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We report our experience in pediatric patients supported by extracorporeal membrane oxygenation (ECMO) for perioperative circulatory failure from January 1987 to June 2005. Pediatric patients (n = 110) who had ECMO support for congenital heart defects, myocarditis, and cardiomyopathy (age range, newborn to 18 years; weight range, 2.3-69 kg) were included and divided into three groups based on timing of ECMO support. EMCO support was used preoperatively in 21 patients (19.1%) (mean age, 4 years +/- 8 months; mean weight, 23.7 +/- 8.9 kg). Duration of ECMO support was 8.3 +/- 7 days. Fifty-six patients (56.56%) (mean age, 5.11 +/- 5 years; mean weight, 15.7 +/- 6.9 kg) had intraoperative ECMO support for myocardial insufficiency, low output syndrome, right ventricular failure, left ventricular failure, malignant arrhythmia, pulmonary hypertension, and repeated resuscitation. Mean duration of ECMO support was 4.98 +/- 1 days. Postoperative ECMO support was used in 29 patients (mean age, 7.5 +/- 1 years; mean weight, 23.4 +/- 6.4 kg). Mean duration of ECMO was 4.6 +/- 1 days. Mean postoperative day of ECMO institution was 40.4 +/- 2 days. Our experience shows that ECMO support can be offered perioperatively to any patient with potentially reversible pulmonary, cardiac, or cardiopulmonary failure, excluding those whose outcome is inevitable.

Background: Pediatric size pneumatically driven extracorporeal ventricular assist devices (VAD) for infants and small children were introduced into clinical routine in 1992. In the initial period, the results in infants were poor. Since then, several improvements have been introduced with regard to the cannulas, connectors, heparin coating of the blood pump inner surface, anticoagulant treatment and coagulation monitoring, and earlier decision-making in favor of pump implantation before irreversible shock has set in., Methods: Since 1990 and as of January 1, 2005, 62 Berlin Heart Excor systems have been implanted in patients below 18 years of age at our institution. The patients were divided into two groups according to the period of treatment: period 1, devices implanted between 1990 and 1998 (n = 34), and period 2, devices implanted between 1999 and 2004 (n = 28). We compared our experience during the earlier and later periods., Results: There were no significant differences in the preoperative patient data between the two periods except for time of support (17.9 +/- 27.7 days versus 53.2 +/- 83.9 days, p = 0.001). In period 1, more patients needed a biventricular VAD whereas in period 2, more patients were effectively treated with a left VAD (p = 0.05). In the later period, the chest could be primarily closed in a significantly higher percentage of infants (0% versus 89%, p = 0.012), and more infants could be extubated on the VAD (0% versus 55%, p = 0.16). Discharge from the hospital after either weaning from the system or heart transplantation was achieved for 35% in period 1 and for 68% in period 2 (p = 0.029). Whereas in period 1 there were no survivors in the group of children younger than 1 year old, during period 2, survival in this age group was similar to that of the two groups of older children (p = 0.024). There was a significant improvement in the discharge rate in period 2 in patients with cardiomyopathy (43% versus 76%, p = 0.045) and postcardiotomy heart failure (0% versus 57%, p = 0.01)., Conclusions: Earlier implantation of VADs, heparin coating of the blood pumps, and substantial modifications in cannula design, anticoagulation, and the coagulation monitoring regimen have led to a significant increase in the survival and discharge rate, especially among children under 1 year of age. The pediatric size Berlin Heart Excor VAD is a valuable option as a bridge to heart transplantation or recovery for children suffering from cardiogenic shock.

Within the last 16 years, the Berlin Heart EXCOR systems have been used for circulatory support in 73 infants and children up to 17 years of age (mean, 7 years) with severe circulatory failure resistant to pharmacological therapy at our institution. These were patients with cardiomyopathy, fulminant myocarditis, end-stage congenital cardiac defects, and acute heart failure after congenital heart surgery. Mean EXCOR support time was 36 days (range, 1 to 420 days). Forty-four patients (62%) survived up to transplantation or after weaning and 37 (51%) of them, including 9 infants, were discharged home. These results in patients with very advanced disease have improved significantly during the past few years as the result of technical developments and growing experience in the treatment of patients on the device and in postoperative care. The following article gives answers to five questions frequently asked about intensive care unit treatment while on the device, anticoagulation and additional medical support during left ventricular or biventricular support, the daily treatment of the children, and options for the weaning procedure.

