Validation and reproducibility of aortic pulse wave velocity as assessed with velocity-encoded MRI

Late effects of pediatric hematopoietic stem cell transplantation on left ventricular function, aortic stiffness and myocardial tissue characteristics

BACKGROUND

Pediatric hematopoietic stem cell transplantation (HSCT) recipients are at increased risk of cardiovascular disease later in life. As HSCT survival has significantly improved, with a growing number of HSCT indications, tailored screening strategies for HSCT-related late effects are warranted. Little is known regarding the value of cardiovascular magnetic resonance (CMR) for early identification of high-risk patients after HSCT, before symptomatic cardiovascular disease manifests. This study aimed to assess CMR-derived left ventricular (LV) systolic and diastolic function, aortic stiffness and myocardial tissue characteristics in young adults who received HSCT during childhood.

METHODS

Sixteen patients (22.1 ± 1.5 years) treated with HSCT during childhood and 16 healthy controls (22.1 ± 1.8 years) underwent 3 T CMR. LV systolic and diastolic function were measured as LV ejection fraction (LVEF), the ratio of transmitral early and late peak filling rate (E/A), the estimated LV filling pressure (E/Ea) and global longitudinal and circumferential systolic strain and diastolic strain rates, using balanced steady-state free precession cine CMR and 2D velocity-encoded CMR over the mitral valve. Aortic stiffness, myocardial fibrosis and steatosis were assessed with 2D velocity-encoded CMR, native T1 mapping and proton CMR spectroscopy (1H-CMRS), respectively.

RESULTS

In the patient compared to the control group, E/Ea (9.92 ± 3.42 vs. 7.24 ± 2.29, P = 0.004) was higher, LVEF (54 ± 6% vs. 58 ± 5%, P = 0.055) and global longitudinal strain (GLS) ( -20.7 ± 3.5% vs. -22.9 ± 3.0%, P = 0.063) tended to be lower, while aortic pulse wave velocity (4.40 ± 0.26 vs. 4.29 ± 0.29 m/s, P = 0.29), native T1 (1211 ± 36 vs. 1227 ± 28 ms, P = 0.16) and myocardial triglyceride content (0.47 ± 0.18 vs. 0.50 ± 0.13%, P = 0.202) were comparable. There were no differences between patients and controls in E/A (2.76 ± 0.92 vs. 2.97 ± 0.91, P = 0.60) and diastolic strain rates.

CONCLUSION

In young adults who received HSCT during childhood, LV diastolic function was decreased (higher estimated LV filling pressure) and LV systolic function (LVEF and GLS) tended to be reduced as compared to healthy controls, whereas no concomitant differences were found in aortic stiffness and myocardial tissue characteristics. When using CMR, assessment of LV diastolic function in particular is important for early detection of patients at risk of HSCT-related cardiovascular disease, which may warrant closer surveillance.

The reproducibility of cardiac magnetic resonance imaging measures of aortic stiffness and their relationship to cardiac structure in prevalent haemodialysis patients

BACKGROUND

Aortic stiffness is one of the earliest signs of cardiovascular disease (CVD) in patients with chronic kidney disease and an independent predictor of mortality. It is thought to drive left ventricular (LV) remodelling, an established biomarker for mortality. The relationship between direct and indirect measures of aortic stiffness and LV remodelling is not defined in dialysis patients, nor are the reproducibility of methods used to assess aortic stiffness using cardiac magnetic resonance (CMR) imaging.

METHODS

Using 3T CMR, we report the results of (i) the interstudy, interobserver and intra-observer reproducibility of ascending aortic distensibility (AAD), descending aortic distensibility (DAD) and aortic pulse wave velocity (aPWV) in 10 haemodialysis (HD) patients and (ii) the relationship between AAD, DAD and aPWV and LV mass index (LVMi) and LV remodelling in 70 HD patients.

RESULTS

Inter- and intra-observer variability of AAD, DAD and aPWV were excellent [intraclass correlation (ICC) > 0.9 for all]. Interstudy reproducibility of AAD was excellent {ICC 0.94 [95% confidence interval (CI) 0.78-0.99]}, but poor for DAD and aPWV [ICC 0.51 (-0.13-0.85) and 0.51 (-0.31-0.89)]. AAD, DAD and aPWV associated with LVMi on univariate analysis (β = -0.244, P = 0.04; β =-0.315, P < 0.001 and β = 0.242, P = 0.04, respectively). Only systolic blood pressure, serum phosphate and a history of CVD remained independent determinants of LVMi on multivariable linear regression.

CONCLUSIONS

AAD is the most reproducible CMR-derived measure of aortic stiffness in HD patients. CMR-derived measures of aortic stiffness were not independent determinants of LVMi in HD patients. Whether one should target blood pressure over aortic stiffness to mitigate cardiovascular risk still needs determination.

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.

MRI-derived aortic characteristics after pregnancy: The AMBITYON study

OBJECTIVES

Pregnancy and pregnancy complications have been associated with increased arterial stiffness even at young age. In this study we assessed the impact of parity on CMR-derived aortic characteristics as early markers of atherosclerosis and arterial stiffness in healthy women between 25 and 35 years.

STUDY DESIGN

We studied 68 women who participated in the AMBITYON study, a prospective population-based cohort study for assessment of atherosclerotic burden by MRI and traditional CVD risk factors in healthy, young adults. Of these women, 40 (58.8%) were nulliparous, 13 (19.1%) were primiparous and 15 (22.1%) were multiparous.

MAIN OUTCOME MEASURES

Descending thoracic aortic wall thickness (AWT) and pulse wave velocity (PWV) were measured using 3.0T CMR.

RESULTS

AWT measurements were similar between nulliparous women and primi- or multiparous women (1.6 mm ± 0.2 mm vs. 1.6 mm ± 0.2 mm; p = 0.79). Correction for age and systolic blood pressure did not change these results. Applying percentile based cut-off values showed a non-significant increase in AWT in parous women. PWV measurements did not differ between nulliparous women and parous women (4.5 m/s ± 0.7 m/s vs. 4.5 m/s ± 0.8 m/s; p = 0.78). Correction for age and systolic blood pressure did not influence these results. Using percentile based cut-off values, showed an increasing likelihood of higher PWV-values in parous women, although not statistically significant.

CONCLUSIONS

Direct measurement of aortic AWT and PWV by CMR showed no difference between nulliparous and parous women, probably indicating limited effect of pregnancy on arterial stiffness and early markers of atherosclerosis.

TRIAL REGISTRATION

Netherlands Trial Register (NTR) number: 4742.

Circulating levels of P-selectin and E-selectin relate to cardiovascular magnetic resonance-derived aortic characteristics in young adults from the general population, a cross-sectional study

BACKGROUND

Although endothelial cell adhesion molecules (CAMs) are postulated to play a key role in early atherosclerosis, studies on endothelial CAMs are mainly pertained to middle-aged populations and populations with an unfavourable cardiovascular risk burden. Therefore, this study evaluated whether circulating endothelial CAMs are related to cardiovascular magnetic resonance imaging (CMR) derived indicators of arterial wall alterations in a random sample of young adults from the general population.

