Reduced Aortic Elasticity and Dilatation Are Associated With Aortic Regurgitation and Left Ventricular Hypertrophy in Nonstenotic Bicuspid Aortic Valve Patients

Mechanisms of Aortic Dilation in Patients With Bicuspid Aortic Valve: JACC State-of-the-Art Review

Bicuspid aortic valve is the most common congenital heart disease and exposes patients to an increased risk of aortic dilation and dissection. Aortic dilation is a slow, silent process, leading to a greater risk of aortic dissection. The prevention of adverse events together with optimization of the frequency of the required lifelong imaging surveillance are important for both clinicians and patients and motivated extensive research to shed light on the physiopathologic processes involved in bicuspid aortic valve aortopathy. Two main research hypotheses have been consolidated in the last decade: one supports a genetic basis for the increased prevalence of dilation, in particular for the aortic root, and the second supports the damaging impact on the aortic wall of altered flow dynamics associated with these structurally abnormal valves, particularly significant in the ascending aorta. Current opinion tends to rule out mutually excluding causative mechanisms, recognizing both as important and potentially clinically relevant.

Feasibility of Wave Intensity Analysis from 4D Cardiovascular Magnetic Resonance Imaging Data

Congenital heart defects (CHD) introduce haemodynamic changes; e.g., bicuspid aortic valve (BAV) presents a turbulent helical flow, which activates aortic pathological processes. Flow quantification is crucial for diagnostics and to plan corrective strategies. Multiple imaging modalities exist, with phase contrast magnetic resonance imaging (PC-MRI) being the current gold standard; however, multiple predetermined site measurements may be required, while 4D MRI allows for measurements of area (A) and velocity (U) in all spatial dimensions, acquiring a single volume and enabling a retrospective analysis at multiple locations. We assessed the feasibility of gathering hemodynamic insight into aortic hemodynamics by means of wave intensity analysis (WIA) derived from 4D MRI. Data were collected in n = 12 BAV patients and n = 7 healthy controls. Following data acquisition, WIA was successfully derived at three planes (ascending, thoracic and descending aorta) in all cases. The values of wave speed were physiological and, while the small sample limited any clinical interpretation of the results, the study shows the possibility of studying wave travel and wave reflection based on 4D MRI. Below, we demonstrate for the first time the feasibility of deriving wave intensity analysis from 4D flow data and open the door to research applications in different cardiovascular scenarios.

A Left ventricle remodeling in patients with bicuspid aortic valve

PURPOSE

We assessed the impact of bicuspid aortic valve (BAV), aortic stenosis (AS), and regurgitation (AR) on the metrics of left ventricular (LV) remodeling, as measured by electrocardiogram (ECG), transthoracic echocardiography (TTE), and cardiac magnetic resonance (CMR).

METHODS

This retrospective CMR study included 11 patients with both AS and AR (BAV-ASR), 30 with AS (BAV-AS), 28 with AR (BAV-AR), 47 with neither AS nor AR (BAV-no_AS/AR), and 40 with trileaflet aortic valve (TAV-no_AS/AR). CMR analysis included the LV end-diastolic volume index (LVEDVi), mass index (LVMi), and extracellular volume fraction (ECV). The Sokolow-Lyon and Cornell products by ECG and TTE-derived E/e' were measured.

RESULTS

There were no differences in the ECG, TTE, and CMR parameters between BAV-no_AS/AR and TAV-no_AS/AR. However, the presence of aortic valve dysfunction resulted in an elevated Sokolow-Lyon product for BAV-ASR (p = 0.017) and BAV-AR (p = 0.001), as well as increased Cornell product (p = 0.04) and E/e' (p < 0.001) for BAV-AS compared with BAV-no_AS/AR. LVEDVi and LVMi were elevated in patients with BAV-ASR and BAV-AR compared with those with BAV-no_AS/AR (LVEDVi: 101 ± 29 ml/m² and 112 ± 32 ml/m² vs. 74 ± 15 ml/m², p = 0.005 and p < 0.001, LVMi: 75 ± 7 g/m² and 64 ± 14 g/m² vs. 47 ± 9 g/m², respectively; p < 0.001). There was no difference in ECV between the BAV and TAV-no_AS/AR subgroups.

CONCLUSION

Normally functioning BAV did not result in LV remodeling. However, concomitant AV dysfunction was associated with statistically significant morphological remodeling.

Identification of recurrent variants implicated in disease in bicuspid aortic valve patients through whole-exome sequencing

Bicuspid aortic valve (BAV) is the most common congenital heart defect in human beings, with an estimated prevalence in the general population of between 0.5 and 2%. Moreover, BAV is the most common cause of aortic stenosis in the pediatric population. Patients with BAV may have no symptoms for life, and some of them may progress to aortic stenosis. Genetic factors increase the susceptibility and development of BAV. However, the pathogenesis and BAV are still unclear, and more genetic variants are still needed for elucidating the molecular mechanism and stratification of patients. The present study carried out screening of variants implicated in disease in BAV patients. The whole-exome sequencing (WES) was performed in 20 BAV patients and identified 40 different heterozygous missense mutations in 36 genes (MIB2, FAAH, S100A1, RGS16, MAP3K19, NEB, TTN, TNS1, CAND2, CCK, KALRN, ATP10D, SLIT3, ROS1, FABP7, NUP205, IL11RA, NPR2, COL5A1, CUBN, JMJD1C, ANXA7, TRIM8, LGR4, TPCN2, APOA5, GPR84, LRP1, NCOR2, AKAP11, ESRRB, NGB, AKAP13, WWOX, KCNJ12, ARHGEF1). The mutations in these genes were identified as recurrent variants implicated in disease by in silico prediction tool analysis. Nine genes (MIB2, S100A1, TTN, CCK, NUP205, LGR4, NCOR2, ESRRB, and WWOX) among the 36 genes were identified as variants implicated in disease via unanimous agreement of in silico prediction tool analysis and sequenced in an independent cohort of 137 BAV patients to validate the results of WES. BAV patients carrying these variants demonstrated reduced left ventricular ejection fractions (LVEF) (63.8 ± 7.5% vs. 58.4 ± 5.2%, P < 0.001) and larger calcification volume [(1129.3 ± 154) mm³ vs. (1261.8 ± 123) mm³, P < 0.001]. The variants in TTN, NUP205 and NCOR2 genes are significantly associated with reduced LVEF, and the variants in S100A1, LGR4, ESRRB, and WWOX genes are significantly associated with larger calcification volume. We identified a panel of recurrent variants implicated in disease in genes related to the pathogenesis of BAV. Our data speculate that these variants are promising markers for risk stratification of BAV patients with increased susceptibility to aortic stenosis.

The association between cardiac magnetic resonance-derived aortic stiffness parameters and aortic dilation in young adults with bicuspid aortic valve: With and without coarctation of aorta

Background

Bicuspid aortic valve (BAV) is associated with progressive aortic dilation. Studies in aortopathies have shown a correlation between increased aortic stiffness and aortic dilation. We aimed to evaluate aortic stiffness measures as predictors of progressive aortic dilation by cardiac magnetic resonance (CMR) in BAV patients.

Methods

This is a retrospective study of 49 patients with BAV (median age 21.1 years at first CMR visit) with ≥2 CMR at the Wisconsin Adult Congenital Heart Disease Program (WAtCH). Circumferential aortic strain, distensibility, and β-stiffness index were obtained from CMR-derived aortic root cine imaging, and aortic dimensions were measured at aortic root and ascending aorta. A linear mixed-model and logistic regression were used to identify important predictors of progressive aortic dilation.

Results

Over a median of 3.8 years follow-up, the annual growth rates of aortic root and ascending aorta dimensions were 0.25 and 0.16 mm/year, respectively. Aortic strain and distensibility decreased while β-stiffness index increased with age. Aortic root strain and distensibility were associated with progressive dilation of the ascending aorta. Baseline aortic root diameter was an independent predictor of >1 mm/year growth rate of the aortic root (adjusted OR 1.34, 95 % CI 1.03-1.74, p = 0.028). Most patients (61 %) had coexisting coarctation of aorta. Despite the higher prevalence of hypertension in patients with aortic coarctation, hypertension or coarctation had no effect on baseline aorta dimensions, stiffness, or progressive aortic dilation.

Conclusion

Some CMR-derived aortic stiffness parameters correlated with progressive aortic dilation in BAV and should be further investigated in larger and older BAV cohorts.

