Impact of delayed sternal closure on wound infections following neonatal and infant cardiac surgery.

OBJECTIVES: Delayed sternal closure is a routine procedure to reduce hemodynamic and respiratory instability in pediatric patients following cardiac surgery, particularly in neonates and infants. In this setting, the possible links between sternal wound infection and delayed sternal closure are still a matter of debate. As a part of our routine, there was a low threshold for delayed sternal closure, so we reviewed our experience with sternal wound infections with a focus on potentially related perioperative risk factors, particularly delayed sternal closure. METHODS: We retrospectively identified 358 operated neonates (37%) and infants (mean age 3.6 months) in our local congenital heart disease database between January 2013 and June 2017. Potential risk factors for sternal wound infections, such as age, gender, complexity (based on Aristotle- and STS-EACTS mortality category), reoperation, use of cardiopulmonary bypass, extracorporeal membrane oxygenation, mortality and delayed sternal closure (163/358, 46%), were subjected to uni- and multivariate analysis. RESULTS: A total of 26/358 patients (7.3%) developed a superficial sternal wound infection. There were no deep sternal wound infections, no mediastinitis or sepsis. Applying univariate analysis, the prevalence of sternal wound infections was related to younger age, more complex surgery and delayed sternal closure. However, in multivariate analysis, sternal wound infection was only associated with delayed sternal closure (p = 0.013, odds ratio 8.6). Logistic regression revealed the prevalence of delayed sternal closure to be related to younger age, complexity, and the use of extracorporeal membrane oxygenation. CONCLUSION: In patients younger than one year, sternal wound infections are clearly related to delayed sternal closure. However, in our cohort, all sternal wound infections were superficial and acceptable, considering the improved postoperative hemodynamic stability.

Long-Term Outcome Up To 40 Years after Single Patch Repair of Complete Atrioventricular Septal Defect in Infancy or Childhood.

OBJECTIVES: Patients with repaired complete atrioventricular septal defect (CAVSD) represent an increasing portion of grown-ups with congenital heart disease. For repair of CAVSD, the single-patch technique has been employed first. This technique requires division of the bridging leaflets, thus, among other issues, long-term function of the atrioventricular valves is of particular concern. METHODS: Between 1978 and 2001, 100 consecutive patients with isolated CAVSD underwent single-patch repair in our institution. Hospital mortality was 11%. Primary endpoints were clinical status, atrioventricular valve function, and freedom from reoperation in long term. Follow-up was obtained contacting the patient and/or caregiver, and the referring cardiologist. RESULTS: Eighty-three patients were eligible for long-term follow-up (21.0 ± 8.7, mean ± standard deviation [21.5; 2.1-40.0, median; min-max] years after surgical repair). Actual long-term mortality was 3.4%. Quality of life (QoL; self- or caregiver-reported in patients with Down syndrome) was excellent or good in 81%, mild congestive heart failure was present in 16%, moderate in 3.6% as estimated by New York Heart Association classification. Echocardiography revealed normal systolic left ventricular function in all cases. Regurgitation of the right atrioventricular valve was mild in 48%, mild-moderate in 3.6%, and moderate in 1.2%. The left atrioventricular valve was mildly stenotic in 15% and mild to moderately stenotic in 2%; regurgitation was mild in 54%, mild to moderate in 13%, and moderate in 15% of patients. Freedom from left atrioventricular-valve-related reoperation was 95.3, 92.7, and 89.3% after 5, 10, and 30 years, respectively. Permanent pacemaker therapy, as an immediate result of CAVSD repair (n = 7) or as a result of late-onset sick sinus syndrome (n = 5), required up to six reoperations in single patients. Freedom from pacemaker-related reoperation was 91.4, 84.4, and 51.5% after 5, 10, and 30 years, respectively. CONCLUSION: Up to 40 years after single-patch repair of CAVSD, clinical status and functional results are promising, particularly, in terms of atrioventricular valve function. Permanent pacemaker therapy results in a life-long need for surgical reinterventions.

Impact of hepatopathy in pediatric patients after surgery for complex congenital heart disease.

