A Record Book of Open Heart Surgical Cases between 1959 and 1982, Hand-Written by a Cardiac Surgeon

A book of brief records of open heart surgery underwent between 1959 and 1982 at Seoul National University Hospital was recently found. The book was hand-written by the late professor and cardiac surgeon Yung Kyoon Lee (1921–1994). This book contains valuable information about cardiac patients and surgery at the early stages of the establishment of open heart surgery in Korea, and at Seoul National University Hospital. This report is intended to analyze the content of the book.

Medical Student Examination Questions for Thoracic and Cardiovascular Surgery of Almost 60 Years Ago

Medical student examination questions of 60 years ago are very rare to find irrespective of medical specialty. Recently, medical student examination questions for thoracic and cardiovascular surgery were found, which were presented between 1957 and 1959 at Seoul National University Medical College. All examination questions were hand-written in six pages by a professor as examiner. Among the six pages, four examination papers were dated and/or the target grade was identified, while the remaining two did not offer any information. These materials are thought to have a valuable historical meaning for the Korean medical community as well as the Department of Thoracic and Cardiovascular Surgery at Seoul National University Hospital.

A Thoracic Surgical Case Presented at the First Academic Meeting of the Chosun (Korean) Medical Association Held in 1947

The late Prof. Kyeok Boo Han (1913–2005) was one of the pioneers in the early stages of the establishment of thoracic surgery in Korea. He was in charge of thoracic surgery at Seoul National University Hospital from 1948 to the outbreak of the Korean War in 1950. He presented a thoracic surgical case entitled “Adhesive (constrictive) pericarditis: one surgical case” at the first academic meeting of the Chosun (an old name for Korea) Medical Association, held in 1947. This presentation is considered to be the first thoracic surgical case presented by a Korean surgeon at a domestic medical meeting after the National Liberation from Japanese colonial rule in 1945. In this regard, this study was intended to analyze the content and the meaning of the case, published in a journal in 1948.

Analysis of 39 Letters Concerned with the Late Professor Lee YK and Dr Lillehei and the Letters Were Written between Apr. 1958 and Dec. 1981 / 대한흉부외과학회지

Dr Lillehei (1918~1999) pioneered cardiac surgery with his landmark operations using cross-circulation in 1954 and 1955. With his dedications to open heart surgery, he is generally considered to be the father of open heart surgery by many medical historians. Dr Lillehei expanded his contributions to cardiac surgery with training 134 cardiothoracic surgeons at the University of Minnesota Hospital and he trained an additional 20 surgeons at the Cornell Medical Center. Dr Lillehei's trainees came from all over the world and Dr YK Lee (1921~1994) of Seoul National University was among them. He joined the University of Minnesota Hospital in 1957 as a part of the Minnesota project. During his stay for two years, in addition to experimental research, he learned clinical cardiac surgery as part of Dr Lillehei's team. In 1959, after returning to Korea, Dr Lee began his career as a full-time cardiac surgeon with establishing the Division of Cardiac Surgery at Seoul National University Hospital. Yet he encountered many difficult barriers in the process. During that time, Dr Lillehei was willing to share his experience and he provided many valuable resources for cardiac operations. With Dr Lillehei's kind help, the open heart surgery program was gradually and successfully established at Seoul National University Hospital. These two surgical titans from across the Pacific Ocean died in 1994 (Dr Lee) and 1999 (Dr Lillehei). They are gone, yet the proud Korean people have not forgotten them.

Lecture Note of a Thoracic Surgeon, Fifty More Years Ago / 대한흉부외과학회지

The late Professor Lee CB (1915~1967) was one of the pioneers in the early stages of thoracic surgery in Korea while he was in charge of the Department of Thoracic and Cardiovascular Surgery at Seoul National University Hospital as the first director from 1957 until he died of liver cancer in 1967. He was a graduate from the old Seoul National University, and he dedicated himself to the field of lung surgery after he joined the army during the Korean War, which broke out in 1950. Among his many contributions to pulmonary surgery, he performed the first partial lung resection in Korea in 1953. His lecture notes were recently found. These lecture notes for medical students were written by hand in late 1950s. Considering the content and form of the lecture notes, they are thought to have very significant historical value. The lecture notes were a total of 277 pages on general thoracic surgery and cardiovascular surgery with 75 self-drawn figures. This study was intended to facilitate a better understanding of the history of thoracic surgery in Korea, and especially for young thoracic surgeons. These notes may well contribute to the field of Thoracic and Cardiovascular Surgery in Korea.

