Transvenous and non-transvenous implantable cardioverter-defibrillators in children, adolescents, and adults with congenital heart disease: who is at risk for appropriate and inappropriate shocks?

AIMS: Non-transvenous implantable cardioverter-defibrillators (ICDs) as used in small patients and in patients with congenital heart disease (CHD) have not been compared with transvenous systems with respect to safety and efficacy yet. Aim of the present study was to describe the prevalence of and to identify contributing factors for appropriate and inappropriate ICD discharges in patients with non-transvenous and transvenous ICD. METHODS AND RESULTS: Single centre analysis of all paediatric and CHD patients who had received an ICD since 1995. One hundred and ninety-five patients were included. A transvenous system had been implanted in 153 (78%) subjects, the remaining 42 (22%) individuals received an extracardiac (EC)-ICD system. During mean follow-up of 4.5 years appropriate ICD shocks were noted in 32 (16%) individuals, whereas inappropriate shocks occurred in 22 (11%) patients. Appropriate shocks were more frequent in patients with an EC-ICD than in individuals with transvenous systems (29% vs. 13%, P = 0.02). Rapidly conducted atrial tachycardia (AT) was the most common reason for inappropriate shocks (76%). Rate of inappropriate shocks was not different between EC and transvenous systems (12% vs. 11%, P = 0.26). Lead failure was more prevalent in subjects with an EC-ICD (29% vs. 7%, P = 0.001). CONCLUSION: Individuals with EC-ICD systems were particularly prone to experience appropriate shocks. As rapidly conducted AT was the most common reason for inappropriate ICD shocks, rigorous treatment of these arrhythmias and proper ICD programming are mandatory. Though lead failure was of concern in EC-ICD patients, EC-ICD systems were not inferior with respect to inappropriate shocks.

Monitoring of regional lung ventilation using electrical impedance tomography after cardiac surgery in infants and children.

Electrical impedance tomography (EIT) is a noninvasive method to monitor regional lung ventilation in infants and children without using radiation. The objective of this prospective study was to determine the value of EIT as an additional monitoring tool to assess regional lung ventilation after pediatric cardiac surgery for congenital heart disease in infants and children. EIT monitoring was performed in a prospective study comprising 30 pediatric patients who were mechanically ventilated after cardiac surgery. Data were analyzed off-line with respect to regional lung ventilation in different clinical situations. EIT data were correlated with respirator settings and arterial carbon dioxide (CO2) partial pressure in the blood. In 29 of 30 patients, regional ventilation of the lung could sufficiently and reliably be monitored by means of EIT. The effects of the transition from mechanical ventilation to spontaneous breathing after extubation on regional lung ventilation were studied. After extubation, a significant decrease of relative impedance changes was evident. In addition, a negative correlation of arterial CO2 partial pressure and relative impedance changes could be shown. EIT was sufficient to discriminate differences of regional lung ventilation in children and adolescents after cardiac surgery. EIT reliably provided additional information on regional lung ventilation in children after cardiac surgery. Neither chest tubes nor pacemaker wires nor the intensive care unit environment interfered with the application of EIT. EIT therefore may be used as an additional real-time monitoring tool in pediatric cardiac intensive care because it is noninvasive.

Aortic surgery after previous procedure of congenital aortic stenosis.

