Recent advances in transcatheter pulmonary valve delivery.

PURPOSE OF REVIEW: Transcatheter pulmonary valve replacement has only been both approved and widely available for most congenital heart disease centers for a few years; its use and familiarity for interventionalists have greatly expanded our knowledge of its applicability to a multitude of clinical situations. Expanded worldwide use and longer time from implant have both served to better understand procedural limits and uncommon late adverse events. RECENT FINDINGS: Although currently approved for implantation in the USA only in dysfunctional and circumferential right ventricle to pulmonary artery conduits, with expanded experience operators have been able to adapt the delivery of this valve in a large number of additional clinical scenarios. Rare technical limitations of the procedure, most importantly coronary compression, are now being better defined. Although not frequent, a significant number of infective endocarditis episodes have been reported, but more recently several studies have deepened our understanding of this late adverse event for the most commonly implanted transcatheter pulmonary valve prosthesis. SUMMARY: Expanded and widened use has extended our understanding of who may benefit from transcatheter pulmonary valve implantation (TPVI), the current limits of TPVI, and uncommon but important late issues following TPVI.

Transcatheter pulmonary valve insertion, expanded use (beyond large conduits from the right ventricle to pulmonary artery), and future directions.

Transcatheter pulmonary valve insertion is the most important advance in congenital interventional cardiology since atrial septal defect devices became commonly available 15 years ago. It has changed the way we look at a number of diverse diagnoses and changes how we plan, diagnose, operate, and follow-up patients. It has changed how we counsel families expecting a child that may benefit from it. Expanded use of the Melody® valve, outside its United States Food and Drug Administration approved indications, has helped numerous additional patients. The use of transcatheter pulmonary valve insertion in selected patients following surgical Gore-tex® bileaflet in valve right ventricular outflow tract reconstruction and those with a history of prior small homograft conduits will be discussed.

Transcatheter pulmonary valve insertion, expanded use and future directions.

Transcatheter pulmonary valve replacement with the Melody® valve is an accepted alternative to surgical replacement of the pulmonary valve for some patients and therefore a complementary strategy in the long-term management of several groups of patients with congenital heart disease. It allows at least extending the time between sternotomies and possibly improving late outcomes. With a combined surgical and percutaneous approach, late morbidity for some of these patients will likely be diminished. This manuscript will review the current expanded applications for this technology, demonstrate several examples of its use and discuss future directions for this evolving equipment.

Management of adults with Tetralogy of Fallot.

Tetralogy of Fallot is the most common form of cyanotic congenital cardiac disease. Patients with previously repaired tetralogy of Fallot are the most common patients seen in the Program for Adults with Congenital Heart Disease at The Johns Hopkins All Children's Heart Institute. Guidelines for the management of these patients are available from multiple sources including The American College of Cardiology (ACC) and The American Heart Association (AHA), The Canadian Cardiovascular Society, and The European Society of Cardiology (ESC). These guidelines describe multiple components related to the care for these patients including strategies for medical follow-up, the management of arrhythmias and electrophysiological diseases, and the treatment of chronic pulmonary insufficiency and stenosis. Several new strategies are available for replacement of the pulmonary valve including transcatheter replacement of the pulmonary valve and replacement of the pulmonary valve with a self-manufactured bicuspid polytetrafluoroethylene pulmonary valve.

Transcatheter pulmonary valve insertion: when, how, and why.

Transcatheter pulmonary valve replacement is fast becoming an accepted alternative to repeat surgical pulmonary valve replacement for selected patients and therefore a complementary strategy in the long-term management of those requiring surgical pulmonary valve replacement. With a combined surgical and percutaneous approach, late morbidity for some of these patients may be diminished. This manuscript will review the current indications for this procedure, its limitations, and its benefits.

Pediatric catheterization laboratory anticoagulation with bivalirudin.

