Cardiac regeneration in children

Patch Materials for Pulmonary Artery Arterioplasty and Right Ventricular Outflow Tract Augmentation: A Review

Patch augmentation of the right ventricular outflow tract (RVOT) and pulmonary artery (PA) arterioplasty are relatively common procedures in the surgical treatment of patients with congenital heart disease. To date, several patch materials have been applied with no agreed upon clinical standard. Each patch type has unique performance characteristics, cost, and availability. There are limited data describing the various advantages and disadvantages of different patch materials. We performed a review of studies describing the clinical performance of various RVOT and PA patch materials and found a limited but growing body of literature. Short-term clinical performance has been reported for a multitude of patch types, but comparisons are limited by inconsistent study design and scarce histologic data. Standard clinical criteria for assessment of patch efficacy and criteria for intervention need to be applied across patch types. The field is progressing with improvements in outcomes due to newer patch technologies focused on reducing antigenicity and promoting neotissue formation which may have the ability to grow, remodel, and repair.

Late Recovery of Parathyroid Function after Total Thyroidectomy in Children and Adults: Is There a Difference?

BACKGROUND

Parathyroid failure after total thyroidectomy is the commonest adverse event amongst both children and adults. The phenomenon of late recovery of parathyroid function, especially in young patients with persistent hypoparathyroidism, is not well understood. This study investigated differences in rates of parathyroid recovery in children and adults and factors influencing this.

METHODS

A joint dual-centre database of patients who underwent a total thyroidectomy between 1998 and 2018 was searched for patients with persistent hypoparathyroidism, defined as dependence on oral calcium and vitamin D supplementation at 6 months. Demographic, surgical, pathological, and biochemical data were collected and analysed. <F00_Regular>Parathyroid Glands Remaining</F00_Regular> in Situ (PGRIS) score was calculated.

RESULTS

Out of 960 patients who had total thyroidectomy, 94 (9.8%) had persistent hypoparathyroidism at 6 months, 23 (24.5%) children with a median [range] age 10 [0-17], and 71 (75.5%) adults aged 55 [25-82] years, respectively. Both groups were comparable regarding sex, indication, extent of surgery, and PGRIS score. After a median follow-up of 20 months, the parathyroid recovery rate was identical for children and adults (11 [47.8%] vs. 34 [47.9%]; p = 0.92). Sex, extent, and indication for surgery had no effect on recovery (all p > 0.05). PGRIS score = 4 (HR = 0.48) and serum calcium >2.25 mmol/L (HR = 0.24) at 1 month were associated with a decreased risk of persistent hypoparathyroidism on multivariate analysis (p < 0.05).

CONCLUSION

Almost half of patients recovered from persistent hypoparathyroidism after 6 months; therefore, the term persistent instead of permanent hypoparathyroidism should be used. Recovery rates of parathyroid function in children and adults were similar. Regardless of age, predictive factors for recovery were PGRIS score = 4 and a serum calcium >2.25 mmol/L at 1 month.

Surgical strategies for the management of end-stage heart failure in infants and children: A 15-year experience with a patient-tailored approach

End‐stage heart failure (ESHF) in pediatric age is an ongoing challenge. Heart transplantation is the final option, but its long‐term outcomes are still suboptimal in children. An alternative patient‐tailored surgical protocol to manage ESHF in children is described. Retrospective, single‐center analysis of pediatric patients admitted to our institution between April 2004 and February 2021 for ESHF. Our current protocol is as follows: (a) Patients <1 year with isolated left ventricular dysfunction due to dilated cardiomyopathy underwent pulmonary artery banding (PAB). (b) Patients <10 years and <20 kg, who did not meet previous criteria were managed with Berlin Heart EXCOR. (c) Patients >10 years or >20 kg, underwent placement of intracorporeal Heartware. Primary outcomes were survival, transplant incidence, and postoperative adverse events. A total of 24 patients (mean age 5.3 ± 5.9 years) underwent 26 procedures: PAB in 6 patients, Berlin Heart in 11, and Heartware in 7. Two patients shifted from PAB to Berlin Heart. Overall survival at 1‐year follow‐up and 5‐year follow‐up was 78.7% (95%CI = 62%‐95.4%) and 74.1% (95%CI = 56.1%‐92.1%), respectively. Berlin Heart was adopted in higher‐risk settings showing inferior outcomes, whereas a PAB enabled 67% of patients to avoid transplantation, with no mortality. An integrated, patient‐tailored surgical strategy, comprehensive of PAB and different types of ventricular assist devices, can provide satisfactory medium‐term results for bridging to transplant or recovery. The early postoperative period is critical and requires strict clinical vigilance. Selected infants can benefit from PAB that has demonstrated to be a safe bridge to recovery.

