• Journal of Chest Surgery
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• 제9권2호
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• pp.198-206
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• 1976

A Total of Forty eight patients underwent open-heart surgery for correction of tetralogy of Fallot at the Seoul National University Hospital from January 1974 to October 1976, with an overall survival rate of 77 per cent. Operative mortality varied according to severity of the lesion, age of the patient, nature of previous surgical treatment and presence or absence of an outflow tract patch across the pulmonary valve ring. Eleven patients died in the early postoperative period and thirty seven patients were discharged from the hospital alive. A patch of the right ventricular outflow tract and pulmonary annulus was required to relieve pulmonic stenosis in 24 patients. There were 10 deaths in this group (42%) as compared to 1 death in the group of 24 patients who were corrected without a patch. Operative mortality was especially higher when an inlay patch was placed across the pulmonary valve ring. This may be related to the possibly greater anatomic severity of these cases and to the longer operating time when a patch was used. The electrocardiogram showed right ventricular hypertrophy in 35 cyanotic patients. Intraventricular conduction was normal in 34 patients before operation. It was normal postoperatively in only 5 of 34 patients in this group who survived surgery. Complete right bundle branch block appeared at operation in 21 patients, and 8 patients developed incomplete right bundle branch block. Major causes of death were progressive cardiac failure (4), Complete atrioventricular dissociation (3), bleeding (2), cardiac tamponade (1), and sudden cardiac arrest (1)

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.69-77
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• 2011

A peristaltic micropump with lightweight piezo-composite actuator (LIPCA) membrane valves is presented. The micropump contained three cylinder chambers that were connected by microchannels and two active membrane valves. A circular miniature LIPCA was developed and manufactured to be used as actuating diaphragms. The LIPCA diaphragm acted as an active membrane valve that alternate between open and closed positions at the inlet and outlet in order to produce high pumping pressure. In this LIPCA, a lead zirconium titanate ceramic with a thickness of 0.1 mm was used as an active layer. The results confirmed that the actuator produced a large out-of-plane deflection. During the design process, a coupled field analysis was conducted in order to predict the actuating behavior of the LIPCA diaphragm; the behavior of the actuator was investigated from both a theoretical and experimental perspective. The active membrane valve concept was introduced as a means for increasing pumping pressure, and microelectromechanical system techniques were used to fabricate the peristaltic micropump. The pumping performance was analyzed experimentally in terms of the flow rate, pumping pressure and power consumption.

• Journal of Chest Surgery
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• 제35권2호
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• pp.102-112
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• 2002

This study was undertaken to analyze the outcome of composite valve graftreplacement(CVGR) for the treatment of aneurysms of the ascending aorta involving the aortic root. Material and Method: Between April 1995 and June 2001, 56 patients had replacement of the ascending aorta and aortic root with a composite graft valve and were reviewed retrospectively. Aortic regurgitation was present in 50 patients(89%), Marfan's syndrome in 18 patients(32%), and bicuspid aortic valve in 7(12.5%). The indications for operation were annuloaortic ectasia(AAE) in 30 patients(53.6%), aortic dissection in 13(23.2%), aneurysms of the ascending aorta involving aortic root in 11(19.6%), and aortitis in 2(3.6%). Cardiogenic shock due to the aortic rupture was present in 2 patients. Nine patients(16%) had previous operations on the ascending aorta or open heart surgery. The operative techniques used for CVGR were the aortic button technique in 51 patients(91%), the modified Cabrol technique in 4, and the classic Bentall technique in 1. The concomitant procedures were aortic arch replacement in 24 patients(43%), coronary artery bypass graft in 8(14.3%), mitral valve repair in 2, redo mitral valve replacement in 1, and the others in 7 The mean time of circulatory arrest, total bypass, and aortic crossclamp were 21$\pm$14 minutes, 186$\pm$68 minutes, and 132$\pm$42 minutes, respectively. Result: Early mortality was 1.8%(1/56). The postoperative complications were left ventricular dysfunction in 16 patients(28.6%), reoperation for bleeding in 7(12.5%), pericardial effusion in 2, and the others in 7. Fifty-three patients out of 55 hospital survivors were followed up for a mean of 23.2 $\pm$ 18.7 months(1-75 months). There were two late deaths(3.8%) including one death due to the traumatic cerebral hemorrhage, and CVGR-related late mortality was 1.9%. The 1- and 6-year actuarial survival was 98.1$\pm$1.9% and 93.2$\pm$5.1%, respectively. Two patients required reoperation for complication of CYGR(3.8%) and two other patients required subsequent operations for dissection of the remaining thoracoabdominal aorta. The 1- and 6-year actuarial freedom from reoperation was 97.8$\pm$2.0% and 65.3$\pm$26.7%, respectively.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.373-378
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• 2000

