Elevated Aortic Augmentation Index in Children Following Fontan Palliation: Evidence of Stiffer Arteries?

Arterial Stiffness in Congenital Heart Disease

Transposition of the great arteries (TGA), coarctation of the aorta (CoA), single ventricle (SV) and tetralogy of Fallot (ToF) are forms of congenital heart disease (CHD). Despite advances in treatment, cardiovascular and cerebrovascular complications in patients with repaired CHD occur earlier in life compared to healthy subjects. A factor that may contribute to this increased risk is elevated arterial stiffness. This systematic review provides a critical assessment of current evidence on central arterial stiffness in patients with CHD compared to healthy controls. In July 2020, Medline OVID, EMBASE and Scopus were searched using keywords and MeSH terms. Articles were included if they reported indices of aortic or carotid artery stiffness in patients with TGA, CoA, SV or ToF, and compared these to controls. Additional studies were screened from the reference lists of included articles. Of 1,033 studies identified, 43 were included in the final review. Most studies identified at least one index of central arterial stiffness, commonly in the aortic root or ascending aorta, that was higher in patients with CHD compared to controls. The commonly reported surrogate markers of stiffness were pulse wave velocity, aortic distensibility and the β stiffness index. There was a relatively small number of original studies, and synthesis of data was limited by methodological heterogeneity, highlighting the need for further studies with standardised methods. However, there was consistent evidence of early and/or accelerated arterial stiffening in CHD patients, which may contribute to the increased risk of adverse cardiovascular and cerebrovascular events in this population.

Aortic pressure and forward and backward wave components in children, adolescents and young-adults: Agreement between brachial oscillometry, radial and carotid tonometry data and analysis of factors associated with their differences

Non-invasive devices used to estimate central (aortic) systolic pressure (cSBP), pulse pressure (cPP) and forward (Pf) and backward (Pb) wave components from blood pressure (BP) or surrogate signals differ in arteries studied, techniques, data-analysis algorithms and/or calibration schemes (e.g. calibrating to calculated [MBPc] or measured [MBPosc] mean pressure). The aims were to analyze, in children, adolescents and young-adults (1) the agreement between cSBP, cPP, Pf and Pb obtained using carotid (CT) and radial tonometry (RT) and brachial-oscillometry (BOSC); and (2) explanatory factors for the differences between approaches-data and between MBPosc and MBPc.1685 subjects (mean/range age: 14/3-35 y.o.) assigned to three age-related groups (3-12; 12-18; 18-35 y.o.) were included. cSBP, cPP, Pf and Pb were assessed with BOSC (Mobil-O-Graph), CT and RT (SphygmoCor) records. Two calibration schemes were considered: MBPc and MBPosc for calibrations to similar BP levels. Correlation, Bland-Altman tests and multiple regression models were applied. Systematic and proportional errors were observed; errors´ statistical significance and values varied depending on the parameter analyzed, methods compared and group considered. The explanatory factors for the differences between data obtained from the different approaches varied depending on the methods compared. The highest cSBP and cPP were obtained from CT; the lowest from RT. Independently of the technique, parameter or age-group, higher values were obtained calibrating to MBPosc. Age, sex, heart rate, diastolic BP, body weight or height were explanatory factors for the differences in cSBP, cPP, Pf or Pb. Brachial BP levels were explanatory factors for the differences between MBPosc and MBPc.