Irrespective of previous procedure in congenital aortic stenosis, aortic surgery later in life may be indicated. The aim of the present study was the analysis of indications, risks, and outcomes of aortic surgery after previous aortic valve procedure. The data of patients who underwent aortic surgery after previous treatment of congenital aortic stenosis in a 10-year period (from 2000 to 2009) were retrospectively analyzed. Thirty-two patients (23 male and 9 female) underwent redo aortic surgery. The mean age at surgery was 13.5 ± 11.3 years. Seventeen patients had undergone initial aortic balloon valvuloplasty (BVP) and 15 patients open commissurotomy (COM). Nine cases had undergone the primary procedure at neonatal age and two patients had undergone cardiac surgery before the initial aortic valve procedure. Seven of the patients with previous COM (43.8%) had undergone concomitant surgery along with initial commissurotomy. A reintervention within the first year after the primary procedure was performed in seven patients (seven after BVP and none after COM; P < 0.05). The interval between the last intervention and the first redo aortic surgery was 7.5 ± 9.5 years (3.1 ± 3.5 years after BVP vs. 12.5 ± 11.7 years after COM; P < 0.05). A second redo surgery was performed in nine patients (four after initial BVP and five after COM). Congenital aortic stenosis is very often presented in combination with additional pathologies. These concomitant diseases along with the underlying disease give the indication for reoperation. Reinterventions are more often indicated after primary BVP. Long follow-up in specialized centers is mandatory.

Severe constrictive pericarditis after parvovirus B19 and human herpes virus 6 infection in a 9-year-old girl.

We report on a 9-year-old girl who developed signs of congestive heart failure with significant ascites due to constrictive pericarditis. Cardiac catheterization was performed to establish the diagnosis and to rule out restrictive cardiomyopathy. Endomyocardial biopsies were positive for activated macrophages and small-vessel disease, but no viral genomes were detected. Open pericardectomy was performed and histopathologic examination of the resected thickened pericardium showed extensive fibrosis and hyaline degeneration. A combined infection with parvovirus B19 (PVB19) and human herpes virus 6 (HHV6; subtype B) was proven within the resected pericardium. We suggest that local HHV6-induced immunosuppression enhanced the PVB19 infection, thus resulting in chronic infection and leading to constrictive pericarditis.

Extracorporeal circulation for rewarming in drowning and near-drowning pediatric patients.

Drowning and near-drowning is often associated with severe hypothermia requiring active core rewarming.We performed rewarming by cardiopulmonary bypass(CPB). Between 1987 and 2007, 13 children (9 boys and 4 girls) with accidental hypothermia were rewarmed by extracorporeal circulation (ECC) in our institution. The average age of the patients was 3.2 years. Resuscitation was started immediately upon the arrival of the rescue team and was continuously performed during the transportation.All patients were intubated and ventilated. Core temperature at admission ranged from 20 to 29°C (mean 25.3°C). Connection to the CPB was performed by thoracic (9 patients) or femoral/iliac means (4 patients). Restoration of circulation was achieved in 11 patients (84.6%). After CPB termination two patients needed an extracorporeal membrane oxygenation system due to severe pulmonary edema.Five patients were discharged from hospital after prolonged hospital stay. During follow-up, two patients died(10 and 15 months, respectively) of pulmonary complications and one patient was lost to follow-up. The two remaining survivors were without neurological deficit.Modes of rewarming, age, sex, rectal temperature, and serum electrolytes did not influence mortality. In conclusion,drowning and near-drowning with severe hypothermia remains a challenging emergency. Rewarming by ECC provides efficient rewarming and full circulatory support.Although nearly half of the children may survive after rewarming by ECC, long-term outcome is limited by pulmonary and neurological complications.

Aortic valve surgery in congenital heart disease: a single-center experience.

The optimal treatment of congenital aortic valve lesions is a controversial issue. This study was performed to evaluate the outcome after surgical treatment of aortic valve lesions in congenital aortic valve disease. Between the years of 2000 and 2008, 61 patients (mean age: 12.6 +/- 9.6 years, range: 1 day to 40 years) underwent aortic valve surgery for congenital aortic valve disease. Twenty-four patients had undergone previous cardiovascular operations. Indications for surgery were aortic regurgitation in 14.7% (n = 9), aortic stenoses in 26.2% (n = 16), and mixed disease in 59.1% (n = 36). The Ross procedure was performed in 37.7% (n = 23), aortic valve replacement with biological or mechanical prostheses in 29.5% (n = 18). Concomitant procedures were performed in 91.8% (n = 56) due to associated congenital cardiac defects. The overall mortality rate was 5%. Six patients needed reoperation. Implantation of permanent pacemakers occurred in six patients for permanent atrioventricular block. At the latest clinical evaluation, all survivors are in New York Heart Association class I-II and are living normal lives. Aortic valve surgeries in patients with congenital heart disease have had low mortality and morbidity rates in our series. Surgical technique as well as timing should be tailored for each patient. Aortic valve replacement should be delayed until the implantation of an adult-sized prosthesis is possible.

