Impact of stent implantation on pulmonary artery growth

Long-Term and Multidisciplinary Treatment of Tetralogy of Fallot in Pediatrics

BACKGROUND

Right ventricular outflow tract (RVOT) dysfunction is a long-term postsurgical complication of tetralogy of Fallot (TOF) that needs long-term multidisciplinary treatment.

CASE SUMMARY

We report a case of TOF patient who underwent radical surgical repair in infancy and who presented with pulmonary artery stenosis and pulmonary regurgitation during follow-up. Pulmonary stent placement and percutaneous pulmonary valve implantation (PPVI) were pursued successfully when he was aged 5 and 13 years, respectively.

DISCUSSION

PPVI has been widely used as a minimally invasive treatment alternative to surgical pulmonary valve replacement. This technology has shown significant advantages in pediatric patients to improve RVOT dysfunction, relieve symptoms, optimize hemodynamic parameters, and avoid reintervention.

TAKE-HOME MESSAGE

This case provides a long-term and multidisciplinary strategy for TOF in pediatrics, with a focus on the possibility and effect of PPVI in adolescent patients.

Risk Factors and Outcome of Pulmonary Artery Stenting After Bidirectional Cavopulmonary Connection (BDCPC) in Single Ventricle Circulation

After bidirectional cavopulmonary connection (BDCPC) central pulmonary arteries (PAs) of single ventricle (SV) patients can be affected by stenosis or even closure. Aim of this study is to compare SV patients with and without PA-stent implantation post-BDCPC regarding risk factors for stent implantation and outcome. Single center, retrospective (2006-2021) study of 136 SV consecutive patients with and without PA-stent implantation post-BDCPC. Patient characteristics, risk factors for PA-stent implantation and PA growth were assessed comparing angiographic data pre-BDCPC and pre-TCPC. A total of 40/136 (29%) patients underwent PA-stent implantation at median (IQR) 14 (1.1-39.0) days post-BDCPC. 37/40 (92.5%) underwent LPA-stenting. Multiple regression analysis showed single LV patients to receive less likely PA-stents than single RV patients (OR 0.41; p = 0.05). Reduced LPA/BSA (mm/m2) and larger diameter of neo-ascending aorta pre-BDCPC were associated with an increased likelihood of PA-stent implantation post-BDCPC (OR 0.89, p = 0.03; OR 1.05, p = 0.001). Stent re-dilatation was performed in 36/40 (89%) after 1 (0.8-1.5) year. Pulmonary artery diameters pre-BDCPC were lower in the PA-stent group: McGoon (p < 0.001), Nakata (p < 0.001). Indexed pulmonary artery diameters increased equally in both groups but remained lower pre-TCPC in the PA-stent group: McGoon (p < 0.001), Nakata (p = 0.009), and Lower Lobe Index (p = 0.003). LPA and RPA grew symmetrically in both groups. Single RV, larger neo-ascending aorta, and small LPA pre- BDCPC are independent risk factors for PA-stent implantation post-BDCPC. Pulmonary artery diameters after PA-stent implantation and stent re-dilatation showed significant growth together with the contralateral side, but the PA-system remained symmetrically smaller in the stent group.

Stenting of branch pulmonary artery stenosis in children: initial experience and mid-term follow-up of the pul-stent

Not all stents are suitable for children. For instance, premounted stents can be used in infants and small children but cannot dilate with age to accommodate adult-sized pulmonary arteries. Conversely, the Pul-Stent adapts to somatic growth. Thus, our hospital implemented the Pul-Stent in pediatric patients with branch pulmonary artery stenosis. This study summarizes our initial experience with Pul-Stents in this patient population, including the efficacy and safety. We implanted 37 Pul-Stents in 35 patients between August 2014 and June 2015. The patients' mean age and weight at stent implantation were 6.7 ± 3.0 years and 20.9 ± 8.7 kg, respectively. Bench testing revealed that axial shortening of the Pul-Stent was minimal with further dilation, and the radial strength did not change. The stents were successfully deployed in all cases, except two with minor malpositioning. Primarily, 8-12 mm mounting balloons were used for the initial implantation, and a long sheath (8-10 F) was used for delivery. After stent implantation, the minimal lumen diameter in the stenosed segment increased by 50% in 97% (34/35) of patients. Furthermore, the pressure gradient across the stenosed segment decreased by 50% in 77% (23/30) of biventricular patients. One stent fracture and one stent restenosis were noted during the follow-up visits (mean follow-up time: 4.6 ± 1.7 years). Eighteen patients (51%) underwent repeat catheterization; ten had successful redilation. No aneurysms or stent fractures were observed. Our initial results indicate that the Pul-Stent is safe and effective in pediatric patients and can be further dilated over time to accommodate somatic growth. Moreover, the Pul-Stent has good compliance and adequate radial strength to treat pulmonary artery stenosis effectively.