Objective: We examined the clinical impact of diaphragmatic palsy (DP) as a result of phrenic nerve injury following cardiothoracic surgery, specifically its effects on morbidity and mortality, early regeneration capacity of the phrenic nerve, and role of surgical diaphragmatic plication., Methods: A retrospective case control study was performed in 74 children with DP and 74 matched controls after cardiothoracic surgery within the past 14 years., Results: Following 5,128 surgical procedures in children (aged under 18 years) we found an incidence of DP of 1.4%. There were no differences in mortality between the groups, and the cause of death was not related to DP or plication in any of the patients. However, patients with diaphragm impairment had significantly longer duration of mechanical ventilation (median 3 days vs. 1), ICU stay (7 days vs. 3.5), duration of hospital stay (16 days vs. 12), and for antibiotic treatment (16 days vs. 7). Because of prolonged respiratory problems 40 children (54%) underwent surgical diaphragmatic plication to flatten the diaphragm in its inspiratory position. In children with DP younger age was a strong predictor for plication (median 3.8 months vs. 12.1)., Conclusions: Especially in newborns and young infants with DP the length of mechanical ventilation, ICU stay, and hospital stay are prolonged. Early spontaneous recovery of the phrenic nerve is rare. In cases of respiratory impairment early transthoracic diaphragmatic plication is an effective means of treatment.

Sildenafil (Viagra) has been shown to be an effective pulmonary vasodilator and is increasingly used in patients with pulmonary hypertension. Its effects on the cerebral circulation are unclear and have not yet been described. We investigated the effect of i.v. sildenafil treatment on cerebral oxygenation in 13 children with elevated pulmonary vascular resistance due to congenital heart defects after cardiac surgery using near-infrared spectroscopy (NIRS). Median age was 4.5 mo, and median weight was 5.5 +/- 1.8 kg. Sildenafil was administered in three steps of 15 min each with cumulative doses of 0.025, 0.1, and 0.25 mg/kg. We examined the changes of oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), total hemoglobin (tHb) concentration, cytochrome oxidase (CytOx) oxygenation, and cerebral tissue oxygenation index (TOI) in 13 children. A significant increase in cerebral HbO2 and tHb at the beginning of i.v. sildenafil administration with a decrease in HHb was observed. These changes led to a significant elevation in cerebral TOI from 63.4 +/- 2.5% to 65.7 +/- 2.8%, whereas mean systemic arterial pressure and arterial oxygen partial pressure tended to decrease. In conclusion, we observed a reversible increase of HbO2, tHb, and hemoglobin oxygen saturation in the scanned tissue section after i.v. sildenafil administration. These findings may be clinically relevant because they indicate that after cardiac surgery, sildenafil may increase cerebral blood flow (CBF), probably due to general endothelial dysfunction after cardiopulmonary bypass (CPB).

The pediatric-size pneumatically driven pulsatile extracorporeal ventricular assist device (VAD) Berlin Heart EXCOR (Berlin Heart Mediprodukt GmbH, Berlin, Germany) was introduced into clinical practice by the German Heart Institute Berlin in 1992. Until July 1, 2005, Berlin Heart EXCOR systems have been used for circulatory support in 68 children up to 18 years of age with severe circulatory failure resistant to pharmacologic therapy. These were patients suffering from cardiomyopathy, fulminant myocarditis, end-stage congenital cardiac defects, and acute heart failure following congenital heart surgery. Mean VAD support time was 35 days (range, 0 to 420 days). Forty-two patients (62%) survived to transplantation or after weaning; 37 patients (54%), including eight infants, were discharged home. These results in patients with very advanced disease have improved significantly in recent years because of technical developments and growing experience in the treatment of patients on the device, in postoperative care and optimal timing for VAD implantation. Timely implantation of the Berlin Heart EXCOR in the course of progressive heart failure now appears to be justified because the system has undergone the necessary modifications and the accumulation of clinical knowledge has made its use highly reliable and safe.