The crevice corrosion of local corrosion occur when the gap exist on metal surface. This crevice corrosion happen to region such as flange of pipe, contact part of casing, under gasket and packing, between valve disk and seat of pump etc. Especially The crevice corrosion of mild steel(SS 400) get serious. This paper was studied on the crevice corrosion of SS 400 in fluid environment. In $0\%,\;2\%,\;3.5\%,\;5\% NaCl$ solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by $3.5\%$ but the concentration increased over $3.5\%$, the current density was low drained. 3) The weight loss rate of SS 400 was increased as concentration of NaCl solution Increased by $3.5\%$, but the concentration increased over $3.5\%$, that of SS 400 was decreased. 4) Effect of oxygen for crevice corrosion in the concentration of $3.5\%$ NaCl solution become sensitive than that $0\%$ NaCl solution.

• Journal of Chest Surgery
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• 제22권4호
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• pp.609-619
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• 1989

During aortic valve surgery, cardioplegic solution is delivered through direct cannulation of both coronary ostia. Since this approach may cause an intimal injury leading to acute dissection or late ostial stenosis, this study was undertaken to evaluate myocardial protective effect of retrograde perfusion of cardioplegia [RCSP <% RRAP] in 18 clinical cases, which were compared with antegrade perfusion of cardioplegia in 27 clinical cases. This study were investigated 1] cease and return of electromechanical activity after cardioplegia infusion 2] the myocardial temperature during operation 3] the aortic cross clamping time and total bypass time 4] frequency of DC shock for defibrillation 5] need for inotropic drugs after operation 6] electrocardiographic evidence of myocardial infarction or ventricular arrhythmia after operation 7] the enzymes activity during preoperative and postoperative period as an evaluation of myocardial ischemic injury and 8] operative mortality rate The combination of retrograde cardioplegia and topical cooling with ice slush yielded promptly hypothermia of myocardium and shorter aortic cross-clamping time compared with antegrade cardioplegia [P < 0.05]. The temperature of the interventricular septum was maintained below 20oC by continuous perfusion or intermittent perfusion of cold blood cardioplegia and other results were no statistically significant difference between the two methods [P >0.05]. This technique provides clear operative field and avoids some serious complications which are caused by coronary ostial cannulation. These results suggested that the retrograde perfusion of cardioplegia is a simple, safe, and effective means of myocardial protection during open heart surgery.

• Journal of Chest Surgery
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• 제30권5호
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• pp.506-511
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• 1997

To understand the clinical results of aortic root replacement with either inclusion or open technique, we analysed 53 patients who underwent replacement of the aortic root with composite graft between October,1980, and May, 1995. Annuloaortic ectasia was the most common indication for operation(29 patients), follwed by aortic dissection(22 patients). Among 53 patients, 19(35%) had Marfan syndrome. Three patients died during hospitalization (Mortality: 5.5%). The follow up was possible in 48 patients(Follow-up rate; 94%,mean duration;37 months). The actuarial survival rate at 24 months was 95% in open technique group, and 87% in inclusion technique group. Late complications developed in 10 patients. Dissecting aneurysm in the remaining aorta was noted in 3 patients with inclu ion 1,schnique, and a pseudoaneurysm from coronary artery anastomosis site developed in a patient with inclusion technique. In conclusion, there was no statistical differences in survival for 24 months between inclusion technique and open technique group. But late problems in the remaining aorta or death from unknown cause occurred with moderate frequency : careful follow-up after aortic root replacement thought to be important for long term survival.

• Journal of Chest Surgery
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• 제18권4호
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• pp.598-604
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• 1985

One hundred consecutive patients with the Tetralogy of Fallot underwent total correction at National Medical Center during the period 1977 to 1984, Oct. During this study period, we adopted more active policy towards reconstruction of right ventricular outflow tract across pulmonary valve. The mortality was 48% for patients less than 15 kg and 19% in patients above 15kg. Initially Bretschneider`s solution was used as cardioplegia, which was replaced by St. Thomas` solution since 1983, Jan. After then overall mortality dropped to 9% compared to 45% of initial learning period. Heart block occurred In 11 patients, 10 of whom died of combined low cardiac output syndrome. Pure low cardiac output syndrome was noted in 18 patients, most of whom responded to medical measures well except 4 patients. Recently sepsis of Serratia marcescence, which occurred explosively during several months to open heart surgery patients, attacked 3 tetralogy patients resulting in 2 hospital deaths. Our experience has shown that body weight, choice of cardioplegia and accumulation of experience as well as advance of operative and postoperative techniques are still important factors affecting survival rate at initial learning period.