Impact of Transcatheter Pulmonary Artery Intervention Following Superior Cavopulmonary Connection on Pulmonary Artery Growth

INTRODUCTION

Balloon and stent angioplasty of the pulmonary arteries (PAs) are frequently performed following superior cavopulmonary connection (SCPC), not only to normalize the caliber of the affected PA but also in hopes of maximizing downstream growth over time. There are limited data on the impact on subsequent PA growth prior to total cavopulmonary connection (TCPC).

METHODS

A single-center, retrospective cohort study was performed on children who underwent transcatheter (TC) PA intervention following SCPC between January 1, 2010, and December 31, 2018. Growth of treated and contralateral PAs was measured at the lobar bifurcation (distal branch PA [DBPA]) and in the proximal lower lobe (lower lobe branch [LLB]) on serial angiograms. Growth rate was evaluated using a mixed-effect model clustered by individual patient with an interaction term for treated PA and time to evaluate for differential growth rates between treated and contralateral PAs.

RESULTS

Thirty-five patients underwent TC PA intervention following SCPC, at a median of 70 days (interquartile range: 19-297 days) postoperatively. Significant growth was seen at both DBPA and LLB for raw (0.8 mm/year, 95% CI: 0.6-1.0, P < .001 for both) and body surface area (BSA) adjusted measures (8.4mm/m²/year, 95% CI: 5.6-11.2, P < .001; 7.9 mm/m²/year, 95% CI: 5.5-10.2, P < .001). The growth rate of the treated vessel was not significantly different from that of the contralateral vessel at the DBPA or LLB positions for raw (P = .71, .70) or BSA-adjusted measurements (P = .86, .64).

CONCLUSION

Transcatheter PA intervention was associated with normal distal PA growth rate relative to the untreated side.

Treatment of Peripheral Pulmonary Artery Stenosis

Peripheral pulmonary artery stenosis (PAS) is an abnormal narrowing of the pulmonary vasculature and can form anywhere within the pulmonary artery tree. PAS is a congenital or an acquired disease, and its severity depends on the etiology, location, and number of stenoses. Most often seen in infants and young children, some symptoms include shortness of breath, fatigue, and tachycardia. Symptoms can progressively worsen over time as right ventricular pressure increases, leading to further complications including pulmonary artery hypertension and systolic and diastolic dysfunctions. The current treatment options for PAS include simple balloon angioplasty, cutting balloon angioplasty, and stent placement. Simple balloon angioplasty is the most basic therapeutic option for proximally located PAS. Cutting balloon angioplasty is utilized for more dilation-resistant PAS vessels and for more distally located PAS. Stent placement is the most effective option seen to treat the majority of PAS; however, it requires multiple re-interventions for serial dilations and is generally reserved for PAS vessels that are resistant to angioplasty.

Pulmonary artery and lung parenchymal growth following early versus delayed stent interventions in a swine pulmonary artery stenosis model

OBJECTIVES

Compare lung parenchymal and pulmonary artery (PA) growth and hemodynamics following early and delayed PA stent interventions for treatment of unilateral branch PA stenosis (PAS) in swine.

BACKGROUND

How the pulmonary circulation remodels in response to different durations of hypoperfusion and how much growth and function can be recovered with catheter directed interventions at differing time periods of lung development is not understood.

METHODS

A total of 18 swine were assigned to four groups: Sham (n = 4), untreated left PAS (LPAS) (n = 4), early intervention (EI) (n = 5), and delayed intervention (DI) (n = 5). EI had left pulmonary artery (LPA) stenting at 5 weeks (6 kg) with redilation at 10 weeks. DI had stenting at 10 weeks. All underwent right heart catheterization, computed tomography, magnetic resonance imaging, and histology at 20 weeks (55 kg).

