Stent implantation to create interatrial communications in patients with complex congenital heart disease

Left heart decompression by atrial stenting during extracorporeal membrane oxygenation

Persistent severe left ventricular dysfunction during extracorporeal membrane oxygenation (ECMO) requires left heart decompression. We describe stenting of the atrial septum as an alternative emergency approach for left heart decompression during ECMO in addition to the already published surgical and transcatheter approaches.

Modified Technique to Create Diabolo Stent Configuration

Diabolo stent configuration aids in stent positioning, stability, and creating a controlled defect with a predetermined size. A number of techniques to create the diabolo configuration have been previously described. The indications for creating a controlled "defect" are rapidly growing and include the Fontan circulation, patients with severe end-stage pulmonary hypertension, restrictive atrial communication in the setting of hypoplastic right or left heart syndrome, and diastolic left heart failure. We describe an alternative technique using a prefabricated readily available tool (gooseneck snare) to create a diabolo stent configuration. The chosen balloon expandable stent is mounted on a 5-mm gooseneck snare centered on an angioplasty catheter larger than 5 mm diameter. When deployed, the snare restricts the central waist to 5 mm and both ends expand to a larger diameter creating a dumbbell/diabolo configuration. A total of six diablo stent configurations were successfully implanted in four patients with failing Fontan physiology; five to create a transcatheter fenestration and one to relieve atrial septal restriction. Data expressed as median and IQR. Their weight was 24.8 kg (19.6-46.95), and age years was 9.2 (6.28-13.23). There were no complications and a consistent diabolo configuration with a 5-mm central waist was created in all patients. The snare serves as a sterile, preconfigured, radiopaque, readily available tool of adequate length and strength, to create consistent diabolo stent configuration without any modifications. This technique is a simple, reproducible, and easy to learn.

Native atrial septal restriction after Fontan palliation successfully treated with transcatheter Diabolo stent

A 6-year-old male child born with hypoplastic left heart syndrome (HLHS) was palliated with an extracardiac nonfenestrated Fontan procedure (18-mm Gore-Tex tube graft). He developed low-pressure (mean Fontan pressure 10 mmHg) protein-losing enteropathy 6 months after Fontan palliation. After initially responding to medical therapy and transcatheter pulmonary artery stent implantation, he developed medically refractory protein-losing enteropathy. At this time, his transthoracic echocardiogram showed new restriction across his native atrial septum with an 8 mmHg mean gradient. Cardiac catheterization now showed high-pressure (mean Fontan pressure 18-20 mmHg) protein-losing enteropathy and a new 6 mmHg mean gradient across the atrial septum. To avoid cardiopulmonary bypass, he underwent successful transcatheter relief of atrial septal restriction and creation of a fenestration with rapid clinical and biochemical improvement of his protein-losing enteropathy.

Role of stents in congenital heart disease

For more than 10 years, balloon-expandable intravascular stents have become an integral part of treatment for obstructive vascular lesions in children and adults with congenital heart disease. The initial problems with stents, such as sharp edges, rigid frame and unacceptable shortening when over-expanded have been overcome to a large extent with the newer designs. The problems related to delivery of stents, such as stent migration, balloon rupture, flaring of the edges of the stent, rupture of vessels and milking of the stent off the balloon, have also been overcome by newer designs of balloons. The failure of growth of balloon-expandable stents with the growth of the child is managed by redilation with or without additional stenting and newer growth stents. Self-expanding stents are not appropriate for use in growing children due to the limitation of their maximum diameters. The development of biodegradable stents may overcome these disadvantages in the future. Various new developments have recently occurred. Covered stents are ideal for treating acute vessel rupture and in isolating vascular aneurysms. Drug-eluting stents may prevent restenosis, but have not been used in children. Valved stents are a recent innovation for the treatment of regurgitant pulmonary valves.

Shunt reduction to pulmonary arteriovenous malformations using a modified covered stent

Pulmonary arteriovenous malformations in patients with congenital heart disease have been associated with interruption of hepatic venous return to the lungs. We report a novel technique to improve systemic saturation using a modified covered stent in a patient with unilateral left pulmonary arteriovenous malformations in the setting of a Fontan circulation.

New transcatheter techniques for creation or enlargement of atrial septal defects in infants with complex congenital heart disease

OBJECTIVES

To describe a series of 8 consecutive infants (5 with transposition of the great arteries [TGA] and 3 with hypoplastic left heart syndrome [HLHS]) who underwent nonconventional septostomy techniques.

BACKGROUND

For some complex congenital heart defects, an unrestrictive atrial septal defect (ASD) is essential to achieve an adequate cardiac output and/or systemic saturation. In some scenarios, the use of conventional septostomy techniques may be technically difficult, hazardous, and/or ineffective.

