Three-Dimensional Printing of Congenital Heart Disease Models for Cardiac Surgery Simulation: Evaluation of Surgical Skill Improvement among Inexperienced Cardiothoracic Surgeons

Objective@#To evaluate the impact of surgical simulation training using a three-dimensional (3D)-printed model of tetralogy of Fallot (TOF) on surgical skill development. @*Materials and Methods@#A life-size congenital heart disease model was printed using a Stratasys Object500 Connex2 printer from preoperative electrocardiography-gated CT scans of a 6-month-old patient with TOF with complex pulmonary stenosis.Eleven cardiothoracic surgeons independently evaluated the suitability of four 3D-printed models using composite Tango 27, 40, 50, and 60 in terms of palpation, resistance, extensibility, gap, cut-through ability, and reusability of. Among these, Tango 27 was selected as the final model. Six attendees (two junior cardiothoracic surgery residents, two senior residents, and two clinical fellows) independently performed simulation surgeries three times each. Surgical proficiency was evaluated by an experienced cardiothoracic surgeon on a 1–10 scale for each of the 10 surgical procedures. The times required for each surgical procedure were also measured. @*Results@#In the simulation surgeries, six surgeons required a median of 34.4 (range 32.5–43.5) and 21.4 (17.9–192.7) minutes to apply the ventricular septal defect (VSD) and right ventricular outflow tract (RVOT) patches, respectively, on their first simulation surgery. These times had significantly reduced to 17.3 (16.2–29.5) and 13.6 (10.3–30.0) minutes, respectively, in the third simulation surgery (p = 0.03 and p = 0.01, respectively). The decreases in the median patch appliance time among the six surgeons were 16.2 (range 13.6–17.7) and 8.0 (1.8–170.3) minutes for the VSD and RVOT patches, respectively. Summing the scores for the 10 procedures showed that the attendees scored an average of 28.58 ± 7.89 points on the first simulation surgery and improved their average score to 67.33 ± 15.10 on the third simulation surgery (p = 0.008). @*Conclusion@#Inexperienced cardiothoracic surgeons improved their performance in terms of surgical proficiency and operation time during the experience of three simulation surgeries using a 3D-printed TOF model using Tango 27 composite.

Three-Dimensional Printing of Congenital Heart Disease Models for Cardiac Surgery Simulation: Evaluation of Surgical Skill Improvement among Inexperienced Cardiothoracic Surgeons

Objective@#To evaluate the impact of surgical simulation training using a three-dimensional (3D)-printed model of tetralogy of Fallot (TOF) on surgical skill development. @*Materials and Methods@#A life-size congenital heart disease model was printed using a Stratasys Object500 Connex2 printer from preoperative electrocardiography-gated CT scans of a 6-month-old patient with TOF with complex pulmonary stenosis.Eleven cardiothoracic surgeons independently evaluated the suitability of four 3D-printed models using composite Tango 27, 40, 50, and 60 in terms of palpation, resistance, extensibility, gap, cut-through ability, and reusability of. Among these, Tango 27 was selected as the final model. Six attendees (two junior cardiothoracic surgery residents, two senior residents, and two clinical fellows) independently performed simulation surgeries three times each. Surgical proficiency was evaluated by an experienced cardiothoracic surgeon on a 1–10 scale for each of the 10 surgical procedures. The times required for each surgical procedure were also measured. @*Results@#In the simulation surgeries, six surgeons required a median of 34.4 (range 32.5–43.5) and 21.4 (17.9–192.7) minutes to apply the ventricular septal defect (VSD) and right ventricular outflow tract (RVOT) patches, respectively, on their first simulation surgery. These times had significantly reduced to 17.3 (16.2–29.5) and 13.6 (10.3–30.0) minutes, respectively, in the third simulation surgery (p = 0.03 and p = 0.01, respectively). The decreases in the median patch appliance time among the six surgeons were 16.2 (range 13.6–17.7) and 8.0 (1.8–170.3) minutes for the VSD and RVOT patches, respectively. Summing the scores for the 10 procedures showed that the attendees scored an average of 28.58 ± 7.89 points on the first simulation surgery and improved their average score to 67.33 ± 15.10 on the third simulation surgery (p = 0.008). @*Conclusion@#Inexperienced cardiothoracic surgeons improved their performance in terms of surgical proficiency and operation time during the experience of three simulation surgeries using a 3D-printed TOF model using Tango 27 composite.

