Characterising adequacy or inadequacy of the borderline left ventricle: what tools can we use?

Pediatric three-dimensional quantitative cardiovascular computed tomography

High-resolution, isotropic, 3-dimensional (D) data from pediatric cardiovascular computed tomography (CT) offer great potential for the accurate quantitative evaluation of pediatric cardiovascular and pulmonary vascular diseases. Recent pilot studies using pediatric 3-D cardiovascular CT have shown promising results in assessing cardiac function in conditions such as tetralogy of Fallot, cardiac defects with a hypoplastic ventricle, Ebstein anomaly, and in quantifying myocardial mass. In addition, the quantitative assessment of pulmonary vascularity is useful for evaluating differential right-to-left pulmonary vascular volume ratio, the effectiveness of pulmonary angioplasty, and predicting pulmonary hypertension. These initial experiences could broaden the role of pediatric cardiovascular CT in clinical practice. Furthermore, the current barriers to its widespread use, pertinent solutions to these problems, and new applications are discussed. In this review, the 3-D quantitative evaluations of cardiac function and pulmonary vascularity using high-resolution pediatric cardiovascular CT data are illustrated.

Borderline Ventricles: From Evaluation to Treatment

A heart with a borderline ventricle refers to a situation where there is uncertainty about whether the left or right underdeveloped ventricle can effectively support the systemic or pulmonary circulation with appropriate filling pressures and sufficient physiological reserve. Pediatric cardiologists often deal with congenital heart diseases (CHDs) associated with various degrees of hypoplasia of the left or right ventricles. To date, no specific guidelines exist, and surgical management may be extremely variable in different centers and sometimes even in the same center at different times. Thus, the choice between the single-ventricle or biventricular approach is always controversial. The aim of this review is to better define when "small is too small and large is large enough" in order to help clinicians make the decision that could potentially affect the patient's entire life.

Mitral Valve Abnormalities Associated with Single-Ventricle Palliation, Cardiac Death or Transplant in Fetuses with Postnatally Confirmed Coarctation of the Aorta

Predicting if a fetus with borderline left heart structures and coarctation of the aorta (CoA) will require single ventricle palliation (SVP) is challenging, partly due to the limitations of fetal echocardiography in defining valvar abnormalities. Fetal echocardiographic findings predictive of SVP, particularly in relation to the mitral valve (MV), are not well defined. We performed a retrospective review of fetuses with postnatally confirmed CoA from 2010 to 2020. Fetuses with complex congenital heart disease or unequivocal hypoplastic left heart syndrome were excluded. Data were compared between those who underwent biventricular repair (BVR) versus SVP, cardiac death or orthotopic heart transplant (OHT) to determine differences in fetal echocardiograms. Of 67 fetuses with 131 total echocardiograms, 62 (93%) underwent BVR and 5 (7%) experienced SVP, cardiac death or OHT. Fetuses with confirmed CoA who experienced SVP, cardiac death, or OHT, had fetal MV z-scores that were 2.03 lower, on average, than those who underwent BVR (z-score =  - 3.98 vs. - 1.94, 95% CI - 2.93, - 1.13). The incidences of MV anomalies and left to right flow across the foramen ovale were higher in the SVP, cardiac death and OHT group. SVP, cardiac death or OHT in fetuses with confirmed CoA were associated with severe fetal MV hypoplasia, MV anomalies and left to right flow across the foramen ovale. These findings may help guide prenatal counseling about the likelihood of SVP, cardiac death or OHT in fetuses with CoA and borderline left heart structures.

Mitral valve abnormalities associated with single-ventricle palliation, cardiac death or transplant in fetuses with postnatally confirmed coarctation of the aorta

Introduction

Predicting if a fetus with borderline left heart structures and coarctation of the aorta (CoA) will require single ventricle palliation (SVP) is challenging, partly due to the limitations of fetal echocardiography in defining valvar abnormalities. Fetal echocardiographic findings predictive of SVP, particularly in relation to the mitral valve (MV), are not well defined.