The First Written Medical Record on Thoracic Surgery in Korean History / 대한흉부외과학회지

On Dec 22, 1909, a young patriot called Lee Jae-Myung (1986~1910) attempted to assassinate Lee Wan-Yong, the prime minister of the last Yi Choseon cabinet and he later signed the annexation treaty with imperial Japan. Despite that Lee Jae-Myung failed in this assassination attempt, his heroic deed motivated national pride thereafter. After this attempted assassination, a medical record was prepared about stab wound that was inflicted upon Lee Wan-Yong during the trial of Lee Jae-Myung, and this record included many significant specific descriptions that were concerned with thoracic surgery. They included an intercostal stab wound and intercostal arterial hemorrhage, lung injury, chest contusion, traumatic pleuritis and supposedly pneumo-and hemothorax. Thoracentesis for drainage of the serosanguinous pleural effusion was also mentioned. This medical record is judged to be the first written medical record on thoracic surgery in Korean history. The aim of this study is to analyze the content of the record as it is related with a well known episode in modern Korean history.

Neuroprotective Effect of Phenytoin and Hypothermia on a Spinal Cord Ischemic Injury Model in Rabbits / 대한흉부외과학회지

BACKGROUND: Spinal cord ischemic injury during thoracic and thoracoabdominal aortic surgeries remains a potentially devastating outcome despite using various methods of protection. Neuronal voltage-dependent sodium channel antagonists are known to provide neuroprotection in cerebral ischemic models. This study was designed to compare the neuroprotective effects of phenytoin with those of hypothermia in a rabbit model of spinal cord ischemia. MATERIAL AND METHOD: Spinal cord ischemia was induced in New Zealand white rabbits by means of infrarenal aortic cross clamping for 25 minutes. Four groups of 8 animals each were studied. The control group and the hypothermia group received retrograde infusion of saline only (22degrees C, 2 mL/min); the normothermic phenytoin group and the hypothermicphenytoin group received retrograde infusion of 100 mg of phenytoin at different rectal temperatures (39degrees C and 37degrees C, respectively) during the ischemic period. The neurologic function was assessed at 24 and 72 hours after the operation with using the modified Tarlov criteria. The spinal cords were harvested after the final neurologic examination for histopathological examination to objectively quantify the amount of neuronal damage. RESULT: No major adverse effects were observed with the retrograde phenytoin infusion during the aortic ischemic period. All the control rabbits became severely paraplegic. Both the phenytoin group and the hypothermia group had a better neurological status than did the control group (p<0.05). The typical morphological changes that are characteristic of neuronal necrosis in the gray matter of the control animals were demonstrated by means of the histopathological examination, whereas phenytoin or hypothermia prevented or attenuated these necrotic phenomena (p<0.05). The number of motor neuron cells positive for TUNEL staining was significantly reduced, to a similar extent, in the rabbits treated with phenytoin or hypothermia. Phenytoin and hypothermia had some additive neuroprotective effect, but there was no statistical significance between the two on the neurological and histopathological analysis. CONCLUSION: The neurological and histopathological analysis consistently demonstrated that both phenytoin and hypothermia may afford significant spinal cord protection to a similar extent during spinal cord ischemia in rabbits, although no significant additive effects were noticed.

