Stent implantation in the arterial duct of the newborn with duct-dependent pulmonary circulation: single centre experience from Turkey Free

Abstract

OBJECTIVES

Implantation of stents into the ductus arteriosus is an alternative treatment to palliative or corrective cardiac surgery in newborns with duct-dependent pulmonary circulation, although the use of this technique for congenital heart disease is limited.

METHODS

Between April 2010 and June 2011, 13 patients underwent patent ductus arteriosus stenting after full assessment by echocardiogram and angiogram, two of patients had pulmonary atresia (PA) and ventricular septal defect (VSD), six patients had PA with intact ventricular septum (IVS), four patients had critical pulmonary stenosis with IVS and one single ventricle physiology with PA and four patients had radiofrequency-assisted perforation of the pulmonary valve at the same time. All procedures were retrograde through the femoral artery, except one, which was by the femoral vein approach.

RESULTS

The mean age and weight during intervention were 10.5 ± 5.7 days and 3.1 ± 0.4 kg, respectively. The mean of procedure and scopy time, time of stay in intensive care, total out-of-hospital and total follow-up time were 138.88 ± 67.11 min; 40.32 ± 25.86 min; 4.88 ± 6.07 days; 11.00 ± 6.89 days and 86.40 ± 73.21 days, respectively. The mean of the radiation amount was 1054.27 ± 1106.91 cGy/cm². The mean of saturation before and after intervention were 64.44 ± 5.83; 81.88 ± 6.95%, respectively. Procedure-related deaths were observed in two patients. The causes of death were pulmonary haemorrhage (n = 1) and retroperitoneal haemorrhage (n = 1). Two patients also died after discharge before surgery due to sepsis (n = 1) and aspiration pneumonia (n = 1). Eight of 13 patients achieved stent patency during 6 months of follow up and re-stenosis developed in one patient (1/8; 12.5%) who had undergone a Glenn operation at 4.5 months of age.

CONCLUSIONS

Ductal stenting is a practicable, effective, safer and less invasive method compared palliative or corrective surgery. Patients with ductal stenting have growth of the pulmonary artery which provides additional time for surgical repair. Our data suggested that ductal stenting should be considered as a first treatment step in newborns with duct-depended pulmonary circulation. However, long-term palliation without stent re-stenosismight still be a concern especially in patients with hypoplastic pulmonary arteries.

INTRODUCTION

The possibility of total repair in the early phase of cyanotic congenital heart disease has increased as a result of improvements in surgical technique and intensive care. Systemic-to-pulmonary artery surgical shunting, however, is still often performed with palliative intent in duct-dependent patients in the postnatal period and early infancy. Such surgical interventions at the early stages of life still represent an important cause of mortality and morbidity [1]. The placement of a stent for patent ductus arteriosus (PDA) by the percutaneous approach is an alternative to surgical palliation; it has attracted interest because of the absence of risks of phrenic or vagal paralysis, chylothorax, surgical adhesions, pulmonary branch distortion, shunt occlusion or stenosis, dissociated development of the right and left pulmonary arteries, pulmonary hypertension and per-operatory risk [2, 3]. In the developing countries, because of the limited number of centres which perform percutaneous PDA stenting and few patients, therefore, there is limited data about whether percutaneous PDA stenting approach could be the alternative to conventional surgical treatment [4, 5]. The aim of this study is to evaluate the early and mid-term results of percutaneous PDA stent placement in one centre from a developing country, Turkey.

PATIENT SELECTION AND METHODS

Thirteen patients who had had a PDA stent placed percutaneously between April 2010 and June 2011 were included in the study. Two patients had pulmonary atresia (PA) with ventricular septal defect (VSD), six a PA with intact ventricular septum (IVS), four a critical pulmonary stenosis (CPS) and one a PA with single ventricle physiology (complete atrio-ventricular septal defect-PA). The four patients with IVS-PA were also subjected to valve perforation by radiofrequency (RF). Before the intervention, all patients were diagnosed by standard echocardiography, their PDA anatomy was examined in detail and prostaglandin E₁ (PGE_l) treatment was started. If the PDA has a vertical or very tortuose shape which would prevent implantation via percutaneous stenting we preferred surgery. An informed consent form was signed by the parents before the transcatheter intervention.

