• Journal of Chest Surgery
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• v.40 no.10
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• pp.659-666
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• 2007

Background: Preserving the subvalvular apparatus after mitral valve replacement (MVR) results in better ventricular function and a better outcome. In conjunction, mitral valve repair (MVr) is associated with a better outcome, yet little is known about the hemodynamics and outcomes between patients undergoing MVr and MVR with chordal preservation. We prospectively evaluated the hemodynamic changes and outcomes of patients undergoing MVr and MVR with chordal preservation. Material and Method: Fifty-four patients with mitral regurgitation (MR) who under-went MVR with chordal preservation (n=21) or MVr (n=33) were studied. The patients' characteristics, the intra-and postoperative hemodynamics and the use of cardiac medications, the postoperative outcome and the complications were recorded during the hospital stay. All the patients were followed up for at least 6 months post-operatively for determining their morbidity and mortality. Result: The patients' characteristics were similar between the groups, except for the presence of atrial fibrillation and congestive heart failure which was more frequent in the MVR group. Also, the preoperative left ventricular ejection fraction was lower in the MVR group than in the MVr group ($64{\pm}9%$ versus $69{\pm}5%$, respectively, p=0.043). There were no significant differences of the hemodynamics between the groups. The use of inotropic drugs and pacemakers during the 12hrs postoperatively was more common in the MVR group than in the MVr group (48% versus 24%, p=0.025 and 52% versus 24%, p=0.035, respectively). The other postoperative outcomes were similar in both groups for at least the 6 months follow-up period. Conclusion: MVR with chordal preservation was comparable with regard to the hemodynamics and clinical outcomes, supporting the beneficial effect of preserving the subvalvular apparatus after MVR.

• Journal of Chest Surgery
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• v.27 no.6
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• pp.460-471
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• 1994

Between Feb. 1990 and Aug. 1993, 180 cases of the open heart surgery were performed under cardiopulmonary bypass in the Department of Thoracic & Cardiovascular surgery, Gil General Hospital. There were 83 cases with congenital heart diseases [CHD] and 97 cases with acquired heart diseases [AHD]. The CHD consisted of 78 acyanotic[mortality: 3.8 %] and 5 cyanotic cases with heart anomaly[mortality:l case]. The AHD were 97 cases, which contained 53 valvular, 27 ischemic heart diseases, 10 aortic diseases, 5 cases with myxoma, 1 case with post-infarct VSD, and 1 case with removal of infected pacing wire in right ventricle. In the 53 valvular heart diseases, there were 45 cases with valve replacement[MVR 27, AVR 9,MVR + AVR 9] and 8 cases with valvuloplasty. The number of the implanted prosthetic valves were 53. In MVR, 25 St. Jude, 6 Sorin, 3 Carpentier-Edward and 2 Intact medical valves were used. In aortic position, 13 St. Jude, 3 Sorin and 1 Intact medical valves were applied. The operative mortality was 5.6 % [3/53]. The annuloplasty applying artificial ring was performed in 17 patients[4 cases associated with MVR] and the number of the implanted ring was 19, which included 14 Duran ring[10 mitral, 4 tricuspid] and 5 Carpentier ring [3 mitral, 22 tricuspid]. In the 27 ischemic heart diseases, there were 9 cases with left main coronary artery lesions, 7 one vessel, 5 two vessels, and 6 three vessels. Average number of anastomosis was 2.8 per patient. The operative mortality was 14.3 % [4/27]. Among the 10 patients with aortic diseases, 7 cases were aortic dissection[type A: 5, type B: 2] and 3 cases were descending thoracic aortic aneurysm. The operative morality occurred in 3 cases. The overall mortality and the operative mortality of congenital and acquired heart disease was 7.8 %, 4.8% and 10.4%, respectively.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.33-38
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• 2018

This study applied upgrades to the processes of a 10 MW wet amine $CO_2$ capture pilot plant and conducted performance evaluation. The 10 MW $CO_2$ Capture Pilot Plant is a facility that applies 1/50 of the combustion flue gas produced from a 500 MW coal-fired power plant, and is capable of capturing up to 200 tons of $CO_2$. This study aimed to quantitatively measure efficiency improvements of post-combustion $CO_2$ capture facilities resulting from process upgrades to propose reliable data for the first time in Korea. The key components of the process upgrades involve absorber intercooling, lean/rich amine exchanger efficiency improvements, reboiler steam TVR (Thermal Vapor Recompression), and lean amine MVR (Mechanical Vapor Recompression). The components were sequentially applied to test the energy reduction effect of each component. In addition, the performance evaluation was conducted with the absorber $CO_2$ removal efficiency maintained at the performance evaluation standard value proposed by the IEA-GHG ($CO_2$ removal rate: 90%). The absorbent used in the study was the highly efficient KoSol-5 that was developed by KEPCO (Korea Electric Power Corporation). From the performance evaluation results, it was found that the steam consumption (regeneration energy) for the regeneration of the absorbent decreased by $0.38GJ/tonCO_2$ after applying the process upgrades: from $2.93GJ/ton\;CO_2$ to $2.55GJ/tonCO_2$. This study confirmed the excellent performance of the post-combustion wet $CO_2$ capture process developed by KEPCO Research Institute (KEPRI) within KEPCO, and the process upgrades validated in this study are expected to substantially reduce $CO_2$ capture costs when applied in demonstration $CO_2$ capture plants.