METHODS

This cross-sectional study is part of the general-population-based Atherosclerosis-Monitoring-and-Biomarker-measurements-In-The-YOuNg (AMBITYON) cohort study. In 131 adults (age: 25-35 years), demography, anthropometry and a lipid spectrum was acquired. Thoracic aortic wall area, wall thickness and pulse wave velocity (PWV) were measured using a 3 T CMR-system. From stored blood samples, four CAMs (E-selectin, P-selectin, vascular CAM-1 and intercellular CAM-1) were measured using dedicated methods. Linear mixed-effects regression analysis was used to evaluate the relation of these CAMs with the selected aortic characteristics.

RESULTS

Of the studied endothelial CAMs, P-selectin related to natural logarithm transformed aortic wall thickness (β = 0.18 mm/(μg/ml), [95% confidence interval: 0.04, 0.31], p = 0.01) whereas E-selectin related to natural logarithm transformed aortic PWV (β = 3.01 (m/s)/(μg/ml), [95% confidence interval: 0.08, 5.95], p = 0.04). Of note, VCAM-1 and ICAM-1 did not relate to the selected aortic characteristics.

CONCLUSIONS

In young adults from the general population, circulating P-selectin and E-selectin levels appear positively related to CMR-derived aortic wall thickness and PWV, possibly pointing towards atherogenic inflammatory arterial wall alterations inflicted by these CAMs already in young adulthood.

TRIAL REGISTRATION

Netherlands National Trial Register (NTR): NTR4742 , Registered 18 August 2014, retrospectively registered.

Increased arterial stiffness in childhood onset diabetes: a cardiovascular magnetic resonance study

Aims

Arterial stiffness is a strong predictor of cardiovascular events. We aimed to assess the impact of type 1 diabetes (T1D) on arterial stiffness and cardiac function in young adults.

Methods and results

Aortic pulse wave velocity (PWV), distensibility, left ventricular (LV) function and LV mass were measured by cardiovascular magnetic resonance imaging (CMR) in 47 T1D patients and 33 healthy controls. All were participants in the Atherosclerosis and Childhood Diabetes study, with baseline values registered 5 years previously. The patients had a mean age of 20.8 years and a median duration of diabetes of 10.0 years. PWV was significantly higher in the diabetes group compared with controls, mean 4.10 (SD = 4.58) vs. 3.90 (SD = 4.04) m/s, P = 0.045. In the diabetes group, insulin pump users at baseline had lower PWV than multiple injection users, mean 3.94 (SD = 0.38) vs. 4.23 (SD = 0.48) m/s, P = 0.028. Also in the diabetes group, multiple regression analysis identified C-reactive protein (CRP), female gender and insulin pump use as independent baseline risk factors for PWV 5 years later. There was no difference in cardiac function or LV mass between the diabetes and control groups.

Conclusion

In this prospective study, we found increased PWV assessed by CMR in young adults with T1D compared with controls. Also, CRP, female gender and insulin pump use emerged as independent baseline risk factors for PWV 5 years later.

Imaging Insights on the Aorta in Aging

The aorta has 2 main functions, conduit and cushion, and is designed to transmit blood to the periphery and buffer pulsatile stress from ventricular contraction. In the interaction between the structural and functional changes of the aorta, aging and disease processes impact on aortic material properties and hemodynamics. For a comprehensive assessment of changes in aortic structure and function associated with aging and disease, noninvasive cardiovascular imaging techniques, especially magnetic resonance imaging, have recently been developed. Magnetic resonance imaging allows for direct and accurate measurement of different aortic characteristics including structural measures such as aortic area or volume, aortic length, curvature, and aortic wall thickness and functional measures such as aortic strain, distensibility, and pulse wave velocity. Excellent reproducibility of magnetic resonance imaging methods allows us to assess the response of the whole aorta to both pharmacological and nonpharmacological therapies. Aortic flow and functional assessment could be added to clinical routine cardiac magnetic resonance as a comprehensive imaging modality primarily performed for the noninvasive evaluation of left ventricular function, left ventricular load, and vascular/ventricular coupling. New techniques such as 4-dimensional flow could provide and further elucidate the combined age-related effects of altered aortic geometry and function. This following review will describe the pathophysiological aspects of the aorta and the ability, value, and prospects of cardiovascular imaging, especially magnetic resonance imaging, to study age-related changes in aortic structure and function and assess the relationship between these alterations and cardiovascular disease.

Determinants of impaired renal and vascular function are associated with elevated levels of procoagulant factors in the general population

Essentials Why venous thrombosis is more prevalent in chronic kidney disease is unclear. We investigated whether renal and vascular function are associated with hypercoagulability. Coagulation factors showed a procoagulant shift with impaired renal and vascular function. This suggests that renal and vascular function play a role in the etiology of thrombosis.

SUMMARY

Background Impaired renal and vascular function have been associated with venous thrombosis, but the mechanism is unclear. Objectives We investigated whether estimated glomerular filtration rate (eGFR), urinary albumin-creatinine ratio (UACR), and pulse wave velocity (PWV) are associated with a procoagulant state. Methods In this cross-sectional analysis of the NEO Study, eGFR, UACR, fibrinogen, and coagulation factors (F)VIII, FIX and FXI were determined in all participants (n = 6536), and PWV was assessed in a random subset (n = 2433). eGFR, UACR and PWV were analyzed continuously and per percentile: per six categories for eGFR (> 50th [reference] to < 1st) and UACR (< 50th [reference] to > 99th), and per four categories (< 50th [reference] to > 95th percentile) for PWV. Linear regression was used and adjusted for age, sex, total body fat, smoking, education, ethnicity, total cholesterol, C-reactive protein (CRP) and vitamin K antagonists use (FIX). Results Mean age was 55.6 years, mean eGFR 86.0 (12SD) mL 1.73 m- ² and median UACR 0.4 mg mmol-1 (25th, 75th percentile; 0.3, 0.7). All coagulation factors showed a procoagulant shift with lower renal function and albuminuria. For example, FVIII was 22 IU dL-1 (95% CI, 13-32) higher in the eGFR < 1st percentile compared with the > 50th percentile, and FVIII was 12 IU dL-1 (95% CI, 3-22) higher in the UACR > 99th percentile compared with the < 50th percentile. PWV was positively associated with coagulation factors FIX and FXI in continuous analysis; per m/s difference in PWV, FIX was 2.0 IU dL-1 (95% CI, 0.70-3.2) higher. Conclusions Impaired renal and vascular function was associated with higher levels of coagulation factors, underlining the role of renal function and vascular function in the development of venous thrombosis.

Utility of arterial stiffness assessment in children

Atherosclerotic cardiovascular disease is a leading cause of death and disability worldwide, and the atherosclerotic process begins in childhood. Prevention or containment of risk factors that accelerate atherosclerosis can delay the development of atherosclerotic cardiovascular disease. Although current recommendations are to periodically screen for commonly prevailing risk factors for atherosclerosis in children, a single test that could quantify the cumulative effect of all risk factors on the vasculature, thus assessing arterial health, would be helpful in further stratifying risk. Measurement of pulse wave velocity and assessment of augmentation index - measures of arterial stiffness - are easy-to-use, non-invasive methods of examining arterial health. Various studies have assessed pulse wave velocity and augmentation index in children with commonly occurring conditions including obesity, hypertension, insulin resistance, diabetes mellitus, dyslipidaemia, physical inactivity, chronic kidney disease, CHD and acquired heart diseases, and in children who were born premature or small for gestational age. This article summarises pulse wave velocity and augmentation index assessments and the effects of commonly prevailing chronic conditions on arterial health in children. In addition, currently available reference values for pulse wave velocity and augmentation index in healthy children are included. Further research to establish widely applicable normative values and the effect of lifestyle and pharmacological interventions on arterial health in children is needed.