Experience with Mechanical Circulatory Support for Medically Intractable Low Cardiac Output in a Pediatric Intensive Care Unit

BACKGROUND AND OBJECTIVES: Mechanical circulatory support with extracorporeal membrane oxygenation (ECMO) and ventricular assist device has always been the optimal choice for treating the majority of medically intractable low cardiac output case. We retrospectively investigated our institution's outcomes and variables associated with a high risk of mortality. SUBJECTS AND METHODS: From 1999 to 2014, 86 patients who were of pediatric age or had grown-up congenital heart disease underwent mechanical circulatory support for medically intractable low cardiac output in our pediatric intensive care unit. Of these, 9 grown-up congenital heart disease patients were over 18 years of age, and the median age of the subject group was 5.82 years (range: 1 day to 41.6 years). A review of all demographic, clinical, and surgical data and survival analysis were performed. RESULTS: A total of 45 (52.3%) patients were successfully weaned from the mechanical assist device, and 25 (29.1%) survivors were able to be discharged. There was no significant difference in results between patients over 18 years and under 18 years of age. Risk factors for mortality were younger age (<30 days), functional single ventricle anatomy, support after cardiac operations, longer support duration, and deteriorated pre-ECMO status (severe metabolic acidosis and increased levels of lactate, creatinine, bilirubin, or liver enzyme). The survival rate has improved since 2010 (from 25% before 2010 to 35% after 2010), when we introduced an upgraded oxygenator, activated heart transplantation, and also began to apply ECMO before the end-stage of cardiac dysfunction, even though we could not reveal significant correlations between survival rate and changed strategies associated with ECMO. CONCLUSION: Mechanical circulatory support has played a critical role and has had a dramatic effect on survival in patients with medically intractable heart failure, particularly in recent years. Meticulous monitoring of acid-base status, laboratory findings, and early and liberal applications are recommended to improve outcomes without critical complication rates, particularly in neonates with single ventricle physiology.

Clinical Characteristics and Independent Factors Related to Long-Term Outcomes in Patients with Left Isomerism

BACKGROUND AND OBJECTIVES: We studied the results of patient management for left isomerism (LI) and sought to determine factors that may influence survival and prognosis. SUBJECTS AND METHODS: We reviewed the medical records of 76 patients who were compatible with LI criteria between 1982 and 2014. RESULTS: Of the total study population, 29 patients (38.1%) had functional univentricular heart disease, 43 patients (56.5%) had cardiac anomalies suitable for biventricular hearts, and four patients (5.2%) had normal heart structure. Extracardiac anomalies were noted in 38.1% of the study population, including biliary atresia in 7.8% of all patients. Of the 25 patients who underwent Kawashima procedures, 24.0% developed pulmonary arteriovenous fistulas (PAVFs). During the median follow-up period of 11.4 years (range: 1 day to 32 years), 14 patients died. The 10-year, 20-year, and 30-year survival rates were 87%, 84%, and 76%, respectively. Preoperative dysrhythmia and uncorrected atrioventricular valve regurgitation were significantly associated with late death. There was no significant difference in the number of surgical procedures and in survival expectancy between patients in the functional single-ventricle group and in the biventricular group. However, late mortality was higher in functional single-ventricle patients after 18 years of age. CONCLUSION: Patients with LI need to be carefully followed, not only for late cardiovascular problems such as dysrhythmia, valve regurgitation, and the development of PAVFs, but also for noncardiac systemic manifestations.

