Aortic Compliance Research Articles

Morphotype-Dependent Flow Characteristics in Bicuspid Aortic Valve Ascending Aortas: A Benchtop Particle Image Velocimetry Study.

The bicuspid aortic valve (BAV) is a major risk factor for secondary aortopathy such as aortic dilation. The heterogeneous BAV morphotypes [left-right-coronary cusp fusion (LR), right-non-coronary cusp fusion (RN), and left-non-coronary cusp fusion (LN)] are associated with different dilation patterns, suggesting a role for hemodynamics in BAV aortopathogenesis. However, assessment of this theory is still hampered by the limited knowledge of the hemodynamic abnormalities generated by the distinct BAV morphotypes. The objective of this study was to compare experimentally the hemodynamics of a normal (i.e., non-dilated) ascending aorta (AA) subjected to tricuspid aortic valve (TAV), LR-BAV, RN-BAV, and NL-BAV flow. Tissue BAVs reconstructed from porcine TAVs were subjected to physiologic pulsatile flow conditions in a left-heart simulator featuring a realistic aortic root and compliant aorta. Phase-locked particle image velocimetry experiments were carried out to characterize the flow in the aortic root and in the tubular AA in terms of jet skewness and displacement, as well as mean velocity, viscous shear stress and Reynolds shear stress fields. While all three BAVs generated skewed and asymmetrical orifice jets (up to 1.7- and 4.0-fold increase in flow angle and displacement, respectively, relative to the TAV at the sinotubular junction), the RN-BAV jet was out of the plane of observation. The LR- and NL-BAV exhibited a 71% increase in peak-systolic orifice jet velocity relative to the TAV, suggesting an inherent degree of stenosis in BAVs. While these two BAV morphotypes subjected the convexity of the aortic wall to viscous shear stress overloads (1.7-fold increase in maximum peak-systolic viscous shear stress relative to the TAV-AA), the affected sites were morphotype-dependent (LR-BAV: proximal AA, NL-BAV: distal AA). Lastly, the LR- and NL-BAV generated high degrees of turbulence in the AA (up to 2.3-fold increase in peak-systolic Reynolds shear stress relative to the TAV) that were sustained from peak systole throughout the deceleration phase. This in vitro study reveals substantial flow abnormalities (increased jet skewness, asymmetry, jet velocity, turbulence, and shear stress overloads) in non-dilated BAV aortas, which differ from those observed in dilated aortas but still coincide with aortic wall regions prone to dilation.

Relation Between LV Diastolic Function and Aortic Compliance as Assessed by Transthoracic Echo

Arterial compliance and stiffness of the ascending aorta are important components of the elastic nature of the arterial system. Several pathological conditions are known to potentially affect arterial compliance properties as occurs with the arterial hypertension, and diabetes mellitus. Factors known to affect LV elasticity are similar to those affecting aortic elasticity. Our aim in that study is to study correlation of aortic stiffness and LV diastolic function and the factors that affect each. We scanned 254 patients presenting for routine echocardiography to Ain Shams University Hospitals Echocardiography unit; where clinical history was taken, examination and 2D echocardiography done where we indexed the elastic properties of the aorta by calculating of aortic distensibility (AD), aortic stiffness index (ASI), and pressure-strain elastic modulus (Ep), and LV diastolic function was evaluated as well. Both presence and grade of left ventricular diastolic dysfunction were significantly correlated with each of arterial hypertension and diabetes mellitus separately and presence of both hypertension and diabetes mellitus was correlated with LVDD. Aortic compliance-with its three studied elements; AS%, AD and ASI-was significantly correlated with grade of LVDD yet only elastic modulus was independently correlated with diastolic dysfunction.

Sarcopenia and vascular risk in a healthy elderly UK population (BRAVES Study)

