Catheter-based interventions for modified Blalock-Taussig shunt obstruction: a 20-year experience

Catheter Intervention for Flow Regulatory Clips on Palliative Shunts and Conduits in Patients with Congenital Heart Disease

Catheter intervention (CI) for a Blalock-Taussig shunt (BTS) or a ventricle-to-pulmonary artery conduit (VPC) is often required after a palliative surgery for congenital heart disease. Flow regulatory clips help improve interstage mortality; their use necessitates CIs to prevent cyanosis. To study the CI outcomes in patients who underwent palliative surgery with either BTSs or VPCs with flow regulatory clips. This single-center retrospective study evaluated demographic characteristics and interventional outcomes of 49 consecutive pediatric patients who required CI for BTS (BTS group) or VPC (VPC group) between January 2008 and September 2018. Overall, 34 and 18 procedures were performed in the BTS and VPC groups, respectively. Moreover, 19/32 (59.3%) and 12/17 (70.1%) patients from the BTS and VPC groups had flow regulatory clips, respectively. All clips were unclipped successfully; one patient in each group underwent staged unclipping. A higher proportion of "clipped patients" underwent CI due to desaturation [clipped vs. non-clipped: BTS, 10/20 (50.0%) vs. 3/14 (21.4%), p = 0.092; VPC, 9/13 (69.2%) vs. 1/5 (20.0%), p = 0.060]. Most clipped patients successfully progressed to the next stage [BTS, 19/20 (95.0%); VPC, 12/13 (92.3%)]. Severe adverse events (SAEs) were more frequent in the VPC group than in the BTS group [3/13 (23.1%) vs. 0/20 (0%), p = 0.024]. Two patients developed an atrioventricular block (requiring an atropine infusion), while one died due to pulmonary overcirculation. While the indication of CI was cyanosis for a higher proportion of clipped patients, all clips were unclipped successfully. The incidence of CI-related SAEs was higher in the VPC group than in the BTS group.

Case Report: Catheter-based mechanical thrombectomy using the Indigo aspiration system in a case of systemic-to-pulmonary shunt thrombosis

A 53-day-old girl with absent right atrioventricular (AV) connection, malposed great vessels, and pulmonary atresia underwent placement of a central shunt on the sixth day of her life. Her postoperative course was complicated by progressive desaturation, and computed tomographic angiography (CTA) demonstrated near-complete occlusion of her left pulmonary artery (LPA). Angiography demonstrated a nonocclusive thrombus in the distal central shunt and a thrombus with complete occlusion of the LPA. The Indigo aspiration system (Penumbra) was used to remove the thrombus from the central shunt and LPA, allowing placement of a stent in the narrowed LPA. Subsequent angiography showed a wide patient central shunt and LPA. The Indigo aspiration system (Penumbra) provides a viable option for removing thrombus in a patients refractory to other methods.

Percutaneous stent implantation for occluded central shunts in adults: A case report and review of current evidence

Background

Patients with cyanotic complex congenital heart defects (CHDs) commonly undergo palliation with interposition of systemic-to-pulmonary shunts (SPSs). These palliative shunts are rarely found in adults with CHDs and can be complicated with progressive obstruction or total occlusion during follow-up. The best treatment option for shunt re-permeabilization is challenging and case-oriented because most patients are high risk candidates for redo surgeries. We aimed to review the current evidence on percutaneous stent implantation to treat failed SPSs.

Methods

We performed a comprehensive literature review on percutaneous stent implantation to treat failed and occluded SPSs. We also reported the case of a 33-year-old man with cyanotic CHD and a occluded central aorto-pulmonary shunt, who was successfully treated with percutaneous balloon dilatation and subsequently stent implantation at our institution.

Result

We identified and included 31 articles reporting on 150 patients and 165 stent implantations in failed SPSs. The age of patients at the time of stent implantation ranged from 6 days to 47 years. The time between the surgical shunt creation and transcatheter intervention ranged from 1 day to 17 years. Overall, 161/165 (97.5%) stent implantations were successful. The most common clinical presentation was cyanosis and decreased atrial oxygen saturations and the indication for stent implantation was shunt obstruction and stenosis.

Conclusion

This review highlights the benefits of endovascular stenting to permeabilize failed SPSs in children and adults with complex CHD who are classified as poor candidates for re-surgical repair.