Caloric restriction lowers endocannabinoid tonus and improves cardiac function in type 2 diabetes

BACKGROUND/OBJECTIVES

Endocannabinoids (ECs) are associated with obesity and ectopic fat accumulation, both of which play a role in the development of cardiovascular disease (CVD) in type 2 diabetes (T2D). The effect of prolonged caloric restriction on ECs in relation to fat distribution and cardiac function is still unknown. Therefore, our aim was to investigate this relationship in obese T2D patients with coronary artery disease (CAD).

SUBJECTS/METHODS

In a prospective intervention study, obese T2D patients with CAD (n = 27) followed a 16 week very low calorie diet (VLCD; 450-1000 kcal/day). Cardiac function and fat accumulation were assessed with MRI and spectroscopy. Plasma levels of lipid species, including ECs, were measured using liquid chromatography-mass spectrometry.

RESULTS

VLCD decreased plasma levels of virtually all measured lipid species of the class of N-acylethanolamines including the EC anandamide (AEA; -15%, p = 0.016), without decreasing monoacylglycerols including the EC 2-arachidonoylglycerol (2-AG). Baseline plasma AEA levels strongly correlated with the volume of subcutaneous white adipose tissue (SAT; R2 = 0.44, p < 0.001). VLCD decreased the volume of SAT (-53%, p < 0.001), visceral white adipose tissue (VAT) (-52%, p < 0.001), epicardial white adipose tissue (-15%, p < 0.001) and paracardial white adipose tissue (-28%, p < 0.001). VLCD also decreased hepatic (-86%, p < 0.001) and myocardial (-33%, p < 0.001) fat content. These effects were accompanied by an increased left ventricular ejection fraction (54.8 ± 8.7-56.2 ± 7.9%, p = 0.016).

CONCLUSIONS

Caloric restriction in T2D patients with CAD decreases AEA levels, but not 2-AG levels, which is paralleled by decreased lipid accumulation in adipose tissue, liver and heart, and improved cardiovascular function. Interestingly, baseline AEA levels strongly correlated with SAT volume. We anticipate that dietary interventions are worthwhile strategies in advanced T2D, and that reduction in AEA may contribute to the improved cardiometabolic phenotype induced by weight loss.

Rationale and design of Long-term Outcomes and Vascular Evaluation after Successful Coarctation of the Aorta Treatment study

Background:

Coarctation of the aorta (CoA) can be treated using surgery, balloon angioplasty, or stent implantation. Although short-term results are excellent with all three treatment modalities, long-term cardiovascular (CV) morbidity and mortality remain high, likely due to persistently abnormal vascular function. The effects of treatment modality on long-term vascular function remain uncharacterized. The goal of this study is to assess vascular function in this patient population for comparison among the treatment modalities.

Methods:

We will prospectively assess vascular Afunction in large and small arteries fusing multiple noninvasive modalities and compare the results among the three groups of CoA patients previously treated using surgery, balloon angioplasty, or stent implantation after frequency matching for confounding variables. A comprehensive vascular function assessment protocol has been created to be used in 7 centers. Our primary outcome is arterial stiffness measured by arterial tonometry. Inclusion and exclusion criteria have been carefully established after consideration of several potential confounders. Sample size has been calculated for the primary outcome variable.

Conclusion:

Treatment modalities for CoA may have distinct impact on large and small arterial vascular function. The results of this study will help identify the treatment modality that is associated with the most optimal level of vascular function, which, in the long term, may reduce CV risk.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

Prognostic Value of Aortic Stiffness in Patients After ST-Elevation Myocardial Infarction

BACKGROUND

High aortic stiffness has been shown to be a strong predictor of morbidity and mortality in the general population and several patient cohorts. However, in patients after ST-elevation myocardial infarction, the prognostic value of high aortic stiffness is unknown so far.

METHODS AND RESULTS

This prospective observational study included 160 consecutive patients with first acute ST-elevation myocardial infarction. Aortic pulse wave velocity (PWV) was measured 2 (interquartile range 2-4 days) days after infarction using cardiac magnetic resonance imaging. The primary end point was defined as a composite end point of major adverse cardiac and cerebrovascular events (MACCE) comprising death, nonfatal myocardial reinfarction, new congestive heart failure, and stroke. During a median follow-up of 1.2 years (interquartile range 1.0-3.1 years), 19 (12%) MACCE events occurred. Kaplan-Meier analysis showed a significantly lower MACCE-free survival in patients with high PWV (PWV >7.3 m/s, log-rank P=0.003). Multivariable Cox regression analysis revealed PWV >7.3 m/s to be an independent predictor of MACCE after adjustment for age, sex, mean blood pressure, N-terminal pro-brain natriuretic peptide levels, presence of multivessel disease, and left ventricular stroke volume (hazard ratios ≥3.5; 95% confidence interval 1.4-13.3; all P≤0.018). In reclassification analysis the addition of PWV to a risk model comprising major clinical prognostic parameters led to a net reclassification improvement of 0.11 (95% confidence interval 0.06-0.17; P<0.001).

CONCLUSIONS

Increased aortic stiffness is an independent predictor of MACCE after acute ST-elevation myocardial infarction. Moreover, the assessment of aortic stiffness in addition to classical risk factors significantly improved early risk stratification.

Magnetic Resonance Imaging of Cardiovascular Function and the Brain: Is Dementia a Cardiovascular-Driven Disease?

The proximal aorta acts as a coupling device between heart and brain perfusion, modulating the amount of pressure and flow pulsatility transmitted into the cerebral microcirculation. Stiffening of the proximal aorta is strongly associated with age and hypertension. The detrimental effects of aortic stiffening may result in brain damage as well as heart failure. The resulting cerebral small vessel disease and heart failure may contribute to early cognitive decline and (vascular) dementia. This pathophysiological sequence of events underscores the role of cardiovascular disease as a contributory mechanism in causing cognitive decline and dementia and potentially may provide a starting point for prevention and treatment. Magnetic resonance imaging is well suited to assess the function of the proximal aorta and the left ventricle (eg, aortic arch pulse wave velocity and distensibility) as well as the various early and late manifestations of cerebral small vessel disease (eg, microbleeds and white matter hyperintensities in strategically important regions of the brain). Specialized magnetic resonance imaging techniques are explored for diagnosing preclinical changes in white matter integrity or brain microvascular pulsatility.

Vessel wall characterization using quantitative MRI: what's in a number?

The past decade has witnessed the rapid development of new MRI technology for vessel wall imaging. Today, with advances in MRI hardware and pulse sequences, quantitative MRI of the vessel wall represents a real alternative to conventional qualitative imaging, which is hindered by significant intra- and inter-observer variability. Quantitative MRI can measure several important morphological and functional characteristics of the vessel wall. This review provides a detailed introduction to novel quantitative MRI methods for measuring vessel wall dimensions, plaque composition and permeability, endothelial shear stress and wall stiffness. Together, these methods show the versatility of non-invasive quantitative MRI for probing vascular disease at several stages. These quantitative MRI biomarkers can play an important role in the context of both treatment response monitoring and risk prediction. Given the rapid developments in scan acceleration techniques and novel image reconstruction, we foresee the possibility of integrating the acquisition of multiple quantitative vessel wall parameters within a single scan session.

