Balloon dilatation of a stenosed modified (polytetrafluoroethylene) Blalock-Taussig shunt

Off-Label use of Stretchable Polytetrafluoroethylene: Overexpansion of Synthetic Shunts

Purpose

To describe our experience with balloon dilatation and stenting of modified systemic-to-pulmonary artery (PA) shunts in relation to an assessment and interpretation of the mechanical properties of thin-walled expandable polytetrafluoroethylene (ePTFE) stretch vascular grafts.

Methods

Our pediatric cardiology/cardiac surgery database was reviewed to identify all infants and children with a modified systemic-to-PA shunt who underwent cardiac catheterization. Reports and images were reviewed. Thin-walled stretchable and regular Gore-Tex® vascular grafts were mechanically compared using tensiometry.

Results

11 patients underwent dilatation or stenting procedures of a systemic-to-PA shunt. No major complications occurred and none of our patients died during or due to this intervention. High pressures in balloons and stents with diameters larger than the graft were used. Shunt diameters and oxygen saturation levels increased from 2.05 ± 1.25 mm to 4.75 ± 0.88 mm and with 12 ± 6.8%, respectively. In 6 patients re-catheterizations were performed. Four patients died, all with patent shunts. The fail-stress and the fail-strain in the circumferential direction of the stretchable graft were significantly higher than in the non-stretchable graft.

Conclusions

Dilatation and stenting of stenosed modified systemic-to-PA shunts is feasible and safe. Dilatation and stenting of these shunts to calibers larger than those provided by the manufacturer is possible. Results of our technical study posit a great advantage for the use of the thin-walled stretch configuration of ePTFE.

Percutaneous intervention for central shunts: new routes, new strategies

Introduction In traditional locations, the standard Blalock-Taussig shunt presents numerous technical difficulties for percutaneous intervention. We changed our strategy to a central type shunt (Laks-type) with end-to-side pulmonary and side-to-side aortic anastomosis. The aim of this study was to determine whether this modified strategy would allow easier percutaneous manipulation in patients with small pulmonary arteries. Methods All children with a stretchable central vascular graft who required any form of percutaneous intervention were prospectively enrolled in the study. Results Eleven infants were evaluated a median time of 3 months (range 0.9-4.4) following initial shunt placement; the median weight at intervention was 5.7 kg (range: 4.0 - 10.0). All shunts (100%) were easily and swiftly entered without the need for special catheters or co-axial systems. In four patients other interventions in distal pulmonary arteries were first performed: cutting balloon treatment in three and balloon angioplasty of peripheral pulmonary artery stenosis in one. The shunts were then augmented with a stent with a diameter increasing from 3.5 ± 0.4 mm to 4.7 ± 0.8 mm and saturation increasing from 76% (range: 69-88) to 84% (range: 77-88) (P < 0.05). Several months later, two children required further interventions that could easily be performed via the stented shunts. No complications were observed. Conclusions The Laks-type shunt provides easy access for percutaneous procedures of the distal pulmonary arteries including cutting balloons; this shunt can predictably be expanded to augment pulmonary flow. This study highlights how co-operation between the interventionalist and the surgeon can improve strategies to manage these difficult patients.

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

Thrombotic occlusion of a modified Blalock-Taussig (BT) shunt is rare, leading to life-threatening hypoxemia. Rescue percutaneous interventions may allow recanalization of the systemic-to-pulmonary shunt but data on large patients' scales are lacking. We aimed to describe safety and effectiveness of catheter-based interventions to restore modified BT shunt patency. All patients who attempted transcatheter intervention for thrombotic occlusion of a modified BT shunt at our Institution from 1994 to 2014 were reviewed. Characteristics, management, and outcomes of the 28 identified patients were analyzed. Thirty-three procedures were performed at a median age of 0.6 years old (range 0.03-32.1 years) and a median weight of 5.8 kg (range 2.2-82 kg). Percutaneous intervention consisted in 33 balloon angioplasty (100 %) and 14 stent implantations (42.4 %). Thrombolytic agents were also used in 6.1 % cases. No peri-procedural death occurred but complications were observed in five patients (15.2 %), including one catheter-induced transient complete atrioventricular block, one cardiac tamponade, and one massive thrombo-embolic stroke. Early procedural success was obtained in 28 patients (84.8 %) and remained long-lasting in 26 patients (78.8 %). A young age and a low body-weight at the time of the procedure were significantly associated with procedural failure (p = 0.0364 and p = 0.0247, respectively). Although technically challenging and carrying potential major complications, transcatheter intervention can be considered as an efficient rescue strategy to restore patency in case of thrombotic obstruction of a modified BT shunt.