Background: One approach to tissue engineering has been the development of in vitro conditions for the fabrication of functional cardiovascular structures intended for implantation. In this experiment, we developed a pulsatile flow system that provides biochemical and biomechanical signals in order to regulate autologous, human patch-tissue development in vitro., Methods: We constructed a biodegradable patch scaffold from porous poly-4-hydroxy-butyrate (P4HB; pore size 80 to 150 microm). The scaffold was seeded with pediatric aortic cells. The cell-seeded patch constructs were placed in a self-developed bioreactor for 7 days to observe potential tissue formation under dynamic cell culture conditions. As a control, cell-seeded scaffolds were not conditioned in the bioreactor system. After maturation in vitro, the analysis of the tissue engineered constructs included biochemical, biomechanical, morphologic, and immunohistochemical examination., Results: Macroscopically, all tissue engineered constructs were covered by cells. After conditioning in the bioreactor, the cells were mostly viable, had grown into the pores, and had formed tissue on the patch construct. Electron microscopy showed confluent smooth surfaces. Additionally, we demonstrated the capacity to generate collagen and elastin under in vitro pulsatile flow conditions in biochemical examination. Biomechanical testing showed mechanical properties of the tissue engineered human patch tissue without any statistical differences in strength or resistance to stretch between the static controls and the conditioned patches. Immunohistochemical examination stained positive for alpha smooth muscle actin, collagen type I, and fibronectin. There was minor tissue formation in the nonconditioned control samples., Conclusions: Porous P4HB may be used to fabricate a biodegradable patch scaffold. Human vascular cells attached themselves to the polymeric scaffold, and extracellular matrix formation was induced under controlled biomechanical and biodynamic stimuli in a self-developed pulsatile bioreactor system.

Objective: Although considerable progress has been made on ventricular assist devices (VAD) for adults, pneumatic pulsatile circulatory support in young infants is still limited. There is a need for long-term ventricular assist devices to bridge the failing myocardium of young children until recovery or transplantation. Miniaturized devices and innovative modalities need to be optimized. We report on our experience., Methods: From 1/1992 to 6/2004, 18 infants (6 male/12 female) under 1 year of age were treated with the Berlin Heart Excor VAD. The infants were divided into two groups, depending on the year of treatment. Group A consists of eight infants resuscitated and supported with a pulsatile pneumatic ventricular assist device between 1992 and 1998 and group B consists of 10 infants treated between 1999 and 6/2004. With the pediatric-sized Berlin Heart we used miniaturized extracorporeal pneumatically driven blood pumps, the lowest stroke volume being 10 ml., Results: In 18 children, age 3-345 (median 147) days, artificial replacement of heart function was applied for long-term support (1-64, median 10 days) as a life-saving measure in our hospital. Nine had LVAD and nine BVAD support. All were in cardiogenic shock with multiorgan failure; three had fulminant myocarditis, four cardiomyopathy, and one chronic stage of congenital heart disease. Five children were weaned from the system, three reached heart transplantation, and 10 died on the VAD. There were no differences between groups A and B regarding age, body weight or diagnosis, but the duration of mechanical support differed: Group A, median 2, range 1-16 days; group B, median 12, range 1-100 days. Since 1999 (group B), the survival rate of our small infants has increased to 70% whereas none of the infants in group A survived to be discharged., Conclusions: The outcome of VAD support in small infants is no longer inferior to that of adult support, now optimized cannulas, modified anticoagulation and optimized surgical and intensive care management have been established.

Objective: Excess pulmonary to systemic blood flow ratio (Qp/Qs) correlates with hemodynamic instability and mortality after modified Norwood operation. Studies suggest that maximal oxygen delivery occurs at a Qp/Qs of around 1. The use of a rather small modified Blalock-Taussig shunt (MBTS) is believed to achieve this goal. However, optimal MBTS size with respect to postoperative hemodynamics remains unclear., Methods: Between 2/2002 and 2/2004, 20 consecutive patients underwent Norwood operation; there were 19 operative survivors: nine with a normalized MBTS area (NSA) > or = 3.3 mm2/kg (group 1) and 10 with NSA < 3.3 mm2/kg (group 2). Mean arterial pressure (MAP) and common atrial pressures (CAP), arterial and superior vena cava oxygen saturations, urinary output and inotropes recorded for the postoperative hours 0, 6, 12, 18, 24 and 48 were analyzed., Results: Hospital mortality was 11.1% (1/9) in group 1 and 30% (3/10) in group 2 (P = 0.6). For group 1 significantly higher MAP of 52+/-1.3 versus 46+/-0.8 mmHg (P < 0.001), higher urinary output of 6.2+/-0.5 versus 4.2+/-0.5 ml/kg per h (P < 0.01), lower CAP of 8+/-0.3 versus 10+/-0.4 mmHg (P < 0.001), and lower heart rate of 145+/-2.6 versus 160+/-1.6 bpm were recorded than for group 2. In group 1, lower doses of adrenaline (0.03+/-0.01 versus 0.15+/-0.01 microg/kg per min, P < 0.05) and noradrenaline (0.01+/-0.01 versus 0.13+/-0.04 microg/kg per min, P < 0.01) were needed. Although Qp/Qs was more often calculated to be > 1.5 in group 1 (51 versus 31%), arteriovenous oxygen difference and oxygen excess factor were not significantly different, indicating similar oxygen delivery., Conclusions: Monitoring of the central venous oxygen saturations and application of afterload reduction in cases of high Qp/Qs allows the insertion of a larger MBTS without association with lower oxygen delivery. In fact, better hemodynamic status with less inotropic support was noted with a larger MBTS early after Norwood operation.