RESULTS

EI decreased the extent of histologic changes in the left lung as DI had marked alveolar septal and bronchovascular abnormalities (p = .05 and p < .05 vs. sham) that were less prevalent in EI. EI also increased left lung volumes and alveolar counts compared to DI. EI and DI equally restored LPA pulsatility, R heart pressures, and distal LPA growth. EI and DI improved, but did not normalize LPA stenosis diameter (LPA/DAo ratio: Sham 1.27 ± 0.11 mm/mm, DI 0.88 ± 0.10 mm/mm, EI 1.01 ± 0.09 mm/mm) and pulmonary blood flow distributions (LPA-flow%: Sham 52 ± 5%, LPAS 7 ± 2%, DI 44 ± 3%, EI 40 ± 2%).

CONCLUSION

In this surgically created PAS model, EI was associated with improved lung parenchymal development compared to DI. Longer durations of L lung hypoperfusion did not detrimentally affect PA growth and R heart hemodynamics. Functional and anatomical discrepancies persist despite successful stent interventions that warrant additional investigation.

Comparison of pulmonary artery dimensions in swine obtained from catheter angiography, multi-slice computed tomography, 3D-rotational angiography and phase-contrast magnetic resonance angiography

Accurate pulmonary artery (PA) imaging is necessary for management of patients with complex congenital heart disease (CHD). The ability of newer imaging modalities such as 3D rotational angiography (3DRA) or phase-contrast magnetic resonance angiography (PC-MRA) to measure PA diameters has not been compared to established angiography techniques. Measurements of PA diameters (including PA stenosis and PA stents) from 3DRA and non-contrast-enhanced PC-MRA were compared to 2D catheter angiography (CA) and multi-slice computed tomography (MSCT) in a swine CHD model (n = 18). For all PA segments 3DRA had excellent agreement with CA and MSCT (ICC = 0.94[0.91-0.95] and 0.92[0.89-0.94]). 3DRA PA stenosis measures were similar to CA and MSCT and 3DRA was on average within 5% of 10.8 ± 1.3 mm PA stent diameters from CA and MSCT. For compliant PA segments, 3DRA was on average 3-12% less than CA (p < 0.05) and MSCT (p < 0.01) for 6-14 mm vessels. PC-MRA could not reliably visualize stents and distal PA vessels and only identified 34% of all assigned measurement sites. For measured PA segments, PC-MRA had good agreement to CA and MSCT (ICC = 0.87[0.77-0.92] and 0.83[0.72-0.90]) but PC-MRA overestimated stenosis diameters and underestimated compliant PA diameters. Excellent CA-MSCT PA diameter agreement (ICC = 0.95[0.93-0.96]) confirmed previous data in CHD patients. There was little bias in PA measurements between 3DRA, CA and MSCT in stenotic and stented PAs but 3DRA underestimates measurements of compliant PA regions. Accurate PC-MRA imaging was limited to unstented proximal PA anatomy.

Routine Surveillance Catheterization is Useful in Guiding Management of Stable Fontan Patients

We developed a Fontan surveillance catheterization protocol as part of routine assessment of stable patients 10 years after Fontan completion. The surveillance catherization includes hemodynamic assessment with inhaled nitric oxide, angiography, liver biopsy, and transcatheter intervention if indicated. We aimed to describe hemodynamic and liver biopsy findings, response to pulmonary vasoreactivity testing, rates of transcatheter intervention, and changes in medical therapy following surveillance catheterization in stable Fontan patients. A single-center retrospective review of Fontan patients undergoing surveillance catheterization between November 2014 and May 2019 was performed. Liver biopsies were independently scored by two pathologists. Sixty-three patients underwent surveillance catheterization (mean age 14.6 ± 3.0 years). The mean Fontan pressure was 11.8 ± 2.1 mmHg. The mean cardiac index was 2.9 ± 0.6 L/min/m2. In the 51 patients who underwent pulmonary vasoreactivity testing, there was a significant decrease in median pulmonary vascular resistance (1.8 [range 0.8-4.1] vs 1.4 [range 0.7-3.0] Wood units × m2; p < 0.001). The mean cardiac index increased (3.0 ± 0.6 vs 3.2 ± 0.7 L/min/m2, p = 0.009). The Fontan pressure did not change significantly. Fifty-seven patients underwent liver biopsy, and all but one showed fibrosis. Nineteen patients (33.3%) demonstrated bridging fibrosis or cirrhosis. Twenty-five patients underwent 34 transcatheter interventions. Pulmonary artery or Fontan stent placement was performed in 19 patients. Phosphodiesterase type 5 inhibitors were initiated in nine patients following surveillance catheterization. Routine surveillance catheterization with liver biopsy in adolescent Fontan patients reveals information that can guide interventional and medical management. Further long-term follow-up and assessment are indicated to assess the benefit of these interventions.

