Technical Feasibility on the Use of Optical Coherence Tomography in the Evaluation of Pediatric Pulmonary Venous Stenosis

Pulmonary vein stenosis: future optimism

PURPOSE OF REVIEW

Pulmonary vein stenosis (PVS) is a rare disease with high morbidity and mortality. Prevention of restenosis remains challenging. This review will highlight recent advances in therapy that are beginning to show a survival benefit.

RECENT FINDINGS

Intervention for multivessel pediatric PVS may be surgical or transcatheter, both with high restenosis rates. At a threshold upstream diameter of 7 mm, the risk of restenosis decreases. Close vigilance and frequent reinterventions, typically transcatheter, are now accepted practice to maintain vein patency and achieve upstream growth. Suppressive agents targeting the exuberant myofibroblastic proliferation characteristic of PVS, specifically sirolimus, delivered locally on the surface of balloons and stents, and as adjunct systemic therapy, have been shown to increase survival and decrease reinterventions. Newer surgical techniques focused on shortening and straightening the vein to optimize flow dynamics, coupled with hybrid intraoperative stent placement in selected cases, also show a survival benefit.Adult-onset PVS, most commonly a complication of pulmonary vein isolation, now occurs rarely, and generally responds to transcatheter intervention. Further advances in ablation techniques aim to eliminate this complication.

SUMMARY

An aggressive approach of frequent reinterventions is a necessary strategy rather than treatment failure. More granular understanding of the mechanisms underlying PVS leading to novel muti-pronged anatomic and suppressive therapy are yielding improved survival.Multispecialty PVS teams at the institutional level and multiinstitutional collaboration, now possible via the PVS registry, are crucial to optimal care and future progress.

Feasibility of Electric Impedance Tomography in the Assessment of Lung Perfusion and Ventilation in Congenital Pulmonary Vein Stenosis

Pulmonary vein stenosis (PVS) is a complex disease that requires repeated percutaneous interventions. Electrical impedance tomography (EIT) is a functional imaging technique that provides real-time images of pulmonary perfusion and ventilation. We aimed to determine the feasibility of EIT to evaluate ventilation/perfusion in PVS before and after catheter-based interventions. EIT was conducted in patients with PVS using the ACT5 EIT system. Lung regions were segmented from the perfusion images, and time-dependent blood volume curves were computed voxel-wise and by lung region. The distribution of pulmonary blood flow (PBF) was computed from EIT images and compared pre and post intervention. Finally, a blinded interventional cardiologist reviewed the results to evaluate three findings: (1) side and extent of PVS, (2) perfusion, and (3) ventilation. During the study period, twelve patients were included. Of these, seven were female (58.3%) with a median age of 3.5 years. Six patients had history of prematurity, and four had history of previous surgical PVS intervention. Three patients (25%) had an episode of pulmonary hemorrhage during the current intervention. In general, ventilation/perfusion data were successfully obtained in all cases. EIT correctly depicted all 12 cases of PVS correlating with angiography performed on the same day. EIT is a non-invasive, radiation-free technique that estimates lung perfusion/ventilation and percent distribution of PBF. The subject-based evaluation of EIT correlates to the severity and sidedness of the veins involved. This technology has the potential of providing perfusion/ventilation information in-PVS patients without the need of contrast or radiation.

Management of Complex Pulmonary Vein Stenosis at Altitude Combining Comprehensive Percutaneous Interventional Treatment with Sirolimus, Pulmonary Hypertension Medications and Intraluminal Imaging with Optical Coherence Tomography

BACKGROUND

Pulmonary vein stenosis (PVS) is a growing problem for the pediatric congenital heart population. Sirolimus has previously been shown to improve survival and slow down the progression of in-stent stenosis in patients with PVS. We evaluated patients before and after initiation of sirolimus to evaluate its effects on re-intervention and vessel patency utilizing Optical Coherence Tomography (OCT).

METHODS

We performed a retrospective study, reviewing the charts of patients with PVS, who had been prescribed sirolimus between October 2020 and December 2021. OCT was performed in the pulmonary vein of interest as per our published protocol. Angiographic and OCT imaging was retrospectively reviewed. Statistical analysis was performed using Chi square and Wilcoxon signed-rank test to compare pre-and post-sirolimus data.

RESULTS

Ten patients had been started and followed on sirolimus. Median age at sirolimus initiation was 25 months with median weight of 10.6 kg and average follow-up of 1 year. Median total catheterizations were 7 for patients prior to starting sirolimus and 2 after starting treatment (p = 0.014). Comparing pre- and post-sirolimus, patients were catheterized every 3 months vs every 11 months (p = 0.011), median procedure time was 203 min vs 145 min (p = 0.036) and fluoroscopy time, 80 min vs 57.2 min (p = 0.036). 23 veins had severe in-stent tissue ingrowth prior to SST (luminal diameter < 30% of stent diameter). Post-sirolimus, 23 pulmonary veins had moderate to severe in-stent tissue ingrowth that responded to non-compliant balloon inflation only with stent luminal improvement of > 75%.

CONCLUSION

Our study suggests that the addition of sirolimus in patients with moderate-severe PVS helps to decrease disease progression with decrease frequency of interventions. Reaching therapeutic levels for sirolimus is critical and medication interactions and side-effects need careful consideration. OCT continues to be important for evaluation and treatment guidance in this patient population.

Management of Pediatric Pulmonary Vein Stenosis

Pediatric intraluminal pulmonary vein stenosis has evolved into a chronic illness, with improving survival. Although significant knowledge gaps remain, medical providers have found success in the management of patients with pulmonary vein stenosis using a comprehensive multimodality treatment strategy. This review discusses the core principles employed by 4 centers dedicated to improving pulmonary vein stenosis outcomes, including how to make the diagnosis, educating the family, treatment strategy, the importance of surveillance, and the management of symptoms and comorbidities.