• Journal of Chest Surgery
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• v.29 no.10
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• pp.1111-1117
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• 1996

Structural deterioration of the bioprosthetic xenograft valves due to primary tissue failure occurs in two modes: from fatigue lesions with tear and wear with or without calcification and from calcification with obstruction. Two groups of consecutive 56 patients with the Hancock porcine ortic valve(HM) and of 1 13 patients with the standard-profile onescu-Shiley bovine pericardial valve(ISM) explanted from mitral position at the time of re-replacement surgery for primary tissue failure at Seoul national University Hospital until 1994, were studied for clinical and pathological features. Their ages at primary implant were 31.9 $\pm$9.2 years In HM and 30.4$\pm$ 12.5 years in ISM. Hemodrnamic dysfunction of the failed mitral bloprostheses were predominantly insufficiency in HM(64.3%) and stenosis in ISM(51.3%)(p<0.001). Pathologic findings of the explanted mitral valves reflected these hemodynamic changes, revealing failure more often from tissue damage(tears and wears) in HM and more often from calcification in ISM(p< 0.001). Explant period(from primary implant to explant) was relatively short in ISM(8.7$\pm$2.6years), compared with the one in HM(10.4 $\pm$2.6 years)(p<0.001). In conclusion, both the Hancock and the lonescu-shiley valves would fail from calcification as well as issue damage. However, while the Hancock porcine valves in mitral position failed more frequently from tissue failure and insufficiency, the standard-profile lonescu-Shiley pericardial valves did from calcification and stenosis, especially in young pAtients . Although the possibility of less occurrence of valve failure from mechanical reasons may be expected with newer generation bloprostheses, it does not seem to Improve durability significantly unless further refinement in antimineralization is achieved. Therefore, clinical use of the glutaraldehyde-treated bioprosthetic valves is, at present, limited to the patients of advanced age groups.

• Journal of Chest Surgery
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• v.49 no.5
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• pp.329-336
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• 2016

Background: Guidelines for esophagogastroduodenoscopy (EGD) in the West allow the continued use of warfarin under therapeutic international normalized ratio (INR) level. In Korea, no guidelines have been issued regarding warfarin treatment before EGD. The authors surveyed Korean cardiac surgeons about how Korean cardiac surgeons handle warfarin therapy before EGD using a questionnaire. Participants were requested to make decisions regarding the continuation of warfarin therapy in two hypothetical cases. Methods: The questionnaire was administered to cardiac surgeons and consisted of eight questions, including two case scenarios. Results: Thirty- six cardiac surgeons at 28 hospitals participated in the survey, and 52.7% of the participants chose to stop warfarin before EGD in aortic valve replacement patients without risk factors for thromboembolism. When the patient's INR level was 2, 31% of the participants indicated that they would choose to continue warfarin therapy. For EGD with biopsy, 72.2% of the participants chose warfarin withdrawal, and 25% of the participants chose heparin replacement. In mitral valve replacement patients, 47.2% of the participants chose to discontinue warfarin, and 22.2% of the participants chose heparin replacement. For EGD with biopsy in patients with a mitral valve replacement, 58.3% of the participants chose to stop warfarin, and 41.7% of the participants chose heparin replacement. Conclusion: This study demonstrated that attitudes regarding warfarin treatment for EGD are very different among Korean surgeons. Guidelines specific to the Korean population are required.

• Journal of Chest Surgery
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• v.47 no.4
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• pp.333-343
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• 2014

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.

• Journal of Chest Surgery
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• v.41 no.3
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• pp.295-304
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• 2008

Background: Various experimental trials for the development of bioprosthetic devices are actively underway, secondary to the limited supply of autologous and homograft tissue to treat cardiac diseases. In this study, porcine bioprostheses that were treated with glutaraldehyde (GA), ethanol, or sodium dodecylsulfate (SDS) were examined with light microscopy and transmission electron microscopy for mechanical and physical imperfections before implantation, Material and Method: 1) Porcine pericardium, aortic valve, and pulmonary valve were examined using light microscopy and JEM-100CX II transmission electron microscopy, then compared with human pericardium and commercially produced heterografts. 2) Sections from six treated groups (GA-Ethanol, Ethanol-GA, SDS only, SDS-GA, Ethanol-SDS-GA and SDS-Ethanol-GA) were observed using the same methods. Result: 1) Porcine pericardium was composed of a serosal layer, fibrosa, and epicardial connective tissue. Treatment with GA, ethanol, or SDS had little influence on the collagen skeleton of porcine pericardium, except in the case of SDS pre-treatment. There was no alteration in the collagen skeleton of the porcine pericardium compared to commercially produced heterografts. 2) Porcine aortic valve was composed of lamina fibrosa, lamina spongiosa, and lamina ventricularis. Treatment with GA, ethanol, or SDS had little influence on these three layers and the collagen skeleton of porcine aortic valve, except in the case of SDS pre-treatment. There were no alterations in the three layers or the collagen. skeleton of porcine aortic valve compared to commercially produced heterografts. Conclusion: There was little physical and mechanical damage incurred in porcine bioprosthesis structures during various glutaraldehyde fixation processes combined with anti-calcification or decellularization treatments. However, SDS treatment preceding GA fixation changed the collagen fibers into a slightly condensed form, which degraded during transmission electron micrograph. The optimal methods and conditions for sodium dodecylsulfate (SDS) treatment need to be modified.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.627-634
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• 2010