HEART CATHETERIZATION AND STENT PLACEMENT

Eleven patients were operated under general anaesthesia and two under deep sedation. PGE_l infusion was interrupted prior to catheterization. The timing of this interruption differed among patients according to the tolerance to the absence of PGE_l. PDA anatomy was characterized through angiography of the aorta. Ductus length, largest and smallest diameters and point of origin were recorded. PDA was vertical and a little tortuose in two patients. Other cases had a PDA which arose from distal of the left subclavien artery and took a straight course. Access was venous in one patient and retrograde through the femoral artery in 12 others. After passing the duct with a 4F right or left Judkins catheter over a 0.18 hydrophilic guide wire, a 0.014 floppy coronary guide was inserted through the PDA and left in the right or left pulmonary artery. The width of the stent was estimated according to the body weight, the smallest ductal diameter and the diameter and distribution of the pulmonary artery. Pre-mounted stents for coronary arteries (Abbot Vascular, Santa Clara, CA, USA) were used in all patients. Three of the patients received two stents each. In the first patient, following the installation of a 3.5 × 9 mm stent, the embolization of the stent in the right pulmonary artery was observed while pulling back the guide wire. A second stent measuring 4.5 × 12 mm was then placed. In the second patient, after placing a 3.5 × 12 mm stent the fact that it did not completely cover the aortic side of the PDA was observed, and that was corrected by placing a second, 3.5 × 9 mm stent. As for the third patient, a first 3.5 × 15 mm stent was placed and observed not to cover the pulmonary side entirely. A second, 4 × 10 mm stent was then placed for correction. In four patients with PA-IVS, RF perforation was performed as the atretic area was membranous. The valve perforation was successful on the second attempt in the first patient. Both operations were carried out by pre-dilation with a coronary balloon catheter, then pulmonary valvuloplasty with a Tyshak balloon. As for the two other patients, RF perforation was unsuccessful on two attempts for each.

FOLLOW-UP PROTOCOL

All patients were heparinized for 24 h, after the intervention, after which they received aspirin. All patients received aspirin until surgery. Following stent placement, patients were evaluated by clinical examination, chest X-ray, echocardiography and electrocardiography. Daily echocardiographic examination was done during hospitalization. Stent position and patency were reassessed by echocardiography after 1 week of discharge and monthly until surgery. No patient had a fall in oxygen saturation (SatO₂) due to re-stenosis, and no re-catheterization or stent re-dilatation was performed due to such an occurrence. Catheterization was scheduled before palliative or total curative surgery if needed.

RESULTS

Patients

The characteristics of 13 patients with cyanotic congenital heart disease and duct-dependent pulmonary circulation who underwent a stent implantation between April 2010 and June 2011 are summarized in Table 1. Ductal length was 7.5–15 mm (average 11.2) and the narrowest ductal diameter was 2.7–4.2 mm (average 3.5). Non-confluent pulmonary arteries or aortopulmonary collaterals were not observed in any patient. One patient had a bilateral PDA. Accompanying cardiac and extra-cardiac abnormalities of patients are also shown in Table 1. Resting SatO₂ values after stent placement were between 70 and 90%. No patient needed re-intervention because of ductal stent stenosis. Reasonable pulmonary artery growth was achieved in all patients who planned to undergo surgery.

Acute phase follow-up

Catheterization

Single stent implantation was successfully performed in 10 patients and more than one in three patients. Average age (±SD) was 10.5 ± 5.7 days and body weight 3.1 ± 0.4 kg. The intervention duration was 138.88 ± 67.11 min, the duration of X-ray exposure 40.32 ± 25.86 min, that of intensive care unit stay 4.88 ± 6.07 days, hospital stay was 11.00 ± 6.89 days and the total follow-up period 86.4 ± 73.21 days. The amount of irradiation was 1054.27 ± 1106.91 cGy/m². The length of procedure time and irradiation dose was related to pulmonary valve perforation procedure. SatO₂ increased from 64.44 ± 5.83% to a post-intervention value of 81.88 ± 6.95%. Two procedure-related deaths were observed. The causes were characterized as pulmonary haemorrhage in one and retroperitoneal haemorrhage in the other case. The cause of pulmonary haemorrhage could not be explained. The patient with retroperitoneal haemorrhage had a very long activated clotting time (above 1000 s) despite appropriate heparinization; so the haemorrhage could not successfully stopped from the femoral arterial access site. Stent sizes and models are listed in Table 1. Transcatheter valvulotomy was performed in four cases, two of which were unsuccessful. Coronary circulation dependent on the right ventricle was not identified in any of the five patients with PA-IVS.

Complications related to the intervention

One patient underwent the implantation of a second stent after the first one had been embolized in the right pulmonary artery; this patient later died of retroperitoneal bleeding. Another patient had a first 3.5 × 12 mm stent placed, followed by another one of 3.5 × 9 mm. This patient was lost to a pulmonary haemorrhage during post-operative follow-up. The patient with retroperitoneal haemorrhage could be related to femoral arterial access.

