The assessment of atrial function in single ventricle hearts from birth to Fontan: a speckle-tracking study by using strain and strain rate

Common atrial reservoir strain during the interstage period is a predictor of poor outcomes prior to Fontan completion in hypoplastic left heart syndrome

BACKGROUND

The atrium augments ventricular function, but the significance of atrial function in hypoplastic left heart syndrome (HLHS) has not been well evaluated.

OBJECTIVE

We investigated the association of atrial reservoir strain (common atrial strain [CAS]) to death or need for transplantation in patients with HLHS.

METHODS

In this retrospective single-center study, echocardiograms from three timepoints (pre-stage 1 palliation [S1P], 4-8 weeks post-S1P, and pre-Glenn) were analyzed in infants with classic HLHS. Patients were separated based on transplant-free survival to Fontan (survivors) versus death or heart transplant prior to Fontan (composite outcome). Echocardiographic parameters evaluated included CAS, right ventricle (RV) global longitudinal strain (RVGLS), RV fractional area change (FAC), and tricuspid annular plane systolic excursion (TAPSE). An equal variance t-test, regression, and receiver operating characteristic (ROC) analyses were performed.

RESULTS

A total of 45 HLHS patients (25 survivors, 20 patients meeting endpoint) were included in this study. There were no significant differences in any of the functional parameters during the pre-stage 1 or post-stage 1 timepoints. Pre-Glenn CAS and RVGLS were significantly worse in those meeting composite endpoint compared to survivors. CAS was significantly correlated to RVGLS during the pre-S1P and pre-Glenn timepoints. A pre-Glenn CAS < 19.5 had an area under the curve of  .78 and a 75% sensitivity and 83% specificity for death or need for transplantation.

CONCLUSION

Pre-Glenn CAS is significantly lower in patients with mortality or need for the transplantation prior to Fontan completion and may carry prognostic significance in patients with HLHS.

Comparison of cardiac function between single left ventricle and tricuspid atresia: assessment using echocardiography combined with computational fluid dynamics

Patients with single left ventricle (SLV) and tricuspid atresia (TA) have impaired systolic and diastolic function. However, there are few comparative studies among patients with SLV, TA and children without heart disease. The current study includes 15 children in each group. The parameters measured by two-dimensional echocardiography, three-dimensional speckle tracking echocardiography (3DSTE), and vortexes calculated by computational fluid dynamics were compared among these three groups. Twist is best correlated with ejection fraction measured by 3DSTE. Twist, torsion, apical rotation, average radial strain, peak velocity of systolic wave in left lateral wall by tissue Doppler imaging (sL), and myocardial performance index are better in the TA group than those in the SLV group. sL by tissue Doppler imaging in the TA group are even higher than those in the Control group. In patients with SLV, blood flow spreads out in a fan-shaped manner and forms two small vortices. In the TA group, the main vortex is similar to the one in a normal LV chamber, but smaller. The vortex rings during diastolic phase are incomplete in the SLV and TA groups. In summary, patients with SLV or TA have impaired systolic and diastolic function. Patients with SLV had poorer cardiac function than those with TA due to less compensation and more disordered streamline. Twist may be good indicator for LV function.

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.

Echocardiographic Assessment of Atrial Function: From Basic Mechanics to Specific Cardiac Diseases

The left and right atria serve as buffer chambers to control the flow of venous blood for ventricular filling. If an atrium is absent, blood does not flow effectively into the ventricle, leading to venous blood retention and low cardiac output. The importance of atrial function has become increasingly recognized, because left atrial (LA) function contributes to cardiac performance, and loss of LA function is associated with heart failure. LA volume change has been used for LA function assessment in experimental and clinical studies. In conjunction with LA pressure, the LA pressure–volume relationship provides a better understanding of LA mechanics. LA strain measurement by speckle tracking echocardiography was introduced to evaluate three components of LA function as a (booster) pump, reservoir and conduit. Furthermore, increasing evidence supports the theory that LA reservoir strain has prognostic utility in various cardiac diseases. In this review, we summarize LA contribution to maintain cardiac performance by evaluating LA function with echocardiography according to our experiences and previous reports. Furthermore, we discuss LA dysfunction in challenging cardiac diseases of cardiac amyloidosis and adult congenital heart disease.

Feasibility, Reproducibility and Reference Ranges of Left Atrial Strain in Preterm and Term Neonates in the First 48 h of Life

Left atrial strain (LAS) is the most promising technique for assessment of diastolic dysfunction but few data are available in neonates. Our aim was to assess feasibility and reproducibility, and to provide reference ranges of LAS in healthy neonates in the first 48 h of life. We performed one echocardiography in 30 neonates to assess feasibility and develop a standard protocol for image acquisition and analysis. LAS reservoir (LASr), conduit (LAScd) and contraction (LASct) were measured. We performed echocardiography at 24 and 48 h of life in an unrelated cohort of 90 neonates. Median (range) gestational age and weight of the first cohort were 34.4 (26.4–40.2) weeks and 2075 (660–3680) g. LAS feasibility was 96.7%. Mean (SD) gestational age and weight of the second cohort were 34.2 (3.8) weeks and 2162 (833) g. Mean (SD) LASr significantly increased from 24 to 48 h: 32.9 (3.2) to 36.8 (4.6). Mean (SD) LAScd and LASct were stable: −20.6 (8.0) and −20.8 (9.9), −11.6 (4.9) and −13.5 (6.4). Intra and interobserver intraclass correlation coefficient for LASr, LAScd and LASct were 0.992, 0.993, 0.986 and 0.936, 0.938 and 0.871, respectively. We showed high feasibility and reproducibility of LAS in neonates and provided reference ranges.