Failure properties of ascending thoracic aortic aneurysms with dysfunctional tricuspid aortic valves

OBJECTIVES

Ascending thoracic aortic aneurysms (ATAAs) often coexist with dysfunctional tricuspid aortic valves (TAVs). How valvular pathology relates to the aortic wall mechanical properties requires detailed examination.

METHODS

Intact-wall and layer-specific mechanical properties from 40 and 21 patients with TAV-ATAAs, respectively, were studied using uniaxial tensile testing, longitudinally and circumferentially. Failure stress (tensile strength), failure stretch (extensibility) and peak elastic modulus (stiffness) measurements, along with histological assays of thickness and elastin/collagen contents, were compared among patients with no valvular pathology (NVP), aortic stenosis (AS) or aortic insufficiency (AI).

RESULTS

Intact-wall stiffness longitudinally and medial strength and stiffness, in either direction, were significantly lower in AI patients than in AS and NVP patients. Intact-wall/medial thickness and extensibility in either direction were significantly lower in AS patients than in AI and NVP patients. In contrast, intact-wall/medial stiffness circumferentially was significantly higher in AS patients than in NVP patients, consistent with the significantly increased medial collagen in AS patients. Failure properties and medial thickness and elastin/collagen contents were significantly lower (more impaired) in females. The left lateral was the thickest quadrant in NVP patients, but the 4 quadrants were equally thick in AS and AI patients. There were significant differences in strength and stiffness among quadrants, which varied however in the 3 patient groups.

CONCLUSIONS

The aortic wall load-bearing capacity was impaired in patients with ATAA in the presence of TAV stenosis or insufficiency. These findings lend biomechanical support to the current guidelines suggesting lower thresholds for elective ascending aorta replacement in cases of aortic valve surgery.

Aortic strain in bicuspid aortic valve: an analysis

Bicuspid aortic valve (BAV) is monitored by transthoracic echocardiography and computed tomography (CT) angiography. However, it does not have any early marker of disease progression. This study evaluated speckle-tracking echocardiography (STE) aortic and left ventricular (LV) strain prognostic values, their discriminative power, and their correlation with the degree of valvular regurgitation. We conducted a retrospective analysis of a prospectively enrolled cohort of 45 diagnosed with BAV and 20 gender and age matched controls. We performed 2D-STE aortic and LV strain analysis of the selected population. The cohort was followed-up during a median period of 19.9 months (IQR 12.9-25.2), and outcomes (hospital admission for heart failure (HF), aortic valve replacement (AVR), and death) were determined. The mean patient age was 46.6 ± 15.5 years and 80 % were male. LV indexed volumes and aortic diameter were higher in BAV patients. LV global longitudinal strain (GLS) was impaired (p < 0.001) and aortic GLS was significantly augmented (p = 0.027) in BAV patients. Aortic global circumferential strain (GCS) did not vary between groups. Aortic diameter was the best parameter related to BAV (AUC 0.92) and aortic GLS was best correlated with significant AR (AUC 0.76). AVR was the only outcome observed and its only predictor was indexed LV end-diastolic volume. BAV had impaired LV-GLS values. Aortic GLS was abnormally augmented in BAV patients, which might reflect higher aortic diameters that distorted strain calculations. STE aortic strain is related to AR but does not appear to be a reliable predictor of surgery in BAV patients, at 19 months.

Comprehensive assessment of local and regional aortic stiffness in patients with tricuspid or bicuspid aortic valve aortopathy using magnetic resonance imaging

BACKGROUND

We aimed to provide a comprehensive aortic stiffness description using magnetic resonance imaging (MRI) in patients with ascending thoracic aorta aneurysm and tricuspid (TAV-ATAA) or bicuspid (BAV) aortic valve.

METHODS

This case-control study included 18 TAV-ATAA and 19 BAV patients, with no aortic valve stenosis/severe regurgitation, who were 1:1 age-, gender- and central blood pressures (BP)-matched to healthy volunteers. Each underwent simultaneous aortic MRI and BP measurements. 3D anatomical MRI provided aortic diameters. Stiffness indices included: regional ascending (AA) and descending (DA) aorta pulse wave velocity (PWV) from 4D flow MRI; local AA and DA strain, distensibility and theoretical Bramwell-Hill (BH) model-based PWV, as well as regional arch PWV from 2D flow MRI.

RESULTS

Patient groups had significantly higher maximal AA diameter (median[interquartile range], TAV-ATAA: 47.5[42.0-51.3]mm, BAV: 45.0[41.0-47.0]mm) than their respective controls (29.1[26.8-31.8] and 28.1[26.0-32.0]mm, p < 0.0001), while BP were similar (p ≥ 0.25). Stiffness indices were significantly associated with age (ρ ≥ 0.33), mean BP (arch PWV: ρ = 0.25, p = 0.05; DA distensibility: ρ = -0.30, p = 0.02) or AA diameter (arch PWV: ρ = 0.28, p = 0.03; DA PWV: ρ = 0.32, p = 0.009). None of them, however, was significantly different between TAV-ATAA or BAV patients and their matched controls. Finally, while direct PWV measures were significantly correlated to BH-PWV estimates in controls (ρ ≥ 0.40), associations were non-significant in TAV-ATAA and BAV groups (p ≥ 0.18).

CONCLUSIONS

The overlap of MRI-derived aortic stiffness indices between patients with TAV or BAV aortopathy and matched controls highlights another heterogeneous feature of aortopathy, and suggests the urgent need for more sensitive indices which might help better discriminate such diseases.

[Role of magnetic resonance imaging in patients with aortic stenosis before and after replacement of the valve]

Risk stratification among patients with aortic stenosis remains inadequate, and there is a clinical need for the correct identification of high-risk patients who would benefit from aortic valve intervention before developing left ventricular decompensation. Since the publication of the results of the PARTNER study, transcatheter aortic valve implantation (TAVI) has become the method of choice for aortic valve stenosis in inoperable patients and is a real alternative to conventional surgical replacement of the aortic valve in high-risk patients. In planning TAVI and postoperative monitoring of a patient from imaging methods, the leading role is played by echocardiography and multispiral computed tomography. However, in recent years, the interest of researchers in the use of magnetic resonance imaging in this category of patients has increased. The review article examines the potential role of magnetic resonance imaging in patients with aortic stenosis before and after TAVI.

Thoracic Aortic Aneurysm Growth in Bicuspid Aortic Valve Patients: Role of Aortic Stiffness and Pulsatile Hemodynamics

Background

Bicuspid aortic valve (BAV) is the most common congenital cardiac abnormality. A thoracic aortic aneurysm (TAA) is present in ≈50% of BAV patients, who also have an 8‐fold higher risk of aortic dissection than the general population. Because the health of the aorta is directly reflected in its stiffness and pulsatile hemodynamics, we hypothesized that measures of aortic stiffness and arterial load would be associated with TAA growth in BAV.

Methods and Results

Twenty‐nine unoperated participants with TAA due to BAV who had serial imaging were recruited. Aortic stiffness and steady and pulsatile arterial load were evaluated with validated methods that integrate arterial tonometry with echocardiography. TAA growth was assessed retrospectively based on available imaging, blinded to hemodynamic status. Multivariable linear regression assessed associations of aortic stiffness and hemodynamic variables with TAA growth, adjusting for potential confounders. Overall, 66% of participants were men. Mean±SD for age, baseline aneurysm size, growth rate, and follow‐up time were 57.2±8.3 years, 46.9±3.6 mm, 0.75±0.81 mm/y, and 2.9±3.3 years, respectively. We found that greater aortic stiffness (β±SE for carotid‐femoral pulse wave velocity: 0.30±0.13. P=0.03) and aortic characteristic impedance (β±SE: 0.46±0.18, P=0.02), as well as lower total arterial and proximal aortic compliance (β±SE: −0.44±0.21, P=0.05, and −0.63±0.16, P=0.001, respectively) were independently associated with faster aneurysm growth.

Conclusions

In patients with TAA due to BAV, measures of greater aortic stiffness and pulsatile arterial load indicate an association with accelerated aneurysm expansion. Assessing arterial hemodynamics may be useful for risk stratification and disease monitoring in TAA patients with BAV.

Causes, Diagnosis, Risk Stratification and Treatment of Bicuspid Aortic Valve Disease: An Updated Review

The most common congenital heart disease is the bicuspid aortic valve. Understanding the pathophysiology and the altered hemodynamics is a key component for the diagnosis, risk stratification and treatment. Among others, aortic valve stenosis is the most common complication. Treatment strategies vary depending on the severity of the disease, particularly the dilation of the aorta playing a major role. Together with valve replacement, transcatheter aortic valve implantation is now considered as an alternative option with good results. With this review we would like to discuss the causes, diagnostic methods, risk stratification and treatment strategies of the bicuspid aortic valve.

