• Korean Journal of Clinical Pharmacy
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• v.9 no.1
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• pp.27-34
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• 1999

The goal of oral anticoagulation therapy with warfarin is to maintain INR values within the therapeutic range in order to prevent complications such as bleeding and thrombosis. The purposes of this study were to investigate the current level of anticoagulation control using INR values, to investigate the incidences of thromboembolism and bleeding complications, and to compare the effect of low intensity INR regimen with therapeutic range recommended by ACCP (American College of Chest Physician). Two hundred three patients with mechanical heart valve replacement done at Yonsei University Cardiovascular Center between January 1994 and December 1996 were selected and reviewed retrospectively. The target INR ranges of $2.5\sim3.5$ (ACCP standard) and low intensity INR of $2.0\sim3.5$ were used for evaluation. According to ACCP standard, $51.2\%$ of patients and $31.1\%$ of INR values were within the therapeutic range when average INR and cumulative INR were used, respectively. Applying low intensity INR values of $2.0\sim3.5$, the therapeutic control was achieved in $57.4\%\;and\;90.1\%$, using average INR and total INR, respectively. The incidences of major and minor bleedings were $0.5\%\;and\;26.6\%$, respectively. The incidence of thromboembolism was $0.5\%$. There was no significant difference in terms of complication incidences between INR $2.0\sim2.5\;and\;INR\;2.5\sim3.5$ groups. However, INR values at the time of bleeding were generally high. In conclusion, the evaluation of patients with mechanical heart valve replacement showed low level of therapeutic control with warfarin therapy. This is partially explained by the fact that the physicians at Yonsei University Cardiovascular Center were using lower intensity INR values as a goal than recommended INR. Also, in the near future, systematic anticoagulation service should be implemented at various hospitals in Korea so that patients on anticoagulant therapy can be more closely monitored to be within the recommended INR by ACCP.

• Journal of Korean Academy of Nursing
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• v.45 no.4
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• pp.554-564
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• 2015

Purpose: The purpose of this study was to develop and evaluate a self-management program based on INR monitoring for patients with cardiac valve replacement. Methods: This program was comprised of five weekly sessions based on Sousa's Enhance-Behavior Performance Model. The first session included individual teaching, and the other four sessions included Prothrombin Time International Normalized Ratios (PT INR) self-monitoring, telephone counseling and self-management checklist recording. Participants were patients who had cardiac valve replacement. They were randomly assigned to the experimental or control group. Sixteen in the experimental group participated in the self-management program and seventeen in the control group participated in general care. Self-management knowledge, self-efficacy, self-management behavior and PT INR were measured as dependent variables. Data were analyzed using Mann Whitney U-test, t-test and ANCOVA. Results: The experimental group showed significantly higher post-test scores in self-management knowledge (t=5.86, p<.001), self-efficacy (F=18.32, p<.001), and self-management behavior (t=3.44, p=.002) compared to the control group. Also, the experimental group showed significantly higher frequency in maintaining the treatment range of PT INR compared to the control group (${\chi}^2=4.80$, p=.028). Conclusion: The results of the research on the self-management program based on PT INR monitoring showed that it is effective in improving self-management knowledge, self-efficacy, and self-management behavior as well as maintaining treatment range of PT INR of patients with cardiac valve replacement.

• The Journal of Internal Korean Medicine
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• v.28 no.3
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• pp.464-472
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• 2007

Objectives : Nowadays the combined use of oriental herbal medicines and western biomedical medicines has been prevalent but controversial. Warfarin has been much reported to interact with some herbal medicines so that it influences prothrombin time(PT) & international normalized ratio(INR). This study was aimed to examine how much warfarin interacts with herbal medicines during treatment of stroke patients Methods : This was a retrospective case control study of 53 patients whowere treated with concomitant treatment of herbal medicines & warfarin. They were within normal limit in liver function, renal function, hematocrit, hemoglobin, and platelet count at first admission lab. We classified them into 2 classes: study group (taking herbal medicines including Panax ginseng, Angelica sinensis, Zingiber officinale, Salvia miltiorrhiza that were reported to interact with warfarin to impact PT (INR) and control group (taking other herbal medicines). We followed up PT (INR) at 5-10 days interval with AST, ALT, BUN, creatinine, hematocrit, hemoglobin, and platelet count. Results : AST, BUN, creatinine, hemoglobin, hematocrit, and platelet count were not changed significantly between first and final tests during the admission period. Only ALT decreased significantly in the control group. Neither baseline nor peak PT (INR) was significantly different between the groups. However, only warfarin dose was significantly correlated with PT and INR (r=0.810, r=0.798, p<0.01). Conclusions : It was concluded that PT(INR) was not influenced with herbal medicines and warfarin but by far dependent on warfarin dose in stroke patients restricted with normal liver function, renal function, and hematocrit, hemoglobin, and platelet count. Further prospective study is needed on larger samples to conclude that the combined therapy of herbal medicines and warfarin is safe.