Introduction Sarcopenia, the loss of skeletal muscle mass and strength that occurs with advancing age [1] is correlated with functional decline and disability but little is known about its relationship with cardiovascular risk. Bioimpedence analysis (BIA) is a validated technique for measuring muscle mass, convenient for use in large cohort studies. Arterial stiffness (compliance) is an independent predictor of cardiovascular events. Methods The BRAVES study was designed to compare cardiovascular risk between two healthy elderly cohorts in the UK and in Italy. We used data from the UK cohort to investigate the relationship between sarcopenia and vascular compliance. Participants were eligible if aged 65-85 years, lived within the Brighton area and had weight loss of no more than 5% in the last month. All underwent physical exam, BIA assessment of skeletal mass index (SMI) and two measures of arterial compliance. Pulse wave velocity (PWV) was measured between carotid-femoral and carotid-radial arteries and the augmentation index (AIx) derived from carotid and radial arteries. A bivariate correlation was performed. Results Ninety patients (64 female; 26 male) had mean age 73, mean FFM 46.84kg (range 34.7-74.7) and mean SMI 6.77 (range 4.84-10.09). There was a negative relationship between SMI and Radial AIx (R=0.-542, p=0.000) as well as Carotid AIx (R=-0.391, p=0.002) but not PWV. Using multiple regression to control for the effects of age and gender, SMI was independently related to radial AIx (p=.013). Conclusions Skeletal muscle mass index is strongly negatively correlated with augmentation index, a measure of vascular stiffness. This finding suggests that elderly patients with higher muscle mass have a more compliant aorta and hence lower cardiovascular risk. Whether sarcopenia acts as a marker for CV risk or plays an active role in cardiovascular disease progression is not yet established and deserves further investigation.

Aortic compliance variation in long male distance triathletes: A new insight into the athlete's artery?

To assess cardiac and vascular adaptations in long-distance male triathletes and the influence of an increased training volume on these parameters. Case-control study using long-distance male triathletes (Tri) (n=12) and an age-matched cohort of sedentary volunteers (Ctrl). All participants gave an informed consent and underwent a Cardiovascular Magnetic Resonance imaging (CMR) exam to measure left and right ventricle functional parameters, and aortic parameters (surface, strain, compliance, pulse wave velocity). This exam was repeated in the triathletes' group after an increased training volume of at least 2h/week for six weeks. Compared to control volunteers, triathletes presented at baseline a typical pattern of athlete's heart (higher end-diastolic, end-systolic and stroke volumes index, p≤0.009, and lower cardiac rate, p=0.015) but similar vascular characteristics except a trend towards an enlarged ascending aorta (surface 942±106 vs 812±127mm2, p=0.058). Between the two visits, the triathletes increased their weekly training time from 9.67±2.43 (Tri1) to 12.15±3.01h (Tri2): no modifications were found regarding cardiac parameters, but compliance and distensibility of the ascending aorta increased, from 2.60 to 3.34mm2/mmHg (p=0.028) and from 3.36 to 4.40×10-3mmHg-1 (p=0.048) respectively. Using CMR, we showed that vascular characteristics of the ascending aorta may vary along the sport season in endurance athletes. This remodelling could be considered as a physiological adaptation, but could eventually lead to an adverse vascular remodelling.

New estimate of valvuloarterial impedance in aortic valve stenosis: A cardiac magnetic resonance study.

Valvuloarterial impedance (ZVA ), estimating left ventricle (LV) afterload, has been proposed in transthoracic echocardiography (TTE) as a predictor of mortality in aortic valve stenosis (AVS). However, its calculation differs from arterial characteristic impedance (ZC ). Our aim was to apply the concept of ZC calculation to estimate ZVA from MR with carotid tonometry and to evaluate these indices through their associations with symptoms, LV diastolic function and aortic stiffness. In 40 patients with AVS (76 ± 13 years), ZVA-TI derived from velocity time integral and E/Ea were estimated by TTE. ZVA-INS , based on ZC formula, calculated as the instantaneous pressure gradient to peak flow ratio and aortic compliance were estimated by using MRI at 1.5 Tesla. Both ZVA estimates were higher in symptomatic than asymptomatic patients (707 ± 22 versus 579 ± 53 dyne.s/cm5 , P = 0.031 for ZVA-INS and 4.35 ± 0.16 versus 3.33 ± 0.38 mmHg.m2 /mL, P = 0.018 for ZVA-TI ). Although they were both associated with aortic compliance (r = -0.45; P = 0.006 for ZVA-INS and r = -0.43; P = 0.008 for ZVA-TI ) only ZVA-INS was associated with E/Ea (r = 0.50; P < 0.001). In multivariate analysis to identify determinants of E/Ea, a model including age, mean blood pressure, LV ejection fraction, LV mass, and aortic valve area was performed (R2 = 0.41; P < 0.01). When ZVA-INS was added to the model, its overall significance was higher R2 = 0.56 (P < 0.01) and ZVA-INS and LV mass were the only significant determinants. ZVA-INS was more strongly associated with diastolic dysfunction than usual parameters quantifying AVS severity. This new ZVA estimate could improve LV afterload evaluation. 1 J. Magn. Reson. Imaging 2017;45:795-803.

