Tricuspid valve repair in children with hypoplastic left heart syndrome: impact of timing and mechanism on outcome

Impact of calorie intake and weight gain after Norwood procedure on the outcome of stage II palliation

BACKGROUND

This study aimed to assess the impact of caloric intake and weight-for-age-Z-score after the Norwood procedure on the outcome of bidirectional cavopulmonary shunt.

METHODS

A total of 153 neonates who underwent the Norwood procedure between 2012 and 2020 were surveyed. Postoperative daily caloric intake and weight-for-age-Z-score up to five months were calculated, and their impact on outcome after bidirectional cavopulmonary shunt was analysed.

RESULTS

Median age and weight at the Norwood procedure were 9 days and 3.2 kg, respectively. Modified Blalock-Taussig shunt was used in 95 patients and right ventricle to pulmonary artery conduit in 58. Postoperatively, total caloric intake gradually increased, whereas weight-for-age-Z-score constantly decreased. Early and inter-stage mortality before stage II correlated with low caloric intake. Older age (p = 0.023) at Norwood, lower weight (p < 0.001) at Norwood, and longer intubation (p = 0.004) were correlated with low weight-for-age-Z-score (< -3.0) at 2 months of age. Patients with weight-for-age-Z-score < -3.0 at 2 months of age had lower survival after stage II compared to those with weight-for-age-Z-score of -3.0 or more (85.3 versus 92.9% at 3 years after stage II, p = 0.017). There was no difference between inter-stage weight gain and survival after bidirectional cavopulmonary shunt between the shunt types.

CONCLUSION

Weight-for-age-Z-score decreased continuously throughout the first 5 months after the Norwood procedure. Age and weight at Norwood and intubation time were associated with weight gain. Inter-stage low weight gain (Z-score < -3) was a risk for survival after stage II.

Imaging and guiding intervention for tricuspid valve disorders using 3-dimensional transesophageal echocardiography in pediatric and congenital heart disease

In the pediatric and congenital heart disease (CHD) population, tricuspid valve (TV) disorders are complex due to the variable TV morphology, its sophisticated interaction with the right ventricle as well as associated congenital and acquired lesions. While surgery is the standard of care for TV dysfunction in this patient population, transcatheter treatment for bioprosthetic TV dysfunction has been performed successfully. Detailed and accurate anatomic assessment of the abnormal TV is essential in the preoperative/preprocedural planning. Three-dimensional transthoracic and 3D transesophageal echocardiography (3DTEE) provides added value to 2-dimensional imaging in the characterization of the TV to guide therapy and 3DTEE serves as an excellent tool for intraoperative assessment and procedural guidance of transcatheter treatment. Notwithstanding advances in imaging and therapy, the timing and indication for intervention for TV disorders in this population are not well defined. In this manuscript, we aim to review the available literature, provide our institutional experience with 3DTEE, and briefly discuss the perceived challenges and future directions in the assessment, surgical planning, and procedural guidance of (1) congenital TV malformations, (2) acquired TV dysfunction from transvenous pacing leads, or following cardiac surgeries, and (3) bioprosthetic TV dysfunction.

Tricuspid Valve Repair Can Restore the Prognosis of Patients with Hypoplastic Left Heart Syndrome and Tricuspid Valve Regurgitation: A Meta-analysis

To date, evidence supporting the efficacy of tricuspid valve (TV) repair in interrupting the progression of systemic right ventricular (RV) adverse remodeling in hypoplastic left heart syndrome (HLHS) is conflicting. We conducted a systematic review and meta-analysis of scientific literature to assess the impact of TV repair in effectively modifying the prognosis of patients with HLHS. We conducted a systematic review of PubMed, Web of Science, and Scopus databases. A random-effect meta-analysis was performed and transplant-free survival, freedom from TV regurgitation, and TV reoperation data were reconstructed using the published Kaplan-Meier curves. Nine studies were included, comprising 203 HLHS patients undergoing TV repair and 323 HLHS controls. The estimated transplant-free survival at 1, 5, and 10 years of follow-up was 75.5% [95% confidence interval (CI) = 67.6-84.3%], 63.6% [95% CI = 54.6-73.9%], and 61.9% [95% CI = 52.7-72.6%], respectively. Transplant-free survival was comparable to HLHS peers without TV regurgitation (p = 0.59). Five-year freedom from recurrence of TV regurgitation and freedom from TV reoperation was 57% [95% CI = 46.7-69.7%] and 63.6% [95% CI = 54.5-74.3%], respectively. Younger age and TV repair at the time of Norwood operation increased the risk of TV regurgitation recurrence and the need for TV reoperation. Our meta-analysis supports the efficacy of TV repair in favorably modifying the prognosis of patients with HLHS and TV regurgitation, reestablishing a medium-term transplant-free survival which is comparable to HLHS peers. However, durability of surgery and long-term fate of TV and RV performance are still unclear.