Percutaneous upsizing of a Blalock-Taussig shunt

Percutaneous upsizing of surgically placed Blalock-Taussig shunts is an uncommon practice. We report the case of an 8-month-old infant with single-ventricle physiology, who - due to comorbidities - was deemed unsuitable to proceed with Glenn operation. The 3.5-millimetre Blalock-Taussig shunt was stented successfully with a 5-millimetre pre-mounted stent, resulting in an increase in shunt diameter and oxygen saturation by nearly 30% and 10%, respectively.

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.

Endovascular stents for relief of cyanosis in single-ventricle patients with shunt or conduit-dependent pulmonary blood flow

Hypoxemia is a significant cause of early and interstage death in patients with single ventricle (SV). Obstruction of Blalock-Taussig shunts (BTS) in patients with SV has traditionally been managed with surgical revision.

PURPOSE

We report on the experience at our institution of deploying endovascular stents within BTS as well as obstructed right-ventricle (RV) to pulmonary artery (PA) conduits in patients with modified Norwood (ie Sano modification).

METHODS

Medical records were reviewed for the time period between January 1, 2002 and November 30, 2005. All patients with SV who presented for intervention for BTS or RV-PA conduit stenosis were reviewed. Specific endpoints reviewed included pre- and post-intervention arterial oxygen saturation, type of intervention (stent vs. ballon dilation), need for subsequent surgical shunt/conduit revision, and interval to second stage palliation.

RESULTS

Fifteen patients with SV underwent intervention for acute cyanosis. Eight patients had BTS, and the other seven patients had RV-PA conduit stenosis. Coronary stents were deployed in 14 of the 15 patients. Four patients also underwent balloon angioplasty of branch PAs. Oxygen saturations improved in all patients, with a mean increase of 13.9% (p = 0.0001). Four patients died before second stage palliation--one due to complications of the catheterization. Of the eleven remaining patients, nine have undergone second stage palliation; interval from intervention to Glenn ranged from 28-205 days (mean 163d). Two patients are awaiting cavo-pulmonary anastamosis.

CONCLUSIONS

Endovascular stenting in this high-risk population is effective at improving oxygen saturation as well as obviating need to surgical shunt/conduit revision.

Balloon angioplasty for Blalock-Taussig shunt failure in the early postoperative period

Blalock-Taussig shunt failure is an infrequent but devastating, and often life-threatening, postoperative complication. Percutaneous balloon angioplasty (BA) of a stenotic modified Blalock-Taussig shunt (mBTS) has been successfully used in the setting of progressive shunt failure months to years after shunt creation. Only a few case reports exist where BA was used in the early postoperative period. We report a case series of urgent balloon angioplasty for acute early postoperative mBTS failure. Five patients were performed with BA. BA was performed within the first 24 hr following mBTS placement in three patients. Mean total procedure time was 57 min (range, 34-77 min) and mean total fluoroscopic time was 13.8 min (range, 6.4-24.1 min). Immediate success, defined as increased angiographic diameter, was accomplished in 4/5 procedures. One patient died during the procedure. Two patients survived to Glenn procedure. One patient underwent redo mBTS and one died the day after the BA. In selected patients, BA can relieve acute thrombosis of mBTS. The risk for reintervention and death is high.

Balloon angioplasty for obstructed modified systemic-pulmonary artery shunts and pulmonary artery stenoses

OBJECTIVES

The results of percutaneous balloon angioplasty for obstructed modified Blalock-Taussig (BT) or central shunts and pulmonary artery (PA) stenoses were studied to assess its role as an alternative to second shunt and surgical PA angioplasty.

BACKGROUND

Obstruction of a modified shunt and PA stenosis related to the shunt or ductus are not infrequent. A second shunt with or without PA angioplastv is required if the PA size, morphology or age of the patient is suboptimal for definitive surgery.