Variability of MRI Aortic Stiffness Measurements in a Multicenter Clinical Trial Setting: Intraobserver, Interobserver, and Intracenter Variability of Pulse Wave Velocity and Aortic Strain Measurement

PURPOSE

To assess intraobserver, interobserver, and scan-rescan variability of MRI aortic stiffness measurements in a multicenter trial setting.

MATERIALS AND METHODS

This study was a retrospective analysis of prospectively collected data in a multicenter prospective clinical trial (clinicaltrials.gov ID NCT01870739). Forty-five adult patients (31 men; mean age, 58 years ± 12 [standard deviation]; 15 patients per center; three centers) with arterial hypertension underwent standardized 3-T baseline MRI assessments between June and September 2014. Aortic strain was calculated from maximum and minimum aortic area measurements repeated three times by three readers at three aortic levels on three retrospectively gated axial gradient-echo (GRE) data sets. Pulse wave velocity (PWV) was assessed three times by five readers as Δx/Δt: Δx was measured on a parasagittal GRE image of the aortic arch, and Δt was extracted from ascending and descending aortic velocity curves created on three axial phase-contrast acquisitions. Intraobserver, interobserver, and scan-rescan variability was calculated using percentage coefficient of variation (COV).

RESULTS

Aortic strain variability was lowest at the level of the distal descending aorta (DDA) with median COVs of 1.6% for intraobserver variability, 4.0% for interobserver variability, and 10.3% for scan-rescan variability. It was highest at the ascending aorta (AA) with COVs of 3.6% for intraobserver variability, 10.7% for interobserver variability, and 19.8% for scan-rescan variability. Variability of PWV was low: 0.7% for intraobserver variability, 1.5% for interobserver variability, and 8.1% for scan-rescan variability.

CONCLUSION

Low variability can be achieved for aortic strain and PWV measurements in a multicenter trial setting using standardized MRI protocols. Although COV was lower when measuring aortic strain at DDA compared with AA, variability was acceptable at both anatomic locations.Supplemental material is available for this article.© RSNA, 2020.

Impact of valve morphology, hypertension and age on aortic wall properties in patients with coarctation: a two-centre cross-sectional study

OBJECTIVE

We aimed to investigate the combined effects of arterial hypertension, bicuspid aortic valve disease (BAVD) and age on the distensibility of the ascending and descending aortas in patients with aortic coarctation.

DESIGN

Cross-sectional study.

SETTING

The study was conducted at two university medical centres, located in Berlin and London.

PARTICIPANTS

A total of 121 patients with aortic coarctation (ages 1-71 years) underwent cardiac MRI, echocardiography and blood pressure measurements.

OUTCOME MEASURES

Cross-sectional diameters of the ascending and descending aortas were assessed to compute aortic area distensibility. Findings were compared with age-specific reference values. The study complied with the Strengthening the Reporting of Observational Studies in Epidemiology statement and reporting guidelines.

RESULTS

Impaired distensibility (below fifth percentile) was seen in 37% of all patients with coarctation in the ascending aorta and in 43% in the descending aorta. BAVD (43%) and arterial hypertension (72%) were present across all ages. In patients >10 years distensibility impairment of the ascending aorta was predominantly associated with BAVD (OR 3.1, 95% CI 1.33 to 7.22, p=0.009). Distensibility impairment of the descending aorta was predominantly associated with arterial hypertension (OR 2.8, 95% CI 1.08 to 7.2, p=0.033) and was most pronounced in patients with uncontrolled hypertension despite antihypertensive treatment.

CONCLUSION

From early adolescence on, both arterial hypertension and BAVD have a major impact on aortic distensibility. Their specific effects differ in strength and localisation (descending vs ascending aorta). Moreover, adequate blood pressure control is associated with improved distensibility. These findings could contribute to the understanding of cardiovascular complications and the management of patients with aortic coarctation.

Altered ascending aortic wall shear stress in patients with corrected atrioventricular septal defect: a comprehensive cardiovascular magnetic resonance and 4D flow MRI evaluation

AIM

In patients after atrioventricular septal defect correction, altered geometry leads to a changed position and subsequent flow over the left ventricular outflow tract. We hypothesised that this altered flow may influence haemodynamics in the ascending aorta.

METHODS

In total, 30 patients after atrioventricular septal defect correction (age 27.6 ± 12.8 years) and 28 healthy volunteers (age 24.8 ± 13.7 years) underwent 4D flow cardiovascular magnetic resonance. Left ventricular ejection fraction and mean and peak wall shear stress calculated at ascending aortic peak systole were obtained from cardiovascular magnetic resonance. Left ventricular outflow tract data including velocity and diameter were obtained from echocardiography.

RESULTS

Patients showed a higher mean (911 ± 173 versus 703 ± 154 mPa, p = 0.001) and peak ascending aortic wall shear stress (1264 ± 302 versus 1009 ± 240 mPa, p = 0.001) compared to healthy volunteers. Increased blood flow velocities over the left ventricular outflow tract (1.49 ± 0.30 m/s versus 1.22 ± 0.20 m/s, p &lt; 0.001) correlated well with mean and peak ascending aortic wall shear stress (r = 0.67, p &lt; 0.001 and r = 0.77, p &lt; 0.001).

CONCLUSION

After atrioventricular septal defect correction, increased wall shear stress was observed, which correlated to velocities over the left ventricular outflow tract. These findings imply that altered outflow tract geometry contributes to changed aortic haemodynamics.

Aortic Wall Elastic Properties in Case of Bicuspid Aortic Valve

Purpose of the Review

Bicuspid aortic valve (BAV) is associated with a significant risk of development of aneurysm and dissection of the ascending thoracic aorta. Development of what is called BAV associated aortopathy is particularly heterogeneous with an uncertain prognosis and with no prognostic biomarkers except for the aortic diameter. This situation leads to an important variability of the therapeutic strategy of this aortopathy. By reviewing the literature on aortic stiffness in the case of BAV, we aimed at evaluating its potential prognostic role in the development of aortic dilatation.

Recent Findings

Studies evaluating aortic stiffness, with ultrasound or magnetic resonance imaging, converge toward the description of an increased segmental aortic stiffness in BAV patients regardless of age, diameter or aortic level, from the root to the arch. Even though there is a lack of longitudinal studies evaluating the progression of aortic dilatation, new data have recently shown the potential prognostic role of the maximal rate of systolic distension of the aortic wall with magnetic resonance imaging.

Summary

Although the use of aortic distensibility calculation is a simple evaluation of stiffness that could be easily transposed in daily practice, its interpretation remains uncertain. New arterial stiffening indicators seem more promising but need a stronger validation.

Size and Stiffness of the Pulmonary Autograft after the Ross Procedure in Children

Progressive dilatation of the pulmonary autograft is one of the greatest concerns after the Ross procedure. Increased stress in the arterial wall may cause changes in the elastic properties of the pulmonary autograft, and thus lead to pathological dilatation. The present study aimed to investigate the changes in the autograft diameter and stiffness during follow-up after the Ross procedure. A total of ten patients underwent the Ross procedure at our institution between 2003 and 2011. Echocardiography was used to measure the diameters of the pulmonary autograft at the level of the annulus, sinus of Valsalva, and sinotubular junction. The stiffness index was calculated from the angiographic data, and compared with that of 16 age-matched control children. The diameters of the pulmonary autograft increased throughout the follow-up period, particularly at the level of the sinus of Valsalva and at the sinotubular junction. The aortic root was stiffer in Ross patients compared with control children (7.9 ± 1.8 vs. 3.9 ± 0.7 immediately postoperatively, p < 0.01; 10.1 ± 2.8 vs. 4.2 ± 1.4 at 5 years postoperatively, p < 0.01). Although no significant relationship was found between the stiffness index and the autograft diameter, the stiffness index tended to increase over time. Dilatation of the pulmonary autograft was accompanied by progressive change in aortic stiffness. Longer follow-up is warranted to clarify the impact of this change in aortic stiffness on autograft failure.