Developmental Changes in Aortic Mechanical Properties in Normal Fetuses and Fetuses with Cardiovascular Disease

We hypothesized that fetal aortic mechanical properties assessed by aortic diameter (AoD) and flow show maturational changes during the gestational period, and that these properties are different in fetuses with congenital heart diseases and fetuses with normal development. Phasic changes in ascending AoD along with Doppler flow profile were measured in 84 consecutive normal fetuses (gestational age, 18-36weeks) and in 30 consecutive fetuses with cardiovascular diseases (gestational age, 22-39weeks). AoD and cardiac output significantly increased with gestational age. Fetal aortic compliance (AC), assessed as (maximum AoD - minimum AoD)/stroke volume, significantly decreased with gestational age in normal fetuses, indicating maturational changes in aortic wall properties. Importantly, fetuses with Marfan syndrome and tetralogy of Fallot that exhibit "aortopathy" showed significantly lower AC than normal fetuses of the same gestational age, suggesting intrinsic abnormalities in aortic wall properties in these diseases. Fetuses with trisomy 18 and Noonan syndrome also had AC values below the normal ranges. Measurements of phasic changes in fetal AoD and flow measurements can provide useful information about aortic mechanical properties and may help clarify abnormal arterial hemodynamics in pathologic conditions.

OP.5B.07] DIASTOLIC EXPONENTIAL DECAY OF CENTRAL BLOOD PRESSURE MEDIATES BETWEEN AORTIC STIFFNESS AND CORONARY PERFUSION

Objective: Stiffening of the aorta often precedes coronary events in hypertension. However, little is known about the etiological mechanism by which aortic stiffening causes myocardial ischemia. Hemodynamic research suggests that most of coronary flow occurs during diastole, depending on lateral pressure in the central aorta. We hypothesized that predisposition to myocardial ischemia is attributable to aortosclerosis-induced alterations in central diastolic pressure. Design and method: The study group comprised 222 patients with uncomplicated hypertension. Tonometric signals were recorded to estimate the aortic waveform from the radial waveform and to measure the carotid-femoral (aortic) and femoral-pedis (peripheral) pulse wave velocities (PWVs). Aortic compliance was computed from aortic characteristic impedance and PWV. The least-squares method was used to fit a monoexponential curve to aortic pressure decay during diastole as P(t) = P0*exp(-λ*t) [λ: decay index; P0: end-systolic pressure; t: time from end-systole]. Myocardial perfusion was quantified using the subendocardial viability index (SVI), calculated as the central diastolic/systolic pressure-time integral ratio. Results: The central diastolic pressure decay fit closely to an exponential curve for all patients (R2 = 0.98 ± 0.02). The median (interquartile range) of decay index was 0.59 (0.49–0.70) per second. The decay index was significantly (P < 0.001) correlated with aortic PWV (r = 0.53) and compliance (r = -0.65), but not with peripheral PWV or total peripheral resistance. The relationships of aortic PWV and compliance with decay index remained significant after controlling for age, gender, renal function, diabetes and end-systolic pressure (P < 0.001). Both aortic PWV and compliance were also associated with SVI (r = -0.39 and r = 0.37, P < 0.001); however, these associations were no longer significant after accounting for decay index. Mediation analysis revealed that 75% of the association between aortic PWV and SVI was mediated by decay index. A similar mediating effect of decay index was observed for the association between aortic compliance and SVI. In contrast, aortic augmentation index did not constitute a mediator of these associations. Conclusions: Our results suggest that associations between aortic stiffness and subendocardial viability are mediated through diastolic exponential decay (rather than late-systolic augmentation) of central pressure. Aortic stiffening potentially reduces myocardial perfusion by accelerating diastolic pressure decay, thus predisposing to ischemic heart disease.