Long-Term Results after Surgical Treatment of Ebstein's Anomaly: a 30-year Experience

BACKGROUND AND OBJECTIVES: The aim of the study is to evaluate the long-term results after a surgical repair of Ebstein's anomaly. SUBJECTS AND METHODS: Forty-eight patients with Ebstein's anomaly who underwent open heart surgery between 1982 and 2013 were included. Median age at operation was 5.6 years (1 day-42.1 years). Forty-five patients (93.7%) demonstrated tricuspid valve (TV) regurgitation of less than moderate degree. When the patients were divided according to Carpentier's classification, types A, B, C, and D were 11, 21, 12, and 4 patients, respectively. Regarding the type of surgical treatment, bi-ventricular repair (n=38), one-and-a half ventricular repair (n=5), and single ventricle palliation (n=5) were performed. Of 38 patients who underwent a bi-ventricular repair, TV repairs were performed by Danielson's technique (n=20), Carpentier's technique (n=11), Cone repair (n=4), and TV annuloplasty (n=1). Two patients underwent TV replacement. Surgical treatment strategies were different according to Carpentier's types (p<0.001) and patient's age (p=0.022). RESULTS: There were 2 in-hospital mortalities (4.2%; 1 neonate and 1 infant) and 2 late mortalities during follow-up. Freedom from recurrent TV regurgitation rates at 5, 10, and 15 years were 88.6%, 66.3%, 52.7%, respectively. TV regurgitation recurrence did not differ according to surgical method (p=0.800). Survival rates at 5, 10, and 20 years were 95.8%, 95.8%, and 85.6%, respectively, and freedom from reoperation rates at 5, 10, and 15 years were 85.9%, 68.0%, and 55.8%, respectively. CONCLUSION: Surgical treatment strategies were decided according to Carpentier's type and patient's age. Overall survival and freedom from reoperation rates at 10 years were 95.8% and 68.0%, respectively. Approximately 25% of patients required a second operation for TV during the follow-up.

Potts Shunt in Patients with Primary Pulmonary Hypertension

Idiopathic pulmonary arterial hypertension eventually leads to right-sided heart failure and sudden death. Its mortality rate in children is still high, despite improvements in pharmacological therapy, and therefore novel treatments are necessary. The Potts shunt, which creates an anastomosis between the left pulmonary artery and the descending aorta, has been proposed as a theoretically promising palliative surgical technique to decompress the right ventricle. We report the case of a 12-year-old girl with suprasystemic idiopathic pulmonary hypertension and right ventricular failure who underwent a Potts shunt for palliation with good short-term results.

Safety and Efficacy of the Off-Label Use of Milrinone in Pediatric Patients with Heart Diseases

BACKGROUND AND OBJECTIVES: Milrinone is often used in children to treat acute heart failure and prevent low cardiac output syndrome after cardiac surgery. Due to the lack of studies on the long-term milrinone use in children, the objective of this study was to assess the safety and efficacy of the current patterns of milrinone use for > or =3 days in infants and children with heart diseases. SUBJECTS AND METHODS: We retrospectively reviewed the medical records of patients aged or =3 days from January 2005 to December 2012. Patients' characteristics including age, sex, height, weight, and body surface area were recorded. The following parameters were analyzed to identify the clinical application of milrinone: initial infusion rate, maintenance continuous infusion rate, total duration of milrinone therapy, and concomitantly infused inotropes. The safety of milrinone was determined based on the occurrence of adverse events such as hypotension, arrhythmia, chest pain, headache, hypokalemia, and thrombocytopenia. RESULTS: We assessed 730 admissions (684 patients) during this period. Ventricular septal defects were the most common diagnosis (42.4%) in these patients. Milrinone was primarily used after cardiac surgery in 715 admissions (97.9%). The duration of milrinone treatment varied from 3 to 64.4 days (> or =7 days in 149 admissions). Ejection fraction and fractional shortening of the left ventricle improved in patients receiving milrinone after cardiac surgery. Dose reduction of milrinone due to hypotension occurred in only 4 admissions (0.5%). Although diverse arrhythmias occurred in 75 admissions (10.3%), modification of milrinone infusion to manage arrhythmia occurred in only 3 admissions (0.4%). Multivariate analysis indicated that the development of arrhythmia was not influenced by the pattern of milrinone use. CONCLUSION: Milrinone was generally administered for > or =3 days in children with heart diseases. The use of milrinone for > or =3 days was effective in preventing low cardiac output after cardiac surgery when combined with other inotropes, suggesting that milrinone could be safely employed in pediatric patients with heart diseases.