A Cardiac Surgeon from the USA who had Worked in Korea a Half Century Ago: Dr. George Schimert / 대한흉부외과학회지

Dr. George Schimert, born in 1918 in Switzerland, received his medical degrees from universities in Hungary and in Germany. After immigration to the United States, he continued medical training at several hospitals. In 1956, for pursuit of cardiac surgery, he had joined the group headed by Dr. Walt Lillehei at the University of Minnesota. During this period, in 1958, he joined Seoul National University Hospital as a overall medical adviser and adviser in surgery for 15 months in partnership with the University of Minnesota Medical School. During his stay in Korea, in addition to the works in the medical administration and education, he contributed to the early establishment of thoracic surgery program. In August 6, 1959, he performed open heart surgery using cardiopulmonary bypass for an ASD patient at Seoul National University Hospital. However, the patient died 6 hours after the operation. In 1960, after returning to the United States, he began his career at Buffalo General Hospital as the first director of its cardiac surgery program. In 1985, the Dr. George Schimert Lectureship and Medical Conference was established to honor his contributions and achievements. He died December 7, 2002.

Histologic Changes of the Immunologically Untreated Xenogenic Valved Conduit / 대한흉부외과학회지

BACKGROUND: It has been shown that the endothelium of cardiac valves and adjacent great vessels have a reduced immune reaction compared to other vessels. We investigated the clinical feasibility of using immunologically untreated xenogenic valves, in a pig-to-goat pulmonary valve conduit implantation model. MATERIAL AND METHOD: Porcine pulmonary valve conduits were prepared without specific immunologic treatment and implanted into the right ventricular outflow tract of goats while undergoing cardiopulmonary bypass. Two goats each were assigned to the following observation time intervals: one day, one week, three months, six months and twelve months. Echocardiographic examinations were performed prior to sacrifice of the goat to evaluate pulmonary valve function. After the xenograft specimens were retrieved, histological changes were evaluated microscopically. RESULT: Ten of the twelve animals survived the predetermined observation time intervals. Aneurysmal dilatations, of the anterior wall of the implanted pulmonary artery, were observed at each of three and twelve month-survival animals. A variable degree of pulmonary valve regurgitation was observed on echocardiography. However, valve stenosis, thrombotic occlusion and vegetation were not seen. Microscopically, the nuclei of the donor tissue disappeared as a result of pyknosis and karyolysis; however the three components of the implanted xenografts (the pulmonary artery, the valve and the infundibulum) were gradually replaced by host cells over time, while maintaining their structural integrity. CONCLUSION: Immunologically untreated xenogenic pulmonary valve conduits were replaced by host cells with few observed clinical problems in a pig to goat pulmonary valve implantation model. Therefore, they might be an alternative bioprosthesis option.

Comparative Analysis of Medical Terminology Among Korea, China, and Japan in the Field of Cardiopulmonary Bypass / 대한흉부외과학회지

BACKGROUND: Vocabularies originating from Chinese characters constitute an important common factor in the medical terminologies used in 3 eastern Asian countries; Korea, China and Japan. This study was performed to comparatively analyze the medical terminologies of these 3 countries in the field of cardiopulmonary bypass (CPB) and; thereby, facilitate further understanding among the 3 medical societies. MATERIAL AND METHOD: A total of 129 English terms (core 85 and related 44) in the field of CPB were selected and translated into each country's official terminology, with help from Seoul National University Hospital (Korea), Tokyo Mitsui Memorial Hospital (Japan), and Yanbian University Fuzhi Hospital and Harbin Children Hospital (China). Dictionaries and CPB textbooks were also cited. In addition to the official terminology used in each country, the frequency of use of English terms in clinical settings was also analyzed. RESULT: Among the 129 terms, 28 (21.7%) were identical between the 3 countries, as based on the Chinese characters. 86 terms were identical between only two countries, mostly between Korea and Japan. As a result, the identity rate in CPB terminology between Korea and Japan was 86.8%; whereas, between Korea and China and between Japan and China the rates were both 24.8%. The frequency of use of English terms in clinical practices was much higher in Korea and Japan than in China. CONCLUSION: Despite some inherent limitations involved in the analysis, this study can be a meaningful foundation in facilitating mutual understanding between the medical societies of these 3 eastern Asian countries.

