Single Right Ventricles Have Impaired Systolic and Diastolic Function Compared to Those of Left Ventricular Morphology

The impact of dominant ventricle morphology and additional ventricular chamber size on clinical outcomes in patients with Fontan circulation

OBJECTIVES

The functional roles of ventricular dominance and additional ventricular chamber after Fontan operation are still uncertain. We aim to assess and correlate such anatomical features to late clinical outcomes.

METHODS

Fontan patients undergoing cardiac MRI and cardiopulmonary exercise test between January 2020 and December 2022 were retrospectively reviewed. Clinical, cardiac MRI, and cardiopulmonary exercise test data from the last follow-up were analysed.

RESULTS

Fifty patients were analysed: left dominance was present in 29 patients (58%, median age 20 years, interquartile range:16-26). At a median follow-up after the Fontan operation was 16 years (interquartile range: 4-42), NYHA classes III and IV was present in 3 patients (6%), 4 (8%) underwent Fontan conversion, 2 (4%) were listed for heart transplantation, and 2 (4%) died. Statistical analysis showed that the additional ventricular chamber was larger (>20 mL/m2) in patients with a right dominant ventricle (p = 0.01), and right dominance was associated with a higher incidence of post-operative low-cardiac output syndrome (p = 0.043). Left ventricular dominance was associated with a better ejection fraction (p = 0.04), less extent of late gadolinium enhancement (p = 0.022), higher metabolic equivalents (p = 0.01), and higher peak oxygen consumption (p = 0.033). A larger additional ventricular chamber was associated with a higher need for post-operative extracorporeal membrane oxygenation support (p = 0.007), but it did not influence functional parameters on cardiac MRI or cardiopulmonary exercise test.

CONCLUSIONS

In Fontan patients, left ventricular dominance correlated to better functional outcomes. Conversely, a larger additional ventricular chamber is more frequent in right ventricular dominance and can negatively affect the early post-Fontan course.

Echocardiographic Strain to Predict Need for Transplant or Mortality in Fontan Patients with Hypoplastic Left Heart Syndrome

Despite recent advances, hypoplastic left heart syndrome (HLHS) patients subsequent to the Fontan still have significant morbidity and mortality. Some require heart transplant due to systemic ventricular dysfunction. Limited data exist on timing for transplant referral. This study aims to correlate systemic ventricular strain by echocardiography to transplant-free survival. HLHS patients who had Fontan palliation at our institution were included. Patients were divided into: 1) Required transplant or experienced mortality (composite end point); 2) Did not require transplant or survived. For those who experienced the composite endpoint, the last echocardiogram prior to the composite outcome was used, while for those who did not experience the composite endpoint the last echocardiogram obtained was used. Several qualitative and quantitative parameters were analyzed with focus on strain parameters. Ninety-five patients with HLHS Fontan palliation were identified. Sixty-six had adequate images and eight (12%) experienced transplant or mortality. These patients had greater myocardial performance index by flow Doppler (0.72 versus 0.53, p = 0.01), higher systolic/diastolic duration ratio (1.51 versus 1.13, p = 0.02), lower fractional area change (17.65 versus 33.99, p < 0.01), lower global longitudinal strain (GLS) (-8.63 versus - 17.99, p < 0.01), lower global longitudinal strain rate (GLSR) (- 0.51 versus - 0.93, p < 0.01), lower global circumferential strain (GCS) (-6.68 versus -18.25, p < 0.01), and lower (GCSR) global circumferential strain rate (-0.45 versus -1.01, p < 0.01). ROC analysis demonstrated predictive value for GLS - 7.6 (71% sensitive, 97% specific, AUC 81%), GLSR -0.58 (71% sensitive, 88% specific, AUC 82%), GCS - 10.0 (86% sensitive, 91% specific, AUC 82%), and GCSR -0.85 (100% sensitive, 71% specific, AUC 90%). GLS and GCS can help predict transplant-free survival in patients with hypoplastic left heart syndrome having undergone Fontan palliation. Higher strain values (closer to zero) may be a helpful tool in determining when transplant evaluation is warranted in these patients.

Echocardiographic strain imaging in the pediatric heart: clinical value and utility in decision making

PURPOSE OF REVIEW

Speckle tracking echocardiography (STE)-derived measures of myocardial mechanics, referred to herewithin as strain measurements, directly assess myocardial contractility and provide a nuanced assessment of ventricular function. This review provides an overview of strain measurements and their current clinical value and utility in decision making in pediatric cardiology.

RECENT FINDINGS

Strain measurements are advancing understanding of how cardiac dysfunction occurs in children with acquired and congenital heart disease (CHD). Global strain measurements can detect early changes in cardiac function and are reliable methods of serially monitoring systolic function in children. Global strain measurements are increasingly reported in echocardiographic assessment of ventricular function alongside ejection fraction. Research is increasingly focused on how strain measurements can help improve clinical management, risk stratification, and prognostic insight. Although more research is needed, preliminary studies provide hope that there will be clinical benefit for strain in pediatric cardiology management.

SUMMARY

Strain measurements provide a more detailed assessment of ventricular function than conventional measures of echocardiographic functional assessment. Strain measurements are increasingly being used to advance understanding of normal and abnormal myocardial contractility, to increase sensitivity to detect early cardiac dysfunction, and to improve prognostic management in children with acquired and CHD.

The Evolution of Longitudinal Strain Across Various Univentricular Morphologies Prior to Superior Cavopulmonary Anastomosis

BACKGROUND

Infants with single-ventricle physiology have increased morbidity, mortality, and ventricular dysfunction in the pre-superior cavopulmonary anastomosis (pre-SCPA) period. Echocardiography-derived longitudinal strain (LS) is emerging as a reliable marker of single-ventricle performance. We aim to assess evolution of LS during the pre-SCPA period across univentricular morphologies and explore associations of LS with modifiable and nonmodifiable factors.

METHODS

Ninety-four term infants (36 females) with univentricular physiology who were discharged home prior to stage 2 palliation were serially analyzed for LS (single apical view) and other echo measures at initial hospital discharge and the last pre-SCPA encounter. Ventricular myocardium was tracked for strain along the septum and respective lateral wall for single right ventricular (RV) and left ventricular (LV) groups, and along both right and left lateral walls in functionally univentricular hearts with biventricular (BiV) morphology. Clinical data were obtained from the medical record.

RESULTS

Longitudinal strain improved in the total cohort during the pre-SCPA period (16.48% ± 3.31% to 17.57% ± 3.81%, P = .003). Longitudinal strain improved between encounters in the single LV (P = .04) and BiV groups (P = .02). However, LS failed to improve in the RV group (P = .7) with lower LS at both visits compared with the other groups. The RV group, mostly composed of hypoplastic left heart syndrome patients-87% of cases-had a higher incidence of arrhythmias (57%) and unplanned reinterventions (60%), most of which were arch reinterventions. A subanalysis based on arch reintervention showed that LS improves between encounters in the single LV group needing arch reintervention (P = .05) compared with the single RV group needing arch reintervention (P = .89). Lower LS was independently associated with unplanned reinterventions at both encounters (P = .008 and .02).

CONCLUSIONS

Single-ventricle LS evolves differently across ventricular morphologies during the pre-SCPA period and is related to the need for unplanned cardiac reinterventions. Lower LS is noted in the single RV group, who mostly have hypoplastic left heart syndrome.