Feasibility of implantable cardioverter defibrillator treatment in five patients with familial Friedreich's ataxia--a case series.

Friedreich's ataxia (FRA) is an autosomal recessive disease of the central nervous system that is associated with familial cardiomyopathy. Cardiac involvement is seen in more than 90% of the patients and is the most common cause of death in these patients. We present a case series and discuss the indications for implantable cardioverter defibrillator (ICD) implantation in FRA with review of the literature. Five pediatric patients who suffer from FRA (four female and one male, mean age 17.4 years) underwent ICD implantation between 2007 and 2008 in the University Hospital of Goettingen. The diagnosis of FRA was established by standard clinical criteria and proven in each case by genotyping at the frataxin locus. The time from diagnosis to ICD implantation was 10.4±1.73 years (range 8-15 years). All patients received transvenous lead systems. There were no intraoperative and postoperative complications. At the latest follow-up, the neuromuscular symptoms exhibited no further progress and no ICD activations were noticed. Only minor repolarization changes were seen on electrocardiogram. All patients had normal echocardiographic findings and no angina has been reported. Coronary angiographies were normal. It is evident that many FRA patients develop ventricular dysfunction. In the absence of a definitive surgical cure an ICD is generally indicated in young patients with hemodynamically significant sustained ventricular tachyarrhythmias for prevention of sudden cardiac death. Our experience implies the safe use of ICD in children with FRA.

Indications for reoperation late after correction of tetralogy of Fallot.

OBJECTIVE: Correction of tetralogy of Fallot has excellent long-term results. The present retrospective study investigates the indications for reoperation late after corrective surgery. METHODS: Data from 914 consecutive cases who underwent correction of tetralogy of Fallot in our department between 1960 and 2002 were retrospectively reviewed and analysed. In 91 patients, a total of 102 reoperations were performed late after repair. RESULTS: The mean time interval between corrective surgery and the first reoperation was 12.8 years. The main indication for reoperation was residual ventricular septal defect in nearly half of the cases, mostly isolated, but also in combination with a right ventricular outflow tract aneurysm or pulmonary stenosis. One-fourth of reoperated patients underwent a procedure on their pulmonary artery or pulmonary valve: replacement of pulmonary valve, replacement of primary implanted pulmonary artery conduits with or without concomitant surgery, and surgery for isolated peripheral pulmonary stenosis. The remaining indications were right ventricular outflow tract aneurysms and others. Aneurysms of the right ventricular outflow tract were seen mostly after the use of autologous - untreated - pericardial patch in 18 of 21 cases. CONCLUSION: The number of reoperations for residual ventricular septal defect decreased during the study period. The primary use of conduits led to an increased number of reoperations for conduit exchange due to degeneration or failure. Use of an untreated autologous pericardial patch for enlargement of the right ventricular outflow tract should be avoided due to increased risk for aneurysm formation.

Mechanical aortic valve replacement in children and adolescents after previous repair of congenital heart disease.

