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This article introduces a new Hopenhayn-Melitz-type model of heterogeneous producers with endogenous technology choice. Different from previous trade models, it describes smallholder producers in rural areas of developing countries in the context of environment and development economics. Shocks (climate change) and various policies affect the producers’ endogenous choice between market entry or exit and between simple or advanced technology. This adds new margins of adjustment to models used in this context. Based on these mechanisms, the theoretical analysis identifies a novel type of the rebound effect via market entry. The numerical application to coffee production in rural Vietnam shows that secondary effects of the shocks, such as changes in the number of producers, can be larger than the original impact. Technology-supporting policies can have unintended detrimental side effects on less productive producers.

Both single- and double-outflow cavopulmonary assist devices (CPADs) were recently proposed for the Fontan population, whereas single-outflow configurations were evaluated in large animal trials and double-outflow concepts are lacking an equivalent in vivoassessment. The aim of this study was to test the hemodynamic properties of a double-outflow CPAD device in an acute sheep model. The two inflow cannulae of a CPAD were anastomosed to the caval veins. Outflow graft connection was performed via end-to-side anastomosis to the right (RPA) and main pulmonary artery (MPA). Speed ramp protocols were conducted, and hemodynamic effects were monitored in terms of caval flows, cardiac output (CO), central venous pressure (CVP), pulmonary artery pressure (PAP), and left atrial pressure (LAP). Six experiments were conducted (53.35 ± 5.1 kg). In three experiments, the animal model was established, the CPAD was examined, and restoration of biventricular equivalency in terms of venous return was achieved. Venous pressures (CVP) declined linearly with increasing pump speed (r > 0.879), whereas caval flow (r > 0.973), CO (r > 0.993), PAP (r > 0.973), and LAP (r > 0.408) increased. Despite the considerable complexity of the sheep model caused by the sheep pulmonary arterial anatomy that requires substantial graft bending, the CPAD was evaluated in three acute experiments and showed the potential to completely substitute a subpulmonary ventricle.

Atrial septal defects (ASDs) encounter for 10–15% of congenital heart defects [1].

We describe the experience with biventricular HeartWare VAD (HVAD) support in the pediatric population. As of May 2017, using the Heartware database, 11 centers were identified. Seven centers participated providing information for 10 patients (four females, six males). Median age at the time of implantation was 12.7 ± 4.6years (5.3–6.9), median body surface area was 1.56. The indications for biventricular assist device (BiVAD) support included: myocarditis (n = 1), cardiomyopathy (n = 8), and one posttransplant heart failure. Six patients had a primary BiVAD implantation. Out of 10 patients with BiVAD, five were transplanted, one is ongoing (postoperatively day 207), and none were weaned from the device. Two patients (20%) were discharged from hospital on BiVAD support. Median support time was 52 days (16–235). The overall success rate was 60% surviving to transplant (median support time: 51 days) or are ongoing. Reasons for death included bleeding (n = 2), intracerebral hemorrhage (n = 1), and multisystem organ failure (n = 1). Eight out of 10 patients had at least one major complication, that is, major bleeding requiring re-operation (n = 6), severe neurologic injury (n = 1), and pump thrombosis in two patients requiring device exchange (n = 1) or thrombolysis therapy (n = 1). BiVAD HVAD implantation in children is a rare procedure, with high mortality and low discharge rates. Bleeding requiring re-operation was the most common postoperative complication, despite fresh sternotomies in the majority of patients. The risk and benefit ratio of such an approach should be carefully reviewed, and compared with the standard strategy using the Berlin EXCOR.