Ex Vivo Modeling of Atrioventricular Valve Mechanics in Single Ventricle Physiology

Single ventricle physiology (SVP) is used to describe any congenital heart lesion that is unable to support independent pulmonary and systemic circulations. Current treatment strategies rely on a series of palliation surgeries that culminate in the Fontan physiology, which relies on the single functioning ventricle to provide systemic circulation while passively routing venous return through the pulmonary circulation. Despite significant reductions in early mortality, the presence of atrioventricular valve (AVV) regurgitation is a key predictor of heart failure in these patients. We sought to evaluate the biomechanical changes associated with the AVV in SVP physiologies. Left and right ventricles were sutured onto patient-derived 3D-printed mounts and mounted into an ex vivo systemic heart simulator capable of reproducing Norwood, Glenn, Fontan and Late Fontan physiologies. We found that the tricuspid anterior leaflet experienced elevated maximum force, average force, and maximum yank compared to the posterior and septal leaflets. Between physiologies, maximum yank was greatest in the Norwood physiology relative to the Glenn, Fontan, and Late Fontan physiologies. These contrasting trends suggest that long- and short-term mechanics of AVV failure in single ventricle differ and that AVV interventions should account for asymmetries in force profiles between leaflets and physiologies.

Tricuspid Valve Regurgitation in Hypoplastic Left Heart Syndrome: Current Insights and Future Perspectives

Hypoplastic Left Heart Syndrome (HLHS) is a congenital heart defect that requires a three-stage surgical palliation to create a single ventricle system in the right side of the heart. Of patients undergoing this cardiac palliation series, 25% will develop tricuspid regurgitation (TR), which is associated with an increased mortality risk. Valvular regurgitation in this population has been extensively studied to understand indicators and mechanisms of comorbidity. In this article, we review the current state of research on TR in HLHS, including identified valvular anomalies and geometric properties as the main reasons for the poor prognosis. After this review, we present some suggestions for future TR-related studies to answer the central question: What are the predictors of TR onset during the three palliation stages? These studies involve (i) the use of engineering-based metrics to evaluate valve leaflet strains and predict tissue material properties, (ii) perform multivariate analyses to identify TR predictors, and (iii) develop predictive models, particularly using longitudinally tracked patient cohorts to foretell patient-specific trajectories. Regarded together, these ongoing and future efforts will result in the development of innovative tools that can aid in surgical timing decisions, in prophylactic surgical valve repair, and in the refinement of current intervention techniques.

The tricuspid valve in hypoplastic left heart syndrome: Echocardiography provides insight into anatomy and function

Tricuspid regurgitation (TR) is commonly seen in surgically palliated patients with hypoplastic left heart syndrome, and when significant, is associated with an increase in both morbidity and mortality. Tricuspid valve dysfunction appears to be the result of a combination of inherent structural malformations and the unique physiological circumstances resulting from right ventricular pressure and volume overload. Valve dysfunction evolves rapidly, and manifests early on in the surgical pathway. Whilst traditional echocardiographic imaging can identify anatomical defects and dysfunction resulting in varying degrees of regurgitation even at early stages, more sophisticated investigations such as 3D echocardiography, strain imaging and transesophageal 3DE might prove useful to better demonstrate the complex interactions between abnormal anatomy of the valve complex, ventricular function, mechanical synchrony, and TR. Recognition of specific mechanisms of TR can enhance patient-specific care by directing precise surgical interventions and by informing the best timing for intervention on the valve.

A pilot investigation of the tricuspid valve annulus in newborns with hypoplastic left heart syndrome

Objective

Hypoplastic left heart syndrome (HLHS) is a congenital disease characterized by an underdevelopment of the anatomical components inside the left heart. Approximately 30% of newborns with HLHS will develop tricuspid regurgitation, and it is currently unknown how the valve annulus mechanics and geometry are associated with regurgitation. Thus, we present an engineering mechanics-based analysis approach to quantify the mechanics and geometry of the HLHS-afflicted tricuspid valve (TV), using 4-dimensional echocardiograms.