BACKGROUND: Pediatric physicians regularly face the problem of uncertain procedural anticoagulation in children, especially in neonates. We sought to evaluate the safety, plasma concentration (pharmacokinetics, PK), pharmacodynamics (PD), and dosing guidelines of bivalirudin when used as a procedural anticoagulant in pediatric percutaneous intravascular procedures. METHODS AND RESULTS: Pediatric subjects undergoing percutaneous intravascular procedures for congenital heart disease were enrolled and received the current weight-based dose used in percutaneous coronary interventions (0.75 mg/kg bolus, 1.75 mg/kg/hr infusion). Blood samples for PK/PD analyses were drawn, and safety was evaluated by monitoring bleeding and thrombosis events. A total of 110 patients (11 neonates, 33 infants, 32 young children, and 34 older children) were enrolled; 106 patients received the protocol dose. The PK/PD response of bivalirudin was predictable and behaved in a manner similar to that in adults. Weight-normalized bivalirudin clearance rates were more rapid in neonates and decreased with increasing age. Bivalirudin concentrations were slightly lower in neonates, with a trend to an increase with age. Activating clotting time response was consistent with adult studies and prolonged in all age groups, and there was reasonable correlation between activating clotting time and bivalirudin plasma concentrations across all age groups. There were few major bleeding (2 of 110, 1.8%) or thrombotic events (9 of 110, 8.2%) reported. CONCLUSIONS: PK/PD response of bivalirudin in the pediatric population is predictable and behaves in a manner similar to that in adults. Using adult dosing, bivalirudin safely provided the expected anticoagulant effect in the pediatric population undergoing intravascular procedures for congenital heart disease.

The hybrid approach--current knowns and unknowns: the perspective of cardiology.

The hybrid approach to the treatment of patients with hypoplastic left heart syndrome most commonly includes transcatheter placement of a stent in the arterial duct and surgical placement of bands on the branch pulmonary arteries via median sternotomy. This manuscript will review the concept of hybrid palliation and discuss topics related to several time intervals: peri-procedural, post-procedural, interstage, and comprehensive stage 2.

Plasma profiling determinants of matrix homeostasis in paediatric dilated cardiomyopathy.

OBJECTIVE: Dilated cardiomyopathy is an important cause of cardiac failure in both children and adults, but is more progressive in children. In adult dilated cardiomyopathy, left ventricular remodelling is associated with changes in the plasma levels of matrix metalloproteinases and tissue inhibitor of metalloproteinases. Plasma matrix metalloproteinases and tissue inhibitors of metalloproteinase changes in paediatric dilated cardiomyopathy have not been examined. This study developed a low blood volume, high-sensitivity assay to test the hypothesis that unique and differential plasma matrix metalloproteinases and tissue inhibitors of metalloproteinase profile exist in patients with paediatric dilated cardiomyopathy. METHODS/RESULTS: A systemic blood sample (1 millilitre) was obtained from seven children aged 8 plus or minus 7 years with dilated cardiomyopathy and 26 age-matched normal volunteers. Using a high-throughput multiplex suspension immunoassay, plasma levels were quantified for collagenases (matrix metalloproteinase-8), gelatinases (matrix metalloproteinase-2 and -9), lysins (matrix metalloproteinase-3 and -7), and tissue inhibitor of metalloproteinases-1, -2, and -4. The matrix metalloproteinase to tissue inhibitors of metalloproteinases ratios were also calculated. The plasma matrix metalloproteinase-2, -7, -8, and -9 levels were increased by greater than twofold in patients with dilated cardiomyopathy than normal patients (with p less than 0.05). Patients with dilated cardiomyopathy also had significantly higher tissue inhibitors of metalloproteinases-1 and -4 (298% and 230%; with p less than 0.05). CONCLUSIONS: These unique findings show that a specific plasma matrix metalloproteinase/tissue inhibitor of metalloproteinase profile occurs in paediatric dilated cardiomyopathy when compared to the cases of normal children. These distinct differences in the determinants of myocardial matrix structure and function may contribute to the natural history of dilated cardiomyopathy in children and may provide a novel biomarker platform in paediatric dilated cardiomyopathy.

Transcatheter Pulmonary Valve Replacement With the Sapien Prosthesis.

