Monocusp valve placement in children with tetralogy of Fallot undergoing repair with transannular patch: A functioning pulmonary valve does not improve immediate postsurgical outcomes

Hemodynamic evaluation of biomaterial-based surgery for Tetralogy of Fallot using a biorobotic heart, in silico, and ovine models

Tetralogy of Fallot is a congenital heart disease affecting newborns and involves stenosis of the right ventricular outflow tract (RVOT). Surgical correction often widens the RVOT with a transannular enlargement patch, but this causes issues including pulmonary valve insufficiency and progressive right ventricle failure. A monocusp valve can prevent pulmonary regurgitation; however, valve failure resulting from factors including leaflet design, morphology, and immune response can occur, ultimately resulting in pulmonary insufficiency. A multimodal platform to quantitatively evaluate the effect of shape, size, and material on clinical outcomes could optimize monocusp design. This study introduces a benchtop soft biorobotic heart model, a computational fluid model of the RVOT, and a monocusp valve made from an entirely biological cell-assembled extracellular matrix (CAM) to tackle the multifaceted issue of monocusp failure. The hydrodynamic and mechanical performance of RVOT repair strategies was assessed in biorobotic and computational platforms. The monocusp valve design was validated in vivo in ovine models through echocardiography, cardiac magnetic resonance, and catheterization. These models supported assessment of surgical feasibility, handling, suturability, and hemodynamic and mechanical monocusp capabilities. The CAM-based monocusp offered a competent pulmonary valve with regurgitation of 4.6 ± 0.9% and a transvalvular pressure gradient of 4.3 ± 1.4 millimeters of mercury after 7 days of implantation in sheep. The biorobotic heart model, in silico analysis, and in vivo RVOT modeling allowed iteration in monocusp design not now feasible in a clinical environment and will support future surgical testing of biomaterials for complex congenital heart malformations.

Systematic Analysis of PTFE Monocusp Leaflet Design in a Patient-Based 3D in-Vitro Model of Tetralogy of Fallot

PURPOSE

Pulmonary valve (PV) monocusp reconstruction in transannular patch (TAP) right ventricular outflow tract (RVOT) repair for Tetralogy of Fallot has variable clinical outcomes across different surgical approaches. The study purpose was to systematically evaluate how monocusp leaflet design parameters affect valve function in-vitro.

METHODS

A 3D-printed, disease-specific RVOT model was tested under three infant physiological conditions. Monocusps were sewn into models with the native main pulmonary artery (MPA) forming backwalls that constituted 40% and 50% of the reconstructed circumference for z-score zero PV annulus and MPA diameters (native PV z-score - 3.52 and - 2.99 for BSA 0.32m2). Various leaflet free edge lengths (FEL) (relative to backwall), positions (relative to PV STJ), and scallop depths were investigated across both models. Pressure gradient, regurgitation, and coaptation were analyzed with descriptive statistics and regression models.

RESULTS

Increasing FEL beyond 100% of the MPA backwall decreased gradient but mildly increased regurgitation to a peak of 25%. Positioning the free edge 2 mm past the STJ mildly increased gradient for each FEL without significantly changing regurgitation compared to STJ placement. Scalloping leaflets trivially affected performance. Pre-folding leaflets improved mobility and slightly reduced gradient.

CONCLUSIONS

Balancing gradient, regurgitation, and oversizing for growth, a set of leaflet designs have been selected for pre-clinical evaluation. Designs with leaflet widths 140-160% in the 40% backwall model (110-120% in the 50% backwall), positioned at or 2 mm past the STJ, demonstrated the best results. The next stage of ex-vivo testing will additionally consider native RVOT distensibility, native leaflet interactions, and TAP characteristics.

Evolution of Pulmonary Valve Management During Repair of Tetralogy of Fallot: A 14-year Experience

BACKGROUND

The optimal repair strategy for tetralogy of Fallot remains controversial. This report presents a 14-year evolution of management of the pulmonary valve (PV) from transannular patch to valve-sparing repair to neovalve creation using living right atrial appendage tissue.

METHODS

A retrospective review of 172 consecutive patients undergoing complete repair for TOF between January 2007 and June 2021 was performed. Clinical and follow-up data were analyzed by repair group. Neopulmonary valve (NPV) creation using right atrial appendage tissue was introduced in 2019. Failure of valve-sparing repair was defined as needing reintervention for recurrent right ventricular outflow tract obstruction (RVOTO).