Patients undergoing complex pediatric cardiac surgery in early infancy are at risk of postoperative secondary end-organ dysfunction. The aim of this study was to determine specific risk factors promoting the development of peri- and postoperative hepatopathy after surgery for congenital heart disease. In this retrospective study, we identified 20 consecutive patients operated between 2011 and 2019 from our institutional cohort who developed significant postsurgical hepatic dysfunction. These patients were compared to a control group of 30 patients with comparable initial cardiac conditions and STS-EACTS risk score. Patients who developed hepatopathy in the intensive care unit have chronic cholestasis and decreased liver synthesis. The impact of postoperative hepatopathy on morbidity was marked. In six patients (30%), liver transplantation was executed as ultima ratio, and two (10%) were listed for liver transplantation. The overall mortality related to postoperative hepatopathy is high: We found nine patients (45%) having severe hepatopathy and mostly multiple organ dysfunction who died in the postoperative course. According to risk analysis, postoperative right and left heart dysfunction in combination with a postoperative anatomical residuum needing a re-operation or re-intervention in the postoperative period is associated with a high risk for the development of cardiac hepatopathy. Furthermore, postoperative complications (pleural effusion, heart rhythm disorders, etc.), postoperative infections, and the need for parenteral nutrition also raise the risk for cardiac hepatopathy. Further investigations are needed to reduce hepatic complications and improve the general prognosis of such complex patients.

Impact of delayed systemic heparinization on postoperative bleeding and thromboembolism during post-cardiotomy extracorporeal membrane oxygenation in neonates.

INTRODUCTION: Veno-arterial extracorporeal membrane oxygenation is well-established for pediatric patients with post-cardiotomy heart failure. However, extracorporeal membrane oxygenation support is associated with major complications, that is, hemorrhage and thromboembolism. We seek to report our experience with delayed systemic heparinization during neonatal cardiac extracorporeal membrane oxygenation and its impact on bleeding and thromboembolism. METHODS: We retrospectively identified 15 consecutive neonates who were placed on extracorporeal membrane oxygenation after congenital heart surgery during a period of 3 years (2015-2017). Our anticoagulation protocol consisted of full heparin reversal by protamine after switching from cardiopulmonary bypass to extracorporeal membrane oxygenation (target activated clotting time: 120 ± 20 seconds). Administration of systemic heparinization was delayed until postoperative drainage volume declined to <1 mL/kg/h. Primary study endpoints were thromboembolism, bleeding, and requirement of blood products on extracorporeal membrane oxygenation. RESULTS: Our cohort (mean age: 13 ± 2.6 days; mean weight: 3.1 ± 0.3 kg; 66.7% male) required post-cardiotomy extracorporeal membrane oxygenation with a mean support time of 4.5 ± 2.2 days. Systemic heparinization was delayed averagely for 18.1 ± 9.3 hours. No thromboembolic events were observed on extracorporeal membrane oxygenation or after weaning. Relevant surgical site bleeding occurred in two patients (13.3%) requiring re-thoracotomy on the first postoperative day. Analysis of transfusion volumes revealed 24.5 ± 21.9 mL/kg/d mean packed red blood cells, 9.6 ± 7.1 mL/kg/d mean fresh frozen plasma, and 7.5 ± 5.7 mL/kg/d mean platelets. In-hospital survival was 86.6% (n = 13). CONCLUSION: In this retrospective analysis, the results of delayed systemic heparinization in neonatal post-cardiotomy extracorporeal membrane oxygenation could lead one to conclude that this routine is safe and favorable with low risk for thromboembolic events, reduced postoperative hemorrhage, and reduced blood product utilization.

Aortopexy offers surgical options for a variety of pathological tracheal conditions in paediatric patients.