Valved Conduit with Glutaraldehyde-Fixed Bovine Pericardium Treated by Anticalcification Protocol

BACKGROUND: A preclinical study was conducted for evaluating a valved conduit manufactured with a glutaraldehyde (GA)-fixed bovine pericardium treated using an anticalcification protocol. METHODS: Bovine pericardia were decellularized, fixed with GA in an organic solvent, and detoxified. We prepared a valved conduit using these bovine pericardia and a specially designed mold. The valved conduit was placed under in vitro circulation by using a mock circulation model, and the durability under mechanical stress was evaluated for 2 months. The valved conduit was implanted into the right ventricular outflow tract of a goat, and the hemodynamic, radiologic, histopathologic, and biochemical results were obtained for 6 months after the implantation. RESULTS: The in vitro mock circulation demonstrated that valve motion was good and that the valved conduit had good gross and microscopic findings. The evaluation of echocardiography and cardiac catheterization demonstrated the good hemodynamic status and function of the pulmonary xenograft valve 6 months after the implantation. According to specimen radiography and a histopathologic examination, the durability of the xenografts was well preserved without calcification at 6 months after the implantation. The calcium and inorganic phosphorus concentrations of the explanted xenografts were low at 6 months after the implantation. CONCLUSION: This study demonstrated that our synergistic employment of multiple anticalcification therapies has promising safety and efficacy in the future clinical study.

The Anti-calcification Effect of Dithiobispropionimidate, Carbodiimide and Ultraviolet Irradiation Cross-linking Compared to Glutaraldehyde in Rabbit Implantation Models

BACKGROUND: Glutaraldehyde (GA) is a widely used cross-linking agent for improving mechanical properties and resistance to enzymatic degradation of collagenous tissue, but it has several drawbacks such as calcification and cytotoxicity. The aim of this study was to find the alternative effective cross-linking methods to GA. MATERIALS AND METHODS: Bovine pericardium was processed with GA with ethanol+octanol and glycine detoxification, and polyethylene glycol (PG) space filler, dimethyl 3,3'-dithiobispropionimidate (DTBP), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) treatment, and the physical fixation of ultraviolet irradiation were done. The biologic material properties of variously treated pericardial tissues were assessed by biochemical, mechanical and histological tests. Treated pericardial tissues were also implanted subcutaneously or intramuscularly into the rabbit for 10 weeks to assess the xenoreactive antibody response of immunoglobulin G and M, their anti-calcification effect. RESULTS: The biochemical and mechanical properties of EDC fixed pericardial tissues were comparable to the GA fixed tissue. The cytotoxicity was lowest in space filler treated GA fixed group. In rabbit subcutaneous or intramuscular implantation models, decellularization, space filler, EDC treatment group showed significantly lower calcium content than GA only and DTBP treatment group (p<0.05, analysis of variance). The titer of anti Galalpha1-3Galbeta1-4GlcNAc-R antibodies did not change in the postimplantation serial enzyme-linked immunosorbent assay. Hematoxylin and eosin and von Kossa staining showed that decellularization, space filler, EDC, and ultraviolet treatment had less inflammatory cell infiltration and calcium deposits. CONCLUSION: The decellularization process, PG filler, and EDC treatments are good alternative cross-linking methods compared to GA only fixation and primary amine of DTBP treatment for cardiovascular xenograft preservation in terms of the collagen cross-linking stability and in vivo anti-calcification effects.

Clinical Course of Vascular Rings and Risk Factors Associated With Mortality

BACKGROUND AND OBJECTIVES: Vascular rings refer to anomalies of the great arteries that cause respiratory or feeding problems. The purpose of this study was to analyze a series of patients with vascular rings and evaluate associated risk factors for mortality. SUBJECTS AND METHODS: A retrospective review of all patients identified with vascular rings between 1997 and 2010 in the Seoul National University Children's Hospital. RESULTS: Thirty-five patients were diagnosed with vascular rings (median age at diagnosis, 7 months). The vascular rings of 32 patients were confirmed by cardiac computed tomography or magnetic resonance imaging. The types of vascular rings were: a double aortic arch in ten patients, a right aortic arch with persistent left ligamentum arteriosum in seven, an aberrant subclavian artery in seven, a pulmonary sling in eight, and others types in three patients. Eleven patients were asymptomatic. Gastrointestinal and respiratory symptoms were seen in ten and sixteen patients, respectively. Associated cardiovascular anomalies were present in fifteen patients. Twenty patients with definite symptoms underwent surgical treatment. The median interval between diagnosis and operation was 6 days. Four patients eventually died; three deaths were associated with complex heart diseases, and one had pulmonary artery sling with severe tracheal stenosis. Only the presence of a complex heart disease significantly influenced mortality (p=0.002). CONCLUSION: Vascular rings include several types of anomalies, each with a different prognosis and symptoms. The presence of a complex heart disease was significantly associated with mortality. Early diagnosis and timely surgery in symptomatic patients are essential.