Atrial function in the Fontan circulation: comparison with invasively assessed systemic ventricular filling pressure

Abnormal atrial mechanics in biventricular circulations have been associated with elevated left heart filling pressures. Similar associations in the Fontan circulation are unknown. The aim of this study was to examine the relationship between atrial mechanics and invasively assessed hemodynamic parameters late after the Fontan operation. Thirty-nine Fontan patients with echocardiographic and invasive hemodynamic studies done within 48 h were included and were compared to 40 age-matched healthy controls. Atrial and ventricular strain measurements were measured offline using 2-dimensional speckle-tracking. Mean age was 10.2 ± 6.7 years and 24 (62%) were male. Atrial strain measures were lower in Fontan patients compared to healthy controls. There was no significant association between atrial strain measurements and Fontan systemic ventricular filling pressures (SVFP) as indicated by pulmonary artery occlusion pressures, direct left atrial pressure or systemic ventricular end-diastolic pressure. Global atrial strain was not correlated with segmental atrial strain in the pulmonary venous atrium. Global atrial reservoir strain was positively correlated with pulmonary vascular resistance (r = 0.508, p = 0.045). Global atrial conduit strain was positively correlated with E/A ratio of the AV valve inflow (r = 0.555, p = 0.002). Atrial and ventricular strain measurements were not significantly correlated. In patients with a Fontan, global atrial function is significantly depressed, and is uncoupled from segmental left lateral atrial function. Global as well as segmental atrial mechanics are not significantly associated with SVFPs in Fontan patients. Instead, global atrial reservoir function appears to parallel pulmonary vascular resistance.

A hybrid therapy for arrhythmogenic congestive cavity in a single ventricle

We describe a 15-year-old girl who underwent intraoperative catheter ablation for the ventricular tachycardia associated with Ebstein's anomaly with functional pulmonary atresia and a small right ventricle (RV) after Fontan surgery. The computed tomography showed the dilated right atrium and RV due to the failure of RV plication. The activation mapping revealed that the ventricular tachycardia showed a focal pattern originating from the atrialized RV (aRV). With careful preparations, the procedure of catheter ablation combined with the adjustment of Starnes fenestration and plication of RV/atrialized RV was very effective for this patient.

Dobutamine stress testing for the evaluation of atrial and diastolic ventricular function in Fontan patients

Objective

To assess the atrial and ventricular diastolic function response to dobutamine stress in Fontan patients, and to relate these measurements to exercise capacity and events during the follow-up.

Methods

We performed a secondary analysis of a cross-sectional multicentre study of Fontan patients with intra-atrial lateral tunnel (ILT) or extracardiac conduit (ECC) modification. Subjects underwent cardiac MRI during rest and low-dose dobutamine stress, and cardiopulmonary exercise testing. Atrial and diastolic ventricular function parameters were derived from volume-time curves.

Medical records were abstracted for a composite end-point of death, listing for transplant, arrhythmia and reintervention. Spearman’s r correlation tests and Cox proportional hazards models were used to assess the relation between the dobutamine response for atrial and diastolic ventricular function and outcomes, including exercise capacity.

Results

We included 57 patients (26 ECC; 31 ILT) aged 12.8 (IQR (10.3–15.5)) years. During dobutamine stress atrial cyclic volume change increased (3.0 (0.4–5.9) mL/m², p<0.001), as did early (1.9 (−1.6 to 3.6) mL/m², p=0.001) and late emptying volume (2.2 (0.2–4.4) mL/m², p<0.001).

Ventricular early filling decreased (−1.6 (−5.7 to 0.7) mL/m², p=0.046) and ventricular late filling increased (1.0 (−0.4 to 3.4) mL/m², p<0.001) while stroke volume remained similar.

Only for patients with the ECC modification, atrial early emptying volume increase correlated with peak oxygen uptake (ρ=0.66, p=0.002). No other parameter related to exercise capacity.

During a median 7.1-year follow-up, 22 patients reached the composite endpoint. No parameter predicted events during the follow-up.

Conclusions

Dobutamine stress augmented atrial reservoir and pump function for Fontan patients. Atrial early emptying reserve related to exercise capacity in ECC patients. No other atrial or diastolic ventricular function parameter related to outcomes.

Atrial Reservoir Strain is Associated with Decreased Cardiac Index and Adverse Outcomes Post Fontan Operation

Fontan patients rely on atrial function for diastolic filling and to augment cardiac output. Emerging data suggests that diminished atrial function is predictive of poor outcomes in adults but studies evaluating the association between atrial mechanics in Fontan patients and outcomes are lacking. We sought to assess atrial function in Fontan patients using speckle tracking echocardiography to determine whether atrial function is associated with invasive hemodynamics and clinical outcomes. Single-center review of Fontan patients receiving both catheterization and echocardiogram from 2012-2017. Atrial reservoir, conduit and pump global longitudinal strain and strain rate were assessed by speckle tracking echocardiography. The primary outcome was a composite of all adverse clinical outcomes including cardiac hospitalizations, transplant and death. Eighty-three Fontan patients at a median age of 14.2 years (IQR 8.6, 21.7) at time of echocardiogram were included. Increased atrial reservoir strain (p = 0.04), atrial emptying fraction (p = 0.04) and atrial fractional area change (p = 0.04), were associated with higher cardiac index at baseline. There were no associations between atrial strain and systemic ventricular end diastolic pressure (EDP) at catheterization. Reservoir strain was inversely associated with the composite clinical outcome on multivariable Cox proportional hazard analysis (HR 0.96, p = 0.03). Reduced atrial function is associated with reduced cardiac index, but is not directly associated with ventricular EDP in Fontan patients. Reservoir strain is associated with an excess of adverse clinical outcomes in Fontan patients.