OBJECTIVES: Aortopexy is widely used; however, many surgeons still regard it with suspicion. To date, there are only a few large series and minimal long-term data. Against this background, our goal was to report our experience, particularly with regard to the recent expansion of indications and modification of diagnostic routine and surgical strategy. METHODS: Between 1994 and 2012, 53 patients (mean age: 1.1 years; 5 weeks-10.2 years) were operated on. Tracheomalacia after the operation for oesophageal atresia was the main indication for aortopexy (74%), followed by tracheal compression by the innominate artery (17%) and other selected indications (9%). Computed tomography angiography has emerged in recent years as the method of choice for preoperative diagnosis. Median sternotomy has replaced lateral thoracotomy, and intraoperative bronchoscopy has become the standard. RESULTS: In contrast to magnetic resonance imaging, computed tomography angiography resulted in perfect visualization of the condition. Median sternotomy and simultaneous bronchoscopy led to immediate readjustment of the aortopexy sutures in 6 patients. There were no surgical deaths or serious morbidities. The mean follow-up was 4.9 (0.3-14.9) years. Two patients with additional complex diseases died during the follow-up period. In all survivors, symptoms improved markedly or disappeared. However, we observed an increased susceptibility to lower respiratory tract infections over the long-term (32%). CONCLUSIONS: Aortopexy is effective for treating tracheomalacia of different origins and other pathological conditions as well. Preoperative computed tomography angiography offers excellent visualization of the condition. Median sternotomy and intraoperative bronchoscopy provide a combination for reliable operative and long-term results. However, many patients still have an increased susceptibility to lower respiratory tract infections.

Ross Procedure in Neonates and Infants: A European Multicenter Experience.

BACKGROUND: Infants and neonates with severe left ventricular outflow tract obstruction may require pulmonary autograft replacement of the aortic root. In this retrospective multicenter cohort study, we present our experience with the Ross procedure in neonates and infants with a focus on midterm survival and pulmonary autograft durability. METHODS: A retrospective observational study was performed in 76 infants (aged less than 1 year) operated on in six congenital cardiac centers in The Netherlands and Germany between 1990 and 2013. RESULTS: Patients had a pulmonary autograft replacement of the aortic valve with (68%) or without (32%) septal myectomy. Median patient age was 85 days (range, 6 to 347). Early mortality (n = 13, 17%) was associated with neonatal age, preoperative use of intravenous inotropic drugs, and congenital aortic arch defects. Five patients (9%) died during follow-up. Freedom from autograft reintervention was 98% at 10 years. Echocardiography demonstrated good valve function, with no or trace regurgitation in 73% of patients. Freedom from right ventricular outflow tract reintervention was 51% at 10 years. Univariable analysis demonstrated superior freedom from reintervention of pulmonary homografts compared with aortic homografts or xenografts. CONCLUSIONS: Pulmonary autograft replacement of the aortic valve in neonates and infants is a high-risk operation but offers a durable neoaortic valve. Midterm durability reflects successful adaptation of the autograft to the systemic circulation. Late mortality associated with heart failure was an unexpected finding.

Expression of inflammation in myocardial tissue of rabbits: comparison of two miniaturized heart-lung machines.

The majority of cases involving the surgical treatment of congenital heart disease require implementation of cardiopulmonary bypass (CPB). However, neonates and infants are particularly prone to serious complications associated with CPB as a result of capillary leak due to cardiovascular failure. These complications are related to the transfusion of foreign blood, the disproportionately large area of contact between the patient's blood and foreign material, as well as the systemic inflammatory response induced by hemolysis. To attenuate these risks, we developed a novel, highly integrative, miniaturized heart-lung machine (MiniHLM) with a static priming volume of only 102 mL. This prototype was tested in comparison with a conventional heart-lung machine (static priming volume 213 mL) using a rabbit animal model. The animals were anesthetized, sternotomized, and connected to CBP via the aorta and right atrium. The aorta was cross-clamped for 1 h. Blood samples for examination were taken at regular intervals. Biopsies of the right atrial appendage (RAA) were removed directly after initiation and after cessation of CPB. After gradual reduction of perfusion with the HLM, all rabbits were successfully weaned from CPB, and the sternum was closed. Foreign blood was not administered in all cases. After cryopreservation of the RAA tissue, de novo transcription of inflammatory cytokines was measured by means of real-time polymerase chain reaction using the comparative CT method. No significant differences in the expression of the inflammatory parameters of the myocardial tissue samples were found between the study groups.

