Towards improving the lived experience of adult congenital heart patients: suggestions for health care practitioners.

What steps may clinicians looking after adult congenital heart patients take to improve the care they provide? An adult with complex congenital heart disease (CHD) who required a Fontan circulation has developed a discussion paper with the help of his attending clinicians. Drawing on his personal experience and that of others that he has represented, the paper highlights the problems in communication between such patients and their physician, followed by suggestions as to how to improve patient engagement, empowerment, and enablement. Attention to those suggestions may well benefit all in the care provided for this growing population.

Influence of accelerated arterial aging in growth-restricted cohorts on adult-onset cardiovascular diseases.

Epidemiologists have long documented a higher risk of adult-onset cardiovascular diseases (CVDs) such as stroke, hypertension, and coronary artery disease, as well as mortality from circulatory causes in low birth-weight cohorts (poor in utero substrate supply). Utero-placental insufficiency and in utero hypoxemic state-induced alterations in arterial structure and compliance are important initiating factors for adult-onset hypertension. The mechanistic links between fetal growth restriction and CVD include decreased arterial wall elastin-to-collagen ratio, endothelial dysfunction, and heightened renin-angiotensin-aldosterone system (RAAS). Systemic arterial thickness on fetal ultrasound and vascular changes in placental histopathology in growth restricted cohorts indicate fetal/developmental origins of adult-onset circulatory diseases. Similar findings of impaired arterial compliance have been noticed across age groups (neonates through to adults). Such changes augment what occurs as "normal arterial aging," resulting in accelerated arterial aging. Data from animal models suggest that hypoxemia-associated vascular adaptations enacted in utero are region specific, reflecting long-term vascular pathology. In this review, we explore the influence of birthweight and prematurity on blood pressure and arterial stiffness, demonstrating impaired arterial dynamics in growth-restricted cohorts across age groups, explain how early arterial aging influences adult-onset CVDs, describe pathophysiology data from experimental models and finally, discuss interventions which may influence aging by way of altering various cellular and molecular mechanisms of arterial aging. Age-appropriate interventions which have noted efficacy include prolonged breastfeeding and high polyunsaturated fatty acids dietary intake. Targeting the RAAS seems a promising approach. New data indicate activation of sirtuin 1 and maternal resveratrol may have beneficial effects.

Fifteen-minute consultation: Pathophysiology of postural orthostatic tachycardia syndrome in children and adolescents: diagnosis and management strategies.

Postural orthostatic tachycardia syndrome (POTS) affects children and adolescents-normally fit and well and yet troubled by a myriad of everyday symptoms. Understanding the pathophysiology of this not uncommon disorder together with a review of the clinical features may well assist the attending clinicians to arrive at a clear diagnosis without the need for extensive testing and multiple investigations. Simple lifestyle measures such as increasing fluid intake, electrolyte and/or salt supplements, adequate sleep, not missing out on meals and instituting an exercise programme to improve muscle tone and strength may avoid the need of pharmacological management. These simple measures may benefit symptoms which generally improve as adulthood approaches. In addition, it is important to recognise the comorbidities that may be associated with POTS, each of which may require specific management strategies. This paper reviews the pathophysiology, clinical features and recommended treatment in the management of POTS.

Cardiorespiratory adaptation to low-dose dexamethasone for lung disease in extremely preterm infants: A prospective echocardiographic study.