Mid-term clinical outcome

Two patients died after discharge because of sepsis and aspiration pneumonia. Four patients underwent bidirectional cava pulmonary anastomosis at about 6 months of age. A Kawashima operation was done on the patient who had left atrial isomerism at 7.5 months of age. In all patients stents were easily taken out without any severe technical complication. Pulmonary artery reconstruction was required only in one patient. Three patients with IVS-PA or CPS have been followed up with biventricular physiology and one is patient still waiting for one and a half ventricle repair. One patient who was implanted for PDA stenting 4 months ago is still waiting for a Glenn operation for 4 months. Eight of 13 patients achieved stent patency during 6 months of follow up and re-stenosis develops in one patient (1/8; 12.5%) who had undergone Glenn operation at 4.5 months of age.

DISCUSSION

The implantation of stents for PDA appears to be an alternative to palliative or total repair surgery in patients with duct-dependent pulmonary circulation.

A ductal stent diameter of 4–5 mm can reduce the excess volumetric cardiac load, regulate the blood flow to the vascular bed and extend the pulmonary vascular bed. At the appropriate time for palliative or total repair surgery, the pulmonary artery measurements are evaluated by the Nakata and McGoon indexes [6, 7]. All of our patients who have been followed up six for months reached appropriate McGoon indexes for bidirectional cava pulmonary anastomosis. PDA stenting offer pulmonary artery growth which achieves more additional time for univentricular repair. On the other hand, we could not make any comments about the patients with hypoplastic pulmonary arteries especially patients with VSD-PA and heterotaxy syndrome [8]. In this regard those patients may need longer time to surgical repair. Therefore, re-stenosis of PDA stenting could be more problematic in this group of patients. Distortion of the branch pulmonary arteries, which is a disadvantage of aortopulmonary shunting by comparison with stent placement, has not been observed in our patients either. The development of new stents and the possibility of leaving long sheaths in place after passing through the PDA reduce the risk of stent embolization, perforation and acute constriction. Of particular importance is the covering of the entire length of the duct by the duct in patients whose pulmonary vascular bed is not fed from any other origin. In only three of our cases two separate stents were placed because of insufficient coverage by the first one. Rosenthal et al. [9] have reported low thrombosis and re-stenosis rates of the aortic end in patients with stent implantation in PDA.

In animal studies, re-stenosis ranging from light to severe importance is seen, as well as a re-stenosis rate over 75% after 6 months post-intervention. The use of coated stents able to impair endothelial proliferation has not yet been reported in this application. Re-dilatation, however, has been successfully performed in cases of stent re-stenosis [9, 10]. In the present study only one patient underwent early surgical repair due to re-stenosis. The mean follow-up duration in our patients was not so long. Therefore, this might be the main cause of why we did not encounter with re-stenosis and re-intervention requirement.

It is well known that passing a catheter again through the stent is technically very difficult and increases the risk of thrombosis and haemodynamic destabilization when compared with the primary intervention. The lack of coverage by the stent of the total length of the PDA causes re-intervention in most cases. None of our cases underwent re-intervention due to insufficient coverage of the entire ductal length. But we needed a second stent placement in two patients because of very long PDA course at the same session. It is hypothesized that the use of coated stent will reduce intraluminal endothelial cell proliferation, even though sufficient data are not available [11].

The patency period needed for a PDA in cases with obstruction and lesions of the pulmonary valve is variable. PDA patency is needed for only a short time in PA-IVS patients after a successful balloon valvuloplasty, because pulmonary circulation and left-to-right atrial shunting increases, followed by right ventricle recanalization. If cyanosis is to continue after the pulmonary valve perforation, stent placement in the PDA is indicated for these patients [6, 12]. Stent placement in the PDA was performed in two of our cases due to continuing cyanosis even after pulmonary valvulotomy by RF perforation. One of our patients, who underwent RF perforation and stent placement in the PDA, is being followed up with pulmonary stenosis and biventricular physiology. One patient with PA-IVS and two with CPS are being followed up with univentricular physiology. A higher morbidity and mortality rate was reported in the surgical valvotomy and Blalock–Taussig shunt when compared with transcatheter valve perforation and PDA stenting [6, 13].

As a small case number and relatively short follow-up period are the main limitation of this study. Studies with larger series, including various type of congenital heart disease and documentation of long-term outcomes are needed for showing the efficacy of percutaneous stenting of PDA.

In conclusion, to date early and late mortality and morbidity are still high in surgical shunt repair. However, the placement of a ductal stent has results comparable with those of palliative or reparative surgery, without sharing the risks of thoracotomy surgery. The implantation of a ductal stent can buy time before surgical treatment by allowing the development of the pulmonary arteries in patients. Vascular complications, stent re-stenosis and poor long-term pulmonary vascular growth in patients with very hypoplastic pulmonary arteries are the main possible concerns about mid-term results of the procedure. Therefore, in newborns with duct-dependent pulmonary circulation, the placement of a PDA stent by the percutaneous approach is a good alternative to surgery as a first palliative step; its long-term results remain to be evaluated.

Conflict of interest: none declared.

REFERENCES