Due to improved outcome after surgery for congenital heart defects, children, adolescents, and grown-ups with congenital heart defects become an increasing population. In order to evaluate operative risk and early outcome after mechanical aortic valve replacement (AVR) in this population, we reviewed patients who underwent previous repair of congenital heart defects. Between July 2002 and November 2008, 15 (10 male and 5 female) consecutive patients (mean age 14.5 +/- 10.5 years) underwent mechanical AVR. Hemodynamic indications for AVR were aortic stenosis in four (27%), aortic insufficiency in eight (53%), and mixed disease in three (20%) after previous repair of congenital heart defects. All patients had undergone one or more previous cardiovascular operations due to any congenital heart disease. Concomitant cardiac procedures were performed in all of them. In addition to AVR, in two patients, a mitral valve exchange was performed. One patient received a right ventricle-pulmonary artery conduit replacement as concomitant procedure. The mean size of implanted valves was 23 mm (range 17-29 mm). There were neither early deaths nor late mortality until December 2008. Reoperations were necessary in five (33%) and included implantation of a permanent pacemaker due to complete atrioventricular block in two (15%), mitral valve replacement with a mechanical prosthesis due to moderate to severe mitral regurgitation in one (7%), aortocoronary bypass grafting due to stenosis of a coronary artery in one (7%), and in one (7%), a redo subaortic stenosis resection was performed because of a secondary subaortic stenosis. At the latest clinical evaluation, all patients were in good clinical condition without a pathological increased gradient across the aortic valve prosthesis or paravalvular leakage in echocardiography. Mechanical AVR has excellent results in patients after previous repair of congenital heart defects in childhood, even in combination with complex concomitant procedures. Previous operations do not significantly affect postoperative outcome.

Efficacy and safety of non-transvenous cardioverter defibrillators in infants and young children.

BACKGROUND: Implantable cardioverter defibrillators (ICD) protect from sudden cardiac death (SCD). In infants and young children, ICD implantation and programming is challenging due to small body size, elevated heart rates, and high physical activity. PURPOSE: We report our experience applying a non-transvenous ICD (NT-ICD) system to infants and children < 12 years of age and < 45-kg body weight. METHODS: Between 07/2004 and 07/2016, NT-ICD had been implanted in 36 patients. Nine out of 36 patients (25%) had NT-ICD implantation for primary and 27/36 (75%) for secondary prevention. Underlying diseases included inherited primary electrical arrhythmogenic diseases (n = 26; 72%), cardiomyopathies (n = 8; 22%), and congenital heart defects (n = 2; 6%). The median (interquartile range) age at implantation was 6 (1.9-8.4) years, and the median body weight was 21.7 (11.2-26.8) kg. Three different NT-ICD implantation techniques had been applied over time: (1) abdominal device/subcutaneous shock coil, (2) abdominal device/pleural shock coil, and (3) subcardiac device/pleural shock coil. RESULTS: During median follow-up of 5.2 (2.7-7.2) years, appropriate ICD discharges were documented in 12 (33.3%) and inappropriate shocks in 4 patients (11.1%). In 12/36 individuals (33.3%), a total of 25 surgical revisions were required due to NT-ICD malfunction. Eighteen out of 25 (72%) surgical revisions were necessary in patients with subcutaneous shock coil/abdominal device position. Surgical revisions (3/25, 12%) were significantly reduced (p < 0.001) after modifying the implantation technique to subcardiac device/pleural shock coil. CONCLUSIONS: NT-ICD was safe and effective in infants and young children. Appropriate ICD discharges occurred in a considerable number of patients. After modifying the implantation technique, the need for surgical revision could significantly be decreased.

Value of Regular Defibrillation Threshold Testing After Extracardiac Implantable Cardioverter Defibrillator Placement in Small Children During Mid-Term Follow-Up.