The cardiovascular impact of dexamethasone (Dex) is not well understood. Most data are obtained from a 6 week, high-dose regimen, and are limited to findings of hypertension and cardiac hypertrophy. The present study ascertained the impact of low-dose Dex on cardiac indices when administered to extremely preterm infants for lung disease. A pre-post intervention prospective echocardiographic (Echo) study was undertaken, with cardiac assessments performed before and within 24 h after completion of first course of therapy (10 day regimen, cumulative 0.89 mg kg-1 ). Thirty infants with a gestational age of 24.6 ± 1.1 weeks and birthweight of 612 ± 125 g, respectively, were studied. The age at Dex administration was 20 ± 9 days. Fractional inspired oxygen decreased from 0.7 ± 0.23 to 0.35 ± 0.14 (P < 0.001). Patent ductus arteriosus was noted in 20 infants at Echo1. At Echo2, the ductal diameter decreased from 2.16 ± 0.8 to 1.1 ± 0.8 mm (P = 0.0003), with complete closure in 7/20 (35%). A reduction in left pulmonary artery end-diastolic velocity was noted (17 ± 12 to 9 ± 10 cm s-1 , P < 0.001). Pulmonary vascular resistance decreased (increased time to peak velocity/right ventricular ejection time, 0.2 ± 0.03 to 0.23  ± 0.03, P = 0.0001) and right ventricular systolic performance improved (tricuspid annular plane systolic excursion, 4.9 ± 0.8 to 5.5 ± 0.9 mm, P = 0.02). No significant changes in fractional shortening and left ventricular mass were noted. A significant increase in blood pressure was noted. As a percentage of pre-treatment baseline, the mean increase for systolic blood pressure was 20.3% (95% confidence interval = 14-26) on day 2 (P = 0.008). Low-dose Dex influenced cardiovascular parameters related to pulmonary circulation. KEY POINTS: Corticosteroid therapy is frequently used in preterm infants who are dependent on ventilator support. Echocardiographic studies in infants administered a 6 week course of steroids have noted left ventricular hypertrophy, outlet obstruction and hypertension, but no information is available on right heart indices. The cardiopulmonary effects of the current, significantly lesser cumulative dose (10 day regimen, commonly described as 'DART') have not been evaluated. The present study noted a significant influence on ductal and pulmonary circulation indices. Left heart architecture and function was maintained, whereas a significant but transient increase in blood pressure was noted.

Mitral valve Doppler for cardiac output assessment in preterm neonates.

INTRODUCTION: Cardiac output (CO) assessment in neonates is commonly done by echocardiography. It is unclear which is the best site to measure the left ventricular (LV) outflow tract for CO assessment (the aortic valve [AV] aortic sinus [AS] or the sinotubular junction [STJ]). In the normal heart, the blood flow entering the LV equals the blood ejected from it. Therefore, measuring the blood flow into the LV through the mitral valve (MV) is an alternative way to measure CO. METHODS: In stable preterm infants the MV CO was compared with the right ventricular (RV) CO and the three ways to measure LV CO, in 30 stable preterm neonates. Interobserver variability for MV CO was established. RESULTS: In the 30 neonates studied, MV CO was best correlated and had a minimal bias to the RV CO and LV CO measured at the STJ. Left ventricular CO measured at the AV and AS had significant bias relative to RV CO and MV CO. MV CO inter-observer variability was similar to other echocardiographic CO assessment methods. CONCLUSION: MV CO may be used as an alternative way to assess CO. The STJ may be the optimal site to measure LV outflow tract.

Melody valve insertion for relief of "Tricuspid" stenosis in an unbalanced atrioventricular septal defect.

A Melody valve was successfully placed across a very stenotic right-sided component of a common atrioventricular valve because of ongoing troublesome arrhythmias in a young woman with an unbalanced atrioventricular septal defect, a very dilated right atrium and a hypoplastic right ventricle. Four years later, she remains well.

Fifteen-minute consultation: How to spot serious heart disease in the newborn.

Congenital heart disease (CHD) is common and important as it remains a leading cause of neonatal morbidity and appreciable mortality. Prenatal diagnosis, the presence of a murmur, cyanosis, tachypnoea and/or poor or differential peripheral pulses raise the suspicion of CHD aided by differential pre/postductal saturations. Yet even serious CHD may not be considered when such clues are absent. Nevertheless, there are clinical cues which may alert the clinician to the possibility of a significant CHD which may lead to an early and accurate diagnosis and appropriate intervention to achieve best results. This paper addresses these issues which become especially difficult if caring for infants away from facilities provided by tertiary centres. Tachypnoea on the first postnatal day is generally non-cardiac in origin. Exceptions include large arteriovenous fistulae and/or 'pump' (ventricular) failure. In addition, attention is drawn to two important confounding factors in the newborn, namely the patency of the ductus arteriosus and the initially high pulmonary vascular resistance, both of which alter and may mask the clinical findings of a serious cardiac abnormality. An appreciation of the physiological changes that occur in early infancy will aid the clinician's understanding of CHD as it affects the newborn.

Phenotypes of adults with congenital heart disease around the globe: a cluster analysis.

