Living-donor single-lobe lung transplantation for pulmonary hypertension due to alveolar capillary dysplasia with misalignment of pulmonary veins

Clinical Relevance of Rapid FOXF1-Targeted Sequencing in Patients Suspected of Alveolar Capillary Dysplasia With Misalignment of Pulmonary Veins

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal congenital lung disorder that presents shortly after birth with respiratory failure and therapy-resistant pulmonary hypertension. It is associated with heterozygous point mutations and genomic deletions that involve the FOXF1 gene or its upstream regulatory region. Patients are unresponsive to the intensive treatment regimens and suffer unnecessarily because ACDMPV is not always timely recognized and histologic diagnosis is invasive and time consuming. Here, we demonstrate the usefulness of a noninvasive, fast genetic test for FOXF1 variants that we previously developed to rapidly diagnose ACDMPV and reduce the time of hospitalization.

A Morphomolecular Approach to Alveolar Capillary Dysplasia

Alveolar capillary dysplasia (ACD) is a rare lung developmental disorder leading to persistent pulmonary arterial hypertension and fatal outcomes in newborns. The current study analyzed the microvascular morphology and the underlying molecular background of ACD. One ACD group (n = 7), one pulmonary arterial hypertension group (n = 20), and one healthy con1trol group (n = 16) were generated. Samples of histologically confirmed ACD were examined by exome sequencing and array-based comparative genomic hybridization. Vascular morphology was analyzed using scanning electron microscopy of microvascular corrosion casts. Gene expression and biological pathways were analyzed using two panels on inflammation/kinase-specific genes and a comparison analysis tool. Compartment-specific protein expression was analyzed using immunostaining. In ACD, there was an altered capillary network, a high prevalence of intussusceptive angiogenesis, and increased activity of C-X-C motif chemokine receptor 4 (CXCR4), hypoxia-inducible factor 1α (HIF1A), and angiopoietin signaling pathways compared with pulmonary arterial hypertension/healthy controls. Histologically, there was a markedly increased prevalence of endothelial tyrosine kinase receptor (TEK/TIE2)⁺ macrophages in ACD, compared with the other groups, whereas the CXCR4 ligand CXCL12 and HIF1A showed high expression in all groups. ACD is characterized by dysfunctional capillaries and a high prevalence of intussusceptive angiogenesis. The results indicate that endothelial CXCR4, HIF1A, and angiopoietin signaling as well as TIE2⁺ macrophages are crucial for the induction of intussusceptive angiogenesis and vascular remodeling. Future studies should address the use of anti-angiogenic agents in ACD, where TIE2 appears as a promising target.

Living-donor Segmental Lung Transplantation for Pediatric Patients

OBJECTIVE

The preset study evaluated the outcome of living-donor segmental lung transplantation for pediatric patients.

METHODS

Between August 2009 and May 2021, we performed living-donor segmental lung transplantation in 6 critically ill pediatric patients, including 1 patient on a ventilator alone and another patient on a ventilator and extracorporeal membrane oxygenation (ECMO). There were 4 male and 2 female patients, with a median age of 7 years (range, 4-15 years) and a median height of 112.7 cm (range, 95-125.2 cm). The diagnoses included complications of allogeneic hematopoietic stem cell transplantation (n = 4) and pulmonary fibrosis (n = 2). All patients received bilateral lung transplantation under cardiopulmonary bypass. A basal segment and a lower lobe were implanted in 3 patients, and a basal segment and an S6 segment were implanted in the other 3 patients. In 2 patients, the right S6 segmental graft was horizontally rotated 180° and implanted as the left lung.

RESULTS

Among the 9 segmental grafts implanted, 7 functioned well after reperfusion. Two rotated S6 segmental grafts became congestive, with 1 requiring graft extraction and the other venous repair, which was successful. There was 1 hospital death (14 days) due to sepsis and 1 late death (9 years) due to leukoencephalopathy. The remaining 4 patients are currently alive at 9 months, 10 months, 1.3 years, and 1.9 years.

CONCLUSIONS

Living-donor segmental lung transplantation was a technically difficult but feasible procedure with acceptable outcomes for small pediatric patients with chest cavities that were too small for adult lower lobe implantation.

Meticulous closure of collateral vessels in the perihilar mediastinal pleura to control intraoperative bleeding during lung transplantation for pulmonary hypertension

Background

Massive blood transfusion compensating hemorrhage during lung transplantation (LT) results in primary graft dysfunction (PGD) and worse outcomes after LT. Collateral vessels in the perihilar mediastinal pleura could be the source of hemorrhage during LT in patients with pulmonary hypertension (PH). The purpose of this study was to examine the effect of closure with hemoclips of the vessels in the perihilar mediastinal pleura on the risk of intraoperative hemorrhage and outcomes after LT in patients with PH.

Methods

We retrospectively reviewed 80 patients who underwent LT, including 13 patients with primary PH, 29 patients with secondary PH, and 38 patients with non-PH.

Results

The median number of hemoclips was significantly higher in the primary PH group than in the non-PH group (P=0.0045) or secondary PH group (P=0.0060). The intraoperative blood loss, transfusion volume, maximum PGD grade, and the 30-day and 90-day mortality rates in the primary PH group were equivalent to those in the other two groups.

Conclusions

Meticulous closure of collateral vessels in the perihilar mediastinal pleura during LT in patients with primary PH allowed intraoperative hemorrhage to be controlled and might be associated with acceptable mortality rate in these patients similar to that of LT in patients with other diseases.