Multiscale modeling of a modified Blalock-Taussig surgery in a patient-specific tetralogy of Fallot

Tetralogy of Fallot (TOF) is a congenital heart anomaly that causes a drastic reduction in the oxygen level. In this study, we coupled a lumped-parameter model with a patient-specific three-dimensional (3D) model which included a modified Blalock-Taussig (MBT) shunt. By forming a closed loop, we investigated the effects of certain parameters on the flow rates and the pressures at different locations of the developed network. A local sensitivity analysis on an initial zero-dimensional (0D) closed-loop model was conducted. The 0D lumped parameter (LP) model was then refined based on the results of the multiscale 0D-3D model and the local sensitivity analysis was repeated for the refined 0D model. It was shown that the maximum pressure of the pulmonary bed had the highest sensitivity of 94% to the diameter of MBT shunt. We observed that the existence of the flow in the shunt during the diastole caused an elevated wall shear stress (WSS) in the pulmonary artery. In this work, we calculated the flow velocity and pressure field in a 3D patient-specific aorta with an MBT shunt, and then we used the results to increase the accuracy of our LP model to simulate numerous 0D simulations in a significantly shorter time, which is potentially applicable for medical decision-making.

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.

Successful coil embolisation for an arterio-bronchial fistula in a child presenting catastrophic haemoptysis

We report the case of a 2-year-old girl who developed catastrophic haemoptysis due to an arterio-bronchial fistula after transcatheter balloon dilatation for a narrowing aortopulmonary shunt. We embolised the fistula while haemoptysis was controlled with the left bronchial block ventilation and haemostatic balloon occlusion of the left subclavian artery. An arterio-bronchial fistula is an extremely rare complication for balloon dilatation of an aortopulmonary shunt.

Catheter-induced acute Blalock-Taussig shunt thrombosis and bailout

Modified Blalock-Taussig shunt thrombosis is a life-threatening event. We describe an extremely rare catheter-induced shunt thrombosis in an infant with complex CHD and its successful treatment utilising a single low dose of local recombinant tissue plasminogen activator in conjunction with balloon angioplasty.

Surgically placed radiopaque markers: Proof-of-concept of a novel technique to facilitate percutaneous interventions in neonates and infants

OBJECTIVES

Aim of this study was to evaluate feasibility and benefit of self-designed, radiopaque markers as a novel technique in neonates and infants with shunt- or duct-dependent lesions.

BACKGROUND

Surgically placed radiopaque markers have the potential to facilitate postoperative percutaneous interventions.

METHODS

All consecutive children with surgically placed radiopaque markers involving systemic-to-pulmonary artery connections or arterial ducts in the context of hybrid palliation and subsequent cardiac catheterization between January 2013 and March 2019 were included in this analysis. Our primary endpoint was our concept's feasibility, which we defined as a combination of surgical feasibility and the percutaneous intervention's success. Secondary endpoint was the rate of complications resulting from the surgical procedure or during catheterization.

RESULTS

Radiopaque markers that reveal the proximal entry of a surgical shunt or the arterial duct proved to be a feasible and beneficial approach in 25 postoperative catheterizations. The markers' high accuracy enabled easy probing and proper stent positioning in 13 neonates with a median age and weight of 121 days (range 9-356) and 4.7 kg (1.6-9.4) at the intervention. No procedural complications or unanticipated events associated with the radiopaque marker occurred. The markers were never lost, never migrated, and caused no local obstructive lesion. Surgical removal was straightforward in all patients.

CONCLUSIONS

Radiopaque markers are a promising and refined technique to substantially facilitate target vessel access and enabling the accurate positioning of stents during postoperative percutaneous procedures.

Stenting of modified Blalock-Taussig shunt in adult with palliated pulmonary atresia and ventricular septal defect: a case report

Background

Adults with complex congenital heart disease palliated with systemic-to-pulmonary artery shunts have become rare and represent a particularly challenging patient group for the cardiologist. One of the complications and causes of severe clinical deterioration during long-term follow-up are progressive obstruction or total occlusion of the shunt. The risk for surgical intervention is frequently high and catheter intervention may be complicated by complex anatomy and shunt calcification.