OBJECTIVE: To derive cluster analysis-based groupings for adults with congenital heart disease (ACHD) when it comes to perceived health, psychological functioning, health behaviours and quality of life (QoL). METHODS: This study was part of a larger worldwide multicentre study called APPROACH-IS; a cross sectional study which recruited 4028 patients (2013-2015) from 15 participating countries. A hierarchical cluster analysis was performed using Ward's method in order to group patients with similar psychological characteristics, which were defined by taking into consideration the scores of the following tests: Sense Of Coherence, Health Behavior Scale (physical exercise score), Hospital Anxiety Depression Scale, Illness Perception Questionnaire, Satisfaction with Life Scale and the Visual Analogue Scale scores of the EQ-5D perceived health scale and a linear analogue scale (0-100) measuring QoL. RESULTS: 3768 patients with complete data were divided into 3 clusters. The first and second clusters represented 89.6% of patients in the analysis who reported a good health perception, QoL, psychological functioning and the greatest amount of exercise. Patients in the third cluster reported substantially lower scores in all PROs. This cluster was characterised by a significantly higher proportion of females, a higher average age the lowest education level, more complex forms of congenital heart disease and more medical comorbidities. CONCLUSIONS: This study suggests that certain demographic and clinical characteristics may be linked to less favourable health perception, quality of life, psychological functioning, and health behaviours in ACHD. This information may be used to improve psychosocial screening and the timely provision of psychosocial care.

Early detection of significant congenital heart disease: The contribution of fetal cardiac ultrasound and newborn pulse oximetry screening.

Fetal cardiac and newborn pulse oximetry screening has greatly facilitated the detection of cardiac abnormalities, which may be serious with potentially dire neonatal consequences. The prenatal diagnosis of a serious cardiac abnormality allows the attending obstetrician to organise the much safer in-utero transfer of the fetus for delivery at a tertiary centre, particularly if there is evidence of a duct-dependent lesion that may require the infusion of Prostaglandin E1 to maintain duct patency pending surgical intervention. Newborn pulse oximetry alerts the paediatrician that the baby may have a significant cardiac abnormality, which warrants further elucidation prior to discharge, rather than for the baby to represent unwell a few days later. Despite these advances, serious cardiac abnormalities may be missed on screening. Their detection then falls back onto the clinical acumen of the attending paediatrician/family physician to review the history, carefully elicit and evaluate the clinical signs further aided by whatever investigations that may be available at the birthing hospital, frequently less resourced than the tertiary centres. At the outset, a brief synopsis is provided of the clinical findings that may point to a cardiac abnormality. That is followed by a critical review of the accuracy of prenatal and newborn pulse oximetry screening with emphasis on the lesions that may be missed. Suggestions are made as to how to improve the diagnostic accuracy.

Impact of Skin-to-Skin Parent-Infant Care on Preterm Circulatory Physiology.

OBJECTIVES: To ascertain the impact of skin-to-skin care between parents and infants on cardiac function and cerebral blood flow in preterm infants. STUDY DESIGN: We undertook a prospective study of 40 self-ventilating preterm infants at a quaternary center and assessed cardiac performance and cerebral blood flow. Assessments were carried out two hours before skin-to-skin care and then 60 minutes after skin-to-skin care (with the infant still on parent and turned supine). RESULTS: Infants were 30.5 ± 0.6 weeks' gestational age and 1378 ± 133 g birthweight. Axillary temperature noted a nonsignificant increase during skin-to-skin care from 36.7 ± 0.07°C to 36.9 ± 0.07°C (P = .07). Cardiac contractility (right ventricular fractional area change [26.5% ± 0.3% vs 27.8% ± 0.4; P < .001] and tricuspid annular plane systolic excursion [0.73 ± 0.03 cm vs 0.77 ± 0.03 cm; P = .02]) increased significantly, coincident with decreased measures of pulmonary vascular resistance. An increase in systemic cardiac output was associated with increased cerebral blood flow and reduced middle cerebral artery resistive index (0.81 ± 0.02 vs 0.74 ± 0.02; P = .0001). CONCLUSIONS: We documented a significant circulatory beneficial adaptation to a common neonatal practice. These findings align with previously documented physiologic benefits in cardiorespiratory stability and cardiac rhythm in preterm infants, and may be mediated through modulation of the autonomic nervous system.

Impact of echocardiography on parental anxiety in children with innocent murmurs.