• Korean Journal of Clinical Pharmacy
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• v.5 no.2
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• pp.17-31
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• 1995

Pharmacist-managed Anticoagulation Service(ACS) was estabilished and the effectiveness of warfarin monitoring by ACS in maintaining therapeutic INR was evaluated. The primary goal of ACS is to maximize the control of therapy, to maintain therapeutic INR and to decrease morbidity and hospitalization caused by inadequate dosage regimen. Clinical pharmacists performed chartreview, laboratory interpretation, recommendations for warfarin dosage adjustments, physician and patient education, and coordination of follow-up in ACS. Patients receiving warfarin sodium were evaluated via retrospective chart review. Sixty-two patients were referred to ACS by primary physicians were compared with 117 patients in the physician-amtrolled group. The ACS patients maintained $88.6\%$ in the therapeutic range for anticoagulant therapy and the control group maintained $63.7\%$, where the difference was statistically significant.(P<0.001) The ACS improved warfarin dose determination, PT stability, patient compliance and provided improved therapy compared with the control group. ACS offers safe and efficient anticoagulant therapy in the ambulatory setting.

• Journal of Power Electronics
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• v.12 no.1
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• Journal of Chest Surgery
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• v.31 no.12
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• pp.1172-1182
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• 1998

Background: Primary goal of anticoagulation treatment in patients with mechanical heart valve is the effective prevention of thromboembolism and safe avoidance of bleeding as well. Material and Method: Two-hundred and nine patients with the St. Jude Medical prosthesis operated on between 1984 and 1995, for mitral(MVR 122), aortic(AVR 39) and double mitral and aortic valve replacement(DVR 48) respectively, were studied on the practically achieved levels of anticoagulation and the clinical outcomes. Patients were on Coumadin and followed up by monthly visit to outpatient clinic for examination and prothrombin time measurement to adjust the International Normalized Ratios(INRs) within the low-intensity target range between 1.5 and 2.5. Result: A total anticoagulation follow-up period was 1082.0 patient- years(mean 62.1 months) and INRs of 10,205 measurements were available for evaluation. The accomplished INRs among the replacement groups were not significantly different and only 65% of INRs were within the target range. And, in individual patients, only 37% of patients had INRs included within the target range in more than 70% of tests during follow-up period. The levels of INRs in patients with atrial fibrillation, which was found in 57% of patients, were definitely higher than the ones measured in patients with regular rhythm(p<0.001). Thromboembolisms were experienced by 15 patients with the incidence of 1.265%/patient- year(MVR 1.412%, AVR 0.462% and DVR 1.531%/patient-year) and major bleeding by 4 patients with the incidence of 0.337%/patient-year(MVR 0.424%, AVR none and DVR 0.383%/patient-year). Frequent as well as prolonged missing of prothrombin time tests was the main risk factor strongly associated with the thromboembolic complications(odds ratio 1.99). The proportion of INRs within target range of less than 60% in individual patient was the highly significant risk factor of both thromboembolic and overall embolic and bleeding complications(p<0.004 and p<0.002 respectively). Conclusion: In conclusion, the low-intensity therapeutic target range of INRs was adequate in patients with AVR and in sinus rhythm. However, the patients with replacement of the mitral valve were more likely to require higher target range of INRs, especially in the presence of atrial fibrillation, to achieve the practical levels of anticoagulation enough to prevent thromboembolic complications effectively. For the higher therapeutic target range of INRs between 2.0∼3.0, further accumulation of clinical evidences are required. It is highly desirable to improve the patients' compliance under continuous instructions in visiting outpatient clinic and in taking daily Coumadin without omission and to keep INRs consistently within optimal range with tight control for minimization of chances and of periods of exposure to the risk of complications. And, particularly, patients with high risk of complications and with wide fluctuation of INRs should be better managed with frequent monitoring anticoagulation levels.

