Lung transplant is a viable treatment option for patients with congenital and acquired pulmonary vein stenosis

Pediatric Lung Transplantation for Pulmonary Vascular Diseases: Recent Advances and Challenges

Pediatric lung transplantation for pulmonary vascular diseases has seen notable advancements and trends. Medical therapies, surgical options, and bridging techniques like extracorporeal membrane oxygenation and different forms of transplants have expanded treatment possibilities. Current challenges include ensuring patient adherence to post-transplant therapies, addressing complications like primary graft dysfunction and rejection, and conducting further research in less common conditions like pulmonary veno-occlusive disease and pulmonary vein stenosis. In this review article, the authors will explore the advancements, emerging trends, and persistent challenges in pediatric lung transplantation for pulmonary vascular diseases.

De Novo and Progressive Pulmonary Vein Stenosis Following Pediatric Heart Transplantation: A Multicenter Retrospective Study

BACKGROUND

Pulmonary vein stenosis (PVS) is a rare condition in which neointimal proliferation leads to venous and arterial hypertension. Little is known about PVS after heart transplant (HTx) in children. We sought to describe the characteristics and outcomes of children who develop PVS after HTx.

METHODS

We performed a retrospective review of patients ≤18 years old who underwent HTx at two HTx centers between April 2012 and October 2023. Patients with PVS were identified via database queries. Cardiac diagnosis, PVS location and extent, and outcomes were recorded.

RESULTS

Over 11.5 years, 422 patients underwent HTx across both centers. Nineteen patients with PVS (10 male) were identified, 15 with de novo PVS. Sixteen had underlying congenital heart disease (CHD), two with anomalous pulmonary venous return. PVS was diagnosed at a median of 2 months (range 2 weeks to 14 years) after HTx. At time of initial diagnosis, 13 patients had one-vessel PVS. At final follow-up, 7/19 (37%) had increases in the number of vessels involved. Six patients underwent surgery, and nine patients had stent or balloon angioplasty. Two patients were treated for pulmonary hypertension following PVS diagnosis. Three patients died from right heart failure secondary to PVS.

CONCLUSIONS

This is the largest study to describe the characteristics of post-HTx PVS in children. PVS occurs in 4.5% of HTx, and underlying CHD is a strong risk factor. Multiple vessels can be involved and may require catheter-based or surgical intervention. Clinicians must be vigilant in monitoring the development of PVS in this population.

An extreme case of cor triatriatum mimicking hypoplastic left heart syndrome and combined pulmonary vein stenosis

A 65-day-old girl presented to the emergency room with lethargy, requiring emergency venoarterial extracorporeal membrane oxygenation for refractory cardiogenic shock. Initially, hypoplastic left heart syndrome was suspected. However, cor triatriatum with a pinpoint opening on the membrane was diagnosed based on a detailed echocardiographic examination. After membrane resection, the left heart size was restored. However, follow-up echocardiography performed 4 months later showed occlusion of both upper pulmonary veins and stenosis in both lower pulmonary veins. Hybrid balloon angioplasty was performed in all pulmonary veins, and stents were inserted into the right upper and lower pulmonary veins. Despite repeated balloon angioplasty, all pulmonary vein stenosis progressed over 6 months and the patient expired while waiting for a heart-lung transplant. Even after successful repair of cor triatriatum, short-term close follow-up is required for detecting the development of pulmonary vein stenosis.

Surgery for fibrosing mediastinitis with severe pulmonary hypertension due to pulmonary venous stenosis

A 21-year-old woman with severe pulmonary hypertension and circulatory collapse was referred to our hospital for possible lung transplantation with extracorporeal membrane oxygenation support. Computed tomography revealed severe stenosis of all 4 pulmonary veins, and fibrosing mediastinitis was suspected. Surgical reconstruction of the pulmonary veins was performed, and extracorporeal membrane oxygenation support was weaned off. After surgery, pulmonary vascular resistance normalized. This successful case demonstrates that surgical pulmonary venous reconstruction is an important treatment for fibrosing mediastinitis induced by pulmonary venous stenosis and pulmonary hypertension.

Pulmonary vein stenosis: Anatomic considerations, surgical management, and outcomes

OBJECTIVE

The study objective was to evaluate outcomes of pulmonary vein stenosis repair in a large single-center cohort.

METHODS

Clinical data from a pulmonary vein stenosis registry were retrospectively reviewed identifying patients who underwent pulmonary vein stenosis repair. The primary/index operation was defined as the patient's first pulmonary vein stenosis operation during the study period.

