Right Atrial Deformation in Predicting Outcomes in Pediatric Pulmonary Hypertension

Progress in the application of echocardiography in neonatal pulmonary hypertension

Purpose: This review aims to overview the use of echocardiography in diagnosing neonatal pulmonary hypertension, assessing cardiac function, and understanding the significance and limitations of various parameters in clinical practice.Materials and methods: Advancements in echocardiography for diagnosing and assessing neonatal pulmonary hypertension, evaluating cardiac function, monitoring treatment effectiveness, and predicting prognosis are discussed.Results: Echocardiography is a pivotal tool for diagnosing and managing neonatal pulmonary hypertension. It should be used with other ultrasound parameters to confirm findings and provide comprehensive analysis for improved accuracy.Conclusion: Understanding the value of echocardiography in neonatal pulmonary hypertension diagnosis and management is crucial. Its integration with other imaging modalities enhances diagnostic accuracy and improves patient outcomes.

A new staging system using right atrial strain in patients with immunoglobulin light-chain cardiac amyloidosis

AIMS

There are minimal data on the prognostic impact of right atrial strain during the reservoir phase (RASr) in patients with immunoglobulin light-chain (AL) cardiac amyloidosis.

METHODS AND RESULTS

Among 78 patients who were diagnosed with AL cardiac amyloidosis at Kumamoto University Hospital from 2007 to 2022, 72 patients with sufficient two-dimensional speckle tracking imaging data without chemotherapy before the diagnosis were retrospectively analysed. During a median follow-up of 403 days, 31 deaths occurred. Age and the rate of male sex were not significantly different between the all-cause death group and the survival group (age, 70.4 ± 8.8 years vs. 67.0 ± 10.0 years, P = 0.14, male sex, 65% vs. 66%, P = 0.91). The estimated glomerular filtration rate (eGFR) was significantly lower, and B-type natriuretic peptide (BNP) and high sensitivity cardiac troponin T (hs-cTnT) were significantly higher, in the all-cause death group versus the survival group (eGFR, 48.2 ± 21.0 mL/min/1.73 m2 vs. 59.4 ± 24.4 mL/min/1.73 m2, P < 0.05, BNP, 725 [360-1312] pg/mL vs. 123 [81-310] pg/mL, P < 0.01, hs-cTnT, 0.12 [0.07-0.18] ng/mL vs. 0.05 [0.03-0.08] ng/mL, P < 0.01). Left ventricular (LV) global longitudinal strain (GLS) (LV-GLS), left atrial strain during the reservoir phase (LASr), right ventricular GLS (RV-GLS), and RASr were significantly lower in the all-cause death group versus the survival group (LV-GLS, 8.5 ± 4.3% vs. 11.8 ± 3.8%, P < 0.01, LASr, 8.8 ± 7.1% vs. 14.3 ± 8.1%, P < 0.01, RV-GLS, 11.6 ± 5.1% vs. 16.4 ± 3.9%, P < 0.01, RASr, 10.2 ± 7.3% vs. 20.7 ± 9.5%, P < 0.01). RASr was significantly associated with all-cause death after adjusting for RV-GLS, LV-GLS and LASr (hazard ratio [HR]: 0.91, 95% confidence interval [95% CI]: 0.83-0.99, P < 0.05). RASr and log-transformed BNP were significantly associated with all-cause death after adjusting for log-transformed troponin T and eGFR (RASr, HR: 0.93, 95% CI: 0.87-1.00, P < 0.05; log-transformed BNP, HR: 2.10, 95% CI: 1.17-3.79, P < 0.05). The optimal cut-off values were RASr: 16.4% (sensitivity: 66%, specificity: 84%, area under curve [AUC]: 0.81) and BNP: 311.2 pg/mL (sensitivity: 83%, specificity: 78%, AUC: 0.82) to predict all-cause mortality using ROC analysis. Kaplan-Meier analysis revealed that patients with low RASr (<16.4%) or high BNP (>311.2 pg/mL) had a significantly high probability of all-cause death (both, P < 0.01). We devised a new staging score by adding 1 point if RASr decreased or BNP levels increased more than each cut-off value. The HR for all-cause death using score 0 as a reference was 5.95 (95% CI: 1.19-29.79; P < 0.05) for score 1 and 23.29 (95% CI: 5.37-100.98; P < 0.01) for score 2.

CONCLUSIONS

The new staging system using RASr and BNP predicted prognosis in patients with AL cardiac amyloidosis.

Right Atrial Strain in Pediatric Pulmonary Hypertension-A Prospective Observational Study

Right ventricular (RV) afterload due to elevated pulmonary arterial (PA) pressure in pulmonary hypertension (PH) causes long-term right atrial (RA) remodeling and dysfunction. RA function has been shown to correlate with PA pressures and outcome in both adult and pediatric patients with PH. We studied the role of RA strain in estimating PA pressures in congenital heart disease (CHD)-associated PH. Children below 12 years undergoing elective repair of CHD with left-to-right shunts and echocardiographic evidence of PH were included. RA reservoir, conduit and contractile strain along with conventional measures of RV function and PA pressure were measured using transthoracic echocardiography after induction of anaesthesia. Pre-and post-repair invasive PA pressures were measured after surgical exposure. 51 children with a median age of 24 months (range 4-144 months) were included, most of whom were undergoing VSD closure. Contractile RA strain showed good correlation with pre-repair systolic PA pressure in mmHg (r = 0.59, 95%CI 0.37-0.75) or expressed as a percentage of SBP (r = 0.67, 95%CI 0.49-0.80). It also predicted persistent postoperative PH as well as pre-repair pulmonary artery acceleration time and right ventricular systolic pressure measured from tricuspid regurgitation jet. The trends of correlation observed suggest a possible prognostic role of RA strain in ACHD with PH and potential utility in its echocardiographic assessment. The observed findings merit deeper evaluation in larger cohorts.

The Role of Echocardiography in the Diagnosis and Prognosis of Pulmonary Hypertension

The right heart catheterisation constitutes the gold standard for pulmonary hypertension (PH) diagnosis. However, echocardiography remains a reliable, non-invasive, inexpensive, convenient, and easily reproducible modality not only for the preliminary screening of PH but also for PH prognosis. The aim of this review is to describe a cluster of echocardiographic parameters for the detection and prognosis of PH and analyse the challenges of echocardiography implementation in patients with suspected or established PH. The most important echocardiographic index is the calculation of pulmonary arterial systolic pressure (PASP) through the tricuspid regurgitation (TR). It has shown high correlation with invasive measurement of pulmonary pressure, but several drawbacks have questioned its accuracy. Besides this, the right ventricular outflow track acceleration time (RVOT-AT) has been proposed for PH diagnosis. A plethora of echocardiographic indices: right atrial area, pericardial effusion, the tricuspid annular plane systolic excursion (TAPSE), the TAPSE/PASP ratio, tricuspid annular systolic velocity (s'), can reflect the severity and prognosis of PH. Recent advances in echocardiography with 3-dimensional right ventricular (RV) ejection fraction, RV free wall strain and right atrial strain may further assist the prognosis of PH.

