Clinical and Hemodynamic Results After Conversion from Single to Biventricular Circulation After Fetal Aortic Stenosis Intervention

Predictive modeling of endocardial fibroelastosis recurrence in patients with congenital heart disease

BACKGROUND

Endocardial fibroelastosis (EFE) is a major effector in the maldevelopment of the heart in patients with congenital heart disease. Despite successful surgical removal, EFE can redevelop, but the underlying cause of EFE recurrence remains unknown. This study aimed to identify hemodynamic predictors and genetic links to epithelial/endothelial-to-mesenchymal transition (EMT/EndMT) alterations for preoperative risk assessment.

METHODS

We assessed the impact of preoperative hemodynamic parameters on EFE recurrence in a cohort of 92 patients with congenital heart disease who underwent left ventricular (LV) EFE resection between January 2010 and March 2021. Additionally, whole-exome sequencing in 18 patients was used to identify rare variants (minor allele frequency <10-5) in high-expression heart (HHE) genes related to cardiac EMT/EndMT and congenital heart disease.

RESULTS

EFE recurred in 55.4% of patients, within a median of 2.2 years postsurgery. Multivariable analysis revealed specific hemodynamic parameters (mitral valve inflow and area, LV filling pressure, and aortic valve gradient and diameter) as predictors, forming a predictive model with an area under the receiver operating characteristic curve of 0.782. Furthermore, 89% of the patients exhibited damaging variants in HHE genes, with 38% linked to cardiac EMT/EndMT Gene Ontology processes and 22% associated with known congenital heart disease genes. Notably, HHE genes associated with cardiac EMT/EndMT were significantly associated with faster EFE recurrence in a multivariate analysis (hazard ratio, 3.56; 95% confidence interval, 1.24-10.17; P = .018).

CONCLUSIONS

These findings established a predictive scoring system using preoperative hemodynamic parameters for EFE recurrence risk assessment. Alterations in HHE genes, particularly those linked to cardiac EMT/EndMT, exacerbate the risk of recurrence.

Biventricular Repair of Univentricular Heart Lowers Risk of Liver Disease Compared With the Fontan Operation

Background

The Fontan operation is associated with chronic venous hypertension, liver and renal disease, and several other sequelae. The alterative surgical approach, when feasible, a biventricular conversion (BiV), may diminish some of these long-term risks.

Objectives

The aim of this study was to compare long-term outcomes of patients undergoing BiV with those undergoing a destination Fontan operation.

Methods

We identified all patients with univentricular physiology cared for at Boston Children's Hospital between 2007 and 2022 and divided them into those who received BiV or Fontan operations. Outcomes included 10-year incidences of modified major adverse cardiovascular events (MACE), liver dysfunction, renal dysfunction, and transplant-free survival. Outcomes in the 2 groups were compared using propensity matching.

Results

A total of 927 patients were evaluated, 341 BiV and 586 Fontan. Following propensity matching, 258 patients from each group were compared. There were no differences between groups in estimated 10-year freedom from MACE (P = 0.70), transplant-free survival (P = 0.70), or freedom from renal disease (P = 0.60). However, estimated 10-year freedom from liver disease was greater in BiV patients (82% BiV vs 71% Fontan, P = 0.02). Incidence rate per 100 person-years follow-up of surgical interventions and readmissions was higher among BiV patients (10.11 vs 1.85, P < 0.001 and 13.09 vs 9.6, P = 0.002), while catheter-based interventions were higher among Fontan patients (8.41 vs 4.63, P < 0.001).

Conclusions

Among a contemporary cohort of patients with single ventricle anatomy, BiV provide comparable long-term survival and lower risk of liver disease when compared to patients who have undergoing Fontan operations.

Factors associated with morbidity, mortality, and hemodynamic failure after biventricular conversion in borderline hypoplastic left hearts

OBJECTIVE

A subset of patients with borderline hypoplastic left heart may be candidates for single to biventricular conversion, but long-term morbidity and mortality persist. Prior studies have shown conflicting results regarding the association of preoperative diastolic dysfunction and outcome, and patient selection remains challenging.

METHODS

Patients with borderline hypoplastic left heart undergoing biventricular conversion from 2005 to 2017 were included. Cox regression identified preoperative factors associated with a composite outcome of time to mortality, heart transplant, takedown to single ventricle circulation, or hemodynamic failure (defined as left ventricular end-diastolic pressure >20 mm Hg, mean pulmonary artery pressure >35 mm Hg, or pulmonary vascular resistance >6 international Woods units).

