Expanding the Horizons for Pulmonary Artery Stenting

Historically, the right heart has not attracted much attention from adult interventional cardiologists, with development of transcatheter therapies on the right ventricular outflow tract and branch pulmonary arteries evolving predominantly under the watch of the congenital interventionalist. However, with the surge of congenital heart disease patients graduating into adulthood and the exponential growth of transcatheter therapies for adult valve disease, the previously accepted position of “whose side of the heart belongs to whom” is being challenged. Most successful adult programs actively promote greater collaboration between adult and congenital interventionalists, ensuring that the patient’s condition and not the patient’s age becomes the focus. This opportunity to collaborate should swing both ways with the advancement of transcatheter interventions on the pulmonary arteries of small infants driven by improvements in stent design for adults by adult interventionalists. It is likely as the importance of the right heart becomes fully realized, particularly with more aggressive medical and surgical therapies for acquired adult lung conditions, the importance of this relationship will only grow. 

In this issue of the Journal of Invasive Cardiology, Sheikh et al present a comprehensive review of the literature evaluating the safety and outcomes of pulmonary artery stenting for adult-onset pulmonary artery stenosis.¹ As the authors rightly point out, this is a much rarer condition than pulmonary artery narrowing in children, and is predominantly a consequence of lung transplantation surgery, malignancy, or mediastinitis. Stenting was carried out in just over one-third of those with symptomatic narrowing, and it is unclear if this reflects a lack of experience with stent implantation or a preference for balloon dilation in this cohort of patients. Balloon dilation in childhood pulmonary artery stenoses may provide some relief but high-pressure balloons with or without cutting balloons are often necessary and restenosis rates are not negligible.² Seventeen percent of the cohort required multiple stents with a preponderance of balloon-expandable pre-mounted stents, perhaps reflecting a lack of experience with hand mounting. Interestingly covered stents were not used and it is unclear if pressure-loaded pulmonary arteries with scar are susceptible to disruption in the same high-risk cohorts as seen with stenting for aortic coarctation.³ Indeed, 1 patient developed hemothorax and one wonders whether a covered stent may have prevented this. Obviously proximity to lobar branches must be considered. Gradient relief was impressive, with an average pressure reduction of 36 ± 15 mm Hg. Follow-up was available for just over 60% of the cohort with in-stent restenosis seen in one-quarter of these, predominantly in those stented for fibrosing mediastinits. It is unclear if anti-inflammatory or anti-proliferative agents should be considered in this particular cohort.

Although a literature review does not provide a true reflection of overall practice, this work does provide an insight into outcomes and safety of reported cases of stenting. As suggested by the authors, bias will tend toward reporting of successful cases and this needs to be considered. The background and experience of the operator is also difficult to elucidate from such a report, although the stent choice, particularly the self-expanding stents systems, would suggest a predominant non-congenital interventionalist. Ultimately many of the hard-earned lessons of stenting pulmonary arteries in children and adults⁴ by congenital interventionalists over the past 20 years, including techniques for optimizing stent stability during delivery, do not need to be rediscovered. Collaborative programs focused on outcomes and safety rather than territorial positioning should ensure “reinventing of the wheel” is a phrase left out of our practice.    

References

1.    Sheikh MA, Chowdhury, MA, Moukarbel GV. Safety and clinical outcomes of endovascular treatment of adult onset pulmonary artery stenosis. J Invasive Cardiol. 2016;28:202-208. 

2.    Bergersen L, Gauvreau K, Justino H, et al. Randomized trial of cutting balloon compared with high-pressure angioplasty for the treatment of resistant pulmonary artery stenosis. Circulation. 2011;124:2388-2396. 

3.    Taggart N, Minahan M, Cabalka AK, et al. Immediate outcomes of covered stent placement for treatment or prevention of aortic wall injury associated with coarctation of the Aorta (COAST II). JACC Cardiovasc Interv. 2016;9:484-493. Epub 2016 Feb 17.

4.    Kenny D, Amin Z, Slyder S, Hijazi ZM. Medium-term outcomes for peripheral pulmonary artery stenting in adults with congenital heart disease. J Intervent Cardiol. 2011;24:373-377.

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From ¹Our Lady’s Hospital for Sick Children, Crumlin, Dublin, Ireland; and ²Weill Cornell Medicine-Qatar, Sidra Medical and Research Center, Doha, Qatar. 

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.

Address for correspondence: Damien Kenny, MD, Department of Cardiology, Our Lady’s Hospital for Sick Children, Crumlin, Dublin 12, Ireland. Email: damien.kenny@olchc.ie