Early cardiac function and death, severe bronchopulmonary dysplasia and pulmonary hypertension in extremely preterm infants

BACKGROUND

Association between early cardiac function and neonatal outcomes are scarcely reported. The aim of the current study was to describe this association with death, severe bronchopulmonary dysplasia (BPD) and BPD-related pulmonary hypertension (PH).

METHODS

Retrospective cohort study of infants <29 weeks born between 2015 and 2019. Infants with clinically acquired echocardiography at ≤21 days after birth were included and data were extracted by an expert masked to outcomes.

RESULTS

A total of 176 infants were included. Echocardiogram was performed at a median of 9 days (IQR 5-13.5). Of these, 31 (18%) had death/severe BPD and 59 (33.5%) had death/BPD-related PH. Infants with death/severe BPD were of lower birth weight (745 [227] vs 852 [211] grams, p = 0.01) and more exposed to invasive ventilation, late-onset sepsis, inotropes and/or postnatal steroids. Early echocardiograms demonstrated decreased right ventricular [Tricuspid Annular Plane Systolic Excursion: 5.2 (1.4) vs 6.2 (1.5) cm, p = 0.03] and left ventricular function [Ejection fraction 53 (14) vs 58 (10) %, p = 0.03]. Infants with death/BPD-related PH had an increased Eccentricity index (1.35 [0.20] vs 1.26 [0.19], p = 0.02), and flat/bowing septum (19/54 [35%] vs 20/109 [18%], p = 0.021).

CONCLUSIONS

In extremely premature infants, altered ventricular function and increased pulmonary pressure indices within the first 21 days after birth, were associated with the combined outcome of death/severe BPD and death/BPD-related PH.

IMPACT

Decreased cardiac function on echocardiography performed during first three weeks of life is associated with severe bronchopulmonary dysplasia in extremely premature infants. In extreme preterm infants, echocardiographic signs of pulmonary hypertension in early life are associated with later BPD-related pulmonary hypertension close to 36 weeks post-menstrual age. Early cardiac markers should be further studied as potential intervention targets in this population. Our study is adding comprehensive analysis of echocardiographic data in infants born below 29 weeks gestational age.

Mid-Systolic Notching of the Pulmonary Valve Doppler Signal is Highly Associated with Pulmonary Hypertension

Mid-systolic notching (MSN) of the pulmonary valve Doppler signal represents a reflected systolic pressure wave from the pulmonary vasculature and is often seen in pulmonary hypertension (PH). We hypothesize that MSN is associated with a higher pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (mPAP), and a diagnosis of PH in pediatric patients. This was a retrospective study of patients ≤ 18 years who had an echocardiogram obtained ≤ 30 days before catheterization for suspected PH. MSN was defined as an indentation in the initial two thirds of the systolic Doppler signal. PH was defined as mPAP > 20 mmHg and PVR ≥ 3.0 Wu  m2. Subgroups (MSN vs. normal) were compared. Receiver operator characteristic determined a continuous variable's discriminatory ability for a diagnosis of PH. Reproducibility of MSN was assessed. In total, 90 patients (73 with congenital heart disease) were included, of which 36 had MSN and 54 were normal. MSN patients were more likely to have PH, and had significantly higher mPAP, PVR, and lower pulmonary stroke volume. The presence of MSN had good discriminatory ability for PH diagnosis. The presence of MSN had high specificity (96%) for PH, whereas sensitivity was lower (54%). Reproducibility was 100% for MSN. MSN is a simple, highly reproducible echocardiographic metric associated with higher mPAP and PVR. When present, there is a high likelihood a diagnosis of PH confirmed by catheterization. Incorporation of MSN into imaging protocols may be useful. MSN appears worthy of further investigation in pediatric patients with suspected PH.

Evaluation of right atrial function by two-dimensional echocardiography and strain imaging in patients with RCA CTO recanalization

OBJECTIVES

The right heart is mainly supplied with blood by the right coronary artery (RCA). The impact of RCA chronic total occlusion (CTO) on the function of the right heart [right atrium (RA) and ventricle (RV)] and whether successful recanalization of a RCA CTO improves the function of the right heart is not clearly understood yet. We aimed to evaluate right atrial function after recanalization of the RCA using transthoracic echocardiography with additional strain imaging.

METHODS AND RESULTS

Fifty-five patients undergoing RCA CTO recanalization at the University Medical Center of Mainz were included in the study. Right atrial strain was assessed before and 6 months after successful CTO revascularization. The median age of the total collective was 66 (50-90) years. We did not find difference in our analysis of RA Volume (p 0.086), RA area (p 0.093), RA major dimension (p 0.32) and RA minor dimension (p 0.139) at baseline and follow-up. Mean RA reservoir strain at baseline was 30.9% (21.1-43.0) vs. 33.4% (20.7-47.7) at follow up (p < 0.001). Mean RA conduit strain was - 17.5% (- 10.7-(- 29.7)) at baseline vs. - 18.2% (- 9.6-(- 31.7)) at follow-up (p = 0.346). Mean RA contraction strain was - 12.9% (- 8.0- (- 21.3)) at baseline vs. - 15.5% (- 8.7-(- 26.6)) at follow-up (p < 0.001).

CONCLUSION

Right atrial function was altered in patients with RCA CTO. Successful revascularisation of an RCA CTO improved RA function assessed by strain imaging at follow-up.

Reference Values for Pediatric Atrial Volumes Assessed by Steady-State Free-Precession Magnetic Resonance Imaging Using Monoplane and Biplane Area-Length Methods

BACKGROUND

Measurement of atrial volumes by MRI is becoming increasingly important in pediatric cardiac disorders. However, MRI normal values for atrial volumes in children are lacking.

PURPOSE

To establish pediatric reference values for atrial volumes.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 155 healthy children from two large institutions (103 male, age 13.9 ± 2.8 years, range 4-18 years).

FIELD STRENGTH/SEQUENCE

A 1.5 T; balanced steady-state free precession (bSSFP) sequence.

ASSESSMENT

The monoplane and biplane area-length methods were used to measure minimal and maximal left and right atrial volumes (LAmin , LAmax , RAmin , and RAmax ) from four-chamber (4ch) and two-chamber (2ch) MR cine images. Centile charts and tables for atrial volumes were created.

STATISTICAL TESTS

Descriptive statistics, lambda-mu-sigma (LMS)-method of Cole and Green, univariable and multivariable linear regression models. A P value < 0.05 was considered to be statistically significant.