Arterial Stiffness and Its Relationship to Cardiorespiratory Fitness in Children and Young Adults with a Fontan Circulation

There are no previous studies on arterial stiffness and its associations with cardiorespiratory fitness in young Fontan patients. Therefore, we examined the arterial stiffness and its relationship to cardiorespiratory fitness in children and young adults with a Fontan circulation. Altogether, 17 Fontan patients and 26 healthy controls (16 females and 27 males aged 8-40 years) participated in this cross-sectional study. The cardiorespiratory fitness was assessed by cardiopulmonary exercise testing on a cycle ergometer and was defined as the standard deviation scores (SDS) of peak oxygen uptake per body mass (VO_2peak/kg) based on the national reference values and assessed with cardiopulmonary exercise testing on a cycle ergometer. Aortic pulse wave velocity (PWV_ao) as a measure of arterial stiffness and aortic Augmentation Index (AIX) as a measure of peripheral arterial tone, were assessed by non-invasive oscillometric device from upper arm. Body adiposity was determined by body mass index SDS and the sport participation by interview. Data were analyzed using linear regression analyses and Pearson's correlations, adjusted for age and sex. Fontan patients had a lower VO_2peak/kg-SDS (- 2.69 vs 0.078), higher PWV_ao-SDS (1.13 vs - 0.24) and higher AIX (19.26% vs 8.49%) in comparison with healthy controls. PWV_ao and AIX were negatively associated with VO_2peak/kg (standard regression coefficient (β) - 0.525, 95% confidence interval (CI) - 0.722 to - 0.227, p < 0.01 and β - 0.371, 95% CI - 0.672 to - 0.080, p = 0.014). Young Fontan patients have the arterial stiffness of healthy people who are twice as old. Thereby, children and young adults with a Fontan circulation have a lower cardiorespiratory fitness and less sport participation. Arterial stiffness is inversely associated with cardiorespiratory fitness and exercise training might be an intervention to improve vascular health in this population.

Aortic dilatation in complex congenital heart disease

A bicuspid aortic valve and/or coarctation of the aorta (COA) are often associated with dilatation of the ascending aorta and para-coarctation. Congenital heart diseases (CHD), such as truncus arteriosus, transposition of the great arteries (TGA), tetralogy of Fallot (TOF), hypoplastic left heart syndrome (HLHS), single ventricle with pulmonary stenosis/atresia and the Fontan procedure, are also associated with aortic root dilatation, aneurysm and rarely, dissection, which can be fatal and require aortic valve and root surgery. A significant subset of adults with complex CHD exhibit progressive dilatation of the aortic root even after repair due to aortic medial degeneration. Medial degeneration in the ascending aorta is prevalent among the above CHD. In Marfan syndrome, bicuspid aortic valve and COA, medial degeneration is more extensive and severe than in another complex CHD. Accordingly, the incidence of ascending aortic dilatation, dissection and rupture is higher in the former. This aortic medial degeneration in CHD may either be intrinsic or secondary to the increased volume overload of the aortic root due to right-to-left shunting, or a combination of both. The association of aortic pathophysiological abnormalities, aortic dilatation and aorto-ventricular interaction is clinically referred to as "aortopathy". The major purpose of medical treatment for aortopathy is to reduce the structural changes within the aortic wall and slow down the progression of aortic dilatation to reduce the risk of cardiovascular events. Several medications have been studied, including β-blockers, angiotensin II type I (AT1) receptor blockers (ARBs) and Ca-antagonists. However, the results, except for Marfan syndrome, are limited. In aortopathy, concomitant aortic valve and aortic root repair/replacement is required. The Bentall operation comprises root replacement with an aortic tube graft and mechanical valve, and has been widely applied. On the other hand, valve-sparing operations have been developed in order to preserve the aortic valve.