Particularly in neonates, complex cardiac surgery employing cardiopulmonary bypass normally requires the transfusion of autologous blood components. This is predominately caused by the relatively high priming volume of the circuit with subsequent extreme hemodilution. We report on a synoptic approach to avoiding transfusions in a 2.2 kg neonate with scheduled for correction of an intracardiac total anomalous pulmonary venous connection to the coronary sinus and a persistent foramen ovale. In this patient with a preoperative hemoglobin value of 16.5 g/dL, minimization of the cardiopulmonary bypass circuit, adjustment of the perfusion technique and strict reduction of blood sampling resulted in complete avoidance of transfusions during the entire course of the operation while maintaining safe hemoglobin levels, which never fell below a concentration of 8 g/mL.

Objective: Different mechanical circulatory support (MCS) systems are used in children with intractable heart failure. However, the need for anticoagulation leads to hemorrhage with subsequent use of blood products. We compared the coagulation disorders and the need for blood products in children treated either with extracorporeal membrane oxygenation (ECMO) or with the Berlin Heart pulsatile pneumatic ventricular assist device., Patients: We retrospectively reviewed the first 8-day course of 64 children who were on MCS for more than 2 days between 1990 and 2002. Thirty children (median age 7.4 years, weight 25.5 kg) received Berlin Heart support and 34 children (median age 1.8 years, weight 9.2 kg) ECMO. Anticoagulation was accomplished by continuous infusion of heparin. Red blood cell count, platelet count, aPTT, AT III, fibrinogen, and ACT were measured regularly. Depending on blood loss and the coagulation disorder, red blood cells, fresh frozen plasma, platelets, and AT III were substituted., Results: There were no preoperative differences in hematological parameters between the two groups. In the Berlin Heart group platelet transfusion was 4.3 ml x kg x day vs 24.6 ml x kg x day in the ECMO group. Red blood cell substitution was 17.2 vs 60.3 ml.kg.day. Fresh frozen plasma substitution was 8.5 ml x kg x day vs 46.9 ml x kg x day (P<0.001). Even in the congenital heart defect subgroups, when MCS was implanted without recent cardiotomy, the differences were significant. Nevertheless, the mean daily values for hemoglobin, platelets, and fibrinogen were lower in the ECMO group. There was lower overall mortality in the Berlin Heart group., Conclusions: Compared to ECMO, use of the Berlin Heart in children results in less blood loss and lower consumption of red blood cells, platelets, and fresh frozen plasma.

Optimal in vitro conditions are necessary for the development of a strong, well structured, and functional tissue engineered cardiovascular structure eventually designed for implantation. To further optimize in vitro conditions for cell proliferation and extracellular matrix formation in tissue engineering of cardiovascular structures, in this study, ascorbic acid and growth factors as additives to standard cell culture medium were evaluated for their effect on tissue development in vitro. Biodegradable polymer patches [polyglycolic acid (PGA) coated with poly-4-hydroxybutyrate (P4HB)] were seeded with human pediatric aortic cells and cultured for 7 and 28 days. Group A was cultured with standard medium (DMEM with 10% fetal calf serum and 1% antibiotics) supplemented with ascorbic acid; group B was cultured with standard medium plus ascorbic acid and basic fibroblast growth factor (bFGF); group C was cultured with standard medium adding ascorbic acid and transforming growth factor (TGF). Analysis of the cell seeded polymer constructs included DNA assay, collagen assay, and histologic and immunohistochemical examination for cell proliferation and collagen formation. After 7 and 28 days of culture, group B and group C showed a significantly higher DNA content compared with group A. The addition of bFGF (group B) led to a markedly higher collagen synthesis after 28 days of culture compared with the additives in groups C and A. The histologic and immunohistochemical examination also revealed a more dense, organized tissue development with pronounced matrix protein formation in the tissue engineered structures in group B after 28 days of culture. When seeded on to the polymeric scaffold, human vascular cells proliferate and form organized cell tissue after 28 days of culture. The addition of bFGF and ascorbic acid to the standard medium enhances cell proliferation and collagen synthesis on the biodegradable polymer, which leads to the formation of more mature, well organized tissue engineered structures.