BACKGROUND: There are limited published data focused on outcomes of transcatheter pulmonary valve replacement (TPVR) with either a Sapien XT or Sapien 3 (S3) valve. OBJECTIVES: This study sought to report short-term outcomes in a large cohort of patients who underwent TPVR with either a Sapien XT or S3 valve. METHODS: Data were entered retrospectively into a multicenter registry for patients who underwent attempted TPVR with a Sapien XT or S3 valve. Patient-related, procedural, and short-term outcomes data were characterized overall and according to type of right ventricular outflow tract (RVOT) anatomy. RESULTS: Twenty-three centers enrolled a total of 774 patients: 397 (51%) with a native/patched RVOT; 183 (24%) with a conduit; and 194 (25%) with a bioprosthetic valve. The S3 was used in 78% of patients, and the XT was used in 22%, with most patients receiving a 29-mm (39%) or 26-mm (34%) valve. The implant was technically successful in 754 (97.4%) patients. Serious adverse events were reported in 67 patients (10%), with no difference between RVOT anatomy groups. Fourteen patients underwent urgent surgery. Nine patients had a second valve implanted. Among patients with available data, tricuspid valve injury was documented in 11 (1.7%), and 9 others (1.3%) had new moderate or severe regurgitation 2 grades higher than pre-implantation, for 20 (3.0%) total patients with tricuspid valve complications. Valve function at discharge was excellent in most patients, but 58 (8.5%) had moderate or greater pulmonary regurgitation or maximum Doppler gradients >40 mm Hg. During limited follow-up (n = 349; median: 12 months), 9 patients were diagnosed with endocarditis, and 17 additional patients underwent surgical valve replacement or valve-in-valve TPVR. CONCLUSIONS: Acute outcomes after TPVR with balloon-expandable valves were generally excellent in all types of RVOT. Additional data and longer follow-up will be necessary to gain insight into these issues.

Repair of Ebstein's anomaly in the symptomatic neonate: an evolution of technique with 7-year follow-up.

BACKGROUND: Ebstein's anomaly in the severely symptomatic neonate is usually fatal. Until recently, successful repair has not been reported and various palliative operations have been associated with prohibitive mortality. Recently, we published our initial results with biventricular repair in 3 severely symptomatic neonates. We now update our experience with emphasis on the evolution of our surgical technique and the medium-term follow-up of these patients. METHODS: Since 1994, 8 severely symptomatic neonates and young infants underwent biventricular repair by one surgeon. Six had Ebstein's anomaly and 2 had physiologically similar pathology with severe tricuspid valve dysplasia, cyanosis, and gross cardiomegaly. One Ebstein patient (2 months old) had undergone a Starnes operation elsewhere. Weight of the patients at operation ranged from 2.1 to 6.4 kg (mean 2.7 kg). Five patients had either anatomical (n = 3) or functional (n = 2) pulmonary atresia. Severe (4/4) tricuspid regurgitation was present in all except 1 (Starnes operation), and cardiothoracic ratio exceeded 0.85 in all patients. Echocardiography severity scores were >1.5 in 6 (grade 4/4) and 1.3 in 1 (grade 3/4). Repair consisted of tricuspid valve repair, reduction atrioplasty, relief of right ventricular outflow tract obstruction, partial closure of atrial septal defect, and correction of all associated cardiac defects. Technique of tricuspid valve repair evolved over time: 3 had Danielson-type repairs, 3 had DeVega-type repairs, and 2 had complex repairs. RESULTS: One patient died in hospital: a 2.1 kg patient with tricuspid dysplasia, anatomical pulmonary atresia, and hypoplastic pulmonary arteries. The other 7 patients are all in functional class I and in sinus rhythm. Although 3 patients had symptomatic tachyarrhythmias before surgery, no child has experienced SVT after discharge. At recent echocardiography 4 patients had mild tricuspid regurgitation, and 2 had mild-moderate (2/4) tricuspid regurgitation. Three patients are now 7 years old, 2 are almost 2 years old, and the remaining 2 patients are 1 year old. CONCLUSIONS: Surgical repair of the severely symptomatic neonate with Ebstein's anomaly is feasible and safe. The repair appears durable and with good medium-term outcome.

Determinants of extracellular matrix remodelling are differentially expressed in paediatric and adult dilated cardiomyopathy.