METHODS

Use of transhepatic approach, cutting balloons, and radiofrequency perforation with stenting of the atrial septum.

RESULTS

The size of the ASD and the oxygen saturation increased in all patients with no major complications. In those with TGA, the ASDs were considered to be of good size at the arterial switch operation. Two of the 3 patients with hybrid palliation for HLHS have developed some degree of obstruction within the interatrial stent over 2-3 months. At surgery, the stents were found to be secured within the septum with one showing significant fibrous ingrowth after uneventful removal. The other had some nonobstructive ingrowth.

CONCLUSIONS

Creation or enlargement of ASDs in infants using new nonconventional transcatheter techniques is feasible, safe, and effective, at least in the short-to-mid-term follow-up. Infants with TGA seem to benefit the most because the procedure results in satisfactory clinical stability for subsequent early surgical intervention. In infants with HLHS palliated by a hybrid approach, stent implantation to the atrial septum seems to buy enough time to bring them to the phase II safely despite progressive in-stent obstruction.

New Technique for Fenestration of the Interatrial Septum

Achieving controlled flow between the systemic and pulmonary venous circulations is desirable in many complex congenital heart diseases. This includes the Fontan circulation, primary pulmonary hypertension, double inlet ventricles, or hypoplastic left heart with obstruction to the atrioventricular valve. As no specific device is available for this purpose, we developed a balloon-mounted stent technique to achieve a predetermined-sized fenestration of an atrial baffle in a patient with Fontan circulation. The details of the technique are described.

Atrial septostomy using a butterfly stent in a patient with severe pulmonary arterial hypertension

We describe a patient with severe pulmonary artery hypertension and refractory right heart failure who underwent "butterfly" stent atrial septostomy guided by intracardiac ultrasound. This technique may be superior to previously reported blade and balloon septostomy because it allows creation of an atrial septal defect of a precise predetermined diameter. The patient's systemic blood flow and clinical status improved significantly after the procedure, allowing her to be accepted as a candidate for lung transplantation.

Stent implantation for recurrent interatrial obstruction in an infant with hypoplastic left heart syndrome

We report the case of a 19-month-old girl with hypoplastic left heart syndrome who, after Norwood stage 1 and 2 procedures, developed recurrent interatrial obstruction and was treated effectively with stent implantation. The stent was explanted electively 14 months after implantation and showed almost no endothelium formation. Therefore, there was no need for redo atrioseptectomy and the surgical intervention could be staged electively.

"Taking in the Waist": Adjusting the Size of a Stented Fontan Fenestration

Early spontaneous closure of a fenestration following Fontan palliation may complicate the postoperative management of such patients. The creation of a fenestration in the catheterization laboratory with an intravascular stent may improve these patients' hemodynamic status. The aim of this study is to present a new technique to reduce the diameter of stented Fontan fenestrations in those patients in whom the stent diameter is functionally made too large.

Creation and enlargement of atrial defects in congenital heart disease

Transcatheter creation and enlargement of interatrial defects (IAD) may improve hemodynamics; however, procedural outcomes have not been well defined. Hospital records were reviewed for children who underwent percutaneous procedures to create and enlarge an IAD and were grouped as follows: (1) right and (2) left heart obstructive lesions, (3) left atrial (LA) decompression during left heart assist, (4) failing Fontan circulation, and (5) miscellaneous. Forty-five children (mean age, 3.4 +/- 4.7 years; 30 (67%) male) were identified. In group 1 (n = 6), all achieved endpoints of right atrial (RA) decompression (n = 2), improved left ventricular filling (n = 3), or improved arterial saturations (n = 1). In group 2 (n = 18), mean LA pressure decreased (21 +/- 6 to 13 +/- 5 mmHg, p < 0.001) and arterial saturations increased (61 +/- 13% to 78 +/- 11%, p < 0.001). All except 2 patients achieved definitive repair, further palliation (n = 9), or heart transplantation (HTX) (n = 7). In group 3 (n = 5), the LA was decompressed (21 to 13 mmHg, p = 0.03) in all, and all except 1 patient survived to HTX (n = 2) or full recovery (n = 2). In group 4 (n = 11), of 7 patients with a low cardiac output syndrome after surgery, despite improved atrial shunting, 3 died and 1 required a HTX. In group 5 (n = 5), RA decompression (n = 1) or improved arterial saturation (n = 4) was achieved in all. Overall, 5-year HTX free survival was 75%. Mechanical ventilation before the procedure (p < 0.001), the need for a blade septostomy (p = 0.002), and higher LA pressures after the procedure (p = 0.04) independently predicted mortality or the requirement for HTX. Transcatheter optimization of an atrial communication can help optimize treatment strategies and has a low procedural risk.

