Pulmonary Atresia With Intact Ventricular Septum: From Radiofrequency Perforation to Transcatheter Pulmonary Valve

Abstract

Objectives. We intend to describe an entirely transcatheter management pathway for patients with pulmonary atresia with intact ventricular septum (PA/IVS). Background. PA/IVS is a rare cyanotic congenital heart lesion traditionally palliated with multiple procedures and surgeries. Entirely non-surgical transcatheter management from infancy to adulthood may be possible; however, the pathway from neonatal radiofrequency (RF) pulmonary valve perforation to later transcatheter pulmonary valve replacement (TPV) is not well described. Methods. This retrospective study was performed at a pediatric cardiac center between 2007-2018. All patients with PA/IVS who were managed exclusively with catheterization-based interventions as neonates (RF perforation, pulmonary valvuloplasty, or ductal stenting) were analyzed. Demographic, procedural and clinical data were collected. Results. Fifteen patients had exclusively catheterization-based RV decompression as neonates, 7 of whom did not require subsequent surgery. Six patients required a right ventricular outflow tract (RVOT) augmentation later in life; all were born before 2013. All 6 later had a TPV placed. Two of the patients underwent a surgical Glenn shunt alone. Of the 7 patients that never had surgery, 3 have since undergone a TPV, and 4 are awaiting candidacy for TPV placement. No patients with PA/IVS have had an RVOT augmentation at our institution since 2012. Conclusions. Patients with PA/IVS who undergo catheterization-based neonatal interventions can make it to TPV without requiring surgery. At our institution, there has been a shift in management over the last 8 years favoring entirely non-surgical transcatheter management from infancy to adulthood.

Keywords: pulmonary atresia, transcatheter intervention

Pulmonary atresia with intact ventricular septum (PA/IVS) is a rare cyanotic congenital heart lesion traditionally palliated with multiple interventions. There are multiple palliative management pathways, including single ventricle, one-and-a-half ventricle, or biventricular repair. To determine candidacy for a biventricular vs single ventricle circulation, neonates with PA/IVS undergo a thorough evaluation. Typically, this consists of echocardiography and catheterization data; advanced imaging may also be used.¹ Studies have shown that multiple factors influence this decision, including the tricuspid valve z-score, the tricuspid valve to mitral valve ratio, the morphology of the right ventricle (RV) and degree of hypoplasia, and the presence of RV-dependent coronary circulation.^2-5 Patients who are more likely to tolerate opening of the pulmonary valve and decompression of the RV based on these criteria proceed toward biventricular circulations.

Traditionally, the palliation toward a biventricular circulation was done surgically. In the current era, with advances in transcatheter intervention, PA/IVS patients can be managed differently. Neonates safely undergo initial palliation in the catheterization lab via radiofrequency (RF) perforation or balloon dilation through a small opening in their pulmonary valve.^6-8 Stenting of the arterial duct for additional pulmonary blood flow spares the child a neonatal surgical shunt and has been shown to be safe and effective.^9,10 Similar to the cohort of patients managed with neonatal surgeries, these patients demonstrate RV growth over time.^11,12 They can proceed to have either a biventricular circulation or a 1.5 ventricle repair (bidirectional Glenn with antegrade pulmonary blood flow).

Regardless of initial palliation strategy—either surgical or catheterization based—patients frequently develop worsening pulmonary insufficiency and are at risk for RV dilation over time secondary to volume loading. Late surgical pulmonary valve replacement (PVR) for patients with PA/IVS has been shown to be safe, with results comparable to patients with tetralogy of Fallot.¹³ When reviewing the literature over the last 10 years, transcatheter pulmonary valve replacement (TPVR) for patients with PA/IVS has also been reported (Table 1).^13-24 However, an exclusive transcatheter management strategy, from neonatal RF perforation and pulmonary balloon valvuloplasty through later TPVR has not been described in the literature. This study outlines our single-center experience.

Methods

Patient selection. This is a single-center (Rady Children’s Hospital San Diego, California), retrospective study approved by our institutional review board at the University of California, San Diego. As this was a retrospective study, waiver of consent was obtained. All patients between 2007-2018 with PA/IVS who were managed exclusively via catheterization-based interventions as neonates (RF perforation, pulmonary valvuloplasty, and/or ductal stenting) were included. All medical records were reviewed. Demographic, surgical, catheterization, and clinical data of patients were collected and analyzed. Procedural technique, procedural outcomes, adverse events, and follow-up courses are reported.

Data analysis. This is a descriptive study. Categorical data are summarized as count (percentage) and continuous data are summarized as median and range. All statistical analyses were performed using Excel (Microsoft). The authors had full access to the data and take responsibility for data integrity. All authors have read and agree to the manuscript as written.

Results

Fifteen PA/IVS patients underwent exclusively catheterization-based procedures as neonates during the study period (Table 2). All 15 patients (100%) underwent RF perforation and/or balloon valvuloplasty of their pulmonary valve. Twelve patients (80%) required a PDA stent for additional pulmonary blood flow.