Time-related Histopathologic Changes of Fresh Frozen Vascular Xenograft in Pig-to-goat Model / 대한흉부외과학회지

BACKGROUND: As determined from the recent investigations of discordant cardiac xenotransplantation, hyperacute rejection occurs mainly at the endothelial cells in donor microvascular systems, but this does not occur at cardiac valve leaflets or at medium-to-large caliber vessels. On the basis of this background, this study was performed to look into the biocompatibility for transplantation of a middle or large diameter xenogenic blood vessel by conducting xenogenic arterial transplantation with the carotid artery in a pig-to-goat model. MATERIAL AND METHOD: The experimental group was composed of 10 pairs of pig-to-goat combinations. They were divided into each period of 1 week, and 1, 3, 6 and 12 months. Four carotid artery grafts obtained through collection of the bilateral carotid arteries from two pigs were preserved at -70degrees C without other treatment, and then they were transplanted into the bilateral carotid arteries of two goats. Doppler ultrasonography was done on a periodic basis after transplantation to evaluate the patency of the grafted blood vessel. At the ends of a predetermined period, the grafts were explanted from the goats and they underwent gross examination. Hematoxylin-eosin and Masson's trichrome staining were conducted. In addition, in order to examine the immunological rejection of the grafted xenogenic blood vessel, immunohistochemical staining was conducted with T-lymphocyte indicator and von Willebrand factor. RESULT: Two goats at the each one-week period and the one-year period died during the experimental period because of a reason unrelated to the experimental procedure, and the remaining 8 goats survived until the end of each experiment period. On Doppler ultrasonography, unilateral carotid artery occlusion was found in a goat, whose period was specified as 3 months, among the 8 survived goats. However, the vascular patency was maintained well and there was no graft that formed aneurysms in the other goats. On gross examination, the region of vascular anastomosis was preserved well, and calcification of the grafted blood vessel was not shown. Histologically, the endothelial cells of the graft disappeared one week after transplantation, and then there was progressive spread of the recipients' endothelial cells from the anastomotic site. The reendothelialization occurred over the whole graft at one month after transplantation. The neointimal thickening and adventitial inflammation became severe by 3 months after transplantation, but this lessened at 6 months and 12 months, respectively. The rate of CD3 positive cells was very low among the infiltrated inflammatory cells. CONCLUSION: The fresh-frozen xenogenic artery kept its patency without being greatly influenced by xenogenic immune reaction.

Rectal Temperature Maintenance Using a Heat Exchanger of Cardioplegic System in Cardiopulmonary Bypass Model for Rats / 대한흉부외과학회지

BACKGROUND: Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. The main advantages of a small animal model include the reduced cost and time, and the fact that it does not require a full scale operating environment. However the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by a heat exchanger is among them. The purpose of this study is to comfirm the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. MATERIAL AND METHOD: The miniature circuit consisted of a reservoir, heat exchanger, membrane oxygenator, roller pump, and static priming volume was 40 cc. Ten male Sprague-Dawley rats (mean weight 530 gram) were divided into two groups, and heat exchanger (HE) group was subjected to CPB with HE from a cardioplegia system, and control group was subjected to CPB with warm water circulating around the reservoir. Partial CPB was conducted at a flow rate of 40 mg/kg/min for 20 min after venous cannulation (via the internal juglar vein) and arterial cannulation (via the femoral artery). Rectal temperature were measured after anesthetic induction, after cannulation, 5, 10, 15, 20 min after CPB. Arterial blood gas with hematocrit was also analysed, 5 and 15 min after CPB. RESULT: Rectal temperature change differed between the two groups (p<0.01). The temperatures of HE group were well maintained during CPB, whereas control group was under progressive hypothermia. Rectal temperature 20 min after CPB was 36.16+/-0.32 degrees C in the HE group and 34.22+/-0.36 degrees C in the control group. CONCLUSION: We comfirmed the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. This model would be a valuable tool for further use in hypothermic CPB experiment in rats.