RESULTS

Among 43 patients, 20 (46%) met the outcome, with a median time to outcome of 5.2 years. On univariate analysis, endocardial fibroelastosis, lower left ventricular end-diastolic volume/body surface area (when <50 mL/m2), lower left ventricular stroke volume/body surface area (when <32 mL/m2), and lower left:right ventricular stroke volume ratio (when <0.7) were associated with outcome; higher preoperative left ventricular end-diastolic pressure was not. Multivariable analysis demonstrated that endocardial fibroelastosis (hazard ratio, 5.1, 95% confidence interval, 1.5-22.7, P = .033) and left ventricular stroke volume/body surface area 28 mL/m2 or less (hazard ratio, 4.3, 95% confidence interval, 1.5-12.3, P = .006) were independently associated with a higher hazard of the outcome. Approximately all patients (86%) with endocardial fibroelastosis and left ventricular stroke volume/body surface area 28 mL/m2 or less met the outcome compared with 10% of those without endocardial fibroelastosis and with higher stroke volume/body surface area.

CONCLUSIONS

History of endocardial fibroelastosis and smaller left ventricular stroke volume/body surface area are independent factors associated with adverse outcomes among patients with borderline hypoplastic left heart undergoing biventricular conversion. Normal preoperative left ventricular end-diastolic pressure is insufficient to reassure against diastolic dysfunction after biventricular conversion.

Hemodynamic and Anatomic Changes after Fetal Aortic Valvuloplasty are associated with Procedural Success and Postnatal Biventricular Circulation

BACKGROUND

There are minimal data characterizing the trajectory of left heart growth and hemodynamics following fetal aortic valvuloplasty (FAV).

METHODS

This retrospective study included patients who underwent FAV between 2000 and 2019 with echocardiograms performed pre-FAV, immediately post-FAV, and in late gestation.

RESULTS

Of 118 fetuses undergoing FAV, 106 (90%) underwent technically successful FAV, of which 55 (52%) had biventricular circulation. Technically successful FAV was associated with improved aortic valve growth (p<0.001), sustained antegrade aortic arch (AoA) flow (p=0.02), improved mitral valve inflow pattern (p=0.002), and favorable patent foramen ovale (PFO) flow pattern (p=0.004) from pre-FAV to late gestation. Compared to patients with univentricular outcome, patients with biventricular outcome had less decrement in size of the left ventricle (LV) (p<0.001) and aortic valve (p=0.005), as well more physiologic PFO flow (p<0.001) and antegrade AoA flow (p<0.001) from pre-FAV to late gestation. In multivariable analysis, echocardiographic predictors of biventricular outcome were less decline in LV end diastolic dimension (p<0.001), improved PFO flow (p=0.004), and sustained antegrade AoA flow (p=0.002) from pre-FAV to late gestation.

CONCLUSION

Stabilization of left heart growth and improved hemodynamics following successful FAV through late gestation are associated with postnatal biventricular circulation. This article is protected by copyright. All rights reserved.

Biventricular conversion after Fontan completion: A preliminary experience

OBJECTIVE

To assess the feasibility and outcomes of biventricular conversion following takedown of Fontan circulation.

METHODS

Retrospective analysis of patients who had takedown of Fontan circulation and conversion to biventricular circulation at a single center from September 2007 to April 2020. Failing Fontan physiology was defined as Fontan circulation pressure >15 mm Hg and/or the presence of associated complications.

RESULTS

Biventricular conversion was performed in 23 patients at a median age of 10.0 (7.5-13.0) years. Indications included failing Fontan physiology in 15 (65%) and elective takedown in 8 (35%) patients. A subset of patients (n = 6) underwent procedures for staged recruitment of the nondominant ventricle before conversion. Median z score of end-diastolic volume of borderline ventricle before takedown was -2.3 (-3.3, -1.3). Hypoplastic left heart syndrome (P < .01) and sub-/aortic stenosis (P < .01) were more common in these patients. Biventricular conversion with or without staged ventricular recruitment led to a significant increase in indexed end-diastolic volume (P < .01), indexed end-systolic volume (P < .01), and ventricular mass (P < .01) of the nondominant ventricle (14 right, 9 left ventricle). There were 5 (22%) deaths (1 [4%] early death). All who underwent elective biventricular conversion survived, whereas 2-year survival rate for patients with a failing Fontan circulation was 72.7% (95% confidence interval, 37%-90%). The overall, 3-year reoperation-free survival was 86.7% (95% confidence interval, 56%-96%). Left dominant atrioventricular canal defect (P < .01) and early era of biventricular conversion (P = .02) were significant predictors for mortality.

CONCLUSIONS

A primary as well as a staged biventricular conversion is feasible in patients who have had previous Fontan procedure. Although this provides an alternative to transplantation in patients with failing Fontan, outcomes are worse in those with failing Fontan compared with elective takedown of Fontan circulation. Optimal timing needs further evaluation.

Development of a biventricular conversion program: A new paradigm

BACKGROUND

Borderline small ventricular size or technical issues precluding the use of both ventricles may lead to single ventricle palliation. Fontan complications have led some centers to look for alternatives to the traditional pathway. The objective of this study is to evaluate the essential philosophy and outcomes of a new biventricular (BiV) conversion program.