LBPS 02-01 ASCENDING AORTA ELASTICITY AND RELATED RISK FACTORS STUDY ON EARLY STAGE HYPERTENSION PATIENTS

Objective: to discuss the characteristic of ascending aorta elasticity derived from coronary CTA for specific early stage hypertension patients and its risk factors Design and method: 398 participants underwent coronary CTA examinations using a 128 slicer CT scanner. Images were automatically reconstructed at every 5% absolute phases in the entire R-R interval. The differences of three vascular elasticity indices including aortic distensibility (AD), aortic compliance (AC) and aortic stiffness (ASI) were analyzed among the normal blood pressure, early stage hypertension and primary hypertension groups Results: Normalized cross-sectional area for the ascending aorta was found significant lower in early stage hypertension group than that of primary hypertension group, but no difference was seen for normalized diameter. Also, no significant difference was found for and between early stage hypertension group and normal group. AD, AC and ASI were significantly different in three comparison groups. Pair-wise study indicated that between early stage hypertension and normal groups, AD and AC were found much smaller but no difference were found for ASI; while between early stage hypertension and primary hypertension groups, AD and ASI were found significantly different but not for AC. Risk factor study for early stage hypertension patients indicated that AD was significant different between smoking and non-smoking groups. Linear correlation coefficient between AD and age, Ps, dp, and glycosylated hemoglobin were −0.69 (P < 0.001), −0.37 (P < 0.001), −0.43 (P < 0.001) and −0.43 (P < 0.05) respectively. Age and Ps were the independent risk factors for AD decline. Conclusions: It is proofed that the early detection of aortic elasticity index changes, especially for AD and its risk factors, are essential for identifying the high risk individuals in the early stage hypertension populations

Impact of Decreased Serum Insulin-Like Growth Factor-1 Levels on Central Aortic Compliance in Small-for-Gestational-Age Infants

Background: Intrauterine growth restriction is associated with arterial hypertension in adulthood; however, the underlying mechanism is unclear. Objectives: We hypothesized that serum insulin-like growth factor-1 (IGF-1) levels affect central aortic elastic properties and structure in small-for-gestational-age (SGA) infants. Methods: Eighteen SGA infants and 22 appropriate-for-gestational-age (AGA) infants were enrolled in this study. The serum IGF-1 level within 1 h of birth and abdominal aortic echo parameters at 1 week of age were retrospectively compared. Results: In the SGA infants, IGF-1 levels (27.6 ± 17.7 vs. 42.6 ± 15 ng/ml, p = 0.006), aortic strain (10.2 ± 3.1 vs. 12.8 ± 3.1%, p = 0.01), and aortic distensibility (0.73 ± 0.19 vs. 0.92 ± 0.34 cm²/dyn × 10^-4, p = 0.05) were significantly lower compared with AGA infants. By contrast, blood pressure, aortic intima-media thickness (aIMT) in relation to body weight (383 ± 163 vs. 256 ± 43 μm/kg, p < 0.001), aortic stiffness index in relation to body weight (2.0 ± 1.7 vs. 1.1 ± 0.4, p = 0.005), and arterial pressure-strain elastic modulus (293 ± 72 vs. 242 ± 78 mm Hg, p = 0.04) were higher compared with AGA infants. In the SGA infants, IGF-1 levels were significantly correlated with aortic strain (r = 0.49, p = 0.04), aIMT in relation to body weight (r = -0.61, p = 0.007), and aortic stiffness index in relation to body weight (r = -0.63, p = 0.005). Conclusions: Decreased serum IGF-1 levels in SGA infants may affect the vascular compliance and structure of the central aorta.

Chronic environmental warming alters cardiovascular and haematological stress responses in European perch (Perca fluviatilis).

Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals like fish. While thermal acclimation can buffer the direct thermal effects on basal cardiorespiratory function during chronic warming, little is known about how acclimation affects stress-induced cardiorespiratory responses. We compared cardiovascular and haematological responses to chasing stress in cannulated wild European perch (Perca fluviatilis) from a reference area at natural temperature (16°C) with perch from the 'Biotest enclosure'; an experimental system chronically warmed (22°C) by effluents from a nuclear power plant. Routine blood pressure was similar, but Biotest perch had slightly higher resting heart rate (59.9±2.8 vs 51.3±2.9beatsmin-1), although the Q 10 for heart rate was 1.3, indicating pronounced thermal compensation. Chasing stress caused hypertension and a delayed tachycardia in both groups, but the maximum heart rate increase was 2.5-fold greater in Biotest fish (43.3±4.3 vs 16.9±2.7beatsmin-1). Moreover, the pulse pressure response after stress was greater in reference fish, possibly due to the less pronounced tachycardia or a greater ventricular pressure generating capacity and thermally mediated differences in aortic compliance. Baseline haematological status was also similar, but after chasing stress, the haematocrit was higher in Biotest fish due to exacerbated red blood cell swelling. This study highlights that while eurythermal fishes can greatly compensate routine cardiorespiratory functions through acclimation processes, stress-induced responses may still differ markedly. This knowledge is essential when utilising cardiorespiratory variables to quantify and compare stress responses across environmental temperatures, and to forecast energetic costs and physiological constraints in ectothermic animals under global warming.