RESULTS

Median age and weight at repair were 4.9 months and 6 kg, respectively. Median preoperative PV size and z-score were 6.4 mm (5.2-8.3 mm) and -3.2 (-4.1 to -2.1), respectively. Patients who underwent valve-sparing repair had larger PV size and z-score compared with patients who underwent transannular patch procedures (8 mm vs 5.6 mm; -2.1 vs -3.2; both P < .001). There were no hospital mortalities. Overall follow-up was 44 months. At last follow-up, 10% of patients who underwent valve-sparing repair had repeat intervention for recurrent RVOTO. Patients who had failed valve-sparing repair had significantly lower PV z-scores (-2.6 vs -1.9; P = .01). An NPV was used in 8 patients with a median PV z-score of -4 (-4.7 to -3.9). At 6 months, 6 patients (75%) had mild or trivial pulmonary insufficiency after NPV placement.

CONCLUSIONS

Repair of tetralogy of Fallot is a safe operation with excellent outcomes. Valve-sparing repair avoids right ventricular dilation but may fail for RVOTO at a PV z-score <-2. NPV creation offers an alternative option in patients with a small PV.

The American Association for Thoracic Surgery (AATS) 2022 Expert Consensus Document: Management of infants and neonates with tetralogy of Fallot

OBJECTIVE

Despite decades of experience, aspects of the management of tetralogy of Fallot with pulmonary stenosis (TOF) remain controversial. Practitioners must consider newer, evolving treatment strategies with limited data to guide decision making. Therefore, the TOF Clinical Practice Standards Committee was commissioned by the American Association for Thoracic Surgery to provide a framework on this topic, focused on timing and types of interventions, management of high-risk patients, technical considerations during interventions, and best practices for assessment of outcomes of the interventions. In addition, the group was tasked with identifying pertinent research questions for future investigations. It is recognized that variability in institutional experience could influence the application of this framework to clinical practice.

METHODS

The TOF Clinical Practice Standards Committee is a multinational, multidisciplinary group of cardiologists and surgeons with expertise in TOF. With the assistance of a medical librarian, a citation search in PubMed, Embase, Scopus, and Web of Science was performed using key words related to TOF and its management; the search was restricted to the English language and the year 2000 or later. Articles pertaining to pulmonary atresia, absent pulmonary valve, atrioventricular septal defects, and adult patients with TOF were excluded, as well as nonprimary sources such as review articles. This yielded nearly 20,000 results, of which 163 were included. Greater consideration was given to more recent studies, larger studies, and those using comparison groups with randomization or propensity score matching. Expert consensus statements with class of recommendation and level of evidence were developed using a modified Delphi method, requiring 80% of the member votes with 75% agreement on each statement.

RESULTS

In asymptomatic infants, complete surgical correction between age 3 and 6 months is reasonable to reduce the length of stay, rate of adverse events, and need for a transannular patch. In the majority of symptomatic neonates, both palliation and primary complete surgical correction are useful treatment options. It is reasonable to consider those with low birth weight or prematurity, small or discontinuous pulmonary arteries, chromosomal anomalies, other congenital anomalies, or other comorbidities such as intracranial hemorrhage, sepsis, or other end-organ compromise as high-risk patients. In these high-risk patients, palliation may be preferred; and, in patients with amenable anatomy, catheter-based procedures may prove favorable over surgical palliation.

CONCLUSIONS

Ongoing research will provide further insight into the role of catheter-based interventions. For complete surgical correction, both transatrial and transventricular approaches are effective; however, the smallest possible ventriculotomy should be utilized. When possible, the pulmonary valve should be spared; and if unsalvageable, reconstruction can be considered. At the conclusion of the operation, adequate relief of the right ventricular outflow obstruction should be confirmed, and identification of a significant fixed anatomical obstruction should prompt further intervention. Given our current knowledge and the gaps identified, we propose several key questions to be answered by future research and potentially by a TOF registry: When to palliate or proceed with complete surgical correction, as well as the ideal type of palliation; the optimal surgical approach for complete repair for the best long-term preservation of right ventricular function; and the utility, efficacy, and durability of various pulmonary valve preservation and reconstruction techniques.

An In Vitro Circulatory Loop Model of the Pediatric Right Ventricular Outflow Tract as a Platform for Valve Evaluation

PURPOSE

Tetralogy of Fallot and other conditions affecting the right ventricular outflow tract (RVOT) are common in pediatric patients, but there is a lack of quantitative comparison among techniques for repairing or replacing the pulmonary valve. The aim of this study was to develop a robust in vitro system for quantifying flow conditions after various RVOT interventions.

METHODS

An infant-sized mock circulatory loop that includes a 3D-printed RVOT anatomical model was developed to evaluate flow conditions after different simulated surgical repairs. Physiologically correct flow and pressure were achieved with custom compliant tubing and a tunable flow restrictor. Pressure gradient, flow regurgitation, and coaptation height were measured for two monocusp leaflet designs after tuning the system with a 12 mm Hancock valved conduit.