AIM: Heart murmurs are not uncommon in childhood. Once noted, they may induce appreciable parental anxiety even if the likely diagnosis is that of an innocent murmur. This study aimed to clarify if a confirmatory echocardiogram may increase parental understanding and reduce their anxiety even though the murmur had been diagnosed as being innocent by an experienced paediatric cardiologist. METHODS: Parents of children referred to a paediatric cardiologist for evaluation of a murmur were asked to complete a State Trait Anxiety Inventory after the cardiologist's clinical diagnosis of an innocent murmur. The questionnaire was repeated after cross-sectional echocardiography to assess if there was a change in the parental understanding regarding their child's murmur and to review their level of anxiety. RESULTS: Over the time available for the study, 62 parents were recruited consecutively wherever possible. Forty-eight (77%) completed both questionnaires. There was a reduction in the state anxiety level following the echocardiogram in parents who exhibited a high (n = 23) or even a low-level trait anxiety (n = 25) (P < 0.05). Enhanced parental understanding of the diagnosis was also demonstrated. CONCLUSIONS: Reduced parental anxiety and an increase in their understanding after echocardiography suggested that the procedure may have an important role in the management of innocent murmurs even after the initial reassurance by a paediatric cardiologist.

Healthcare system inputs and patient-reported outcomes: a study in adults with congenital heart defect from 15 countries.

BACKGROUND: The relationship between healthcare system inputs (e.g., human resources and infrastructure) and mortality has been extensively studied. However, the association between healthcare system inputs and patient-reported outcomes remains unclear. Hence, we explored the predictive value of human resources and infrastructures of the countries' healthcare system on patient-reported outcomes in adults with congenital heart disease. METHODS: This cross-sectional study included 3588 patients with congenital heart disease (median age = 31y; IQR = 16.0; 52% women; 26% simple, 49% moderate, and 25% complex defects) from 15 countries. The following patient-reported outcomes were measured: perceived physical and mental health, psychological distress, health behaviors, and quality of life. The assessed inputs of the healthcare system were: (i) human resources (i.e., density of physicians and nurses, both per 1000 people) and (ii) infrastructure (i.e., density of hospital beds per 10,000 people). Univariable, multivariable, and sensitivity analyses using general linear mixed models were conducted, adjusting for patient-specific variables and unmeasured country differences. RESULTS: Sensitivity analyses showed that higher density of physicians was significantly associated with better self-reported physical and mental health, less psychological distress, and better quality of life. A greater number of nurses was significantly associated with better self-reported physical health, less psychological distress, and less risky health behavior. No associations between a higher density of hospital beds and patient-reported outcomes were observed. CONCLUSIONS: This explorative study suggests that density of human resources for health, measured on country level, are associated with patient-reported outcomes in adults with congenital heart disease. More research needs to be conducted before firm conclusions about the relationships observed can be drawn. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02150603. Registered 30 May 2014.

Does Echocardiography Have a Role in the Cardiologist's Diagnosis of Innocent Murmurs in Childhood?

BACKGROUND: Innocent murmurs are common in childhood. Echocardiography may diagnose almost all congenital cardiac abnormalities. Earlier studies have suggested that it may be unnecessary when a clinical diagnosis of an innocent murmur is made by an experienced cardiologist. Yet, echocardiography is commonly performed despite such a diagnosis. Is that justifiable? METHODS: Patients referred to a paediatric cardiologist for evaluation of a murmur were assessed. If an innocent murmur was clinically diagnosed, an echocardiogram and an electrocardiogram were ordered when requested. The cardiologist completed a questionnaire documenting the reasons for the investigations and his degree of confidence in the clinical diagnosis. The parents and patients were informed of the diagnosis and the results of the investigations. RESULTS: In almost all 62 cases whose murmurs were clinically considered to be innocent, the referring doctor expected an echocardiogram to be performed. Following echocardiography, one patient was found to have a small muscular ventricular septal defect. On review, the murmur was consistent with that diagnosis. Three (3) others had abnormal echocardiograms namely congenitally corrected transposition of great arteries, partial anomalous right upper lobe pulmonary vein, and left ventricular non-compaction. All on review were still considered clinically to have innocent murmurs. CONCLUSIONS: Despite the competency of the cardiologist, echocardiography diagnosed important but relatively uncommon cardiac abnormalities with prognostic implications that would have been missed if only the clinical examination was performed. Over and above the referring doctor's expectations for an echocardiogram to be performed is the need for the cardiologist to provide a complete and definitive diagnosis.