Transcatheter techniques in the management of perioperative vascular obstruction

The role of transcatheter intervention for the treatment of vascular obstruction is well documented in the preoperative or remote postoperative settings. More recently, the roles of angioplasty and stent implantation have been advocated as intraoperative and immediate postoperative strategies. As one considers the inherent advantages in this cooperative approach to congenital heart disease, the development of a truly hybrid interventional suite seems imperative.

Fenestration in extracardiac conduits in children after modified Fontan operation by implantation of stent grafts

Three patients (ages 3, 5, and 8 years) with various forms of functionally univentricular heart lesions received a total cavopulmonary connection with an extracardiac conduit as a final reconstructive procedure. Failure of the Fontan circulation occurred immediately after surgery because of spontaneous closure of surgical fenestrations in two children and absent fenestration in one. As an emergency procedure, in all patients the conduit was perforated by transcatheter intervention in order to create a connection to the anatomical right atrium. Following balloon dilatation of the perforated conduit, in all three patients covered stent grafts were placed in the newly created defect to attain a reliable communication. Patency of the fenestration was demonstrated by angiogram and any leakage was ruled out. Cardiac output improved and severe pleural effusion and ascites subsided. Right-to-left shunt could be demonstrated by echocardiography at follow-up after 7 months (median) in all three patients. Oxygen saturation remained stable between 85 and 90%. These preliminary results suggest that stent graft fenestration can serve as a valuable tool in failing Fontan circulation, particularly in patients with an extracardiac conduit. Covered stents have the potential to reduce the acute risk of bleeding and they help to prevent early spontaneous closure of the newly created fenestration.

Modified technique of stent fenestration of the atrial septum

OBJECTIVES

To develop a modified technique for stenting the atrial septum in the treatment of patients with a failing Fontan operation or pulmonary hypertension.

SETTING

Two tertiary referral centres.

STUDY DESIGN

Prospective collaborative clinical study.

PATIENTS AND METHODS

A stent was mounted on a standard valvoplasty balloon catheter which was constricted to a predefined diameter by a loop created from a temporary pacing wire. Full balloon inflation created a diabolo shaped stent configuration. The technique was employed in 12 consecutive patients to relieve symptoms of a failing Fontan circulation (n = 6) or severe pulmonary hypertension (n = 6).

RESULTS

Ex vivo studies confirmed that a diabolo shaped stent configuration could be achieved using the above technique. Transcatheter stent implantation was successful in all 12 patients. All six Fontan patients showed significant clinical improvement. Right atrial pressure decreased from (mean (SD)) 16.8 (2.5) to 13.7 (1.9) mm Hg (p < 0.05), and arterial oxygen saturation from 92.8 (1.8)% to 82.7 (3.8)% (p < 0.01). Six patients underwent successful stent fenestration for treatment of pulmonary hypertension. All stents were patent and stable at the most recent follow up (mean 1.75 (1.05) years). No early or late stent related complications were encountered.

CONCLUSIONS

This new technique allows placement of a diabolo shaped stent with a predefined diameter across the atrial septum. The diabolo shape increases stent stability, facilitates recrossing of the stent during future catheter interventions, and ensures medium term stent patency.

Fenestrated Amplatzer device for percutaneous creation of interatrial communication in patients after Fontan operation

A customized Amplatzer septal device with a 5 mm fenestration was used to create an interatrial communication in two patients with previous Fontan operation and clinical indication for fenestration. At follow-up, device fenestration was occluded in both patients. In both patients, the device fenestration was reopened and patency maintained by placement of two stents within the communicating channel.

Open-cell design stents in congenital heart disease: a comparison of IntraStent vs. Palmaz stents

Slotted stainless Palmaz stents (PS) remain the most commonly used in congenital heart disease (CHD). Limitations of PS include rigidity, foreshortening, poor conformability on expansion, balloon rupture, and jailing of side branches. Recently, stents with open-cell design (IntraStent; IS) in appropriate sizes for CHD have been introduced. We reviewed our experience with the IS, comparing performance with the PS in a retrospective nonrandomized, uncontrolled observational study. Between May 1999 and March 2001, 34 IS (10-36 mm) and 34 PS (10-40 mm) were implanted in 57 patients (3 months to 25 years old; median, 3.24 years) in congenital or postoperative lesions. There was no statistically significant difference between the two groups in efficacy, % diameter increase (162% +/- 203% for IS vs. 153% +/- 177% for PS), and % gradient reduction (69% +/- 23% for IS vs. 80% +/- 27% for PS). Other aspects of stent performance differed significantly (P < 0.05): PS forshortened more (mean 18% for PS vs. 0% for IS) and were associated with balloon rupture (9/34 for PS vs. 0/34 for IS; P = 0.002), but had no evidence of intimal protrusion in between struts (0/34 for PS vs. 14/34 for IS; P < 0.001) and no recoil > 15% (0/34 for PS vs. 7/34 for IS; P = 0.006); IS conformed almost twice as well to vessel curvature (P = 0.003). Although these factors did not affect immediate procedural success, balloon rupture in two PS resulted in stent malpositions. Among IS, the origins of three covered side branches were accessed and balloon dilated up to 6 mm through the side of the stent. In conclusion, stents with open-cell design have some characteristics that seem beneficial for their use in CHD: they foreshorten less, are conformable, are less likely to cause balloon rupture, and can allow access to jailed branches. However, they have a higher incidence of significant percent recoil and protrusion of intimal tissue in between struts, which may impact long-term stent performance.

