Endovascular Stent Placement for Right Ventricle to Pulmonary Artery Conduit Stenosis in the Norwood with Sano Modification

Pulmonary Flow Management by Combination Therapy of Hemostatic Clipping and Balloon Angioplasty for Right Ventricular-Pulmonary Artery Shunt in Hypoplastic Left Heart Syndrome

Controlling pulmonary blood flow in patients who have undergone Norwood palliation, especially early postoperatively, is challenging due to a change in the balance of systemic and pulmonary vascular resistance. We applied a combination therapy of clipping and balloon angioplasty for right ventricle-pulmonary artery (RV-PA) shunt to control pulmonary blood flow, but the influence of the combination therapy on the PA condition is uncertain. Retrospectively analysis was conducted of all infants with hypoplastic left heart syndrome who had undergone Norwood palliation with RV-PA shunt at Okayama University Hospital from January 2008 to September 2022. A total of 50 consecutive patients underwent Norwood palliation with RV-PA shunt in this study period. Of them, 29 patients underwent RV-PA shunt flow clipping, and the remaining 21 had unclipped RV-PA shunt. Twenty-three patients underwent balloon angioplasty for RV-PA shunt with clips. After balloon angioplasty, oxygen saturation significantly increased from 69 (59-76)% to 80 (72-86)% (p < 0.001), and the narrowest portion of the clipped conduit significantly improved from 2.8 (1.8-3.4) to 3.8 (2.9-4.6) mm (p < 0.001). In cardiac catheterizations prior to Bidirectional cavo-pulmonary shunt (BCPS), there were no significant differences in pulmonary-to-systemic flow ratio (Qp/Qs), ventricular end-diastolic pressure, Nakata index, arterial saturation, mean pulmonary artery pressure and pulmonary vascular resistance index. On the other hand, in Cardiac catheterizations prior to Fontan, Nakata index was larger in the clipped group (p = 0.02). There was no statistically significant difference in the 5-year survival between the two groups (clipped group 96%, unclipped group 74%, log-rank test: p = 0.13). At least, our combination therapy of clipping and balloon angioplasty for RV-PA shunt did not negatively impact PA growth. Although there is a trend toward better but not statistically significant difference in outcomes in the clipped group compared to the non-clipped group, this treatment strategy may play an important role in improving outcomes in hypoplastic left heart syndrome.

Mathematical Analysis and Physical Profile of Blalock-Taussig Shunt and Sano Modification Procedure in Hypoplastic Left Heart Syndrome: Review of the Literature and Implications for the Anesthesiologist

The first stage of surgical treatment for hypoplastic left heart syndrome (HLHS) includes the creation of artificial systemic-to-pulmonary connections to provide pulmonary blood flow. The modified Blalock-Taussig (mBT) shunt has been the technique of choice for this procedure; however, a right ventricle-pulmonary artery (RV-PA) shunt has been introduced into clinical practice with encouraging but still conflicting outcomes when compared with the mBT shunt. The aim of this study is to explore mathematical modeling as a tool for describing physical profiles that could assist the surgical team in predicting complications related to stenosis and malfunction of grafts in an attempt to find correlations with clinical outcomes from clinical studies that compared both surgical techniques and to assist the anesthesiologist in making decisions to manage patients with this complex cardiac anatomy. Mathematical modeling to display the physical characteristics of the chosen surgical shunt is a valuable tool to predict flow patterns, shear stress, and rate distribution as well as energetic performance at the graft level and relative to ventricular efficiency. Such predictions will enable the surgical team to refine the technique so that hemodynamic complications be anticipated and prevented, and are also important for perioperative management by the anesthesia team.

A 10-year single-centre experience in percutaneous interventions for multi-stage treatment of hypoplastic left heart syndrome

OBJECTIVES

The purpose of this paper is to report our 10 years of experience of interventional treatment of patients with hypoplastic left heart syndrome and to focus on the frequency, type, and results of percutaneous interventions during all the stages of palliation, considering the different techniques, devices, and complications.