Histological Comparison of Vascular Grafts in a Pig to Goat Xenotransplantation Model / 대한흉부외과학회지

BACKGROUND: Current vascular prostheses are considered still inadequate for reconstruction of small-diameter vessels. To evaluate the potential use of xenograft vessels as small diameter arterial grafts, we implanted porcine vessels in goats. The grafts were treated with two different processes, freezing and acellularization, before implantation, and gross inspection as well as microscopic examination followed after a predetermined period. MATERIAL AND METHOD: Bilateral porcine carotid arteries were harvested and immediately stored at -70 degrees C within tissue preservation solution. One of them was designated as frozen xenograft vessel. The other one was put on acellularization process using NaCl-SDS solution and stored frozen until further use. Grafts were implanted in the place of carotid arteries of the same goat. The grafts have remained implanted for 1, 3, and 6 months in three animals, respectively. Periodic ultrasonographic examinations were performed during the observation period. After explantation, the grafts were analyzed grossly and histologically under light microscope. RESULT: All animals survived the experimental procedure without problems. Ultrasonographic examinations showed excellent patency of all the grafts during the observation period. Gross examination revealed nonthrombotic, patent lumens with smooth surfaces. Microscopic examinations of the explanted grafts showed cellular reconstruction at the 6-month stage in both grafts. Although more inflammatory responses were observed in the early phase of frozen xenografts, there was no evidence of significant rejection. CONCLUSION: These findings suggest that porcine xenograft vessels, regardless of pre-implantation processes of acelluarization or freezing, can be acceptably implanted in goats, although short duration of observation in a small number of animals may limit this study.

Histological Analysis of Autologous Pericardial Tissue Used as a Small-Diameter Arterial Graft / 대한흉부외과학회지

BACKGROUND: Current vascular prostheses are still inadequate for reconstruction of small-diameter vessels. Autologous pericardium can be a good alternative for this purpose as it already possesses good blood compatibility and shows a mechanical behavior similar to that of natural arteries. However, the clinical use of autologous pericardial tissue as a small-diameter vascular graft has limitations due to mixed outcomes from uncertain biological behavior and difficulty to gain reliable patency results in animal experiments. To study this issue, we implanted fresh and glutaraldehyde-treated autologous pericardium as small-diameter arterial grafts in dogs, and compared their time-related changes histologically. MATERIAL AND METHOD: As a form of 5mm-diameter arterial graft, one pair of autologous pericardial tissue was used for comparison between the glutaraldehyde-treated and the glutaraldehyde-untreated grafts in the bilateral carotid arteries in the same dog. The patency of the grafts were evaluated at regular intervals with Doppler ultrasonography. After the predetermined periods of 3 days, 2 weeks, 1 month, 3 months and 6 months, the grafts in each animal were explanted. The retrieved grafts were processed for light and electron microscopic analyses following gross observation. RESULT: Of 7 animals, 2 were excluded from the study because one died postoperatively due to bleeding and the other was documented as one side of the grafts being obstructed. All 10 grafts in the remaining 5 dogs were patent. Grossly, a variable degree of thromboses were observed in the luminal surfaces of the grafts at 3 days and 2 weeks, despite good patency. Pseudointimal smooth blood-contacting surfaces were developed in the grafts at 1 month and later. By light microscopy, mesothelial cell layers of the pericardial tissue were absent in all explanted grafts. Newly formed endothelial cell layers on the blood-contacting surface were observed in both the glutaraldehyde-treated and fresh grafts at 3 months and later. The collagen fibers became degraded by fragmentation in the fresh graft at 1 month and in the glutaraldehyde-treated graft at 3 months. At 6 months, the collagen layers were no longer visible in either the glutaraldehyde-treated or fresh grafts. By electron microscopy, a greater amount of coarse fibrin fibers were observed in the fresh grafts than in the glutaraldehyde-treated grafts and, more compact and well-arrayed layers were observed in the glutaraldehyde-treated grafts than in the fresh grafts. CONCLUSION: The glutaraldehyde-treated small-diameter pericardial arterial grafts showed a better endothelialization of the blood-contacting surface and a slower fragmentation of the collagen layers than the fresh grafts, although it has yet to be proven whether these differences are so significant as to affect the patency results between the groups.