The Influence of Atrial Strain on Functional Capacity in Patients with the Fontan Circulation

Speckle-tracking echocardiography has been used to assess atrial function. This analysis is feasible in univentricular hearts. The aim of this study was to characterize the relationship between atrial strain and functional capacity in the Fontan circulation. Apical four-chamber echocardiographic loops of 39 Fontan patients were reviewed. The dominant atrium was assessed for active (ε_act), conduit (ε_con), and reservoir (ε_res) strain and ε_act/ε_res ratio. Cardiopulmonary exercise test was performed on the same day and oxygen uptake (VO₂) at ventilatory threshold (VT) and peak VO₂ were chosen as the dependent variables. Statistical analysis was performed using SPSS^® version 23. Unpaired t test was used for binomial and continuous variable correlation; single and multivariable linear regression were used for continuous variable correlation. Statistical significance was defined as p value < 0.05. VO₂ at VT as a percentage of predicted VO₂ was 36.8% (SD 10.7). Peak VO₂ was 64.7% (SD 18.9) of the predicted value. In univariate analysis, both were associated with age, atrioventricular regurgitation, ejection fraction, ε_res, ε_con, and ε_act/ε_res. In multivariate regression, higher VO₂ at VT and peak VO₂ were associated with younger age (p = 0.003 and p = 0.001, respectively) and higher ε_con (p = 0.026 and p = 0.020). Evaluation of heart function is difficult in the Fontan circulation, hindered by complex ventricular morphology and lack of normative data. VO₂ provides a good surrogate. Atrial strain parameters are compromised in these patients and associated with VO₂. Therefore, whenever possible, atrial strain should be measured as it may provide a new method of risk stratification.

Speckle-Tracking Echocardiography for the Assessment of Atrial Function during Fetal Life

INTRODUCTION

Speckle-tracking echocardiography has become a major tool in the evaluation of heart function. Atrial strain has emerged as an important component in the assessment of cardiac function, but there is a paucity of prenatal data. The aim of this study was to describe our initial experience of measurement of atrial strain in fetuses, with respect to both feasibility and the strain patterns observed.

METHODS

Four-chamber Digital Imaging and Communications in Medicine loops were acquired prospectively for deformation imaging. Fifty-three normal fetuses with no morphologic or functional abnormalities were selected for analysis. The three strain components of atrial cycle for both left atrium (LA) and right atrium (RA) were acquired-reservoir (LAres or RAres), conduit, and contraction (LAct or RAct)-and are expressed as a percentage. Ratios of these components were calculated. Simple linear regression was used to analyze how the dependent variables changed according to gestational age and frame rate.

RESULTS

The median gestational age was 30 weeks (range, 23-35), and the frame rate was 74 frames per second (fps; range, 35-121). Left atrial strain was feasible in 48/53 (91%), and right atrial strain in 46/53 (87%) of cases. The onset of LA contraction could be identified on the strain curves in 32 of 48 (67%) cases, and of the RA in 17 of 46 (37%) cases. The values of RAres and RAct were higher compared with those of LAres and LAct (33.9% vs 30.3%, P = .014; and 21.5% vs 16.8%, P = .005), and the contraction:reservoir ratio was also higher for RA (0.63 vs 0.55 for LA, P = .003). Higher values for LAres, LAct, RAres, and RAct were associated with higher frame rate (P = .007, .020, .049, and .012, respectively). The onset of LA contraction was better identified with a higher frame rate (mean 77 vs 59 fps when not seen, P = .007). A higher LA contraction:reservoir ratio was associated with a lower gestational age (P = .042).

CONCLUSION

Measurement of atrial strain is feasible in the fetal heart. The values are influenced by gestational age and frame rate, so it is necessary to account for these variables. Comparison of left versus right atrial strain values contrasts with those observed postnatally. Atrial function merits further study during fetal life, to aid understanding of maturational changes and disease states.

Cardiac magnetic resonance derived atrial function in patients with a Fontan circulation

To assess atrial function in Fontan patients using cardiac MRI (CMR) and determine the relationships between atrial function, hemodynamics, and clinical outcomes. Two center chart review identified all Fontan patients with technically adequate CMR to assess atrial function within 1 year of cardiac catheterization and age-matched controls with CMR. Atrial reservoir, conduit, and pump global longitudinal strain and strain rate measurements were determined by CMR. Univariate and stepwise multivariable analysis were conducted to detect associations of atrial function measures with ventricular end diastolic pressure (EDP), cardiac index (CI), exercise capacity, liver stiffness and a composite outcome of heart transplantation, ventricular assist device or death. The study cohort was comprised of 33 Fontan patients and 30 age-matched controls. Fontan patients had lower atrial reservoir and conduit strain, and lower reservoir, conduit, and pump strain rate compared to age-matched controls. Atrial conduit strain was negatively associated with EDP and lower atrial pump-to-conduit strain ratio was associated with lower cardiac index in multivariable analysis. Lower atrial pump strain was associated with lower exercise capacity (per 1% increase: β = 2.3 ± 0.9, p = 0.03) and higher liver stiffness (per 1% increase: β =  - 0.12 ± 0.03, p = 0.002). Higher atrial pump strain (HR per 1% increase = 0.53 [95% confidence interval 0.22, 0.83], p = 0.002) and ventricular ejection fraction (HR per 1% increase = 0.90 [95% confidence interval 0.80, 0.98], p = 0.02) were associated with lower risk for the composite adverse outcome. Atrial function is impaired in Fontan patients and is associated with worse CI, EDP, exercise performance, liver stiffness, and a higher risk for adverse outcomes.