Prevention of postoperative pericardial adhesions with TachoSil.

BACKGROUND: The prevention of the pericardial adhesions largely accountable for the technical difficulty and risk of injury inherent to resternotomy continues to gain in importance with the increasing frequency of reoperations. The hemostatic sponge TachoSil (Nycomed Austria GmbH, Linz, Austria), has shown promising results in adhesion prevention in several regions of the body. This study was designed to evaluate its effectiveness in the prevention of pericardial adhesions in comparison with the Gore-Tex (W. L. Gore and Assoc, Flagstaff, AZ) surgical membrane and a control. METHODS: Twenty-four rabbits were distributed into 3 groups: TachoSil, Gore-Tex, or no barrier agent (control). After median sternotomy and pericardiotomy, the cardial surface was exposed to the aggravating effects of room air, irrigation, and gauze abrasion for one hour. A pericardial defect was created and repaired with one of the barrier agents, or left uncovered (control). Resternotomy was performed after 6 months for the evaluation of adhesion formation. RESULTS: Significantly fewer macroscopic adhesions were observed with TachoSil than Gore-Tex in all regions (p < 0.05) excluding the coronary arteries, where the difference in favor of TachoSil did not achieve significance (0.05< p-value <0.10). TachoSil also demonstrated significantly fewer retrosternal adhesions than the control, as well as a universal non-significant trend of fewer adhesions in all regions. The limited lesions present in the TachoSil group were filmy in nature and removed with blunt dissection relatively easily. No significant differences were found between Gore-Tex and the control. Microscopically, the least pronounced fibrosis formation and inflammatory reaction was detected with TachoSil. CONCLUSIONS: TachoSil is effective in the prevention of pericardial adhesions.

A newly developed miniaturized heart-lung machine--expression of inflammation in a small animal model.

Cardiopulmonary bypass may cause severe inflammatory reactions and multiorgan failure, especially in premature and low-weight infants. This is due in part to the large area of contact with extrinsic surfaces and the essential addition of foreign blood. Thus, we developed a new miniaturized heart-lung machine (MiniHLM) with a total static priming volume of 102mL (including arterial and venous lines) and tested it in a small animal model. Seven Chinchilla Bastard rabbits were perfused with the MiniHLM (dynamic priming volume 127mL). Seven animals serving as a control were perfused using Dideco Kids and a Stöckert roller pump (modified dynamic priming volume 149mL). The rabbits were anesthetized and sternotomized, followed by cannulation of the aorta and the right atrium. The aorta was clamped for 1h. Blood for examination of inflammation (TNF-α, IL-1ß, IL-6, IL-8, and IL-10) and blood gas analysis were taken before skin incision, 5min before opening of the aorta, 15min after opening of the aorta, and 4 h after the initiation of cardiopulmonary bypass. The parameters of inflammation were expressed by means of the comparative C(T) method (ΔΔC(T) method). After gradual reduction of perfusion with the HLM, the heart was decannulated, and the sternum was closed. All rabbits were successfully weaned from cardiopulmonary bypass. Blood gas analysis was unremarkable in all cases. Foreign blood was not administered. Although statistical significance was not achieved, there was a reduced expression of inflammatory markers in the MiniHLM group. The newly developed MiniHLM prototype was tested successfully in a small animal model in terms of technical function and expression of inflammation. Upcoming tests with the industrially manufactured MiniHLM may reveal the advantages of the MiniHLM in comparison with the conventional HLM.

Fibrin-polylactide-based tissue-engineered vascular graft in the arterial circulation.