Aortic Function's Adaptation in Response to Exercise-Induced Stress Assessing by 1.5T MRI: A Pilot Study in Healthy Volunteers.

AimEvaluation of the aortic “elastic reserve” might be a relevant marker to assess the risk of aortic event. Our aim was to compare regional aortic elasticity at rest and during supine bicycle exercise at 1.5 T MRI in healthy individuals.MethodsFifteen volunteers (8 men), with a mean age of 29 (23–41) years, completed the entire protocol. Images were acquired immediately following maximal exercise. Retrospective cine sequences were acquired to assess compliance, distensibility, maximum rates of systolic distension and diastolic recoil at four different locations: ascending aorta, proximal descending aorta, distal descending aorta and aorta above the coeliac trunk level. Segmental aortic pulse wave velocity (PWV) was assessed by through plane velocity-encoded MRI.ResultsExercise induced a significant decrease of aortic compliance and distensibility, and a significant increase of the absolute values of maximum rates of systolic distension and diastolic recoil at all sites (p<10–3). At rest and during stress, ascending aortic compliance was statistically higher compared to the whole descending aorta (p≤0.0007). We found a strong correlation between the rate pressure product and aortic distensibility at all sites (r = - 0.6 to -0.75 according to the site, p<10–4). PWV measured at the proximal and distal descending aorta increased significantly during stress (p = 0.02 and p = 0.008, respectively).ConclusionAssessment of regional aortic function during exercise is feasible using MRI. During stress, aortic elasticity decreases significantly in correlation with an increase of the PWV. Further studies are required to create thresholds for ascending aorta dysfunction among patients with aneurysms, and to monitor the impact of medication on aortic remodeling.

Influence of the central-to-peripheral arterial stiffness gradient on the timing and amplitude of wave reflections.

In individuals with compliant aortas, peripheral muscular artery stiffness exceeds central elastic artery stiffness. With aging, central stiffness increases with little change in peripheral stiffness, resulting in a reversal of the normal stiffness gradient. This reversal may reduce the wave reflection amplitude due to the movement of the major 'effective' reflection site further from the heart. To test this phenomenon, we investigated the relationship among arterial stiffness gradients (normal and reversed), wave reflection amplitude and reflection site distance. Subjects aged ⩾50 years were recruited from the Anglo-Cardiff Collaborative Trial. Central stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV). In Study 1, peripheral PWV was also measured in the arm (carotid-radial pulse wave velocity) and, in Study 2, in the leg (femoral-dorsalis pedis). Reflection site distance was calculated from cfPWV and the reflected wave Tr. Subjects were dichotomized into those with a normal stiffness gradient (peripheral >central PWV) or a reversed gradient (peripheral <central PWV). In Study 1, the reflection site distance was greater in subjects with a reversed gradient (P<0.01), whereas time-to-reflection was lower (P<0.001). Both the augmentation pressure (P<0.001) and augmentation index (P<0.05) were greater in subjects with a reversed gradient. In Study 2, the augmentation pressure, augmentation index and reflection site distance were greater in subjects with a reversed stiffness gradient (P<0.01, P<0.05 and P<0.01, respectively), and time-to-reflection was not different between groups. A reversed arterial stiffness gradient is associated with an increased reflection site distance, and a paradoxical increase in reflected wave amplitude and augmentation index.

Modulation of the sympathetic nervous system by renal denervation prevents reduction of aortic distensibility in atherosclerosis prone ApoE-deficient rats.