AIMS: The left ventricular phenotype of idiopathic dilated cardiomyopathy (DCM) can appear similar in paediatric and adult patients. However, the aetiology of paediatric DCM is usually idiopathic, and often leads an aggressive clinical course. A structural underpinning of DCM is extracellular matrix changes, which are determined by a balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs). This study tested the hypothesis that different MMP/TIMP profiles occur in paediatric and adult DCM patients. METHODS AND RESULTS: Left ventricular samples from paediatric (age 9 ± 5 years; n = 10) and adult (age 62 ± 3 years; n = 20) DCM (at time of transplant) were subjected to an MMP/TIMP multiplex array and immunoassay in order to measure the MMP subclasses; collagenases (MMP-8, -13), gelatinases (MMP-2, -9), stromelysin/matrilysin (MMP-3, -7), membrane type (MT1-MMP), as well as for the four known TIMPs. MMP-8 and -9 levels increased by over 150% (P < 0.05), whereas MMP-3 and -7 levels decreased by over 30% (P < 0.05) in paediatric DCM when compared with adult DCM. TIMP-1 and -2 levels increased two-fold (P < 0.05), but TIMP-3 fell by 41% (P < 0.05) in paediatric DCM. Myocardial levels of specific interleukins (IL-1beta, IL-2, IL-8) were increased by approximately 50% in paediatric DCM. CONCLUSIONS: These unique findings demonstrated that a specific MMP/TIMP profile occurs in paediatric DCM when compared with adult DCM, and that local cytokine induction may contribute to this process. These distinct differences in the determinants of myocardial matrix structure and function may contribute to the natural history of DCM in children.

Rejection with hemodynamic compromise in the current era of pediatric heart transplantation: a multi-institutional study.

BACKGROUND: Survival after pediatric heart transplant has improved over time, as has the incidence of overall rejection. We studied the effect of era on the occurrence and outcome of rejection with hemodynamic compromise (HC). METHODS: Data from 2227 patients who received allografts between 1993 and 2006 at 36 centers in the Pediatric Heart Transplant Study were analyzed to determine incidence, outcome, and risk factors for rejection with HC in early (1993-1999) and recent (2000-2006) eras. Rejection with HC was classified as severe (RSHC) when inotropes were used for circulatory support and mild (RMHC) when inotropes were not used. RESULTS: Of 1217 patients with any episode of rejection, 541 had rejection with HC. Freedom from RMHC improved at 1 year (81% vs 90%, p < 0.001) and at 5 years (74% vs 85%, p < 0.001) in the early vs recent eras, but freedom from RSHC was similar between eras (93% vs 95% at 1 year and 85% vs 87% at 5 years, p = 0.24). Survival after RSHC (63% at 1 year and 49% at 5 years) was worse than after RMHC (87% at 1 year and 72% at 5 years, p < 0.001) and did not change over time. Risk factors for RSHC were non-white race (hazard ratio [HR], 1.73; 95% confidence interval [CI], 1.29-2.32, p < 0.01), older age (HR, 2.85; 95% CI, 1.24-6.53; p = 0.01), and non-A blood type (HR, 1.51;, 95% CI, 1.11-2.04,; p = 0.01), but the only risk factor for RMHC was earlier era of transplant (HR, 1.94; 95% CI, 1.56-2.41; p < 0.001). CONCLUSIONS: The incidence of RMHC has declined over time but the same era effect has not occurred with RSHC. Close follow-up after RSHC is crucial because mortality is so high.

Usefulness of live three-dimensional transesophageal echocardiography in a congenital heart disease center.

Three-dimensional (3D) transesophageal echocardiography (TEE) has numerous potential applications in the care of patients with congenital heart disease (CHD). However, there were few data examining its utility in this setting. The aim was to describe the initial experience and feasibility of this modality at a tertiary CHD center. Twenty-seven 3D-TEE studies using the x7-2t live 3D matrix TEE transducer with an iE33 echocardiographic scanner (Philips Medical Systems, Bothell, Washington) were attempted. The utility of this method was examined in the 3 settings of interventional catheterizations (n = 16), intraoperative studies (n = 4), and diagnostic studies (n = 7). The probe was successfully inserted in 26 of 27 patients (weight 22.6 to 110 kg). In conclusion, the current matrix-array 3D-TEE probe was found to have a wide variety of clinical applications in a CHD center.

Novel minimally invasive, intrapericardial implantable cardioverter defibrillator coil system: a useful approach to arrhythmia therapy in children.