There is a clear clinical requirement for the design and development of living, functional, small-calibre arterial grafts. Here, we investigate the potential use of a small diameter, tissue-engineered artery in a pre-clinical study in the carotid artery position of sheep. Small-calibre ( approximately 5 mm) vascular composite grafts were molded using a fibrin scaffold supported by a poly(L/D)lactide 96/4 (P(L/D)LA 96/4) mesh, and seeded with autologous arterial-derived cells prior to 28 days of dynamic conditioning. Conditioned grafts were subsequently implanted for up to 6 months as interposed carotid artery grafts in the same animals from which the cells were harvested. Explanted grafts (n = 6) were patent in each of the study groups (1 month, 3 months, 6 months), with a significant stenosis in one explant (3 months). There was a complete absence of thrombus formation on the luminal surface of grafts, with no evidence for aneurysm formation or calcification after 6 months in vivo. Histological analyses revealed remodeling of the fibrin scaffold with mature autologous proteins, and excellent cell distribution within the graft wall. Positive vWf and eNOS staining, in addition to scanning electron microscopy, revealed a confluent monolayer of endothelial cells lining the luminal surface of the grafts. The present study demonstrates the successful production and mid-term application of an autologous, fibrin-based small-calibre vascular graft in the arterial circulation, and highlights the potential for the creation of autologous implantable arterial grafts in a number of settings.

The Aachen miniaturized heart-lung machine--first results in a small animal model.

Congenital heart surgery most often incorporates extracorporeal circulation. Due to foreign surface contact and the administration of foreign blood in many children, inflammatory response and hemolysis are important matters of debate. This is particularly an issue in premature and low birth-weight newborns. Taking these considerations into account, the Aachen miniaturized heart-lung machine (MiniHLM) with a total static priming volume of 102 mL (including tubing) was developed and tested in a small animal model. Fourteen female Chinchilla Bastard rabbits were operated on using two different kinds of circuits. In eight animals, a conventional HLM with Dideco Kids oxygenator and Stöckert roller pump (Sorin group, Milan, Italy) was used, and the Aachen MiniHLM was employed in six animals. Outcome parameters were hemolysis and blood gas analysis including lactate. The rabbits were anesthetized, and a standard median sternotomy was performed. The ascending aorta and the right atrium were cannulated. After initiating cardiopulmonary bypass, the aorta was cross-clamped, and cardiac arrest was induced by blood cardioplegia. Blood samples for hemolysis and blood gas analysis were drawn before, during, and after cardiopulmonary bypass. After 1 h aortic clamp time, all animals were weaned from cardiopulmonary bypass. Blood gas analysis revealed adequate oxygenation and perfusion during cardiopulmonary bypass, irrespective of the employed perfusion system. The use of the Aachen MiniHLM resulted in a statistically significant reduced decrease in fibrinogen during cardiopulmonary bypass. A trend revealing a reduced increase in free hemoglobin during bypass in the MiniHLM group could also be observed. This newly developed Aachen MiniHLM with low priming volume, reduced hemolysis, and excellent gas transfer (O(2) and CO(2)) may reduce circuit-induced complications during heart surgery in neonates.

Pancarditis in a five-year-old boy affecting tricuspid valve and ventricular septum.

A five-year-old boy with a structurally normal heart and recent history of adenotomy and gastroenteritis presented with Staphylococcus aureus pancarditis including endocarditis of the tricuspid valve and abscess of the ventricular septum. Surgical treatment consisted of debridement of the valvar vegetations and of the septal abscess. A seven-day continuous mediastinal irrigation with iodine solution was conducted to eliminate local infection sites as well as to prevent from constrictive pericarditis. The patient recovered uneventfully and is in excellent clinical condition with no residues one year after surgery.

The in vitro development of autologous fibrin-based tissue-engineered heart valves through optimised dynamic conditioning.