Methods

Infants born with HLHS (n = 8) and healthy newborns (n = 4) had their TVs imaged, and the data were imported to 3D Slicer. The annular curves were defined at 5 points in the cardiac cycle. The geometry and deformation (strain) of the TV annulus were calculated to elucidate the mechanics of this critical structure and to compare them between neonates with and without HLHS.

Results

For the annular geometry, HLHS-afflicted newborns had significantly larger annular circumferences (20%-30%) and anteroposterior diameters (35%-45%) than the healthy patients. From a biomechanics' perspective, the HLHS patients had significantly smaller strains in the anterior segments (–0.1 ± 2.6%) during end-diastolic and end-isovolumetric relaxation (1.7 ± 3.0%) compared with the healthy counterparts (–13.3 ± 2.9% and 6.8 ± 0.9%, respectively).

Conclusions

The image-based analysis presented in this study may provide novel insights into the geometric and mechanistic differences in the TV annulus between the healthy and HLHS newborns. Future longitudinal studies of the biomechanics of TV annulus and other subvalvular structures may inform our understanding of the initiation and development of tricuspid regurgitation and the design of optimal repairs in this challenging population.

Surgical reintervention on the neo-aorta after the Norwood operation

OBJECTIVES

We sought to identify the prevalence of surgical reintervention on the neo-aorta after Norwood procedure and its impact on long-term outcomes.

METHODS

We reviewed the medical records of all patients who underwent Norwood procedure. The impacts of surgical neoaortic reintervention on outcomes were analysed in each stage of palliation.

RESULTS

A total of 335 patients were included in this study. Thirty patients underwent surgical reintervention on the neo-aorta after Norwood procedure. The timing of initial reintervention was before stage II in 13 patients, at stage II in 7, between stage II and stage III in 5, at stage III in 3 and after stage III in 2. A reintervention before stage II was significantly associated with mortality (HR 14.4, 95% confidence interval 6.00-34.6, P < 0.001). In patients who underwent stage II (n = 251), reintervention had no significant impact on mortality. In patients who underwent stage III (n = 188), the previous reintervention was significantly associated with higher mean pulmonary pressure (P = 0.05) and a higher rate of reduced ventricular function (P = 0.002). Greater than mild atrioventricular valve regurgitation was significantly associated with the development of a neoaortic arch stenosis after stage II (P = 0.03).

CONCLUSIONS

Surgical reinterventions on the neo-aorta were required in each inter-stage phase. A surgical neoaortic reintervention was not related to increased mortality after stage II but significantly associated with a higher rate of reduced ventricular function and elevated mean pulmonary artery pressure.

Influence of Shunt Type on Survival and Right Heart Function after the Norwood Procedure for Aortic Atresia

The study objective was to compare the results after Norwood procedure between modified Blalock-Taussig shunt (MBTS) and right ventricle-to-pulmonary artery conduit (RVPAC) according to Sano in patients with hypoplastic left heart syndrome (HLHS) and aortic atresia (AA). A total of 146 neonates with HLHS and AA who underwent the Norwood procedure at our institution between 2001 and 2020 were divided into 2 groups according to shunt type (MBTS or RVPAC). Survival after the Norwood procedure was compared between the groups. Longitudinal right ventricular and tricuspid valve function in each group were evaluated using cubic splines method. RVPAC was performed in 103 patients and MBTS in 43 according to surgeon preference. There were no differences in the 30-day mortality rates (16.5% vs 16.3%, P  = 0.973). Survival at 0.5, 1 and 3 years was 79.6%, 74.6%, and 68.9% in RVPAC and 66.8%, 64.3%, and 58.5% in MBTS (P  =  0.293). Among 23 patients undergoing tricuspid valve procedure, different mechanisms of tricuspid regurgitation were observed between the groups. Longitudinal analysis revealed greater prevalence of late right ventricular dysfunction in RVPAC patients. In 77 patients who completed Fontan procedure, the postoperative N-terminal pro B-type natriuretic peptide value was significantly higher in RVPAC vs MBTS (554 vs 276 ng/L, P  =  0.007). No survival advantage of RVPAC over MBTS was observed in neonates with HLHS and AA undergoing the Norwood procedure. Longitudinal analysis demonstrated a greater prevalence of right ventricular dysfunction and higher N-terminal pro B-type natriuretic peptide values during late follow-up in patients with RVPAC.

