Percutaneous Stent Placement in Children Weighing Less Than 10 Kilograms

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1 Pediatr Cardiol (2008) 29: DOI /s ORIGINAL ARTICLE Percutaneous Stent Placement in Children Weighing Less Than 10 Kilograms Ravi Ashwath Æ Daniel Gruenstein Æ Ernest Siwik Received: 29 July 2007 / Accepted: 21 October 2007 / Published online: 29 November 2007 Ó Springer Science+Business Media, LLC 2007 Abstract The objectives of this study were to evaluate the safety, efficacy, and outcomes of palliative percutaneous stent placement in infants with congenital heart disease (CHD). There is interest in improving outcomes of infants with CHD through interventional/surgical collaboration. Small, high-risk patients may benefit from delayed open operations, and endovascular stents may provide a means to defer surgery to more advantageous times in select infants. Patients weighing B10 kg in whom stent placement was attempted during were identified. Diagnoses, indications, angiographic and hemodynamic data, complications, and outcomes were reviewed. Seventeen stents were successfully placed in 15 patients. The mean age was months; the mean weight was 6.08 kg. Indications were branch pulmonary artery stenosis, coarctation, total anomalous pulmonary venous return with obstructed venous egress, right ventricle-pulmonary artery conduit, and shunt stenosis. Premounted Palmaz Genesis and Driver Mx stents were used. Average vessel diameter increased from 3.65 to 6.72 mm (p \ 0.001). The pressure gradient fell from 24 to 15 mm Hg (p \ 0.01). Two stents migrated. One was recaptured and implanted at the target site and one implanted away from the target site. None needed surgical intervention. Mean follow-up was 270 days. Five patients have had additional surgery; seven patients underwent 10 additional stent dilations. There was no procedural-related mortality. Five patients (33%) died R. Ashwath (&) E. Siwik Pediatric Cardiology, RB&C, Case Western Reserve University, Euclid Avenue, Cleveland, OH 44145, USA ravichandra_ashwath@yahoo.com D. Gruenstein Division of Pediatric Cardiology, University of Minnesota Children s Hospital, Fairview, Minneapolis, MN 55454, USA during the follow-up period, none attributable to the stent placement. We conclude that stent placement can be successfully accomplished in select, small, high-risk patients. A collaborative interventional/surgical paradigm is important to ensure that the risk-benefit ratio is properly evaluated during the patient selection. Keywords Infants Cardiac catheterization Congenital heart disease Intravascular stents have been used as both palliative and definitive therapy in patients with congenital heart disease (CHD). However, until recently, stent placement has generally been avoided in infants and small children due to the large delivery systems and balloon catheters required to place the stents. The introduction of lower-profile and premounted stent-balloon systems has made stent delivery in infants a more feasible option. However, the use of stents in small children is still hampered by need for serial dilatations and/or surgery to be able to ultimately achieve adequate vascular diameters commensurate with somatic size. Despite these caveats, many centers feel that selective stent placement in infants may be an appropriate palliation because of prohibitive surgical risk and/or associated comorbid conditions. We report our experience with intravascular stent implantation in patients weighing \10 kg. Materials and Methods A retrospective review was performed of patients who went to the cardiac catheterization laboratory at Rainbow Babies & Children s Hospital between March 2003 and November

2 Pediatr Cardiol (2008) 29: to identify patients weighing B10 kg in whom percutaneous stent implantation was attempted. We identified the underlying congenital heart lesion, comorbid conditions, anatomic site of stent implantation, hemodynamic and angiographic outcomes, fluoroscopic time, and procedural complications. Follow-up data were collected, with end points for follow-up being return for further catheterization, operative intervention, and death. Data are reported as the mean increase in diameter of the lumen and reduction in gradients pre and post stent placement. A p value \0.05 was considered statistically significant. Results Patient Data Between March 2003 and November 2006, 15 patients were identified in whom percutaneous intravascular stent placement was attempted. A total of 17 stents were placed in the 15 patients identified. The mean age was months (range, months). The mean weight was 6.08 kg (range, kg). Vascular route of stent implantation included femoral vein (n = 9), femoral artery (n = 3), internal jugular (n = 2), and transhepatic (n = 1). The underlying heart lesions were varied, as were the indications for stent implantation (Table 1). The most common target site for stent implantation was the proximal branch pulmonary arteries (n = 