Seven patients (47%) did not undergo surgery at any time. Of these, 3 patients (20%) had a TPV placed without ever having surgery and the remaining 4 patients (27%) are future candidates for TPV placement (Figure 1). Two patients (13%) had a stent placed in their right ventricular outflow tract (RVOT).

Six patients (40%) had an RVOT augmentation surgery. All 6 of these patients were born prior to 2013 and all of them had a later TPV placement. The most recent RVOT augmentation surgery performed at our institution was in 2012. Two patients (13%) underwent a surgical bidirectional Glenn shunt only. These 2 patients are both candidates for future TPV placement. Seven patients (47%) have also undergone atrial septal defect device closure.

Regardless of prior catheterization or surgical management strategies, a total of 9 patients (60%) had a TPV placed (Table 3). The median age and weight at TPV placement for these patients was 6 years (range, 4-8) and 19.7 kg (range 17.1-26.4). The most common indications for TPV were moderate to severe pulmonary insufficiency, mild to moderate RV dilation, and exercise intolerance. TPV was successfully implanted in all 9 patients (100%) without major complications. Transient ventricular ectopy was seen in 2 patients (22%), both of whom were placed on nadolol. No recurrence was seen, and the medicine was discontinued as an outpatient in both instances. One patient (11%) developed femoral vein thrombosis on the side used to advance the TPV, which required anticoagulation and repeat catheterization for stenting of the femoral and iliac veins.

Median length of follow-up after TPV placement was 3.4 years (range, 0.3-5.3). All 9 patients (100%) had a functional TPV and were clinically doing well at their latest visit. The degree of pulmonary insufficiency on most recent echocardiogram was trivial or mild in 7 patients (78%) and moderate in 2 patients (22%). All 9 patients (100%) had freedom from bacterial endocarditis. The 6 remaining patients are future potential TPV candidates if indicated.

Discussion

Patients with PA/IVS historically underwent staged palliation with multiple surgical interventions. Those deemed biventricular candidates safely underwent neonatal surgical RV decompression with placement of a surgical shunt. After a period of volume loading and RV growth, they had a surgical PVR. In the current era, individual steps of this palliative process have been more frequently performed via a catheterization procedure. In the neonatal period, RF perforation and balloon dilation of the pulmonary valve with stenting of the ductus arteriosus achieve RV decompression with adequate pulmonary blood flow.^6-10 Later in childhood, TPV has been successfully and safely performed in PA/IVS patients. ^{14-17, 19,20,22} An entirely non-surgical management pathway consisting solely of catheterization-based procedures has not been proposed until now. Our experience shows that PA/IVS patients can complete the entire palliative process without need for any surgical intervention (Figure 2).

Six patients in our series underwent surgical RVOT augmentation. These patients were all born before 2013, in the first half of our study period. This highlights a temporal shift in management strategy at our institution favoring an exclusively catheterization-based approach. The 7 patients in the second half of our study period have never undergone surgery. Three patients have made it through the entire palliative pathway with placement of a TPV. The other 4 patients are awaiting this final step.

For all patients who underwent TPV placement, the procedure was safe, with no major complications. Our numbers are not large enough to make statistical comparisons between patients that had a previous surgery and those that did not. However, after median follow-up of 3.4 years, all patients are clinically doing well, with no observable differences between them. The vast majority (78%) have well-functioning, competent pulmonary valves with less than moderate pulmonary insufficiency seen at the most recent follow-up.

There are numerous factors favoring patients to undergo exclusively catheterization-based palliations. Median sternotomy and neonatal cardiopulmonary bypass are completely avoided. A previous study of PA/IVS patients at our institution showed PDA stenting, when compared with surgical shunts, tended to have a lower mortality rate and less serious acute complications.¹⁰ There were more reinterventions in the PDA stenting cohort. There has not been a study comparing TPVR with surgical PVR in patients with PA/IVS. However, in patients with tetralogy of Fallot who underwent TPV, Daily et al showed less intensive care unit use, shorter intensive care unit length of stay (LOS), mechanical ventilation, and total LOS, as well as less extracorporeal membrane oxygenation use than patients who underwent surgical PVR.²⁵ Similar results may be expected in a PA/IVS patient cohort.

This is a small, retrospective study at a single center. Larger, future studies with longer follow-up time will be beneficial to compare outcomes of patients who undergo an entirely catheterization-based approach with those who have undergone surgery at some point. Extended follow-up duration will also help determine need for and frequency of reinterventions in this subset of patients.

Conclusion

Patients with PA/IVS who undergo catheterization-based neonatal interventions can make it to TPV without requiring surgery at any point. There has been a shift in management at our institution favoring this entirely non-surgical approach.

Affiliations and Disclosures

From the ¹Division of Pediatric Cardiology, Rady Children’s Hospital, San Diego, California; and ²UC San Diego School of Medicine, San Diego, California.

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 consent was provided for publication of the images used herein.

Manuscript accepted June 23, 2022.

Address for correspondence:  Howaida G. El-Said, MD, PhD, Department of Cardiology, Rady Children’s Hospital, 3020 Children’s Way, MC 5004, San Diego, CA 92123. Email: helsaid@rchsd.org

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