Catheter interventional treatment of Sano shunt obstruction in patients following modified Norwood palliation for hypoplastic left heart syndrome

Use of the novel curved GOKU balloon catheter for acute-angled lesions in palliative surgery for congenital heart disease: comparison with a conventional straight balloon

Obstruction develops commonly at the acute-angled portion of the vessels following palliative surgery, such as systemic-pulmonary shunt (SP shunt), right ventricle-to-pulmonary artery shunt (RV-PA shunt) in the Norwood-Sano procedure for hypoplastic left heart syndrome, and cavopulmonary (Glenn) anastomosis. Although balloon angioplasty is a treatment option, dilation with existing straight balloons is sometimes ineffective and technically complicated because of balloon slippage and target vessel distortion. In this study, we investigated the effectiveness of a curved GOKU balloon catheter for balloon angioplasty in postoperative acute-angled lesions associated with palliative surgery for congenital heart disease. We reviewed patients who underwent balloon angioplasty for angled lesions complicated by SP shunt, RV-PA shunt, or Glenn anastomosis, using the novel curved GOKU or a conventional balloon catheter, such as a Sterling balloon catheter. We evaluated patients' backgrounds, balloon specifications, target lesion anatomical features and angles, and short-term outcomes. We evaluated 45 procedures in 18 patients. A curved GOKU was used in 20 procedures, and a Sterling balloon in 25 procedures. The angulation of the lesions at maximum balloon inflation was significantly smaller using a curved GOKU vs a Sterling balloon [70-120 (mean ± standard deviation, 97 ± 40) degrees vs 110-180 (149 ± 46) degrees, respectively; p < 0.001], while the original angle was similar between the groups. Patients' short-term outcomes with the curved GOKU were excellent, with a significantly better percent increase in minimum lumen diameter of 0-220% (92% ± 66%) vs 0-46% (18% ± 15%) with the Sterling balloon (p < 00.1) and with less frequent balloon slippage. The curved GOKU was more effective in balloon angioplasty for acute-angled lesions compared with a conventional straight balloon, likely because of better conformability to the lesion angle and slip resistance.

Design and numerical simulation for the development of an expandable paediatric heart valve

Current paediatric valve replacement options cannot compensate for somatic growth, leading to an obstruction of flow as the child outgrows the prosthesis. This often necessitates an increase in revision surgeries, leading to legacy issues into adulthood. An expandable valve concept was modelled with an inverse relationship between annulus size and height, to retain the leaflet geometry without requiring additional intervention. Parametric design modelling was used to define certain valve parameter aspect ratios in relation to the base radius, R_b, including commissural radius, R_c, valve height, H and coaptation height, x. Fluid-structure simulations were subsequently carried out using the Immersed Boundary method to radially compress down the fully expanded aortic valve whilst subjecting it to diastolic and systolic loading cycles. Leaflet radial displacements were analysed to determine if valve performance is likely to be compromised following compression. Work is ongoing to optimise valvular parameter design for the paediatric patient cohort.

Interstage evaluation of homograft-valved right ventricle to pulmonary artery conduits for palliation of hypoplastic left heart syndrome

OBJECTIVE

Palliation of hypoplastic left heart syndrome with a standard nonvalved right ventricle to pulmonary artery conduit results in an inefficient circulation in part due to diastolic regurgitation. A composite right ventricle pulmonary artery conduit with a homograft valve has a hypothetical advantage of reducing regurgitation, but may differ in the propensity for stenosis because of valve remodeling.

METHODS

This retrospective cohort study included 130 patients with hypoplastic left heart syndrome who underwent a modified stage 1 procedure with a right ventricle to pulmonary artery conduit from 2002 to 2015. A composite valved conduit (cryopreserved homograft valve anastomosed to a polytetrafluoroethylene tube) was placed in 100 patients (47 aortic, 32 pulmonary, 13 femoral/saphenous vein, 8 unknown), and a nonvalved conduit was used in 30 patients. Echocardiographic functional parameters were evaluated before and after stage 1 palliation and before the bidirectional Glenn procedure, and interstage interventions were assessed.

RESULTS

On competing risk analysis, survival over time was better in the valved conduit group (P = .040), but this difference was no longer significant after adjustment for surgical era. There was no significant difference between groups in the cumulative incidence of bidirectional Glenn completion (P = .15). Patients with a valved conduit underwent more interventions for conduit obstruction in the interstage period, but this difference did not reach significance (P = .16). There were no differences between groups in echocardiographic parameters of right ventricle function at baseline or pre-Glenn.

CONCLUSIONS

In this cohort of patients with hypoplastic left heart syndrome, inclusion of a valved right ventricle to pulmonary artery conduit was not associated with any difference in survival on adjusted analysis and did not confer an identifiable benefit on right ventricle function.

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.