Methods

We performed a retrospective review of fetuses with postnatally confirmed CoA from 2010 to 2020. Fetuses with complex congenital heart disease or unequivocal hypoplastic left heart syndrome were excluded. Data were compared between those who underwent biventricular repair (BVR) vs. SVP cardiac death or orthotopic heart transplant (OHT) to determine differences in fetal echocardiograms.

Results

Of 67 fetuses with 131 total echocardiograms, 62 (93%) underwent BVR and 5 (7%) experienced SVP, cardiac death or OHT. Fetuses with confirmed CoA who experienced SVP cardiac death, or OHT, had fetal MV z-scores that were 2.06 lower, on average, than those who underwent BVR (z-score = -3.98 vs. -1.92, 95% CI: -2.96, -1.16). The incidences of MV anomalies and left to right flow across the foramen ovale were higher in the SVP cardiac death and OHT group.

Conclusion

SVP, cardiac death or OHT in fetuses with confirmed CoA were associated with fetal MV hypoplasia, MV anomalies and left to right flow across the foramen ovale. These findings may help guide prenatal counseling about the likelihood of SVP, cardiac death or OHT in fetuses with CoA and borderline left heart structures.

Hybrid Palliation for Hypoplastic Borderline Left Ventricle: One More Chance to Biventricular Repair

Treatment options for hypoplastic borderline left ventricle (LV) are critically dependent on the development of the LV itself and include different types of univentricular palliation or biventricular repair performed at birth. Since hybrid palliation allows deferring major surgery to 4-6 months, in borderline cases, the decision can be postponed until the LV has expressed its growth potential. We aimed to evaluate anatomic modifications of borderline LV after hybrid palliation. We retrospectively reviewed data from 45 consecutive patients with hypoplastic LV who underwent hybrid palliation at birth between 2011 and 2015. Sixteen patients (mean weight 3.15 Kg) exhibited borderline LV and were considered for potential LV growth. After 5 months, five patients underwent univentricular palliation (Group 1), eight biventricular repairs (Group 2) and three died before surgery. Echocardiograms of Groups 1 and 2 were reviewed, comparing LV structures at birth and after 5 months. Although, at birth, all LV measurements were far below the normal limits, after 5 months, LV mass in Group 2 was almost normal, while in Group 1, no growth was evident. However, aortic root diameter and long axis ratio were significantly higher in Group 2 already at birth. Hybrid palliation can be positively considered as a "bridge-to-decision" for borderline LV. Echocardiography plays a key role in monitoring the growth of borderline LV.

Evaluation of right ventricular myocardial deformation properties in fetal hypoplastic left heart by two-dimensional speckle tracking echocardiography

PURPOSE

Right ventricular (RV) function influences the outcome of hypoplastic left heart (HLH) patients. This study aimed to confirm the assumption of prenatal RV remodeling and possible influencing factors of myocardial restructuring using two-dimensional speckle tracking echocardiography (2D STE).

METHODS

This is a retrospective cross-sectional cohort study including HLH fetuses and gestational age-matched controls. Based on a four-chamber view, cine loops were stored with 60 frames per second. Global longitudinal peak systolic strain (GLPSS) of the RV was retrospectively determined and compared to healthy controls. Furthermore, HLH subgroups were built according to the presence of left ventricular endocardial fibroelastosis (LV-EFE) and restrictive foramen ovale (FO) to investigate the effect of these compromising factors on myocardial deformation.

RESULTS

A total of 41 HLH fetuses and 101 controls were included. Gestational age at fetal assessment was similarly distributed in both groups (controls: 26.0 ± 5.6 weeks vs. HLH: 29.1 ± 5.6 weeks). Relating to RV-GLPSS values, fetuses with HLH demonstrated lower mean values than healthy control fetuses (- 15.65% vs. - 16.80%, p = 0.065). Cases with LV-EFE (n = 11) showed significantly lower mean values compared to such without LV-EFE (n = 30) (RV-GLPSS: - 12.12% vs. - 16.52%, p = 0.003). No significant differences were observed for cases with FO restriction (n = 10).