Diastolic myocardial mechanics and their relation to ventricular filling pressures and postoperative course in functionally single ventricles

Diastolic dysfunction affects clinical outcomes in patients with a functionally single ventricle (FSV). The objective of this work is to study the association of ventricular mechanics and interventricular dependence on diastolic parameters and early post-Fontan outcomes. Sixty-one patients with FSV underwent echocardiography, cardiac catheterization, and magnetic resonance imaging on the same day before or after the Fontan procedure. Echocardiographic diastolic parameters, ventricular mass, and incoordinate wall motion, defined by the number of dyskinetic segments or by the lateral wall delay, were determined and studied for relationships with invasively measured hemodynamics and early postoperative Fontan course. In subjects with a sizable secondary ventricle, incoordinate motion was additionally analyzed at the left- and right-sided ventricular free walls. Resting ventricular end-diastolic pressure (VEDP) was ≤10 mmHg in most subjects. Individual echocardiographic parameters of the diastolic flow and tissue velocities did not correlate with VEDP, other hemodynamics, or post-Fontan clinical course. Incoordinate wall motion in the dominant and in the sizeable secondary ventricle, defined by the lateral wall delay or by the number of dyskinetic segments, was the only echo parameter that correlated, albeit weakly, with VEDP (r = 0.247, P = 0.040), oxygen saturation (r = -0.417, P = 0.001), pulmonary vascular resistance and flow (Qp) (r = -0.303, P = 0.011), Fontan fenestration flow (r = 0.512, P = 0.009), and duration of endotracheal intubation (r = 0.292, P = 0.022). When the nondominant (secondary) ventricle was accounted for in the analysis of incoordinate wall motion, these associations strengthened. The degree of incoordinate ventricular wall motion in diastole was associated with VEDP and postoperative Fontan course in FSV. Analysis of incoordinate wall motion of the dominant and sizeable secondary ventricle may be warranted and should be included in the assessment of the FSV after the Fontan procedure.NEW & NOTEWORTHY Diastolic dysfunction affects outcomes in patients with functionally single ventricles (FSVs) but is difficult to assess. We found that incoordinate wall motion was the only echo parameter that correlated with FSV end-diastolic pressure, oxygen saturation, pulmonary vascular resistance and flow, and duration of endotracheal intubation. Analysis of incoordinate wall motion in the nondominant (secondary) ventricle strengthened these associations. Analyzing incoordinate wall motion should be included in the assessment of the FSV after the Fontan procedure.

Role of cardiac MRI in the prediction of pre-Fontan end-diastolic ventricular pressure

BACKGROUND

Growing evidence has emphasised the importance of ventricular performance in functionally single-ventricle patients, particularly concerning diastolic function. Cardiac MRI has been proposed as non-invasive alternative to pre-Fontan cardiac catheterisation in selected patients.

AIM OF THE STUDY

To identify clinical and cardiac magnetic resonance predictors of high pre-Fontan end-diastolic ventricular pressure.

METHOD

In a retrospective single-centre study, 38 patients with functionally univentricular heart candidate for Fontan intervention, who underwent pre-Fontan cardiac catheterisation, beside a comprehensive cardiac MRI, echocardiographic, and clinical assessment were included. Medical and surgical history, cardiac magnetic resonance, cardiac catheterisation, echocardiographic, and clinical data were recorded. We investigated the association between non-invasive parameters and cardiac catheterisation pre-Fontan risk factors, in particular with end-diastolic ventricular pressure. Moreover, the impact of conventional invasive pre-Fontan risk factor on post-operative outcome as also assessed.

RESULTS

Post-operative complications were associated with higher end-diastolic ventricular pressure and Mayo Clinic indexes (p < 0.01 and p = 0.05, respectively). At receiver operating characteristic curve analysis end-diastolic ventricular pressure ≥ 10.5 mmHg predicted post-operative complications with a sensitivity of 75% and specificity of 88% (AUC: 0.795, 95% CI 0.576;1.000, p < 0.05). At multivariate analysis, both systemic right ventricle (OR: 23.312, 95% CI: 2.704-200.979, p < 0.01) and superior caval vein indexed flow (OR: 0.996, 95% CI: 0.993-0.999, p < 0.05) influenced end-diastolic ventricular pressure ≥ 10.5 mmHg.

CONCLUSIONS

A reduced superior caval vein flow, evaluated at cardiac magnetic resonance, is associated with higher end-diastolic ventricular pressure a predictor of early adverse outcome in post-Fontan patients.

Impact of Udenafil on Echocardiographic Indices of Single Ventricle Size and Function in FUEL Study Participants

BACKGROUND

The FUEL trial (Fontan Udenafil Exercise Longitudinal) demonstrated statistical improvements in exercise capacity following 6 months of treatment with udenafil (87.5 mg po BID). The effect of udenafil on echocardiographic measures of single ventricle function in this cohort has not been studied.

METHODS

The 400 enrolled participants were randomized 1:1 to udenafil or placebo. Protocol echocardiograms were obtained at baseline and 26 weeks after initiation of udenafil/placebo. Linear regression compared change from baseline indices of single ventricle systolic, diastolic and global function, atrioventricular valve regurgitation, and mean Fontan fenestration gradient in the udenafil cohort versus placebo, controlling for ventricular morphology (left ventricle versus right ventricle/other) and baseline value.

RESULTS

The udenafil participants (n=191) had significantly improved between baseline and 26 weeks visits compared to placebo participants (n=195) in myocardial performance index (P=0.03, adjusted mean difference [SE] of changes between groups -0.03[0.01]), atrioventricular valve inflow peak E (P=0.009, 3.95 [1.50]), and A velocities (P=0.034, 3.46 [1.62]), and annular Doppler tissue imaging-derived peak e' velocity (P=0.008, 0.60[0.23]). There were no significant differences in change in single ventricle size, systolic function, atrioventricular valve regurgitation severity, or mean fenestration gradient. Participants with a dominant left ventricle had significantly more favorable baseline values of indices of single ventricle size and function (lower volumes and areas, E/e' ratio, systolic:diastolic time and atrioventricular valve regurgitation, and higher annular s' and e' velocity).

CONCLUSIONS

FUEL participants who received udenafil demonstrated a statistically significant improvement in some global and diastolic echo indices. Although small, the changes in diastolic function suggest improvement in pulmonary venous return and/or augmented ventricular compliance, which may help explain improved exercise performance in that cohort.

REGISTRATION

URL: https://clinicaltrials.gov; Unique Identifier: NCT02741115.

Autologous Umbilical Cord Blood-Derived Mononuclear Cell Therapy Promotes Cardiac Proliferation and Adaptation in a Porcine Model of Right Ventricle Pressure Overload

Congenital heart diseases, including single ventricle circulations, are clinically challenging due to chronic pressure overload and the inability of the myocardium to compensate for lifelong physiological demands. To determine the clinical relevance of autologous umbilical cord blood-derived mononuclear cells (UCB-MNCs) as a therapy to augment cardiac adaptation following surgical management of congenital heart disease, a validated model system of right ventricular pressure overload due to pulmonary artery banding (PAB) in juvenile pigs has been employed. PAB in a juvenile porcine model and intramyocardial delivery of UCB-MNCs was evaluated in three distinct 12-week studies utilizing serial cardiac imaging and end-of-study pathology evaluations. PAB reproducibly induced pressure overload leading to chronic right ventricular remodeling including significant myocardial fibrosis and elevation of heart failure biomarkers. High-dose UCB-MNCs (3 million/kg) delivered into the right ventricular myocardium did not cause any detectable safety issues in the context of arrhythmias or abnormal cardiac physiology. In addition, this high-dose treatment compared with placebo controls demonstrated that UCB-MNCs promoted a significant increase in Ki-67-positive cardiomyocytes coupled with an increase in the number of CD31+ endothelium. Furthermore, the incorporation of BrdU-labeled cells within the myocardium confirmed the biological potency of the high-dose UCB-MNC treatment. Finally, the cell-based treatment augmented the physiological adaptation compared with controls with a trend toward increased right ventricular mass within the 12 weeks of the follow-up period. Despite these adaptations, functional changes as measured by echocardiography and magnetic resonance imaging did not demonstrate differences between cohorts in this surgical model system. Therefore, this randomized, double-blinded, placebo-controlled pre-clinical trial establishes the safety of UCB-MNCs delivered via intramyocardial injections in a dysfunctional right ventricle and validates the induction of cardiac proliferation and angiogenesis as transient paracrine mechanisms that may be important to optimize long-term outcomes for surgically repaired congenital heart diseases.