The role of ventricular-arterial coupling in cardiac disease and heart failure: assessment, clinical implications and therapeutic interventions. A consensus document of the European Society of Cardiology Working Group on Aorta & Peripheral Vascular Diseases, European Association of Cardiovascular Imaging, and Heart Failure Association

Ventricular-arterial coupling (VAC) plays a major role in the physiology of cardiac and aortic mechanics, as well as in the pathophysiology of cardiac disease. VAC assessment possesses independent diagnostic and prognostic value and may be used to refine riskstratification and monitor therapeutic interventions. Traditionally, VAC is assessed by the non-invasive measurement of the ratio of arterial (Ea) to ventricular end-systolic elastance (Ees). With disease progression, both Ea and Ees may become abnormal and the Ea/Ees ratio may approximate its normal values. Therefore, the measurement of each component of this ratio or of novel more sensitive markers of myocardial (e.g. global longitudinal strain) and arterial function (e.g. pulse wave velocity) may better characterize VAC. In valvular heart disease, systemic arterial compliance and valvulo-arterial impedance have an established diagnostic and prognostic value and may monitor the effects of valve replacement on vascular and cardiac function. Treatment guided to improve VAC through improvement of both or each one of its components may delay incidence of heart failure and possibly improve prognosis in heart failure. In this consensus document, we describe the pathophysiology, the methods of assessment as well as the clinical implications of VAC in cardiac diseases and heart failure. Finally, we focus on interventions that may improve VAC and thus modify prognosis.

Gender Related Association between Arterial Stiffness and Aortic Root Geometry

BACKGROUND

The gender-related change in aortic morphology by arterial stiffness has not been well studied. This study was performed to investigate the association between brachial-ankle pulse wave velocity (baPWV) and aortic root size according to gender.

METHODS

A total of 263 consecutive subjects (63.2 ± 10.6 years, 71.1% men) without overt cardiovascular disease who underwent both baPWV measurement and transthoracic echocardiography on the same day were retrospectively analyzed. The diameters of the aortic annulus (AN), sinus of Valsalva (SV), sinotubular junction (STJ), and ascending aorta (AA) were measured using 2-dimensional echocardiography.

RESULTS

The body surface area (BSA)-corrected diameters of AN, SV, STJ, and AA were significantly higher in women than in men. Univariable analyses showed that baPWV was significantly correlated with SV/BSA and STJ/BSA in men, and with SV/BSA, STJ/BSA, and AA/BSA in women (p < 0.05 for each). In men, however, these associations disappeared in multiple linear regression models after controlling for potential confounders (p > 0.05 for each). In women, the associations of baPWV with diameters of STJ/BSA (β = 0.407, p < 0.001) and AA/BSA (β = 0.391, p = 0.005) remained significant in the same multivariate models. Women-specific correlation between aortic root size and baPWV was also similarly demonstrated in age-matched analyses (n = 61 in each gender).

CONCLUSIONS

Among Korean adult without overt cardiovascular disease, the association between increased arterial stiffness and aortic root dilatation is stronger in women than in men.

Aortic stiffness in aortic stenosis assessed by cardiovascular MRI: a comparison between bicuspid and tricuspid valves

Objectives

To compare aortic size and stiffness parameters on MRI between bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients with aortic stenosis (AS).

Methods

MRI was performed in 174 patients with asymptomatic moderate-severe AS (mean AVAI 0.57 ± 0.14 cm²/m²) and 23 controls on 3T scanners. Valve morphology was available/analysable in 169 patients: 63 BAV (41 type-I, 22 type-II) and 106 TAV. Aortic cross-sectional areas were measured at the level of the pulmonary artery bifurcation. The ascending and descending aorta (AA, DA) distensibility, and pulse wave velocity (PWV) around the aortic arch were calculated.

Results

The AA and DA areas were lower in the controls, with no difference in DA distensibility or PWV, but slightly lower AA distensibility than in the patient group. With increasing age, there was a decrease in distensibility and an increase in PWV. After correcting for age, the AA maximum cross-sectional area was higher in bicuspid vs. tricuspid patients (12.97 [11.10, 15.59] vs. 10.06 [8.57, 12.04] cm², p < 0.001), but there were no significant differences in AA distensibility (p = 0.099), DA distensibility (p = 0.498) or PWV (p = 0.235). Patients with BAV type-II valves demonstrated a significantly higher AA distensibility and lower PWV compared to type-I, despite a trend towards higher AA area.

Conclusions

In patients with significant AS, BAV patients do not have increased aortic stiffness compared to those with TAV despite increased ascending aortic dimensions. Those with type-II BAV have less aortic stiffness despite greater dimensions. These results demonstrate a dissociation between aortic dilatation and stiffness and suggest that altered flow patterns may play a role.

Key Points

• Both cellular abnormalities secondary to genetic differences and abnormal flow patterns have been implicated in the pathophysiology of aortic dilatation and increased vascular complications associated with bicuspid aortic valves (BAV).

• We demonstrate an increased ascending aortic size in patients with BAV and moderate to severe AS compared to TAV and controls, but no difference in aortic stiffness parameters, therefore suggesting a dissociation between dilatation and stiffness.

• Sub-group analysis showed greater aortic size but lower stiffness parameters in those with BAV type-II AS compared to BAV type-I.

Electronic supplementary material

The online version of this article (10.1007/s00330-018-5775-6) contains supplementary material, which is available to authorized users.

Abnormal aortic stiffness in patients with bicuspid aortic valve: phenotypic variation determined by magnetic resonance imaging

The aim of this study was to assess aortic stiffness in patients with bicuspid aortic valve (BAV), and to determine if differences exist among the BAV phenotypes. Stiffness was measured by pulse wave velocity (PWV) determined using velocity-encoded magnetic resonance imaging (VENC-MRI). VENC-MRI was performed in 100 BAV patients and 45 normal controls. PWV was determined between the mid ascending and mid descending aorta. The BAV phenotypes were characterized using steady-state free precession (SSFP) images acquired across the face of the aortic valve, and classified as follows: right-left cusp (R-L) fusion, right and non-coronary cusp (R-NC) fusion, and left and non-coronary cusp (L-NC) fusion. The following BAV phenotypes were identified: 76 R-L, 23 R-NC, and 1 L-NC fusion. BAV patients demonstrated significantly greater PWV compared to normal controls, after adjusting for age (9.16 vs. 3.83 m/s; p < 0.0001). Furthermore, PWV was significantly greater in patients with R-NC fusion than those with R-L fusion phenotype (12.27 vs. 7.97 m/s; p < 0.001). There was significantly increased PWV from VENC-MRI in BAV patients compared to normal controls. Thisis the first to demonstrate the association of different BAV phenotypes and aortic stiffness. VENC-MRI PWV assessment potentially represents a novel parameter for enhanced surveillance and may alter surgical triage of aorta in this high risk group.

Ascending Aorta and Myocardial Mechanics in Patients with "Clinically Normal" Bicuspid Aortic Valve

Aortic valve dysfunction and aortic wall changes are well-known complications of bicuspid aortic valve (BAV) disease. The aim of the present study was to investigate whether a remodeling process of the left ventricle (LV) is present in patients with isolated BAV. Twenty-two consecutive patients (39 ± 15 years, 9 males) with clinically normal BAV and 18 age- and gender-matched control subjects (37 ± 10 years, 9 males) were included. Cardiovascular magnetic resonance (CMR) imaging was performed to evaluate LV function, aortic valve morphology, aortic orifice area, and ascending aorta (AA) dimensions. Tissue-tracking analysis was applied to assess LV systolic and diastolic myocardial mechanics in the longitudinal, circumferential, and radial direction and AA circumferential strain (CS). No significant difference was observed between BAV and controls regarding LV ejection fraction and LV mass index. Tissue-tracking analysis demonstrated that BAV patients had significantly impaired LV systolic and diastolic myocardial mechanics. BAV patients had also significantly lower AA CS compared with controls. At multivariate analysis, the presence of BAV was the only variable significantly and independently related to the impaired AA and LV systolic myocardial mechanics. In conclusion, LV myocardial deformation properties are impaired among BAV patients. The impairment of LV systolic mechanics observed in BAV patients appears to be related only to the congenital abnormality of the aortic valve itself.

Arterioventricular interaction after coarctation repair

BACKGROUND

Hypertension is common in patients with coarctation of the aorta (CoA), even after successful repair. Increased aortic stiffness has been implicated in the pathology of CoA-associated hypertension. This study aimed to investigate aortic vascular function and its relationship with hypertension in well-repaired CoA-patients at long-term follow-up. Furthermore, we assessed the additive effect of hypertension to adverse arterioventricular coupling associated with increased aortic stiffness.