CONCLUSIONS

In HLH the RV undergoes prenatal remodeling, leading to an adaptation of myocardial function to LV conditions. Further explorations by STE should expand knowledge about RV contraction properties in HLH and its impact on surgical outcome.

Imaging of Left Ventricular Hypoplasia

Left ventricular hypoplasia is a common finding in various forms of congenital heart disease. Echocardiography in the setting of left ventricular hypoplasia must comprehensively assess the size and function of all left-sided structures including the mitral valve, left ventricular outflow tract, aortic valve and aortic arch. Of most importance in any variation of left ventricular hypoplasia is the left ventricular inlet. In neonates, the left ventricular inlet often determines the adequacy of the left ventricle and is the most difficult component to treat surgically.

Integrating Novel Physiologic Data into Decision-Making in Congenital Heart Surgery

Optimal decision-making to determine the type and timing of surgical intervention for various congenital heart disease (CHD) requires adequate understanding and interpretation of anatomic and physiologic data obtained from various imaging modalities. Cardiac magnetic resonance (CMR) has revolutionized the way we evaluate the anatomy and physiology of CHD. In addition to 2- and 3-dimensional anatomic data and volumetry, phase-contrast CMR allows quantitative measurements of cardiac output, pulmonary blood flow, pulmonary-to-systemic flow ratio, the amount of intracardiac shunt, valve regurgitation, and aortopulmonary collateral flows. This review article describes the utilization of CMR-derived flow data in surgical decision-making in three distinct subgroups: (1) patients with borderline left ventricle (LV) with emphasis on the ascending aortic flow and other physiologic parameters, (2) single ventricle patients who undergo bidirectional cavopulmonary shunt with emphasis on the impact of superior vena cava blood flow on postoperative physiology, and (3) patients with pulmonary atresia and major aortopulmonary collateral arteries with emphasis on the impact of total pulmonary blood flow and systemic-to-pulmonary flow ratio on clinical outcomes.

Biventricular Conversion for Hypoplastic Left Heart Variants: An Update

Ongoing concerns with single-ventricle palliation morbidity and poor outcomes from primary biventricular strategies for neonates with borderline left heart structures have led some centers to attempt alternative strategies to obviate the need for ultimate Fontan palliation and limit the risk to the child during the vulnerable neonatal period. In certain patients who are traditionally palliated toward single-ventricle circulation, biventricular circulation is possible. This review aims to delineate the current knowledge regarding converting certain patients with borderline left heart structures from single-ventricle palliation toward biventricular circulation.

Fetal echocardiographic predictors of biventricular circulation in hypoplastic left heart complex

OBJECTIVES

To determine which echocardiographic features of hypoplastic left heart complex (HLHC) in the fetal period are predictive of biventricular (BV) circulation and to evaluate the long-term outcome of patients with HLHC, including rates of mortality, reintervention and development of further cardiac disease.

METHODS

Echocardiograms of fetuses with HLHC obtained at 18-26 weeks and 27-36 weeks' gestation between 2004 and 2017 were included in the analysis. The primary outcome was successful BV circulation (Group 1). Group 2 included patients with single-ventricle palliation, death or transplant. Univariate analysis was performed on data obtained at 18-26 and 27-36 weeks and multivariate logistic regression was performed on data obtained at 27-36 weeks only.

RESULTS

Of the 51 included cases, 44 achieved successful BV circulation (Group 1) and seven did not (Group 2). Right-to-left/bidirectional foramen ovale (FO) flow and a higher mitral valve (MV) annulus Z-score were associated with successful BV circulation on both univariate and multivariate analysis. Bidirectional or left-to-right FO flow, left ventricular length (LVL) Z-score of < -2.4 and a MV Z-score of < -4.5 correctly predicted 80% of Group 2 cases. Late follow-up was available for 41 patients. There were two late deaths in Group 2. Thirteen patients in Group 1 required reintervention, 12 developed mitral stenosis and five developed isolated subaortic stenosis.