OBJECTIVES: The purpose of this study was to analyze course of defibrillation threshold (DFT) with growth. BACKGROUND: Data on regular DFT testing after extracardiac implantable cardioverter-defibrillator (ICD) placement in infants and small children is still limited. METHODS: An extracardiac ICD was placed in 23 pediatric patients (median age 6.1 years; median body weight 21 kg, median length 120 cm). The defibrillator lead was tunneled pleurally, and the device was placed as "active can" in the right upper abdomen or in a horizontal position between the diaphragm and the pericardium, respectively. DFT was verified intraoperatively, 3 months later, and every 12 months thereafter. The aim was to achieve DFT <15 J allowing ICD programming with a double safety margin above DFT. RESULTS: In all 23 patients, an intraoperative DFT <15 J could be accomplished. Serial DFT testing showed an increase from a median DFT of 10 J intraoperatively to 15 J after 1 year. During mean follow-up of 2.0 years, a significant correlation between DFT and body length, but not body weight, was observed. In 4 of 23 (17%) patients, surgical revision was required because of a DFT increase >20 J during regular DFT testing. No complications regarding DFT testing were noted. CONCLUSIONS: After extracardiac ICD placement in infants and small children, DFT increase related to body length was evident during mid-term follow-up. Routine serial DFT testing was a safe procedure and identified a significant DFT increase in 4 of 23 patients. Serial DFT testing during follow-up in these patients is recommended.

Heart Transplantation in a Toddler with Cardiac Kawasaki Disease.

Kawasaki disease is very rare in Western Europe. The disease may involve coronary arteries. A 2-year-old boy diagnosed with Kawasaki disease had had seizure-like symptoms. Further evaluation revealed recurrent myocardial ischemia and myocardial infarction. Due to extraordinary extension of the coronary disease, myocardial revascularization was not feasible and the toddler underwent successful heart transplantation after 97 days on waiting list.

Congenital coronary artery fistulas in adults: surgical treatment and outcome.

BACKGROUND: Congenital coronary artery fistulas, a subgroup of anomalies of the coronary arteries, are an extremely rare cardiac defect. Most patients are asymptomatic, and if symptoms are presented, they depend on the underlying anatomy. Knowledge of those fistulas is important for prognosis and management. METHODS: Thirteen adult patients with congenital coronary fistulas (8 male, 5 female) were operated in our department during the last decade (1990-1999). Mean age was 61.5+/-10.8 years. Diagnosis was made by coronary angiography, and 15 congenital coronary artery fistulas were found. RESULTS: All patients were symptomatic with clinical symptoms depending on the associated cardiac disorder. Coronary artery fistulas originated from the proximal left descending artery (n=10), left main stem (n=3), circumflex artery (n=1), right coronary artery (n=1), and drained into the main pulmonary artery (n=14) and left ventricle (n=1). Nine fistulas (60%) were interrupted on the outside of the heart, and six fistulas (40%) were closed through the opened pulmonary artery. There was no surgical death and no fistula-related complication. CONCLUSIONS: Surgical closure of congenital coronary artery fistulas in adults can be performed with a very low risk, and closure is recommended to prevent complications.

Beta-receptor downregulation in congenital heart disease: a risk factor for complications after surgical repair?

BACKGROUND: Neurohormonal activation in children with heart failure due to congenital heart disease leads to downregulation of myocardial beta-receptors that may influence the postoperative course after cardiothoracic surgery. METHODS: Myocardial biopsies of 26 children (aged 14+/-4 months) were obtained from the right atrium during cardiac surgery. Patients were allocated to either of two groups based on the duration of their intensive care unit stay: group 1 comprised those who stayed less than 7 days (n = 17), whereas group 2 comprised those who stayed more than 7 days, plus 3 infants who died during the early postoperative course (n = 9). For beta1- and beta2-mRNA quantitation, real-time polymerase chain reaction with fluorescence-labeled products was used. RESULTS: Values for myocardial beta1-receptor gene expression were twice as high in group 1 children compared with group 2 (beta1-receptor 0.12+/-0.07 versus 0.06+/-0.03, p = 0.0016; beta2-receptor 0.12+/-0.07 versus 0.06+/-0.03, p = 0.0071). Beta-receptor gene expression in 16 children who received standard treatment for heart failure averaged lower than in the 10 children who received additional propranolol. CONCLUSIONS: Beta-receptor downregulation due to congestive heart failure has an impact on the postoperative course in children with congenital disease and depends on heart failure therapy.