Comparison of Myocardial Deformation by Speckle-Tracking Echocardiography and Cardiac Magnetic Resonance in Patients with Fontan Circulation: Diagnostic Algorithm

Background:

While the short- and median-term survival has improved considerably in patients with Fontan circulation, cardiac function and exercise capacity are still reduced and may deteriorate over time. Cardiac magnetic resonance (CMR) is the gold standard for the assessment of ventricular volume and function. Speckle-tracking echocardiography (STE) is a myocardial deformation technique to assess ventricular function, with promising results. The aim of our study is to validate STE and conventional echocardiography parameters and to compare them with CMR. Furthermore, we aimed to design a diagnostic algorithm applying some parameters in series for early detection of myocardial dysfunction.

Materials and Methods:

We performed a cross-sectional single-center study in 64 patients with Fontan circulation. Longitudinal and circumferential strain, strain rates, and conventional echocardiographic measurements were registered. Ventricular volumes and ejection fraction (EF) were obtained by CMR.

Results:

Seven patients presented ventricular dysfunction (EF <45% by CMR), without showing a significant correlation between STE parameters or conventional measures by echocardiography and CMR. After the application of the diagnostic algorithm with the optimal cutoff points (global longitudinal strain – 24.5%, global circumferential strain – 20%, and annular plane systolic excursion – 16.5 mm), we got a sensitivity rate and a negative predictive value of 100%. In 19 patients (40.1%), the absence of ventricular dysfunction was demonstrated without no false-negative cases.

Conclusions:

STE should be considered a complementary diagnostic tool in Fontan patients. These suggested parameters applied in series are a useful tool for identifying early ventricular dysfunction and for diagnostic tests improvement with a fewer CMRs in the follow-up of these patients.

Identification of patient variables that are associated with ventricular end-diastolic pressure before the bidirectional Glenn operation

INTRODUCTION

Systemic ventricular end-diastolic pressure is important in patients with single ventricle heart disease. Predictors of an elevated systemic ventricular end-diastolic pressure prior to bidirectional Glenn operation have been incompletely identified.

METHODS

All patients who underwent bidirectional Glenn operation operation at our centre between January 2007 and March 2017 were retrospectively identified and patient variables were extracted. For patients who had undergone Fontan operation at the time of this study, post-Fontan patient variables were also extracted.

RESULTS

One-hundred patients were included with a median age at pre-bidirectional Glenn operation catheterisation of 4.5 months. In total, 71 (71%) patients had a systemic right ventricle. At the pre-bidirectional Glenn operation catheterisation, the mean systemic ventricular end-diastolic pressure was higher amongst those with systemic right ventricle compared to left ventricle (9.1 mmHg ± 2.1 versus 7.7 ± 2.7 mmHg, p < 0.01). On univariate analysis, pre-bidirectional Glenn operation systemic ventricular end-diastolic pressure was positively associated with the presence of a systemic right ventricle (p < 0.01), history of recoarctation (p = 0.03), history of Norwood operation (p = 0.04), and ventricular systolic pressure (p < 0.01). On multivariate analysis, systemic ventricular end-diastolic pressure was positively associated with the presence of a systemic right ventricle (p < 0.01) and ventricular systolic pressure (p < 0.01). Amongst those who had undergone Fontan operation at the time of study (n = 49), those with a higher pre-bidirectional Glenn operation systemic ventricular end-diastolic pressure were more likely to have experienced death, transplantation, or listed for transplantation (p = 0.02) and more likely to have had heart failure symptoms (p = 0.04) at a mean time from Fontan of 5.2 years ± 1.3.

CONCLUSIONS

In patients undergoing bidirectional Glenn operation operation, the volume-loaded, pre-bidirectional Glenn operation state may expose diastolic dysfunction that has prognostic value.

Restriction of Atrial Septal Defect Leads to Growth of Hypoplastic Ventricle in Patients with Borderline Right or Left Heart

Patients with borderline hypoplastic right or left ventricle and VSD may be candidates for either single ventricle palliation or staged ventricular recruitment (SVR) followed by eventual biventricular conversion. Components of SVR include restriction of atrial septal defects (ASD) without ventricular septal defects (VSD) closure and addition of accessory pulmonary blood flow. This study evaluated the impact of ASD restriction on ventricular growth and function. We retrospectively reviewed patients with borderline ventricular hypoplasia and VSD who underwent a staged ventricular recruitment (SVR) procedure from 2012 to June 2019. Pre- and post-recruitment MRI and echocardiogram data were compared and analyzed. We excluded cases in which we intentionally restricted VSD with simultaneous ASD restriction. Forty-six patients (41 with right-dominant ventricle, 25 with risk factors for Fontan procedure) underwent SVR at a median age of 15.1 months' (interquartile range (IQR), 7.2-37.2 months'). The median indexed ventricular end-diastolic volume, end-systolic volume, and stroke volume according to cardiac MRI significantly increased at median 11.0 months' (IQR:7.8~14.1 months') after recruitment. Among them, except 2 operative mortalities after SVR, 26 patients underwent bi-ventricular repair (56.5% including one and a half ventricle repair) at a median of 8.0 months' (IQR: 6.2-12.2 months') after recruitment. Fifteen patients await biventricular completion, and 3 patients underwent single ventricle palliation. Pulmonary blood flow (Qp) tended to increase after recruitment regardless of type of pulmonary blood flow modification without statistical significance. Six patients died at a median duration of 6.5 months' (IQR: 2.9-11.7) after SVR; 3 patients died after biventricular completion, 2 after recruitment, and 1 after returning to single ventricle palliation. All of them were considered poor Fontan candidates due to severe atrioventricular valve regurgitation, pulmonary hypertension, pulmonary vein stenosis, or airway stenosis. Restriction of the atrial septum leads to the growth of hypoplastic ventricle in patients with ventricular septal defects who undergo SVR regardless of the preoperative characteristics, and eventual biventricular repair can be performed in a subgroup of these patients. Future work is necessary to optimize timing of SVR and method of accessory pulmonary blood flow.

Super Glenn for staged biventricular repair: impact on left ventricular growth?

 

OBJECTIVES

The Super Glenn procedure involves targeted increased in blood flow to left sided heart structures with fenestrated atrial septation. The objective of this study was to examine the outcomes of patients who had this procedure as a part of biventricular staging and specifically evaluate the effect on dimensions of left heart structures.

METHODS

Data for patients who had this procedure between 2005 and 2019 were retrospectively identified.

RESULTS

Thirty-seven patients were identified. Most common diagnosis was hypoplastic left heart syndrome in 40% (n = 15). On echocardiography, the median mitral valve z score was -2.26. On cardiac magnetic resonance imaging, median indexed left ventricular end-diastolic volume was 31.5 ml/m2 and mitral/tricuspid inflow ratio was 0.35. The median age at Super Glenn was 2.3 years (interquartile range 1.5-3.6) while median weight was 12 kg (interquartile range 9.8-14). There were no early/hospital deaths. The median intensive care unit length of stay was 4 days, and median hospital length of stay was 10 days. Median follow-up for the entire cohort was 3 years (range 15 days to 13.2 years). There was a statistically significant increase in indexed left ventricular dimensions. There were 5 deaths (14%). Three patients (8%) underwent heart transplant. Freedom from death/transplant was 79% at 5 years. Seven patients (19%) needed a reoperation. Twenty-three patients (62%) underwent biventricular conversion after a median of 11.3 months after Super Glenn.

