Intravascular Ultrasound for Pulmonary Vein Stenosis Interventions in Congenital Heart Disease

Abstract

Objective. Pulmonary vein stenosis (PVS) is aggressive, with high morbidity and mortality. Surgical and catheter interventions yield modest success, at best. Refinements in catheter interventions could potentially improve outcomes in this patient population. The goal of this study was to determine the utility of intravascular ultrasound (IVUS) for patients with congenital heart disease and PVS. Methods. Single-center, retrospective review of patients with congenital heart disease and PVS undergoing diagnostic or interventional catheterizations from March 2015 to February 2020. IVUS of the pulmonary veins was performed using an Eagle Eye Platinum IVUS catheter (Volcano Corporation). Results. Five patients underwent 6 procedures (2 diagnostic, 4 interventional). Median age was 1.5 years (range, 0.7-47.5 years) and weight was 8.8 kg (range, 7.3-61 kg). For the interventional procedures, mean pulmonary vein gradient was 8.7 mm Hg with reduction to 1.1 mm Hg (P<.001). Four patients had congenital PVS and 1 patient was post repair of Scimitar syndrome with an obstructed pulmonary venous baffle. Use of IVUS allowed confirmation of stent expansion and apposition, interval vessel growth after initial stenting, and detection of long-segment hypoplasia, unlikely to respond to intervention. There were no thrombotic complications related to IVUS use. Conclusions. IVUS of the pulmonary veins is safe and easy to perform, and provides detailed imaging of PVS to help guide therapy. For those requiring intervention, adequate stent apposition to the pulmonary vein walls, as well as limiting vessel overdilation, may minimize future in-stent stenosis and need for reintervention in this challenging disease.

J INVASIVE CARDIOL 2021;33(4):E259-E262. Epub 2021 March 3. doi:10.25270/jic/20.00445

Key words: congenital heart disease, IVUS, pulmonary vein stenosis, Scimitar syndrome

Pulmonary vein stenosis (PVS) frequently leads to severe pulmonary hypertension and is an increasing cause of death in patients with congenital heart disease (CHD) after initial interventions.^1,2 Angioplasty alone is often ineffective as a long-term therapy, and there has been an increasing use of stent therapy.^3-5 Disease progression is often rapid, with many patients requiring reintervention within 6 months, likely from neointimal proliferation, so some have proposed the use of drug-eluting stent (DES) implantation as a means of minimizing restenosis.^3,4 Despite this, surgical and transcatheter interventions have modest success at best, and refinements in catheter interventions could potentially improve outcomes.

Intravascular ultrasound (IVUS) has been used in coronary and peripheral vascular interventions to better understand the relationship between implanted stents and vessel walls.^6-8 It has been suggested that better apposition of stents to vessel walls minimizes the risk of overdilation and restenosis from neointimal proliferation.^7,9,10 We hypothesized that the use of IVUS in transcatheter pulmonary vein interventions would provide additional important information to guide the procedure, potentially improving outcomes.

Methods

After approval from the University of Arizona institutional review board, we performed a retrospective review of patients undergoing cardiac catheterization for potential intervention for PVS related to CHD from March 2015 through February 2020. Prior to the interventional catheterizations, each patient was discussed in a multidisciplinary conference and catheter-based intervention was felt to be more appropriate than surgical intervention. As part of the diagnostic catheterization, the left atrium was entered via an existing septal defect or by transseptal puncture. Systemic heparinization was provided to maintain an activated clotting time >250 seconds. Based on prior case reports, and to obtain additional visualization of the affected veins, IVUS of the pulmonary veins was performed using an Eagle Eye Platinum IVUS catheter (Volcano Corporation). The need for intervention was based on hemodynamics, angiography, and IVUS imaging. Data collected included demographics, procedural data, and hemodynamics. Comparisons of non-normally distributed data were made using Mann-Whitney U-test.

Results

Eleven patients underwent 18 catheterizations (8 diagnostic, 10 interventional) for PVS related to CHD during the study period. Demographics are presented in Table 1. IVUS was performed during 6 catheterizations (5 unique patients), with 4 interventions and 2 diagnostic catheterizations; this is the analyzed population for the current study (Table 2). Four patients had congenital PVS and 1 patient was post repair of Scimitar syndrome with an obstructed pulmonary venous baffle. 

For patient #1 (Figures 1A and 1B), angiography and IVUS showed interval vessel growth around a previously placed stent in the left lower pulmonary vein allowing for redilation. It was unclear based on the angiography whether the stent should be dilated further (Figure 1C), but IVUS showed good stent apposition to the vessel wall (Figure 1D) so no additional intervention was performed at that time to avoid overdilation. On follow-up catheterization with IVUS, stenosis was seen in areas no longer covered by the stent due to foreshortening during prior redilation; however, this improved with angioplasty and additional stent placement. 