Background: Long-term survival of patients with a single ventricle palliated with a Fontan procedure is still limited. No curative treatment options are available. To investigate the pathophysiology and potential treatment options, such as mechanical circulatory support (MCS), appropriate large animal models are required. The aim of this review was to analyze all full-text manuscripts presenting approaches for an extracardiac total cavopulmonary connection (TCPC) animal model to identify the feasibility and limitations in the acute and chronic setting.Methods: A literature search was performed for full-text publications presenting large animal models with extracardiac TCPCs on Pubmed and Embase. Out of 454 reviewed papers, 23 manuscripts fulfilled the inclusion criteria. Surgical procedures were categorized and hemodynamic changes at the transition from the biventricular to the univentricular condition analyzed.Results: Surgical procedures varied especially regarding coronary venous flow handling and anatomic shape of the TCPC. In most studies (n = 14), the main pulmonary artery was clamped and the coronary venous flow redirected by additional surgical interventions. Only in five reports, the caval veins were connected to the right pulmonary artery to create a true TCPC shape, whereas in all others (n = 18), the veins were connected to the main pulmonary artery. An elevated pulmonary vascular resistance was identified as a limiting hemodynamic factor for TCPC completion in healthy animals.Conclusions: A variety of acute TCPC animal models were successfully established with and without MCS, reflecting the most important hemodynamic features of a Fontan circulation; however, chronic animal models were not reported.

Coronary artery anomalies are a diverse group of disorders with highly variable manifestations and pathophysiological mechanisms. The origin of a single coronary artery from an atretic pulmonary trunk is a rare anomaly. We encountered this in an 8-day-old female newborn. This report should alert the cardiac surgical community to this fatal coronary malformation. Surgeons should bear this anomaly in mind when they face unusual myocardial behavior intraoperatively.

Purpose: Rotary blood pumps are a promising treatment approach for patients with a total cavopulmonary connection and a failing cardiovascular system. The aim of this study was to investigate the hemodynamic effects of cavopulmonary support using a numerical model with closed-loop baroreflex and exercise mechanisms.Methods: A numerical model of the univentricular cardiovascular system was developed, mimicking the hemodynamics during rest and exercise. Rotary blood pumps with different hydraulic pump characteristics (flat vs steep pressure-flow relationships) were investigated in the cavopulmonary position. Furthermore, two support modes—a constant speed setting and a physiologically controlled speed—were examined.Results: Hemodynamics without rotary blood pumps were achieved with less than 10% deviation from reported values during rest and exercise. Rotary blood pumps at constant speed improve the hemodynamics at rest, however, they constitute a hydraulic resistance during light (steep characteristics) or moderate (flat characteristics) exercise. In contrast, physiologic control increases cardiac output (moderate exercise: 8.2 vs 7.4 L/min) and reduces sympathetic activation (heart rate at moderate exercise: 111 vs 123 bpm).Conclusion: In this simulation study, the necessity of an automatically controlled rotary blood pump in the cavopulmonary position was shown. A pump at constant speed might constitute an additional resistance to venous return during physical activity. Therefore, a physiologic control algorithm based on the pressure difference between the caval veins and the atrial pressure is proposed to improve hemodynamics, especially during physical activity.

The Ross operation is the operation of choice for children and young adults who require aortic valve replacement. Although the allograft does not require anticoagulation and has a superior hemodynamic profile compared to other valve substitutes, concerns regarding allograft and autograft longevity have risen in the last decade. We present a case illustrating an alternative operative technique for patients with failed Ross procedure in which the autograft is recycled in order to avoid a two-allograft replacement.