Enhancer decommissioning imposes an epigenetic barrier to sensory hair cell regeneration

Adult mammalian tissues such as heart, brain, retina, and the sensory structures of the inner ear do not effectively regenerate, although a latent capacity for regeneration exists at embryonic and perinatal times. We explored the epigenetic basis for this latent regenerative potential in the mouse inner ear and its rapid loss during maturation. In perinatal supporting cells, whose fate is maintained by Notch-mediated lateral inhibition, the hair cell enhancer network is epigenetically primed (H3K4me1) but silenced (active H3K27 de-acetylation and trimethylation). Blocking Notch signaling during the perinatal period of plasticity rapidly eliminates epigenetic silencing and allows supporting cells to transdifferentiate into hair cells. Importantly, H3K4me1 priming of the hair cell enhancers in supporting cells is removed during the first post-natal week, coinciding with the loss of transdifferentiation potential. We hypothesize that enhancer decommissioning during cochlear maturation contributes to the failure of hair cell regeneration in the mature organ of Corti.

Senning With Aortic Translocation and Anatomic Repair for Congenitally Corrected Transposition

BACKGROUND

Anatomic repair for congenitally corrected transposition of the great arteries with ventricular septal defect (VSD) and pulmonic stenosis has been accomplished with atrial switch and Rastelli. Aortic translocation offers a direct left ventricular outflow without an extraanatomic right ventricular-to-pulmonary conduit, which may lead to decreased reoperations. We reviewed our entire experience performing Senning with aortic translocation (SAT).

METHODS

From 2007 to 2017, 8 patients (mean age, 14.1 months; size, 8.86 kg) underwent SAT. Associated anomalies included situs inversus (n = 2), dextrocardia (n = 6), multiple muscular VSDs (n = 2), abnormal or straddling atrioventricular valve chords (n = 5), and branch pulmonary artery stenosis (n = 3). Four of 8 had previous systemic arterial shunts. Mean cardiopulmonary bypass was 487 minutes, and mean cardiac ischemic time was 307 minutes. Additional procedures included repair of branch pulmonary artery stenoses and closure of multiple muscular VSDs.

RESULTS

There was no hospital death. One patient was supported with extracorporeal membrane oxygenation because of junctional tachycardia on postoperative day 5. One patient required pacemaker placement for first-degree heart block. Median hospital length of stay was 31 days. Mean length of follow-up was 52 months. All patients remain well with mild or no aortic regurgitation. The first patient underwent a repeat surgical operation for pulmonary venous baffle obstruction 2 years after SAT.

CONCLUSIONS

Despite the technical complexity, patient outcomes have been satisfactory. We believe SAT provides a superior anatomic repair in these complex defects. Longer-term follow-up is needed regarding late intervention.

Pulmonary Artery Banding for Ventricular Rehabilitation in Infants With Dilated Cardiomyopathy: Early Results in a Single-Center Experience