METHODS

From June 1994 to May 1999, balloon angioplasty for obstructed systemic-to-PA shunts was performed in 46 patients, with ages ranging from 1 month to 7.4 years (2.2 +/- 1.9 years). Among the 46 patients, 32 had modified BT shunts, 5 had bilateral shunts, 7 had modified central shunts, and 2 had both modified BT and central shunts. Stenoses were seen in 27 main branch PAs, and interruption was present in three. A concurrent balloon angioplasty was attempted in 28 main branch PAs, but it was performed in only 25 vessels.

RESULTS

Balloon dilation for obstructed modified shunts was considered to be effective in 42 patients (91%), while angioplasty for PA stenosis was effective in 14 vessels and not effective in 11 vessels. After balloon dilation angioplastv, oxygen saturation in the aorta increased from 74.4 +/- 4.3% to 80.8 +/- 3.6% (p < 0.01) in these 46 patients. One patient died of pneumonia. Eight patients required an additional modified BT shunt soon after the procedure because of severe stenosis or interruption at main branch PA. After a mean follow-up period of 11.6 +/- 5.4 months, 29 patients underwent a repeated imaging study to evaluate the morphology and size of the PAs. Of these 29 patients, 26 underwent open-heart surgery, with two mortalities.

CONCLUSIONS

When a second shunt is under consideration because of obstruction of the modified shunt, balloon angioplasty is a possible alternative procedure. Pulmonary artery stenosis, if present, can be simultaneously dilated.

Recanalization of an occluded modified Blalock-Taussig shunt by balloon angioplasty within 12 hours of its construction

An infant developed severe desaturation within a few hours of construction of a modified Blalock-Taussig shunt. Echocardiography revealed that the shunt had become occluded, and this was confirmed angiographically. At catheterisation, therefore, we passed a 0.014" percutaneous transluminal coronary angioplasty wire through the occluded shunt into the right pulmonary artery and then dilated the shunt successfully using a 5 mm coronary angioplasty balloon. Six weeks later, the shunt remained patent.

Recommendations of the British Paediatric Cardiac Association for therapeutic cardiac catheterisation in congenital cardiac disease

The aims of these recommendations are to improve the outcome for patients after, and to provide acceptable standards of practice of therapeutic cardiac catheterisation performed to treat congenital cardiac disease. The scope of the recommendations includes all interventional procedures, recognising that for some congenital malformations, surgical treatment is equally as effective as, or occasionally preferable to, interventional treatment. The limitations of the recommendations are that, at present, no data are available which compare the results of interventional treatment with surgery, and certainly none which evaluate the numbers and types of procedures that need to be performed for the maintenance of skills. Thus, there is a recognised need to collect comprehensive data with which these recommendations could be reviewed in the future, and re-written as evidence-based guidelines. Such a review will have to take into account the methods of collection of data, their effectiveness, and the latest developments in technology. The present recommendations should, therefore, be considered as consensus statements, and as describing accepted practice, which could be used as a basis for ensuring and improving the quality of future care.

Emergent stent placement for acute Blalock-Taussig shunt obstruction after stage 1 Norwood surgery

A neonate underwent a stage 1 Norwood surgery for hypoplastic left heart syndrome and subsequently developed profound cyanosis and hemodynamic instability. Catheterization revealed an occluded modified Blalock-Taussig shunt. Angioplasty and stent implantation resulted in immediate angiographic and clinical improvement, which has persisted at 5-month follow-up. This therapy may provide lifesaving treatment in selected patients.

Percutaneous balloon angioplasty for early postoperative modified Blalock-Taussig shunt failure

Percutaneous balloon angioplasty was successful initial treatment for 2 infants who, early after operation, developed obstruction at the proximal anastomotic site of a modified Blalock-Taussig shunt. Two years later the first child had not required reoperation and the dilatation site was patent angiographically. The other baby progressed well after angioplasty but because of surgical concern about the long-term success of angioplasty, shunt surgery was repeated, the baby dying after reoperation. Angioplasty of proximal obstruction in these shunts is feasible and satisfactory long-term palliation can be achieved avoiding repeat shunt surgery before the more definitive Fontan-type procedure.