RESULTS

Measurements were repeatable across multiple samples of two different monocusp designs, with the wider leaflet in the 50% backwall model consistently exhibiting lower pressure gradient but higher regurgitation compared to the leaflet in the 40% backwall model. Coaptation height was measured via direct visualization with endoscopic cameras, revealing a shorter area of contact for the wider leaflet (3.3-4.0 mm) compared to the narrower one (4.3 mm).

CONCLUSION

The 3D-printed RVOT anatomical model and in vitro pulmonary circulatory loop developed in this work provide a platform for planning and evaluating surgical interventions in the pediatric population. Measurements of regurgitation, pressure gradient, and coaptation provide a quantitative basis for comparison among different valve designs and positions.

Implantation of monocusp valve prolongs the duration of chest tube drainage in children with tetralogy of fallot after corrective surgery

BACKGROUND

Right ventricular outflow tract obstruction relief is one of the major procedures during the total correction of tetralogy of Fallot (TOF). Pulmonary insufficiency (PI) is usually inevitable after a transannular incision with a patch repair is performed. Therefore, some surgeons advocate to place a monocusp valve within the transannular patch (TAP) in order to decrease the severity of the PI. However, the monocusp valve seemed not be very effective in some patients who underwent the complete TOF repair.

METHODS

Patients who had the classic form of TOF between January 2009 and January 2017 and underwent the corrective surgery with a TAP by the same cardiovascular surgeon were identified for further analysis. Clinical information including demographics at operation, perioperative data, and postoperative outcome were collected retrospectively and compared between the group with and without a monocusp valve.

RESULTS

A total of 24 TOF cases were included in the final analysis, and 16 (66.7%) patients received a monocusp valve placement. The patients' characteristics before and during the surgery were similar between the two groups. The median duration of chest tube drainage after the total correction in the monocusp group was longer than those without the valve (p = 0.04). There was no difference in the immediate postoperative data, including the inflammation/infection status, the duration of mechanical ventilation, and the length of ICU and hospital stay.

CONCLUSION

Implantation of a monocusp valve during the total TOF correction using a TAP did not bring benefit to improve the immediate postoperative outcomes, especially the duration of the pleural drainage. Further study with a prospective design and a larger number of cases is needed.

Transannular patch repair of tetralogy of Fallot with or without monocusp valve reconstruction: a meta-analysis

Background

Tetralogy of Fallot (TOF) is one of the most common cyanotic congenital heart diseases. Pulmonary regurgitation is the most common and severe comorbidity after transannular patch (TAP) repair of TOF patients. It has not been confirmed whether a TAP repair with monocusp valve reconstruction would benefit TOF patients in perioperative period compared to those without monocusp valve reconstruction. The purpose of the study is to review and analyze all clinical studies that have compared perioperative outcomes of TOF patients undergoing TAP repair with or without monocusp valve reconstruction and conduct a preferable surgery.

Methods

Eligible studies were identified by searching the electronic databases. The year of publication of studies was restricted from 2000 till present. The primary outcome was perioperative mortality, and secondary outcomes included cardiopulmonary bypass time, aortic cross-clamp time, ventilation duration, ICU length of stay, hospital length of stay, perioperative right ventricular outflow tract (RVOT) pressure gradient, and moderate or severe pulmonary regurgitation (PR). The meta-analysis and forest plots were drawn using Review Manager 5.3. Statistically significant was considered when p-value ≤ 0.05.

Results

Eight studies were included which consisted of 8 retrospective cohort study and 2 randomized controlled trial. The 10 studies formed a pool of 526 TOF patients in total, in which are 300 undergoing TAP repair with monocusp valve reconstruction (monocusp group) compared to 226 undergoing TAP repair without monocusp valve reconstruction (non-monocusp group). It demonstrated no significant differences between two groups in perioperative mortality (OR = 0.69, 95% CI 0.20–2.41, p = 0.58). It demonstrated significant differences in perioperative cardiopulmonary bypass time (minute, 95% CI 17.93–28.42, p < 0.00001), mean length of ICU stay (day, 95% CI − 2.11–0.76, p < 0.0001), and the degree of perioperative PR (OR = 0.03, 95% CI 0.010.12, p < 0.00001). Significant differences were not found in other secondary outcomes.

Conclusion

Transannular patch repair with monocusp valve reconstruction have significant advantages on decreasing length of ICU stay and reducing degree of PR for TOF patients. Large, multicenter, randomized, prospective studies which focuse on perioperative outcomes and postoperative differences based on long-term follow-up between TAP repair with and without monocusp valve reconstruction are needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-022-01474-6.