Over recent years, increasing awareness has been aroused to the hazards of the utilization of donor blood products. Particularly in neonate cardiac surgery employing cardiopulmonary bypass (CPB), the relative high priming volume of the CPB system and its adjunctive components, such as hemofilters, causes severe hemodilution and, therefore, particularly during extended perfusions, customarily requires priming of the system with autologous blood components. We report on our efforts to minimize the CPB system and adjust the perfusion strategy to the goal of transfusion-free CPB in a 3.7 kg neonate scheduled for repair of transposition of the great arteries.

Purpose: This study was undertaken to evaluate the antiadhesive properties of a polymeric agent in infants undergoing staged surgical correction of congenital heart abnormalities., Description: Sixteen infants having staged surgical repair were treated with a polymeric matrix at the completion of the initial surgery. There were 5 untreated controls. The tenacity and extent of adhesions at five separate regions of the heart were evaluated at the follow-up surgery., Evaluation: For all sites combined, there was a threefold difference in median tenacity scores in favor of the experimental treatment (1.0 vs 3.0, p < 0.01). Significant differences were achieved separately at the right ventricle and the anterior surface of the great vessels (p = 0.02 for both comparisons). Analysis of adhesion scores reflecting the extent of adhesions similarly favored the experimental treatment for all sites (80 vs 270, p < 0.01), with significant differences persisting at the right atrium (p < 0.01) and the anterior surface of the great vessels (p = 0.04). There were no treatment-related adverse events., Conclusions: Use of this polymeric agent at the completion of open cardiac surgery may prevent the occurrence or reduce the severity of pericardial adhesions.

Background: Increased pulmonary vascular resistance (PVR) because of congenital heart disease (CHD) may be caused by a dysfunction in endogenous pulmonary endothelial nitric oxide (NO) production. In other forms of pulmonary vascular disease with increased PVR, an elevated activity of a phosphodiesterase type 5 (PDE-5), responsible for the degradation of cyclic guanidine monophosphate (cGMP), the second messenger of endothelially produced NO, has been demonstrated. This study compares the effects of inhaled NO before and after the specific inhibition of the PDE-5 by intravenous sildenafil (Viagra) in pre- and postoperative children with increased PVR because of CHD., Methods and Results: 12 children with congenital heart disease (age 0.2 to 15.7 years, median 2.4 years) and increased mean pulmonary arterial pressure, and 12 postoperative children (age 0.11 to 0.65 years, median 0.32 years) with increased PVR (8.3+/-1.0 Wood Units*m2) were studied during cardiac catheterization ("cath laboratory"), or within 2 hours after return from cardiac surgery ("post op"), respectively. All were sedated, tracheally intubated and paralyzed. During alveolar hyperoxygenation (FiO2=0.65), the effects of inhaled NO (20 ppm) were compared before and after the stepwise infusion of sildenafil ("cath laboratory", 1 mg/kg; post op, 0.25 mg/kg). Intravenous sildenafil more effectively reduced PVR than NO (11.5% versus 4.3% in the "cath laboratory" patient group, P<0.05, and 25.8% versus 14.6% in the post op patient group, P=0.09. The increase in cGMP in response to NO was potentiated (2- to 2.4-fold) by PDE-5 inhibition. While the vasodilating effects of sildenafil showed pulmonary selectivity, its infusion was associated with increased intrapulmonary shunting in the postoperative patients (Qs/Qt=16.5+/-4.7% to 25.5+/-18.2% P=0.04)., Conclusions: Intravenous sildenafil is as effective as inhaled NO as a pulmonary vasodilator in children with congenital heart disease. Although clinically insignificant in this study, increased intrapulmonary shunting with sildenafil may be disadvantageous in some patients after CHD surgery.