Background: The durability of the tissue valve is important in choice between a mechanical valve and a tissue valve in cardiac surgery. We studied the mid-term results of tissue valve in the aortic position. Material and Method: The subjects were 380 patients who had undergone aortic prosthesis replacement between May 1990 and March 2009. We retrospectively analyzed hospital and outpatient records: the mean age was $69{\pm}9$ years; the male to female ratio was 227 : 162; and the mean follow-up duration was $46.7{\pm}40.8$ months (range 0~196 months). Result: 389 surgical cases in total had been taken with 380 patients. Early death occurred in 15 patients (3.9%). Overall survival rate at 1, 5 and 10 years were 92.3%, 78.1% and 54.2% respectively. Freedom from reoperation at 1, 5 and 10 years were 98.4%, 97.1% and 91.7% respectively. Freedom from structural valvular deterioration at 1, 5 and 10 years were 96.1%, 92.3% and 88.0% respectively. In the multivariate analysis of preoperative risk factors, young age (p<0.001) was significant risk factor for reoperation. High peak velocity in the postoperative period (p=0.034) and young age (p=0.029) were significant risk factors for structural valvular deterioration. Old age (p=0.001), long bypass time (p=0.035), concomitant coronary artery bypass graft surgery (p=0.003) and preoperative low left ventricular ejection fraction (p=0.003) were significant factors for early mortality. Preoperative estimated glomerular filtration rate (< 60 mL/min) (p=0.025) and persistent left ventricular hypertrophy (p=0.032) were the risk factors for late mortality. Conclusion: This study showed that the freedom from reoperation and the freedom from structural valvular deterioration in aortic tissue valve replacement were acceptable. It will be necessary to conduct further studies with long-term follow-up and more patients.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.614-618
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• 2010

Background: The aim of our study was to assess the extent of regression of left ventricular mass after aortic valve replacement in isolated aortic regurgitation. Material and Method: Retrospective analysis of echocardiographic data was collected preoperative and postoperative 1 year. There were 20 patients (12 males, 8 females, mean age $55.8{\pm}11.8$ years, mean body surface area $1.64{\pm}0.19m^2$) with aortic regurgitation from 2002 through 2007. We studied the change of left ventricular ejection fraction, ventricular septum and left ventricular posterior wall thickness, and left vemtricular muscle index (LVMI). The control group was age matched with normal echocardiographic study results. Patients with combined surgery or infective endocarditis were excluded. Result: Seven cases of tissue valves and thirteen cases of mechanical valve were used. The valve sizes were 21 mm (3 cases), 23 mm (13 cases) and 25 mm (4 cases). The postoperative ($125.5{\pm}42g/m^2$) LVMI has decreased than preoperative LVMI ($212.3{\pm}80g/m^2$, p=0.000) but higher than that of control group ($80.5{\pm}15.9g/m^2$, p=0.000). Postoperative septal wall (systolic/diastolic: $13.5{\pm}3.4mm/17.1{\pm}4.1mm$) and left ventricular posterior wall (systolic/diastolic: $12.9{\pm}3.4mm/16.7{\pm}3.4mm$) thickness were slightly decreased after the valve replacement but was not significantly different than preoperative levels. And postoperative interventricular septal wall and left ventricular posterior wall thickness (systolic/diastolic: $8.6{\pm}1.4mm/12.1{\pm}1.7mm$, systolic/diastolic: $8.4{\pm}1.4mm/13.2{\pm}1.9mm$) were higher than that of the control group (p<0.001). Conclusion: The significant regression of LVMI after aortic valve replacement developed at postoperative one year but the level was higher than control group. The main cause of decreased LVMI is decreased in left ventricular dimension.

