRA (mean difference, 0.1 mm; limits of agreement, − 1.9 mm and 1.9 mm). Intra- and inter-observer variabilities were significantly smaller with SSFP-MRA for the sinus of Valsalva and sinotubular junction. Image quality of the sinus of Valsalva was significantly better with SSFP-MRA, as fewer images were of impaired quality (3/30) than in CE-MRA (21/30). Reproducibility of dimensions was significantly better in images scored as good quality compared to impaired quality in both sequences.

Conclusions

Thoracic aortic dimensions measured on SSFP-MRA and non-ECG-triggered CE-MRA were similar. As expected, SSFP-MRA showed better reproducibility close to the aortic root because of lesser motion artefacts, making it a feasible non-contrast imaging alternative.

Key Points

• SSFP-MRA provides similar dimensions as non-ECG-triggered CE-MRA.

• Intra- and inter-observer reproducibilities improve for the sinus of Valsalva and sinotubular junction with SSFP-MRA.

• ECG-triggered SSFP-MRA shows better image quality for landmarks close to the aortic root in the absence of cardiac motion.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-06963-x) contains supplementary material, which is available to authorized users.

Three-dimensional volumetric measurement of the aortic root compared to standard two-dimensional measurements using cardiac computed tomography

INTRODUCTION

Two-dimensional measurements are self-evidently limited when seeking accurately to represent the three-dimensional complexity of the aortic root. Volumetric measurement, therefore, seems an ideal alternative for a more accurate assessment.

MATERIALS AND METHODS

We retrospectively analyzed 123 individuals undergoing cardiac computed tomography. We measured the dimensions of the sinuses of Valsalva using routine multiplanar short axis imaging. Three conventional two-dimensional methods were applied to measure the dimensions of the sinuses. These involved bisecting center of sinus-to-center of interleaflet triangle measures, along with center of sinus-to-center of sinus, and largest sinus-to-sinus measurements. We then quantified the volumes of the root using the volume-rendering method.

RESULTS

The mean dimensions of the sinuses were significantly greater when measured using the largest sinus-to-sinus method as opposed to center of sinus-to-center of interleaflet triangle and center of sinus-to-center of sinus methods (33.6 ± 3.6 mm vs. 31.1 ± 3.1 mm and 30.9 ± 3.3 mm, p < .0001). The mean root volume of 13.6 ± 4.2 ml showed the strongest correlation with the mean dimensions of the sinuses of Valsalva measured using the bisecting method (R² = .8401, p < .0001).

CONCLUSIONS

By using two- and three-dimensional measurements, we have provided average data for the structurally normal aortic root. The differences and correlations encountered should be noted when evaluating and following changes in the diseased root.

Multimodality Assessment of Thoracic Aortic Dimensions: Comparison of Computed Tomography Angiography, Magnetic Resonance Imaging, and Echocardiography Measurements

PURPOSE

The purpose of this study was to compare thoracic aortic measurements between computed tomography (CT), magnetic resonance imaging (MRI), and transthoracic echocardiography (TTE).

MATERIALS AND METHODS

A total of 127 patients (mean age: 45±18 y, 49% male) who had undergone CT and MRI evaluation of the thoracic aorta at a single tertiary referral hospital within a 6-month interval between 2007 and 2017 were included in this retrospective study. TTE studies performed within the same 6-month interval were also evaluated. Thoracic aortic measurements were blindly evaluated using multiple techniques and were compared between modalities.

RESULTS

There was no significant difference in maximum aortic root diameter between CT and MRI when using the inner lumen-to-inner lumen technique (mean difference: 0.2±1.4 mm, P=0.51) or the outer lumen-to-outer lumen technique (mean difference: 0.5±1.4 mm, P=0.07). There were no significant differences between CT and MRI at any other level except for the distal descending aorta (20.2±4.6 vs. 19.8±4.6 mm, P<0.001). However, aortic root measurements by TTE using the leading edge-to-leading edge technique were significantly smaller compared with maximum aortic root diameters using the inner lumen-to-inner lumen and outer lumen-to-outer lumen techniques by both CT (mean difference: 4.9±2.7 mm, P<0.001 and 7.4±2.8 mm, P<0.001, respectively) and MRI (mean difference: 4.8±3.2 mm, P<0.001 and 8.2±3.0 mm, P<0.001, respectively).

CONCLUSIONS

There is excellent agreement in thoracic aortic measurements between CT and MRI. However, TTE significantly underestimates maximum aortic root diameter compared with CT and MRI. Therefore, caution should be used when interpreting small apparent changes in aortic root diameters between TTE and CT or MRI.

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.

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.