Recent Trends in Indications of Fetal Echocardiography and Postnatal Outcomes in Fetuses Diagnosed as Congenital Heart Disease

BACKGROUND AND OBJECTIVES: We hypothesized that fetal echocardiography (echoCG) is an accurate diagnostic tool reflecting well postnatal echoCG findings and outcomes. SUBJECTS AND METHODS: We reviewed the medical records of 290 pregnant women, including 313 fetuses, who were examined by fetal echoCG at the Seoul National University Children's Hospital from January 2008 through April 2011. RESULTS: The mean gestational age at diagnosis was 26.2+/-5.2 weeks. The mean age of mothers at diagnosis was 31.7+/-3.8 years. We identified indications for fetal echoCG in 279 cases. The most common indication was abnormal cardiac findings in obstetrical screening sonography (52.0%). Among the 313 echoCG results, 127 (40.6%) were normal, 13 (4.2%) were minor abnormalities, 35 (11.2%) were simple cardiac anomalies, 50 (16.0%) were moderate cardiac anomalies, 60 (19.2%) were complex cardiac anomalies, 16 (5.1%) were arrhythmias, and 12 (3.8%) were twin-to-twin transfusion syndrome. The most common congenital heart disease was tetralogy of Fallot (23 fetuses, 15.9%). One hundred forty-eight neonates were examined by echoCG. We analyzed differences between fetal echoCG and postnatal echoCG. In 131 (88.5%) cases, there was no difference; in 15 (10.1%), there were minor differences; and in only 2 (1.4%) cases, there were major differences. CONCLUSION: There is a recent increase in abnormal cardiac findings of obstetric ultrasonography screenings that indicate fetal echoCG. Fetal echoCG is still a good, accurate diagnostic method for congenital heart disease.

A Comparative Study on Mechanical and Biochemical Properties of Bovine Pericardium After Single or Double Crosslinking Treatment

BACKGROUND AND OBJECTIVES: Glutaraldehyde (GA) has been used as a representative method of tissue preservation in cardiovascular surgery. However, GA has showed limited durability including calcification, mechanical failure and toxicity. To overcome those unsolved problems, we analyzed the crosslinking differences of primary amines, GA and genipin in their mechanical and biochemical properties with a single or double crosslinking agent for clinical application. MATERIALS AND METHODS: Samples were divided into 3 groups; control, single crosslinking fixation and double crosslinking fixation after decellurarization using bovine pericardium. For analysis of the biochemical and mechanical properties of each crosslinking method, tensile strength, percentage strain, thermal stability, resistance to pronase, nynhydrin and cytotoxicity test were studied. RESULTS: Combined hexamethylene diamine and suberic acid in the carbodiimide hydrochloride/N-hydroxysucinimide solution (EDC/NHS) after decellurarization, tensile strength and strain percentage were not statistically significant compared to the single crosslinking treated groups (p>0.05). Tissue crosslinking stability was weak in single treatment of diphenylphosphoryl azide, suberic acid, low concentration of EDC, hexamethylene diamine and procyanidin groups, but thermal stability and resistance to the pronase and ninhydrin were markedly increased in concentrated EDC/NHS or after combined double treatment with low concentration of GA or genipin (p<0.001). CONCLUSION: Single or double crosslinking with low concentration of carbodiimide, diphenylphosphonyl azide, procyanidin, suberic acid and hexane diamine were not as effective in mechanical, biochemical, cytotoxic and crosslinking properties compared to GA or genipin fixation, but their mechanical and chemical properties were much improved when combined with low concentrations of GA or genipin in the double crosslinking process.