• Transactions of the Korean Society of Automotive Engineers
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• 제5권4호
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• pp.1-20
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• 1997

The automotive industry as the major industry of the nation has affected both society and economy since the automobile was invented, and the main technique that help to performance improvement of the automobile has been developed. But, the painting technique lags behind the main technique of the automobile because that was neglected. Specially, we can say that in case of the painting technique of the automobile of our nation is so weak situation. After we changed the injecting pressure, the composition ratio (paint, hardener, thinner) and the injecting flow rate from spray-gun by PDPA, we studied the character of the injecting velocity and droplet size, and found the fittest condition. So, we got the following result to help mending paint technique of automobile surface. We could know the following fact from the experiment result. When it does mending paint of automobile, there is most suitable that to inject the paint as injecting pressure 200∼300 kPa and to inject the ratio of paint 10 : 1 : 1 when the fluid adjective knob valve spay-gun is open full.

• Journal of Chest Surgery
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• 제10권2호
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• pp.299-314
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• 1977

Clinical experience on 16 cases of open heart surgery under the extracorporeal circulation with mild or moderate hypothermia and partial hemodilution technique at the National Medical Center during the period from June 1976 to October 1977. Nine of sixteen were congenital heart disease and seven were acquired heart disease. The age of the patient ranged between 6 and 48 years. The body weight varied from 18.5kg to 60kg and body surface area 0. 79-1.70m2. The average priming volume of pump oxygenator was 2080 ml, which was consisted fresh ACD blood, buffered Hartmann`s solution, Mannitol, 50% dextrose in water and Vit. C. The average hemodilution rate was 27%. The average flow 2.3 L/min/m2 or 80 ml/min and the duration of perfusion varied from 31 min to 270 min with average of 107 min. The perfusion was carried out under the mild or moderate hypothermia using core cooling alone in 10 cases, core cooling and local myocardial cooling with $0-4^{\circ}C$ physiologic saline in 2 cases. From a hemodynamic point of view, the blood pressure dropped down around 80 mmHg after the initiation of perfusion follwed by increase to safety level and stable during the perfusion. The central venous pressure remained within normal limits. In most cases, hemoglobin and hematocrit decreased during and after the perfusion. Hemogiobin level was decreased, average of 20.6 %, hematocrit 18.6%, pletelets 55% postoperatively. Plasma hemoglobin increased moderately, from preperfusion average valve of 7.79 mg % to post-perfusion value of 54.7 mg %. Electrolytes changes during cardiopulmonary bypass showed definite hypokalemia but changes of Na, Ca were not definite. Arterial blood gas analysis during cardiopulmonary bypass suggested that the metabolic acidosis which was accompanied by respiratory alkalosis which was corrected postoperatively. As the opera tive complication, transient hemoglobinuria in 4 cases and neurological signs in 2 cases were all cured. There were 2 death cases and operative mortality rate was 12.5%.

• Journal of Chest Surgery
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• 제32권11호
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• pp.1017-1022
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• 1999

Background: An increasing number of elderly are referred for open heart surgeries(OHS). These patients are assumed to have significantly increased morbidity and mortality because of compromised functional reserves in their vital organs. We reviewed the results of OHS patients who were 70 years old or older. Material and Method: Thirty six consecutive septuagenarians underwent OHS from 1995 to 1997. Operations were coronary artery bypass grafting(CABG) in 26 including 3 left main surgical angioplasty, valve replacement in 7, MVR+CABG in 2, and ASD closure+TAP in 1. Statistical tests were carried out to compare survivor group with nonsurvivor group in respect to risk factors including NYHA functional class, LVEF, emergent operation, IABP support, CPB/ACC time, ventilator time cardiac index, ICU stay and hospital stay for operative mortality. Result: Operative mortality rate and postoperative complication were 16%(6/36) and 50%(18/36). One-year and 3-year actuarial survival rates were 76%. Nine patients(25%) had major complications including third-degree A-V block(2), respiratory failure(1), stroke(3), renal failure requiring dialysis(3) and postoperative hemorrhage(2). The causes of death were pneumonia(1), bleeding(1), acute renal failure(1), low cardiac output(1), third-degree A-V block(1), and ventricular tachycardia(1). The univariate analysis of mortality shows that NYHA class IV, LVEF<40%, lesser values for C.I, and longer time for ventilatory support were associated with the risk factors(p value=0.03, 0.001, 0.007, and 0.014). The emergent operation, CPB/ACC time, IABP support, ICU stay and hospital stay were not significant. Conclusion: We conclude that cardiac operation can be performed in septuagenarians with acceptable outcomes when done in patients with normal to moderately depressed left ventricular function and adequate functional reserves in their vital organs.