Neuroprotective Effect of Cyclosporin A on Spinal Cord Ischemic Injury in Rabbits / 대한흉부외과학회지

BACKGROUND: The purpose of this study is to ascertain the neuroprotective effect of cyclosporin A on the 25-min surgical ischemia model in the spinal cords of rabbits with neuropathological correlation and histoimmunochemical analyses. MATERIAL AND METHOD: Thirty-two New Zealand white rabbits were randomly divided into four groups: Rabbits were randomly divided into four groups: the control I2 group (n=8), the control I7 group (n=8), the cyclosporin Cs2 group (n=8), and the cyclosporin Cs7 group (n=8). The I2 group underwent a 25-min aortic cross- clamp without intervention and were sacrificed on the 2nd day postoperatively, while the I7 group underwent a 25- min of aortic cross-clamp without intervention and were sacrificed on the 7th day postoperatively. The Cs2 group received cyclosporin A (25 mg/kg) intravenously 15 min after the 25-min cross-clamp and were sacrificed on the 2nd day postoperatively, while the Cs7 group received cyclosporin A (25 mg/kg) intravenously 15 min after the 25- min cross-clamp and were sacrificed on the 7th day postoperatively. The rabbits underwent 25-min surgical aortic cross-clamp. Neurologic functions were evaluated on the 2nd day and 7th postoperative day using Tarlov scoring system. After scoring neurologic function, all rabbits were sacrificed for histopathologic observation. RESULT: All rabbits survived the experimental procedure. The values of Tarlov score did not show any differences between the control and cyclosporin groups on the 2nd day. The scores of group Cs7 (2.75+/-0.89) were significantly higher than those of group I7 (1.25+/-1.39) on the 7th day (p<0.05). On the histologic exanminations, specimens of the spinal cord showed necrosis and apoptosis. The pathologic scores of group Cs7 (1.0+/-0.53) was less than those of group I7 (2.13+/-1.36, p<0.05). TUNEL staing showed apoptosis of the specimen in group I2 and Cs2 but there was no stastically significant difference between groups on the score. There were more overexpression of HSP70 and nNOS in cyclosporine group than in control group. CONCLUSION: We think that cyclosporin A may decrease neuronal cell death with induced upregulation of HSP70 against 25-min ischemia of the spinal cord in the rabbit.

Current Status of Cardiopulmonary Perfusionists in the Republic of Korea / 대한흉부외과학회지

BACKGROUND: The primary responsibility of a perfusionist is to operate the heart-lung bypass machine during open heart surgery, which is vital for the successful operative outcome. However, despite the perfusionist's crucial role on the cardiac surgical team, no relevant studies have not yet been conducted in our country. In this regard, this study was performed about the current status of perfusionists in Korea with comparative analysis on the certification and education system of perfusionists in foreign countries. MATERIAL AND METHOD: We analyzed the demographic data on the Korean perfusionists conducted in 1994 and 2003, with comparison of recent data on the perfusionists of the nineteen foreign countries. RESULT AND CONCLUSION: Although all agree that professionalism and responsibility of the perfusionist are essential in conducting a cardiac procedure and bringing about successful outcome, the formally approved training and certification system for perfusionists have not yet been established in Korea. Adequate measures should be done as soon as possible in order to try to obtain the adequate recognition of the profession.

A case of patent ductus arteriosus in a holstein calf

This report describes a case of patent ductus arteriosus (PDA) which was found in a calf during an experiment on an implantable ventricular assist device. This is the first case report of PDA confirmed in the calf in Korea.

Biocompatibility of Tissue-Engineered Heart Valve Leaflets Based on Acellular Xenografts / 대한흉부외과학회지