Clinical course and interstage monitoring after the Norwood and hybrid procedures for hypoplastic left heart syndrome

Infants with hypoplastic left heart syndrome (HLHS) are at risk for interstage morbidity and mortality, especially between the first and second surgical stages after the Norwood and hybrid procedures. This study compared the morbidity and mortality of patients treated by either the Norwood or the hybrid procedure for HLHS between the first and second stages who were undergoing interstage monitoring. Between October 2008 and December 2011, 26 infants (14 boys) with HLHS (n = 16) and other univentricular heart malformations with aortic arch anomaly (n = 10) were scheduled for interstage monitoring after Norwood I (n = 12) and hybrid (n = 14) procedures. Three infants (11.5 %) died after first-stage palliation (one hybrid patient and two Norwood patients), and three infants (11.5 %) died after second-stage palliation (two hybrid patients and one Norwood patient) (p = 0.83), all after early second-stage surgery (<90 days). The Norwood I and hybrid procedures did not differ in terms of overall mortality (23 %) (three hybrid and three Norwood patients; p = 1.00). Seven infants (26.9 %) could not be discharged from the hospital due to hemodynamic instability and were referred for early second-stage surgery (<90 days). After the first stage, the invasive reevaluation rate before discharge was high (53.8 %), with cardiac catheterizations for 8 of 14 patients after the hybrid procedure and for 6 of 12 patients after the Norwood procedure (p = 0.69). A total of 11 reinterventions were performed (eight by catheter and three by surgery). Of the eight catheter reinterventions, five were performed for hybrid patients (p = 0.22). For 14 infants, 89 days (range 10-177 days) of interstage monitoring were scheduled. One infant (3.9 %) died during the interstage monitoring. The findings showed a breach of the physiologic criteria for interstage monitoring in seven infants (50 %) after 10 days (range 4-68 days) (five hybrid and two Norwood patients), leading to rehospitalization and catheterization for six patients (four hybrid and two Norwood patients), requiring interventions for two patients (patent arterial duct stent dilation, and atrial septal defect stenting, all for hybrid patients). Overall, three of the seven patients with red flag events of interstage monitoring were candidates for early second-stage surgery. In conclusion, morbidity among infants treated for HLHS remains high, either before or after hospital discharge, emphasizing the need of interstage monitoring programs. Despite retrograde aortic flow in infants with HLHS after the hybrid procedure, the mortality rate was comparable between the two groups. Mortality occurs after early second-stage surgery (<90 days).

Catheter interventions in the staged management of hypoplastic left heart syndrome

AIM

To analyse the current practice and contribution of catheter interventions in the staged management of patients with hypoplastic left heart syndrome.

METHODS

This study is a retrospective case note review of 527 patients undergoing staged Norwood/Fontan palliation at a single centre between 1993 and 2010. Indications and type of catheter interventions were reviewed over a median follow-up period of 7.5 years.

RESULTS

A staged Norwood/Fontan palliation for hypoplastic left heart syndrome was performed in 527 patients. The 30-day survival rate after individual stages was 76.5% at Stage I, 96.3% at Stage II, and 99.4% at Stage III. A total of 348 interventions were performed in 189 out of 527 patients. Freedom from catheter intervention in survivors was 58.2% before Stage II and 46.7% before Stage III. Kaplan-Meier freedom from intervention post Fontan completion was 55% at 10.8 years of follow-up. Post-stage I interventions were mostly directed to relieve aortic arch obstruction--84 balloon angioplasties--and augment pulmonary blood flow--15 right ventricle-to-pulmonary conduit interventions; post-Stage II interventions centred on augmenting size of the left pulmonary artery--73 procedures and abolishing systemic venous collaterals--32 procedures. After Stage III, the focus was on manipulating the size of the fenestration--42 interventions--and the left pulmonary artery -31 procedures.

CONCLUSION

Interventional cardiac catheterisation constitutes an integral part in the staged palliative management of patients with hypoplastic left heart syndrome. Over one-third (37%) of patients undergoing staged palliation required catheter intervention over the follow-up period.

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.

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.

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.

Interventions complementing surgery as part of multistage treatment for hypoplastic left heart syndrome: one center's experience

BACKGROUND

Interventional procedures often are used as part of multistage treatment for hypoplastic left heart syndrome (HLHS). This study aimed to evaluate the efficacy of interventions in multistage treatment of HLHS.

METHODS AND RESULTS

Between 1999 and 2007, 78 interventions were performed for 58 children with HLHS at different stages of surgical treatment. Group 1, involving 30 interventions for 22 patients with postoperative pulmonary arterial stenosis, showed reduced pulmonary artery pressure and increased vessel diameter. Group 2, involving 15 interventions after the Norwood operation for 12 patients with aortic arch obstruction, showed success for 11 patients. Group 3, involving eight balloon angioplasties of narrowed Glenn anastomosis for seven patients, showed abolition of the pressure gradient between the superior vena cava and the right pulmonary artery. Group 4, involving eight interventional closures of a fenestration for eight patients after a Fontan operation, showed increased oxygen saturation for all eight patients. Group 5, involving seven interventions for six patients in whom venovenous collaterals were closed percutaneously, showed improved oxygen saturation. For Group 6, uncommon miscellaneous interventions were used to stabilize the patients' condition before the next surgical treatment.

CONCLUSIONS

Interventional procedures play an important role during multistage treatment of HLHS. They allow for a reduction in the number of operations or stabilization of the patients' condition before the next surgical treatment.