BackgroundApolipoprotein E-deficient (ApoE−/−) rodents spontaneously develop severe hypercholesterolemia and increased aortic stiffness, both accepted risk factors for cardiovascular morbidity and mortality in humans. In patients with resistant hypertension renal denervation (RDN) may improve arterial stiffness, however the underlying mechanisms are incompletely understood. This study investigates the impact of RDN on aortic compliance in a novel atherosclerosis prone ApoE−/−-rat model.MethodsNormotensive, 8 weeks old ApoE−/− and Sprague–Dawley (SD) rats were subjected to bilateral surgical RDN (n = 6 per group) or sham operation (n = 5 per group) and fed with normal chow for 8 weeks. Compliance of the ascending aorta was assessed by magnetic resonance imaging. Vasomotor function was measured by aortic ring tension recordings. Aortic collagen content was quantified histologically and plasma aldosterone levels were measured by enzyme-linked immunosorbent assay (ELISA).ResultsAfter 8 weeks, ApoE−/−-sham demonstrated a 58 % decrease in aortic distensibility when compared with SD-sham (0.0051 ± 0.0011 vs. 0.0126 ± 0.0023 1/mmHg; p = 0.02). This was accompanied by an impaired endothelium-dependent relaxation of aortic rings and an increase in aortic medial fibrosis (17.87 ± 1.4 vs. 12.27 ± 1.1 %; p = 0.006). In ApoE−/−-rats, RDN prevented the reduction of aortic distensibility (0.0128 ± 0.002 vs. 0.0051 ± 0.0011 1/mmHg; p = 0.01), attenuated endothelial dysfunction, and decreased aortic medial collagen content (12.71 ± 1.3 vs. 17.87 ± 1.4 %; p = 0.01) as well as plasma aldosterone levels (136.33 ± 6.6 vs. 75.52 ± 8.4 pg/ml; p = 0.0003). Cardiac function and metabolic parameters such as hypercholesterolemia were not influenced by RDN.ConclusionApoE−/−-rats spontaneously develop impaired vascular compliance. RDN improves aortic distensibility and attenuated endothelial dysfunction in ApoE−/−-rats. This was associated with a reduction in aortic fibrosis formation, and plasma aldosterone levels.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0914-9) contains supplementary material, which is available to authorized users.

Assessment of relation between aortic elastic properties and the complexity of coronary artery disease

Objectives The aim of this study was to evaluate whether there is an independent association between impaired aortic elasticity properties and the complexity of coronary artery disease (CAD) using the SYNTAX score (SS).Methods Three hundred sixty-seven patients (male 64.9%) aged 31 to 89 years (average age 62.07 years) with CAD who underwent coronary angiography were enrolled in this study. Patients with a SS ≤ 17 (n = 211; male 66.8%) were classified as the low SS group (Low-SSG), from 18 to 28 (n = 108; male 61.1%) were classified as the intermediate SS group (In-SSG), and ≥ 29 (n = 44; male 64.6%) classified as the high SS group (High-SSG). In all groups, aortic elastic properties were obtained from hospital records. These properties, including aortic diameter change (AoDC), aortic stiffness (AoS), aortic stiffness index- β(AoSI-β), aortic distensibility (AoD), aortic Petersen’s elastic modulus (AoEp), aortic compliance (AoCI) and the compliance to distensibility ratio (AoCDR), were compared.Results AoS was significantly lower in High-SSG than in Low-SS and In-SSG, (P =0.004). However, the AoEp in High-SSG was significantly higher than in Low-SSG and In-SSG, (P =0.012). A negative correlation was detected between the SS and each of AoDC, AoS, AoD, AoCI and AoCDR. A positive correlation was detected between the SS and AoSI- βand AoEp in the patients with CAD.Conclusion This study demonstrated that aortic elastic properties are more impaired in patients with severe and complex CAD. There is an independent relationship between reduced aortic elasticity and the severity and complexity of CAD.

010 Insights into hypertensive heart disease phenotypes: Spectrum of myocyte, interstitial and vascular changes by cardiovascular MRI

Introduction Hypertensive heart disease (HHD) can be classified into 4 left ventricular (LV) phenotypes: 1) normal, 2) concentric LV remodelling (LVr), 3) concentric LV hypertrophy (cLVH) and 4) eccentric LV hypertrophy (eLVH). The pathophysiology of the phenotypes is incompletely understood. We investigate extent of myocardial interstitial fibrosis and aortic impairment in HHD with cardiovascular magnetic resonance (CMR) Methods 88 hypertensives (49 ± 14yrs, 57% male, SBP: 167 ± 30mmHg, DBP: 96 ± 14mmHg) underwent CMR (1.5T) and were compared with 29 age- and sex-matched normotensive controls (47 ± 14years, 59% male, SBP: 128 ± 12mmHg, DBP: 79 ± 10mmHg). Native T1 and extra-cellular volume fraction were measured. Circumferential myocardial strain was calculated by voxel-tracking. Aortic compliance was recorded. Results At a structural level, increased LV mass in eccentric and concentric LVH resulted from: i) significantly increased myocardial cell volume (eLVH: 78 ± 19g/m 2 vs cLVH: 73 ± 15g/m 2 vs LVr: 55 ± 9g/m 2 respectively, P 2 vs cLVH: 30 ± 10g/m 2 vs LVr: 19 ± 2g/m 2 respectively, P Conclusion Myocardial interstitial fibrosis is varies across HHD phenotypes with functional consequences. Eccentric LVH demonstrated the most interstitial fibrosis and systolic strain impairment. LV remodelling had normal myocardial, but abnormal aortic, function. Greater understanding of the pathophysiology of HHD phenotypes may help tailor future treatments.