Aortic Arch Pulse Wave Velocity Assessed by Magnetic Resonance Imaging as a Predictor of Incident Cardiovascular Events: The MESA (Multi-Ethnic Study of Atherosclerosis)

The predictive value of aortic arch pulse wave velocity (PWV) assessed by magnetic resonance imaging for cardiovascular disease (CVD) events has not been fully established. The aim of the present study was to evaluate the association of arch PWV with incident CVD events in MESA (Multi-Ethnic Study of Atherosclerosis). Aortic arch PWV was measured using magnetic resonance imaging at baseline in 3527 MESA participants (mean age, 62±10 years at baseline; 47% men) free of overt CVD. Cox regression was used to evaluate the risk of incident CVD (coronary heart disease, stroke, transient ischemic attack, or heart failure) in relation to arch PWV adjusted for age, sex, race, and CVD risk factors. The median value of arch PWV was 7.4 m/s (interquartile range, 5.6-10.2). There was significant interaction between arch PWV and age for outcomes, so analysis was stratified by age categories (45-54 and >54 years). There were 456 CVD events during the 10-year follow-up. Forty-five to 54-year-old participants had significant association of arch PWV with incident CVD independent of CVD risk factors (hazard ratio, 1.44; 95% confidence interval, 1.07-1.95; P=0.018; per 1-SD increase for logarithmically transformed PWV), whereas >54-year group did not (P=0.93). Aortic arch PWV assessed by magnetic resonance imaging is a significant predictor of CVD events among middle-aged (45-54 years old) individuals, whereas arch PWV is not associated with CVD among an elderly in a large multiethnic population.

Sex, body mass index, and blood pressure are related to aortic characteristics in healthy, young adults using magnetic resonance vessel wall imaging: the AMBITYON study

Objectives

More detailed evaluation of atherosclerosis and its key determinants in young individuals is warranted to improve knowledge on the pathophysiology of its development and progression. This study evaluated associations of magnetic resonance imaging (MRI)-derived aortic wall area, wall thickness, and pulse wave velocity (PWV) with cardiovascular risk factors in asymptomatic, young adults.

Materials and methods

In 124 adults (age: 25–35 years) from the general population-based Atherosclerosis Monitoring and Biomarker Measurements in the Young study, demography, anthropometry, and blood samples were collected. The studied MRI-parameters were measured using a 3.0T MRI system. Relations between cardiovascular risk factors and aortic characteristics were assessed using multivariable linear regression analyses.

Results

Mean age was 31.8 years, 47.6% was male. Aortic wall area was positively associated with age [β = 0.01, (95% confidence interval (CI) 2.00 × 10⁻³, 0.02), p = 0.01] and BMI [β = 0.01, (0.01, 0.02), p = 0.003] and negatively associated with sex (reference: men) [β = −0.06, (−0.11, −0.01), p = 0.02]. Natural logarithm transformed (ln) aortic wall thickness was positively associated with BMI [β = 0.01, (1.00 × 10⁻³, 0.02), p = 0.02]. Ln aortic PWV was positively associated with 10 mmHg increment of SBP [β = 0.06, (0.03, 0.09), p < 0.001] and DBP [β = 0.06, (0.02, 0.09), p = 0.006]. No relations were observed for smoking and lipids.

Conclusions

Already in early adulthood, aortic wall geometry and stiffness vary by age, sex, BMI, and blood pressure.

The importance of accurate measurement of aortic stiffness in patients with chronic kidney disease and end-stage renal disease

Cardiovascular (CV) disease is the leading cause of death in chronic kidney disease (CKD) and end-stage renal disease (ESRD). A key driver in this pathology is increased aortic stiffness, which is a strong, independent predictor of CV mortality in this population. Aortic stiffening is a potentially modifiable biomarker of CV dysfunction and in risk stratification for patients with CKD and ESRD. Previous work has suggested that therapeutic modification of aortic stiffness may ameliorate CV mortality. Nevertheless, future clinical implementation relies on the ability to accurately and reliably quantify stiffness in renal disease. Pulse wave velocity (PWV) is an indirect measure of stiffness and is the accepted standard for non-invasive assessment of aortic stiffness. It has typically been measured using techniques such as applanation tonometry, which is easy to use but hindered by issues such as the inability to visualize the aorta. Advances in cardiac magnetic resonance imaging now allow direct measurement of stiffness, using aortic distensibility, in addition to PWV. These techniques allow measurement of aortic stiffness locally and are obtainable as part of a comprehensive, multiparametric CV assessment. The evidence cannot yet provide a definitive answer regarding which technique or parameter can be considered superior. This review discusses the advantages and limitations of non-invasive methods that have been used to assess aortic stiffness, the key studies that have assessed aortic stiffness in patients with renal disease and why these tools should be standardized for use in clinical trial work.

Association of Aortic Stiffness With Left Ventricular Remodeling and Reduced Left Ventricular Function Measured by Magnetic Resonance Imaging: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

This study sought to assess cross-sectional associations of aortic stiffness assessed by magnetic resonance imaging with left ventricular (LV) remodeling and myocardial deformation in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS AND RESULTS

Aortic arch pulse wave velocity (PWV) was measured with phase contrast cine magnetic resonance imaging. LV circumferential strain (Ecc), torsion, and early diastolic strain rate were determined by tagged magnetic resonance imaging. Multivariable linear regression models were used to adjust for demographics and cardiovascular risk factors. Of 2093 participants, multivariable linear regression models demonstrated that higher arch PWV was associated with higher LV mass index (B=0.53 per 1 SD increase for log-transformed PWV, P<0.05) and LV mass to volume ratio (B=0.015, P<0.01), impaired LV ejection fraction (LVEF; B=-0.84; P<0.001), Ecc (B=0.55; P<0.001), torsion (B=-0.11; P<0.001), and early diastolic strain rate (B=-0.003; P<0.05). In sex stratified analysis, higher arch PWV was associated with higher MVR (B=0.02; P<0.05), impaired Ecc (B=0.60; P<0.001), and LVEF (B=-0.45; P<0.05), but with maintained torsion in women. Higher PWV was associated with impaired Ecc (B=0.49; P<0.001) and LVEF (B=-1.21; P<0.001), with lower torsion (B=-0.17; P<0.001) in men.

CONCLUSIONS

Higher arch PWV is associated with LV remodeling, and reduced LV systolic and diastolic function in a large multiethnic population. Greater aortic arch stiffness is associated with concentric LV remodeling and relatively preserved LVEF with maintained torsion in women, whereas greater aortic arch stiffness is associated with greater LV dysfunction demonstrated as impaired Ecc, torsion, and LVEF, with less concentric LV remodeling in men.

Proximal aortic stiffening in Turner patients may be present before dilation can be detected: a segmental functional MRI study

BACKGROUND

To study segmental structural and functional aortic properties in Turner syndrome (TS) patients. Aortic abnormalities contribute to increased morbidity and mortality of women with Turner syndrome. Cardiovascular magnetic resonance (CMR) allows segmental study of aortic elastic properties.