BACKGROUND

Constant progress in surgical treatment of congenital heart defects in the last decade has significantly improved the prognosis for children with hypoplastic left heart syndrome. However, morbidity and mortality remain relatively high. Modern interventional procedures complement or occasionally replace surgical treatment.

METHODS

Between January, 2001 and December, 2010, 161 percutaneous interventions were performed in 88 patients with hypoplastic left heart syndrome. Patients were divided into four groups: (a) before the first surgical treatment including hybrid approach, (b) after first-stage Norwood operation, (c) after second-stage bidirectional Glenn operation, and (d) after third-stage Fontan operation.

RESULTS

Percutaneous interventions resulted in statistically significant changes in pulmonary artery pressures, vessel diameters, and O2 saturation. Complications occurred in 4.3% of interventions and were related mainly to stent implantation in stenosed pulmonary arteries.

CONCLUSIONS

Percutaneous interventions may result in haemodynamic stability and reduction in the number of operations. They may result in significant changes in pulmonary artery pressures, vessel diameters, O2 saturation, with a low rate of complications, which are mainly related to stent implantation in the pulmonary arteries.

Incidence of and risk factors for catheterization-induced complete heart block in the pediatric cardiac catheterization laboratory

BACKGROUND

The majority of the literature on catheterization-induced heart block (CIHB) was published >30 years ago. The field of cardiac catheterization has evolved, performing more interventional compared with diagnostic cases. We sought to determine the incidence and risk factors of CIHB.

METHODS AND RESULTS

A catheterization database that records the occurrence of adverse events on all cases was queried for heart block. Additional retrospective data on event outcome were collected on patients who developed CIHB. Multivariable logistic regression modeling was used to identify risk factors of CIHB (odds ratio, 95% confidence interval). In a 6-year period, 6183 cases were performed. The median weight was 15.0 (7.0-47.0) kg, with 29% consisting of infants <1 year. A total of 72% involved complex congenital heart disease. One hundred thirty-five cases were complicated by CIHB (2.2%; 95% confidence interval, 1.9-2.6). Age <1 year (3.0; 2.2-4.3) and case duration ≥2 hours (3.4; 2.0-6.0) were risk factors of CIHB; cardiac anatomy and intervention performed were not. A total of 96% of CIHB recovered within 1 week but 6 patients underwent pacemaker placement (3 L-loop ventricles, 2 intracardiac devices, 1 double inlet-double outlet RV). Of these, 50% recovered atrioventricular nodal conduction within 1 month; 2 patients with L-loop ventricles and 1 patient with a left ventricular-to-right atrial device did not recover.

CONCLUSIONS

The incidence of CIHB in the pediatric cardiac catheterization laboratory is low at 2.2%. Risk factors include young age and long case duration. The recovery of atrioventricular nodal function after CIHB is high and follows a similar time course to that of postsurgical heart block.

Treatment of right ventricle to pulmonary artery conduit stenosis in infants with hypoplastic left heart syndrome

OBJECTIVES

To determine the incidence of right ventricle-to-pulmonary artery (RV-PA) conduit stenosis after the Norwood I operation in patients with hypoplastic left heart syndrome (HLHS), and to determine whether the treatment strategy of RV-PA conduit stenosis has an influence on interstage and overall survival.

METHODS

Ninety-six patients had a Norwood operation with RV-PA conduit between 2002 and 2011. Details of reoperations/interventions due to conduit obstruction prior to bidirectional superior cavopulmonary anastomosis (BSCPA) were collected.