METHODS

Twenty-two CoA-patients (age 30 ± 10.6 years) with successful surgical repair (n = 12) or balloon angioplasty (BA) (n = 10) between 3 months and 16 years of age with a follow-up of >10 years and 22 healthy controls underwent cardiac magnetic resonance imaging (CMR), at mean follow-up of 29.3 years, to study aortic pulse wave velocity (PWV), aortic distensibility, global left ventricular (LV) function, LV dimensions, and LV myocardial deformation.

RESULTS

CoA-patients had significantly increased aortic arch PWV (5.6 ± 1.9 m/s vs. 4.5 ± 1.0 m/s, P = .02) and decreased distensibility (4.5 ± 1.8 × 10-3 mmHg^-1 vs. 5.8 ± 1.8 × 10-3 mmHg^-1, P = .04) compared to controls. Significant differences in aortic arch PWV were found between hypertensive patients, normotensive patients and controls (6.1 ± 1.8 m/s vs. 4.9 ± 1.9 m/s and 4.5 ± 1.0 m/s, respectively, P = .03). Aortic arch PWV and distensibility were correlated with systolic blood pressure (R = 0.37 and R = -0.37, respectively, P = .03 for both). Global LV function, LV mass, LV dimensions and myocardial deformation were similar in CoA-patients when compared to controls.

CONCLUSIONS

Central aortic stiffness is significantly increased in well-repaired CoA-patients long-term after repair, and is associated with hypertension. Global LV function, myocardial deformation indices and LV dimensions are however preserved.

Myocardial repolarization is affected in patients with ascending aortic aneurysm

OBJECTIVE

Ascending aortic aneurysm (AAA) is one of the major causes of ventricular diastolic dysfunction. Diastolic dysfunction can induce ventricular repolarization dispersion. Nevertheless, myocardial repolarization dispersion is not yet to be fully evaluated in patients with AAA. We aimed to evaluate ventricular repolarization using QT and Tp-Te interval and corrected (c) Tp-Te/QT ratio in patients with AAA.

METHODS

One hundred-four patients with AAA without coronary artery disease (CAD) served as the aneurysm group and 82 patients having a normal aortic diameter as the control group. All patients underwent transthoracic echocardiography (TTE) for measurements of LV diastolic function and underwent electrocardiography (ECG) to calculate RR, QT, Tp-Te intervals and QT dispersion. Bazett's formula was used to calculate QTc and cTp-Te intervals. cTp-Te/QT ratio was also calculated.

RESULTS

The groups were similar according to basal characteristics. We found left ventricular diastolic properties were impaired and QT dispersion, QTc interval, and both of Tp-Te and cTp-Te intervals were significantly prolonged in the aneurysm group than the control group. There were also significant correlations between TTE and ECG parameters. On multivariate linear regression analysis, indexed ascending aortic dimension (AAoD), LA diameter and E/e' ratio were independent predictors of ventricular repolarization dispersion in AAA patients.

CONCLUSIONS

Our study results showed that patients with AAA may have an increased risk for ventricular arrhythmogenesis because of deteriorated the left ventricular diastolic function.

Impact of Bicuspid Aortic Valve Morphology on Aortic Valve Disease and Aortic Dilation in Pediatric Patients

Bicuspid aortic valve (BAV) is the most common congenital heart defect. BAV is associated with aortic stenosis and insufficiency, and aortic dilation in adult groups, but data in pediatric groups are limited. We sought to assess the impact of BAV morphology on aortic valve disease and aortic dilation in pediatric patients. We performed a retrospective review of all echocardiograms in patients with isolated BAV who were followed at our institution from July 2002 to July 2012. BAV morphology, aortic valve stenosis and/or insufficiency, and aortic dimensions were measured manually. Comparisons were made between right-left cusp fusion (RL) and right-noncoronary cusp fusion (RN) BAV morphologies. Generalized least square models were fit to analyze the impact of specific variables on aortic dilation. There were 1075 echocardiograms in 366 patients (72% male) with isolated BAV. Aortic valve insufficiency and stenosis were more common in RN (p < 0.001 for both). The median aortic sinus Z score was higher in the RL (0.47; IQR - 0.31 to 1.44) than in the RN group (0.02; - 0.83 to 0.82) (p < 0.001). There was no difference in median ascending aorta Z score between groups. Patients with the highest weights had larger aortas (p < 0.001), but the absolute difference between the highest and lowest weight groups was small (1.5 mm). The impact of BAV morphology on aortic valve disease and aortic dilation in pediatric patients presages that seen in adults. Patient body weight does not make significant clinical impacts on aortic diameters, suggesting that Z scores for aortic diameters should be based on ideal body weights.

Feature Tracking Cardiac MRI Reveals Abnormalities in Ventricular Function in Patients With Bicuspid Aortic Valve and Preserved Ejection Fraction

Subclinical systolic and diastolic left ventricular (LV) dysfunction has been reported in previous echocardiographic studies on congenital bicuspid aortic valve (BAV). Patients with BAV commonly undergo evaluation with magnetic resonance imaging, and feature-tracking cardiovascular magnetic resonance (CMR-FT) is an emerging technique that assesses myocardial strain using standard cine sequences. This study investigated differences in myocardial strain between patients with BAV with preserved ejection fraction (EF) and controls using CMR-FT. Patients with isolated BAV and preserved EF, who had previously undergone CMR (n = 42; mean age, 41.2 ± 13.9) were compared with controls (n = 19; 36.6 ± 9.8; P = .2). Investigational CMR-FT strain analysis software was used to measure circumferential systolic and diastolic strain values, as well as standard LV volumetric and functional parameters. The majority of patients with BAV had mild or no valve dysfunction, and LV myocardial mass end-diastolic volume indices were similar between groups. Peak diastolic circumferential strain rate was lower in patients with BAV than in controls (0.89 ± 0.27 vs 1.21 ± 0.21 s-1, P = .003). After adjusting for covariates, only myocardial mass index was independently associated with peak circumferential systolic strain and diastolic strain rate. Feature-tracking CMR can identify abnormalities of LV strain in a clinical cohort of asymptomatic patients with BAV with preserved EF. Decreases in circumferential diastolic strain rate in patients with BAV suggest evidence of early diastolic dysfunction.

4D flow MRI, cardiac function, and T1 -mapping: Association of valve-mediated changes in aortic hemodynamics with left ventricular remodeling

BACKGROUND

Patients with bicuspid aortic valve (BAV) show altered hemodynamics in the ascending aorta that can be assessed by 4D flow MRI.

PURPOSE

Comprehensive cardiac MRI was applied to test the hypothesis that BAV-mediated changes in aortic hemodynamics (wall shear stress [WSS] and velocity) are associated with parameters of left ventricular (LV) remodeling.

STUDY TYPE

Retrospective data analysis.

POPULATION

Forty-nine BAV patients (mean age = 50.2 ± 13.5, 62% male).

FIELD STRENGTH/SEQUENCE

Balanced steady-state free precession (bSSFP)-CINE, pre- and postcontrast T₁ mapping with modified Look-Locker inversion recovery (MOLLI), time-resolved 3D phase-contrast (PC) MRI with three-directional velocity encoding (4D flow MRI) at 1.5 and 3T.

ASSESSMENT

Quantification of LV volumetric data and myocardial mass, extracellular volume fraction (ECV), aortic valve stenosis (AS), and regurgitation (AR). 3D aortic segmentation, quantification of peak systolic velocities, and 3D WSS in the ascending aorta (AAo), arch, and descending aorta (DAo).

STATISTICAL TESTS

Two-sided nonpaired t-test to compare subgroups. Pearson correlation coefficient for correlations between aortic hemodynamics and LV parameters.

RESULTS

Of the 49 BAV patients, 35 had aortic valve dysfunction (AS [n = 7], AR [n = 16], both AS and AR [n = 12]). Mean systolic WSS in the AAo, peak systolic velocities in the AAo and arch, and LV mass were significantly higher (P < 0.001) in the AS/AR group compared to the patients without AS/AR. In the complete group, we observed significant relationships between increased LV mass and elevated peak systolic velocity (r = 0.57, r = 0.58; P < 0.001) and WSS in the AAo and arch, respectively (r = 0.54, r = 0.46; P < 0.001). We detected an association between ECV and WSS in the AAo (r = 0.38, P = 0.02). These relations did not hold true for patients without AV dysfunction.

DATA CONCLUSION

AS and AR in BAV patients have a major impact on elevated aortic peak velocities and WSS that were associated with parameters of LV remodeling.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017.