METHOD

We performed Pulse Wave Velocity (PWV) and distensibility measurements using CMR of the thoracic and abdominal aorta in 55 TS-patients, aged 13-59y, and in a control population (n = 38;12-58y). We investigated the contribution of TS on aortic stiffness in our entire cohort, in bicuspid (BAV) versus tricuspid (TAV) aortic valve-morphology subgroups, and in the younger and older subgroups.

RESULTS

Differences in aortic properties were only seen at the most proximal aortic level. BAV Turner patients had significantly higher PWV, compared to TAV Turner (p = 0.014), who in turn had significantly higher PWV compared to controls (p = 0.010). BAV Turner patients had significantly larger ascending aortic (AA) luminal area and lower AA distensibility compared to both controls (all p < 0.01) and TAV Turner patients. TAV Turner had similar AA luminal areas and AA distensibility compared to Controls. Functional changes are present in younger and older Turner subjects, whereas ascending aortic dilation is prominent in older Turner patients. Clinically relevant dilatation (TAV and BAV) was associated with reduced distensibility.

CONCLUSION

Aortic stiffening and dilation in TS affects the proximal aorta, and is more pronounced, although not exclusively, in BAV TS patients. Functional abnormalities are present at an early age, suggesting an aortic wall disease inherent to the TS. Whether this increased stiffness at young age can predict later dilatation needs to be studied longitudinally.

Unravelling cardiovascular disease using four dimensional flow cardiovascular magnetic resonance

Knowledge of normal and abnormal flow patterns in the human cardiovascular system increases our understanding of normal physiology and may help unravel the complex pathophysiological mechanisms leading to cardiovascular disease. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has emerged as a suitable technique that enables visualization of in vivo blood flow patterns and quantification of parameters that could potentially be of prognostic value in the disease process. In this review, current image processing tools that are used for comprehensive visualization and quantification of blood flow and energy distribution in the heart and great vessels will be discussed. Also, imaging biomarkers extracted from 4D flow CMR will be reviewed that have been shown to distinguish between normal and abnormal flow patterns. Furthermore, current applications of 4D flow CMR in the heart and great vessels will be discussed, showing its potential as an additional diagnostic modality which could aid in disease management and timing of surgical intervention.

Reference Values for Cardiac and Aortic Magnetic Resonance Imaging in Healthy, Young Caucasian Adults

Background

Reference values for morphological and functional parameters of the cardiovascular system in early life are relevant since they may help to identify young adults who fall outside the physiological range of arterial and cardiac ageing. This study provides age and sex specific reference values for aortic wall characteristics, cardiac function parameters and aortic pulse wave velocity (PWV) in a population-based sample of healthy, young adults using magnetic resonance (MR) imaging.

Materials and Methods

In 131 randomly selected healthy, young adults aged between 25 and 35 years (mean age 31.8 years, 63 men) of the general-population based Atherosclerosis-Monitoring-and-Biomarker-measurements-In-The-YOuNg (AMBITYON) study, descending thoracic aortic dimensions and wall thickness, thoracic aortic PWV and cardiac function parameters were measured using a 3.0T MR-system. Age and sex specific reference values were generated using dedicated software. Differences in reference values between two age groups (25–30 and 30–35 years) and both sexes were tested.

Results

Aortic diameters and areas were higher in the older age group (all p<0.007). Moreover, aortic dimensions, left ventricular mass, left and right ventricular volumes and cardiac output were lower in women than in men (all p<0.001). For mean and maximum aortic wall thickness, left and right ejection fraction and aortic PWV we did not observe a significant age or sex effect.

Conclusion

This study provides age and sex specific reference values for cardiovascular MR parameters in healthy, young Caucasian adults. These may aid in MR guided pre-clinical identification of young adults who fall outside the physiological range of arterial and cardiac ageing.

Aortic stiffening and its impact on left atrial volumes and function in patients after successful coarctation repair: a multiparametric cardiovascular magnetic resonance study

BACKGROUND

The increased cardiovascular morbidity of adults with late repair of aortic coarctation (CoA) has been well documented. In contrast, successful CoA repair in early childhood has a generally good prognosis, though adverse vascular and ventricular characteristics may be abnormal, which could increase long-term risk. This study sought to perform a comprehensive analysis of aortic elasticity and left ventricular (LV) function in patients with aortic coarctation (CoA) using cardiovascular magnetic resonance (CMR). In a subgroup of patients, we assessed structure and function of the common carotid arteries to probe for signs of systemic vascular remodeling.

METHODS

Fifty-one patients (median age 17.3 years), 13.9 ± 7.5 years after CoA repair, and 54 controls (median age 19.8 years) underwent CMR. We determined distensibility and pulse wave velocity (PWV) at different aortic locations. In a subgroup, common carotid artery distensibility, PWV, wall thickness and wall area were measured. LV ejection fraction (EF), volumes, and mass were measured from short axis views. Left atrial (LA) volumes and functional parameters (LAEFPassive, LAEFContractile, LAEFReservoir) were assessed from axial cine images.

RESULTS

In patients distensibility of the whole thoracic aorta was reduced (p < 0.05) while PWV was only significantly higher in the aortic arch (p < 0.01). Distensibility of the descending aorta at the level of the pulmonary arteries and PWV in the descending aorta, both correlated negatively with age at CoA repair. LA volume before atrial contraction and minimal LA volume were higher in patients (p < 0.05). LAEFPassive and LAEFReservoir were reduced (p < 0.05), and LAEFReservoir correlated negatively with aortic arch PWV (p < 0.05). LVEF, volumes and mass were not different from controls. Carotid wall thickness and PWV were higher in patients compared to controls (p < 0.05).

CONCLUSIONS

Patients after CoA repair have impaired bioelastic properties of the thoracic aorta with impact on LV diastolic function. Reduced descending aortic elasticity is associated with older age at time of CoA repair. The remodeling of the common carotid artery in our sub-study suggests systemic vessel wall changes.

Ballistocardiogram: Mechanism and Potential for Unobtrusive Cardiovascular Health Monitoring

For more than a century, it has been known that the body recoils each time the heart ejects blood into the arteries. These subtle cardiogenic body movements have been measured with increasingly convenient ballistocardiography (BCG) instruments over the years. A typical BCG measurement shows several waves, most notably the “I”, “J”, and “K” waves. However, the mechanism for the genesis of these waves has remained elusive. We formulated a simple mathematical model of the BCG waveform. We showed that the model could predict the BCG waves as well as physiologic timings and amplitudes of the major waves. The validated model reveals that the principal mechanism for the genesis of the BCG waves is blood pressure gradients in the ascending and descending aorta. This new mechanistic insight may be exploited to allow BCG to realize its potential for unobtrusive monitoring and diagnosis of cardiovascular health and disease.

Invasive aortic pulse wave velocity as a marker for arterial stiffness predicts outcome of renal sympathetic denervation

AIMS

A recurrent finding of trials on renal sympathetic denervation is a certain percentage of non-responders. The aim of this study was to examine the influence of arterial stiffness to predict response.