RESULTS

Between January 2007 and August 2019, 174 patients underwent pulmonary vein stenosis repair. Bilateral pulmonary vein stenosis occurred in 111 patients (64%); 71 patients (41%) had 4-vessel disease. Fifty-nine patients (34%) had primary pulmonary vein stenosis. Median age was 9 months (interquartile range, 5-27) and weight was 6.5 kg (4.7-10.2). Surgical techniques evolved and included ostial resection, unroofing, reimplantation, sutureless, modified sutureless, and a newer anatomically focused approach of pulmonary vein stenosis resection with lateralization or patch enlargement of the pulmonary vein-left atrium connection. Twenty-three patients (13%) required reoperation. Cumulative 2-year incidence of postoperative transcatheter intervention (balloon dilation ± stenting) was 64%. One-, 2-, and 5-year survivals were 71.2%, 66.8%, and 60.6%, respectively. There was no association between surgery type and reoperation rate (hazard ratio, 2.38, P = .25) or transcatheter intervention (hazard ratio, 0.97, P = .95). The anatomically focused repair was associated with decreased mortality on univariate (hazard ratio, 0.38, P = .042) and multivariable analyses (hazard ratio, 0.19, P = .014). Antiproliferative chemotherapy was also associated with decreased mortality (hazard ratio, 0.47, P = .026).

CONCLUSIONS

This large single-center surgical pulmonary vein stenosis experience demonstrates encouraging midterm results. A new anatomically focused repair strategy aims to alleviate pulmonary vein angulation to minimize turbulence and shows promising early outcomes. Continued follow-up is required to understand longer-term outcomes for this surgical approach.

Primary Pulmonary Vein Stenosis: A New Look at a Rare but Challenging Disease

Primary pulmonary vein stenosis (PPVS) represents a rare but emerging, often progressive heterogeneous disease with high morbidity and mortality in the pediatric population. Although our understanding of PPVS disease has improved markedly in recent years, much remains unknown regarding disease pathogenesis, distinct disease phenotypes, and patient- and disease-related risk factors driving the unrelenting disease progression characteristic of PPVS. In the pediatric population, risk factors identified in the development of PPVS include an underlying congenital heart disease, prematurity and associated conditions, and an underlying genetic or congenital syndrome. Continued improvement in the survival of high-risk populations, coupled with ongoing advances in general PPVS awareness and diagnostic imaging technologies suggest that PPVS will be an increasingly prevalent disease affecting pediatric populations in the years to come. However, significant challenges persist in both the diagnosis and management of PPVS. Standardized definitions and risk stratification for PPVS are lacking. Furthermore, evidence-based guidelines for screening, monitoring, and treatment remain to be established. Given these limitations, significant practice variation in management approaches has emerged across centers, and contemporary outcomes for patients affected by PPVS remain guarded. To improve care and outcomes for PPVS patients, the development and implementation of universal definitions for disease and severity, as well as evidence-based guidelines for screening, monitoring, cardiorespiratory care, and indications for surgical intervention will be critical. In addition, collaboration across institutions will be paramount in the creation of regionalized referral centers as well as a comprehensive patient registry for those requiring pulmonary vein stenosis.

Systemic Sirolimus to Prevent In-Stent Stenosis in Pediatric Pulmonary Vein Stenosis

Evaluate the efficacy of systemic sirolimus (rapamycin) in preventing in-stent stenosis (ISS) in pediatric intraluminal pulmonary vein stenosis (PVS). Report the adverse events related to sirolimus therapy. There is a high incidence of ISS following stent implantation in PVS. The use of sirolimus in preventing ISS has not been reported. Retrospective review of all patients who received sirolimus (8 week course) for treatment of ISS for PVS between January 2013 and June 2018. Forty stents (37 bare metal, 3 drug-eluting) in 20 patients were treated with sirolimus; 20 at the time of implantation (primary prevention [1P]) and 20 following documented ISS requiring transcatheter reintervention (secondary prevention [2P]). Treated patients were young (median 2 y/o [0.7-5.7]) and most had PVS associated with congenital heart disease (75%, 15/20; 4/15 with TAPVC). In the 1P group, 85% (17/20) of stents were without significant (< 50%) ISS at median of 102 days (range 56-527); the growth rate of ISS in this group was 7.5 ± 7.1%/month. In the 2P group, most stents had a slower growth rate of ISS after sirolimus therapy compared to pre-treatment (median 3.7 [- 0.2 to 13.1] vs. 10.4 [1.3 to 19.5] %/month; p < 0.001). One patient developed pneumonia on drug while concurrently taking another immunosuppressive agent. No other serious adverse events were related to sirolimus therapy. Systemic sirolimus slows the growth rate of ISS following stent implantation in PVS compared to pre-treatment rates and was administered safely in a small number of pediatric patients with complex heart disease.

