BACKGROUND AND OBJECTIVES: Heart rate variability has been known to be a prognostic factor of heart disease. However, determinants of heart rate variability in general korean population without clinical heart disease have not been studied. Objectives of this study were to measure heart rate variability in general population and to investigate clinical determinants of heart rate variability. METHODS:Heart rate variability measures were obtained by LRR-03TM and MemCalcTM software (GMS, Tokyo, Japan) from public officials in a district of Seoul and their families(n=69). Predictors of heart rate variability included age, gender, heart rate, smoking status, systolic blood pressure, diastolic blood pressure, serum total cholesterol, HDL-cholesterol. Univariate analysis and analysis of variance of low frequency power(0.04-0.15 Hz), high frequency power(0.15-0.30 Hz), and total power spectrum in relation to explanatory variables were done. In order to select determinants of heart rate variability, multiple linear regression model of each heart rate variability measure was created and stepwise selection method was applied. RESULTS: Analysis of variance showed that older age, higher heart rate, body mass index > or =27, systolic blood pressure > or =140 mmHg, diastolic blood pressure > or =90 mmHg, and serum total cholesterol > or =240 mg/dl were negatively associated with one or more heart rate variability measures. Serum HDL-cholesterol > or =35 mg/dl was positively associated with low and high frequency power. Multiple linear regression analyses showed that age and heart rate were the major determinants, gender and cardiovascular risk factors such as diastolic blood pressure, HDL-cholesterol, and smoking contributed to one or more heart rate variability measures. CONCLUSIONS: Age, heart rate, gender, and cardiovascular risk factors must be considered when evaluating heart rate variability.
Blood Pressure ; Body Mass Index ; Cholesterol ; Heart Diseases ; Heart Rate* ; Heart* ; Linear Models ; Risk Factors ; Seoul ; Smoke ; Smoking

BACKGROUND: Left ventricular (LV) remodeling manifests as an increase in LV end-diastolic and end-systolic volumes, an increase in myocardial mass, and a change in chamber geometry to a more spherical shape, and has been considered to be a consequence of heart failure, myocardial infarction or mitral regurgitation. However, less is known about change of LV geometry, especially LV sphericity, in asymptomatic population according to aging. METHODS:We investigated 261 asymptomatic subjects who volunteered for health screening and underwent transthoracic echocardiography. Those with poor echo image, significant coronary artery disease, LV dysfunction, hypertension, and diabetes mellitus were excluded. LV sphericity index is defined as the ratio of the long-axis length divided by LV short-axis length, both during systole and diastole. LV mass was calculated from septal and posterior wall thickness and LV internal dimension at end-diastole and then divided by body surface area to calculate LV mass index RESULTS: The mean age of subjects was 49.6+/-6.7 years and the percentage of male was 81%. LV sphericity index at diastole showed significant correlation with age (r=-0.17, p value<0.01), but LV sphericity index at systole did not. Both indices did not showed significant association with aerobic fitness, blood pressure, glucose, insulin resistance and LV function. LV mass index showed significant correlation with age (r=0.14, p value<0.05). CONCLUSION: Among the parameters of LV geometry, sphericity index showed decrease with aging in healthy population, meaning LV becoming more spherical with aging. Longitudinal follow-up study is needed to determine its usefulness as a predictor of future LV dysfunction in asymptomatic population.
Aging ; Blood Pressure ; Body Surface Area ; Coronary Artery Disease ; Diabetes Mellitus ; Diastole ; Echocardiography ; Glucose ; Heart Failure ; Humans ; Hypertension ; Insulin Resistance ; Male ; Mass Screening ; Mitral Valve Insufficiency ; Myocardial Infarction ; Systole