CONCLUSIONS

BV circulation is common in fetuses with HLHC. Higher MV annulus and LVL Z-scores and right to left direction of FO flow are important predictors of BV circulation. Long-term sequelae in those with BV circulation may include mitral and subaortic stenosis. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

How many types of circulation can a boy have during his life? A case of aortic stenosis with a borderline left ventricle

Severe aortic stenosis can be accompanied by various degrees of left ventricular underdevelopment. The assessment whether a borderline‐sized left ventricle can or cannot support the systemic circulation is crucial. The decision‐making still remains challenging. We present a case that illustrates that the development of haemodynamic parameters can be difficult to estimate, even in the long term. The patient went from biventricular to univentricular circulation and back and could finally be palliated by heart transplantation. Modern technology including long‐term mechanical cardiac support as a bridge to candidacy and drug therapy for pulmonary hypertension were vital to successfully combat a previously lethal disease.

Biventricular Conversion in the Borderline Hypoplastic Heart

PURPOSE OF REVIEW

The development of biventricular repair and conversion pathways for patients with borderline hypoplastic heart disease represents an area of recent inquiry and innovation. This review summarizes emerging techniques and novel treatment algorithms for borderline hypoplastic heart disease with a focus on surgical advances within the last 10 years.

RECENT FINDINGS

Many patients with borderline hypoplastic heart disease are amenable to primary biventricular repair, or biventricular conversion following single-ventricle palliation coupled with ventricular rehabilitation strategies. New insights into the potential for growth and recovery of borderline ventricles have been uncovered. However, questions remain regarding optimal patient selection and the long-term outcomes of select patient groups treated with single-ventricle palliation versus biventricular repair/conversion or transplantation. Efforts to direct a greater proportion of borderline hypoplastic heart patients towards a biventricular circulation are accelerating and represent important avenues for progress and future research in the field of congenital heart disease.

From Fontan to Anatomical Repair 16 Years Later

Decision making for univentricular or anatomical repair remains challenging in children with borderline left ventricle. Unpredictable outcomes have led many caregivers to pursue a single-ventricle strategy. We describe 2 cases of patients with borderline left ventricle initially palliated with univentricular strategy followed by very late conversion to anatomical repair 4 and 16 years later. Anatomical conversion should be considered for these patients even many years later. During the first palliation stages, hemodynamic conditions preserving the potential for growth of the left ventricle should be maintained.

Prediction of biventricular repair by echocardiography in borderline ventricle

Objective:

In recent years, attempting the biventricular pathway or biventricular conversions in patients with borderline ventricle has become a hot topic. However, inappropriate pursuit of biventricular repair in borderline candidates will lead to adverse clinical outcomes. Therefore, it is important to accurately assess the degree of ventricular development before operation and whether it can tolerate biventricular repair. This review evaluated ventricular development using echocardiography for a better prediction of biventricular repair in borderline ventricle.

Data sources:

Articles from January 1, 1990 to April 1, 2019 on biventricular repair in borderline ventricle were accessed from PubMed, using keywords including “borderline ventricle,” “congenital heart disease,” “CHD,” “echocardiography,” and “biventricular repair.”

Study selection:

Original articles and critical reviews relevant to the review's theme were selected.