Preterm growth restriction and bronchopulmonary dysplasia: the vascular hypothesis and related physiology.

KEY POINTS: Approximately 5-10% pregnancies are affected by fetal growth restriction. Preterm infants affected by fetal growth restriction have a higher incidence of bronchopulmonary dysplasia. The present study is the first to measure pulmonary artery thickness and stiffness. The findings show that impaired vasculogenesis may be a contributory factor in the higher incidence of bronchopulmonary dysplasia in preterm growth restricted infants. The study addresses the mechanistic link between fetal programming and vascular architecture and mechanics. ABSTRACT: Bronchopulmonary dysplasia is the most common respiratory sequelae of prematurity and histopathologically features fewer, dysmorphic pulmonary arteries. The present study aimed to characterize pulmonary artery mechanics and cardiac function in preterm infants with fetal growth restriction (FGR) compared to those appropriate for gestational age (AGA) in the early neonatal period. This prospective study reviewed 40 preterm infants between 28 to 32 weeks gestational age (GA). Twenty infants had a birthweight <10th centile and were compared with 20 preterm AGA infants. A single high resolution echocardiogram was performed to measure right pulmonary arterial and right ventricular (RV) indices. The GA and birthweight of FGR and AGA infants were 29.8 ± 1.3 vs. 30 ± 0.9 weeks (P = 0.78) and 923.4 g ± 168 vs. 1403 g ± 237 (P < 0.001), respectively. Assessments were made at 10.5 ± 1.3 days after birth. The FGR infants had significantly thicker right pulmonary artery inferior wall (843.5 ± 68 vs. 761 ± 40 µm, P < 0.001) with reduced pulsatility (51.6 ± 7.6 µm vs. 59.7 ± 7.5 µm, P = 0.001). The RV contractility [fractional area change (28.7 ± 3.8% vs 32.5 ± 3.1%, P = 0.001), tricuspid annular peak systolic excursion (TAPSE) (5.2 ± 0.3% vs. 5.9 ± 0.7%, P = 0.0002) and myocardial performance index (0.35 ± 0.03 vs. 0.28 ± 0.02, P < 0.001)] was significantly impaired in FGR infants. Significant correlation between RV longitudinal contractility (TAPSE) and time to peak velocity/RV ejection time (measure of RV afterload) was noted (r2  =  0.5, P < 0.001). Altered pulmonary vascular mechanics and cardiac performance reflect maladaptive changes in response to utero-placental insufficiency. Whether managing pulmonary vascular disease will alter clinical outcomes remains to be studied prospectively.

Burnout: Can we help?

The recent editorial highlighting factors that may lead to burnout among the paediatric fraternity drew attention to those at most risk. They included 'intelligent, committed, single young women' more so then men and those who were 'high achievers with empathy who take the patients' problems to heart'. Yet little appears to be available to ameliorate the stresses experienced by clinicians while building their resilience and improving their understanding of the interactions between themselves and the patient/parents. Drawing on past experience, a psychologically orientated approach to clinical care is emphasised. This approach required greater knowledge of one's self together with the need to commune with like-minded colleagues. That led to a Balint-type weekly group led by a child psychiatrist where experiences were exchanged, new knowledge acquired and mutual support provided. That in turn led to further study and the acquisition of new skills, including ongoing supervision to achieve a therapeutic interview. The latter was facilitated by carefully listening to the patient/parent, recognising the hidden agenda, struggling with non-compliant parents and appreciating concepts such as transference and counter-transference as it related to the patient-doctor interaction. Such insights may help paediatricians improve their therapeutic effectiveness and increase their personal satisfaction, thus adding a bonus to the essential requirement of a knowledge-based diagnosis and management plan. Yet, only a few avenues are available to acquire such experiences, which need to be made available not only to those who recognise their importance but to all. How best to achieve these goals remains unresolved.

Educational DVD for parents of children with congenital heart disease - a pilot study.