Orthotopic SCID mouse model with two newly established human lung squamous carcinoma cell lines.

The objective of this study was to present an orthotopic SCID mouse model using two newly established human cell lines derived from squamous cell carcinomas of the lung. GO-LCC1 cells (1 x 10(6)) and GO-LCC2 cells (3 x 10(6)) were implanted orthotopically into the right lungs of 10 C.B. 17 scid/scid mice. In both groups, aggressive tumor growth with partial infiltration of the thoracic wall, heart and diaphragm was observed. In only one case distant metastases in the contralateral lung were detected, while all animals developed tumors at the site of inoculation. Xenografted GO-LCC1 cells showed enhanced tumor propagation compared to GO-LCC2 cells. Our data underscore the usefulness of the SCID mouse model to study the biological behaviour of cultuved human tumor cells and furthemore demonstrate the clinical applicability of xenograft techniques using human tumor cell lines derived from pneumonectomy specimens of squamous lung carcinomas.

ICD therapy for primary prevention of sudden cardiac death after Mustard repair for d-transposition of the great arteries.

BACKGROUND: Years and decades after the Mustard atrial switch repair for d-Transposition of the great arteries, there is a subset of patients at increased risk for sudden cardiac death due to ventricular tachyarrhythmias. To date, little is known about indications, efficacy and benefit of internal cardioverter defibrillator (ICD) therapy indication in these patients. PATIENTS/METHODS: To characterize the Mustard patients already treated with an ICD, we conducted a single center case control study (n = 41). The charts of all patients after Mustard procedure at our institution were systematically reviewed for history, echocardiographic findings, arrhythmias, hemodynamics and medication as well as ICD discharges and complications. RESULTS: Significant differences between ICD (n = 12) and non-ICD patients (n = 29) were found regarding the stage of heart failure, need for heart failure medication, QRS duration and left ventricular diameter and performance. Inappropriate ICD discharges due to rapidly conducted atrial reentrant tachycardia and sensing failure were frequently observed. In 17 % of our Mustard patients with an ICD, infection of the implantation site required surgical revision. All ICD patients were of male gender. CONCLUSION: Patients after ICD implantation represent a subgroup among our Mustard patients with a more advanced state of cardiac disease. Not only systemic right ventricular diameter and performance but also subpulmonary left ventricular performance was an important factor predicting the long-term course of these patients. Prevention of inappropriate discharges requires decent device programming, close monitoring of lead integrity and treatment of atrial tachycardias.

Left cardiac sympathetic denervation for the management of life-threatening ventricular tachyarrhythmias in young patients with catecholaminergic polymorphic ventricular tachycardia and long QT syndrome.

BACKGROUND: Left cardiac sympathetic denervation (LCSD) may be a therapeutic adjunct for young patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) and long QT syndrome (LQTS) who are not fully protected by beta-blockade. OBJECTIVE: The objective of this analysis was to report our institutional experience with LSCD in young patients for the management of life-threatening ventricular arrhythmias in CPVT and LQTS. METHODS: Ten young patients with CPVT and LQTS underwent transaxillary LSCD at our institution. Mean age at surgery was 14.0 (range 3.9-42) years, mean body weight was 45.7 (range 15.5-90) kg. Five patients had the clinical diagnosis of CPVT, three were genotype positive for a mutation in the ryanodine-receptor-2-gene. Four of five LQTS patients were genotype positive. Indications for LCSD were recurrent syncope, symptomatic episodes of ventricular tachycardias and/or internal cardioverter-defibrillator (ICD) discharges, and aborted cardiac arrest despite high doses of beta-blockers. RESULTS: LCSD was performed via the transaxillary approach. No significant complications were observed. Two patients already had an ICD, 6 patients received an ICD at the same operation or shortly thereafter. Median length of follow-up after LCSD was 2.3 (range 0.6-3.9) years. After LCSD a marked reduction in arrhythmia burden and cardiac events was observed in all patients while medication was continued. None of the patients had any further ICD discharge for sustained VT. CONCLUSIONS: After LCSD, arrhythmia burden could significantly be reduced in all our young patients with CPVT and LQTS.