METHODS

The prospectively collected Children's Memorial Hermann Heart Institute Society of Thoracic Surgeon's Database was retrospectively reviewed between July 2017 and July 2020.

RESULTS

Thirteen patients met inclusion criteria and underwent BiV conversion during that time. The most frequent diagnosis was malposed great arteries and a ventricular septal defect (VSD) in 4 (31%) patients. Seven (54%) patients were in the first interstage, and 1 (8%) patient had already undergone a Fontan operation before their BiV conversion operation. One or more risk factors for single ventricle palliation (genetic syndrome ≥ moderate atrioventricular valve regurgitation ≥ moderate ventricular dysfunction, presence of signs of Fontan failure) were present in 3 (23%) patients. The median left ventricular end diastolic pressure increased from 5.5 mmHg (4-10 mmHg) to 10 mmHg (6-20 mmHg) postoperatively (p < .05). The right ventricular pressure (RVP) was estimated as less than half systemic in all six patients who were able to be estimated. At a median follow-up of 22.6 months (0.3-36.4 months), 12 (92%) patients are alive.

CONCLUSIONS

BiV conversion is feasible with reasonable short-term clinical outcomes. Mortality risk is low, but as seen in other studies, the risk of reintervention is high.

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.

New Trends in Fetal Anesthesia

Fetal anesthesia teams must understand the pathophysiology and rationale for the treatment of each disease process. Treatment can range from minimally invasive procedures to maternal laparotomy, hysterotomy, and major fetal surgery. Timing may be in early, mid-, or late gestation. Techniques continue to be refined, and the anesthetic plans must evolve to meet the needs of the procedures. Anesthetic plans range from moderate sedation to general anesthesia that includes monitoring of 2 patients simultaneously, fluid restriction, invasive blood pressure monitoring, vasopressor administration, and advanced medication choices to optimize fetal cardiac function.

Microstructure of early embryonic aortic arch and its reversibility following mechanically altered hemodynamic load release

In the embryonic heart, blood flow is distributed through a bilaterally paired artery system composed of the aortic arches (AAs). The purpose of this study is to establish an understanding of the governing mechanism of microstructural maturation of the AA matrix and its reversibility, toward the desired macroscopic vessel lumen diameter and thickness for healthy, abnormal, and in ovo repaired abnormal mechanical loading. While matrix-remodeling mechanisms were significantly different for normal versus conotruncal banding (CTB), both led to an increase in vessel lumen. Correlated with right-sided flow increase at Hamburger & Hamilton stages 21, intermittent load switching between collagen I and III with elastin and collagen-IV defines the normal process. However, decreases in collagen I, elastin, vascular endothelial growth factor-A, and fibrillin-1 in CTB were recovered almost fully following the CTB-release model, primarily because of the pressure load changes. The complex temporal changes in matrix proteins are illustrated through a predictive finite-element model based on elastin and collagen load-sharing mechanism to achieve lumen area increase and thickness increase resulting from wall shear stress and tissue strain, respectively. The effect of embryonic timing in cardiac interventions on AA microstructure was established where abnormal mechanical loading was selectively restored at the key stage of development. Recovery of the normal mechanical loading via early fetal intervention resulted in delayed microstructural maturation. Temporal elastin increase, correlated with wall shear stress, is required for continuous lumen area growth.NEW & NOTEWORTHY The present study undertakes comparative analyses of the mechanistic differences of the arterial matrix microstructure and dynamics in the three fundamental processes of control, conotruncal banded, and released conotruncal band in avian embryo. Among other findings, this study provides specific evidence on the restorative role of elastin during the early lumen growth process. During vascular development, a novel intermittent load-switching mechanism between elastin and collagen, triggered by a step increase in wall shear stress, governs the chronic vessel lumen cross-sectional area increase. Mimicking the fetal cardiovascular interventions currently performed in humans, the early release of the abnormal mechanical load rescues the arterial microstructure with time lag.

An Overview of Contemporary Outcomes in Fetal Cardiac Intervention: A Case for High-Volume Superspecialization?

Fetal cardiac interventions (FCI) offer the opportunity to rescue a fetus at risk of intrauterine death, or more ambitiously to alter disease progression. Most of these fetuses require multiple additional postnatal procedures, and it is difficult to disentangle the effect of the fetal procedure from that of the postnatal management sequence. The true clinical impact of FCI may only be discernible in large-volume institutions that can commit to a standardized postnatal approach and have sufficient case volume to overcome their FCI learning curve.

Fetal cardiac interventions: Where do we stand?

Fetal cardiac intervention (FCI) is a novel and evolving technique that allows for in utero treatment of a subset of congenital heart disease. This review describes the rationale, selection criteria, technical features, and current outcomes for the three most commonly performed FCI: fetal aortic stenosis with evolving hypoplastic left heart syndrome (HLHS); HLHS with intact or restrictive atrial septum; and pulmonary atresia with intact ventricular septum, with concern for worsening right ventricular (RV) hypoplasia.