Creation with a stent of an unrestrictive lasting atrial communication

A new technique is presented to create percutaneously an unrestrictive and lasting atrial communication in small children. In 2 infants, a stent was deployed in a restrictive atrial communication and first inflated with an 8 mm balloon. The stent was then further expanded up to 10 or 12 mm. The gradient and turbulent flow between the two atriums disappeared completely. The stent retained a very stable position without embolisation. Other complications, such as formation of thrombus or arrhythmia, were not observed until elective explantation after 2 and 11 months. We conclude that, in infants, dilation of the atrial septum with a stent can provide a safe, lasting, and unrestrictive atrial communication.

Radiofrequency-assisted atrial septoplasty for an intact atrial septum in complex congenital heart disease

Septoplasty of the atrial septum was performed with sequential balloon dilation following radiofrequency-assisted perforation of an intact atrial septum in two newborn infants with hypoplastic left heart syndrome and one with double-outlet right ventricle.

Creation of an intra-atrial communication with a new Amplatzer shunt prosthesis: preliminary results in a swine model

A nitinol shunt device was applied in six minipigs to create a precise intra-atrial shunt. This self-expanding shunt device consists of two retention disks of 2-8 mm, a 4 mm connecting waist with a 10 mm eccentric hole. It requires a 7 Fr introducer sheath. The device is attached to the delivery cable with a microscrew. Placement technique is identical to that of Amplatzer septal occluder. Balloon dilation was performed immediately and 1 month after placement. One animal died from general anesthesia before device placement. Left atrial angiography showed a patent intra-atrial shunt in 5/5 pigs immediately and 4/4 in 1- to 3-month follow up. Postmortem examination demonstrated patent shunts partially or completely neoendothelialized. The shunt device was found to be an effective and safe way to create a permanent atrial communication.

Intravascular and intracardiac stents used in congenital heart disease

Intravascular or intracardiac stenoses occur in many forms of congenital heart disease or after attempted surgical repair. Although balloon dilation is one option for management, restenosis can occur due to elastic recoil immediately after the procedure. To address to such stenotic lesions, many reports support implanting endovascular stents to provide a framework for vessel expansion. Both balloon-expandable fixed tubular mesh stainless steel devices, and self-expandable stents have had an extensive clinical application. In pediatric patients, stents are used for a variety of stenoses, such as systemic venous obstruction pathways (eg, Mustard, Fontan baffle, or bidirectional cavopulmonary connections), pulmonary artery, right ventricular to pulmonary conduits, aortic coarctation, the arterial duct, aorticopulmonary collaterals, or postoperative systemic to pulmonary shunts. Because of improvements in device profile, implantation rates have increased. Complications such as stent fracture, migration, aneurysm formation, and in-stent restenosis occur but only rarely. This latter event may be because of intimal hyperplasia and/or continued vessel (and patient) growth related to the stent diameter. As such, some instances require redilation to manage the acquired lesion. Stent application has importantly altered management algorithms in congenital heart disease.

Pediatric cardiac intensive care: current state of the art and beyond the millennium

Pediatric cardiac intensive care has emerged as a distinct clinical entity to meet the unique needs of pediatric patients with congenital and acquired heart disease. This new subspecialty demands expertise and experience in the pediatric subspecialties of cardiology, intensive care, cardiac surgery, cardiac anesthesia, neonatology, and others. Ten recent developments will have an impact on pediatric cardiac intensive care for the coming decades: 1) emergence of new patient populations; 2) new clinical methodologies in the treatment of pulmonary hypertension; 3) innovations in techniques of respiratory support; 4) expanding research of single ventricle physiology; 5) advances in the treatment of heart failure; 6) improved noninvasive imaging; 7) new directions in interventional cardiac catheterization; 8) new techniques in pediatric cardiac surgery; 9) use of computer technology and intensive care monitoring; and 10) appreciation for global economics of intensive care. Finally, a multidisciplinary approach with a team esprit de corps remains vital to a successful pediatric cardiac intensive care program.