• Journal of Chest Surgery
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• v.25 no.11
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• pp.1254-1260
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• 1992

Rupture of the posterior left ventricular wall following mitral valve replacement is a rare but fatal complication. Over a 10 year period from August 25 1980 to November 27 1990, we have experienced 6 such patients among 884 cases of mitral valve replacement with 4 deaths and 2 survivors. One patient had a type I rupture and another a type II rapture with the remaining four patients having suffered type III ruptures. All of the ruptures were dis covered intraoperatively enabling prompt reinstitution of the cardiopulmonary bypass and subsequent cardioplegic arrest prior to repair. Overzealous removal of calcified valve leaflets seemed to be responsible for the single type I rupture, and untethering of the so called ventricular loop appeared to be the main mechanism responsible for the type III ruptures. The single type II rupture that had occurred seemed to have been caused by inadvertent laceration of the papillary muscle with resultant rupture of the posterior LV wall at the base of the papillary muscle. Among the type III ruptures, 2 patients required intraaortic balloon pump[IABP] support only for mechanical assistance and 1 patient required both the IABP and the Biomedicus LV assist device for successfull weaning following repair of the LV rupture Another patient with a type II rupture also required the circulatory assistance of both the IABP and the bio-medicus LV assist device for weaning from the bypass. Attention to meticulous technical considerations such as avoiding over aggressive removal of heavily calcified valvular tissue, preservation of as much mural leaflet tissue and chordal stuctures as possible seemed helpful in preventing this catastrophic complication from occurring. Fusion and fibrous stricture of the chordal structures appeared particularly conducive to the type II ruptures as a result of the increased susceptibility to papillary injury during operation.

• Journal of Chest Surgery
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• v.38 no.11 s.256
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• pp.761-772
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• 2005

Background: Following the implantation of heart valve prostheses, it is important to maintain therapeutic INR to reduce the risk of thromboembolism. The objective of this study was to suggest a practical dosing guideline for Korean outpatients with prosthetic heart valves managed by a pharmacist-run anticoagulation service (ACS). Material and Method: A retrospective chart review was completed for all patients enrolled in the ACS at Seoul National University Hospital from March, 1997 to September, 2000. Patients who were at least 6 months post-valve replacement and had nontherapeutic INR value (less than 2.0 or greater than 3.0) were included. The data on 688 patients (1,782 visits) requiring dosing adjustment without any known drug or food interaction with warfarin were analyzed. The amount of adjusted dose and INR changes based on the INR at the time of the event were calculated. Aortic valve replacements (AVR) patients and mitral or double valve replacement (MVR/DVR) patients were evaluated separately. Result: Two methods for the warfarin dosage adjustment were suggested: Guideline I (mg-based total weekly dose (TWD) adjustment), Guideline II (percentage-based TWD adjustment). The effectiveness of Guideline 1 was superior to Guideline II overall in patients with both AVR and MVR/DVR. Conclusion: The guideline suggested in this study could be useful when the dosage adjustment of wafarin is necessary in outpatients with mechanical heart valves.

• Journal of Chest Surgery
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• v.30 no.10
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• pp.979-985
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• 1997

Between October 1991 and May 1995, 256 "New Duromedics Valve"(Edward TEKNA Bileaflet Valve) were implanted in 208 adult patients(171 mitral, 82 aortic and 3 tricuspid) with age ranging from 18 years to 70 years(mean 48.2$\pm$ 11.6 years). Postoperative complication rates were 12.2%, but there was none valve related one. Overall early mortality rate were 1.4%(1.6% for MVR, 2.1% for DVR, and none for AVR or TVR) respectively. Follow-up was 99% completed ranging in duration from 2 months to 46 months. There were 6 valve-related late complications(2.9%) with 2 patients with upper gastrointestinal bleeding, 2 with cerebral thxomtioembolism, 1 with valve thrombosis and 1 with valve endocarditis. Freedom from these valve-related major complications were 89.9% at 40 months. There were 5 late deaths(2.4%). one of these late deaths was considered valve-related. Overall actuarial survival rates at 40 months were 95.5%, 96.8% for mitral, 97.1% for aortic, 100% for tricuspid, and 92.0% for double valve replacement respectively. Preoperative New York Heart Association functional class were 2.9, and 1.3 in post-operative state. We have been trying to keep the international normalized ratio(INR) with range of 2.5 to 3.0. The INR of 4 patients of 5 with anticoagulant ralated complications was beyond the range. To reduce the rate of anticoagulant related complications, we felt very strongly that the INR should be kept between 2.5 and 3.0. In our cases, there was no structural failure or significant hemolysis in the absence of periprosthetic leak. This experience encourages us to continue using the "New Duromedics Valve".omedics Valve".uot;.