RESULTS

Overall pre-BSCPA mortality was 17%, early mortality after Norwood, 6%. Early angiography was performed in 34 patients due to desaturation at a median of 8 days after the Norwood operation. Fifteen patients (16%) were diagnosed with RV-PA conduit stenosis that required treatment. The location of the conduit stenosis was significantly different in the patients with non-ringed (proximal) and the patients with ring-enforced conduit (distal), P = 0.004. In 6 patients, a surgical revision of the conduit was performed; 3 of them died prior to BSCPA. Another 6 patients had a stent implantation and 3 were treated with balloon dilatation followed by a BSCPA in the subsequent 2 weeks. All patients who were treated interventionally for RV-PA conduit obstruction had a successful BSCPA. Patients who received a surgical RV-PA conduit revision had a significantly higher interstage (P = 0.044) and overall mortality (P = 0.011) than those who received a stent or balloon dilatation of the stenosis followed by an early BSCPA.

CONCLUSIONS

RV-PA conduit obstruction after Norwood I procedure in patients with HLHS can be safely and effectively treated by stent implantation, balloon dilatation and early BSCPA. Surgical revision of the RV-PA conduit can be reserved for patients in whom an interventional approach fails, and an early BSCPA is not an option.

Interventions after Norwood procedure: comparison of Sano and modified Blalock-Taussig shunt

Improved results have evolved from the modified Norwood procedure (NP). This study compares the incidence of interventions after NP with the Sano (n = 37) and modified Blalock-Taussig (BT n = 70) shunt. Incidence, location, interval of interventions, and weight were retrospectively analysed for 107 neonates undergoing NP during the period from October 2002 to December 2009. Forty-six (43.0 %) patients underwent interventions, mostly for dilatation of the aortic arch ([DAA] n = 26 [24.3 %]; Sano n = 10, BT n = 16, p = 0.6), dilatation of the shunt ([DS] n = 15 [14.0 %]; Sano n = 11, BT n = 4; p = 0.002), or closure of aortopulmonary collaterals ([APC] n = 15 [14.0 %]; Sano n = 3, BT n = 12; p = 0.08). Mean interval after NP and body weight at DAA, DS, and APC were 72.4 ± 18.9, 108.5 ± 15.8, and 110.7 ± 17.8 days and 4.5 ± 1.3, 4.9 ± 1.9, 5.3 ± 1.2 kg, respectively. The interventions were not associated with mortality but with a greater rate of complications (9 of 46 [21.4 %]) compared with the rate after diagnostic catheterization (0 of 45, p = 0.03). Complications included closure of the femoral or subclavian artery (n = 5), cerebral embolic or bleeding events (n = 4), cardiopulmonary resuscitation (n = 3), and temporary heart block (n = 2). Actuarial survival was similar from the postoperative month 8 onward at 78.6 ± 4.9 % (95 % confidence interval [CI] 67.0-86.5 %) for Sano and 78.4 ± 6.8 % (95 % CI 61.4-88.6 %) for BT (p = 0.95). Interventions after NP were common irrespective of shunt type. However, a significantly greater rate of shunt interventions was noted in the Sano group. In particular, interventions addressing the aortic arch and the shunt were related with a significant rate of complications.

Usefulness of balloon angioplasty for the right ventricle-pulmonary artery shunt with the modified Norwood procedure

OBJECTIVE

We sought to evaluate the efficacy of balloon angioplasty (BA) for severely desaturated patients due to a stenotic right ventricle (RV) to pulmonary artery (PA) shunt following modified Norwood procedure.

METHODS

Of 87 patients who underwent a Norwood procedure with the RV-PA shunt between February 1998 through March 2010, 22 (25%) patients underwent BA. The efficacy of BA was assessed by angiographic measurement of the changes in the internal diameters of the stenotic portions of the shunt, changes in arterial saturation and clinical outcomes.

RESULTS

BA was performed for stenotic RV-PA shunts following stage I palliation (n = 17, 77%), or those placed as an additional blood source (n = 5, 23%, 3 patients awaiting biventricular repair, 2 patients following stage II palliation). The location of the BA was at the distal anastomosis in 12 (54.5%), proximal anastomosis in 21 (95.4%) and in the mid-portion of the shunt in 11 (50%) cases. The diameters of these three shunt portions were measured from the anterior-posterior and lateral angiographic images, increasing significantly after BA (p < 0.0001) in all. Arterial saturation significantly improved after BA in all cases (66.5 ± 4.3% to 79.4 ± 3.4%, p < 0.0001). Freedom from reintervention was 100%. All patients underwent subsequent elective planned surgery at an appropriate age with no mortality.