Clinical outcome of right ventricle outflow tract management for repair of Tetralogy of Fallot with three contemporary surgical strategies

Objective:

To compare the early operative outcome of TOF repair with three contemporary repair strategies of RVOTO repair i.e. TAP, Mono-cusp construction (MC) in TAP and pulmonary valve repair.

Methods:

Study is performed at Punjab Institute of Cardiology, Lahore from May 2016 to April 2020. Retrospective analysis of data was performed for patient who underwent TOF repair by three different strategies of RVOT repairs during TOF surgery based on z scoring for pulmonary valve annulus. Group-I underwent trans-annular patch repair, while Group-II and III underwent Mono-cusp repair with autologous pericardium and pulmonary valve repair respectively. Analysis of Variance (ANOVA) and Pearson Chi-Square (PCS) statistics were used to compare the three groups for numeric and categorical variables respectively. Post-hoc t-test and Bonferroni correction were performed for numeric data to compare two groups with each other. Chi-square test was used to perform comparison between groups for categorial variables.

Results:

ANOVA for aortic cross clamp time, total CPB time, Post-operative mechanical ventilation time, ICU stay and hospital stay showed statistical difference among all three group with p-value less than 0.05 however post hoc T-test showed this variation is limited to post-operative mechanical ventilation only when groups compared with each other. PCS showed there was difference for incidence of difficult weaning from CPB when all three groups compared while there was no difference in operative mortality with p-value of 0.15. However, Group-II comparison with Group-I showed that weaning from CPB was superior in-Group-II with p-value of 0.016. Group-III showed the best statistics for all operative outcome variables among all three groups. Comparison of incidence of post-operative moderate pulmonary regurgitation before discharge between Group-II and Group-III showed significant difference with p-value of 0.0052.

Conclusion:

PV repair strategy should be employed for RVOT repair of TOF whenever feasible. MC repair showed fewer hours of postoperative mechanical ventilation and higher incidence of easy weaning from CPB when compared to TAP, however its impacts over ICU stay, Hospital stay and operative mortality is not profound in our TOF repair population.

Surgical repair of tetralogy of Fallot using autologous right atrial appendages: short- to mid-term results

OBJECTIVES

The prevention of pulmonary insufficiency (PI) is a crucial part of the tetralogy of Fallot repair. Many techniques have been introduced to construct valves from different materials for the right ventricular outflow tract, including the most commonly constructed monocusp valves. We are introducing a new bicuspid valve made intraoperatively using the autologous right atrial appendage (RAA) to prevent PI in these patients.

METHODS

The RAA valve was constructed and used in 21 patients with tetralogy of Fallot. The effective preservation of the native valve was impossible in all patients because of either a severe valve deformity or a small annulus. The RAA valve was created after ventricular septal defect closure and right ventricular outflow tract myectomy and was covered with a bovine transannular pericardial patch. The perioperative data were evaluated, and the echocardiography results were assessed immediately after operations and in follow-up with a median of 10.5 months. The data were retrospectively compared with 10 other patients with similar demographic data but with only transannular patches.

RESULTS

The mean age of the patients was 13.3 months. No mortality or related morbidity occurred after repair using the RAA valve. The PI severity early after the operation was trivial or no PI in 18 patients, and mild PI was observed in 3 patients, which progressed to moderate PI in one of them in the mean 12-month follow-up period. Fifteen patients had mild or no pulmonary stenosis, while moderate pulmonary stenosis was observed in 6 others. Compared with the other 10 patients with only transannular patches, the RAA valve patients had prolonged operative and clamping times, but no difference in postoperative course and shorter hospital stays. The degree of PI was, of course, significantly less in the RAA valve patients, but pulmonary stenosis was the same.

CONCLUSIONS

The RAA valve construction is a safe and effective technique to prevent PI after the tetralogy of Fallot repair, at least in terms of short- and mid-term results. A longer follow-up period is needed to confirm if this new valve can eliminate or significantly delay the need for pulmonary valve replacement in these patients.

Monocusp Valves Do Not Improve Early Operative Mortality in Tetralogy of Fallot: A Meta-Analysis

Monocusp valves are thought to reduce early operative mortality and morbidity associated with pediatric tetralogy of Fallot repair. As there are no published randomized clinical trials comparing outcomes with and without a monocusp valve, we performed a meta-analysis of observational studies in accordance with established protocols. After systematically searching PubMed, the Cochrane Library, and Google Scholar, 12 studies were included. The operative mortality was compared in 695 patients, and we found no difference between patients with and patients without a monocusp valve. Monocusp valves may not improve operative mortality of tetralogy of Fallot repair in pediatric patients.