RESULTS

In the multivariable linear model, body surface area was significantly associated with all atrial volumes and sex was significantly associated with RA volumes, LA volumes measured in the 2ch-view as well as biplane LAmax. Average atrial volumes measured: monoplane 4ch: LAmin 13.1 ± 4.8 mL/m2 , LAmax 33.4 ± 8.8 mL/m2 , RAmin 18.5 ± 6.8 mL/m2 , RAmax 33.2 ± 9.6 mL/m2 ; monoplane 2ch: LAmin 12.7 ± 4.9 mL/m2 , LAmax 30.5 ± 9.5 mL/m2 ; biplane: LAmin 12.3 ± 4.5 mL/m2 , LAmax 30.9 ± 8.7 mL/m2 .

DATA CONCLUSION

Pediatric MRI reference values for atrial volumes have been provided.

TECHNICAL EFFICACY

2 EVIDENCE LEVEL: 4.

Prognostic value of right atrial strain derived from cardiovascular magnetic resonance in non-ischemic dilated cardiomyopathy

BACKGROUND

The value of right atrial (RA) function in cardiovascular diseases is currently limited. This study was to explore the prognostic value of RA strain derived from fast long axis method by cardiovascular magnetic resonance (CMR) in patients with non-ischemic dilated cardiomyopathy (DCM).

METHODS

We prospectively enrolled patients with DCM who underwent CMR from June 2012 to March 2019 and 120 age- and sex-matched healthy subjects. Fast long-axis strain method was performed to assess the RA phasic function including RA reservoir strain, conduit strain, and booster strain. The predefined primary endpoint was all-cause mortality. The composite heart failure (HF) endpoint included HF death, HF readmission, and heart transplantation. Cox regression analysis and Kaplan-Meier survival curve were performed to describe the association between RA strain and outcomes.

RESULTS

A total of 624 patients (444 men, mean 48 years) were studied. After a median follow-up of 32.5 months, 116 patients (18.6%) experienced all-cause mortality and 205 patients (32.9%) reached composite HF endpoint. RA function was impaired in DCM patients compared with healthy subjects (all P < 0.001). After adjustment for covariates, RA reservoir strain [hazard ratio (HR) (per 5% decrease) 1.19, 95% confidence interval (CI) 1.03-1.37, P = 0.022] and conduit strain [HR (per 5% decrease) 1.37, 95% CI 1.03-1.84, P = 0.033] were independent predictors of all-cause mortality. Moreover, RA strain added incremental prognostic value for the prediction of adverse cardiac events over baseline clinical and CMR predictors (all P < 0.05).

CONCLUSION

RA strain by fast long-axis analysis is independently associated with adverse clinical outcomes in patients with DCM.

TRIAL REGISTRATION

Trial registration number: ChiCTR1800017058; Date of registration: 2018-07-10 (Retrospective registration); URL: https://www.

CLINICALTRIALS

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Right atrial function early after tetralogy of Fallot repair

Diastolic dysfunction after repair for Tetralogy of Fallot (TOF) is associated with adverse long-term outcomes. Right atrial (RA) mechanics as a proxy of right ventricular (RV) diastolic function in the early post-operative period after surgical repair for TOF has not been reported. We sought to evaluate RA and RV strain prior to hospital discharge after TOF repair and to identify important patient factors associated with strain using a machine learning method. Single center retrospective cohort study of TOF patients undergoing surgical repair, with analysis of RA and RV strain from pre-and post-operative echocardiograms. RA function was assessed by the peak RA strain, systolic RA strain rate, early diastolic RA strain rate and RA emptying fraction. RV systolic function was measured by global longitudinal strain. Pre- and post-operative values were compared using Wilcoxon rank sum test. Gradient boosted machine (GBM) models were used to identify the most important predictors of post-operative strain. In total, 153 patients were enrolled, median age at TOF repair 3.5 months (25th-75th percentile: 2.2- 5.2), mostly male (67%), and White (64.1%). From pre-to post-operative period, there was significant worsening in all RA parameters and in RV strain. GBM models identified patient, anatomic, and surgical factors that were strong predictors of post-operative RA and RV strain. These factors included pulmonary valve and branch pulmonary artery Z scores, birth weight, gestational age and age at surgery, pre-operative RV fractional area change and oxygen saturation, type of outflow tract repair, duration of cardiopulmonary bypass, and early post-operative partial arterial pressure of oxygen. There is significant worsening in RA and RV strain early after TOF repair, indicating early alteration in diastolic and systolic function after surgery. Several patient and operative factors influence post-operative RV function. Most of the factors described are not readily modifiable, however they may inform pre-operative risk-stratification. The clinical application of RA strain and the prognostic implication of these early changes merit further study.

Relation of Right Atrial Strain to Mortality in Infants With Single Right Ventricles

We explored associations of surveillance testing in infants with single right ventricle (sRV) physiology with clinical outcomes. This prospective, single-center study included patients with sRV who had initial palliative surgery (September 2019 to December 2020). Echocardiograms and B-type naturetic peptide (BNP) obtained as a pair within 24 hours as part of clinical care were included. The primary outcome was death/heart transplant. Secondary outcomes included interstage duration of milrinone use, hospital length of stay, and no digoxin use. sRV functional assessment (subjective grade, fractional area change, tricuspid annular plane systolic excursion, global longitudinal strain, right atrial strain [RAS]) was performed offline. Associations between echocardiography, BNP, and clinical outcomes were determined. Of 26 subjects (47 encounters), 20 had hypoplastic left heart syndrome (77%). Median age at data collection was 50 days (interquartile range 26 to 90). In most encounters (73%), sRV function was subjectively normal. Median BNP was 332 pg/ml (interquartile range 160 to 1,085). A total of 5 patients (19%) met the primary outcome and had lower RAS (14.1 vs 21.3, p = 0.038), but all other parameters were similar to transplant-free survivors. RAS (16.1%, 0.83) had the highest area under curve, followed by global longitudinal strain (-14.4%, 0.77). Higher RAS was associated with fewer days on milrinone (coefficient -1.37, 95% confidence interval [CI] -2.54 to -0.20, p = 0.02) and higher odds of digoxin use (odds ratio 1.09, 95% CI 1.01 to 1.18, p = 0.047). Higher BNP was only associated with a lower odds of digoxin use (odds ratio 0.69, 95% CI 0.5 to 0.96, p = 0.03). In conclusion, RAS is a potentially important imaging marker in infants with sRV and merits further investigation in larger studies.