Parental knowledge regarding their child's congenital heart defect (CHD) is limited. This study developed and evaluated an interactive DVD that helped parents to understand their child's CHD. A DVD describing four cardiac abnormalities was created using videos and Adobe Flash. The parents' knowledge was assessed via a questionnaire before and after receiving the DVD. A control group did not receive the DVD. The DVDs were successfully created and improved the parental knowledge of their child's cardiac anomaly. The pilot study suggests the need for further development of DVDs to describe additional abnormalities, whilst incorporating local management and outcomes.

Determinants of quality of life in adults with CHD: an Australian cohort.

BACKGROUND: Following improved survival rates in children with CHD, their quality of life and its determinants have become increasingly important. As part of a multicentre study entitled "Assessment of Patterns of Patient-Reported Outcomes in Adults with Congenital Heart Disease - International Study", this article reviews the relationships among quality of life, anxiety and depression, sense of coherence, and severity of disease in an Australian cohort of adults with CHD. Methods and results Adults with CHD were recruited from a single, community-based cardiology practice. All patients completed a self-reported questionnaire. A total of 135 patients, 71 males and 64 females, were recruited with a mean age of 26 years. The median quality of life in this cohort was 90; one-fifth of the patients experienced symptoms of anxiety. There was a significant negative correlation between quality of life and symptoms of anxiety and depression and a positive correlation between quality of life and sense of coherence. CONCLUSIONS: The quality of life of this cohort was generally excellent; however, one-fifth of them experienced symptoms of anxiety. Those with less anxiety and depression symptoms appeared to have a better quality of life, as did those who reported a higher sense of coherence. Interestingly, there was no significant relationship between complexity of CHD and quality of life.

A percutaneous fetal cardiac catheterization technique for pulmonary valvuloplasty and valvulotomy in a mid-gestation lamb model.

OBJECTIVE: We aimed to assess the feasibility of using a percutaneous transhepatic cardiac catheterization technique to perform fetal pulmonary valvuloplasty and valvulotomy under ultrasound guidance at mid-gestation. METHOD: In 13 mid-gestation fetal lambs without cardiac pathology, percutaneous transhepatic cardiac catheterization was used to position a coronary angioplasty catheter within the pulmonary valve. The balloon was inflated/deflated several times, simulating pulmonary valvuloplasty. In another two fetal lambs, a guidewire tip was positioned against the pulmonary valve, and unipolar diathermy was applied to simulate perforation of an atretic valve. RESULTS: Percutaneous access followed by right heart catheterization was successful in all cases. One fetus died following right ventricle perforation. Simulated pulmonary valvuloplasty was successful in nine cases using catheters with 6-mm-long balloons but unsuccessful in two cases (both survived) using 12-mm-long balloons. In one case, the catheter could not be inserted as the cannula became dislodged. Diathermy of the pulmonary valve was successful in both attempts. CONCLUSION: We successfully simulated in utero perforation and dilation of the pulmonary valve using percutaneous transhepatic access in fetal lambs. The technique has potential for clinical translation into treatment for human fetuses with critical pulmonary stenosis or pulmonary atresia with intact ventricular septum.

Cardiac function and arterial indices in infants born small for gestational age: analysis by speckle tracking.

AIM: To compare strain indices between small for gestational age (SGA) infants and asymptomatic appropriate for gestational age (AGA) infants and to ascertain correlations with arterial biophysical properties. METHODS: In this prospective observational echocardiographic study, 20 inborn term SGA infants weighing <3rd centile for gestational age were compared with 20 AGA infants. Demographic and echocardiographic data were analysed regarding cardiac strain and strain rate and arterial indices (stiffness, impedance and strain elastic modulus). Correlations between variables were assessed using Pearson's coefficient of correlation. RESULTS: Ponderal index was significantly lower in SGA infants (24.6 ± 2.9 vs. 29.5 ± 2.5). Left ventricular global longitudinal strain (GLS) was noted to be significantly impaired in the SGA infants (-15.9% ± 2.1 vs. -21.3% ± 2.8, p < 0.001). A basal to apical gradient was noted in segmental strain. Arterial biophysical measurements were significantly altered in the SGA infants. Significant correlations were noted between GLS and arterial stiffness (r = -0.4, p = 0.03), weight-indexed stiffness (r = -0.45, p = 0.02) and pressure-strain elastic modulus (r = -0.49, p = 0.01). CONCLUSION: Impairment in myocardial deformation was noted in the presence of altered arterial biophysical properties in the SGA infants.