PIEZORESISTIVE STRAIN SENSOR APPLICATION IN EVALUATION OF MOUSE AORTIC MEDIA CUSHIONS EFFECTIVENESS AND SPONTANEOUS MYOGENIC CONTRACTION

The aortic media realized Windkessel vessel functions and maintain sustained ventricle ejection balance during cardiac circle. Wheatstone bridge circuit piezoresistive strain sensor had desirable sensing properties to investigate aortic cushion features. In this study, Wheatstone bridge sensor was used to evaluate quick stretching-induced aortic efficient cushions and spontaneous myogenic contractions. Mice aortic specimens were loosely hooked and stabilized to [Formula: see text][Formula: see text]mm stainless steel pin and strain sensor, whereas the other side was hooked and shows increasing specimen length. Specimen isometric tension and rhythmic spontaneous myogenic contraction were recorded. Isometric tension and spontaneous myogenic response at initial length ([Formula: see text] and ultimate length ([Formula: see text] were evaluated. Aortic specimen significantly eliminated mechanical rigid oscillations. The recovery to baseline time was significantly shortened at [Formula: see text] ([Formula: see text][Formula: see text]ms and [Formula: see text] ms at [Formula: see text] and [Formula: see text], respectively, but [Formula: see text][Formula: see text]ms and [Formula: see text][Formula: see text]ms in no-load test). High Ca[Formula: see text] incubation prolonged the recovery time to baseline at [Formula: see text] and [Formula: see text] ([Formula: see text][Formula: see text]ms and [Formula: see text][Formula: see text]ms, respectively) and suggested Ca[Formula: see text] decreased efficient cushion. Moreover, strain sensor successfully recorded the enhanced rhythmic spontaneous myogenic contractions in isometric specimen. Wheatstone bridge circuit sensor reflected the significance of efficient cushions under mechanical preload, which absolutely captured rhythmic myogenic contractions of mice aortic specimen.

Characteristics of Carotid Artery Structure and Mechanical Function and Their Relationships with Aortopathy in Patients with Bicuspid Aortic Valves

Patients with a bicuspid aortic valve (BAV) often have proximal aortic dilatation and systemic vascular dysfunction. We hypothesized that BAV patients would have different carotid artery structural and functional characteristics compared to tricuspid aortic valve (TAV) patients. In 28 patients with surgically confirmed BAV and 27 patients with TAV, intima media thickness (IMT), number of plaques, fractional area change (FAC), global circumferential strain (GCS), and standard deviation of CS (SD-CS) in both common carotid arteries were assessed using duplex ultrasound and velocity vector imaging (VVI). Patients with BAV were younger and had less co-morbidity, but showed a significantly larger ascending aorta (43.3 ± 7.5 vs. 37.0 ± 6.2 mm, p < 0.001) and a higher prevalence of aortopathy (61 vs. 30%, p = 0.021) than those with TAV. BAV patients showed a significantly lower IMT and fewer plaques. Although FAC and GCS were not significantly different between the two groups, they tended to be lower in the BAV group when each group was divided into three subgroups according to age. There was a significant age-dependent increase in IMT and decreases in FAC and GCS in the TAV group (p = 0.005, p = 0.001, p = 0.002, respectively), but this phenomenon was not evident in the BAV group (p = 0.074, p = 0.248, p = 0.394, respectively). BAV patients with aortopathy showed a higher SD-CS than those without aortopathy (p = 0.040), reflecting disordered mechanical function. In conclusion, BAV patients have different carotid artery structure and function compared with TAV patients, suggesting intrinsic vascular abnormalities that are less affected by established cardiovascular risk factors and more strongly related to the presence of aortopathy.

Aortic root stiffness affects the kinematics of bioprosthetic aortic valves

Objectives

In this study, the influence of aortic root distensibility on the haemodynamic parameters and valve kinematics of a bioprosthetic aortic valve was investigated in a controlled in vitro experiment.

Methods

An Edwards INTUITY Elite 21 mm sutureless aortic valve (Edwards Lifesciences, Irvine, CA, USA) was inserted in three transparent aortic root phantoms with different wall thicknesses (0.55, 0.85 and 1.50 mm) mimicking different physiological distensibilities. Haemodynamic measurements were performed in an in vitro flow loop at heart rates of 60, 80 and 100 bpm with corresponding cardiac outputs of 3.5, 4.0 and 5.0 l/min and aortic pressures of 100/60, 120/90 and 145/110 mmHg, respectively. Aortic valve kinematics were assessed using a high-speed camera. The geometric orifice area (GOA) was measured by counting pixels in the lumen of the open aortic valve. The effective orifice area (EOA) was calculated from the root-mean-square value of the systolic aortic valve flow rate and the mean systolic trans-valvular pressure gradient.

Results

The tested aortic root phantoms reproduce physiological distensibilities of healthy individuals in age groups ranging from 40 to 70 years (±10 years). The haemodynamic results show only minor differences between the aortic root phantoms: the trans-valvular pressure gradient tends to increase for stiffer aortic roots, whereas the systolic aortic valve flow rate remains constant. As a consequence, the EOA decreased slightly for less distensible aortic roots. The GOA and the aortic valve opening and closing velocities increase significantly with reduced distensibility for all haemodynamic measurements. The resulting mean systolic flow velocity in the aortic valve orifice is lower for the stiffer aortic root.

Conclusions

Aortic root distensibility may influence GOA and aortic valve kinematics, which affects the mechanical load on the aortic valve cusps. Whether these changes have a significant effect on the onset of structural valve deterioration of bioprosthetic heart valves needs to be further investigated.

Sex Differences in Phenotypes of Bicuspid Aortic Valve and Aortopathy: Insights From a Large Multicenter, International Registry

BACKGROUND

This large multicenter, international bicuspid aortic valve (BAV) registry aimed to define the sex differences in prevalence, valve morphology, dysfunction (aortic stenosis/regurgitation), aortopathy, and complications (endocarditis and aortic dissection).

METHODS AND RESULTS

Demographic, clinical, and echocardiographic data at first presentation of 1992 patients with BAV (71.5% men) were retrospectively analyzed. BAV morphology and valve function were assessed; aortopathy configuration was defined as isolated dilatation of the sinus of Valsalva or sinotubular junction, isolated dilatation of the ascending aorta distal to the sinotubular junction, or diffuse dilatation of the aortic root and ascending aorta. New cases of endocarditis and aortic dissection were recorded. There were no significant sex differences regarding BAV morphology and frequency of normal valve function. When presenting with moderate/severe aortic valve dysfunction, men had more frequent aortic regurgitation than women (33.8% versus 22.2%, P<0.001), whereas women were more likely to have aortic stenosis (34.5% versus 44.1%, P<0.001). Men had more frequently isolated dilatation of the sinus of Valsalva or sinotubular junction (14.2% versus 6.7%, P<0.001) and diffuse dilatation of the aortic root and ascending aorta (16.2% versus 7.3%, P<0.001) than women. Endocarditis (4.5% versus 2.5%, P=0.037) and aortic dissections (0.5% versus 0%, P<0.001) occurred more frequently in men.

CONCLUSIONS

Although there is a male predominance among patients with BAV, men with BAV had more frequently moderate/severe aortic regurgitation at first presentation compared with women, whereas women presented more often with moderate/severe aortic stenosis compared with men. Furthermore, men had more frequent aortopathy than women.

Collagen analysis of the ascending aortic dilatation associated with bicuspid aortic valve disease compared with tricuspid aortic valve

Dilatation of the ascending aorta is a common occurrence in patients with bicuspid aortic valve (BAV). The aim of the current study was to characterize collagen content in advanced glycation end products (AGEs) of dilated aortic tissue from two distinct areas, concave and convex aortic sites in patients with BAV and TAV. Collagen contents extracted from 100 mg tissue was isolated by enzymatic digestion using pepsin and the nondigested material was further digested using cyanogen bromide, insoluble collagen fraction (ICF) was extracted by hydrochloric acid hydrolysis. BAV tissue showed diminished fluorescence of the pepsin extracted fraction (PEF) compared with TAV tissue (12.4 ± 1.0% vs 32.9 ± 7.6%, p = 0.05). Patients with BAV had PEF of collagens significantly diminished in the dilated ascending aorta, especially in its convex portion, in course of aging and increment of dilated diameters. It is suggestible that BAV patients present more highly AGE-modified collagens in their ascending aorta.