Midterm results after arterial switch operation for transposition of the great arteries: a single centre experience.

BACKGROUND: The arterial switch operation (ASO) has become the surgical approach of choice for d-transposition of the great arteries (d-TGA). There is, however an increased incidence of midterm and longterm adverse sequelae in some survivors. In order to evaluate operative risk and midterm outcome in this population, we reviewed patients who underwent ASO for TGA at our centre. METHODS: In this retrospective study 52 consecutive patients with TGA who underwent ASO between 04/1991 and 12/1999 were included. To analyze the predictors for mortality and adverse events (coronary stenoses, distortion of the pulmonary arteries, dilatation of the neoaortic root, and aortic regurgitation), a multivariate analysis was performed. The follow-up time was ranged from 1-10 years (mean 5 years, cumulative 260 patient-years). RESULTS: All over mortality rate was 15.4% and was only observed in the early postoperative period till 1994. The predictors for poor operative survival were low APGAR-score, older age at surgery, and necessity of associated surgical procedures. Late re-operations were necessary in 6 patients (13.6%) and included a pulmonary artery patch enlargement due to supravalvular stenosis (n = 3), coronary revascularisation due to coronary stenosis in a coronary anatomy type E, aortic valve replacement due to neoaortic valve regurgitation (n = 2), and patch-plasty of a pulmonary vein due to obstruction (n = 1). The dilatation of neoaortic root was not observed in the follow up. CONCLUSIONS: ASO remains the procedure of choice for TGA with acceptable early and late outcome in terms of overall survival and freedom of reoperation. Although ASO is often complex and may be associated with morbidity, most patients survived without major complications even in a small centre.

Immunohistochemical characterization of neotissues and tissue reactions to septal defect-occlusion devices.

BACKGROUND: We sought to evaluate tissue reactions within and at the surface of devices for interventional therapy of septal defects and to identify antigen characteristics of neotissues. METHODS AND RESULTS: Atrial or ventricular septal defect-occlusion devices (Amplatzer, n=7; Cardioseal/Starflex, n=3) were processed using a uniform protocol after surgical removal from humans (implantation time, 5 days to 4 years). Devices were fixed in formalin and embedded in methylmethacrylate. Serial sections were obtained by sectioning with a diamond cutter and grinding, thus saving the metal/tissue interface for histologic evaluation. Immunohistochemical staining was performed using conventional protocols. Superficial endothelial cells stained positive for von Willebrand factor. Within the newly formed tissues, fibroblast-like cells were identified with a time-dependent expression of smooth muscle cell maturation markers (smooth muscle actin, smooth muscle myosin, h-caldesmon, and desmin) beside extracellular matrix components. Neovascularization of the newly formed tissues was demonstrated with the typical immunohistochemical pattern of capillaries and small vessels. Inflammatory cells could be identified as macrophages (CD68+) and both T-type and B-type lymphocytes (CD3+, CD79+). CONCLUSIONS: This is the first presentation of results from serial immunohistochemical staining of a collection of explanted human septal-occlusion devices. A time-dependent maturation pattern of the fibroblast-like cells in the neotissues around the implants could be described. Neoendothelialization was seen in all specimens with implantation times of 10 weeks or more. The time course of neoendothelialization, as seen in our study, further supports the clinical practice of anticoagulant or antiplatelet therapy for 6 months after implantation. This time interval should be sufficient to prevent thromboembolic events due to thrombus formation at the foreign surface of cardiovascular implants.