Echocardiographic Assessment of Right Ventricular Function in Paediatric Heart Disease: A Practical Clinical Approach

As the right ventricle (RV) plays an integral role in different paediatric heart diseases, the accurate assessment of RV size and function is essential in the diagnosis, management, and prognostication of congenital and acquired cardiac lesions. Yet, echocardiographic evaluation of the RV is challenging because of its complex and variable morphology, its different physiology compared with the left ventricle, and its capability to adapt to different loading conditions associated with congenital and acquired heart diseases within certain ranges. Reliable echocardiographic detection of RV systolic and diastolic dysfunction remains challenging while important for patient management. This review provides an updated, practical approach to assessing RV function in structurally normal hearts and in children with common congenital heart defects and in those with pulmonary hypertension. We also review the impact of tricuspid valve function on RV functional parameters. There is no single functional RV parameter that uniquely describes RV function; instead a combination of different parameters is recommended in clinical practice. Qualitative and quantitative analysis of RV function will be reviewed including more recent techniques such as speckle tracking and 3D echocardiography.

Right Atrial Strain in Preterm Infants With a History of Bronchopulmonary Dysplasia

BACKGROUND

Few studies have utilized right atrial (RA) strain to evaluate right ventricular (RV) diastolic dysfunction in preterm infants with bronchopulmonary dysplasia (BPD). We aimed to evaluate the associations of RA strain with BPD severity and respiratory outcomes in preterm infants with BPD.

METHODS

We retrospectively studied 153 infants with BPD born before 32 weeks of gestational age at CHA Bundang Medical Center. Peak longitudinal right atrial strain (PLRAS) was obtained using velocity vector imaging and compared among infants across BPD severity. Conventional echocardiographic parameters and clinical characteristics were also evaluated.

RESULTS

In infants with severe BPD, mean gestational age (27.4 ± 2.1 weeks) and mean birth weight (971.3 ± 305.8 g) were significantly smaller than in those with mild BPD (30.0 ± 0.9 weeks, 1,237.3 ± 132.2 g) and moderate BPD (29.6 ± 1.3 weeks, 1,203.2 ± 214.4 g). PLRAS was significantly lower in infants with severe BPD (26.3 ± 10.1%) than in those in the moderate BPD group (32.4 ± 10.9%) or mild BPD group (31.9 ± 8.3%). Tricuspid E/e′ and maximum RA volume index were similar across BPD severity. A decrease in PLRAS was significantly correlated with increased duration of mechanical ventilation duration; however, tricuspid E/e′ and maximum RA volume index were not.

CONCLUSIONS

Evaluating PLRAS with other parameters in infants with BPD might detect RV diastolic dysfunction. Longer follow-up and larger study populations may elucidate the association between PLRAS and respiratory outcomes in infants with BPD.

Temporal trends in right heart strain in patients undergoing pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension

BACKGROUND

Pulmonary thromboendarterectomy (PTE) is a curative procedure for chronic thromboembolic pulmonary hypertension (CTEPH). Right ventricular free wall strain (RV FWS) and right atrial strain (RAS) are not well studied in a CTEPH population. We sought to determine temporal trends in RAS and RV FWS in patients post-PTE.

METHODS

28 patients undergoing PTE for CTEPH were prospectively enrolled in a surgical database. Comprehensive echocardiographic assessment of the right heart was performed including RV FWS, right atrial volume, and the three components of RAS: reservoir, conduit, and booster strain.

RESULTS

Patients undergoing PTE demonstrated improvement in NYHA functional class (P < 0.001). Hemodynamic assessment showed improvement in mean pulmonary artery pressure from 49.7 ± 8.5 mm Hg to 23.9 ± 6.5 mm Hg (P < 0.001) and pulmonary vascular resistance decreased from 7.8 ± 3.2 wu to 2.4 ± 1.3 wu (P < 0.001). Tricuspid annular plane systolic excursion (TAPSE) and lateral S` declined immediately post-op. RV FWS improved from -14.4 ± 4% to -19 ± 3.4% post-op and -21.2 ± 4.7% at long-term follow-up (P < 0.001). Improvement in RV FWS post-op was driven primarily by increases in the apical and mid segments. RA volume declined significantly during the study period. RA reservoir and conduit strain improved after PTE.

CONCLUSION

Patients undergoing PTE for CTEPH had significant improvement in right heart hemodynamics immediately post-op. Traditional echo metrics of RV performance including TAPSE and lateral S` did not improve. RV FWS improved, which was driven by changes in the apical and mid segments. This highlights that RV FWS is a viable and useful metric to follow in CTEPH patients post-PTE.

A guide to echocardiographic assessment in children and adolescents with pulmonary hypertension

While the current definition of pulmonary hypertension (PH) is still based on haemodynamic variables, transthoracic echocardiography is the most important diagnostic clinical tool for the first assessment and evaluation of a patient, in whom PH is suspected. In addition, it is the most important clinical modality in long term follow-up and the utility of echocardiography has widely been demonstrated in patients with PH. Echocardiography not only reveals the underlying cardiac morphology and diagnosis of any associated cardiac defects. In most patients with PH right ventricular (RV) pressure estimation is feasible. In addition, ventricular systolic and diastolic function, as well as ventricular-ventricular interactions of both ventricles can be assessed by using echocardiography. Maximizing the use of echocardiography by reporting several measures to gain information and quantitatively describe the parameters, that are linked to prognosis, seem particularly appealing in these children, in whom other advanced imaging modalities requiring anaesthesia is associated with a considerable risk. Herein we provide a practical approach and a concise and clinically applicable echocardiographic guidance and present basic variables, which should be obtained at any assessment. Moreover, we present additional advanced echocardiographic measures, that can be applied in a research or clinical setting when progressive PH needs a deeper insight to assess heart function, estimation of pulmonary artery pressures among others, by echocardiography. Finally, clinically relevant studies in view of the prognostic properties with a focus on the most important echocardiographic variables in pediatric PH are summarized.

Role of cardiovascular magnetic resonance in pediatric pulmonary hypertension-novel concepts and imaging biomarkers

Pulmonary hypertension (PH) in children is a heterogenous disease of the small pulmonary arteries characterized by a progressive increase in pulmonary vascular resistance. Despite adequate medical therapy, long-term pressure overload is frequently associated with a progressive course leading to right ventricular failure and ultimately death. Invasive hemodynamic assessment by cardiac catheterization is crucial for initial diagnosis, risk stratification and therapeutic strategy. Although echocardiography remains the most important imaging modality for the assessment of right ventricular function and pulmonary hemodynamics, cardiovascular magnetic resonance (CMR) has emerged as a valuable non-invasive imaging technique that enables comprehensive evaluation of biventricular performance, blood flow, morphology and the myocardial tissue. In this review, we summarize the principles and applications of CMR in the evaluation of pediatric PH patients and present an update about novel CMR based concepts and imaging biomarkers that may provide further diagnostic, therapeutic and prognostic information.

Update on pediatric pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) causes high morbidity and mortality in children. In this review, we discuss advances in diagnosis and treatment of this disorder.