Increased arterial stiffness in children with congenital heart disease

Objective Central systolic blood pressure (SBP) is a measure of arterial stiffness and strongly associated with atherosclerosis and end-organ damage. It is a stronger predictor of cardiovascular events and all-cause mortality than peripheral SBP. In particular, for children with congenital heart disease, a higher central SBP might impose a greater threat of cardiac damage. The aim of the study was to analyse and compare central SBP in children with congenital heart disease and in healthy counterparts. Patients and methods Central SBP was measured using an oscillometric method in 417 children (38.9% girls, 13.0 ± 3.2 years) with various congenital heart diseases between July 2014 and February 2017. The test results were compared with a recent healthy reference cohort of 1466 children (49.5% girls, 12.9 ± 2.5 years). Results After correction for several covariates in a general linear model, central SBP of children with congenital heart disease was significantly increased (congenital heart disease: 102.1 ± 10.2 vs. healthy reference cohort: 100.4 ± 8.6, p < .001). The analysis of congenital heart disease subgroups revealed higher central SBP in children with left heart obstructions (mean difference: 3.6 mmHg, p < .001), transpositions of the great arteries after arterial switch (mean difference: 2.2 mmHg, p = .017) and univentricular hearts after total cavopulmonary connection (mean difference: 2.1 mmHg, p = .015) compared with the reference. Conclusion Children with congenital heart disease have significantly higher central SBP compared with healthy peers, predisposing them to premature heart failure. Screening and long-term observations of central SBP in children with congenital heart disease seems warranted in order to evaluate the need for treatment.

Histopathological abnormalities in the central arteries and veins of Fontan subjects

OBJECTIVE

Fontan circulations have obligatory venous hypertension, depressed cardiac output and abnormal arterial elastance. Ventriculovascular coupling is known to be abnormal, but the underlying mechanisms are poorly defined. We aim to describe the histopathological features of vascular remodelling encountered in the central arteries and veins in the Fontan circulation as a possible underlying pathological representation of abnormal ventriculovascular coupling.

METHODS

Postmortemvasculature (inferior vena cava (IVC), superior vena cava (SVC), pulmonary artery (PA), pulmonary vein (PV) and aorta) of 13 patients with a Fontan circulation (mean age 29.9 years, range 9.0-59.8 years) and 2 biventricular controls (ages 17.9 and 30.2 years) was examined.

RESULTS

IVC and SVC: Eccentric and variable intimal fibromuscular proliferation occurred in 11 Fontan subjects. There was variable loss of medial smooth muscle bundles with reciprocal replacement with dense collagenous tissue.PA: Similar intimal fibromuscular proliferation was seen; however, these intimal changes were accompanied by medial thinning rather than expansion, medial myxoid degeneration and elastic alteration.PV: The PVs demonstrated intimal fibroproliferation and disorganisation of the muscular media.Aorta: The aortic lamina intima was thickened, with associated fibromuscular proliferation and elasticisation. There was also moderate lymphocytic inflammation in the aortic wall.

CONCLUSIONS

Vascular architectural remodelling is common in Fontan patients. The central veins demonstrate profound changes of eccentric intimal expansion and smooth muscle replacement with collagen. The pulmonary demonstrated abnormal intimal proliferation, and aortic remodelling was characterised by intima lamina thickening and a moderate degree of aortic wall inflammation.

Association between human immunodeficiency virus infection and arterial stiffness in children

Background Human immunodeficiency virus infection (HIV) is associated with increased cardiovascular risk and adverse cardiovascular outcome in adults. Early recognition of changes in vascular properties might prove essential in cardiovascular prevention in HIV-infected patients. We investigated the relations between HIV infection and arterial stiffness in children. Methods This cross-sectional study included 51 HIV-infected and 52 healthy children (age 3.2-14.5 years, 49 males). All infected children had acquired HIV by vertical transmission and were receiving antiretroviral therapy at time of assessment. Arterial stiffness was measured by pulse wave velocity and aortic augmentation index, using the Arteriograph system (Tensiomed Kft, Budapest, Hungary). We applied multivariable general linear modeling to evaluate the relationship between HIV infection and arterial stiffness with further adjustment for confounders and possible intermediary variables. Findings represent mean group differences with 95% confidence intervals and p values. Results Aortic augmentation index was higher by 9.0% (5.6-12.5, p < 0.001) in HIV-infected than in healthy children. Adjustment for blood pressure, protease inhibitor use, biomarkers for level of inflammation, lipid- and glucose-metabolism, as possible intermediary variables, did not appreciably alter the results. There were no significant differences in pulse wave velocity between HIV-infected and healthy children (mean difference 0.28 m/s, -0.14-0.69, p = 0.19). Conclusion HIV-infected children have an increased aortic augmentation index, compared to healthy children. Early cardiovascular assessment may be important in targeted prevention for HIV-infected children.