Interval changes in aortic peak velocity and wall shear stress in patients with bicuspid aortic valve disease

Bicuspid aortic valve (BAV) is associated with abnormal valve-mediated hemodynamics including high velocity jets and elevated wall shear stress (WSS). This study investigated interval changes in flow and WSS in a multi-year follow-up study. This cross-sectional study included n = 44 patients with BAV (age = 44.9 ± 12 years), n = 17 patients with tricuspid aortic valve and thoracic aortic dilatation (TAV with dilation, age = 54.6 ± 16.5 years), and n = 9 healthy controls (age = 49.3 ± 14.7 years) underwent baseline and serial aortic 4D flow MRI (follow-up duration: BAV: 2.6 ± 0.7 years, TAV with dilation: 2.7 ± 0.5 years, controls: 1.1 ± 0.5 years). Data analysis included quantification of aortic dimensions, peak systolic velocities, as well as regional 3D WSS in the ascending aorta. At baseline, BAV patients demonstrated uniformly elevated peak velocity and WSS compared to TAV with dilation and control groups (peak velocity 2.2 m/s vs. 1.6 m/s vs. 1.5 m/s, p < 0.004; WSS: 0.74 Pa vs. 0.45 Pa vs. 0.55 Pa, p < 0.001). For BAV, peak velocity increased from baseline to follow up (2.2 ± 0.8 to 2.3 ± 0.9 m/s, p < 0.001) while WSS decreased (0.74 ± 0.22 to 0.65 ± 0.21 Pa, p < 0.001). Aortic growth was minimal for both BAV (0.05 cm/year) and TAV with dilation (0.03-0.04 cm/year) patients. For BAV patients, increase of ascending aorta peak velocities indicated worsening of valve function at follow-up. Compared to TAV with dilation patients, BAV patients demonstrated a reduction in WSS which may indicate a compensatory mechanism to reduce elevated WSS forces by aortic remodeling.

Comparison of dynamic changes in aortic diameter during the cardiac cycle measured by computed tomography angiography and transthoracic echocardiography

OBJECTIVE

This study aimed to examine the relationship between dynamic changes in aortic diameter and corresponding measurement methods.

METHODS

Consecutive adult (nonaneurysmal) patients being surgically treated for heart disease (mean age, 51 ± 11 years; range, 29-76 years; N = 25) were included in this study. All patients underwent transthoracic echocardiography (TTE), computed tomography angiography (CTA), and intraoperative ultrasound (IOUS). Anteroposterior diameters were measured at 1 cm above the junction of the aortic sinus, the proximal 1 cm of the innominate artery, and the midpoint of the two.

RESULTS

The average diameter of the proximal ascending aorta in systole/diastole measured by IOUS was 32.07 ± 2.03/30.27 ± 2.05 mm (paired t-test: difference, 1.80 ± 0.46 mm; P < .001). The average diameters of the proximal ascending aorta measured by nonelectrocardiography-gated CTA and TTE were 31.45 ± 1.97 mm and 29.7 ± 1.84 mm, respectively. The average diameter of the mid and distal ascending aorta in systole/diastole measured by IOUS was 32.35 ± 1.95/30.57 ± 1.94 mm (paired t-test: difference, 1.78 ± 0.44 mm; P < .001) and 32.32 ± 1.92/30.67 ± 1.90 mm (paired t-test: difference, 1.65 ± 0.42 mm; P < .001), respectively. The average diameter of the mid and distal ascending aorta measured by CTA was 31.74 ± 1.92 mm and 31.59 ± 1.96 mm, respectively. At each location, the difference in the aortic diameter between systole and diastole was statistically significant (all P values <.001; paired t-test). The minimum and maximum changes in the diameter between systole and diastole were 0.90 mm and 2.70 mm. In all, 96% (24/25) of the average diameters derived from IOUS and CTA at the three locations were within the concordance limit in systole, and 92% to 100% (23/25 to 25/25) were within the concordance limit in diastole. The average diameters derived from IOUS and TTE images of the proximal ascending aorta were within the bounds of the concordance limit 92% (23/25) of the time in systole and 100% (25/25) of the time in diastole. The average diameters derived from CTA and TTE images of the proximal ascending aorta were within the bounds of the concordance limit 88% (22/25) of the time. Pearson correlation coefficients between these groups ranged from 0.905 to 0.982 (all P values <.01).

CONCLUSIONS

The ascending aorta diameters measured by nonelectrocardiography-gated CTA and TTE were consistent with the IOUS measurements.

