Fifteen patients were diagnosed with membranous pulmonary atresia and intact ventricular septum during the study period of 2012–2020. The median age of diagnosis was 4 days (1–34). The median weight was 3.25 Kg (2.5–3.8). All patients presented with cyanosis, with median oxygen saturation of 75% (68–89). Only one patient had prenatal diagnosis of PAIVS. Echocardiographic assessment of the right ventricle showed that 4 patients had well developed, tripartite ventricle, and 11 with hypoplastic ventricle with reasonable inflow and outflow parts, but small trabeculated part. Median tricuspid valve annulus and Z-score were 8.8mm (6.5–11) and − 1.7 (-3.3–0.2), respectively. The median diameter and Z-score of the pulmonary valve annulus were 5.5mm (4-6.5) and − 3.3 (-4.8–1.9), respectively. Eleven patients were started on prostaglandin E-1 infusion after making the diagnosis, three patients were planned for intervention soon after the diagnosis and had oxygen saturation > 80%, therefore did not need prostaglandins, and one patient was transferred to our institution at the age of 34 days with the diagnosis of PAIVS and patent ductus arteriosus (PDA) with no prostaglandin infusion.
All patients underwent attempted pulmonary valve perforation and balloon dilation at a median age of 7 days (2–35). In fourteen patients, the pulmonary valve was perforated successfully using the soft end of an 0.014, hydrophilic tip, complete total occlusion (CTO) coronary wire (Hi-torque Pilot 50, Abbott, Minnesota, USA). Access to the right ventricular outflow tract was achieved using either a 5Fr Judkin right coronary catheter, 4Fr Cobra catheter, or in one case a 5 Fr multipurpose catheter. Once the catheter is in place proximal to the pulmonary valve, the coronary wire was used to perforate the valve with gentle manipulation and rotation of the wire (Fig. 1). In one patient, perforation of the valve could not be done due to failure to achieve a proper catheter position in the outflow tract. Once the wire crossed the pulmonary valve, it was manipulated to either the descending aorta through the PDA, or to a branch pulmonary artery. Balloon dilation was usually done in two steps: First with a small-diameter (2-3mm) coronary balloon. Then, a second balloon whose diameter is selected based on the valve annulus (selected diameter = 1.5x measured valve annulus). Median balloon diameter was 8mm (6–10).
Total of 10 patients (66%) underwent PDA stenting. Six patients underwent PDA stenting at the time of initial procedure concomitantly with pulmonary valve dilation because the right ventricle was believed to be hypoplastic and additional source of pulmonary blood flow was needed. PDA stenting was done via femoral venous approach following the pulmonary valvuloplasty. The one patient in whom pulmonary valve perforation failed, PDA stenting was done via femoral arterial approach. Among the other 8 patients who underwent balloon dilation alone at the initial procedure, three required PDA stenting 7 days later due to persistence of hypoxia and the need to restart prostaglandin E-1 infusion; two underwent stenting via femoral vein approach, and one via femoral arterial approach. Five patients who underwent initial balloon dilation alone did not require further interventions or prostaglandin infusion. All stents used were balloon expandable coronary stents, with diameter of 3.5-4 mm. Length was determined based on angiographic imaging of the PDA, so that both aortic and pulmonary ends are covered (Fig. 2). Two patients required an immediate second stent placement, one to cover the aortic end of the PDA because the initial stent was a few millimeters short, the other one to stabilize the initial stent that partially migrated to the pulmonary trunk. All patients with stents were given antiplatelet dose of aspirin for several months, and stopped once the patient has normal oxygen saturation, and with no right to left shunting at the patent foramen ovale, or if the stent had spontaneously occluded.
Complications, Follow up and outcome:
Oxygen saturation improved from 75% (± 6) before the intervention to 87% (± 3.4), p = 0.0001. One patient who had balloon dilation alone died one day after the procedure despite improved oxygen saturation to 88% on room air, later blood culture grew gram negative bacilli. Three patients had wire perforation to the pericardial space which was immediately recognized, the wire was retracted, repositioned and perforation of the valve was done with no further complications, no pericardial effusion was noted following the procedure in any patient. One patient who had balloon dilation alone was diagnosed with enterococcus infective endocarditis of the pulmonary valve at the age of 2 months, and treated successfully with 6 weeks of intravenous antibiotics. One patient had stent migration to the pulmonary trunk during implantation, which was stabilized with a second stent. Later, the protruding part of the initial stent fractured and the fractured piece resided in the proximal right pulmonary artery, with no effect on the flow. Close follow up was done, lastly at the age of 24 months which showed stable stent position, with normal flow in both branch pulmonary arteries and trivial PDA flow. One patient developed late stent migration and in-stent stenosis at the aortic end of the PDA, requiring a second stent implantation 5 weeks after the initial procedure, later he underwent superior cavo-pulmonary palliation at the age of 5 months.
Follow up for 14 patients who survived was done for a median duration of 34 months (21–100). Twelve patients had two-ventricular outcome, one patient whose initial TV z score was − 2.16 ended up with 1.5 ventricular outcome with a superior cavo-pulmonary connection procedure done at the age of 5 months. His last follow up was at the age of 22 months with oxygen saturation of 97%. One patient with initial TV z score of -2.31 ended up with single ventricular outcome due to severe right ventricular hypoplasia without significant growth despite successful initial procedure, the patient went on to have superior cavo-pulmonary connection procedure with occlusion of the pulmonary valve at the age of 6 months, with last follow up at age of 5.5 years and oxygen saturation of 70% awaiting total cavo-pulmonary palliation. One patient required surgical valvuloplasty of the tricuspid and right ventricular outflow tract augmentation at the age of 8 months. Her last follow up at age 29 months showed two ventricular outcome with mild pulmonary stenosis. One patient required percutaneous atrial septal defect closure at the age of 5 years. Data on patients’ outcomes is summarized in Fig. 3.
Evaluation of tricuspid valve on the last follow up (for surviving patients with two-ventricular outcome, N = 12) showed improved annulus z-score from − 1.4 (± 0.83) to -0.83 (± 0.80), p = 0.042. Patients had either mild tricuspid regurgitation (8), or no regurgitation (4). Pulmonary valve evaluation showed median peak gradient measured by echocardiography of 14 mm Hg (9–29). Seven patients had mild or trivial insufficiency, 5 patients with moderate, and one patient with severe insufficiency.
Regarding stent patency; Four stents had spontaneous occlusion by the time of last follow up, three stents were already removed or ligated surgically during the subsequent surgical interventions (for the patients with uni-ventricular outcome, and 1.5-ventricular outcome, and the patient who needed surgical valvuloplasty of tricuspid and pulmonary valve), and three stents were still patent with trivial insignificant flow.