METHODS AND RESULTS

Eighty-eight patients were included in the study. Arterial stiffness was measured by invasive pulse wave velocity. Antihypertensive medication had to be unchanged during follow-up. Ambulatory blood pressure measurement (ABPM) was used to record blood pressure before and six months after denervation. Fifty-eight patients without changes in medication were included in the final analysis. Responders (n=37; blood pressure reduction -12.8±6.4 mmHg) had a significantly lower pulse wave velocity (14.4±4.4 m/s versus 17.7±4.5 m/s; p=0.009) compared to non-responders (n=21; blood pressure reduction +3.0±4.5 mmHg; p<0.001 for comparison with responders). In multivariate analysis, invasive pulse wave velocity was the only significant predictor of blood pressure reduction after denervation (odds ratio 1.15, 95% confidence interval [CI] 1.014-1.327; p=0.03). Patients with increased stiffness were older (p=0.001), had a higher prevalence of diabetes (p=0.008), more often had isolated systolic hypertension (p=0.007), and had a higher invasive pulse pressure (p<0.001).

CONCLUSIONS

Patients with lower pulse wave velocity showed a significantly better response to denervation. These findings emphasise that pulse wave velocity might be used as a selection criterion for renal denervation.

Association of Aortic Compliance and Brachial Endothelial Function with Cerebral Small Vessel Disease in Type 2 Diabetes Mellitus Patients: Assessment with High-Resolution MRI

Objective. To assess the possible association of aortic compliance and brachial endothelial function with cerebral small vessel disease in type 2 diabetes mellitus (DM2) patients by using 3.0 T high-resolution magnetic resonance imaging. Methods. Sixty-two clinically confirmed DM2 patients (25 women and 37 men; mean age: 56.8 ± 7.5 years) were prospectively enrolled for noninvasive MR examinations of the aorta, brachial artery, and brain. Aortic arch pulse wave velocity (PWV), flow-mediated dilation (FMD) of brachial artery, lacunar brain infarcts, and periventricular and deep white matter hyperintensities (WMHs) were assessed. Pearson and Spearman correlation analysis were performed to analyze the association between PWV and FMD with clinical data and biochemical test results. Univariable logistic regression analyses were used to analyze the association between PWV and FMD with cerebral small vessel disease. Multiple logistic regression analyses were used to find out the independent predictive factors of cerebral small vessel disease. Results. Mean PWV was 6.73 ± 2.00 m/s and FMD was 16.67 ± 9.11%. After adjustment for compounding factors, PWV was found significantly associated with lacunar brain infarcts (OR = 2.00; 95% CI: 1.14–3.2; P < 0.05) and FMD was significantly associated with periventricular WMHs (OR = 0.82; 95% CI: 0.71–0.95; P < 0.05). Conclusions. Quantitative evaluation of aortic compliance and endothelial function by using high-resolution MRI may be potentially useful to stratify DM2 patients with risk of cerebral small vessel disease.

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.

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.

Required temporal resolution for accurate thoracic aortic pulse wave velocity measurements by phase-contrast magnetic resonance imaging and comparison with clinical standard applanation tonometry

Background

Pulse wave velocity (PWV) is a biomarker for arterial stiffness, clinically assessed by applanation tonometry (AT). Increased use of phase-contrast cardiac magnetic resonance (CMR) imaging allows for PWV assessment with minor routine protocol additions. The aims were to investigate the acquired temporal resolution needed for accurate and precise measurements of CMR-PWV, and develop a tool for CMR-PWV measurements.

Methods

Computer phantoms were generated for PWV = 2–20 m/s based on human CMR-PWV data. The PWV measurements were performed in 13 healthy young subjects and 13 patients at risk for cardiovascular disease. The CMR-PWV was measured by through-plane phase-contrast CMR in the ascending aorta and at the diaphragm level. Centre-line aortic distance was determined between flow planes. The AT-PWV was assessed within 2 h after CMR. Three observers (CMR experience: 15, 4, and <1 year) determined CMR-PWV. The developed tool was based on the flow-curve foot transit time for PWV quantification.

Results

Computer phantoms showed bias 0.27 ± 0.32 m/s for a temporal resolution of at least 30 ms. Intraobserver variability for CMR-PWV were: 0 ± 0.03 m/s (15 years), -0.04 ± 0.33 m/s (4 years), and -0.02 ± 0.30 m/s (<1 year). Interobserver variability for CMR-PWV was below 0.02 ± 0.38 m/s. The AT-PWV overestimated CMR-PWV by 1.1 ± 0.7 m/s in healthy young subjects and 1.6 ± 2.7 m/s in patients.

Conclusions

An acquired temporal resolution of at least 30 ms should be used to obtain accurate and precise thoracic aortic phase-contrast CMR-PWV. A new freely available research tool was used to measure PWV in healthy young subjects and in patients, showing low intra- and interobserver variability also for less experienced CMR observers.

Prognostic value of cardiovascular MR imaging biomarkers on outcome in peripheral arterial disease: a 6-year follow-up pilot study

The objective of this pilot study was to explore the prognostic value of outcome of cardiovascular magnetic resonance (MR) imaging biomarkers in patients with symptomatic peripheral arterial disease (PAD) in comparison with traditional risk factors. Forty-two consecutive patients (mean age 64 ± 11 years, 22 men) referred for contrast-enhanced MR angiography (CE-MRA) were included. At baseline a comprehensive cardiovascular MRI examination was performed: CE-MRA of the infra-renal aorta and run-off vessels, carotid vessel wall imaging, cardiac cine imaging and aortic pulse wave velocity (PWV) assessment. Patients were categorized for outcome at 72 ± 5 months follow-up. One patient was lost to follow-up. Over 6 years, six patients had died (mortality rate 14.6 %), six patients (14.6 %) had experienced a cardiac event and three patients (7.3 %) a cerebral event. The mean MRA stenosis class (i.e., average stenosis severity visually scored over 27 standardized segments) was a significant independent predictor for all-cause mortality (beta 3.0 ± standard error 1.3, p = 0.02). Descending aorta PWV, age and diabetes mellitus were interrelated with stenosis severity but none of these were significant independent predictors. For cardiac morbidity, left ventricular ejection fraction (LVEF) and mean MRA stenosis class were associated, but only LVEF was a significant independent predictor (beta -0.14 ± 0.05, p = 0.005). Diabetes mellitus was a significant independent predictor for cerebral morbidity (beta 2.8 ± 1.3, p = 0.03). Significant independent predictors for outcome in PAD are mean MRA stenosis class for all-cause mortality, LVEF for cardiac morbidity and diabetes mellitus for cerebral morbidity.

Ten-year longitudinal change in aortic stiffness assessed by cardiac MRI in the second half of the human lifespan: the multi-ethnic study of atherosclerosis

AIMS

Longitudinal determinants of aortic stiffness (AS) measured by magnetic resonance imaging (MRI) have not been assessed in a large community-based population. Our aim was to examine the determinants of change in thoracic AS over 10 years of follow-up in a multi-ethnic population of individuals 45 years of age and older measured by MRI.