Preoperative risk factors influencing inter-stage mortality after the Norwood procedure

OBJECTIVES

With improvements in early survival after the stage I palliation (S1P) Norwood procedure for hypoplastic left heart syndrome (HLHS) and its variants, inter-stage death accounts for an increasing proportion of mortality. Our aim was to identify the risk factors for inter-stage mortality.

METHODS

The records of 322 neonates with HLHS or a variant who underwent the Norwood procedure at our centre between 2001 and 2019 were retrospectively analysed.

RESULTS

The diagnoses included 271 neonates with HLHS (84%) and 51 with variants (16%). Aortic atresia was observed in 138 (43%) patients, mitral atresia in 91 (28%), extracardiac anomalies in 42 (13%) and genetic disorder in 14 (4%). The median age and weight of the patients at the S1P Norwood procedure were 9 (interquartile range: 7-12) days and 3.2 (2.9-3.5) kg, respectively. The median cardiopulmonary bypass time was 137 (107-163) min. Modified Blalock-Taussig shunts were used in 159 (49%) and unvalved right ventricle-to-pulmonary artery shunts in 163 (51%) patients. The number of inter-stage deaths was as follows: between S1P and stage II palliation (S2P), 61 including 38 early (<30 days) and 23 late (>30 days) deaths, and between S2P and stage III palliation, 32 deaths. Low birth weight (<2.5 kg) (odds ratio 4.37, P = 0.020) and restrictive atrial septum (odds ratio 2.97, P = 0.013) were identified as risks for early mortality. Low birth weight [hazard ratio (HR) 0.99/g, P = 0.002] was a risk for inter-stage mortality between S1P and S2P. Extracardiac anomalies (HR 4.75, P = 0.049) and significant pre-S1P atrioventricular valve regurgitation (HR: 7.72, P = 0.016) were risks for inter-stage mortality between S2P and stage III palliation. Other anatomical variables including aortic atresia, anatomical subtypes and the diameter of the ascending aorta nor shunt type were not identified as risk factors for mortality during any inter-stage period.

CONCLUSIONS

The risk factors for inter-stage attrition after the Norwood procedure were different between each stage. Preoperative factors, including birth weight, restrictive atrial septum and extracardiac anomalies, adversely affected the inter-stage mortality.

Dynamic Systolic Changes in Tricuspid Regurgitation Vena Contracta Size and Proximal Isovelocity Surface Area in Hypoplastic Left Heart Syndrome: A Three-Dimensional Color Doppler Echocardiographic Study

BACKGROUND

The aims of this study were to investigate the dynamic changes in the vena contracta (VC) and proximal isovelocity surface area (PISA) through systole in patients with hypoplastic left heart syndrome and tricuspid regurgitation and to identify the stage of systole (early, mid, or late) in which VC and PISA radius are optimal.

METHODS

Twenty-eight patients with hypoplastic left heart syndrome were prospectively studied using continuous two-dimensional (2D) and three-dimensional (3D) echocardiography. Two-dimensional VC width, 3D VC area, and PISA radii (2D and 3D) were measured frame by frame throughout systole. The maximal 2D VC width, 3D VC area, and PISA radii in the first, middle, and last thirds of systole were compared, and correlations were explored with 3D tricuspid annular areas, right atrial volumes, and right ventricular volumes.

RESULTS

In all, 35 data sets that met inclusion criteria were analyzed. On frame-by-frame analysis, maximal 2D VC width and 3D VC area were found in the first third of systole in 17% and 20% of studies, in the second third in 34% and 31%, and in the final third in 49% and 49%. Similarly, the maximal 2D and 3D PISA radii were found in the first third of systole in 26% and 17% of studies, in the second third in 28% and 34%, and in the final third in 46% and 49%.

CONCLUSIONS

In hypoplastic left heart syndrome, detailed temporal analysis of tricuspid regurgitation-associated VC and PISA by 2D and 3D echocardiography reveals no reliable pattern predicting when in systole these parameters peak. Frame-by-frame measurement is necessary for identification of maximal VC and PISA radius on 2D and 3D color Doppler echocardiography because the severity of tricuspid regurgitation could be underestimated because of temporal variability in VC and PISA.