Evaluation of myocardial strain and aortic elasticity in patients with bicuspid aortic valve

This study evaluated the myocardial strain and aortic elasticity in patients with bicuspid aortic valve (BAV) and then investigated the relation between them. Thirty-nine patients (30 males; mean age 44±19 years; range 6 to 75 years) with BAV were recruited as BAV group, and 29 age- and sex-matched healthy controls (21 males; mean age 42±11 years; range 20 to 71 years) served as control group. Aortic strain, distensibility and stiffness index were derived using M-mode echocardiography. Left ventricular global myocardial strain was acquired with speckle-tracking echocardiography. Correlation between aortic elasticity and myocardial strain was also analyzed. The results showed that aortic stiffness was higher (17.5±14.0 vs. 5.3±2.7, P<0.001), and aortic strain (4.9±4.7 vs. 11.0±4.1, P<0.001) and distensibility (1.8±2.1 vs. 3.7±1.6, P<0.001) were lower significantly in BAV group than in control group. Global circumferential strain (-19.1±4.2 vs.-22.5±3.7, P<0.001), radial stain (29.8±14.9 vs. 38.0±8.8, P<0.001) and longitudinal stain (-18.4±3.4 vs.-20.8±3.5, P<0.001) were significantly lower in BAV group than in control group. There was weak association between aortic elasticity and myocardial strain. These findings indicated BAV patients manifest reduced myocardial strain which had weak relationship with aortic elastic lesion.

Noninvasive Imaging of Flow and Vascular Function in Disease of the Aorta

With advancements in technology and a better understanding of human cardiovascular physiology, research as well as clinical care can go beyond dimensional anatomy offered by traditional imaging and investigate aortic functional properties and the impact disease has on this function. Linking the knowledge of the histopathological changes with the alterations in aortic function observed on noninvasive imaging results in a better understanding of disease pathophysiology. Translating this to clinical medicine, these noninvasive imaging assessments of aortic function are proving to be able to diagnose disease, better predict risk, and assess response to therapies. This review is designed to summarize the various hemodynamic measures that can characterize the aorta, the various noninvasive techniques, and applications for various disease states.

The role of cardiovascular magnetic resonance in the assessment of severe aortic stenosis and in post-procedural evaluation following transcatheter aortic valve implantation and surgical aortic valve replacement

Degenerative aortic stenosis (AS) is the most common valvular disease in the western world with a prevalence expected to double within the next 50 years. International guidelines advocate the use of cardiovascular magnetic resonance (CMR) as an investigative tool, both to guide diagnosis and to direct optimal treatment. CMR is the reference standard for quantifying both left and right ventricular volumes and mass, which is essential to assess the impact of AS upon global cardiac function. Given the ability to image any structure in any plane, CMR offers many other diagnostic strengths including full visualisation of valvular morphology, direct planimetry of orifice area, the quantification of stenotic jets and in particular, accurate quantification of valvular regurgitation. In addition, CMR permits reliable and accurate measurements of the aortic root and arch which can be fundamental to appropriate patient management. There is a growing evidence base to indicate tissue characterisation using CMR provides prognostic information, both in asymptomatic AS patients and those undergoing intervention. Furthermore, a number of current clinical trials will likely raise the importance of CMR in routine patient management. This article will focus on the incremental value of CMR in the assessment of severe AS and the insights it offers following valve replacement.

Aortic Arch Stiffness Is Associated With Incipient Brain Injury in Patients With Hypertension

BACKGROUND

It has been shown that microstructural brain tissue damage can be detected in hypertension patients, while the underlying mechanisms are not fully understood. We aim to explore the association between diffusion tensor imaging (DTI) measures of brain injury and aortic arch pulse wave velocity (PWV) in hypertensive patients without clinically manifest cerebrovascular disease.

METHODS

Sixty-six hypertension patients (30 men, mean age 46±14 years) were prospectively included. Aortic arch PWV was assessed using velocity-encoded magnetic resonance imaging (VE-MRI). Brain tissue integrity was assessed by using DTI. Multivariable linear regression analysis was performed to assess the association between aortic arch PWV and fractional anisotropy (FA), axial diffusivity (AxD), and radial diffusivity (RD).

RESULTS

Increased aortic arch PWV was associated with decreased white matter FA (β = -0.30, P = 0.018), increased gray matter AxD (β = 0.28, P = 0.016), and increased gray and white matter RD (β = 0.30, P = 0.008 and β = 0.35, P = 0.003, respectively). These effects were independent of age, sex, body mass index, smoking, and white matter hyperintensity (WMH) volume.

CONCLUSIONS

Aortic arch stiffness relates to incipient brain injury before overt brain abnormalities may become apparent in patients with hypertension.

Local Application of Leptin Antagonist Attenuates Angiotensin II-Induced Ascending Aortic Aneurysm and Cardiac Remodeling

Background

Ascending thoracic aortic aneurysm (ATAA) is driven by angiotensin II (AngII) and contributes to the development of left ventricular (LV) remodeling through aortoventricular coupling. We previously showed that locally available leptin augments AngII‐induced abdominal aortic aneurysms in apolipoprotein E–deficient mice. We hypothesized that locally synthesized leptin mediates AngII‐induced ATAA.

Methods and Results

Following demonstration of leptin synthesis in samples of human ATAA associated with different etiologies, we modeled in situ leptin expression in apolipoprotein E–deficient mice by applying exogenous leptin on the surface of the ascending aorta. This treatment resulted in local aortic stiffening and dilation, LV hypertrophy, and thickening of aortic/mitral valve leaflets. Similar results were obtained in an AngII‐infusion ATAA mouse model. To test the dependence of AngII‐induced aortic and LV remodeling on leptin activity, a leptin antagonist was applied to the ascending aorta in AngII‐infused mice. Locally applied single low‐dose leptin antagonist moderated AngII‐induced ascending aortic dilation and protected mice from ATAA rupture. Furthermore, LV hypertrophy was attenuated and thickening of aortic valve leaflets was moderated. Last, analysis of human aortic valve stenosis leaflets revealed de novo leptin synthesis, whereas exogenous leptin stimulated proliferation and promoted mineralization of human valve interstitial cells in culture.

Conclusions

AngII‐induced ATAA is mediated by locally synthesized leptin. Aortoventricular hemodynamic coupling drives LV hypertrophy and promotes early aortic valve lesions, possibly mediated by valvular in situ leptin synthesis. Clinical implementation of local leptin antagonist therapy may attenuate AngII‐induced ATAA and moderate related LV hypertrophy and pre–aortic valve stenosis lesions.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00449306.

How to estimate aortic characteristic impedance from magnetic resonance and applanation tonometry data?

OBJECTIVES

Compare seven previous methods for the estimation of aortic characteristic impedance, which contributes to left ventricle pulsatile load, from phase-contrast cardiovascular magnetic resonance (CMR) and applanation tonometry data.

METHODS

We studied 77 healthy (43 ± 16 years) individuals and 16 hypertensive (61 ± 9 years) patients, who consecutively underwent ascending aorta CMR and carotid tonometry, resulting in flow and pressure waveforms, respectively. Characteristic impedance was semi-automatically estimated in time domain from these latter waveforms, using seven methods. The methods were based on the following: methods 1-4, magnitudes at specific times; method 5, early-systolic up-slope; method 6, time-derivatives peak; and method 7, pressure-flow loop early-systolic slope.

RESULTS

Aortic characteristic impedance was significantly increased in hypertensive patients when compared to elderly controls (n = 32) with a similar mean age of (59 ± 8 years) when using methods based on 95% of peak flow, up-slopes, and derivatives peaks (P < 0.05). When considering healthy individuals, impedance indices were significantly correlated to central pulse pressure for all methods (P < 0.005). Finally, characteristic impedance was correlated to the frequency-domain reference values (r > 0.65, P < 0.0001), with a slight superiority for the same three methods as above (r > 0.82, P < 0.0001).

CONCLUSIONS

This is the first study demonstrating phase-contrast CMR and tonometry usefulness in aortic characteristic impedance temporal estimation. Methods based on 95% of peak flow, as well as those based on derivative peaks and up-slopes, which are fast and independent of curve preprocessing, were slightly superior. They can be easily integrated in a clinical workflow and may help to understand the complementarity of this pulsatile index with other CMR aortic geometry and stiffness measures in the setting of left ventricle-aortic coupling.

Intima-media thickness of the descending aorta in patients with bicuspid aortic valve

Objective

A bicuspid aortic valve (BAV) is associated with accelerated aortic valve disease (AVD) and abnormalities in aortic elasticity. We investigated the intima-media thickness of the descending aorta (AoIMT) in patients with AVD with or without an ascending aortic aneurysm (AscAA), in relation to BAV versus tricuspid aortic valve (TAV) phenotype, type of valve disease, cardiovascular risk factors, and single-nucleotide polymorphisms (SNPs) with a known association with carotid IMT.