Results:

Borderline left ventricle (LV): (1) Critical aortic stenosis: the Rhodes score, Congenital Heart Surgeons Society regression equation and another new scoring system was proposed to predict the feasibility of biventricular repair. (2) Aortic arch hypoplasia: the LV size and the diameter of aortic and mitral valve (MV) annulus should be taken into considerations for biventricular repair. (3) Right-dominant unbalanced atrioventricular septal defect (AVSD): atrioventricular valve index (AVVI), left ventricular inflow index (LVII), and right ventricle (RV)/LV inflow angle were the echocardiographic indices for biventricular repair. Borderline RV: (1) pulmonary atresia/intact ventricular septum (PA/IVS): the diameter z-score of tricuspid valve (TV) annulus, ratio of TV to MV diameter, RV inlet length z-score, RV area z-score, RV development index, and RV-TV index, etc. Less objective but more practical description is to classify the RV as tripartite, bipartite, and unipartite. The presence or absence of RV sinusoids, RV dependent coronary circulation, and the degree of tricuspid regurgitation should also be noted. (2) Left-dominant unbalanced AVSD: AVVI, LV, and RV volumes, whether apex forming ventricles were the echocardiographic indices for biventricular repair.

Conclusions:

Although the evaluation of echocardiography cannot guarantee the success of biventricular repair surgery, echocardiography can still provide relatively valuable basis for surgical decision making.

Computed Tomography-Based Ventricular Volumes and Morphometric Parameters for Deciding the Treatment Strategy in Children with a Hypoplastic Left Ventricle: Preliminary Results

Objective

To determine the utility of computed tomography (CT) ventricular volumes and morphometric parameters for deciding the treatment strategy in children with a hypoplastic left ventricle (LV).

Materials and Methods

Ninety-four consecutive children were included in this study and divided into small LV single ventricle repair (SVR) (n = 28), small LV biventricular repair (BVR) (n = 6), disease-matched control (n = 19), and control (n = 41) groups. The CT-based indexed LV volumes, LV-to-right-ventricular (LV/RV) volume ratio, left-to-right atrioventricular valve (AVV) area ratio, left-to-right AVV diameter ratio, and LV/RV long dimension ratio were compared between groups. Proportions of preferred SVR in the small LV SVR group suggested by the parameters were evaluated.

Results

Indexed LV end-systolic (ES) and end-diastolic (ED) volumes in the small LV SVR group (6.3 ± 4.0 mL/m² and 14.4 ± 10.2 mL/m², respectively) were significantly smaller than those in the disease-matched control group (16.0 ± 4.7 mL/m² and 37.7 ± 12.0 mL/m², respectively; p < 0.001) and the control group (16.0 ± 5.5 mL/m² and 46.3 ± 10.8 mL/m², respectively; p < 0.001). These volumes were 8.3 ± 2.4 mL/m² and 21.4 ± 5.3 mL/m², respectively, in the small LV BVR group. ES and ED indexed LV volumes of < 7 mL/m² and < 17 mL/m², LV/RV volume ratios of < 0.22 and < 0.25, AVV area ratios of < 0.33 and < 0.24, and AVV diameter ratios of < 0.52 and < 0.46, respectively, enabled the differentiation of a subset of patients in the small LV SVR group from those in the two control groups. One patient in the small LV biventricular group died after BVR, indicating that this patient might not have been a good candidate based on the suggested cut-off values.

Conclusion

CT-based ventricular volumes and morphometric parameters can suggest cut-off values for SVR in children with a hypoplastic LV.

Modified reverse aortoplasty versus extended anastomosis in patients with coarctation of the aorta and distal arch hypoplasia

OBJECTIVES

The aim of our prospective randomized study was to compare modified reverse aortoplasty (MRA) and extended end-to-end anastomosis (EEA).

METHODS

We have assessed the operative correction results in 54 infants with coarctation of the aorta and distal aortic arch hypoplasia who underwent primary repair in our institute between July 2013 and February 2014. All of the patients were <12 months old when they had the operation. Patients were randomly assigned to 2 arms: modified reverse subclavian flap angioplasty (MRA group; n = 27) or extended end-to-end anastomosis (EEA group; n = 27).