For patient #2, angiography suggested proximal narrowing of the left upper pulmonary vein that could potentially benefit from stent placement (Figure 2A). IVUS confirmed long-segment hypoplasia with a uniform diameter for the entire length of the vessel that was unlikely to respond to angioplasty or stent placement, so intervention was not undertaken (Figures 2B and 2C).

 For patient #3, narrowing in the mid portion of the obstructed surgical baffle from the anomalous right pulmonary veins to the left atrium was seen well by angiography and IVUS (Figures 3A and 3B). After stent placement, angiography showed improved patency (Figure 3C) and IVUS confirmed excellent stent apposition in the complex, postsurgical pulmonary venous baffle (Figure 3D).

Patient #4 had heterotaxy syndrome, an unbalanced complete atrioventricular septal defect, and had undergone a superior cavopulmonary connection (Glenn procedure) and pulmonary artery banding. She had a 2 mm Hg gradient in the left upper pulmonary vein, but IVUS imaging confirmed uniformly small left pulmonary veins, so no intervention was undertaken.

Patient #5 was noted to have narrowing of the left lower pulmonary vein with a 6 mm Hg gradient at diagnostic catheterization before surgical ventricular septal defect (VSD) closure. This was felt to be due to distortion of the vein secondary to left atrial enlargement from the large left to right ventricular shunt that was expected to resolve after VSD surgery, so no pulmonary vein intervention was undertaken at the time. One year after VSD closure, the pulmonary vein obstruction persisted on echocardiography, so he underwent catheterization for planned PVS intervention. There was still a 5 mm Hg gradient in the left lower pulmonary vein and IVUS confirmed the obstruction was at the entry to the left atrium. Angioplasty and stent placement were performed with complete resolution of the gradient and good apposition of the stent on IVUS.

For the interventional catheterizations, the mean pulmonary vein gradient was 8.7 mm Hg at baseline and 1.1 mm Hg after stent placement (P<.001). All patients recovered well from their procedures and there were no thrombotic complications from performing IVUS. After pulmonary vein stent placement, patients were maintained on daily aspirin, 5 mg/kg/day up to a maximum of 81 mg daily.

Discussion

This case series of the safe use of IVUS during transcatheter pulmonary vein interventions in patients with CHD demonstrates the additional beneficial information that this procedure can provide. IVUS was particularly useful in clarifying anatomic details that were not well defined by angiography alone, including the decision not to intervene on diffusely hypoplastic pulmonary veins. Good apposition of stents to vessel walls has been found to help limit neointimal proliferation and in-stent stenosis, and this is best confirmed using IVUS. Given the progressive, insidious nature of PVS, any method to increase the potential success of intervention is a welcome tool for congenital interventionalists.

Our series is not the first to report the use of IVUS in imaging pulmonary veins, but it is the first to describe its use to guide transcatheter pulmonary vein interventions in patients with CHD. There is one report of using IVUS to confirm the diameter in the left lower pulmonary vein in an adult patient with PVS and to confirm external compression of a pulmonary vein in a child with complex congenital disease noted on a precatheterization computed tomography scan.^11,12 Successful IVUS-guided stent placement has been reported in a 60-year-old patient with PVS after a single-lung transplant and in a 55-year-old patient with pulmonary vein occlusion after catheter ablation for atrial fibrillation.^13,14 

IVUS is used frequently in adult coronary artery diagnostic and interventional procedures, as well as in peripheral vascular interventions.^6,8,15 It allows more detailed imaging of the vessels than standard angiography can provide, particularly in assessing the relationship of implanted stents to the vessel wall.^6-8 Better stent apposition is felt to reduce the risk of neointimal proliferation and improve long-term stent patency.¹⁰ The use of IVUS in pediatric patients has mostly been limited to assessing coronary vasculopathy after Kawasaki disease and orthotopic heart transplant and transcatheter intervention for aortic coarctation.^16-18 This case series highlights the potential utility of IVUS in patients with CHD and PVS. 

This study is limited by its retrospective nature of a single-center experience. Future studies with additional patients and longer follow-up will be necessary to support the routine use of IVUS to guide transcatheter interventions for PVS.

Conclusion

In this series of patients with CHD and PVS, IVUS was helpful in determining the utility and success of transcatheter intervention as well as documenting interval growth of a hypoplastic pulmonary vein after initial intervention. While this is an off-label use and location for IVUS, it was quite safe and provided excellent information to guide the interventions and could be a new tool to use in the treatment of this challenging condition.

References

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From the ¹University of Arizona, Department of Pediatrics, Tucson, Arizona; ²University of Arizona, Department of Medicine, Tucson, Arizona; ³University of Arizona, Department of Pediatrics (Cardiology), Tucson, Arizona.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

The authors report that patient consent was provided for publication of the images used herein.

Manuscript accepted July 17, 2020.

Address for correspondence: Michael D. Seckeler, MD, MSc, University of Arizona, Department of Pediatrics (Cardiology), 1501 N. Campbell Ave, P.O. Box 245073, Tucson AZ, 85724. Email: mseckeler@peds.arizona.edu