10; 58.8 %) Other target lesions included the aortic arch (n = 2; 11.8%), right ventricle-pulmonary artery (RV-PA) conduit (n = 2; 11.8%), modified Blalock-Taussig (mbt) shunt (n = 1; 5.9%), and obstructed vertical vein (n = 1; 5.9%), which was reported separately earlier [11] (Figs. 1 4). Comorbid conditions were identified (Table 1) and included. Procedural Data All procedures were performed under general anesthesia. The average fluoroscopy time was 43 min (range, min). Premounted Palmaz-Genesis stents (Cordis, Johnson and Johnson, Miami, FL) were successfully implanted in 16 target sites. One Driver Mx stent (Medtronic; Fridley, MN) was used to stent the BT shunt. All 15 patients had angiographic improvement after the stents were placed. The average vessel diameter increased from 3.65 mm (range, mm) prestent to 6.72 mm (range, mm) poststent (p \ 0.001). This constituted an overall increase in vessel diameter of % (range, 26% 325%). A poststent gradient was recorded in nine patients. The gradients were reduced from a prestent mean of 31.5 mm Hg (range, mm Hg) to a poststent mean of 15.9 mm Hg (range, 0 45 mm Hg; p \ 0.01). This constituted an overall gradient reduction of 50.4% (range, 9.6% 100). The data are further summarized in Table 1. Complications There were two technical/procedural complications related to stent placement. A coronary stent was stripped off the balloon by a sheath tip when trying to enter an obstructed mbt shunt. We were unable to recapture the balloon within the shunt, so the guide wire was repositioned in the right axillary artery and the stent was recaptured and deployed there. In a second patient, undergoing left pulmonary artery (LPA) stent placement from an internal jugular approach, a partially deployed stent embolized to the distal LPA. This was successfully recaptured and deployed appropriately in the LPA. There were no arrhythmias requiring intervention, procedural transfusions given, or vascular complications during, or as a result of, the stenting procedures. Follow-up At follow-up, four patients have stents in place, with an average follow-up period of days (range, days). Six patients had their stents removed at their subsequent surgical intervention, with a mean time interval of 208 days (range, days). There were no complications due to the stents in follow-up surgeries. They were either left in situ or cut through and patched with GORE- TEX (W. L. Gore and associates, Newark, DE) if needing enlargement. Seven patients (46.7%) returned to the catheterization lab for further stent dilations, which included six LPA, three right pulmonary artery, and one coarctation of the aorta dilations. Six patients (40%) went to the operating room for further intervention. Five of these children had their stents removed at the time of surgical intervention. Two stents were left in situ during surgery. One was left in the LPA to be removed at a subsequent homograft interposition. One patient, with hypoplastic left heart syndrome, had a stent placed in her Sano shunt due to cyanosis and shunt stenosis. The stent was left in situ at the time of the bidirectional Glenn after preoperative angiography had demonstrated progressive intimal narrowing in the stent. Deaths at Follow-up Five patients (33.3%) have died since the stenting procedure was performed. The mean time of death was 93.5 days after the stent was placed (range, days).

3 564 Pediatr Cardiol (2008) 29: Table 1 Diagnosis, indications, stent target site, weight, and comorbidities of our patient population Patient No. Congenital disease heart Indication(s) Weight (kg) Age at placement (mo) Associated comorbidity(ies) Comment(s) 1 Truncus arteriosus RPA stenosis DiGeorge syndrome Alive, well S/P complete repair 2 TOF, pulmonary atresia, S/P MRBTS, S/P homograft, LPA stenosis LPA stenosis RPA stenosis Alive; had stent dilations twice 3 TAPVR, vertical vein Vertical vein stenosis VA ECMO Alive, well S/P complete repair 4 Tricuspid atresia, rhabdomyoma, aortic arch obstruction 5 Pulmonary atresia/ Ventricular septal defect 6 Truncus arteriosus II, S/P repair 7 PA/VSD S/P RVOT patch and branch PA stenosis 8 TOF, APV, S/P RV- PA conduit 9 TOF, pulmonary atresia, MAPCA 10 Elastin arteriopathy, BPAS, SVAS 11 IAA, S/P DKS and 4- mm BT shunt 12 IAA, S/P DKS and 4- mm BT shunt, S/P Rastelli 13 AVSD, COA, S/P patch augmentation of hypoplastic aorta 14 Truncus arteriosus, S/ P RV-PA conduit 15 HLHS, S/P Norwood with Sano shunt COA Atrial rhabdomyomas Expired 14 mo later due to respiratory failure LPA stenosis None Alive; returned to Saudi Arabia RPA stenosis 6 7 Tracheomalacia with tracheostomy Alive; has had stent dilations LPA stenosis q11 deletion FUO; expired 9 mo post stent placement RV-PA homograft stenosis Developmental delay; hip dislocations Alive; has had conduit replacement with stent removal LLLPA stenosis DiGeorge syndrome Alive with stents in place LPA and RPA stenosis Elastin arteriopathy Alive, well, S/P surgical repair with stents removed