Lung Injury and Loss of Regulatory T Cells Primes for Lung-Restricted Autoimmunity

Lung transplantation is a life-saving therapy for several end-stage lung diseases. However, lung allografts suffer from the lowest survival rate predominantly due to rejection. The pathogenesis of alloimmunity and its role in allograft rejection has been extensively studied and multiple approaches have been described to induce tolerance. However, in the context of lung transplantation, dysregulation of mechanisms, which maintain tolerance against self-antigens, can lead to lung-restricted autoimmunity, which has been recently identified to drive the immunopathogenesis of allograft rejection. Indeed, both preexisting as well as de novo lung-restricted autoimmunity can play a major role in the development of lung allograft rejection. The three most widely studied lung-restricted self-antigens include collagen type I, collagen type V, and k-alpha 1 tubulin. In this review, we discuss the role of lung-restricted autoimmunity in the development of both early as well as late lung allograft rejection and recent literature providing insight into the development of lung-restricted autoimmunity through the dysfunction of immune mechanisms which maintain peripheral tolerance.

Adjunct Targeted Biologic Inhibition Agents to Treat Aggressive Multivessel Intraluminal Pediatric Pulmonary Vein Stenosis

OBJECTIVE

To evaluate the use of imatinib mesylate with or without bevacizumab targeting neoproliferative myofibroblast-like cells with tyrosine kinase receptor expression, as adjuncts to modern interventional therapies for the treatment of multivessel intraluminal pulmonary vein stenosis (PVS). We describe the 48- and 72-week outcomes among patients receiving imatinib mesylate with or without bevacizumab for multivessel intraluminal PVS.

STUDY DESIGN

This single-arm, prospective, open-label US Food and Drug Administration approved trial enrolled patients with ≥2 affected pulmonary veins after surgical or catheter-based relief of obstruction between March 2009 and December 2014. Drug therapy was discontinued at 48 weeks, or after 24 weeks of stabilization, whichever occurred later.

RESULTS

Among 48 enrolled patients, 5 had isolated PVS, 26 congenital heart disease, 5 lung disease, and 12 both. After the 72-week follow-up, 16 patients had stabilized, 27 had recurred locally without stabilization, and 5 had progressed. Stabilization was associated with the absence of lung disease (P = .03), a higher percentage of eligible drug doses received (P = .03), and was not associated with age, diagnosis, disease laterality, or number of veins involved. Survival to 72 weeks was 77% (37 of 48). Adverse events were common (n = 1489 total), but only 16 were definitely related to drug treatment, none of which were serious.

CONCLUSION

Survival to 72 weeks was 77% in a referral population with multivessel intraluminal PVS undergoing multimodal treatment, including antiproliferative tyrosine kinase blockade. Toxicity specific to tyrosine kinase blockade was minimal.

Persistent Oxygen Requirement beyond Prematurity: A Case of Acquired Pulmonary Vein Stenosis

Acquired pulmonary vein stenosis is a rare cardiac defect and diagnosis can often be challenging, as many cases present with refractory or prolonged oxygen requirement over the expected course. Comorbid conditions can cloud this diagnosis further. Prognosis is poor for most patients. We present a case of idiopathic acquired pulmonary vein stenosis and discuss diagnostics, treatment options, and the need for further collaborative studies.

Therapeutic Utilities of Pediatric Cardiac Catheterization

In an era when less invasive techniques are favored, therapeutic cardiac catheterization constantly evolves and widens its spectrum of usage in the pediatric population. The advent of sophisticated devices and well-designed equipment has made the management of many congenital cardiac lesions more efficient and safer, while providing more comfort to the patient. Nowadays, a large variety of heart diseases are managed with transcatheter techniques, such as patent foramen ovale, atrial and ventricular septal defects, valve stenosis, patent ductus arteriosus, aortic coarctation, pulmonary artery and vein stenosis and arteriovenous malformations. Moreover, hybrid procedures and catheter ablation have opened new paths in the treatment of complex cardiac lesions and arrhythmias, respectively. In this article, the main therapeutic utilities of cardiac catheterization in children are discussed.