• Biomolecules & Therapeutics
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• v.14 no.4
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• pp.189-193
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• 2006

This study was designed to assess the distribution of cytochrome P450 2E1 (CYP2E1) polymorphism among Korean patients on warfarin therapy. CYP2E1 polymorphism was analyzed at 5' flanking region of CYP2E1 gene using restriction fragment length polymorphism method. Patient characteristics including the measured internal normalized ratio (INR) were also evaluated. Based on the warfarin dose and the bleeding cases, the patients were grouped as the regular dose control, the regular dose bleeding, the low dose control, and the low dose bleeding. Total 96 patients were evaluated for both Pst I and Rsa I loci of the CYP2E1 gene and the results showed that both loci were tightly linked. Thirty-three patients(34.4%) were heterozygotes and 4 patients(4.2%) were homozygote. There was no significant difference in patient characteristics in the dose and bleeding case groups. CYP2E1 polymorphism showed a little difference among the groups but was not statistically significant, however, lower INR value was observed in homozygote genotype groups. It was also revealed that genotype allele frequencies of CYP2E1 in Korean was close to other Asian groups but was significantly different from other Caucasian and African-American populations.

• Journal of Chest Surgery
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• v.54 no.1
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• pp.25-30
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• 2021

Background: Life-long anticoagulant therapy is mandatory for patients who undergo heart valve replacement with implantation of a mechanical prosthesis. The aim of this study was to investigate the effects of a nurse-led patient educational program concerning oral anticoagulant therapy intake after heart valve replacement surgery on patients' knowledge of important parameters of anticoagulant administration. Methods: In this single-center study, 200 patients who underwent surgical implantation of a mechanical prosthesis were divided into 2 groups. The control group received the basic education concerning oral anticoagulants, while the intervention group received a personalized educational program. Results: Personalized education was correlated with a better regulation of therapeutic international normalized ratio (INR) levels and adequate knowledge among patients. Therapeutic levels of INR were achieved in 45% of the patients during the first month, 71% in the third month, and 89% in the sixth month after discharge in the intervention group, compared to 25%, 47%, and 76% in the control group, respectively. Patients' satisfaction with the information was higher in the intervention group than in the control group. The percentage of satisfaction reached 80% for the intervention group versus 37% for the patients of the control group. Conclusion: The implementation of the nurse-led educational programs was associated with improved clinical results and increased adherence to oral anticoagulant treatment.

• Journal of Korean Medical Science
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• v.33 no.49
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• pp.323.1-323.12
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• 2018

Background: Vitamin K antagonist (VKA) to prevent thromboembolism in non-valvular atrial fibrillation (NVAF) patients has limitations such as drug interaction. This study investigated the clinical characteristics of Korean patients treated with VKA for stroke prevention and assessed quality of VKA therapy and treatment satisfaction. Methods: We conducted a multicenter, prospective, non-interventional study. Patients with $CHADS_2{\geq}1$ and treated with VKA (started within the last 3 months) were enrolled from April 2013 to March 2014. Demographic and clinical features including risk factors of stroke and VKA treatment information was collected at baseline. Treatment patterns and international normalized ratio (INR) level were evaluated during follow-up. Time in therapeutic range (TTR) > 60% indicated well-controlled INR. Treatment satisfaction on the VKA use was measured by Treatment Satisfaction Questionnaire for Medication (TSQM) after 3 months of follow-up. Results: A total of 877 patients (age, 67; male, 60%) were enrolled and followed up for one year. More than half of patients (56%) had $CHADS_2{\geq}2$ and 83.6% had $CHA_2DS_2-VASc{\geq}2$. A total of 852 patients had one or more INR measurement during their follow-up period. Among those patients, 25.5% discontinued VKA treatment during follow-up. Of all patients, 626 patients (73%) had poor-controlled INR (TTR < 60%) measure. Patients' treatment satisfaction measured with TSQM was 55.6 in global satisfaction domain. Conclusion: INR was poorly controlled in Korean NVAF patients treated with VKA. VKA users also showed low treatment satisfaction.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.207-212
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• 2010

Protein C deficiency increases the risk of thrombosis due to the lack of anticoagulant factor protein C. Among the numerous congenital protein C deficiencies, homozygous protein C deficiency has an especially low protein C activity level, that it is almost undetectable. It is a rare disease with a probability of 1:250000~500000. The signs and symptoms of homozygous protein C deficiency include purpuric, necrotic dermatosis, ecchymosis, blindness, and thrombosis in central nervous system. A 4-year-old girl was brought to the clinic with a chief complaint of extensive caries. The child was under warfarin medication in order to prevent possible complications during dental treatment. We consulted the pediatric department. Without warfarin intake, serious complications may occur due to thrombosis during dental treatment. Therefore, certain warfarin dosage (INR 3~5) and fresh frozen plasma as a backup for excessive hemorrhage were recommended. This child was a severely disabled child with the loss of vision, and it was difficult to manage her behavior effectively. Thus, dental treatment was carried out under general anesthesia, where bleeding control would be also easier to achieve.This report presents the case of a 4-year-old girl with protein C deficiency, who has received dental treatment for extensive caries under general anesthesia.