CONCLUSIONS

The Super Glenn procedure achieves consistent increase in left ventricular dimensions. This may be a useful strategy to help achieve a successful biventricular circulation in patients with borderline left ventricle. The superiority/non-inferiority of this approach over the conventional Fontan pathway is unclear.

Right Ventricular Remodeling in Hypoplastic Left Heart Syndrome is Minimally Impacted by Cardiopulmonary Bypass: A Comparison of Norwood vs. Hybrid

Right ventricular (RV) remodeling in hypoplastic left heart syndrome (HLHS) begins prenatally and continues through staged palliations. However, it is unclear if the most marked observed remodeling post-Norwood is secondary to cardiopulmonary bypass (CPB) exposure or if it is an adaptation intrinsic to the systemic RV. This study aims to determine the impact of CPB on RV remodeling in HLHS. Echocardiograms of HLHS survivors undergoing stage 1 Norwood (n = 26) or Hybrid (n = 20) were analyzed at pre- and post-stage 1, pre- and post-bidirectional cavo-pulmonary anastomosis (BCPA), and pre-Fontan. RV fractional area change (FAC), vector velocity imaging for longitudinal & derived circumferential deformation (global radial shortening (GRS) = peak radial displacement/end-diastolic diameter), and deformation ratio (longitudinal/ circumferential) were assessed. Both groups had similar age, clinical status and functional parameters pre-stage 1. No difference in RV size and sphericity at any stage between groups. RVFAC was normal (> 35%) throughout for both groups. Both Norwood and Hybrid patients had increased GRS (p = 0.0001) post-stage 1 and corresponding unchanged longitudinal strain, resulting in decreased deformation ratio (greater relative RV circumferential contraction), p = 0.0001. Deformation ratio remained decreased in both groups in subsequent stages. Irrespective of timing of the first CPB exposure, both Norwood and Hybrid patients underwent similar RV remodeling, with relative increase in circumferential to longitudinal contraction soon after stage 1 palliation. The observed RV remodeling in HLHS survivors were minimally impacted by CPB.

Single ventricle systolic function and cardiopulmonary exercise performance in adult patients with Fontan circulation

OBJECTIVE

We employed echocardiographic tissue characterization for the assessment of single ventricle systolic function and examined its relationship with cardiopulmonary exercise testing (CPET) performance in the Fontan circulation.

METHODS

40 consecutive adult Fontan patients (16 female, 24 male; mean age 26.3 ± 5.9) were enrolled in our prospective cross-sectional study. All patients underwent echocardiographic assessment including tissue characterization and CPET within 3 days from each other.

RESULTS

LAPSE (lateral annular plane systolic excursion) was higher in patients with a dominant left ventricle compared to a dominant right ventricle (12.3 + -2.6 vs 9.8 + -1.1 mm, p = .008) and in patients with AP (right atrium-pulmonary artery) connection than with lateral tunnel or extracardiac conduits (13.9 ± 1.7 vs 11.3 ± 2.6 and 10.9 ± 2.2 mm, p = .014 and p = .014, respectively). Maximal oxygen pulse (O₂ pulse max) was significantly higher in patients with a dominant left or common ventricle compared to patients with a dominant right ventricle (10.3 and 12.0 vs 6.6 ml/beat, p = .002 and p = .032, respectively). There was a positive correlation between O₂ pulse max and LAPSE (r = 0.442, p = .009), atrioventricular valve annulus systolic velocity (S') (r = 0.606, p < .0001), lateral wall basal segment systolic velocity (bas vel s) (r = 0.469, p = .009) and lateral wall mid segment systolic velocity (mid vel s) (r = 0.452, p = .012). In the multivariable regression model, S' (r = 0.606, p < .0001) remained predictive of O₂ pulse max.

CONCLUSIONS

LAPSE and S' are suitable parameters for the assessment of systolic function in Fontan patients. Subclinical systolic dysfunction of longitudinal fibers is associated with worse CPET performance. O₂ pulse max seems to be the best parameter reflecting Fontan patients' physical performance.

Loss of Ventricular Function After Bidirectional Cavopulmonary Connection: Who Is at Risk?

Decline of single ventricle systolic function after bidirectional cavopulmonary connection (BDCPC) is thought to be a transient phenomenon. We analyzed ventricular function after BDCPC according to ventricular morphology and correlated this evolution to long-term prognosis. A review from Mayo Clinic databases was performed. Visually estimated ejection fraction (EF) was reported from pre-BDCPC to pre-Fontan procedure. The last cardiovascular update was collected to assess long-term prognosis. A freedom from major cardiac event survival curve and a risk factor analysis were performed. 92 patients were included; 52 had left ventricle (LV) morphology and 40 had right ventricle (RV) morphology (28/40 had hypoplastic left heart syndrome (HLHS)). There were no significant differences in groups regarding BDCPC procedure or immediate post-operative outcome. EF showed a significant and relevant decrease from baseline to discharge in the HLHS group: 59 ± 4% to 49 ± 7% or - 9% (p < 0.01) vs. 58 ± 3% to 54 ± 6% or - 4% in the non-HLHS RV group (p = 0.04) and 61 ± 4% to 60 ± 4% or - 1% in the LV group (p = 0.14). Long-term recovery was the least in the HLHS group: EF prior to Fontan 54 ± 2% vs. 56 ± 6% and 60 ± 4%, respectively (p < 0.01). With a median follow-up of 8 years post-BDCPC, six patients had Fontan circulation failure, four died, and three had heart transplantation. EF less than 50% at hospital discharge after BDCPC was strongly correlated to these major cardiac events (HR 3.89; 95% Cl 1.04-14.52). Patients with HLHS are at great risk of ventricular dysfunction after BDCPC. This is not a transient phenomenon and contributes to worse prognosis.

Resource Utilization for Prenatally Diagnosed Single-Ventricle Cardiac Defects: A Philadelphia Fetus-to-Fontan Cohort Study

Background

Healthcare resource utilization is substantial for single‐ventricle cardiac defects (SVCD), with effort commencing at time of fetal diagnosis through staged surgical palliation. We sought to characterize and identify variables that influence resource utilization for SVCD from fetal diagnosis through death, completed staged palliation, or cardiac transplant.

Methods and Results

Patients with a prenatal diagnosis of SVCD at our institution from 2004 to 2011 were screened. Patients delivered with intent to treat who received cardiac care exclusively at our institution were included. Primary end points included the total days hospitalized and the numbers of echocardiograms and cardiac catheterizations. Subanalysis was performed on survivors of completed staged palliation on the basis of Norwood operation, dominant ventricular morphology, and additional risk factors. Of 202 patients born with intent to treat, 136 patients survived to 6 months after completed staged palliation. The median number of days hospitalized per patient‐year was 25.1 days, and the median numbers of echocardiograms and catheterizations per patient‐year were 7.2 and 0.7, respectively. Mortality is associated with increased resource utilization. Survivors had a cumulative length of stay of 57 days and underwent a median of 21 echocardiograms and 2 catheterizations through staged palliation. Right‐ventricle–dominant lesions requiring Norwood operation are associated with increased resource utilization among survivors of staged palliation.

Conclusions

For fetuses with SVCD, those with dominant right‐ventricular morphology requiring Norwood operation demand increased resource utilization regardless of mortality. Our findings provide insight into care for SVCD, facilitate precise prenatal counseling, and provide information about the resources utilized to successfully manage SVCD.

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.