A review: Percutaneous pulmonary artery stenosis therapy: state-of-the-art and look to the future

Stenosis, or narrowing, of the branches of the pulmonary artery is a type of CHD that, if left untreated, may lead to significant complications. Ideally, interventions to treat stenosis occur before significant complications or long-term sequelae take place, often within the first 2 years of life. Treatment depends on specifics of the condition, the presence of other malformations, and age of the child. Research and recent innovation to address these shortcomings have provided physicians with safer and more effective methods of treatment. This has further continued to push the ceiling of pulmonary arterial stenosis treatment available for patients. Despite continuous advancement in angioplasty - such as conventional and cutting balloon - and stenting, each treatment method is not without its unique limitations. New technological developments such as bioresorbable stents can accommodate patient growth and pulmonary artery stenosis treatment. As more than a decade has passed since the review by Bergersen and Lock, this article aims to provide a contemporary summary and investigation into the effectiveness of various therapeutic tools currently available, such as bare metal stents and potential innovations including bioresorbable stents.

Consequences of an early catheter-based intervention on pulmonary artery growth and right ventricular myocardial function in a pig model of pulmonary artery stenosis

OBJECTIVE

To determine the consequences of an early catheter-based intervention on pulmonary artery (PA) growth and right ventricular (RV) myocardial function in an animal model of branch PA stenosis.

BACKGROUND

Acute results and safety profiles of deliberate stent fracture within the pulmonary vasculature have been demonstrated. The long-term impact of early stent intervention and deliberate stent fracture on PA growth and myocardial function is not understood.

METHODS

Implantation of small diameter stents was performed in a pig model of left PA stenosis at 6 weeks (10 kg) followed by dilations at 10 (35 kg) and 18 weeks (65 kg) with intent to fracture and implant large diameter stents. Hemodynamics, RV contractility, and 2D/3D angiography were performed with each intervention. The heart and pulmonary vasculature were histologically assessed.

RESULTS

Stent fracture occurred in 9/12 and implantation of large diameter stents was successful in 10/12 animals with no PA aneurysms or dissections. The final stented PA segment and distal left PA branch origins equaled the corresponding PA diameters of sham controls. Growth of left PA immediately beyond the stent was limited and there was diffuse fibro-intimal proliferation within the distal left and right PA. RV contractility was diminished in the intervention group and the response to dobutamine occurred uniquely via increases in heart rate.

CONCLUSIONS

Early stent intervention in this surgically created PA stenosis model was associated with improved growth of the distal PA vasculature but additional investigation of PA vessel physiology and impact on the developing heart are needed.

Bronchial compression following pulmonary artery stenting in single ventricle lesions: how to prevent, and how to decompress

OBJECTIVES

To assess airway compression during pulmonary artery (PA) intervention in single ventricle (SV) palliation.

BACKGROUND

SV lesions with a prominent neo-aortic root are considered a high risk for branch PA and/or bronchial stenosis. PA stenting is well established, but may result in ipsilateral bronchial compression.

METHODS

Single-centre retrospective analysis of 19 palliated SV patients with branch PA stenosis and close proximity to the ipsilateral main bronchus who underwent cardiac catheterisation at a median age and weight of 8.5 years (0.5-25) and 16.5 kg (6-82) between 12/2011 and 05/2015.