• Journal of Chest Surgery
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• v.21 no.6
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• pp.979-983
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• 1988

Calcium channel blockers may prevent myocardial injury during cardioplegia and reperfusion. This study was done to evaluate the effects of diltiazem cardioplegia on myocardial protection during ischemic arrest and recovery of myocardial function after reperfusion. Four formulations of crystalloid cardioplegic solutions, GIK solution[group I, n=12], diltiazem[lug/ml GIK] in GIK solution[group II, n=7], ],diltiazem[2ug/ml GIK] in GIK solution[group III, n=6] and diltiazem[4ug/ml GIK] in GIK solution[group IV, n=6] were compared in isolated working rat heart subjected to a long period [2 hours] of hypothermic arrest with multi-dose infusion. Diltiazem cardioplegia[group II, III and IV]was found to be superior in nearly all aspects. Diltiazem cardioplegia showed faster recovery of regular rhythm and lower incidence of ventricular fibrillation than group I did. In comparing mechanical function in all experimental hearts, the mean postischemic recoveries of aortic flow, cardiac output, peak aortic pressure, stroke volume and stroke work[expressed as a percentage of its preischemic control] were significantly greater in group II, III and IV[diltiazem cardioplegia] than in group I. The infused amount of cardioplegic solution was more increased by the addition of diltiazem to GI K solution. [p < 0.01] Creatine kinase leakage tended to be lower in hearts receiving diltiazem cardioplegia, especially in group III and IV[p<0.05] than in those receiving GIK solution only[group I]. Diltiazem cardioplegia results in the increased flow of cardioplegic solution and the decreased ischemic injury of myocardium during ischemic arrest and the improved recovery of myocardial function after reperfusion, and a dose-response relation must be established before clinical use.

• Journal of Chest Surgery
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• v.36 no.4
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• pp.273-276
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• 2003

We report a surgical case of 39-year-old male with a pseudoaneurysm of the left ventricle. Four years ago, the patient underwent aortic and mitral valve replacements with mechanical valves and abscess removal for infective endocarditis with annular abscess. Recent echocardiography demonstrated a communication between left ventricle and abscess pocket, and the size of pocket increased further at the follow-up echocardiography. The patient underwent patch closure of the defect between left ventricle and pseudoaneurysm located at the aortomitral fibrous continuity, under the cardiopulmonary bypass and cardioplegia. The postoperative course was uneventful and the patient was discharged on the 9th postoperative day.

• Journal of Chest Surgery
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• v.42 no.3
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• pp.317-323
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• 2009

Background: Although high efficiency of conversion into sinus rhythm has been demonstrated after performing the Cox-Maze procedure in patients with atrial fibrillation associated with mitral valve disease, the changes in the mechanical function and size of the left atrium have not been determined. The aim of the study was to evaluate the effect of the Maze procedure on the left atrial size and contractile transport function. Material and Method: From July 1997 to July 2008, 647 consecutive patients were operated on for chronic atrial fibrillation associated with mitral valve disease. Among these, 211 patients that (1) were able to be followed up for 2 years after surgery, (2) had sustained normal sinus rhythm, regardless of whether they were taking anti-arrhythmic medications and (3) did not have valvular regurgitation greater than grade III or they did not have moderate grade valvular stenosis were selected for evaluation. The left atrial size and contractile transport function were assessed by transthoracic echocardiography at the postoperative base line (1 year) and at regular follow-up periods (2 years, 3 years, 4 years and 6 year). Result: The left atrial dimension was increased and the contractile transport function was decreased during the follow-up period. The longer the follow-up period, the greater was the statistical significance of the left atrial size increase and contractile transport function decrease. Conclusion: In patients who sustain normal sinus rhythm conversion after a Maze III procedure with a mitral valve operation, there is a gradual increase of the left atrial dimensions and a decrease of contractile transport function during the follow-up period. Therefore, scrupulous follow-up is needed for these patients.

• Journal of Chest Surgery
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• v.42 no.5
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• pp.566-575
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• 2009

Background: The function of a bioprosthetic heart valve is determined largely by the material properties of the valve cusps. The uniaxial tensile test has been studied extensively. This type of testing, however, does not replicate the natural biaxial loading condition. The objective of the present study was to investigate the regional variability of the biaxial strain versus pressure relationship based on the types of fixation liquid models. Material and Method: Porcine aortic valves and pulmonary valves were assigned to three groups: the untreated fresh group, the fixed with glutaraldehyde (GA) group, and the glutaraldehyde with solvent (e.g., ethanol) group. For each group we measured the radial and circumferential stretch characteristics of the valve as a function of pressure change. Result: Radial direction elasticity of porcine aortic and pulmonary valves were better than circumferential direction elasticity in fresh, GA fixed and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of pulmonary valves were better than aortic valves in GA fixed, and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of aortic valves were decreased after GA and GA+solvent fixation(p=0.00), except for circumferential elasticity of GA+solvent fixed valves (p=0.785). The radial (p=0.137) and circumferential (p=0.785) direction of elasticity of aortic valves were not significantly different between GA fixed. and GA+solvent fixed groups. Radial (p=0.910) and circumferential (p=0.718) direction of elasticity of pulmonary valve also showed no significant difference between GA fixed and GA+solvent fixed groups. Conclusion: When fixing porcine valves with GA, adding a solvent does not cause a loss of mechanical properties, but, does not improve elasticity either. Radial direction elasticity of porcine aortic and pulmonary valves was better than circumferential direction elasticity.