BT shunt narrowing None Alive, well, stent removed at surgery LPA and RPA stenosis Partial deletion of chr 22; on ECMO Aortic narrowing Laryngotracheomalacia, tracheostomy, sepsis RV-PA homograft stenosis Expired 1 day post stent placement due to severe RV dysfunction Expired 2 wk post stent placement secondary to respiratory failure, sepsis DiGeorge syndrome Alive, well; stent removed at homograft revision surgery Sano shunt narrowing None Alive and well Note. APV, absent pulmonary valve; AVSD, atrioventricular septal defect; BPAS, bilateral pulmonary artery stenosis; COA, coarctation of the aorta; DKS, Damus-Kaye-Stansel; ECMO, extracorporeal membrane oxygenator; HLHS, hypoplastic left heart syndrome; IAA, interrupted aortic arch; LPA, left pulmonary artery; LLLPA, left lower lobe pulmonary artery; MAPCA, multiple aortopulmonary collaterals; MRBTS, modified right Blalock-Taussig shunt; PA, pulmonary artery; RPA, right pulmonary artery; RV, right ventricle; RVOT, right ventricular outflow tract; S/P, status post; SVAS, supravalvar aortic stenosis; TAPVR, total anomalous pulmonary venous return; TOF, tetralogy of Fallot; VSD, ventricular septal defect None of the deaths were directly attributed to the catheterization procedure or to the presence of the intravascular stent. The clinical histories of the infants that died are detailed further below. Patient 1 had repaired truncus arteriosus, DiGeorge syndrome, and right pulmonary artery stent. She died of autopsy-confirmed septicemia and intusseception 1.5 years following stent placement. Patient 4 had tricuspid atresia, tuberous sclerosis, and multiple, large intracardiac rhabdomyomas with distal arch hypoplasia/mild coarctation. She was initially palliated with a pulmonary artery band. Her arch was palliated nonsurgically because of concerns about her neurologic status and underlying comorbid conditions. She died of respiratory failure 13 months after aortic stent placement and 2 months after bidirectional Glenn.

4 Pediatr Cardiol (2008) 29: Fig. 1 Pulmonary artery stents. A Prestent: diffuse narrowing of both the right and the left branch pulmonary arteries is seen (arrows). B Poststent: there is a significant increase in the diameters of the pulmonary arteries at the sites of the implanted stents (arrows) Fig. 2 Aorta stent. A Prestent: diffuse narrowing of the distal aortic arch and proximal descending aorta is seen (arrows). LSC, left subclavian artery; ARS, anomalous right subclavian artery. B Poststent: there is a significant increase in the diameter of the aorta at the site of the stent implantation (arrows), with maintenance of flow through the subclavian arteries Patient 7 had an LPA stent placed following correction of pulmonary atresia/ventricular septal defect. She had associated DiGeorge syndrome. She developed persistent fevers of unknown origin for several months and died 9 months after stent placement. This patient had undergone extensive evaluation for her fevers and no clear infectious etiology was ever established. Patient 12 had an interrupted aortic arch and severe subaortic obstruction. He was initially palliated with a Damus- Kaye-Stansel procedure, with subsequent RV-PA conduit/ ventricular septal defect closure. He had severe RV dysfunction and low cardiac output syndrome. He had been placed on an extracorporeal membrane oxygenator and there was concern about residual pulmonary artery stenosis. While on mechanical support, he underwent bilateral PA stent placement in an attempt to further unload his right ventricle. This patient died of multiorgan failure 1 day after the procedure following withdrawal of mechanical support. Patient 13 was diagnosed at birth with partial atrioventricular septal defect with coarctation of the aorta. She underwent initial coarctation repair, then underwent stent placement for residual coarctation. She had severe laryngotracheomalacia, underwent tracheostomy, and subsequently died secondary to respiratory failure and E. coli septicemia. Discussion Vascular stenosis in patients with CHDs can be the cause of significant morbidity and mortality [1, 6, 10]. Intravascular stent placement for the treatment of obstruction in CHD was first introduced by Mullins et al. in 1988 [14]. Since then stents have been used to treat pulmonary artery and systemic venous obstruction [15 17] and, more recently, systemic arterial obstructions [2, 8, 12]. The hemodynamic benefits have been reported previously, including recently in younger children with right heart obstruction [15, 14, 19]. They are also gaining further use in systemic arterial obstruction and in hybrid palliation of hypoplastic left heart syndrome and