METHODS AND RESULTS

We studied 1160 participants (mean age = 60 ± 9 years at baseline, 45% male) with aortic MRI at both the MESA Year 0 and Year 10 examinations. Ascending and descending aorta distensibility (AAD/DAD) and aortic arch pulse-wave velocity (PWV) were measured using MRI. Determinants of the change in AS parameters over 10 years were assessed using linear regression adjusted for baseline values, demographic variables, baseline risk factors and change in risk factors, and chronic risk exposure. AAD and DAD decreased slightly (5% decrease in median for AAD: 1.33-1.26 mmHg(-1) · 10(-3), P = 0.008; 5% decrease in median for DAD: 1.73-1.64 mmHg(-1) · 10(-3), P < 0.001), and PWV increased over 10 years (18% increase in median: 6.8-8.0 m/s P < 0.001). Baseline age was related to a reduction in AAD and DAD and an increase in PWV throughout the follow-up period. Baseline and change in mean blood pressure and continued smoking were associated with a reduction in AAD and an increase in PWV. Furthermore, baseline heart rate was also related to a reduction in AAD and DAD. Blood pressure normalization was related to less aortic stiffening throughout the follow-up period.

CONCLUSIONS

In our longitudinal, community-based cohort study of adult individuals aged 45 years or greater, greater mean blood pressure and a history of smoking history were associated with increased aortic stiffening over 10 years as assessed by MRI.

Clinical effects of phosphodiesterase 3A mutations in inherited hypertension with brachydactyly

Autosomal-dominant hypertension with brachydactyly is a salt-independent Mendelian syndrome caused by activating mutations in the gene encoding phosphodiesterase 3A. These mutations increase the protein kinase A-mediated phosphorylation of phosphodiesterase 3A resulting in enhanced cAMP-hydrolytic affinity and accelerated cell proliferation. The phosphorylated vasodilator-stimulated phosphoprotein is diminished, and parathyroid hormone-related peptide is dysregulated, potentially accounting for all phenotypic features. Untreated patients die prematurely of stroke; however, hypertension-induced target-organ damage is otherwise hardly apparent. We conducted clinical studies of vascular function, cardiac functional imaging, platelet function in affected and nonaffected persons, and cell-based assays. Large-vessel and cardiac functions indeed seem to be preserved. The platelet studies showed normal platelet function. Cell-based studies demonstrated that available phosphodiesterase 3A inhibitors suppress the mutant isoforms. However, increasing cGMP to indirectly inhibit the enzyme seemed to have particular use. Our results shed more light on phosphodiesterase 3A activation and could be relevant to the treatment of severe hypertension in the general population.

Estimation of aortic pulse wave transit time in cardiovascular magnetic resonance using complex wavelet cross-spectrum analysis

BACKGROUND

Aortic pulse wave velocity (PWV), which substantially increases with arterial stiffness and aging, is a major predictor of cardiovascular mortality. It is commonly estimated using applanation tonometry at carotid and femoral arterial sites (cfPWV). More recently, several cardiovascular magnetic resonance (CMR) studies have focused on the measurement of aortic arch PWV (archPWV). Although the excellent anatomical coverage of CMR offers reliable segmental measurement of arterial length, accurate transit time (TT) determination remains a challenge. Recently, it has been demonstrated that Fourier-based methods were more robust to low temporal resolution than time-based approaches.

METHODS

We developed a wavelet-based method, which enables temporal localization of signal frequencies, to estimate TT from ascending and descending aortic CMR flow curves. This method (archPWVWU) combines the robustness of Fourier-based methods to low temporal resolution with the possibility to restrict the analysis to the reflectionless systolic upslope. We compared this method with Fourier-based (archPWVF) and time domain upslope (archPWVTU) methods in relation to linear correlations with age, cfPWV and effects of decreasing temporal resolution by factors of 2, 3 and 4. We studied 71 healthy subjects (45 ± 15 years, 29 females) who underwent CMR velocity acquisitions and cfPWV measurements.

RESULTS

Comparison with age resulted in the highest correlation for the wavelet-based method (archPWVWU:r = 0.84,p < 0.001; archPWVTU:r = 0.74,p < 0.001; archPWVF:r = 0.63,p < 0.001). Associations with cfPWV resulted in the highest correlations for upslope techniques whether based on wavelet (archPWVWU:r = 0.58,p < 0.001) or time (archPWVTU:r = 0.58,p < 0.001) approach. Furthermore, while decreasing temporal resolution by 4-fold induced only a minor decrease in correlation of both archPWVWU (r decreased from 0.84 to 0.80) and archPWVF (r decreased from 0.63 to 0.51) with age, it induced a major decrease for the archPWVTU age relationship (r decreased from 0.74 to 0.38).

CONCLUSIONS

By CMR, measurement of aortic arch flow TT using systolic upslopes resulted in a better correlation with age and cfPWV, as compared to the Fourier-based approach applied on the entire cardiac cycle. Furthermore, methods based on harmonic decomposition were less affected by low temporal resolution. Since the proposed wavelet approach combines these two advantages, it might help to overcome current technical limitations related to CMR temporal resolution and evaluation of patients with highly stiff arteries.

Coupling between MRI-assessed regional aortic pulse wave velocity and diameters in patients with thoracic aortic aneurysm: a feasibility study

AIMS

Thoracic aortic aneurysm (TAA) is potentially life-threatening and requires close follow-up to prevent aortic dissection. Aortic stiffness and size are considered to be coupled. Regional aortic stiffness in patients with TAA is unknown. We aimed to evaluate coupling between regional pulse wave velocity (PWV), a marker of vascular stiffness, and aortic diameter in TAA patients.

METHODS

In 40 TAA patients (59 ± 13 years, 28 male), regional aortic diameters and regional PWV were assessed by 1.5 T MRI. The incidence of increased diameter and PWV were determined for five aortic segments (S1, ascending aorta; S2, aortic arch; S3, thoracic descending aorta; S4, suprarenal and S5, infrarenal abdominal aorta). In addition, coupling between regional PWV testing and aortic dilatation was evaluated and specificity and sensitivity were assessed.

RESULTS

Aortic diameter was 44 ± 5 mm for the aortic root and 39 ± 5 mm for the ascending aorta. PWV was increased in 36 (19 %) aortic segments. Aortic diameter was increased in 28 (14 %) segments. Specificity of regional PWV testing for the prediction of increased regional diameter was ≥ 84 % in the descending thoracic to abdominal aorta and ≥ 68 % in the ascending aorta and aortic arch.

CONCLUSION

Normal regional PWV is related to absence of increased diameter, with high specificity in the descending thoracic to abdominal aorta and moderate results in the ascending aorta and aortic arch.

Biomarkers of hemodynamic stress and aortic stiffness after STEMI: a cross-sectional analysis

Aim. Increased aortic stiffness might adversely affect cardiac structure, function, and perfusion. Release of biomarkers of hemodynamic stress is thought to be enhanced by these alterations. We aimed to evaluate the association between biomarkers of hemodynamic stress and aortic stiffness assessed at a chronic stage after ST-segment elevation myocardial infarction (STEMI). Methods. Fifty-four patients four months after STEMI were enrolled in this cross-sectional, single-center study. N-terminal pro–B-type natriuretic peptide (NT-proBNP), mid-regional pro–A-type natriuretic peptide (MR-proANP), and mid-regional proadrenomedullin (MR-proADM) levels were measured by established assays. Aortic stiffness was assessed by the measurement of pulse wave velocity using phase-contrast cardiovascular magnetic resonance. Results. NT-proBNP, MR-proANP, and MR-proADM concentrations were all correlated with aortic stiffness in univariate analysis (r = 0.378, r = 0.425, and r = 0.532; all P < 0.005, resp.). In multiple linear regression analysis, NT-proBNP (β = 0.316, P = 0.005) and MR-proADM (β = 0.284, P < 0.020) levels were associated with increased aortic stiffness independently of age, blood pressure, and renal function. NT-proBNP was the strongest predictor for high aortic stiffness (area under the curve: 0.82, 95% CI 0.67–0.96). Conclusion. At a chronic stage after STEMI, concentrations of biomarkers for hemodynamic stress, especially NT-proBNP, are positively correlated with aortic stiffness. These biomarkers might also be useful as predictors of high aortic stiffness after STEMI.