CONCLUSIONS

A BA-alone strategy for a stenotic RV-PA shunt was effective for all three shunt portions, minimizing shunt-related premature surgical intervention.

Effect of endovascular stenting of right ventricle to pulmonary artery conduit stenosis in infants with hypoplastic left heart syndrome on stage II outcomes

There is growing awareness that the Norwood procedure with the Sano modification is prone to early right ventricular to pulmonary artery (RV-PA) conduit stenosis resulting in systemic oxygen desaturation, increased interstage morbidity, and death. We report our experience with endovascular stent placement for conduit stenosis and compare the outcomes at stage II surgery between stented and nonstented infants. The medical records of all patients with hypoplastic left heart syndrome who received an RV-PA conduit at Norwood palliation from May 2005 to January 2010 were reviewed. The preoperative anatomy, demographics, operative variables, and outcomes pertaining to the Norwood and subsequent stage II surgeries were obtained and compared between stented and nonstented infants. The pre- and post-stent oxygen saturation, stenosis location, type and number of stents implanted, concomitant interventions, procedure-related complications, and reinterventions were collected. Of the 66 infants who underwent the Norwood procedure with RV-PA conduit modification, 16 (24%) received stents. The anatomy, demographics, and outcome variables after the Norwood procedure were similar between the stented and nonstented infants. The age at catheterization was 93 ± 48 days, and the weight was 4.9 ± 1.2 kg. The oxygen saturation increased from 66 ± 9% before intervention to 82 ± 6% immediately after stenting (p <0.0001). No interstage surgical shunt revisions were performed in either group. Age, weight, pre-stage II echocardiographic variables, oxygen saturation, and operative and outcome variables, including mortality, were similar between the 2 groups. In conclusion, endovascular stent placement for RV-PA conduit stenosis after the Norwood procedure leads to improved systemic oxygen levels and prevents early performance of stage II surgery without compromising stage II outcomes.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions

OBJECTIVE

To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original nominal diameter using stents.

METHODS

Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original nominal diameter of the shunts.

RESULTS

During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original nominal to final stented diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures.

CONCLUSION

In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond nominal diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure.

Acute interventions for stenosed right ventricle-pulmonary artery conduit following the right-sided modification of Norwood-Sano procedure

INTRODUCTION

The Norwood stage 1 procedure was modified by Sano with right ventricle-pulmonary artery (RV-PA) conduit replacing BT shunt. In our institution, this has been further modified by placing the conduit from the RV outflow tract to the right side of the neo-aorta.

PATIENTS AND METHODS

Between April 2002 and October 2008, 227 modified Norwood procedures were performed. Eighteen had the Sano modification with the conduit to the left of the neo-aorta whereas 209 had the right-sided modification, which is the study population. A total of 18 (8.6%) patients presented with cyanosis due to conduit stenosis with median age 4 months and median weight 6.3 kg.

RESULTS

Twelve patients underwent transcatheter stent placement in stenosed RV-PA conduit. A total of 16 coronary stents were implanted in 12 patients with 4 patients each receiving 2 stents. The mean saturations increased from 60% to 74%. There was one late mortality which was non-procedure related. Five patients treated with surgical take down of the RV-PA conduit and creation of a cavo-pulmonary shunt, whilst one patient had replacement of RV-PA conduit. There were no early postoperative deaths. The mean saturations improved from 54% to 75%.

CONCLUSIONS

The RV-PA conduit stenosis is a life-threatening complication after the modified Norwood Stage I procedure. This may require urgent surgery to replace the conduit or to perform a cavo-pulmonary shunt but as an alternative, transcatheter stent placement can be used with equal effectiveness and with a low risk of complications. The catheter approach is less invasive and the results show that it is an excellent option to relieve the stenosis even in the right-sided RV-PA conduit.