RECENT FINDINGS

Proceedings published from the 2018 World Symposium updated the definition of pulmonary hypertension to include all adults and children with mean pulmonary artery pressure more than 20 mmHg. Targeted PAH therapy is increasingly used off-label, but in 2017, bosentan became the first Food and Drug Administration-targeted PAH therapy approved for use in children.

SUMMARY

In recent years, advanced imaging and clinical monitoring have allowed improved risk stratification of pulmonary hypertension patients. New therapies, approved in adults and used off-label in pediatric patients, have led to improved outcomes for affected children.

Short-Term Effects of Inhaled Nitric Oxide on Right Ventricular Flow Hemodynamics by 4-Dimensional-Flow Magnetic Resonance Imaging in Children With Pulmonary Arterial Hypertension

Background

Pulmonary arterial hypertension (PAH) manifests with progressive right ventricular (RV) dysfunction, which eventually impairs the left ventricular function. We hypothesized that 4‐dimensional–flow magnetic resonance imaging can detect flow hemodynamic changes associated with efficient intracardiac flow during noninvasive inhaled nitric oxide (iNO) challenge in children with PAH.

Methods and Results

Children with PAH (n=10) underwent 2 same‐day separate iNO challenge tests using: (1) 4‐dimensional–flow magnetic resonance imaging and (2) standard catheterization hemodynamics. Intracardiac flow was evaluated using the particle tracking 4‐flow component analysis technique evaluating the direct flow, retained inflow, delayed ejection flow, and residual volume. Respective flow hemodynamic changes were compared with the corresponding catheterization iNO challenge results. The RV analysis revealed decreased direct flow in patients with PAH when compared with controls (P<0.001) and increase in residual volume (P<0.001). Similarly, the left ventricular analysis revealed decreased direct flow in patients with PAH when compared with controls (P=0.004) and increased proportion of the residual volume (P=0.014). There was an increase in the RV direct flow during iNO delivery (P=0.009), with parallel decrease in the residual volume (P=0.008).

Conclusions

Children with PAH have abnormal biventricular flow associated with impaired diastolic filling. The flow efficiency is significantly improved in the RV on iNO administration with no change in the left ventricle. The changes in the RV flow have occurred despite the minimal change in catheterization hemodynamics, suggesting that flow hemodynamic evaluation might provide more quantitative insights into vasoreactivity testing in PAH.

The Prognostic Value of Right Atrial Strain Imaging in Patients with Precapillary Pulmonary Hypertension

BACKGROUND

Right ventricular (RV) failure in patients with pulmonary hypertension (PH) is associated with unfavorable clinical events and a poor prognosis. Elevation of right atrial (RA) pressure is established as a marker for RV failure. However, the additive prognostic value of RA mechanical function is unclear.

METHODS

The authors tested the hypothesis that RA function by strain echocardiography has prognostic usefulness by studying 165 consecutive patients with precapillary PH defined invasively: mean pulmonary artery pressure ≥ 25 mm Hg and pulmonary capillary wedge pressure < 15 mm Hg. Speckle-tracking strain analyses of the right atrium and right ventricle were performed, along with routine measures. Peak RA strain values from six segments using generic speckle-tracking software were averaged to RA peak longitudinal strain, representing RA global reservoir function. The primary end point was all-cause mortality during 5 years of follow-up. RA strain was similarly analyzed in a control group of 16 normal subjects for comparison.

RESULTS

There were 151 patients with PH (mean age, 55 ± 16 years; 73% women; mean World Health Organization functional class, 2.6 ± 0.6), after 14 exclusions (three with atrial septal defects and 11 with left ventricular ejection fractions < 50%). RA strain measurement was feasible in 93% of patients and RV strain measurement in 88%. RA peak longitudinal strain was significantly reduced in patients with PH compared with control subjects, as expected (P < .001). During 5-year follow-up, 73 patients (48%) died. Patients with RA peak strain in the lowest quartile (<25%) had a significant risk for death (P = .006), even after correcting for confounding variables. RA strain was independently associated with survival in multivariate analysis (P = .039) and had additive prognostic value to RV strain (log-rank P = .01) in subgroup analysis.

CONCLUSIONS

RA peak longitudinal strain had additive prognostic usefulness to other clinical measures, including RV strain, RA area, and RA pressure, in patients with PH. RA mechanical function by strain imaging has potential for clinical applications in patients with PH.

Right ventricular area strain from 3-dimensional echocardiography: Mechanistic insight of right ventricular dysfunction in pediatric pulmonary hypertension

BACKGROUND

Right ventricular (RV) function is a major contributor to the outcome of pulmonary arterial hypertension (PAH). Adult studies demonstrated that regional and global changes in RV deformation are prognostic in PAH using 3-dimensional echocardiography (3DE). However, regional and global dynamic changes in RV mechanics have not been described in pediatric PAH. We compared 3DE RV regional and global deformation between pediatric patients who had associated PAH with congenital heart disease (APAH-CHD), pediatric patients who had idiopathic PAH (IPAH), and normal controls, and evaluated the clinical outcomes.

METHODS

A total of 48 controls, 47 patients with APAH-CHD, and 45 patients with IPAH were evaluated. 3DE RV sequences were analyzed and post-processed to extract global and regional deformation (circumferential, longitudinal, and area strain). Statistical analyses compared the sub-groups on the basis of global and regional deformation, and outcome analysis was performed.

RESULTS

Patients with PAH had significantl8y different global and regional deformation (p < 0.001) compared with controls. Patients with APAH-CHD and and those with IPAH significantly differed in global circumferential strain (p < 0.010), area strain (inlet septum, p = 0.041), and circumferential strain at the inlet septum (p < 0.019), apex free wall (p < 0.004), and inlet free wall (p < 0.004). Circumferential strain at the inlet free wall and circumferential, longitudinal, and area strain at the apex free wall were predictors of adverse events.

CONCLUSIONS

RV regional and global strain differ between controls and pediatric patients with PAH. RV apical free-wall area strain provides insight into the mechanism of RV dysfunction in pediatric patients with PAH, with regional strain emerging as outcome predictors, suggesting that this novel measure may be considered as a future measure of RV function.

Longitudinal assessment of right atrial conduit fraction provides additional insight to predict adverse events in pediatric pulmonary hypertension

BACKGROUND

Recent studies show adverse right atrial (RA) emptying pattern is prognostic for clinical worsening events in pediatric pulmonary arterial hypertension (PAH). No study has reported changes in RA emptying over time or evaluated whether serial measurements offer further prognostic information.

METHODS

Prospective study of 32 children with idiopathic or heritable PAH undergoing echocardiogram at baseline and 1-year. RA conduit fraction percent (RA cF%) was measured as percentage of total diastolic RA area change prior to the electrical p wave. Clinical worsening was analyzed with a predefined composite adverse event outcome.