High-temporal velocity-encoded MRI for the assessment of left ventricular inflow propagation velocity: Comparison with color M-mode echocardiography

PURPOSE

To develop an alternative method for Vp-assessment using high-temporal velocity-encoded magnetic resonance imaging (VE-MRI). Left ventricular (LV) inflow propagation velocity (Vp) is considered a useful parameter in the complex assessment of LV diastolic function and is measured by Color M-mode echocardiography.

MATERIALS AND METHODS

A total of 43 patients diagnosed with ischemic heart failure (61 ± 11 years) and 22 healthy volunteers (29 ± 13 years) underwent Color M-mode echocardiography and VE-MRI to assess the inflow velocity through the mitral valve (mean interexamination time 14 days). Temporal resolution of VE-MRI was 10.8-11.8 msec. Local LV inflow velocity was sampled along a 4-cm line starting from the tip of the mitral leaflets and for consecutive sample points the point-in-time was assessed when local velocity exceeded 30 cm/s. From the position-time relation, Vp was calculated by both the difference quotient (Vp-MRI-DQ) as well as from linear regression (Vp-MRI-LR).

RESULTS

Good correlation was found between Vp-echo and both Vp-MRI-DQ (r = 0.83, P < 0.001) and Vp-MRI-LR (r = 0.84, P < 0.001). Vp-MRI showed a significant but small underestimation as compared to Vp measured by echocardiography (Vp-MRI-DQ: 5.5 ± 16.2 cm/s, P = 0.008; Vp-MRI-LR: 9.9 ± 15.2 cm/s, P < 0.001). Applying age-related cutoff values for Vp to identify LV impaired relaxation, kappa-agreement with echocardiography was 0.72 (P < 0.001) for Vp-MRI-DQ and 0.69 (P < 0.001) for Vp-MRI-LR.

CONCLUSION

High temporal VE-MRI represents a novel approach to assess Vp, showing good correlation with Color M-mode echocardiography. In healthy subjects and patients with ischemic heart failure, this new method demonstrated good agreement with echocardiography to identify LV impaired relaxation.

Cardiovascular flexibility in middle-aged overweight South Asians vs. white Caucasians: response to short-term caloric restriction

BACKGROUND AND AIMS

South Asians have a higher risk of developing cardiovascular disease than white Caucasians. The underlying cause is unknown, but might be related to higher cardiac susceptibility to metabolic disorders. Short-term caloric restriction (CR) can be used as a metabolic stress test to study cardiac flexibility. We assessed whether metabolic and functional cardiovascular flexibility to CR differs between South Asians and white Caucasians.

METHODS AND RESULTS

Cardiovascular function and myocardial triglycerides were assessed using a 1.5T-MRI/S-scanner in 12 middle-aged overweight male South Asians and 12 matched white Caucasians before and after an 8-day very low calorie diet (VLCD). At baseline South Asians were more insulin resistant than Caucasians. Cardiac dimensions were smaller, despite correction for body surface area, and pulse wave velocity (PWV) in the distal aorta was higher in South Asians. Systolic and diastolic function, myocardial triglycerides and pericardial fat did not differ significantly between groups. After the VLCD body weight reduced on average by 4.0 ± 0.2 kg. Myocardial triglycerides increased in both ethnicities by 69 ± 18%, and diastolic function decreased although this was not significant in South Asians. However, pericardial fat and PWV in the proximal and total aorta were reduced in Caucasians only.

CONCLUSION

Myocardial triglyceride stores in middle-aged overweight and insulin resistant South Asians are as flexible and amenable to therapeutic intervention by CR as age-, sex- and BMI-matched but less insulin resistant white Caucasians. However, paracardial fat volume and PWV showed a differential effect in response to an 8-day VLCD in favor of Caucasians.

CLINICAL TRIAL REGISTRATION

NTR 2473 (URL: http://www.trialregister.nl/trialreg/admin/rctsearch.asp?Term=2473).

Higher oily fish consumption in late pregnancy is associated with reduced aortic stiffness in the child at age 9 years

RATIONALE

Higher pulse wave velocity (PWV) reflects increased arterial stiffness and is an established cardiovascular risk marker associated with lower long-chain n-3 polyunsaturated fatty acid intake in adults. Experimentally, maternal fatty acid intake in pregnancy has lasting effects on offspring arterial stiffness.

OBJECTIVE

To examine the association between maternal consumption of oily fish, a source of long-chain n-3 polyunsaturated fatty acids, in pregnancy and child's aortic stiffness age 9 years.

METHODS AND RESULTS

In a mother-offspring study (Southampton Women's Survey), the child's descending aorta PWV was measured at the age of 9 years using velocity-encoded phase-contrast MRI and related to maternal oily fish consumption assessed prospectively during pregnancy. Higher oily fish consumption in late pregnancy was associated with lower childhood aortic PWV (sex-adjusted β=-0.084 m/s per portion per week; 95% confidence interval, -0.137 to -0.031; P=0.002; n=226). Mother's educational attainment was independently associated with child's PWV. PWV was not associated with the child's current oily fish consumption.

CONCLUSIONS

Level of maternal oily fish consumption in pregnancy may influence child's large artery development, with potential long-term consequences for later cardiovascular risk.

Comparison of an oscillometric method with cardiac magnetic resonance for the analysis of aortic pulse wave velocity

Objectives

Pulse wave velocity (PWV) is the proposed gold-standard for the assessment of aortic elastic properties. The aim of this study was to compare aortic PWV determined by a recently developed oscillometric device with cardiac magnetic resonance imaging (CMR).

Methods

PWV was assessed in 40 volunteers with two different methods. The oscillometric method (PWV_OSC) is based on a transfer function from the brachial pressure waves determined by oscillometric blood pressure measurements with a common cuff (Mobil-O-Graph, I.E.M. Stolberg, Germany). CMR was used to determine aortic PWV_CMR with the use of the transit time method based on phase-contrast imaging at the level of the ascending and abdominal aorta on a clinical 1.5 Tesla scanner (Siemens, Erlangen, Germany).

Results

The median age of the study population was 34 years (IQR: 24–55 years, 11 females). A very strong correlation was found between PWVOSC and PWVCMR (r = 0.859, p < 0.001). Mean PWV_OSC was 6.7 ± 1.8 m/s and mean PWVCMR was 6.1 ± 1.8 m/s (p < 0.001). Analysis of agreement between the two measurements using Bland-Altman method showed a bias of 0.57 m/s (upper and lower limit of agreement: 2.49 m/s and -1.34 m/s). The corresponding coefficient of variation between both measurements was 15%.

Conclusion

Aortic pulse wave velocity assessed by transformation of the brachial pressure waveform showed an acceptable agreement with the CMR-derived transit time method.