Age and hypertension strongly induce aortic stiffening in rats at basal and matched blood pressure levels.

Age and hypertension are major causes of large artery remodeling and stiffening, a cardiovascular risk factor for heart and kidney damage. The aged spontaneously hypertensive rat (SHR) model is recognized for human cardiovascular pathology, but discrepancies appeared in studies of arterial stiffness. We performed experiments using a robust analysis via echo tracking in 20‐week adult (n = 8) and 80‐week‐old SHR (n = 7), with age‐matched normotensive Wistar Kyoto rats (WKY, n = 6;6) at basal and matched levels of blood pressure (BP). After anesthesia with pentobarbital, abdominal aortic diameter and pressure were recorded and BP was decreased by clonidine i.v. At basal BP, aortic pulse distension, compliance, and distensibility (AD) were reduced and stiffness index increased with age and hypertension and further altered with age + hypertension. When BP was adjusted in SHR to that of normotensive rats (130 mmHg), there was no difference between 20‐week‐old SHR and WKY. Importantly, the age effect was maintained in both WKY and SHR and accentuated by hypertension in old rats. At 130 mmHg, with similar pulse pressure in the four groups, AD (kPa−3) = 24.2 ± 1 in 20 weeks WKY, 19.7 ± 1.4 in 20 weeks SHR, 12.4 ± 1.3 in 80 weeks WKY and 6.6 ± 0.6 in 80 weeks SHR; distension = 7.6 ± 0.4%, 6.7 ± 0.6%, 3.7 ± 0.3%, and 1.8 ± 0.2% in the same groups. In conclusion, reduced distensibility, that is, stiffening due to age is clearly shown here in both WKY and SHR as well as a synergistic effect of age and hypertension. This technique will allow new studies on the mechanisms responsible and drug intervention.

Abstract 102: Number of Reentry Tears Influences Flap Motion and Flow Reversal in an in vitro Model of Type B Aortic Dissection

Objectives: Aortic remodeling after dissection is poorly understood. Thus, optimal patient-specific recommendations for treatment are lacking. An in vitro aortic model of Type B dissection was used to interrogate local aortic hemodynamic parameters implicated in thrombosis and aneurysm formation. We hypothesize that dissections with multiple reentry tears will exhibit decreased flap motion, and, as a result, reduce flow reversal. Methods: Anatomic models of aortic dissection with fidelity to patient CT images were fabricated out of silicone. Models with primary entry and single fenestration (Figure 1A), two fenestrations (Figure 1B), and three fenestrations (Figure 1C) were installed in a flow loop. Physiologic flow was established at a cardiac index of 4 L/min. Flow velocities were acquired using phase contrast magnetic resonance (PCMR) imaging. Flow rates and flap motion were quantified using custom made software. Results: Relative true lumen area (RTLA) varied along the dissection (entry: 55% +/- 3, middle: 34% +/-7, exit: 91%+/-3, p&lt;0.00001 pair-wise for 2-tear model). At mid-dissection, RTLA was lower in dissections with fewer tears (p&lt;0.01). Total flow was nearly identical in all cases, while true and false lumen flow rates differed significantly across tear configurations and along the dissection (p&lt;0.01). Secondary tears allowed for flow communication within the dissected portion of the aortic model. Flow reversal was seen in the false lumen at the mid-dissection plane in the absence of secondary tears (Figure 1D). However, as secondary tears were added, the flow reversal in the false lumen decreased, with concomitant flow reversal in the true lumen (Figure 1E,F). Conclusions: Anatomic characteristics of dissection, such as number of tears, affect blood flow and motion of the dissection flap, as shown quantitatively. This compliant aorta model illustrates alterations in flow reversal in both true and false lumina that may lead to aneurysmal degeneration.