Longitudinal Assessment of Outcome From Prenatal Diagnosis Through Fontan Operation for Over 500 Fetuses With Single Ventricle-Type Congenital Heart Disease: The Philadelphia Fetus-to-Fontan Cohort Study

Background Prenatal diagnosis of single ventricle-type congenital heart disease is associated with improved clinical courses. Prenatal counseling allows for optimal delivery preparations and opportunity for prenatal intervention. Expectant parents frequently ask what the likelihood of survival through staged palliation is and the factors that influence outcome. Our goal was specifically to quantify peri- and postnatal outcomes in this population. Methods and Results We identified all patients with a prenatal diagnosis of single ventricle-type congenital heart disease presenting between July 2004 and December 2011 at our institution. Maternal data, fetal characteristics, and data from the postnatal clinical course were collected for each patient. Kaplan-Meier curves and multivariate analysis with logistic regression were used to evaluate variables associated with decreased transplant-free survival. Five hundred two patients were identified, consisting of 381 (76%) right ventricle- and 121 left ventricle-dominant lesions. After prenatal diagnosis, 42 patients did not follow up at our center; 79 (16%) chose termination of pregnancy, and 11 had intrauterine demise with 370 (74%) surviving to birth. Twenty-two (6%) underwent palliative care at birth. Among 348 surviving to birth with intention to treat, 234 (67%) survived to at least 6 months post-Fontan palliation. Presence of fetal hydrops, right ventricle dominance, presence of extracardiac anomalies, and low birthweight were significantly associated with decreased transplant-free survival. Conclusions In patients with a prenatal diagnosis of single ventricle-type congenital heart disease and intention to treat, 67% survive transplant-free to at least 6 months beyond Fontan operation. An additional 5% survive to 4 years of age without transplant or Fontan completion. Fetuses with right ventricle-dominant lesions, extracardiac anomalies, hydrops, or low birthweights have decreased transplant-free survival.

Right Ventricular Systolic Function Parameters in Hypoplastic Left Heart Syndrome

Assessment of the systolic function of the right ventricle (RV) in patients with hypoplastic left heart syndrome (HLHS) is important. The asymmetric shape and heavy trabeculations make accurate assessment of RV systolic function challenging. Novel measures of RV function could be helpful in distinguishing reduced versus preserved function in HLHS and may also be worse in HLHS with preserved function compared to normal controls. These novel methods offer promise, but research and clinical applicability is hindered as no cut-off values for normal function have been established. We performed a retrospective comparison of functional assessments from echocardiograms of HLHS patients with preserved and reduced RV function along with a control group of normal patients. Measures of function included fractional area change (FAC), tissue motion annular displacement of the tricuspid (TMAD-TV) and pulmonary valves (TMAD-PV), myocardial performance index (MPI), tricuspid tissue Doppler S' velocity, and RV global longitudinal strain (RVGLS). Comparisons were made between three groups: normal patients, HLHS with preserved function, and HLHS with reduced function defined as FAC < 35%. FAC was chosen as the reference as it is a historical standard. 41 HLHS patients were studied. Of these patients, 20 had HLHS with reduced function, and 21 had preserved function. They were compared with 27 age-matched, normal, controls. Comparison between HLHS and normal controls: in HLHS with preserved RV systolic function, compared to normal controls, tissue Doppler S', MPI, and TMAD-TV were all abnormal (all p < 0.05). RVGLS was not statistically different (20.5 ± 3.6% for normal vs. 17.9 ± 2.6% for HLHS with preserved function). TMAD-PV was similar between groups (16.1 ± 4.6% vs. 16.7 ± 5.1%). All measures were significantly worse (all p < 0.05) in the HLHS with reduced function group compared to normal controls. Comparison between HLHS preserved vs reduced function: in HLHS with reduced function defined by FAC < 35%, all measures were significantly worse compared to HLHS with preserved function (all p < 0.05). The cut-off values that correspond to a FAC of > 35% were 14.5% for TMAD-TV and 16% for RVGLS. All measures except RVGLS and TMAD-PV estimated worse function than controls even for HLHS with preserved function. Each of the functional measures was able to identify preserved vs reduced function in HLHS with FAC as the reference standard. Cut-off values between preserved and reduced function in HLHS were estimated for TMAD-TV and RVGLS based on a relatively small cohort. These cut-off values will aid in the research design of future studies.

Reduced Right Ventricular Fractional Area Change, Strain, and Strain Rate before Bidirectional Cavopulmonary Anastomosis is Associated with Medium-Term Mortality for Children with Hypoplastic Left Heart Syndrome

BACKGROUND

Ventricular dysfunction is associated with increased morbidity and mortality in children with hypoplastic left heart syndrome. The aim of this study was to assess the diagnostic performance of conventional and speckle-tracking echocardiographic measures of right ventricular (RV) function before bidirectional cavopulmonary anastomosis palliation in predicting death or need for heart transplantation (HTx).

METHODS

RV fractional area change (RVFAC) and longitudinal and circumferential strain and strain rate (SR) were measured in 64 prospectively recruited patients with hypoplastic left heart syndrome from echocardiograms obtained before bidirectional cavopulmonary anastomosis surgery. The composite end point of death or HTx was examined. Receiver operating characteristic analysis was performed, and cutoff values optimizing sensitivity and specificity were derived.

RESULTS

At a median follow-up of 5.0 years (interquartile range, 2.8-6.4 years), 13 patients meeting the composite end point had lower longitudinal strain and SR, circumferential SR, and RVFAC compared with survivors (n = 51). The conventional cutoff of RVFAC < 35% was specific for death or HTx (86%) but had poor sensitivity (46%), with an area under the curve of 0.73. Speckle-tracking echocardiographic variables showed similar areas under the curve (range, 0.69-0.79), with negative predictive values >90%. Addition of speckle-tracking echocardiographic variables to RVFAC < 35% showed no added benefit. However, in a subpopulation of patients with RVFAC ≥ 35% (n = 44), those meeting the composite end point (n = 7) had lower longitudinal SR (median, -1.0 1/sec [interquartile range, -0.8 to -1.1 1/sec] vs -1.21/sec [interquartile range, -1.0 to -1.3 1/sec], P = .03). Interobserver reproducibility was superior for longitudinal strain and SR (intraclass correlation coefficient > 0.92) compared with RVFAC (intraclass correlation coefficient = 0.75).

CONCLUSIONS

Children with hypoplastic left heart syndrome with normal RVFAC and ventricular deformation before bidirectional cavopulmonary anastomosis have a low likelihood of death or HTx in the medium term. In the presence of reduced RVFAC, speckle-tracking echocardiography does not provide additional prognostic value. However, in patients with "normal" RVFAC, it may have a role in improving outcome prediction and warrants further investigation.

Risk Factors for an Elevated Ventricular End-Diastolic Pressure Prior to the Fontan Operation

Systemic ventricular end-diastolic pressure (SVEDP) is an important determinant of pulmonary artery pressure in those with a Fontan circulation. Predictors of an elevated SVEDP have been incompletely identified in this population. All who underwent the Fontan operation at our center between 1/2009 and 12/2013 were retrospectively identified. SVEDP at the pre-Fontan catheterization and other patient variables were extracted. We identified 61 patients. Pre-Fontan SVEDP was positively associated with systemic ventricular systolic pressure (β = 0.4, p = 0.004), aortic systolic pressure (β = 0.3, p = 0.007), aortic mean pressure (β = 0.3, p = 0.02), and decreased ventricular systolic function (p = 0.03). Compared to those with pre-Fontan SVEDP ≤ 7 mmHg, patients with SVEDP > 7 mmHg had higher average ventricular systolic pressure (85.0 ± 7.5 vs. 78.7 ± 8.3 mmHg, p = 0.003), higher average descending aorta mean pressure (62.4 ± 4.9 vs. 58.6 ± 8.1 mmHg, p = 0.03), and a higher incidence of decreased ventricular systolic function (36 vs. 15%, p = 0.07). For those with a systemic right ventricle, the SVEDP decreased significantly from the pre-Stage 2 to pre-Fontan measurements (8.7 ± 2.6 vs. 7.3 ± 2.0 mmHg, p = 0.02), but not for those with a systemic left ventricle (7.8 ± 2.0 vs. 7.2 ± 1.8 mmHg, p = 0.3). At pre-Fontan catheterization, decreased ventricular systolic function and markers of systemic afterload were positively associated with the SVEDP. SVEDP decreased significantly after Stage 2 for those with a systemic right ventricle, but not for those with a systemic left ventricle; the systemic right ventricle may be particularly vulnerable to pre-Stage 2 volume loading.