RESULTS

We found a significant difference in residual arterial hypertension between the groups: 2 (7.7%) patients in the MRA group and 8 (30.8%) patients in the EEA group, respectively (P = 0.03). Risk factors for arterial hypertension were precoarctation area rigidity and endocardial fibroelastosis. During the last follow-up visit, recoarctation was observed in 1 (3.8%) patient in the MRA group and in 2 (7.7%) patients in the EEA group, respectively (P = 0.50). Cox regression analysis showed that the only risk factor for recoarctation was the patient's low weight before surgery [odds ratio (95% confidence interval) 0.016 (0.001-0.51), P = 0.047]. An aortic aneurysm developed in 2 (7.7%) patients in the MRA group; however, no significant difference was found between the groups (P = 0.15).

CONCLUSIONS

The results of surgical repair of coarctation of the aorta using modified reverse subclavian flap angioplasty and extended anastomosis were comparable in mortality rates and early postoperative complications. Nevertheless, MRA may be beneficial in reducing residual arterial hypertension at the mid-term follow-up visit.

Serial changes in anatomy and ventricular function on dual-source cardiac computed tomography after the Norwood procedure for hypoplastic left heart syndrome

BACKGROUND

Accurate evaluation of anatomy and ventricular function after the Norwood procedure in hypoplastic left heart syndrome is important for treatment planning and prognostication, but echocardiography and cardiac MRI have limitations.

OBJECTIVE

To assess serial changes in anatomy and ventricular function on dual-source cardiac CT after the Norwood procedure for hypoplastic left heart syndrome.

MATERIALS AND METHODS

In 14 consecutive patients with hypoplastic left heart syndrome, end-systolic and end-diastolic phase cardiac dual-source CT was performed before and early (average: 1 month) after the Norwood procedure, and repeated late (median: 4.5 months) after the Norwood procedure in six patients. Ventricular functional parameters and indexed morphological measurements including pulmonary artery size, right ventricular free wall thickness, and ascending aorta size on cardiac CT were compared between different time points. Moreover, morphological features including ventricular septal defect, endocardial fibroelastosis and coronary ventricular communication were evaluated on cardiac CT.

RESULTS

Right ventricular function and volumes remained unchanged (indexed end-systolic and end-diastolic volumes: 38.9±14.0 vs. 41.1±21.5 ml/m², P=0.7 and 99.5±30.5 vs. 105.1±33.0 ml/m², P=0.6; ejection fraction: 60.1±7.3 vs. 63.8±7.0%, P=0.1, and indexed stroke volume: 60.7±18.0 vs. 64.0±15.6 ml/m², P=0.5) early after the Norwood procedure, but function was decreased (ejection fraction: 64.2±2.6 vs. 58.1±7.1%, P=0.01) and volume was increased (indexed end-systolic and end-diastolic volumes: 39.2±14.9 vs. 68.9±20.6 ml/m², P<0.003 and 107.8±36.5 vs. 162.9±36.2 ml/m², P<0.006, and indexed stroke volume: 68.6±21.7 vs. 94.0±21.3 ml/m², P=0.02) later. Branch pulmonary artery size showed a gradual decrease without asymmetry after the Norwood procedure. Right and left pulmonary artery stenoses were identified in 21.4% (3/14) of the patients. Indexed right ventricular free wall thickness showed a significant increase early after the Norwood procedure (25.5±3.5 vs. 34.8±5.1 mm/m², P=0.01) and then a significant decrease late after the Norwood procedure (34.8±5.1 vs. 27.2±4.2 mm/m², P<0.0001). The hypoplastic ascending aorta smaller than 2 mm in diameter was identified in 21.4% (3/14) of the patients. Ventricular septal defect (n=3), endocardial fibroelastosis (n=2) and coronary ventricular communication (n=1) were detected on cardiac CT.

CONCLUSION

Cardiac CT can be used to assess serial changes in anatomy and ventricular function after the Norwood procedure in patients with hypoplastic left heart syndrome.