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.

Atrial Function and Its Role in the Non-invasive Evaluation of Diastolic Function in Congenital Heart Disease

Diastolic dysfunction has correlated with adverse outcomes in various forms of unrepaired and repaired or palliated congenital heart disease (CHD). The non-invasive assessment of diastolic function in pediatric and adult patients with CHD remains challenging. Atrial size has a pivotal role in the evaluation of diastolic function; however, a growing body of evidence supports the additional role of atrial function as a more sensitive parameter of ventricular diastolic dysfunction. While the importance of atrial function is becoming clearer in adult acquired heart disease, it remains ambiguous in those with CHD. In this review we set the stage with the current understanding of diastolic function assessment in CHD, followed by insight into atrial form and function including its non-invasive assessment, and conclude with the current knowledge of atrial function in CHD. A general pattern of decrease in reservoir and conduit function with compensatory increase followed by decompensatory decrease in contractile function seems to be the common pathway of atrial dysfunction in most forms of CHD.

Influence of maternal aerobic exercise during pregnancy on fetal cardiac function and outflow

BACKGROUND

Risk factors for cardiovascular disease, the leading cause of death, have been documented in children as young as 3 years of age. Maternal environment (eg, exercise) influences fetal development and long-term health. Thus, the development of the fetal cardiovascular system during pregnancy is likely a preliminary indicator of cardiac health at birth and a proxy for the future risk of cardiovascular disease throughout life.

OBJECTIVE

The purpose of this study was to assess the effects of supervised prenatal aerobic exercise at recommended levels on fetal cardiac function and outflow in the third trimester of pregnancy. We hypothesized that fetuses of aerobically trained women compared with fetuses of nonexercising women would exhibit increased cardiac function and greater cardiac output.

STUDY DESIGN

Secondary data analyses of a 20-week, randomized controlled exercise intervention trial in pregnant women between 2015 and 2018 in Eastern North Carolina were performed. Eligibility criteria included pregnant women <16 weeks gestation, singleton pregnancy, aged 18-40 years, body mass index of 18.5-34.99 kg/m², physician clearance letter for exercise participation, reliable transportation, and method of communication. Exclusion criteria included the presence of chronic conditions (eg, type 1 or 2 diabetes mellitus), current medications known to adversely affect fetal growth (eg, antidepressants), alcohol, smoking, or illicit drug use. The patient cohort consisted of 133 eligible pregnant women who were assigned randomly to either an aerobic exercise (n=66) group that participated in 150 minutes of supervised, moderate-intensity (40-59% VO_2peak; 12-14 on Borg Rating of Perceived Exertion) aerobic exercise per week or a nonexercising group (n=61) that consisted of 150 minutes per week of light (<40% VO_2peak) stretching and relaxation breathing techniques. Between 34 and 36 weeks gestation, a fetal echocardiogram was performed to assess fetal cardiac function, which included fetal heart rate, right- and left-ventricular stroke volume, stroke volume index, cardiac output, cardiac output index, and cardiac outflow that included pulmonary and aortic valve diameters, peak flow velocity, and peak flow velocity-time integral. Fetal activity state (quiet vs active) during the echocardiogram and maternal aerobic capacity served as covariates. Intention-to-treat and per-protocol (participants who attended ≥80% of exercise sessions) analysis of covariance regression models were performed.

RESULTS

Of the 127 randomly assigned participants, 66 and 50 participants were included in the intention-to-treat and per-protocol analyses, respectively. Prenatal aerobic exercise significantly increased fetal right-ventricular cardiac measures of right ventricular stroke volume (P=.001) and stroke index via velocity-time integral (P=.003), right ventricular cardiac output (P=.002), cardiac index via velocity-time integral (P=.006), pulmonary artery diameter (P=.02), and pulmonary valve velocity-time integral (P=.03). Only in the intention-to-treat analysis was a significant difference in fetal left ventricular cardiac outflow observed; there was a greater aortic valve peak velocity (P=.04) found among fetuses of aerobically trained pregnant women. No other statistically significant between-group differences were found.

CONCLUSION

The findings of this study demonstrate that participation in prenatal aerobic exercise at recommended levels may improve fetal cardiac function and outflow parameters. Follow-up cardiovascular measures in the postnatal period are needed to determine potential long-term effects on the offspring's cardiac function and outflow.

Atrial function in Fontan patients assessed by CMR: Relation with exercise capacity and long-term outcomes

OBJECTIVE

To assess the role of atrial function on exercise capacity and clinical events in Fontan patients.

DESIGN

We included 96 Fontan patients from 6 tertiary centers, aged 12.8 (IQR 10.1-15.6) years, who underwent cardiac magnetic resonance imaging and cardiopulmonary exercise testing within 12 months of each other from 2004 to 2017. Intra-atrial lateral tunnel (ILT) and extracardiac conduit (ECC) patients were matched 1:1 with regard to age, gender and dominant ventricle. The pulmonary venous atrium was manually segmented in all phases and slices. Atrial function was assessed by volume-time curves. Furthermore, atrial longitudinal and circumferential feature tracking strain was assessed. We determined the relation between atrial function and exercise capacity, assessed by peak oxygen uptake and VE/VCO₂ slope, and events (mortality, listing for transplant, re-intervention, arrhythmia) during follow-up.