Feasibility of Computational Fluid Dynamics for Evaluating the Intraventricular Hemodynamics in Single Right Ventricle Based on Echocardiographic Images

This study introduced a combined computational fluid dynamics (CFD) and echocardiography methodology to simulate blood flow in the single right ventricle (SRV) and normal ventricles to study the intraventricular flow. Derived from echocardiographic image loops, CFD-based three-dimensional (3D) flow models of normal subject's left ventricle (LV) and right ventricle (RV) and SRV with and without heart failure at three characteristic diastolic statuses were reconstructed. The CFD derived morphological and functional measurements in normal ventricles and the SRV were validated with echocardiography. The vortex in the normal ventricles and the SRV were studied. The morphological and functional measurements derived from CFD modeling and echocardiography were comparable, and both methods demonstrated the larger volume and higher spherical index in the SRV, in particular the SRV with heart failure. All the vortices in the SRV were smaller than those in the normal control subject's LV and RV, notably with heart failure. Unlike normal LV and RV, no vortex ring was observed in the SRV. Echocardiography-based CFD demonstrated the feasibility of quantifying ventricular morphology and function; in addition, CFD can detect the abnormal flow pattern (smaller or obliterated vortices) in the SRV when compared with normal ventricles.

Longitudinal Myocardial Deformation Does Not Predict Single Ventricle Ejection Fraction Assessed by Cardiac Magnetic Resonance Imaging in Children with a Total Cavopulmonary Connection

Survival of children with single ventricle heart defects after the total cavopulmonary connection (TCPC) has improved, but impaired cardiac function remains a major cause of morbidity and mortality. Cardiac magnetic resonance imaging (cMRI) is the gold standard in assessing single ventricle volume and function, but high costs and limited availability hamper its routine use. A cheaper and more available alternative is echocardiography. Myocardial function can be studied in more detail using speckle tracking echocardiography (STE). The purpose of the study was to describe the association between myocardial deformation assessed by speckle tracking echocardiography (STE) and single ventricle function assessed by cMRI and to evaluate differences in myocardial deformation in children with single left and single right ventricular morphology. Cross-sectional, multicenter study in 77 children after TCPC was conducted. STE segmental and global longitudinal peak strain and systolic strain rate (SR) of the dominant ventricle were measured. Impaired SV function by cMRI was defined as ejection fraction (EF) < 45%. Mean age was 11.8 (range 9.7-14.3) years. Pearson R for cMRI EF versus global longitudinal strain and SR was - 0.25 (p = 0.06) and - 0.03 (p = 0.82), respectively. Global single ventricle longitudinal strain and SR was similar in patients after TCPC with single left and single right ventricular morphology (- 19.0 ± 3.1% vs 19.2 ± 3.2%, p = 0.94). STE myocardial deformation parameters do not correlate with single ventricle ejection fraction assessed by cMRI.

Systemic right ventricular morphology in the early postoperative course after extracardiac Fontan operation: is there still a need for special care?

Objectives

We aimed to compare early postoperative outcome after extracardiac (EC) Fontan operation between patients with right (RV) or left (LV) systemic ventricles.

Methods

In total, 173 consecutive patients (median age 4 years, median weight 14 kg) underwent EC Fontan between 1995 and 2013. Pre- and intraoperative data as well as detailed postoperative haemodynamic variables were compared between patients with LV [ n  = 109 (63%)] and RV [ n  = 64 (37%)].

Results

: RV patients showed significantly lower mean arterial (median 55 vs 59 mmHg, P  = 0.04), higher atrial (median 8 vs 6 mmHg, P  = 0.03) and comparable pulmonary pressure (median 14 vs 14 mmHg, P  = 0.7) as well as lower mean systemic perfusion pressure (median 39 vs 43 mmHg, P  = 0.03) on Day 0 after EC Fontan. They suffered from longer intubation time (median 18 vs 12 h, P  = 0.008), higher incidence of ascites (46% vs 28%, P  = 0.04) and need for dialysis (21% vs 4%, P  = 0.003). Prolonged inotropic support (25% vs 8%, P  = 0.02) and pharmacological treatment to reduce pulmonary vascular resistance (71% vs 53%, P  = 0.002) were more often used in RV patients and they showed more often supraventricular tachyarrhythmia (27% vs 5%, P  < 0.001) and a longer intensive care unit-stay (median 4 vs 3 days, P  = 0.03). However, early mortality, need for Fontan takedown, use of mechanical circulatory support, pleural effusions and hospital stay were not significantly different between both groups.

Conclusions

Patients with systemic RV demonstrate higher morbidity in the early postoperative course compared with patients with systemic LV anatomy and require intensified postoperative management to avoid postoperative Fontan failure.

Stem cell therapy for the systemic right ventricle

INTRODUCTION

In specific forms of congenital heart defects and pulmonary hypertension, the right ventricle (RV) is exposed to systemic levels of pressure overload. The RV is prone to failure in these patients because of its vulnerability to chronic pressure overload. As patients with a systemic RV reach adulthood, an emerging epidemic of RV failure has become evident. Medical therapies proven for LV failure are ineffective in treating RV failure. Areas covered: In this review, the pathophysiology of the failing RV under pressure overload is discussed, with specific emphasis on the pivotal roles of angiogenesis and oxidative stress. Studies investigating the ability of stem cell therapy to improve angiogenesis and mitigate oxidative stress in the setting of pressure overload are then reviewed. Finally, clinical trials utilizing stem cell therapy to prevent RV failure under pressure overload in congenital heart disease will be discussed. Expert commentary: Although considerable hurdles remain before their mainstream clinical implementation, stem cell therapy possesses revolutionary potential in the treatment of patients with failing systemic RVs who currently have very limited long-term treatment options. Rigorous clinical trials of stem cell therapy for RV failure that target well-defined mechanisms will ensure success adoption of this therapeutic strategy.

The Effect of the Superior Cavopulmonary Anastomosis on Ventricular Remodeling in Infants with Single Ventricle

BACKGROUND

Infants with single ventricular physiology have volume and pressure overload that adversely affect ventricular mechanics. The impact of superior cavopulmonary anastomosis (SCPA) on single left ventricles versus single right ventricles is not known.

METHODS

As part of the Pediatric Heart Network placebo-controlled trial of enalapril in infants with single ventricular physiology, echocardiograms were obtained before SCPA and at 14 months and analyzed in a core laboratory. Retrospective analysis of the following measurements included single ventricular end-diastolic volume (EDV), end-systolic volume (ESV), mass, mass-to-volume ratio (mass/volume), and ejection fraction. Qualitative assessment of atrioventricular valve regurgitation and assessment of diastolic function were also performed.

RESULTS

A total of 156 participants underwent echocardiography at both time points. Before SCPA, mean ESV and mass Z scores were elevated (3.4 ± 3.7 and 4.2 ± 2.9, respectively) as were mean EDV and mass/volume Z scores (2.1 ± 2.5 and 2.0 ± 2.9, respectively). EDV, ESV, and mass decreased after SCPA, but mass/volume and the degree of atrioventricular valve regurgitation did not change. Subjects with morphologic left ventricles demonstrated greater reductions in ventricular volumes and mass than those with right ventricles (mean change in Z score: left ventricular [LV] EDV, -1.9 ± 2.1; right ventricular EDV, -0.7 ± 2.5; LV ESV, -2.3 ± 2.9; right ventricular ESV, -0.9 ± 4.6; LV mass, -2.5 ± 2.8; right ventricular mass, -1.3 ± 2.6; P ≤ .03 for all). Approximately one third of patients whose diastolic function could be assessed had abnormalities at each time point.