Background: The Ross operation provides the advantage of growth potential of the pulmonary autograft in the aortic position. However, development of autograft dilatation and regurgitation may occur. We sought to assess the progression of autograft diameters and aortic regurgitation (AR) with regard to patient age at the time of the Ross operation.Methods: Autograft echo dimensions from 48 children <16 years of age at the time of the Ross operation, who had follow-up echocardiograms at <20 years of age, were analyzed using hierarchical multilevel modeling. The zvalues of autograft dimensions were calculated according to the normal aortic dimensions. Mean follow-up was 5.1 ± 3.3 years. The mean age at the time of the Ross operation was 10.0 ± 4.3 years.Results: The mean zvalues of all patients showed a significant increase with follow-up time at the sinus (0.5 ± 0.1/year, P< .001) and the sinotubular junction (0.7 ± 0.2/year, P < .001) but not at the annulus (0.1 ± 0.1/year, P = .59). There was no significant difference in the zvalues of sinus and the sinotubular junction between younger and older children at implantation and with time. The initial annulus zvalue was significantly larger in younger children (P < .0001), whereas the annual increase was significantly higher in older children (P = .021). Age at operation has no impact on the initial AR grade (P = .60). The AR tends to increase more quickly in older patients (P = .040). Sinus and sinotubular junction dilate with time, regardless of patient age.Conclusions: Young children show larger initial annulus sizes than older children. However, annulus diameters tend to normalize in young children, whereas they increase in older children. Autograft regurgitation develops slowly, but significantly, and predominantly in older children. Stabilizing measures to prevent autograft root dilatation are warranted in adolescents, but they are not required in young children.

Introduction: Aortic valve regurgitation or the presence of a mechanical aortic valve prosthesis is a relative contraindication for implantation of left ventricular assist devices (LVAD). However, concomitant aortic valve replacement by a biological prosthesis is one of the options in this situation. We analyzed our recent experience with left ventricular assist device implantation and concomitant aortic valve replacement.Methods: Between January 1, 2008 and January 15, 2012, 318 adult patients (>18 years old) were supported with a long-term implantable LVAD in our institution. In 19, simultaneous aortic valve replacement (6 redo and 13 primary procedures) was performed. Patients were divided into 2 groups according to INTERMACS (IM) level: Group 1 (n = 7) consisted of patients with IM level 1–2 and Group 2 (n = 12) of IM level 3–4 patients. As a control cohort we analyzed all LVAD recipients during the study period (n = 299, study group excluded). The control cohort was similarly divided into two groups according to the IM level: Group 3 (n = 162) consisted of patients with IM level 1–2 and Group 4 (n = 137) of those with IM level 3–5. Perioperative data and outcomes in all groups were retrospectively analyzed and compared (Group 1 compared to Group 3; and Group 2 to Group 4).Results: In study Groups 1 and 2 all patients were male; in Groups 3 and 4, 80% and 88% respectively were male. Median age distribution in Groups was 55, 61, 54, and 57 years respectively. Patients from Group 2 were significantly older than those from Group 4 (p = 0.039). Body mass index was significantly lower in Group 1 than in Group 3 (p = 0.033). Cardio-pulmonary bypass time was significantly longer in Groups 1 and 2 compared with Groups 3 and 4 respectively (p=0.001). Patients from Group 1 had a trend more often to develop right ventricular failure requiring a right ventricular assist device (RVAD) than those in Group 3 (p = 0.09). Intensive care unit stay duration of mechanical ventilation and in-hospital mortality in Group 1 were significantly higher than in Group 3 (p = 0.025, p = 0.005, p = 0.038). Patients from Group 2 had similar outcomes compared to those from Group 4.Conclusions: In stable patients, simultaneous aortic valve replacement and LVAD implantation are not associated with an impaired outcome. In patients with cardiogenic shock an additional aortic valve replacement may impair outcome; therefore alternative techniques should be considered.

Purpose The pediatric population has benefited greatly by the evolution of ventricular assist devices (VADs) leading to miniaturization. Device design like the HeartWare® VAD allows for implantation in smaller patients or even as an implantable biventricular assist device.Case report A ten-year-old female patient (body surface area: 1.02 m2, 27 kg) waiting for 7 months for heart transplantation was admitted to the intensive care unit due to terminal heart failure. Transthoracal echocardiography revealed heart failure with an estimated ejection fraction of 15%, dilated left ventricle, moderate tricuspid and mitral regurgitation. Despite maximal medical therapy (including milrinone and 1 course of Levosimendan intravenous), her condition further worsened and mechanical circulatory support was indicated. After implantation of a HeartWare HVAD® device as an LVAD, a second pump was implanted as a right VAD (RVAD). The sewing ring of the HVAD was attached to the lateral wall of the right atrium. The device was implanted so that the axis of the inflow cannula was pointing towards the tricuspid valve. The outflow graft was anastomosed to the pulmonary artery truncus; the outflow graft diameter was not narrowed. Anticoagulation with IV heparin was started 8 hours postoperatively with a target antifactor Xa level of 0.3 to 0.6 IU/ml. The patient was extubated after 26 hours and fully mobilized. BVAD settings were: 2,300 revolutions per minute, calculated flow: 3.2 liters per minute and 2.7 W for the left side and 2,080 revolutions per minute, calculated flow: 3.3 L per minute and 2.1 W for the right side.