RESULTS

Longitudinal subjects (median age 13.3 yr) had RA cF% 61% (IQR 32-68%) at baseline and 60% (IQR 35-73%) at 1-year (NS). 11 subjects had a qualifying event during median 21-month follow-up. Subjects with an event had 1-year RA cF% = 33% (IQR 20-40%) compared to 72% (IQR 63-75%) for those with no event (p < 0.001). Event rates were lowest for subjects with both echocardiograms showing RA cF% > 60% (0%), highest for subjects with neither (80%), and intermediate for those with one (38%, p = 0.003).

CONCLUSIONS

Changes in RA cF% inform risk of adverse events in pediatric PAH. This finding supports the role of RA cF% as both a prognostic biomarker and potential treatment target.

Echocardiography for the Assessment of Pulmonary Hypertension and Congenital Heart Disease in the Young

While invasive assessment of hemodynamics and testing of acute vasoreactivity in the catheterization laboratory is the gold standard for diagnosing pulmonary hypertension (PH) and pulmonary vascular disease (PVD) in children, transthoracic echocardiography (TTE) serves as the initial diagnostic tool. International guidelines suggest several key echocardiographic variables and indices for the screening studies when PH is suspected. However, due to the complex anatomy and special physiological considerations, these may not apply to patients with congenital heart disease (CHD). Misinterpretation of TTE variables can lead to delayed diagnosis and therapy, with fatal consequences, or–on the other hand-unnecessary invasive diagnostic procedures that have relevant risks, especially in the pediatric age group. We herein provide an overview of the echocardiographic workup of children and adolescents with PH with a special focus on children with CHD, such as ventricular/atrial septal defects, tetralogy of Fallot or univentricular physiology. In addition, we address the use of echocardiography as a tool to assess eligibility for exercise and sports, a major determinant of quality of life and outcome in patients with PH associated with CHD.

Assessing the atria in pediatric sickle cell disease: Beyond the dilation

BACKGROUND

Diastolic dysfunction (DD) and pulmonary hypertension (PH) are common causes of mortality for sickle cell disease (SCD) patients in developed countries. We hypothesized that left and right atrial strain (LAS-Ɛ, RAS-rƐ) are decreased in SCD adolescents, and that worsening values correlate with laboratory markers of disease severity.

METHODS

Prospective cohort study of patients with HbSS genotype of SCD was compared with healthy controls. LAS and RAS were measured from 4- and 2-chamber views by a blinded reader. Peak strain and strain rate values were obtained for atrial contraction (ac), reservoir (res), and conduit (con) phases. Mitral/tricuspid Doppler velocities, left atrial volume, right atrial area were obtained. Laboratory variables were obtained from the electronic record with the three prior values being averaged. Differences in variables were assessed with Wilcoxon rank sum test, and correlations assessed with Spearman's coefficient.

RESULTS

There were 33 SCD patients compared to 35 healthy controls of similar age, gender, and size. SCD patients had increased left atrial volume and right atrial area. For LAS, Ɛres was significantly lower in SCD patients. For RAS, RƐcon was significantly lower. Neither measurement correlated with clinical markers. The majority of SCD patients had relatively normal atrial strain values. Those with markedly lower values had similar atrial size.

CONCLUSIONS

A sub-set of SCD patients have markedly low Ɛres and rƐcon. No correlation with clinical markers was identified. Larger, longitudinal studies may determine utility of atrial strain as a screening tool in this at-risk population.

Cardiovascular disease in young People with Type 1 Diabetes: Search for Cardiovascular Biomarkers

Premature onset of cardiovascular disease is common in people with type 1 diabetes and is relatively understudied in youth. Several reports in adolescents and young adults with diabetes demonstrate evidence of arterial stiffness and cardiac dysfunction, yet critical gaps exist in our current understanding of the temporal progression of cardiac and vascular dysfunction in these youth, and mechanistic investigations with robust pathophysiologic assessment are lacking. This review attempts to summarize relevant cardiovascular studies concerning children, adolescents, and young adults with type 1 diabetes. We focus on imaging-based biomarkers routinely applied to youth and adults that are well-established in their ability to predict adjudicated cardiovascular outcomes, and their relevant physiologic interpretation. Particularly, we focus the attention to 1) cardiac ventricular strain imaging techniques which are known to be predictive of clinical outcomes in patients with heterogenous causes of heart failure, and 2) stiffness in large arteries, a well-established prognostic marker of cardiovascular events. We conclude that there remains an urgent need for sensitive and quantitative biomarkers to define the natural history of cardiac and vascular disease origination and progression in type 1 diabetes, and set the stage for interpreting interventional studies focused on preventing, reversing or slowing disease progression.

Update on noninvasive imaging of right ventricle dysfunction in pulmonary hypertension

Pulmonary hypertension (PH) is a progressive disease affecting patients across the life span. The pathophysiology primarily involves the pulmonary vasculature and right ventricle (RV), but eventually affects the left ventricular (LV) function as well. Safe, accurate imaging modalities are critical for diagnosis, serial monitoring, and tailored therapy. While cardiac catheterization remains the conventional modality for establishing diagnosis and serial monitoring, noninvasive imaging has gained considerable momentum in providing accurate assessment of the entire RV-pulmonary axis. In this state-of-the-art review, we will discuss the most recent developments in echocardiography, magnetic resonance imaging, and computed tomography in PH evaluation from pediatric to adult population.

Altered Biatrial Phasic Function after Heart Transplantation in Children

PURPOSE

We used two-dimensional echocardiographic speckle-tracking to investigate whether left and right atrial (LA and RA) phasic function in pediatric heart transplantation (HT) patients is altered and explored the relationship to HT-related clinical variables.

METHODS

Eighty-six subjects (36 HT and 50 normal children) were prospectively enrolled in two centers. Clinical data included age at HT, bypass time, ischemia time, donor age, and incidence of rejection. Atrial deformation indices including strain and strain rates (SRs) were measured using two-dimensional echocardiographic speckle-tracking. Components of phasic atrial function-reservoir (ε_r, SR_r), conduit (ε_cd, SR_cd), and booster (ε_ct, SR_ct) were calculated. Comparisons with controls were made using t test or Kruskal-Wallis test, and correlations to clinical variables were explored.

RESULTS

The mean age and body surface area of HT subjects were 10.2 ± 6.2 years and 1.2 ± 0.6 m², respectively. The mean heart rates were higher in HT (96 ± 18 vs 88 ± 21 in controls). There were reductions in RA and LA reservoir (ε_r, SR_r), conduit (ε_cd, SR_cd), and booster (ε_ct, SR_ct) function in HT compared with controls. There was no relationship of LA and RA deformation indices with mean age at HT, bypass time, or ischemia time. The LA ε_cd correlated weakly with donor age (r = -0.49, P = .04) and RA SR_r, and SR_cd showed association with duration of HT (P < .05). Nineteen HT recipients had follow-up studies 0.24 ± 0.18 years after the first examination, and deformational indices were not significantly changed.