Background: Pulmonary artery banding (PAB) is reported as an innovative strategy for children with end-stage heart failure (ESHF) to bridge to transplantation or recovery. We report our early experience with PAB to evaluate outcomes, indications, and limitations. Materials and Methods: This is a single-center prospective clinical study, including infants and children admitted for ESHF owing to dilated cardiomyopathy (DCM) with preserved right ventricular function after failure of maximal conventional therapy. All patients underwent perioperative anticongestive medical therapy with ACE inhibitor, beta blocker, and spironolactone. Post-operatively, all patients underwent echocardiographic follow-up to assess myocardial recovery. Results: We selected five patients (four males) who underwent PAB at a median age of 8.6 months (range 3.9-42.2 months), with preoperative ejection fraction (EF) <30%. Sternal closure was delayed in all. One patient did not improve after PAB and underwent Berlin Heart implantation after 33 days, followed by heart transplant after 13 months. Four patients were discharged home on full anticongestive therapy. However, 2 months after discharge, one patient experienced severe acute heart failure secondary to pneumonia, which required mechanical circulatory support, and the patient underwent a successful heart transplant after 21 days. The remaining three patients are doing well at home, 22.4, 16.9, and 15.4 months after PAB. They all underwent elective percutaneous de-banding, 18.5, 4.8, and 10.7 months after PAB. EF increased from 17.7 ± 8.5% to 63.3 ± 7.6% (p = 0.03), and they have all been delisted. Conclusion: Use of PAB may be an effective alternative to mechanical support in selected infants for bridging to transplant or recovery. Better results seem to occur in patients aged <12 months. Further experience and research are required to identify responders and non-responders to this approach.

Recent advances and challenges on application of tissue engineering for treatment of congenital heart disease

Congenital heart disease (CHD) affects a considerable number of children and adults worldwide. This implicates not only developmental disorders, high mortality, and reduced quality of life but also, high costs for the healthcare systems. CHD refers to a variety of heart and vascular malformations which could be very challenging to reconstruct the malformed region surgically, especially when the patient is an infant or a child. Advanced technology and research have offered a better mechanistic insight on the impact of CHD in the heart and vascular system of infants, children, and adults and identified potential therapeutic solutions. Many artificial materials and devices have been used for cardiovascular surgery. Surgeons and the medical industry created and evolved the ball valves to the carbon-based leaflet valves and introduced bioprosthesis as an alternative. However, with research further progressing, contracting tissue has been developed in laboratories and tissue engineering (TE) could represent a revolutionary answer for CHD surgery. Development of engineered tissue for cardiac and aortic reconstruction for developing bodies of infants and children can be very challenging. Nevertheless, using acellular scaffolds, allograft, xenografts, and autografts is already very common. Seeding of cells on surface and within scaffold is a key challenging factor for use of the above. The use of different types of stem cells has been investigated and proven to be suitable for tissue engineering. They are the most promising source of cells for heart reconstruction in a developing body, even for adults. Some stem cell types are more effective than others, with some disadvantages which may be eliminated in the future.

Clinical cardiac regenerative studies in children

Although the incidence of pediatric heart failure is low, the mortality is relatively high, with severe clinical symptoms requiring repeated hospitalization or intensive care treatment in the surviving patients. Cardiac biopsy specimens have revealed a higher number of resident human cardiac progenitor cells, with greater proliferation and differentiation capacity, in the neonatal period as compared with adults, demonstrating the regeneration potential of the young heart, with rising interest in cardiac regeneration therapy in critically ill pediatric patients. We review here the available literature data, searching the MEDLINE, Google Scholar and EMBASE database for completed, and www.clinicaltrials.gov homepage for ongoing studies involving pediatric cardiac regeneration reports. Because of difficulties conducting randomized blinded clinical trials in pediatric patients, mostly case reports or cohort studies with a limited number of individuals have been published in the field of pediatric regenerative cardiology. The majority of pediatric autologous cell transplantations into the cardiac tissue have been performed in critically ill children with severe or terminal heart failure. Congenital heart disease, myocarditis, and idiopathic hypertrophic or dilated cardiomyopathy leading to congestive heart failure are some possible areas of interest for pediatric cardiac regeneration therapy. Autologous bone marrow mononuclear cells, progenitor cells, or cardiospheres have been applied either intracoronary or percutaneously intramyocardially in severely ill children, leading to a reported clinical benefit of cell-based cardiac therapies. In conclusion, compassionate use of autologous stem cell administration has led to at least short-term improvement in heart function and clinical stability in the majority of the critically ill pediatric patients.