Transcatheter treatment of pulmonary outflow tract obstruction: a review

The role of transcatheter methods in the management of pulmonary outflow tract obstruction are discussed in this review. Balloon pulmonary valvuloplasty for relief of isolated pulmonary valve stenosis has been successfully used by many investigators and is the procedure of choice for the management of these lesions. Supravalvar pulmonic stenosis, if discrete, can be relieved by balloon dilatation. Cyanotic children with interatrial right-to-left shunts secondary to severe valvar pulmonary stenosis respond in a manner similar to that observed with isolated pulmonary valve stenosis. In these patients, balloon valvuloplasty is the treatment of choice and may be corrective in most patients. In patients with interventricular right-to-left shunting secondary to pulmonary outflow tract obstruction and in patients with narrowed BT shunts, balloon dilatation may be an effective palliative procedure in a substantial proportion of patients obviating the need for an initial or second palliative shunt. Balloon dilatation is recommended if the patient's size or cardiac anatomy make them unsuitable for safe total surgical correction. In patients with pulmonary atresia, either initial opening of the atretic pulmonary valve by laser or by surgery with subsequent balloon dilatation are potentially beneficial in reducing the total number of surgical procedures that these children are likely to require. However, further clinical trials are needed before their general use.

Transcatheter management of cyanotic congenital heart defects: a review

In this review, the role of transcatheter methods in the management of cyanotic congenital heart defects is discussed. In patients with interventricular right-to-left shunting secondary to pulmonary outflow tract obstruction (most commonly tetralogy of Fallot), balloon dilatation may be an effective palliative procedure in a substantial proportion of patients, obviating the need for a palliative shunt. We would recommend this if the patient's size or cardiac anatomy makes that patient an unsuitable candidate for safe total surgical correction. Infundibular myectomy with atherectomy catheter in tetralogy of Fallot patients may become a useful adjunct in the management of these infants. Cyanotic children with interatrial right-to-left shunt secondary to severe valvar pulmonary stenosis respond to balloon pulmonary valvuloplasty in a manner similar to that seen with isolated pulmonary valve stenosis. In these patients, balloon valvuloplasty is the treatment of choice and may be corrective in most cases. In patients with a narrowed Blalock-Taussig shunt, balloon angioplasty may improve pulmonary oligemia and systemic arterial hypoxemia and may obviate the need for a second systemic-to-pulmonary artery shunt. Balloon angioplasty is recommended if the patient's cardiac defect is not amenable to surgical correction at a low risk either because of the size of the patient or because of the complexity of the cyanotic heart defect. In patients with pulmonary valve atresia, initial opening of the atretic pulmonary valve by either laser or surgery with subsequent balloon dilatation is potentially beneficial in reducing the total number of surgical procedures that these children are likely to require. However, further clinical trials are needed prior to their general use.

Balloon dilatation of a stenosed aortic homograft conduit following repair of the common arterial trunk

An 8-year-old boy, who underwent surgical correction of a common arterial trunk at the age of 10 months, developed stenosis of the 15-mm aortic homograft. Chest x-ray demonstrated calcification of the homograft, and at cardiac catheterization there was a 57 mmHg gradient across the conduit. He underwent balloon dilatation using a 15-mm balloon catheter. After four inflations at a pressure of 5.5 atm, the gradient decreased to 34 mmHg. Six months later he had a Doppler-estimated gradient of 38 mmHg.

Magnetic resonance imaging of the great arteries in infants

Sixty infants, aged 1-48 (median 8) weeks, with suspected congenital heart disease underwent a morphological evaluation of the great arteries using magnetic resonance imaging at 1.5 Tesla. Cross-sectional echocardiography was performed in all infants, angiography in 33 and surgery in 44. Multiple sections, 5 mm thick and gated to the patients' electrocardiogram were acquired in standard and oblique imaging planes. Ventriculo-arterial connexions were correctly identified in 54 infants (6 did not have intracardiac imaging performed) and an accurate description of the relationships of the great arteries was made in all. Magnetic resonance imaging clearly demonstrated normal and hypoplastic pulmonary arteries to the level of the first hilar branches and was better than echocardiography at confirming the presence or absence of central intrapericardial pulmonary arteries in 4 infants with pulmonary atresia. All parts of the thoracic aorta were accurately demonstrated and, in 23 infants with clinical suspicion of aortic coarctation, magnetic resonance images provided more information than echocardiography. Magnetic resonance imaging accurately demonstrates great arteries non-invasively supplementing echocardiographic and angiographic findings. In many cases, it replaces the need for invasive investigations.