Methods and results

368 patients (210 with BAV, 158 with TAV,); mean age 64 ± 13 years) were examined using transesophageal echocardiography (TEE) before valvular and/or aortic surgery. No patient had a coronary disease (CAD). The AoIMT was measured on short-axis TEE images of the descending aorta using a semi-automated edge-detection technique. AoIMT was univariately (P < 0.05) related to age, blood pressure, smoking, creatinine, highly sensitive C-reactive protein, HDL, valve hemodynamics and BAV. In the TAV subgroup it was also associated with the rs200991 SNP. Using multivariate regression analysis, age was the main determinant for AoIMT (P < 0.001), followed by male gender (P = 0.02), BAV was no longer a significant predictor of AoIMT. AoIMT was still related to the rs200991 SNP in TAV (P = 0.034), and to creatinine in BAV (P = 0.019), when other variables were accounted for.

Conclusions

Intima-media thickness of the descending aorta is not affected by aortic valve morphology (BAV/TAV); age is the main determinant of AoIMT. Genetic markers (SNPs) known to influence IMT in the carotid artery seem to correlate to IMT in the descending aorta only in patients with TAV.

Evaluation of Cardiovascular Changes in Children with BAVs

The objectives of this study were to investigate left ventricular (LV) function, aortic dilation, and atherosclerosis in children with mildly deteriorated isolated bicuspid aortic valve (BAV) function using echocardiographic studies and biochemical markers of atherosclerosis and to correlate results with normal children. Biochemical analyses indicating cardiovascular risk of atherosclerosis and vascular changes in the aorta in relation to BAV were performed in 41 children aged 5-15 years old with isolated BAV and in 25 children with tricuspid aortic valves. Evaluations of aortic valve structures and functions; examinations of the LV M-mode and ascending aorta Doppler; and measurements of the LV Tei index (MPI), propagation velocity, ascending aorta at four levels, and carotid intima-media thickness (CIMT) were performed. There were no statistically significant differences in CIMTs, plasma matrix metalloproteinase-9, tissue metalloproteinase inhibitor-1 levels, or other biochemical parameters indicating cardiovascular risk or atherosclerosis between study and control groups. Deterioration of LV function, which could not be seen with M-mode echocardiography, was evident by MPI. MPI values in the study versus control groups were 0.46 ± 0.080 versus 0.40 ± 0.086 (p < 0.05). Diameters of the aorta in the study and control groups were 19.7 ± 4.7 and 17.2 ± 2.8 mm (p < 0.05) at the sinotubular junction level and 20.6 (14.4-40.5) and 18.3 (12.4-24) mm at the ascending aorta level (p < 0.05). Increased aortic valve insufficiency was related to increased aortic diameter. No sign of atherosclerosis was detected in children with BAV. Deterioration of LV function was seen using MPI, and aortic dilation was related to the severity of aortic valve insufficiency.

Association of aortic phenotypes and mechanical function with left ventricular diastolic function in subjects with normally functioning bicuspid aortic valves and comparison to subjects with tricuspid aortic valves

A bicuspid aortic valve (BAV) is often associated with dilation or aneurysm of the ascending aorta (AA) despite of absence of significant valve dysfunction. Bicuspid aortopathy and consequent aortic stiffness may adversely affect left ventricular (LV) diastolic function. This study aimed to investigate the impact of global and regional aortic mechanical function on LV diastolic function in subjects with BAV. Fifty-six subjects with BAV (45 men, mean age 52 ± 13 years) without significant valve dysfunction and 56 age- and gender-matched controls with tricuspid aortic valve were studied. The aortic phenotypes were classified into 3 groups: normal shape, predominant dilatation of the sinus of Valsalva, and predominant dilatation of the AA. Structural and functional parameters of the AA and LV were measured using 2-dimensional echocardiography. Global aortic mechanical function was assessed by radial artery tonometry. The subjects with BAV showed a higher incidence of a predominant AA phenotype (53.6% vs 17.9%, p <0.001), larger indexed aortic diameters, increased augmentation index, lower pulse pressure amplification, lower early diastolic mitral annular (e') velocity, and higher E/e' than those with tricuspid aortic valve . The e' velocity and E/e' varied with different aortic phenotypes in subjects with BAV. Correlations between e' velocity and parameters of aortic stiffness were stronger in subjects with BAV than those in controls. Multiple regression analysis revealed that augmentation index normalized for a heart rate of 75 beats/min was an independent determinant of e' velocity (β = -0.24, p = 0.044) and E/e' (β = 0.30, p = 0.018) in subjects with BAV even after controlling for confounding factors. LV diastolic function is closely related to aortic phenotype and mechanical alteration in subjects with BAV.

Effect of personalized external aortic root support on aortic root motion and distension in Marfan syndrome patients

OBJECTIVE

Personalized external aortic root support (PEARS) is a novel surgical approach with the aim of stabilizing the aortic root size and decreasing risk of dissection in Marfan syndrome patients. A bespoke polymer mesh tailored to each patient's individual aorta shape is produced by modeling and then surgically implanted. The aim of this study is to assess the mechanical effects of PEARS on the aortic root systolic downward motion (an important determinant of aortic wall stress), aortic root distension and on the left ventricle (LV).

METHODS/RESULTS

A cohort of 27 Marfan patients had a prophylactic PEARS surgery between 2004 and 2012 with 24 having preoperative and follow-up cardiovascular magnetic resonance imaging studies. Systolic downward aortic root motion, aortic root distension, LV volumes/mass and mitral annular systolic excursion before the operation and in the latest follow-up were measured randomly and blinded. After a median follow-up of 50.5 (IQR 25.5-72) months following implantation of PEARS, systolic downward motion of aortic root was significantly decreased (12.6±3.6mm pre-operation vs 7.9±2.9mm latest follow-up, p<0.00001). There was a tendency for a decrease in systolic aortic root distension but this was not significant (median 4.5% vs 2%, p=0.35). There was no significant change in LV volumes, ejection fraction, mass and mitral annular systolic excursion in follow-up.

CONCLUSIONS

PEARS surgery decreases systolic downward aortic root motion which is an important determinant of longitudinal aortic wall stress. Aortic wall distension and Windkessel function are not significantly impaired in the follow-up after implantation of the mesh which is also supported by the lack of deterioration of LV volumes or mass.

Use and limitations of cardiac magnetic resonance derived measures of aortic stiffness in patients after acute myocardial infarction

INTRODUCTION

Cardiac magnetic resonance (CMR) is a unique method to determine regional and local aortic stiffness parameters. Although various methods have been validated, there are no data in patients after acute ST-segment elevation myocardial infarction (STEMI). In the present study we assessed the feasibility of different CMR derived measures of aortic stiffness in patients after first acute STEMI for the first time.

METHODS

CMR derived aortic pulse wave velocity (PWV) determined by the regional transit-time (PWVTT) and local flow-area (PWVQA) method as well as local distensibility coefficients (DCs) was analyzed in 22 healthy young volunteers and 28 patients with recent acute STEMI.

RESULTS

PWVTT and DC of the ascending aorta differed significantly between healthy subjects and STEMI patients (all p<0.001). PWVQA at thoracic levels of aorta was not different between groups (p>0.520) and did not correlate with age (p>0.149) and PWVTT (p>0.310). Intra- and interobserver variability was high for PWVTT (r=0.970, p<0.001 and r=0.920, p<0.001), acceptable for DC (all r>0. 809, p<0.001 and all r>0.510, p<0.001) but low for thoracic PWVQA (all r<0.330 and all r<0.372).

CONCLUSION

PWVTT and local DC are robust methods for the assessment of aortic stiffness in patients after acute STEMI.

Aortic dilatation and aortopathies in congenital heart disease

PURPOSE OF REVIEW

The objective of this review is to summarize the recent data pertaining to aortic dilatation in congenital heart disease (CHD) and to discuss the current understanding of the pathophysiology and management of this disease.

RECENT FINDINGS

Aortic dilatation is a common finding in CHD. However, acute aortic complications appear to be relatively rare. Multiple factors predispose this population to aortic dilatation, including underlying genetics, cellular-based mechanisms, and abnormalities in aortic mechanics and valve morphology.

SUMMARY

Although aortic dilatation is common in CHD, data about adverse long-term outcomes are limited. Optimal disease-specific management strategies have yet to be developed, and further research is needed to guide care in this population.