RESULTS

Atrial maximal and minimal volumes did not differ between ILT and ECC patients. ECC patients had higher reservoir function (21.1 [16.4-28.0]% vs 18.2 [10.9-22.2]%, p = .03), lower conduit function and lower total circumferential strain (13.8 ± 5.1% vs 18.0 ± 8.7%, p = .01), compared to ILT patients. Only for ECC patients, a better late peak circumferential strain rate predicted better VE/VCO₂ slope. No other parameter of atrial function predicted peak oxygen uptake or VE/VCO₂ slope. During a median follow-up of 6.2 years, 42 patients reached the composite end-point. No atrial function parameters predicted events during follow-up.

CONCLUSIONS

ECC patients have higher atrial reservoir function and lower conduit function. Atrial function did not predict exercise capacity or events during follow-up.

Pathophysiology, adaptation, and imaging of the right ventricle in Fontan circulation

The Fontan procedure, which creates a total cavopulmonary anastomosis and represents the final stage of palliation for hypoplastic left heart syndrome, generates a unique circulation relying on a functionally single right ventricle (RV). The RV pumps blood in series around the systemic and pulmonary circulation, which requires adaptations to the abnormal volume and pressure loads. Here, we provide a complete review of RV adaptations as the RV assumes the role of the systemic ventricle, the progression of RV dysfunction to a distinct pattern of heart failure unique to this disease process, and the assessment and management strategies used to protect and rehabilitate the failing RV of Fontan circulation.

Left Atrial Size and Function in Patients With Congenital Aortic Valve Stenosis

Little information exists on left atrial (LA) function in healthy children and in patients with congenital aortic valve stenosis (AS). We sought to determine whether patients with significant congenital AS have detectable abnormalities in LA size and function compared with matched normal controls. Retrospective chart review and analysis of 2-dimensional echocardiographic images for phasic left atrial volumes (LAVs) and longitudinal LA strain by speckle tracking in children ≥1 years of age with ≥ moderate isolated congenital AS. LAVs and LA strain in AS cases were compared with age, gender, and body surface area-matched controls (healthy children with a normal echocardiogram). Between June 2004 and October 2012, there were 36 eligible AS cases [age 13 (range 3 to 27) years; 30 males] with a median maximal Doppler gradient of 63 (range 43 to 94) mm Hg. No significant interobserver and intraobserver differences were noted in the analyses of normal subjects. Significantly higher phasic body surface area-adjusted LAVs [preatrial contraction: p = 0.01; minimal: p = 0.04] and higher LA contractile function parameters [indexed active LA stroke volume: p = 0.03; peak negative strain p = 0.04] were noted in AS cases compared with matched controls. In conclusion, compared with normal, children with congenital AS have higher preatrial contraction and minimal phasic LA volumes and higher LA contractile function.

The continuing challenge of evaluating diastolic function by echocardiography in children: developing concepts and newer modalities

PURPOSE OF REVIEW

Assessment of diastolic function by echocardiography is challenging but important. Left ventricular filling has been more extensively studied than the right ventricle, and predominantly in adult populations. Although multiple parameters exist to assess diastolic function, they all have limitations, including load and heart rate dependency, which make assessment of diastolic function particularly challenging. The purpose of this article is to review evolving concepts and modalities for echo assessment of diastolic function in children.

RECENT FINDINGS

The paradigm whereby diastolic dysfunction severity progresses in a staged fashion from impaired relaxation to increasing ventricular stiffness, may not apply in children. In addition, previous adult guidelines are not readily applicable to children with cardiomyopathy and the applicability of the newly revised adult guidelines needs to be evaluated in children. It is unlikely that any one single echocardiographic diastolic parameter will adequately reflect diastolic function. Hence, parameters derived from atrioventricular valve inflow, pulmonary venous, and tissue Doppler need to be integrated. Newer modalities such as diastolic strain rate and rotation mechanics may be useful as more sensitive markers of early ventricular dysfunction but have important limitations and require more evaluation before routine use in practice. Assessment of systolic-diastolic coupling may enhance assessment of diastolic function.

SUMMARY

Diastolic function impacts outcomes and should be part of routine echocardiographic assessment of function. An integrative approach combining different parameters, possibly with contribution of newer modalities in the future, is required.

Right atrial mechanics provide useful insight in pediatric pulmonary hypertension

Right atrial (RA) mechanics have been studied infrequently in children in the past due to technical constraints. With the advent of strain imaging, RA physiology can now be studied in greater detail. The principal aim of this study was to describe functional changes in right heart mechanics of children with idiopathic pulmonary arterial hypertension (PAH), by using new applications of RA strain. In this retrospective study, we evaluated RA mechanics of 20 patients (age range = 3-23 years) with PAH and 18 control patients. RA longitudinal strain (RALS) and longitudinal displacement (LD) were calculated by speckle-tracking echocardiography. RALS was plotted against LD, producing a characteristic strain-displacement (S-D) loop. Standard indices of right heart function and right heart catheterization data were obtained. Patients were clinically subdivided into "compensated" and "decompensated" PAH. A chart review was performed to identify patients who subsequently developed adverse outcomes, including death, awaiting or received lung and/or heart transplantation. RALS was significantly lower in decompensated PAH compared with both controls and compensated PAH. Area enclosed by S-D loops differed significantly between the compensated and decompensated PAH subgroups (5.33 [3.90-9.44] versus 1.83 [1.17-2.36], P < 0.05). S-D loop area and RALS possessed high sensitivity and specificity compared to other parameters for identifying children with PAH who subsequently developed adverse outcomes. In particular, their sensitivities and specificities were greatly superior compared to those of tricuspid annular plane systolic excursion (TAPSE). RALS may represent a useful metric for assessing right ventricular (RV) dysfunction. S-D loops, composed over an entire cardiac cycle, may present useful, composite information regarding both systolic and diastolic right heart function. RA mechanics may serve as useful tools for identifying patients with more severe PAH, who are at risk for future adverse outcomes associated with RV failure.