CONCLUSIONS

Atrial strain determination is feasible in pediatric HT recipients and demonstrates disruption of reservoir, conduit, and booster function of both atria in this population; we speculate this may be a consequence of ventricular diastolic dysfunction.

Flow profile characteristics in Fontan circulation are associated with the single ventricle dilation and function: principal component analysis study

The Fontan circulation is characterized as a nonpulsatile flow propagation without a pressure-generating ventricle. However, flow through the Fontan circulation still exhibits oscillatory waves as a result of pressure changes generated by the systemic single ventricle. Identification of discrete flow patterns through the Fontan circuit may be important to understand single ventricle performance. Ninety-seven patients with Fontan circulation underwent phase-contrast MRI of the right pulmonary artery, yielding subject-specific flow waveforms. Principal component (PC) analysis was performed on preprocessed flow waveforms. Principal components were then correlated with standard MRI indices of function, volume, and aortopulmonary collateral flow. The first principal component (PC) described systolic versus diastolic-dominant flow through the Fontan circulation, accounting for 31.3% of the variance in all waveforms. The first PC correlated with end-diastolic volume (R = 0.34, P = 0.001), and end-systolic volume (R = 0.30, P = 0.003), cardiac index (R = 0.51, P < 0.001), and the amount of aortopulmonary collateral flow (R = 0.25, P = 0.027)-lower ventricular volumes and a smaller volume of collateral flow-were associated with diastolic-dominant cavopulmonary flow. The second PC accounted for 19.5% of variance and described late diastolic acceleration versus deceleration and correlated with ejection fraction-diastolic deceleration was associated with higher ejection fraction. Principal components describing the diastolic flow variations in pulmonary arteries are related to the single ventricle function and volumes. Particularly, diastolic-dominant flow without late acceleration appears to be related to preserved ventricular volume and function, respectively.NEW & NOTEWORTHY The exact physiological significance of flow oscillations of phasic and temporal flow variations in Fontan circulation is unknown. With the use of principal component analysis, we discovered that flow variations in the right pulmonary artery of Fontan patients are related to the single ventricle function and volumes. Particularly, diastolic-dominant flow without late acceleration appears to be related to more ideal ventricular volume and systolic function, respectively.

Right ventricular function correlates of right atrial strain in pulmonary hypertension: a combined cardiac magnetic resonance and conductance catheter study

The functional relevance of right atrial (RA) function in pulmonary hypertension (PH) remains incompletely understood. The purpose of this study was to explore the correlation of cardiac magnetic resonance (CMR) feature tracking-derived RA phasic function with invasively measured pressure-volume (P-V) loop-derived right ventricular (RV) end-diastolic elastance ( Eed) and RV-arterial coupling [ratio of end-systolic elastance to arterial elastance ( Ees/ Ea)]. In 54 patients with severe PH, CMR was performed within 24 h of diagnostic right heart catheterization and P-V measurements. RA phasic function was assessed by CMR imaging of RA reservoir, passive, and active strain. The association of RA phasic function with indexes of RV function was evaluated by Spearman’s rank correlation and linear regression analyses. Median [interquartile range] RA reservoir strain, passive strain, and active strain were 19.5% [11.0–24.5], 7.0% [4.0–12.0], and 13.0% [7.0–18.5], respectively. Ees/ Ea was 0.73 [0.48–1.08], and Eed was 0.14 mmHg/mL [0.05–0.22]. RV diastolic impairment [RV end-diastolic pressure (EDP) and Eed] was correlated with RA phasic function, but Ea and Ees were not. In addition, RA phasic function was correlated with inferior vena cava diameter. In multivariate linear regression analysis, adjusting for key P-V loop indexes, Eed and EDP remained significantly associated with RA phasic function. We conclude that RA phasic function is altered in relation to impaired diastolic function of the chronically overloaded right ventricle and contributes to backward venous flow and systemic congestion. These results call for more attention to RA function in the management of patients with PH.

NEW & NOTEWORTHY There is growing awareness of the importance of the right atrial (RA)-right ventricular (RV) axis in pulmonary hypertension (PH). Our results uncover alterations in RA phasic function that are related to depressed RV lusitropic function and contribute to backward venous return and systemic congestion in chronic RV overload. Assessment of RA function should be part of the management and follow-up of patients with PH.

Impaired myocardial deformation and ventricular vascular coupling in obese adolescents with dysglycemia

Background

It is unknown that dysglycemia in obese adolescents has effects on myocardial deformation that are more pronounced when compared to obesity alone. We hypothesized that obesity associated abnormal glucose tolerance (dysglycemia) would have adverse effects on two-dimensional speckle tracking echocardiography derived longitudinal, radial and circumferential strain (LS, RS, CS) compared to age and gender lean controls. We also examined if changes in deformation would be reflected in abnormal ventricular vascular coupling indices (VVI).

Methods

In a prospective cross-sectional design 39 obese adolescents (15.9 ± 1.7 years; 101.5 ± 39 kg; female − 58%) were compared to age and gender matched lean controls (15.7 ± 1.8 yrs, 60 ± 12.8 kg). Based on results from an oral glucose tolerance test (OGTT), obese adolescents were categorized as obese normoglycemic (ONG, n = 25) or obese dysglycemic (ODG, n = 14). Left ventricular (LV) global and average LS, CS, RS and strain rate were measured. LV ejection fraction and mass index were measured and VVI approximated as ratio of arterial elasticity (Ea) and end-systolic elastance (Ees).

Results

Adolescents with ODG had significantly (P = 0.005) impaired global LS (− 20.98% ± 2.8%) compared to controls (− 23.01% ± 2.3%). A similar (P = 0.0027) reduction was observed in average LS for adolescents with ODG (18.87% ± 2.5%) compared to controls (20.49% ± 2%). Global CS was also decreased (P = 0.03) in ODG (− 23.95%) compared to ONG (− 25.80). A similar trend was observed in average CS after multivariate regression for BMI and blood pressure. CS correlated with HbA1c in both groups (P = 0.05). VVI had a negative correlation with both LS (r = − 0.4, P = 0.025) and CS rate (r = − 0.36, P = 0.04).

Conclusions

Myocardial strain and strain rate were significantly altered in obese adolescents. Unfavorable subclinical reductions in global and average CS were more pronounced in adolescents with dysglycemia compared to obese adolescents with normoglycemia and controls. These data indicate progressive worsening of subendocardial function across the spectrum of glucose tolerance. Strain rate was predictive of VVI in obese adolescents, suggesting strain rate may be a sensitive marker for cardiac remodeling in abnormal glucose homeostasis states.