Novel insights by 4D Flow imaging on aortic flow physiology after valve-sparing root replacement with or without neosinuses

OBJECTIVES

This study was undertaken to evaluate the flow dynamics in the aortic root after valve-sparing root replacement with and without neosinuses of Valsalva reconstruction, by exploiting the capability of 4D Flow imaging to measure in vivo blood velocity fields and 3D geometric flow patterns.

METHODS

Ten patients who underwent valve-sparing root replacement utilizing grafts with neosinuses or straight tube grafts (5 cases each) were evaluated by 4D Flow imaging at a mean of 46.5 months after surgery. We used in-house processing tools to quantify relevant bulk flow variables (flow rate, stroke volume, peak velocity and mean velocity), wall shear stresses and the amount of flow rotation characterizing the region enclosed by the graft and the aortic valve leaflets.

RESULTS

Despite bulk flows with similar peak velocities, flow rates and stroke volumes (P = 0.31-1.00), the neosinuses graft was associated with a lower mean velocity (P < 0.03) and magnitude of wall shear stress along the axial direction of the vessel wall (P < 0.05) at the proximal root level but remained comparable along the circumferential direction (P = 0.22-1.0) to the straight tube graft. Flow rotation was evidently and systematically higher in the neosinuses grafts, characterized by streamline rotations higher than 270°, nearly triple that of tubular grafts (10.3 ÷ 14.0% of all aortic streamline vs 2.2 ÷ 5.7%, P = 0.008).

CONCLUSIONS

Recreation of the sinuses of Valsalva during valve-sparing root replacement is associated with significantly lower wall shear stress and organized vortical flows at the level of the sinus that are not evident using the straight tube graft. These findings need confirmation in larger studies and could have important implications in terms of aortic valve durability.

Screening for thoracic aortic pathology: Clinical practice in a single tertiary center

OBJECTIVE

The aim is to present current clinical practice of thoracic aorta screening in a tertiary referral center. We identified how often imaging techniques were used for screening and established the value of transthoracic echocardiography (TTE) in comparison with computed tomography (CT) to detect aortic dilation. We also investigated which additional abnormalities of the heart, aorta or smaller arteries were discovered.

DESIGN

All patients ≥15 years who visited our tertiary center in 2012-2016 for first thoracic aortic screening were retrospectively included. Diameters of the sinus of Valsalva (SoV) and maximum ascending aorta (AA) were compared between TTE and CT. The sensitivity and specificity of TTE to detect aortic dilation (≥40 mm) was assessed with CT as reference standard. Intracardiac abnormalities found with TTE and arterial abnormalities found with CT were identified.

RESULTS

In total 349 patients (155 men, age 41 ± 15 years, 10% genetic mutation) were included. Screening was performed with TTE only in 35% and with TTE and CT in 65%. Patients who underwent TTE only were younger, had less often hypertension and less often a family history of aortic pathology. Although there was a good correlation between TTE and CT, the diameters measured with TTE were typically lower (SoV -1.0, 95%CI -6.6 to 4.7 and AA -0.4, 95%CI -6.5 to 5.8). Sensitivity of TTE for detecting aortic dilation was 61% (SoV) and 57% (AA) and specificity was 96% (SoV) and 100% (AA). Valve abnormalities, ventricular dilation or reduced ventricular function was found with TTE in 26 patients (7%). In 47 patients (13%) ascending aortic dilation was diagnosed and in 10 patients (4%) relevant peripheral arterial abnormalities were identified using CT.

CONCLUSIONS

Most often patients received both TTE and CT (65%). Since TTE showed a low sensitivity to detect aortic dilation, CT imaging is advised at least once in patients referred for thoracic aortic screening.

Reference Values for Mid-Ascending Aorta Diameters by Transthoracic Echocardiography in Adults

We sought to characterize mid-ascending aorta diameter reference values by age, sex, and body surface area (BSA) in a large echocardiography laboratory practice-based cohort. All subjects with transthoracic echocardiograms with mid-ascending aorta diameter measure from January 2004 to December 2009 were identified, and medical records were reviewed for medical history and anthropometric data. Those with aortic valve disease or replacement, congenital heart disease, any connective tissue or inflammatory disease that may affect the aorta, or known aortic aneurysm (>55 mm) were excluded. Mid-ascending aorta diameter was measured in a standardized manner using "leading edge to leading edge" technique at end-diastole. Of 27,839 eligible subjects, 16,620 did not have history of hypertension and were included in the analysis (56.3% female; mean age 52.0 ± 15.8 years), mean mid-ascending aorta diameter 31.7 ± 4.1 mm. Females had smaller diameter than males (30.5 ± 3.7 mm vs 33.3 ± 4.0 mm; p <0.001). Subjects with history of hypertension (n = 11,219; not included in the analysis) had larger mid-ascending aorta diameter compared with normotensive subjects (33.9 ± 3.8 mm vs 31.7 ± 4.1 mm; p < 0.001). Age had the greatest correlation with aortic size (r = 0.55), followed by sex (r = 0.35) and BSA (r = 0.35). Nomograms for predicted mid-ascending aorta diameter were generated at the 95th percentile using quantile regression for subjects without hypertension stratified by age, sex, and BSA. In conclusion, mid-ascending aorta diameter is predominantly associated with sex, age, and BSA. The nomograms established by this study may serve as useful reference values for echocardiographic screening and surveillance.