Right Atrial Deformation in Predicting Outcomes in Pediatric Pulmonary Hypertension

BACKGROUND

Elevated right atrial (RA) pressure is a risk factor for mortality, and RA size is prognostic of adverse outcomes in pulmonary hypertension (PH). There is limited data on phasic RA function (reservoir, conduit, and pump) in pediatric PH. We sought to evaluate (1) the RA function in pediatric PH patients compared with controls, (2) compare the RA deformation indices with Doppler indices of diastolic dysfunction, functional capacity, biomarkers, invasive hemodynamics, and right ventricular functional indices, and (3) evaluate the potential of RA deformation indices to predict clinical outcomes.

METHODS AND RESULTS

Sixty-six PH patients (mean age 7.9±4.7 years) were compared with 36 controls (7.7±4.4 years). RA and right ventricular deformation indices were obtained using 2-dimensional speckle tracking (2DCPA; TomTec, Germany). RA strain, strain rates, emptying fraction, and right ventricular longitudinal strain were measured. RA function was impaired in PH patients versus controls (P<0.001). There were significant associations between RA function with invasive hemodynamics (P<0.01). RA reservoir, pump function, the rate of RA filling, and atrial minimum volume predicted adverse clinical outcomes (hazard ratio [HR], 0.15; confidence interval [CI], 0.03-0.73; P<0.01; HR, 0.05; CI, 0.003-0.43; P<0.004; HR, 0.04; CI, 0.006-0.56; P<0.01; and HR, 8.6; CI, 1.6-37.2; P<0.01, respectively).

CONCLUSIONS

RA deformation properties are significantly altered in pediatric PH patients. Progressive worsening of RA reservoir and conduit functions is related to changes in right ventricular diastolic dysfunction. RA reservoir function, pump function, the rate of atrial filling, and atrial minimum volume emerged as outcome predictors in pediatric PH.

Patient-specific parameter estimation in single-ventricle lumped circulation models under uncertainty

Computational models of cardiovascular physiology can inform clinical decision-making, providing a physically consistent framework to assess vascular pressures and flow distributions, and aiding in treatment planning. In particular, lumped parameter network (LPN) models that make an analogy to electrical circuits offer a fast and surprisingly realistic method to reproduce the circulatory physiology. The complexity of LPN models can vary significantly to account, for example, for cardiac and valve function, respiration, autoregulation, and time-dependent hemodynamics. More complex models provide insight into detailed physiological mechanisms, but their utility is maximized if one can quickly identify patient specific parameters. The clinical utility of LPN models with many parameters will be greatly enhanced by automated parameter identification, particularly if parameter tuning can match non-invasively obtained clinical data. We present a framework for automated tuning of 0D lumped model parameters to match clinical data. We demonstrate the utility of this framework through application to single ventricle pediatric patients with Norwood physiology. Through a combination of local identifiability, Bayesian estimation and maximum a posteriori simplex optimization, we show the ability to automatically determine physiologically consistent point estimates of the parameters and to quantify uncertainty induced by errors and assumptions in the collected clinical data. We show that multi-level estimation, that is, updating the parameter prior information through sub-model analysis, can lead to a significant reduction in the parameter marginal posterior variance. We first consider virtual patient conditions, with clinical targets generated through model solutions, and second application to a cohort of four single-ventricle patients with Norwood physiology. Copyright © 2016 John Wiley & Sons, Ltd.

Decline of Systolic and Diastolic 2D Strain Rate During Follow-Up of HLHS Patients After Fontan Palliation

Accurate assessment of ventricular function is particularly important in children with hypoplastic left heart syndrome (HLHS) after completion of the total cavopulmonary connection (TCPC). For this purpose, two-dimensional speckle tracking (2DST) is a promising technique as it does not depend on the angle of insonation or the geometry of the ventricle. The objective of this study was to assess changes in systolic and diastolic right ventricular (RV) function within a 5-year follow-up period of HLHS patients after TCPC using conventional and 2DST echocardiography. RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), E/A, E/e' and 2DST parameters [global longitudinal peak systolic strain (GS) and strain rate (GSRs), global strain rate in early (GSRe) and late (GSRa) diastole] of 40 HLHS patients were compared at 1.6 and at 5.1 years after TCPC. RVFAC, E/A, E/e' and GS did not change, whereas TAPSE (13.7 ± 3.2 vs. 10.5 ± 2.4 mm/m(2), p < 0.001), GSRs (-1.56 ± 0.28 vs. -1.35 ± 0.31 1/s, p < 0.001), GSRe (2.22 ± 0.49 vs. 1.96 ± 0.44 1/s, p = 0.004) and GSRa (1.19 ± 0.39 vs. 0.92 ± 0.39 1/s, p < 0.001) decreased significantly. Systolic and diastolic RV function parameters of HLHS patients decreased from 1.6 to 5.1 years after TCPC in our patients. Changes in global strain rate parameters may be signaling early RV dysfunction that is not detectable by traditional echocardiography. Further study is needed to verify this and to determine whether these changes are clinically relevant.