Right atrial function in pediatric heart transplant patients by echocardiographic strain measurements

BACKGROUND

CAV is a major cause of mortality in PHTx patients. Research on echocardiographic indices to detect CAV focuses primarily on ventricular function and less is known about RAF. Thus, we primarily sought to evaluate RAF in PHTx patients with CAV. For secondary analysis, we compared RAF between PHTx patients and control patients and evaluated RAF with respect to rejection and surgical type.

METHODS

We retrospectively evaluated echocardiography derived RA strain indices in recipients <18 years old and >1 year from time of transplant. The RA strain phases included, reservoir (εs), conduit (εe), pump (εa), and respective strain rate indices (SRs, SRe, SRa).

RESULTS

There were 36 PHTx patients and 14 age-, sex-matched control patients. There was a significant reduction in εs, εe, SRs, and SRe (P < 0.001) in the PHTx patients when compared to controls. There was no difference between the CAV (+) and CAV (-) patients with respect to RAF indices. Furthermore, εs, εe, and SRe (P < 0.05) were lower in patients with acute rejection (n = 7) compared to those without (n = 26). Patients with a bi-atrial anastomosis (n = 14) had decreased εs, εa, SRs, SRa (P < 0.05), compared to bi-caval anastomosis (n = 24).

CONCLUSION

PHTx patients have decreased RAF compared to healthy children. RAF does not differentiate PHTx patients based on the presence of CAV. RAF is also decreased in PHTx patients with rejection and in those transplanted with a bi-atrial anastomosis.

EXPRESS: Statement on imaging and pulmonary hypertension from the Pulmonary Vascular Research Institute (PVRI)

Pulmonary hypertension (PH) is highly heterogeneous and despite treatment advances it remains a life-shortening condition. There have been significant advances in imaging technologies, but despite evidence of their potential clinical utility, practice remains variable, dependent in part on imaging availability and expertise. This statement summarizes current and emerging imaging modalities and their potential role in the diagnosis and assessment of suspected PH. It also includes a review of commonly encountered clinical and radiological scenarios, and imaging and modeling-based biomarkers. An expert panel was formed including clinicians, radiologists, imaging scientists, and computational modelers. Section editors generated a series of summary statements based on a review of the literature and professional experience and, following consensus review, a diagnostic algorithm and 55 statements were agreed. The diagnostic algorithm and summary statements emphasize the key role and added value of imaging in the diagnosis and assessment of PH and highlight areas requiring further research.

Differences in pulmonary arterial flow hemodynamics between children and adults with pulmonary arterial hypertension as assessed by 4D-flow CMR studies

Despite different developmental and pathological processes affecting lung vascular remodeling in both patient populations, differences in 4D MRI findings between children and adults with PAH have not been studied. The purpose of this study was to compare flow hemodynamic state, including flow-mediated shear forces, between pediatric and adult patients with PAH matched by severity of pulmonary vascular resistance index (PVRi). Adults (n = 10) and children (n = 10) with PAH matched by pulmonary vascular resistance index (PVRi) and healthy adult (n = 10) and pediatric (n = 10) subjects underwent comprehensive 4D-flow MRI to assess peak systolic wall shear stress (WSS_max) measured in the main (MPA), right (RPA), and left pulmonary arteries (LPA), viscous energy loss (E_L) along the MPA-RPA and MPA-LPA tract, and qualitative analysis of secondary flow hemodynamics. WSS_max was decreased in all pulmonary vessels in children with PAH when compared with the same age group (all P < 0.05). Similarly, WSS_max was decreased in all pulmonary vessels in adult PAH patients when compared with healthy adult subjects (all P < 0.01). Average E_L was increased in adult patients with PAH when compared with the same age group along both MPA-RPA (P = 0.020) and MPA-LPA (P = 0.025) tracts. There were no differences in E_L indices between adults and pediatric patients. Children and adult patients with PAH have decreased shear hemodynamic forces. However, pathological flow hemodynamic formations appear to be more consistent in adult patients, whereas flow hemodynamic abnormalities appear to be more variable in children with PAH for comparable severity of PVRi.

NEW & NOTEWORTHY Both children and adult patients with PAH have decreased shear hemodynamic forces inside the pulmonary arteries associated with the degree of vessel dilation and stiffness. These differences also exist between healthy normotensive children and adults. However, pathological flow hemodynamic formations appear to more uniform in adult patients, whereas in children with PAH flow, hemodynamic abnormalities appear to be more variable. Pathological flow formations appear not to have a major effect on viscous energy loss associated with the flow conduction through proximal pulmonary arteries.

Noninvasive wave intensity analysis predicts functional worsening in children with pulmonary arterial hypertension

The purpose of the present study was to characterize pulmonary vascular stiffness using wave intensity analysis (WIA) in children with pulmonary arterial hypertension (PAH), compare the WIA indexes with catheterization- and MRI-derived hemodynamics, and assess the prognostic ability of WIA-derived biomarkers to predict the functional worsening. WIA was performed in children with PAH ( n = 40) and healthy control subjects ( n = 15) from phase-contrast MRI-derived flow and area waveforms in the main pulmonary artery (MPA). From comprehensive WIA spectra, we collected and compared with healthy control subjects forward compression waves (FCW), backward compression waves (BCW), forward decompression waves (FDW), and wave propagation speed ( c-MPA). There was no difference in the magnitude of FCW between PAH and control groups (88 vs. 108 mm⁵·s^-1·ml^-1, P = 0.239). The magnitude of BCW was increased in patients with PAH (32 vs. 5 mm⁵·s^-1·ml^-1, P < 0.001). There was no difference in magnitude of indexed FDW (32 vs. 28 mm⁵·s^-1·ml^-1, P = 0.856). c-MPA was increased in patients with PAH (3.2 vs. 1.6 m/s, P < 0.001). BCW and FCW correlated with mean pulmonary arterial pressure, right ventricular volumes, and ejection fraction. Elevated indexed BCW [heart rate (HR) = 2.91, confidence interval (CI): 1.18-7.55, P = 0.019], reduced indexed FDW (HR = 0.34, CI: 0.11-0.90, P = 0.030), and increased c-MPA (HR = 3.67, CI: 1.47-10.20, P = 0.004) were strongly associated with functional worsening of disease severity. Our results suggest that noninvasively derived biomarkers of pulmonary vascular resistance and stiffness may be helpful for determining prognosis and monitoring disease progression in children with PAH. NEW & NOTEWORTHY Wave intensity analysis (WIA) studies are lacking in children with pulmonary arterial hypertension (PAH) partially because WIA, which is necessary to assess vascular stiffness, requires an invasive pressure-derived waveform along with simultaneous flow measurements. We analyzed vascular stiffness using WIA in children with PAH who underwent phase-contrast MRI and observed significant differences in WIA indexes between patients with PAH and control subjects. Furthermore, WIA indexes were predictive of functional worsening and were associated with standard catheterization measures.