Histologic Characteristics and Mechanical Properties of Bovine Pericardium Treated with Decellularization and alpha-Galactosidase: A Comparative Study

BACKGROUND: Bioprostheses for cardiovascular surgery have limitations in their use following as calicification. alpha-galactosidase epitope is known as a stimulant of immune response and then shows a progressing calcification. The objective of this study was to evaluate histologic characteristics and mechanical properties of decellularization and treated with alpha-galactosidase. MATERIALS AND METHODS: Bovine pericardial tissues were allocated into three groups: fixation only with glutaraldehyde, decellularization with sodium dodesyl sulfate and decellularization plus treatment with alpha-galactosidase. We confirmed immunohistological characteristics and mechanical properties as fatigue test, permeability test, compliance test, tensile strength (strain) test and thermal stability test. RESULTS: Decellularization and elimination of alpha-gal were confirmed through immunohistologic findings. Decellularization had decreased mechanical properties compared to fixation only group in permeability (before fatigue test p=0.02, after fatigue test p=0.034), compliance (after fatigue test p=0.041), and tensile strength test (p=0.00). The group of decellularization plus treatment with alpha-galactosidase had less desirable mechanical properties than the group of decellularization in concerns of permeability (before fatigue test p=0.043) and strain test (p=0.001). CONCLUSION: Favorable decellularization and elimination of alpha-gal were obtained in this study through immunohistologic findings. However, those treatment including decellularization and elimination of alpha-gal implied the decreased mechanical properties in specific ways. We need more study to complete appropriate ioprosthesis with decellularization and elimination of alpha-gal including favorable mechanical properties too.

Changes of the Structural and Biomechanical Properties of the Bovine Pericardium after the Removal of alpha-Gal Epitopes by Decellularization and alpha-Galactosidase Treatment

BACKGROUND: Bovine pericardium is one of the most widely used materials in bioprosthetic heart valves. Immunologic responses have been implicated as potential causes of limited durability of xenogenic valves. This study aimed to determine the effectiveness of decellularization and alpha-galactosidase (alpha-gal) to remove major xenoreactive antigens from xenogenic tissues. MATERIALS AND METHODS: Recombinant Bacteroides thetaiotaomicron (B. thetaiotaomicron) alpha-gal or decellularization, or both were used to remove alpha-gal from bovine pericardium. It was confirmed by alpha-gal-bovine serum albumin-based enzyme-linked immunosorbent assay (ELISA), high-performance anion exchange chromatography, flow cytometry, 3,3'-diaminobenzidine-staining, and lectin-based ELISA. The mechanical properties of bovine pericardium after decellularization or alpha-gal treatment were investigated by tests of tensile-strength, permeability, and compliance. Collagen fiber rearrangement was also evaluated by a 20,000x transmission electron microscope (TEM). RESULTS: Recombinant B. thetaiotaomicron alpha-gal could effectively remove alpha-gal from bovine pericardium B. thetaiotaomicron (0.1 U/mL, pH 7.2) while recombinant human alpha-gal removed it recombinant human alpha-gal (10 U/mL, pH 5.0). There was no difference in the mechanical properties of fresh and recombinant alpha-gal-treated bovine pericardium. Furthermore, the TEM findings demonstrated that recombinant alpha-gal made no difference in the arrangement of collagen fiber bundles with decellularization. CONCLUSION: Recombinant B. thetaiotaomicron alpha-gal effectively removed alpha-gal from bovine pericardium with a small amount under physiological conditions compared to human recombinant alpha-gal, which may alleviate the harmful xenoreactive immunologic responses of alpha-gal. Recombinant alpha-gal treatment had no adverse effects on the mechanical properties of bovine pericardium.

Effect of Hyperkalemia and Hemolysis Caused by Hyperacute Rejection on Cardiac Function in Pig to Human Ex Vivo Xenogeneic Cardiac Perfusion Model