Evaluation of single right atrial volume and function with magnetic resonance imaging in children with hypoplastic left heart

BACKGROUND

Standardized methods to evaluate atrial properties in single ventricles are lacking.

OBJECTIVE

To determine the feasibility of quantifying right atrial volumes and function in hypoplastic left heart using MRI.

MATERIALS AND METHODS

We studied 15 infants with hypoplastic left heart prior to Glenn surgery (mean age 4.2 months [standard deviation 0.3]) who underwent cardiac MRI with evaluation of atrial volumes and emptying fraction using monoplane two-chamber, monoplane four-chamber, and biplane methods, all of which were compared to the atrial short-axial oblique stack method. We compared atrial end-diastolic volume, end-systolic volume and emptying fraction among these methods. We analyzed reproducibility of the methods using Bland‒Altman plots.

RESULTS

Both four-chamber and biplane methods showed high correlations for atrial end-diastolic volume (r = 0.7 and r = 0.8, respectively; P < 0.01) and end-systolic volume (r = 0.8 and r = 0.9, respectively; P < 0.01) with small mean differences (-0.2 ± 2.9 standard deviation [SD] ml and -0.8 ± 1.6 ml, respectively, for atrial end-diastolic volume and -0.8 ± 1.5 ml and -0.9 ± 0.9 ml, respectively, for atrial end-systolic volume). The short-axial oblique method was the most reproducible, followed by the four-chamber method.

CONCLUSION

MRI assessment of atrial volume and function is feasible in hypoplastic left heart and might provide further insight into single-ventricle mechanics.

Assessment of Speckle-Tracking Echocardiography-Derived Global Deformation Parameters During Supine Exercise in Children

Exercise echocardiography is an underutilized tool in pediatrics with current applications including detecting segmental wall abnormalities, assessing the utility of global ventricular function, and measuring pulmonary hemodynamics. No prior study has applied speckle-tracking echocardiography (STE) during exercise echocardiography in children. The aim of this study was to determine the feasibility of measuring speckle-tracking-derived peak systolic velocities, global longitudinal and circumferential strain, and global strain rates at various phases of exercise. Ninety-seven healthy children underwent cardiopulmonary exercise testing using supine cycle ergometry. The exercise stress test consisted of baseline pulmonary function testing, monitoring of blood pressure and heart rate responses, electrocardiographic recordings, and oxygen saturations while subjects pedaled against a ramp protocol based on body weight. Echocardiographic measurements and specifically speckle-tracking analysis were performed during exercise at baseline, at a heart rate of 160 beats per minute and at 10 min after exercise. Peak systolic velocity, peak systolic strain, and peak systolic strain rate at these three phases were compared in the subjects in which all measurements were accurately obtained. We were able to complete peak velocity, strain, and strain rate measurements in all three exercise phases for 36 out of the 97 subjects tested. There was no significant difference between the feasibility of measuring circumferential versus longitudinal strain (p = 0.25, B-corrected = 0.75). In the 36 subjects studied, the magnitude of circumferential strain values decreased from -18.3 ± 4.8 to -13.7 ± 4.0 % from baseline to HR 160 (p < 0.0001, B-corrected < 0.0001), before returning to -19.6 ± 4.4 % at recovery (p = 0.19 when compared to baseline). Longitudinal strain did not vary significantly from baseline to HR 160 (from -17.7 ± 4.4 to -16.6 ± 4.4 %, p = 0.16); likewise the average recovery strain was no different from those values (-18.4 ± 3.6 %; p = 0.34). Peak circumferential and longitudinal strain rates increased from baseline to HR 160, but neither decreased to baseline levels after 10 min of recovery, which correlated with heart rate variations with exercise. We studied the effects of frame rate on deformation measurements and we observed no difference between measurements taken at lower (<60 frames per second, fps) and higher (≥60 fps) frame rates. This study shows that it is technically difficult to retrospectively measure peak velocities, strain, and strain rate in exercising pediatric subjects with STE. The majority of subjects that were excluded from the study had inadequate echocardiographic images when tachycardic from increased respiratory effort and body movements near peak exercise. Improvements in technique and higher image frame rates could make application of STE to pediatric cardiopulmonary testing more successful in the future.

Influence of exercise mode on pregnancy outcomes: ENHANCED by Mom project

Background

The extent of the benefits of exercise training during pregnancy on maternal, fetal, and neonatal health outcomes has not been sufficiently addressed. While aerobic exercise training has been determined as safe and efficacious throughout pregnancy, the effects of other training modes on fetal health and development as well as any continued benefits for the neonate, especially with regards to cardiovascular development and function, is largely unknown. In the ENHANCED by Mom study we aim to determine the effects of different modes of exercise training (aerobic, circuit, and resistance) throughout pregnancy on childhood health by controlling individual exercise programs and assessing the effects of each on fetal and neonatal health adaptations.

Methods/Design

ENHANCED by mom is a cross sectional comparison study utilizing 3 intervention groups in comparison to a control group. Participants will complete three 5 min warmup + 45 min sessions weekly from 16 weeks to 36 weeks gestation of aerobic, resistance, or circuit training, in comparison to non-exercising controls. Maternal physical measurements will occur every 4 weeks throughout the intervention period. Fetal morphometric and heart measurements will occur at 34 weeks gestation. Neonatal measurements will be acquired at birth and at 1 month, 6 months, and 12 months.

Discussion

A better understanding on the effects of exercise training during pregnancy on fetal and neonatal health could have a profound impact on the prevention and development of chronic diseases such as obesity, hypertension, and diabetes.