5 566 Pediatr Cardiol (2008) 29: Fig. 3 Right ventricle (RV)- pulmonary artery (PA) conduit stent. A Prestent: lateral projection shows narrowing of the RV-PA conduit (arrow). MPA, main pulmonary artery. B Poststent: there is a significant increase in the diameter of the conduit at the site of stent implantation (arrow) other CHDs [4]. The limiting factor for the use of stents in infants historically has been the rigidity of the stents and the sheath size required for delivery. However, this technical issue has become less problematic with the availability of low-profile flexible stents and balloons. Hence implantation rates have increased [9]. The deliverability of the Genesis stent has been described by Forbes et al. [3], and in our series the majority of the stents were premounted Genesis stents. Premounted Genesis stents, although more limited than unmounted Genesis XD stents in their achievable final diameter, were chosen because of the ease of their deliverability and the understanding that these stents would be amenable to removal at subsequent surgical interventions. Genesis stent 19/29/39 has the ability to be dilated from 5 to 20 mm in diameter. Stent implantation will result in a fixed vessel diameter, preventing enlargement of the vessel as the child grows. Re-expansion of the stent series can be performed years later, eventually reaching diameters appropriate for adult-size patients. The reasons and indications for stent placement over balloon dilations were varied but not limited to the fact that balloon dilations alone failed to achieve the expected results during the procedure, stents being placed in venous structures, feasibility of future dilations with stents, and better short-term and long-term outcomes with stents than with balloon dilations alone. This study of exclusively small children further supports that percutaneous intervention is a feasible and safe treatment option in selected small infants. Our population included a diverse patient mix, with venous, arterial, shunt, and conduit stenoses, and included critically ill patients on mechanical support. These infants were felt to be at a prohibitively high risk for immediate surgical intervention, or felt to be better served by catheter-based palliation because of important comorbid conditions. The long-term mortality rate of 33% in this population is of note in that regard and raises the question whether this may reflect the inferiority of catheter-based intervention to a traditional surgical approach. Although such a contention is impossible to disprove, it should be noted that all patients underwent percutaneous intervention after initial consideration of surgery and that, by and large, these interventions were successful in achieving desired Fig. 4 Stent placement in a modified Blalock-Taussig shunt (mbts). A Prestent: a coronary catheter placed retrograde through the aorta and into the shunt off the base of the innomonate artery shows significant shunt occlusion (arrow), with minimal contrast crossing into the pulmonary arteries. B Poststent: there was immediate improvement in the diameter of the shunt at the site of stent placement (large arrow). A residual narrowing was seen in the proximal shunt (small arrow). LPA, left pulmonary artery; RP, right pulmonary artery

6 Pediatr Cardiol (2008) 29: hemodynamic results. Moreover, with the exception of the one patient who underwent intervention in the immediate postoperative period, all the deaths in this series were remote (average, 10.1 months) from the procedure itself and related to other important comorbidities. This further lends support to the notion that mortality data primarily reflect the risk profile of the patient group and not of the therapeutic approach chosen. It is interesting that two patients died of infectious complications during the followup period, both of whom had associated DiGeorge syndrome. Despite a high degree of concern regarding the presence of an intravascular foreign body in these patients, we were unable to establish bacteriologic or imaging evidence that the stent itself was a contributing factor, and the temporal relationship to the illnesses was at a time when the stents would be expected to have established mature endothelial coverage. [15] Study Limitations The study is primarily limited by its retrospective nature, small sample size, and lack of a true control group with regard to long-term outcomes. Although the study population had diverse cardiac pathologies, the focus of the study was to review the technical and clinical outcomes in young, small infants, and not individual diagnoses per se. The follow-up period was limited in some patients. Even though the procedure is successful, it is not possible to achieve satisfying results in all patients. Conclusions Percutaneous stent placement is safe and can provide successful palliation in select small, high-risk patients across a wide range of pathologies. There appears to be little morbidity/mortality associated with the procedure in the short- to midterm follow-up period that we used. A collaborative interventional/surgical paradigm remains important to ensure that the risk-benefit ratio is appropriate for desired short- and long-term outcomes. References 1. 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