Jeremy M. Ringewald

Procedural Results and Acute Complications in Stenting Native and Recurrent Coarctation of the Aorta in Patients Over 4 Years of Age: A Multi-Institutional Study

Background: We report a multi‐institutional experience with intravascular stenting (IS) for treatment of coarctation of the aorta. Methods and Results: Data was collected retrospectively by review of medical records from 17 institutions. The data was broken down to prior to 2002 and after 2002 for further analysis. A total of 565 procedures were performed with a median age of 15 years (mean = 18.1 years). Successful reduction in the post stent gradient (<20 mm Hg) or increase in post stent coarctation to descending aorta (DAo) ratio of >0.8 was achieved in 97.9% of procedures. There was significant improvement (P < 0.01) in pre versus post stent coarctation dimensions (7.4 mm ± 3.0 mm vs. 14.3 ± 3.2mm), systolic gradient (31.6 mm Hg ± 16.0 mm Hg vs. 2.7 mm Hg ± 4.2 mm Hg) and ratio of the coarctation segment to the DAo (0.43 ± 0.17 vs. 0.85 ± 0.15). Acute complications were encountered in 81/565 (14.3%) procedures. There were two procedure related deaths. Aortic wall complications included: aneurysm formation (n = 6), intimal tears (n = 8), and dissections (n = 9). The risk of aortic dissection increased significantly in patients over the age of 40 years. Technical complications included stent migration (n = 28), and balloon rupture (n = 13). Peripheral vascular complications included cerebral vascular accidents (CVA) (n = 4), peripheral emboli (n = 1), and significant access arterial injury (n = 13). Older age was significantly associated with occurrence of CVAs. A significant decrease in the technical complication rate from 16.3% to 6.1% (P < 0.001) was observed in procedures performed after January 2002. Conclusions: Stent placement for coarctation of aorta is an effective treatment option, though it remains a technically challenging procedure. Technical and aortic complications have decreased over the past 3 years due to, in part, improvement in balloon and stent design. Improvement in our ability to assess aortic wall compliance is essential prior to placement of ISs in older patients with coarctation of the aorta.

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.

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.

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.

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.

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

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.

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 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.