CONCLUSIONS

Decreases in ventricular size and mass occur in patients with single ventricle after SCPA, and the effect is greater in those with LV morphology. The remodeling process resulted in commensurate changes in ventricular mass and volume such that the mass/volume did not change significantly in response to the volume-unloading surgery.

Non-invasive measurement of cardiac output using AESCULON® mini after Fontan operation

BACKGROUND

Electrical velocimetry correlates well with established methods of measuring cardiac output (CO) such as thermodilution and echocardiography. In this study, we compared the cardiac function of children with single right ventricle (SRV) and single left ventricle (SLV) on non-invasive postoperative measurement of hemodynamic parameters using AESCULON^® mini.

METHODS

Demographic, preoperative, and perioperative data were obtained from medical records. We retrospectively reviewed the AESCULON mini data of 21 patients with single ventricle who underwent Fontan operation. The patients were divided into two groups according to morphologic diagnosis: SRV (n = 9) and SLV (n = 12). The following hemodynamic parameters were analyzed: stroke volume (SV); CO; cardiac index (CI); stroke volume variation (SVV); and ventricular ejection time (VET).

RESULTS

Hemodynamic parameters were as follows (SRV vs SLV): heart rate (HR), 140.5 beats/min versus 121 beats/min; SV, 14.5 mL vs 19.9 mL; CO, 2 L/min vs 2.3 L/min; CI, 4.3 L/min/m² versus 4.4 L/min/m² ; SVV, 15.5% versus 13.9%; and VET, 167.7 s versus 197.7 s. HR and VET were statistically different between the two groups.

CONCLUSIONS

CI does not differ with laterality of the single ventricle. SRV VET, however, was significantly shorter than SLV VET in the acute postoperative period. Conversely, SRV HR was higher than SLV HR, which may mean that SRV compensates for lower VET by increasing HR.

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.

The comparative role of echocardiography and MRI for identifying critical lesions in patients with single-ventricle physiology, before bidirectional cavopulmonary connection

BACKGROUND

In the era of multi-modality imaging, this study compared contemporary, pre-operative echocardiography and cardiac MRI in predicting the need for intervention on additional lesions before surgical bidirectional cavopulmonary connection.

METHODS

A total of 72 patients undergoing bidirectional cavopulmonary connection for single-ventricle palliation between 2007 and 2012, who underwent pre-operative assessment using both echocardiography and MRI, were included. The pre-determined outcome measure was any additional surgical or catheter-based intervention within 6 months of bidirectional cavopulmonary connection. Indices assessed were as follows: indexed dimensions of right and left pulmonary arteries, coarctation of the aorta, adequacy of interatrial communication, and degree of atrioventricular valve regurgitation.

RESULTS

Median age at bidirectional cavopulmonary connection was 160 days (interquartile range 121-284). The following MRI parameters predicted intervention: Z score for right pulmonary artery (odds ratio 1.77 (95% confidence interval 1.12-2.79, p=0.014)) and left pulmonary artery dimensions (odds ratio 1.45 (1.04-2.00, p=0.027)) and left pulmonary artery report conclusion (odds ratio 1.57 (1.06-2.33)). The magnetic resonance report predicted aortic arch intervention (odds ratio 11.5 (3.5-37.7, p=0.00006)). The need for atrioventricular valve repair was associated only with magnetic resonance regurgitation fraction score (odds ratio 22.4 (1.7-295.1, p=0.018)). Echocardiography assessment was superior to MRI for predicting intervention on interatrial septum (odds ratio 27.7 (6.3-121.6, p=0.00001)).

CONCLUSION

For branch pulmonary arteries, aortic arch, and atrioventricular valve regurgitation, MRI parameters more reliably predict the need for intervention; however, echocardiography more accurately identified the adequacy of interatrial communication. Approaching bidirectional cavopulmonary connection, the diagnostic strengths of MRI and echocardiography should be acknowledged when considering intervention.

Regenerative Medicine Strategies for Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS), the most severe and common form of single ventricle congenital heart lesions, is characterized by hypoplasia of the mitral valve, left ventricle (LV), and all LV outflow structures. While advances in surgical technique and medical management have allowed survival into adulthood, HLHS patients have severe morbidities, decreased quality of life, and a shortened lifespan. The single right ventricle (RV) is especially prone to early failure because of its vulnerability to chronic pressure overload, a mode of failure distinct from ischemic cardiomyopathy encountered in acquired heart disease. As these patients enter early adulthood, an emerging epidemic of RV failure has become evident. Regenerative medicine strategies may help preserve or boost RV function in children and adults with HLHS by promoting angiogenesis and mitigating oxidative stress. Rescuing a RV in decompensated failure may also require the creation of new, functional myocardium. Although considerable hurdles remain before their clinical translation, stem cell therapy and cardiac tissue engineering possess revolutionary potential in the treatment of pediatric and adult patients with HLHS who currently have very limited long-term treatment options.

Stem cell therapies in patients with single ventricle physiology

Single ventricle physiology, especially hypoplastic left heart syndrome, is one of the most high-risk lesions in children with congenital heart disease, and the ensuing heart failure remains as a major problem related to adverse outcomes in these patients. The field of stem cell therapy for heart failure has shown striking advances during the past 10 years, and many clinical trials using stem cell technologies have been conducted in adults, which suggest that stem cell therapy is associated with long-term improvement in cardiac function. Cardiac progenitor cells have recently been discovered, and their strong regenerative ability has been demonstrated in several studies. Although no large clinical trials have been performed in the field of congenital heart disease, recent investigations indicate that stem cell therapy may hold great potential to treat children with cardiac defects.

Comparison Between Echocardiography and Cardiac Magnetic Resonance Imaging in Predicting Transplant-Free Survival After the Fontan Operation

Adverse outcomes increase in frequency as patients after Fontan operation approach adulthood. Cardiac magnetic resonance (CMR) imaging-derived parameters have been shown to predict death/transplant; however, limited data are available on the usefulness of echocardiography in risk stratification. We conducted a retrospective, single-center review of records of patients after Fontan operation with an echocardiogram and CMR within 1 year of each other. The primary end point was time to all-cause mortality or listing for transplant. Of the 127 eligible patients, there were 12 end points (9%; 10 deaths and 2 listing for transplant). Median age was 16.8 years (interquartile range 12 to 23.1) with a median follow-up of 3.8 years (interquartile range 2.6 to 5.7). Among clinical parameters, protein-losing enteropathy had the strongest association with the outcome. Among echocardiographic variables, global circumferential strain showed the strongest association (hazard ratio 1.3 per unit change, 95% confidence interval 1.1 to 1.5, p value 0.001, C-index 0.81), whereas among CMR variables indexed ventricular end-diastolic volume showed the strongest association with the outcome (hazard ratio 1.04 per 10 ml/BSA(1.3) increase in volume, 95% confidence interval 1.02 to 1.06, p value 0.001, C-index 0.82). Cox proportional hazards analysis revealed echocardiography and CMR models to each individually have a higher predictive ability than the clinical model; however, in direct comparison, neither technique was superior. In conclusion, both echocardiography-derived circumferential strain and CMR-derived ventricular end-diastolic volume index are associated with transplant-free survival in patients after Fontan operation. Echocardiography and CMR parameters have higher discriminative ability than clinical variables. Although neither imaging technique is superior in this cohort, both introduce important factors for risk stratification.