Case summary

We report the case of a 47-year-old man with uncorrected (palliated) pulmonary atresia and ventricular septal defect who presented with progressive cyanosis (oxygen saturation 69%) and decreasing exercise capacity. Computed tomography revealed a totally occluded modified left Blalock–Taussig (BT) shunt and a severely stenosed central shunt (Waterston–Cooley) in a patient with confluent but hypoplastic pulmonary arteries and multiple major aortic pulmonary collaterals. Due to a high operative risk, an interventional, percutaneous approach was preferred to re-do surgery. From a radial access the calcified BT shunt could be crossed with a hydrophilic guidewire. Then, a rotational thrombectomy, balloon dilatation, and bare-metal stenting at the proximal and distal anastomoses were performed. Post-interventionally, peripheral oxygen saturation increased from 69% to 82%. Clopidogrel was administered for 1 month after bare-metal stenting. At 1-year follow-up, the BT shunt was still patent on echocardiography and exercise tolerance markedly improved.

Discussion

This case highlights the benefit of percutaneous rotational thrombectomy followed by stenting of chronically occluded systemic-to-pulmonary artery shunts for further palliation in adult patients with complex congenital heart disease not suitable for surgical repair.

Computational Fluid Dynamics Characterization of Two Patient-Specific Systemic-to-Pulmonary Shunts before and after Operation

Studying the haemodynamics of the central shunt (CS) and modified Blalock–Taussig shunt (MBTS) benefits the improvement of postoperative recovery for patients with an aorta-pulmonary shunt. Shunt configurations, including CS and MBTS, are virtually reconstructed for infants A and B based on preoperative CT data, and three-dimensional models of A, 11 months after CS, and B, 8 months after MBTS, are reconstructed based on postoperative CT data. A series of parameters including energy loss, wall shear stress, and shunt ratio are computed from simulation to analyse the haemodynamics of CS and MBTS. Our results showed that the shunt ratio of the CS is approximately 30% higher than the MBTS and velocity distribution in the left pulmonary artery (LPA) and right pulmonary artery (RPA) was closer to a natural development in the CS than the MBTS. However, energy loss of the MBTS is lower, and the MBTS can provide more symmetric pulmonary artery (PA) flow than the CS. With the growth of infants A and B, the shunt ratio of infants was decreased, but maximum wall shear stress and the distribution region of high wall shear stress (WSS) were increased, which raises the probability of thrombosis. For infant A, the preoperative abnormal PA structure directly resulted in asymmetric growth of PA after operation, and the LPA/RPA ratio decreased from 0.49 to 0.25. Insufficient reserved length of the MBTS led to traction phenomena with the growth of infant B; on the one hand, it increased the eddy current, and on the other hand, it increased the flow resistance of anastomosis, promoting asymmetric PA flow.

Intervention on Surgical Systemic-to-Pulmonary Artery Shunts: Carotid Versus Femoral Access

OBJECTIVES

The purpose of this study was to compare results between the femoral arterial (FA) and carotid arterial (CA) approaches in catheter-based interventions on Blalock-Taussig shunts (BTS).

BACKGROUND

Transcatheter intervention on BTS is often performed in shunt-dependent, hypoxemic infants. The approach to BTS intervention likely has an impact on timeliness and overall success.

METHODS

The authors reviewed all cases of catheter intervention for BTS obstruction between 2012 and 2017 for their institution. They sought to compare procedural success rates and time, sheath time, time to arterial access, and time from access to stent implantation between FA and CA approaches.

RESULTS

There were 42 BTS interventions between 34 patients. BTS intervention was more successful from the CA approach (p = 0.035). Among the FA cohort, BTS intervention was unsuccessful in 8 cases (25%), 5 of which were converted to CA with subsequent success. The CA cohort had lower procedure time (62 min vs. 104 min; p = 0.01) and anesthesia time (119 min vs. 151 min; p = 0.01). Additionally, CA access was associated with shorter time to arterial access (4.0 min vs. 9.3 min; p < 0.01), time to placement of the guidewire through the BTS (6.5 min vs. 13 min; p < 0.01), and time from the final sheath to BTS stent implantation (9 min vs. 20 min; p < 0.01).

CONCLUSIONS

Operators should consider the route of access to the BTS deliberately. The authors' approach has been the carotid artery as an alternative access site-associated with greater procedural success, shorter procedural time, and shorter time to stent implantation.