BACKGROUND AND OBJECTIVES: Hyperacute rejection (HAR) is a major obstacle to successful xenotransplantation of vascularized organs. This study was conducted to observe the effect of hemolysis of perfused human whole blood on pig heart function, and determine the major risk factors for preservation of xenoperfused cardiac function using ex-vivo pig to human xenogeneic cardiac perfusion model. MATERIALS AND METHODS: Harvested pig hearts were perfused with normal human whole blood (group 1), two different types of pre-treated human whole blood (group 2: immunoglobulins were depleted by plasmapheresis, group 3: pre-treated with plasmapheresis, GAS914, cobra venom factor (CVF) and steroid), and normal porcine whole blood as control (group 4) for 3 hours. RESULTS: Duration of heart beat was significantly prolonged in group 2 and group 3. Histological examination showed widespread HAR features but was gradually delayed in groups 2 and 3 compared to group 1. The absolute levels of serum creatine kinase-MB and Troponin I increased gradually, and was lower in group 3. Serum hemoglobin levels were rapidly increased in groups 3 and 4, compared to group 1. Extracellular potassium level increased sharply from the beginning of blood perfusion in groups 1, 2 and 3, compared to group 4. CONCLUSION: Pretreatment of human whole blood, including immunoglobulin depletion, CVF and steroid reduced and delayed the destruction of pig myocardium by HAR. However, the increased extracellular potassium levels in groups 1, 2 and 3 reflected that these treatments could not prohibit myocardial injury by HAR.

Effect of Trypsin on Physico-dynamic and Histological Changes after Decellularization of Bovine Pericardium / 대한흉부외과학회지

BACKGROUND: Various decellularization methods have been studied in order to develop tissue graft which is less immunogenic and more durable. This study was performed to investigate the physico-dynamic and histological effect of trypsin pretreatment on decellularization protocols. MATERIAL AND METHOD: Two groups of bovine pericardium specimen each underwent decellularization process based on SDS and Triton X-100 or N-lauroylsarcosinate and Triton X-100. Two more groups additionally underwent pretreatment with 0.1% Trypsin/0.1% EDTA. After decellularization process, mechanical tensile strength was tested, then iomechanical test of permeability and compliance was tested before and after fatigue test. Light microscopy and electron microscopy was performed to observe histological findings. RESULT: There was no difference in mechanical tensile strength between groups, but permeability and compliance was decreased in trypsin pretreated groups. Light microscopic and electron microscopic findings revealed damage of the extracellular matrix in trypsin pretreated groups and in groups which underwent the fatigue test also. CONCLUSION: Trypsin pretreatment in decellularizing process of bovine pericardium damages extracellular matrix and increases permeability and compliance of the bovine pericardium, but did not decrease tensile strength. Further studies are needed to use enzymatic treatments in decellularization protocols.

Study on Effective Preservation of Bovine Pericardium Using Decellularization and alpha-galactosidase for Eliminating Xenoreactive Antigen / 대한흉부외과학회지

BACKGROUND: Effective decellularization and fixation process is critical, in order to use xenogenic valves clinically. In the present study, we decellularized bovine pericardium using sodium dodecyl sulfate (SDS) and N-lauroyl sarcosinate, treated with alpha-galactosidase, and then fixed in various manners, to find out the most effective tissue preservation & fixation procedure. MATERIAL AND METHOD: Bovine pericardium was decellularized with SDS and N-lauroyl sarcosinate, and treated with alpha-galactosidase. Both groups were fixed differently, by varying glutaraldehyde (GA) or EDC (1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide)/N-hydroxysuccinamide (NHS) treatment conditions. Thereafter, physical examination, tensile strength test, thermal stability test, cytotoxicity test, pronase test, pronase-ninhydrin test, purpald test, permeability test, compliance test, H&E staining, DNA quantification, and alpha-galactose staining were carried out to each groups. RESULT: GA fixed groups showed better physical properties and thermal stability than EDC/NHS fixed groups. EDC/NHS-GA dual fixed groups showed better physical properties and thermal stability than EDC/NHS fixed groups, and showed better thermal stability than GA fixed groups. In pronase test and pronase-ninhydrin test, GA fixed groups and EDC/NHS-GA dual fixed groups showed stronger crosslinks than EDC/NHS groups. Permeability and compliance tended to increase in EDC/NHS-GA dual fixed groups, compared to GA fixed groups. But, EDC/NHS-GA dual fixed groups had stronger tensile strength and lower cytotoxicity than GA fixed groups. CONCLUSION: We have verified that EDC/NHS-GA dual fixation can make effective crosslinks and lower the toxicity of GA fixation. Henceforth, we will verify if EDC/NHS-GA dual fixation can lower calcifications & tissue failure in vivo experiment.