Stem cell therapy for CHD: towards translation

Stem cell therapy has the optimistic goal of regenerating the myocardium as defined by re-growth of lost or destroyed myocardium. As applied to patients with heart failure, many confuse or limit the regenerative definition to just improving myocardial function and/or decreasing myocardial scar formation, which may not be the most important clinical outcome to achieve in this promising field of molecular medicine. Many different stem cell-based therapies have been tested and have demonstrated a safe and feasible profile in adult patients with heart failure, but with varied efficacious end points reported. Although not achieved as of yet, the encompassing goal to regenerate the heart is still believed to be within reach using these cell-based therapies in adult patients with heart failure, as the first-generation therapies are now being tested in different phases of clinical trials. Similar efforts to foster the translation of stem cell therapy to children with heart failure have, however, been limited. In this review, we aim to summarise the findings from pre-clinical models and clinical experiences to date that have focussed on the evaluation of stem cell therapy in children with heart failure. Finally, we present methodological considerations pertinent to the design of a stem cell-based trial for children with heart failure, as they represent a population of patients with very different sets of issues when compared with adult patients. As has been taught by many learned clinicians, children are not small adults!

Perinatal outcome after prenatal diagnosis of single-ventricle cardiac defects

OBJECTIVES

To investigate the perinatal outcome of cases with a prenatal diagnosis of single-ventricle cardiac defects, single ventricle being defined as a dominant right ventricle (RV) or left ventricle (LV), in which biventricular circulation was not possible.

METHODS

We reviewed patients with a prenatal diagnosis of single-ventricle cardiac defects, made at one institution between 1995 and 2008. Cases diagnosed with double-inlet LV, tricuspid atresia, pulmonary atresia with intact ventricular septum and severe RV hypoplasia and those with hypoplastic left heart syndrome (HLHS) were included in the study population. Patients with HLHS were identified prenatally as being standard risk or high risk (HLHS with highly restrictive or intact atrial septum, mitral stenosis with aortic atresia and/or LV coronary artery sinusoids). Patients with an address over 200 miles from the hospital, diagnosed with heterotaxy syndrome or referred for fetal intervention, were excluded.

RESULTS

We identified 312 cases of single-ventricle cardiac defect (208 dominant RV; 104 dominant LV) that were diagnosed prenatally. Most (96%) patients with a dominant RV had HLHS. Among the total 312 cases there were 98 (31%) elective terminations of pregnancy (TOP), 12 (4%) cases of spontaneous fetal demise, 12 (4%) cases lost to prenatal follow-up and 190 (61%) live births. Among the 199 patients that underwent fetal echocardiography before 24 weeks' gestation, there were 97 (49%) cases of elective TOP. There was no difference in prenatal outcome between those with a dominant RV and those with a dominant LV (P = 0.98). Of the 190 live births, five received comfort care. With an average of 7 years' follow-up (to obtain data on the Fontan procedure), transplantation-free survival was lower in those with a dominant RV than in those with a dominant LV (standard-risk HLHS odds ratio (OR), 3.0 (P = 0.01); high-risk HLHS OR, 8.8 (P < 0.001)).

CONCLUSIONS

The prenatal outcome of cases with single-ventricle cardiac defects was similar between those with a dominant RV and those with a dominant LV, however postnatal intermediate-term survival favored those with a dominant LV. High-risk HLHS identified prenatally was associated with the lowest transplantation-free survival.

New developments in paediatric cardiac functional ultrasound imaging

Ultrasound imaging can be used to estimate the morphology as well as the motion and deformation of tissues. If the interrogated tissue is actively deforming, this deformation is directly related to its function and quantification of this deformation is normally referred as 'strain imaging'. Tissue can also be deformed by applying an internal or external force and the resulting, induced deformation is a function of the mechanical tissue characteristics. In combination with the load applied, these strain maps can be used to estimate or reconstruct the mechanical properties of tissue. This technique was named 'elastography' by Ophir et al. in 1991. Elastography can be used for atherosclerotic plaque characterisation, while the contractility of the heart or skeletal muscles can be assessed with strain imaging. Rather than using the conventional video format (DICOM) image information, radio frequency (RF)-based ultrasound methods enable estimation of the deformation at higher resolution and with higher precision than commercial methods using Doppler (tissue Doppler imaging) or video image data (2D speckle tracking methods). However, the improvement in accuracy is mainly achieved when measuring strain along the ultrasound beam direction, so it has to be considered a 1D technique. Recently, this method has been extended to multiple directions and precision further improved by using spatial compounding of data acquired at multiple beam steered angles. Using similar techniques, the blood velocity and flow can be determined. RF-based techniques are also beneficial for automated segmentation of the ventricular cavities. In this paper, new developments in different techniques of quantifying cardiac function by strain imaging, automated segmentation, and methods of performing blood flow imaging are reviewed and their application in paediatric cardiology is discussed.

Functional assessment for congenital heart disease

Significant improvement in survival of children with congenital cardiac malformations has resulted in an increasing population of adolescent and adult patients with congenital heart disease. Of the long-term cardiac problems, ventricular dysfunction remains an important issue of concern. Despite corrective or palliative repair of congenital heart lesions, the right ventricle, which may be the subpulmonary or systemic ventricular chamber, and the functional single ventricle are particularly vulnerable to functional impairment. Regular assessment of cardiac function constitutes an important aspect in the long-term follow up of patients with congenital heart disease. Echocardiography remains the most useful imaging modality for longitudinal monitoring of cardiac function. Conventional echocardiographic assessment has focused primarily on quantification of changes in ventricular size and blood flow velocities during the cardiac cycles. Advances in echocardiographic technologies including tissue Doppler imaging and speckle tracking echocardiography have enabled direct interrogation of myocardial deformation. In this review, the issues of ventricular dysfunction in congenital heart disease, conventional echocardiographic and novel myocardial deformation imaging techniques, and clinical applications of these techniques in the functional assessment of congenital heart disease are discussed.

Comparison of echocardiographic and pressure-volume loop indices of systolic function in patients with single ventricle physiology: a preliminary report

BACKGROUND

Differences in ventricular geometry and physiology of patients with single ventricle anatomy complicate the application of traditional, noninvasive measurements of systolic function. We compared noninvasive measures of ventricular systolic function in single ventricle patients with invasive measures to evaluate their validity in this population.

METHODS

A secondary analysis of patients with single ventricle physiology enrolled in the multi-institutional research project, "multi-scale modeling of single ventricle hearts," was performed. Pressure-volume loops (PVLs) were recorded using microconductance catheters. Transthoracic echocardiogram and cardiac magnetic resonance imaging were performed on the same day. PVL indices of systolic function including end-systolic elastance (Ees), maximal rate of pressure increase (dP/dTmax), and stroke work indexed to end-diastolic volume (SW/EDV) were compared with noninvasive measures, including echocardiographic myocardial performance index (MPI), rate of pressure rise (AV valve dP/dT), isovolumic acceleration, longitudinal shortening fraction (longSF), and fractional area change (FAC).

RESULTS

Fifteen patients had PVLs available for analysis. Eleven had a dominant right ventricle, three were status poststage 1 repair, five had superior cavopulmonary anastomosis, and seven had a total cavopulmonary anastomosis. FAC correlated with Ees (r = 0.69, P < .01), SW/EDV (r = 0.64, P = .01), and dP/dTmax (r = 0.59, P = .03). LongSF correlated with dP/dTmax (r = 0.61, P = .02) MPI, AV valve dP/dT, and isovolumic acceleration did not correlate with pressure-volume loop indices of systolic function.

CONCLUSIONS

Obtaining PVLs via microconductance catheters can reliably be performed in the single ventricle population and serve as a method to validate echocardiographic indices in this high-risk population. Of the echocardiographic variables, FAC showed the best correlation with PVL indices. Future studies controlling for stage of palliation should be performed to further validate echocardiographic measures of systolic function in this patient population.

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.