Our group has previously demonstrated the synthesis of a completely autologous fibrin-based heart valve structure using the principles of tissue engineering. The present approach aims to guide more mature tissue development in fibrin-based valves based on in vitro conditioning in a custom-designed bioreactor system. Moulded fibrin-based tissue-engineered heart valves seeded with ovine carotid artery-derived cells were subjected to 12 days of mechanical conditioning in a bioreactor system. The bioreactor pulse rate was increased from 5 to 10 b.p.m. after 6 days, while a pressure difference of 20 mmH(2)O was maintained over the valve leaflets. Control valves were cultured under stirred conditions in a beaker. Cell phenotype and extracellular matrix (ECM) composition were analysed in all samples and compared to native ovine aortic valve tissue using routine histological and immunohistochemical techniques. Conditioned valve leaflets showed reduced tissue shrinkage compared to stirred controls. Limited ECM synthesis was evident in stirred controls, while the majority of cells were detached from the fibrin scaffold. Dynamic conditioning increased cell attachment/alignment and expression of alpha-smooth muscle actin, while enhancing the deposition of ECM proteins, including types I and III collagen, fibronectin, laminin and chondroitin sulphate. There was no evidence for elastin synthesis in either stirred controls or conditioned samples. The present study demonstrates that the application of low-pressure conditions and increasing pulsatile flow not only enhances seeded cell attachment and alignment within fibrin-based heart valves, but dramatically changes the manner in which these cells generate ECM proteins and remodel the valve matrix. Optimised dynamic conditioning, therefore, might accelerate the maturation of surgically feasible and implantable autologous fibrin-based tissue-engineered heart valves.

Novel "biomechanical" polymeric valve prostheses with special design for aortic and mitral position: a future option for pediatric patients?

In children, systemic heart valve replacement with bioprostheses is associated with accelerated valve degeneration, and mechanical prostheses require permanent anticoagulation. Novel "biomechanical" polymeric valve prostheses ("bio" = flexible, "mechanical" = synthetic), solely made of polycarbonate urethane (PCU), were tested in vitro and in a growing animal (calf) model with the aim of improved durability without permanent anticoagulation. The trileaflet aortic prosthesis has diminished pressure loss and reduced stress and strain peaks. The asymmetric bileaflet mitral valve mimics natural nonaxial inflow. The valves underwent long-term in vitro testing and in vivo testing in growing calves for 20 weeks [mitral (7), aortic (7)] with comparison to different commercial bioprostheses [mitral (7), aortic (2)]. In vitro durability of PCU valves was proved up to 20 years. Survival of PCU valves versus bioprostheses was 7 versus 2 mitral and 5 versus 0 aortic valves, respectively. Two animals with PCU aortic valves died of pannus overgrowth causing left ventricular outflow tract obstruction. Degeneration and calcification were mild (mitral) and moderate (aortic) in PCU valves but were severe in biological valves. There was no increased thrombogenicity of the PCU valves compared to bioprostheses. The novel polymeric valve prostheses revealed superior durability compared to current bioprostheses in growing animal model without permanent anticoagulation and thus, may be a future option for pediatric patients.

Hypertensive pulmonary vascular disease in adults with secundum or sinus venosus atrial septal defect.

BACKGROUND: The development of hypertensive pulmonary vascular disease (HPVD) is considered a risk factor in the long-term course of patients with secundum atrial septal defects (ASD). The aim of this study was to assess the prevalence and histologic degree of HPVD and pulmonary hypertension in relation to preoperative clinical and hemodynamic data, intraoperative findings, and operative outcome in adults. METHODS: Lung biopsies of 75 patients, mean age 44 +/- 14 years (18-71 years), with secundum ASD or sinus venosus defect including ten patients with partial anomalous pulmonary venous return were analyzed in accordance with preoperative and intraoperative findings as well as operative outcome. Lung biopsy was performed at the time of defect closure and was classified according to Heath and Edwards. RESULTS: Structural changes of the pulmonary vasculature were found in 59% of patients; grade 3 and higher changes were present in 19%. There were no statistically significant relations between histologic findings and preoperative clinical and hemodynamic data, intraoperative findings, and operative outcome. The prevalence of moderate (32-50 mm Hg) and severe (> 50 mm Hg) systolic pulmonary hypertension was 27% and 17%, respectively. Increased systolic pulmonary arterial pressure was associated with increased pulmonary vascular resistance (p < 0.000) and patients' age (p = 0.001). Patients with a lower functional capacity had a higher prevalence of pulmonary hypertension (p = 0.011). CONCLUSIONS: The prevalence of HPVD and pulmonary hypertension in adult patients with secundum ASD or sinus venosus defect is considerable. Preoperative hemodynamic data do not predict the degree of HPVD in lung biopsy. Closure is generally advised to prevent increasing pulmonary arterial pressure and decreasing functional capacity over time.