Arterial stiffness and arterial function in adult cyanotic patients with congenital heart disease

BACKGROUND

Mortality in cyanotic patients with congenital heart diseases (CHD) is high, mainly due to cardiovascular complications. It is known that endothelial dysfunction, increased arterial stiffness, and impaired vascular function have negative influence on cardiovascular prognosis. The aim of the study was to assess parameters of arterial stiffness and vascular dysfunction in cyanotic patients with CHD as well as their potential relation to impaired blood oxygen saturation and polycythemia parameters typical for cyanosis.

METHODS

A total of 36 CHD cyanotic patients (17 males) (42.3±16.3 years) and 35 healthy individuals (16 males) (39.6±10.4 years) were enrolled. Assessed parameters were intima media thickness and flow-mediated dilatation (FMD). Assessed parameters using applanation tonometry methods were aortic systolic pressure, aortic pulse pressure (AoPP), augmentation pressure (AP), augmentation index (AI), pulse pressure amplification (PPampl), and pulse wave velocity (PWV).

RESULTS

AoPP (37.3±11.1mmHg vs. 29±6.5mmHg; p=0.002), AP (10.1±7.3mmHg vs. 1.1±3.9mmHg; p=0.00001), AI (24.7±13.5% vs. 3.0±13.6%; p=0.00001), and PWV (7.4±2.1m/s vs. 6.3±0.7m/s; p=0.003) were higher, and PPampl was lower (135.3±16.1% vs. 160.4±12.8%; p=0.00001) in the studied group compared to controls and proved the presence of the increased stiffness of arteries. Impairment of FMD was observed (9.0±5.6 vs. 10.9±4.7; p=0.04). No significant correlations were found between analyzed arterial parameters and biochemical ones characterizing cyanotic patients depicting rheological properties of blood.

CONCLUSIONS

Cyanotic patients with CHD are characterized by increased arterial stiffness estimated with pulse wave analysis parameters and by deteriorated arterial function expressed with worse vasodilatative response in comparison with healthy population. It may confirm relevance of those mechanisms in development of increased rate of cardiovascular events in this population. Association between oxygen saturation or polycythemia and arterial stiffening or vascular dysfunction was not found in these patients.

Changes in Central Aortic Pressure Levels, Wave Components and Determinants Associated with High Peripheral Blood Pressure States in Childhood: Analysis of Hypertensive Phenotype

The aims were to determine whether children's high peripheral blood pressure states (HBP) are associated with increased central aortic blood pressure (BP) and to characterize hemodynamic and vascular changes associated with HBP in terms of changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR) and net and relative contributions of reflected waves to the aortic pulse amplitude. We included 154 subjects (mean age 11; range 4-16 years) assigned to one of two groups: normal peripheral BP (NBP, n = 101), defined as systolic and diastolic BP < 90th percentile, or high BP (HBP, n = 53), defined as average systolic and/or diastolic BP levels ≥90th percentile (curves for sex, age and body height). The HBP group included children with hypertensive and pre-hypertensive BP levels. After a first analysis, groups were compared excluding obese and dyslipidemic children. Peripheral and central aortic BP, PWV and pulse wave-derived parameters (augmentation index, forward and backward wave components' amplitude) were measured using gold-standard techniques, applanation tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). Independent of the presence of dyslipidemia and/or obesity, aortic systolic and pulse BP were higher in HBP than in NBP children. The increase in central BP could not be explained by an increase in the relative contribution of reflections to the aortic pressure wave, higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP would be explained by an increase in the amplitude of both incident and reflected wave components.