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.

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 HbO2and 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).

AbstractThe aim of this study was to evaluate the relationship between the kinetic patterns of the protein S-100β an astroglial cell marker, and its immunohistochemical expression in the brain in rabbits that underwent cardiopulmonary bypass with deep hypothermic circulatory arrest.Fourteen New Zealand rabbits (weight, 3.1±0.25 kg) were anaesthetised, intubated and mechanically ventilated. Four animals were not connected to the cardiopulmonary bypass and served as controls. Ten animals were perfused according to a uniform protocol. After systemic cooling, deep hypothermic circulatory arrest was induced for 60 minutes. After reperfusion and rewarming, the animals were weaned from bypass and sacrificed. In the brain, astrocyte reactivity for S-100β was evaluated immunocytochemically (DPC®Immustain) and the serum concentrations of S-100β were analysed using a commercially available immunoluminometric kit (Byk-Sangtec®, Dietzenbach, Germany).In all experimental animals a significant increase of the serum concentration of the protein S-100β was found immediately after reperfusion and the termination of cardiopulmonary bypass. In comparison with the control animals, increased staining of S-100β was found in the astroglial cells and swollen astrocytic end-feet in the perivascular regions. There were fewer signs of neuronal cell injury of neurones in the hippocampus structure.In conclusion, astrocytic activation and S-100β over-expression seems to precede the neurodegeneration following deep hypothermic circulatory arrest. The marked perivascular cell swelling may support the assumption of reperfusion injury of the astroglial cell complex that forms the blood-brain barrier, which may be indicative of the source of the released S-100β into the blood stream.

Introduction Miniaturization and surgical progress in the field of ventricular assist device (VAD) therapy will lead to an increasing use in grown-up patients with congenital heart disease (GUCH). VAD implantation in such patients, especially biventricular VAD (BVAD) placement, can be very challenging, potentially associated with high morbidity and mortality.Methods and Results We report on a 47-year-old male patient in terminal biventricular failure with pulmonary hypertension 40 years after a Mustard procedure. The patient was successfully provided with a HVAD (HeartWare; HeartWare Inc., Framingham, MA, USA) into the systemic ventricle as bridge to transplantation, with the sub-pulmonary ventricle left unsupported.Discussion We present our institutional strategy for VAD selection in these patients and highlight intra-corporeal VAD implantation technique.

The continual shortage of hearts for transplantation (HTx) led to the expansion of the donor pool by accepting older donors. We compared the medium-term follow-up of patients after HTx with older hearts (over the age of 63 years) with those of patients after HTx with younger hearts.

Evolution of ventricular assist devices (VADs) leading to miniaturization has made intracorporeal implantation in children feasible. Ventricular assist device therapy for anthracycline-induced cardiomyopathy (CMP) in adults has been reported. We report the case of an 8-year-old child (body surface area 0.97 m2) presenting with anthracycline-induced CMP being successfully treated with an intracorporeal left ventricular assist device (LVAD) as a bridge to candidacyrecovery. We present our institutional algorithm, which advises intracorporeal LVAD implantation for long-term ventricular assist, in children with a body surface area >0.6 m2. Advantages are better mobilization and the possibility to discharge home, leading to enhanced quality of life.