Measurement of Porcine Aortic and Pulmonary Valve Geometry and Design for Implantable Tissue Valve / 대한흉부외과학회지

BACKGROUND: As life expectancy has been increased, the cardiac valve disease has been increased. In past, mechanical valve for valve replacement surgery was used widely, but it has many weaknesses, such as hemorrhage, teratogenic effect caused by warfarin, acute mechanical failure, taking warfarin during life, etc. So, the tissue valve is used widely and researches for durability of tissue valve are in progress. Tissue valves being used are all imported in Korea, and there is a lack of information on its geometry and design. So, we studied the geometry of porcine aortic and pulmonary valve, and tried to suggest theoretical basis for making the aortic and pulmonary valve. MATERIAL AND METHOD: We harvested aortic and pulmonary valves of 25 pigs and measured the geometry of valve at fresh and glutaraldehyde (GA) fixed state. In each group, we measured the diameter of the base, diameter of commissure, valve height, commissural height, etc. Also, for making implantable porcine and bovine pericardial valve, we designed the valve stent form, thickness, height, and leaflet size, form, thickness by different size of valve. RESULT: The aortic and pulmonary valve geometry and ratio were measured in each group. The right coronary cusp of aortic valve and right facing cusp of pulmonary valve was bigger than other cusps and non coronary cusp was smaller than others (RCC:NCC:LCC=1:0.88:1). Valve height was correlated to the leaflet size. We designed the outer diameter of stented porcine aortic valve from 19 mm to 33 mm and designed stent height and width, using previous measured ratio of each structure, stent thickness, working thickness (for making valve). Also, we designed the size of stent and form for stented bovine pericardial valve, considering diameter of valve, leaflet length, height and leaflet minimum coaptation area. CONCLUSION: By measuring of 25 pig's aortic and pulmonary valve geometry and ratio, we can make theoretical basis for making implantable stented porcine valve and bovine pericardial valve in various size. After making implantable valve using these data, it is necessary to do in vivo and in vitro researches, furthermore.

The Recent Surgical Result of Total Anomalous Pulmonary Venous Return

BACKGROUND AND OBJECTIVES: Recent surgical results from total anomalous pulmonary venous return (TAPVR) are reported to have improved; however, mortality and morbidity are still high in the univentricles. This review was performed in order to demonstrate surgical results from TAPVR for recent years in a single institute. SUBJECTS AND METHODS: A total of 53 patients with TAPVR underwent surgery between January 2000 and December 2008. Preoperative anatomy and hemodynamics were evaluated by 2-dimensional echocardiogram. We reviewed medical records on preoperative management, age, and body weight at time of surgery, postoperative mortality, and pulmonary venous obstruction. RESULTS: The study included 36 biventricle patients and 17 univentricle patients. Median age and weight at time of surgery were 26 days and 3.5 kg, respectively. During the mean follow up period of 48.2 months, a total of 11 deaths and 8 early deaths occurred. Postoperative pulmonary venous stenosis occurred in 8 patients. Among 36 biventricle patients, mortality occurred in 1 patient and postoperative pulmonary venous stenosis occurred in 6 patients. No statistical significances were observed between postoperative pulmonary venous stenosis and other factors. Among 17 univentricule patients, mortality was 10, including 7 early deaths, and postoperative pulmonary venous stenosis occurred in 2 patients. Combined palliations were modified Blalock-Taussig (BT) shunts in 7, pulmonary artery banding (PAB) in 3, bidirectional cavopulmonary shunt in 5, and the Fontan procedure in 1. The highest mortality was recorded in patients with a modified BT shunt (85.7%) and next in patients with PAB (66.6%). Mortality was not related to anatomy of TAPVR, nor preoperative obstruction, but with significant age and weight at time of surgery. CONCLUSION: Despite improvement in operative results from TAPVR, surgery in univentricles is highly risky, especially with low weight and early age, with concomitant palliation.

Bloodless Cardiac Surgery in a Neonate Weighing 2.8 kg / 대한흉부외과학회지

Despite increased interest in bloodless cardiac surgery, its use has been mostly confined to adult patients. Especially, bloodless pediatric cardiovascular surgery using cardiopulmonary bypass has been avoided mainly due to hemodilution. Authors recently experienced a case of bloodless cardiac surgery in a 2.8 kg-weighing neonate whose parents were Jehovah's Witness.