RESULTS

Two of the 19 patients suffered an almost-closed left-main bronchus (LMB) following PA stenting. Fortunately, LMB decompression succeeded in both those patients by re-shaping the PA stents by compressing the chest while splinting the LMB with an inflated balloon. To prevent the other 17 patients from suffering this serious complication, we adopted a thorough preparation strategy: 13 patients underwent safe simultaneous bronchoscopy and cardiac catheterisation; in the remaining 4 patients CT-angiography enabled accurate risk evaluation prior to re-catheterisation.

CONCLUSIONS

In SV lesions accompanied by branch PA stenosis, thorough preparation via cross-sectional imaging is mandatory, including simultaneous bronchoscopy and cardiac catheterisation in selected cases, to rule out any airway compression before considering endovascular stent implantation. If a PA stent's compression has already caused severe bronchial obstruction, our balloon-splinted decompression technique should be considered.

Impact of Percutaneous Interventions for Pulmonary Artery Stenosis in Alagille Syndrome

OBJECTIVE

The study aims to examine acute and midterm outcomes after percutaneous interventions for treatment of pulmonary artery stenosis (PAS) in patients with Alagille Syndrome (ALGS).

BACKGROUND

PAS affects up to two thirds of ALGS patients. Responsiveness to transcatheter therapies may differ from other causes of PAS. To date, there has been no study to evaluate outcomes of transcatheter interventions on PAS exclusively in ALGS.

METHODS

In this single-center series, we reviewed procedural, hemodynamic, and angiographic data from patients with ALGS and PAS from 2007 to 2011 who underwent an interventional catheterization. Minimal luminal diameter (MLD) was assessed pre- and postintervention, and at follow-up catheterization(s) when available. Acute and midterm response to high-pressure balloon angioplasty (HBA), bare metal stent (BMS) placement, and cutting balloon angioplasty (CBA) were assessed.

RESULTS

Nine patients (median age 9.1 years) underwent 16 cardiac catheterizations with 34 interventions performed (20 HBA, 11 BMS, 3 CBA). There was a significant acute increase in MLD for all three modalities (42% HBA, P < .01; 91% BMS, P < .01; 58% CBA, P = .04). Follow-up data were available for 19 treated lesions at a median of 11 months. There was no significant difference in the improvement of MLD from baseline between the HBA and BMS groups, although in contrast to the BMS group, the HBA group showed continued interval vessel growth.

CONCLUSIONS

Transcatheter intervention for PAS in ALGS is generally safe and acutely effective. Although BMS implantation was associated with the greatest immediate improvement in MLD, HBA-treated vessels demonstrate interval growth, whereas BMS-treated lesions do not.

Pulmonary artery stents in the recent era: Immediate and intermediate follow-up

BACKGROUND

Long-term follow-up after stent dilation of native and acquired pulmonary artery stenosis is scarce in the pediatric population. Most cohorts include a myriad of anatomies and associated conditions.

METHOD

In order to establish objective performance criteria, we performed a retrospective review of all patients who underwent unilateral pulmonary artery stenting in biventricular physiology at three centers from June 2006 to June 2011.

RESULTS

Fifty-eight patients received 60 stents with Palmaz Genesis stent used most commonly (78%). Average age at implantation was 10.4 ± 10.3 years and weight 31.6 ± 21.8 kg. The immediate success rate was 98%, with improvement in minimal diameter from 5.1 ± 2 cm to 10.6 ± 3 cm (P < 0.01). There were 10 complications (7 major and 3 minor) and no acute mortality. One-year follow-up studies were available in 48 patients (83%), including echocardiogram (60%), catheterization (28%), MRI (29%), and lung perfusion (31%). Follow-up echocardiogram showed mild increase in stent gradient, from 5.7 ± 6.7 mm Hg post-procedure to 17.1 ± 11.7 mm Hg. Follow-up catheterization showed no significant change in minimal stent diameter (8.8 ± 2.6 to 7.8 ± 2.3 mm), gradient (7.7 ± 8.4 to 12.6 ± 12.2 mm Hg), or right ventricular pressures (43.7 ± 9 to 47.7 ± 10.5 mm Hg). Nine patients (16%) underwent scheduled stent redilation over a period of 12 days to 25 months.

CONCLUSION

In conclusion, stent implantation shows excellent immediate and 1-year follow-up results with maintenance of improved caliber of the stented vessel and lowered right ventricular systolic pressures.