MiR-145 expression and rare NOTCH1 variants in bicuspid aortic valve-associated aortopathy

MicroRNAs (miRNAs) may serve as elegant tool to improve risk stratification in bicuspid aortic valve (BAV)-associated aortopathy. However, the exact pathogenetic pathway by which miRNAs impact aortopathy progression is unknown. Herewith, we aimed to analyze the association between circulating miRNAs and rare variants of aortopathy-related genes. 63 BAV patients (mean age 47.3±11.3 years, 92% male) with a root dilatation phenotype, who underwent aortic valve+/-proximal aortic surgery at a single institution (mean post-AVR follow-up 10.3±6.9 years) were analyzed. A custom-made HaloPlex HS panel including 20 aortopathy-related genes was used for the genetic testing. miRNAs were extracted from whole blood and miRNA analysis was performed using miRNA-specific assay. Study endpoint was the association between circulating miRNAs and rare genetic variants in the aortopathy gene panel. The study cohort was divided into a subgroup with rare variants vs. a subgroup without rare variants based on the presence of rare variants in the respective genes (i.e., at least one variant present). The genetic analysis yielded n = 6 potentially and likely pathogenic rare variants within the NOTCH1 gene as being the most common finding. Univariate analysis between blood miRNAs and NOTCH1 variants revealed a significantly lower expression of miR-145 in the subgroup of patients with NOTCH1 variants vs. those without NOTCH1 variants (i.e., delta Ct 4.95±0.74 vs. delta Ct 5.57±0.78, p = 0.04). Our preliminary data demonstrate a significant association between blood miR-145 expression and the presence of rare NOTCH1 variants. This association may be indicative of a specific pathogenetic pathway in the development of genetically-triggered bicuspid aortopathy.

Evidence of subannular and left ventricular morphological differences in patients with bicuspid versus tricuspid aortic valve stenosis: magnetic resonance imaging-based analysis

Objectives

Prospective analysis of left ventricular (LV) morphological/functional parameters in patients with bicuspid versus tricuspid aortic valve (TAV) stenosis undergoing aortic valve replacement (AVR) surgery.

Methods

A total of 190 consecutive patients with BAV ( n  = 154) and TAV stenosis ( n  = 36) (mean age 61 ± 8 years, 65% male) underwent AVR ± concomitant aortic surgery from January 2012 through May 2015. All patients underwent preoperative cardiac magnetic resonance imaging in order to evaluate: (i) left ventricular outflow tract (LVOT) dimensions, (ii) length of anterior mitral leaflet (AML), (iii) end-systolic and end-diastolic LV wall thickness, (iv) LV area, (v) LV end-systolic and end-diastolic diameters (LVESD, LVEDD), (vi) LV end-diastolic and end-systolic volumes (LVEDV, LVESV) and (vii) maximal diameter of aortic root. These parameters were compared between the two study groups.

Results

The LVOT diameter was significantly larger in BAV patients (21.7 ± 3 mm in BAV vs 18.9 ± 3 mm in TAV, P  < 0.001). Moreover, BAV patients had significantly longer AML (24 ± 3 mm in BAV vs 22 ± 4 mm in TAV, P  = 0.009). LVEDV and LVESV were significantly larger in BAV patients (LVEDV: 164.9 ± 68.4 ml in BAV groups vs 126.5 ± 53.1 ml in TAV group, P  = 0.037; LVESV: 82.1 ± 57.9 ml in BAV group vs 52.9 ± 25.7 ml in TAV group, P  = 0.008). A strong linear correlation was found between LVOT diameter and aortic annulus diameter in BAV patients ( r  = 0.7, P  < 0.001), whereas significantly weaker correlation was observed in TAV patients ( r  = 0.5, P  = 0.006, z  = 1.65, P  = 0.04). Presence of BAV morphology was independently associated with larger LVOT diameters (OR 9.0, 95% CI 1.0-81.3, P  = 0.04).

Conclusions

We found relevant differences in LV morphological/functional parameters between BAV and TAV stenosis patients. Further investigations are warranted in order to determine the cause of these observed differences.