BACKGROUND: Current approaches to implantable cardioverter defibrillator (ICD) implantation in children remain challenging. Transvenous access may be limited due to patient size or anatomy, while epicardial patches require sternotomy or thoracotomy. We present an alternative approach; minimally invasive placement of a transvenous ICD coil within the pericardial space with active fixation. METHODS: Between August 2005 and October 2008, 7 children meeting indications for ICD therapy for ventricular tachyarrhythmias underwent intrapericardial placement of an ICD coil system. Median age was 5 years (range, 1 to 17), weight was 14 kg (range, 8 to 46), and 4 patients weighed less than 20 kg. The ICD system was composed of a single or dual defibrillation coil, an active can, and either ventricular or dual chamber epicardial sense-pace leads. All implantations were performed through a small subxiphoid incision and pericardial window without sternotomy. The coil lead was actively fixated in the transverse sinus under fluoroscopic guidance, and the generator placed in a subrectus pocket in the upper abdomen through the same incision. RESULTS: There were no perioperative complications, and no early or late deaths. All implants had acceptable defibrillation energies (range, 5 to 15 J) that were successfully tested intraoperatively, and none required energy increase or lead revision during follow-up (range, 1 to 39 months; median, 20 months). Impedance between the active can and the defibrillation coil remained stable in all. There were no inappropriate discharges. Thirty-six successful ICD discharges in 4 patients were recorded. Two patients underwent subsequent orthotopic heart transplantation and ICD system removal. CONCLUSIONS: Intrapericardial placement of an ICD coil system can be safely and successfully carried out through a minimally invasive subxiphoid approach in small infants and children. This novel ICD configuration demonstrates excellent performance, and provides a particularly efficacious approach to ventricular tachyarrhythmia therapy in pediatric patients.

Right ventricle-to-pulmonary artery shunt: alternative palliation in infants with inadequate pulmonary blood flow prior to two-ventricle repair.

BACKGROUND: Traditional palliation of infants with biventricular hearts and inadequate pulmonary blood flow is a modified Blalock-Taussig shunt. The aim of this report is to assess the results of an alternative, right ventricle-to-pulmonary artery (RV-PA) shunt. METHODS: Between August 2004 and July 2007, 10 infants with biventricular hearts and inadequate pulmonary blood flow underwent palliation with an RV-PA shunt. Median age was 9 days (range, 4 to 86), weight was 3.0 kg (1.7 to 4.5), and 4 of 10 patients weighed less than 2.5 kg. Shunts were nonvalved Gore-Tex (W.L. Gore Assoc, Flagstaff, AZ), and size was 6 mm (n = 5) or 5 mm (n = 5). RESULTS: There were no operative deaths. Median oxygen saturation at hospital discharge was 95% (87 to 98). In 2 patients the shunt was partially narrowed with a metal clip; they underwent successful balloon dilation 6 months after shunt placement. Eight patients have undergone two-ventricle repair 6 to 17 months after shunt placement. At the time of complete repair, oxygen saturation was 86 +/- 1% and weight was 7.7 +/- 1.7 kg. Repairs included a valved RV-to-PA conduit, 14 to 16 mm in diameter. There was one interstage death. CONCLUSIONS: The RV-PA shunt provides successful palliation in infants with biventricular heart disease and inadequate pulmonary blood flow. It can be used in low birth weight infants and allows significant growth with protection of oxygen saturation prior to complete repair. Partial clipping of the shunt with subsequent balloon dilation is an option to prolong palliation. These results compare favorably with those of a modified Blalock-Taussig shunt or single stage complete repair.

Neoaortic root modification for late thrombosis after Norwood palliation.

A 5-year-old child with hypoplastic left heart syndrome presented with myocardial infarction 2 years after Fontan completion. Evaluation identified a thrombus in his native aortic root. Retrospective review of a prior catheterization revealed stasis in the native aortic root. Surgical thrombectomy was performed after failed medical management. The neoaortic root was revised at the time of thrombectomy in an attempt to reduce stasis in the native aortic root. This case suggests the need to identify anatomic findings that may predispose to coronary artery thrombus formation after Norwood palliation.

Transcatheter device occlusion of multiple large pulmonary arteriovenous malformations in two symptomatic pediatric patients.

Pulmonary arteriovenous malformations (AVMs) large enough to lead to clinically significant cyanosis are rare in the pediatric population. To date, there has been some experience with transcatheter embolization of pulmonary AVMs in children, primarily with coils or balloons. Herein, we report 2 cases of children who were progressively symptomatic and had physical manifestations of hypoxemia arising from large pulmonary AVMs. Both improved after successful catheter-based placement of multiple occlusion devices (Amplatzer vascular plugs) in the pulmonary arterial segments feeding the AVMs produced a rapid, sustained increase in oxygen saturations, and a subsequent amelioration of their symptoms. This represents the first case series of multiple Amplatzer vascular plugs placed into numerous arteriovenous formations, exclusively in children. This approach represents an additional nonsurgical option for children or adults with symptomatic pulmonary AVMs.