Ventricular and atrial mechanics and their interaction in patients with congenital scoliosis without clinical heart failure

OBJECTIVES

This study sought to evaluate left ventricular, right ventricular, and left atrial mechanics and their interactions in patients with congenital scoliosis without clinical heart failure.

METHODS

A total of 23 patients with a median age of 14 years and a median Cobb's angle of 61° were studied. Ventricular and atrial myocardial deformation was measured using speckle tracking echocardiography. The results of the patients were compared with 22 controls.

RESULTS

Compared with controls, the patients had a significantly greater annular a velocity (p=0.04) and lower e/a ratio (p=0.03); the left ventricular deformation significantly decreased in radial global (p=0.04) and segmental systolic strain and early diastolic strain rate (p=0.03); the left atrial deformation showed a significantly lower positive strain (p=0.02), greater negative strain (p=0.01), and active contractile strain rate (p=0.01). For the patients, the Cobb's angle was negatively correlated with the left ventricular global radial systolic strain (r=-0.65, p=0.001), left atrial positive strain (r=-0.68, p<0.001), and the left atrial negative strain was positively correlated with the left ventricular circumferential late diastolic strain rate (r=0.46, p=0.01). The left atrial conduit strain rate was positively correlated with the left ventricular circumferential early diastolic strain rate (r=0.42, p=0.03). The left atrial active contractile strain rate was positively correlated with the left ventricular longitudinal late diastolic strain rate (r=-0.4, p=0.03).

CONCLUSIONS

Impaired left ventricular and altered left atrial mechanics occur relatively early in patients with congenital scoliosis, and are correlated with the severity of their scoliosis. Our findings provide evidence of preclinical heart dysfunction in patients with this disorder.

Predictors of mortality in pediatric patients on venoarterial extracorporeal membrane oxygenation

OBJECTIVES

Currently, there are no established echocardiographic or hemodynamic predictors of mortality after weaning venoarterial extracorporeal membrane oxygenation in children. We wished to determine which measurements predict mortality.

DESIGN

Over 3 years, we prospectively assessed six echo and six hemodynamic variables at 3-5 circuit rates while weaning extracorporeal membrane oxygenation flow. Hemodynamic measurements were heart rate, inotropic score, arteriovenous oxygen difference, pulse pressure, oxygenation index, and lactate. Echo variables included shortening/ejection fraction, outflow tract Doppler-derived stroke distance (velocity-time integral), degree of atrioventricular valve regurgitation, longitudinal strain (global longitudinal strain), and circumferential strain (global circumferential strain).

SETTING

Cardiovascular ICU at Lucille Packard Children's Hospital Stanford, CA.

SUBJECTS

Patients were stratified into those who died or required heart transplant (Gr1) and those who did not (Gr2). For each patient, we compared the change for each variable between full versus minimum extracorporeal membrane oxygenation flow for each group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We enrolled 21 patients ranging in age from 0.02 to 15 years. Five had dilated cardiomyopathy, and 16 had structural heart disease with severe ventricular dysfunction. Thirteen of 21 patients (62%) comprised Gr1, including two patients with heart transplants. Eight patients constituted Gr2. Gr1 patients had a significantly greater increase in oxygenation index (35% mean increase; p < 0.01) off extracorporeal membrane oxygenation compared to full flow, but no change in velocity-time integral or arteriovenous oxygen difference. In Gr2, velocity-time integral increased (31% mean increase; p < 0.01), with no change in arteriovenous oxygen difference or oxygenation index. Pulse pressure increased modestly with flow reduction only in Gr1 (p < 0.01).

CONCLUSION

Failure to augment velocity-time integral or an increase in oxygenation index during the extracorporeal membrane oxygenation weaning is associated with poor outcomes in children. We propose that these measurements should be performed during extracorporeal membrane oxygenation wean, as they may discriminate who will require alternative methods of circulatory support for survival.

Atrial and ventricular mechanics in patients after Fontan-type procedures: atriopulmonary connection versus extracardiac conduit

BACKGROUND

Differences in systemic venous flow dynamics and energy losses exist in various Fontan-type procedures, which may affect atrial and ventricular filling. The aim of this study was to test the hypothesis that atrial and ventricular mechanics differ between two types of Fontan procedures, atriopulmonary connection (APC) and extracardiac conduit, which have distinctly different systemic venous hemodynamics.

METHODS

This was a cross-sectional, case-control study of 28 Fontan patients (13 with APC, 15 with extracardiac conduit) aged 19.8 ± 6.5 years and 26 healthy controls. Atrial and systemic ventricular myocardial deformation was determined using speckle-tracking echocardiography, while ventricular volumes and systolic dyssynchrony index were assessed using three-dimensional echocardiography.

RESULTS

Compared with controls, patients had significantly lower values of global ventricular longitudinal, circumferential, and radial systolic strain in all three directions, reduced systolic and early diastolic strain rates (SRs) in more than one dimension, lower ejection fractions, and worse ventricular dyssynchrony. For atrial deformation, patients had lower global and positive strain and conduit and reservoir SRs and delayed electromechanical coupling. Among patients, those with APC had significantly lower ventricular longitudinal strain and early diastolic SRs, worse ventricular dyssynchrony, and reduced atrial positive and negative strain and conduit and active contractile SRs. Atrial global strain (r = 0.60, P = .001) and conduit SR (r = 0.49, P = .008) correlated positively with systemic ventricular early diastolic SR.

CONCLUSIONS

Atrial and ventricular mechanics are impaired in patients after Fontan-type operation, which is worse with APC than extracardiac conduit.