BACKGROUND: Current artificial heart valves have several disadvantages, such as thromboembolism, limited durability, infection, and inability to grow. The solution to these problems would be to develop a tissue-engineered heart valves containing autologous cells. The aim of this study was to optimize the protocol to obtain a porcine acellular matrix and seed goat autologous endothelial cells on it, and to evaluate the biological responses of xenograft and xeno-autograft heart valves in goats. MATERIAL AND METHOD: Fresh porcine pulmonic valves were treated with one method among 3 representative decellularization protocols (Triton-X, freeze-thawing, and NaCl-SDS). Goat venous endothelial cells were isolated and seeded onto the acellularized xenograft leaflets. Microscopic examinations were done to select the most effective method of decellularizing xenogeneic cells and seeding autologous endothelial cells. Two pulmonic valve leaflets of 6 goats were replaced by acellularized porcine leaflets with or without seeding autologous endothelial cells while on cardiopulmonary bypass. Goats were sacrificed electively at 6 hours, 1 day, 1 week, 1 month, 3 months, and 6 months after operation. Morphologic examinations were done to see the biological responses of replaced valve leaflets. RESULT: The microscopic examinations showed that porcine cells were almost completely removed in the leaflets treated with NaCl-SDS. The seeded endothelial cells were more evenly preserved in NaCl-SDS treatment. All 6 goats survived the operation without complications. The xeno- autografts and xenografts showed the appearance, the remodeling process, and the cellular functions of myofibroblasts, 1 day, 1 month, and 3 months after operation, respectively. They were compatible with the native pulmonary leaflet (control group) except for the increased cellularity at 6 months. The xenografts revealed the new endothelial cell lining at that time. CONCLUSION: Treatment with NaCl-SDS was most effective in obtaining decellularized xenografts and facilitate seeding autologous endothelial cells. The xenografts and xeno-autografts were repopulated with myofibroblasts and endothelial cells in situ serially. Both of grafts served as a matrix for a tissue engineered heart valve and developed into autologous tissue for 6 months.

Biocompatibility and Histopathologic Changes of the Acellular Xenogenic Pulmonary Valved Conduit Grafted in the Right Ventricular Outflow Tract / 대한흉부외과학회지

BACKGROUND: The xenogenic or allogenic valves after in vitro repopulation with autologous cells or in vivo repopulation after acellularization treatment to remove the antigenicity could be used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellularized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. MATERIAL AND METHOD: Porcine pulmonary valved conduits were treated with NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson's trichrome staining and immunohistochemical staining was performed. RESULT: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory response was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet. CONCLUSION: The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulated cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.

Animal Experiments on an Antithrombogenic Small-Caliber Vascular Prostheses and Vascualr Patch: Observation in Canine Models / 대한흉부외과학회지

BACKGROUND: Although a variety of synthetic vascular grafts are available in modern vascular surgery, no ideal prosthesis has yet been developed. Small-caliber vascular grafts with low flow, as used in the lower extremity, continue to become thrombosed at unacceptable rates. We have developed and evaluated the new antithrombogenic blood contacting surfaces in canine model. MATERIAL AND METHOD: Two new antithrombogenic blood contacting surfaces(Polyvinylalcohol-Polyurethane(PVA-PU) blend and natural Graphite-Polyurethane(G-PU) blend) have been developed and evaluated in canine model, using vascular grafts and patches. The luminal surfaces of the test vascular grafts(5 mm ID) were fabricated by dipping a glass rod in PVA-PU blend solution(50 % PVA) using phaseseparation method. Mongrel dogs of either sex weighing 18-22 kg were anesthetized by endotracheal intubation using halothane and their lungs were ventilated with a volume-cycled ventilator. Maintenance anesthesia with 0.5-1.0% halothane and supplemental oxygen was used. Two pairs were used for comparison in the bilateral femoral arteries for both vascular grafts(PVA-PU vs. PU) and vascular patches(G-PU vs. PU). Bilateral groin incisions were made and the arteries were exposed and clamped. After an excision of 1 cm of the artery between clamps, a graft of 2.5 cm in length was implanted end-to-end using 6-0 polypropylene suture. The vascular patch was implanted as a form of on-lay patch. Animals were sacrificed at 1, 2, 4, 6, 8 and 16 weeks for vascular grafts and 1, 2, 4 and 6 weeks for vascular patches. RESULT: The vascular grafts of PVA-PU blends showed patent lumina in the 2 and 16 weeks animals, while those of PU showed a patent lumen in 2 weeks animal. PVA-PU graft of 16 weeks showed a fairly clean luminal surface. A light microscopic finding of this graft demonstrated good tissue infiltration through porosity. The animals with vascular patches showed patent arteries in both groups except 2 weeks animal. Scanning electron microscopy of the luminal surfaces of G-PU patches in 4 and 6 weeks animals showed endothelial cell covering with microvilli. PU patches showed qualitatively less endothelial cell covering. CONCLUSION:In conclusion, PVA-PU and G-PU blends can be a promising blood contacting surfaces for application in a synthetic vascualr graft. However,further animal study is needed to determine the real long-term effects of these methods of surface modifications.