Hypertension and decreased aortic compliance due to reduced elastin amounts do not increase atherosclerotic plaque accumulation in Ldlr−/− mice

Background and aimsHigh blood pressure and reduced aortic compliance are associated with increased atherosclerotic plaque accumulation in humans. Animal studies support these associations, but additional factors, such as fragmented elastic fibers, are present in most previous animal studies. Elastin heterozygous (Eln+/−) mice have high blood pressure and reduced aortic compliance, with no evidence of elastic fiber fragmentation and represent an appropriate model to directly investigate the effects of these factors on atherosclerosis. Methods and resultsEln+/− and Eln+/+ mice were crossed with low density lipoprotein receptor knockout (Ldlr−/−) and wild-type (Ldlr+/+) mice and fed normal or Western diet (WD) for 16 weeks. We hypothesized that on WD, Eln+/−Ldlr−/− mice with high blood pressure and reduced aortic compliance would have increased atherosclerotic plaque accumulation compared to Eln+/+Ldlr−/− mice. We measured serum cholesterol and cytokine levels, blood pressure, aortic compliance, and plaque accumulation. Contrary to our hypothesis, we found that on WD, Eln+/−Ldlr−/− mice do not have increased plaque accumulation compared to Eln+/+Ldlr−/− mice. At the aortic root, there are no significant differences in plaque area between Eln+/−Ldlr−/− and Eln+/+Ldlr−/− mice on WD (p = 0.89), while in the ascending aorta, Eln+/−Ldlr−/− mice on WD have 29% less normalized plaque area than Eln+/+Ldlr−/− mice on WD (p = 0.009). ConclusionUsing an atherogenic mouse model, we conclude that increased blood pressure and reduced aortic compliance are not direct causes of increased aortic plaque accumulation. We propose that additional insults, such as fragmentation of elastic fibers, are necessary to alter plaque accumulation.

Elastic properties of ascending aorta in women with previous pregnancy complicated by early- or late-onset pre-eclampsia.

To evaluate the elastic properties of the ascending aorta in women with a previous pregnancy complicated by early-onset (EO) or late-onset (LO) pre-eclampsia (PE) and the correlation with gestational age (GA), systolic/diastolic blood pressure (SBP/DBP) and mean uterine artery pulsatility index (UtA-PI) at diagnosis of the disease as well as with birth weight of the neonate. Thirty women who had a previous pregnancy complicated by EO-PE, 30 with a previous pregnancy complicated by LO-PE and 30 normal controls were selected retrospectively from our electronic database and then recalled for assessment from 6 months to 4 years after delivery. Data regarding GA, SBP/DBP and mean UtA-PI at the diagnosis of PE were obtained from medical records. At our assessment, aortic M-mode and tissue Doppler imaging (TDI) parameters were measured. Aortic diameters were assessed at end-diastole at four levels: Valsalva sinuses, sinotubular junction, tubular tract and aortic arch. Aortic compliance, distensibility, stiffness index (SI), Peterson's elastic modulus (EM), pulse-wave velocity and M-mode strain were calculated using standard formulae. Aortic expansion velocity, early and late diastolic retraction velocities and peak systolic tissue strain (TDI-ϵ) were determined. Aortic diameters at the four levels were significantly greater in both EO-PE and LO-PE groups than in controls. Aortic compliance and distensibility and TDI-ϵ were lower in EO-PE than in LO-PE (P = 0.001, P = 0.002 and P = 0.011, respectively) and controls (P = 0.037, P = 0.044 and P = 0.013, respectively). SI and EM were higher in EO-PE than in LO-PE (P = 0.001 and P < 0.001, respectively) and than in controls (P = 0.035 and P = 0.036, respectively). Multivariate analysis showed GA, DBP and UtA-PI at diagnosis of PE to be independent predictors of aortic elastic properties. Elastic properties of the ascending aorta were altered in women with a previous pregnancy complicated by EO-PE, but not in those with LO-PE. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

MRI as a tool for non-invasive vascular profiling: a pilot study in patients with aortic coarctation

Aim: While the overall concept of aortic coarctation has changed from one of simple obstruction to one that includes significant vascular dysfunction, this has not yet been translated into the diagnostic and treatment process. To close this gap, we sought to demonstrate the usefulness of an additional non-invasive vascular profile. Method: During a pilot study in eight coarctation patients, aortic area compliance, aortic distensibility, time phase shift and blood flow (distribution) were calculated from cine-MRI and 2D-/4D-velocity-encoded MRI sequences. Results: Compared to healthy individuals, a significantly lower aortic compliance and reduced flow to the descending aorta were found in patients with coarctation. Discussion: These differences underline the potential usefulness of a combined vascular profile in coarctation patients. Conclusion: It was successfully shown that functional vascular profiling of the aorta is feasible to be acquired non-invasively in a clinical setting and can provide additional diagnostic information. These can be the key input parameters for computational fluid dynamics-modeling.