Lung Pathology in Pediatric Pulmonary Vein Stenosis

Pulmonary vein stenosis is a rare progressive narrowing of the extrapulmonary pulmonary veins, presenting predominantly in infancy and virtually always lethal. It typically arises following repair of congenital heart disease, particularly anomalous pulmonary venous return. Histologic characterization of pediatric pulmonary vein stenosis, not previously well described, may provide insight into the disease pathobiology. We retrieved archival lung specimens (biopsy, explant, or autopsy) from patients with pediatric pulmonary vein stenosis. Medical records were reviewed. Microscopic examination included hematoxylin and eosin (H&E)-stained slides, and for a subset of patients, elastic, trichrome, smooth-muscle actin, and D2-40. Groups with different clinical disease features were compared using Fisher's exact test. A total of 33 patients (median age, 7 months) had available tissue and 52% had congenital heart disease; 18% were premature. Within the lungs, interlobular septal veins showed thickened muscular coats (in 58%), proliferation/tortuosity (in 6%), and fibromyxoid intimal proliferation (in 3%). Associated arterial hypertensive changes were seen in 30 (91%). The one patient with intrapulmonary venous fibromyxoid intimal proliferation was the only patient with apparent primary familial disease. Lymphangiectasia and arterial medial hypertrophy were histologic features that correlated with clinical grouping. We conclude that in pediatric pulmonary vein stenosis, intrapulmonary pulmonary veins commonly show muscular thickening, best interpreted as venous hypertensive remodeling. Fibromyxoid intimal proliferation resembling that of the extrapulmonary pulmonary veins is uncommon. Awareness of intrapulmonary features in various clinical subtypes of pulmonary vein stenosis may be diagnostically and therapeutically informative considering that current catheter-based and surgical therapy is directed at the extrapulmonary component of pulmonary vein stenosis.

Outcomes of surgery for young children with multivessel pulmonary vein stenosis

OBJECTIVE

We pursued a multimodality approach to the treatment of patients with pulmonary vein stenosis, incorporating sutureless surgical repair, catheter interventions, and adjunctive chemotherapy. We report our outcomes after surgery.

METHODS

Between January 2007 and August 2013, 49 patients with multivessel pulmonary vein stenosis underwent operations at our institution. We retrospectively reviewed data from a pulmonary vein stenosis registry and the medical records.

RESULTS

At the time of the index operation, the median patient age was 6 months (range, 32 days-48 months) and weight was 4.9 kg (range, 2.1-13.4 kg). Fourteen patients (28%) died during the follow-up period (median follow-up was 0.5 years [range, 0.04-4.9 years]). There were 2 deaths (4%) within 30 days. Age at repair <6 months, weight at repair <3 kg, and a preoperative right ventricular systolic pressure < ¾ systemic were found to be associated with mortality. One patient required repeat operation for recurrent stenosis. Thirty-nine patients (80%) underwent postoperative catheterizations. The median number of catheterizations per patient was 2 (range, 0-14). Twenty-nine patients (59%) underwent catheterizations with pulmonary vein intervention. The median number of catheterizations with intervention per patient was 1 (range, 0-14). There were no identifiable associations with need for or number of catheterizations with intervention. Ten patients were listed for lung transplantation: 4 patients were de-listed, 3 patients died waiting, and 3 patients underwent transplant.

CONCLUSIONS

Using a multimodality approach, we observed acceptable early survival after operation in patients with pulmonary vein stenosis, despite the need for catheter reinterventions. Lung transplantation remains a viable option.

The incidence, diagnosis, and management of pulmonary vein stenosis as a complication of atrial fibrillation ablation

PURPOSE

Pulmonary vein isolation (PVI) during ablation of atrial fibrillation (AF) is associated with pulmonary vein stenosis (PVS). Although the reported incidence of PVS has fallen in recent years, the precise rate of PVS is unknown. Coherent guidelines for screening and treatment of PVS are not established. We reviewed literature to investigate the incidence, diagnosis, and management of PVS as a complication of PVI.

METHODS

We reviewed 41 manuscripts that described a total of 4,615 subjects (median, 84 subjects/study).

RESULTS

The incidence of PVS after PVI reported in literature from 1999 to 2004 ranges from 0 to 44% (mean, 6.3%; median, 5.4%), whereas studies after 2004 report an incidence of 0-19% (mean, 2%; median, 3.1%; p < 0.001). PVS symptoms typically occur with reduction of lung perfusion by 20-25%. Variable criteria exist for diagnosis of PVS by magnetic resonance imaging, computed tomography, and perfusion imaging. The restenosis rate for treatment with balloon angioplasty ranges from 30 to 87% (mean, 60%; median, 47%), compared with immediate stenting that ranges from 14 to 57% (mean, 34%; median, 33%).

CONCLUSIONS

Recent peer-reviewed articles suggest that PVI carries a 3-8% risk of developing PVS, but they likely underestimate the incidence of PVS, as specific screening and diagnostic guidelines are not established. Imaging modalities should be used to screen patients after ablation of AF since early recognition of PVS improves treatment outcomes. Treatment with angioplasty and stent placement can improve symptoms and lung perfusion but the benefit of treatment with immediate stent placement remains controversial. It is critical to maintain a high clinical index of suspicion for PVS in at-risk individuals to ensure timely detection and treatment.