Heart rate (HR) recovery after exercise is a function of vagal reactivation, and its impairment is a predictor of overall mortality and adverse cardiovascular events. While metabolic syndrome is associated with sympathetic overactivity, little is known about the relationship between metabolic syndrome and HR recovery. A symptom-limited exercise stress test in healthy subjects (n=1, 434) was used to evaluate HR recovery. Metabolic syndrome was defined according to the National Cholesterol Education Program's Adult Treatment Panel III (NCEP ATP-III) criteria. Seventeen percent of subjects had > or =3 criteria for metabolic syndrome. HR recovery was lower in men than women and in smokers than nonsmokers. The subject with metabolic syndrome (vs. without) showed lower HR recovery (10.3+/-11.6 vs. 13.6+/-9.7 per minute) and higher resting HR (64.3+/-10.3 vs. 61.6+/-9.1 per minute). HR recovery correlated inversely to age (r=-0.25, p<0.0001), but not to resting HR or maximal oxygen uptake. Delayed HR recovery was associated with metabolic syndrome after an adjustment for age, sex, resting HR and smoking (p<0.01). Metabolic syn-drome is associated with impaired vagal reactivation. Adverse cardiovascular out-comes associated with metabolic syndrome may be mediated by the failure of vagal reactivation in addition to sympathetic overactivity.
Walking/physiology ; Smoking ; Sex Factors ; Oxygen Consumption/physiology ; Middle Aged ; Metabolic Syndrome X/blood/*physiopathology ; Male ; Humans ; Heart Rate/*physiology ; Female ; Fasting/blood ; Exercise/*physiology ; Cholesterol, HDL/blood ; Body Mass Index ; Blood Pressure/physiology ; Blood Glucose/metabolism ; Analysis of Variance ; Age Factors ; Adult

Cardiovascular diseases including ischemic heart disease have been emerging as one of the most important public health problems in Korea. Although secondary prevention and rehabilitation are essential components in the management of patients with ischemic heart disease, its program has not been provided to all the patients. There are several barriers, such as availability and accessibility, low awareness of both patients and physicians in implementing cardiac rehabilitation program. Home-based and community-based programs under the direction of medical supervision are needed to further widen its availability and accessibility, as well as hospital-based programs. Cardiac rehabilitation programs emphasize risk factor control and life style change, besides exercise training. Health education, diet, counseling, psychosocial support, and exercise are all important in restoring the patient's quality of life. For this purpose, cardiac rehabilitation should be well integrated with preventive cardiology, and a multidisciplinary approach is mandatory. Since Korean society is very rapidly aging, a big impact on future trend of ischemic heart disease, preventive cardiology and cardiac rehabilitation will play a very important role to overcome the approaching wave of cardiovascular epidemic.
Aging ; Cardiology ; Cardiovascular Diseases ; Coronary Artery Disease* ; Coronary Vessels* ; Counseling ; Diet ; Health Education ; Humans ; Korea ; Life Style ; Myocardial Ischemia ; Organization and Administration ; Public Health ; Quality of Life ; Rehabilitation* ; Risk Factors ; Secondary Prevention

Cardiovascular diseases including ischemic heart disease have been emerging as one of the most important public health problems in Korea. Although secondary prevention and rehabilitation are essential components in the management of patients with ischemic heart disease, its program has not been provided to all the patients. There are several barriers, such as availability and accessibility, low awareness of both patients and physicians in implementing cardiac rehabilitation program. Home-based and community-based programs under the direction of medical supervision are needed to further widen its availability and accessibility, as well as hospital-based programs. Cardiac rehabilitation programs emphasize risk factor control and life style change, besides exercise training. Health education, diet, counseling, psychosocial support, and exercise are all important in restoring the patient's quality of life. For this purpose, cardiac rehabilitation should be well integrated with preventive cardiology, and a multidisciplinary approach is mandatory. Since Korean society is very rapidly aging, a big impact on future trend of ischemic heart disease, preventive cardiology and cardiac rehabilitation will play a very important role to overcome the approaching wave of cardiovascular epidemic.
Aging ; Cardiology ; Cardiovascular Diseases ; Coronary Artery Disease* ; Coronary Vessels* ; Counseling ; Diet ; Health Education ; Humans ; Korea ; Life Style ; Myocardial Ischemia ; Organization and Administration ; Public Health ; Quality of Life ; Rehabilitation* ; Risk Factors ; Secondary Prevention

The purpose of this study was to examine professors’ and students’ perceptions of curriculum that fosters character in medical school. ‘Character’ can be defined as a desirable personality and the ability to be a good person. A total of 264 subjects (professors=131, students=133) participated in the study. Survey questions were divided into the three parts (education needs, factors of character, and curriculum management strategy). Data were analyzed by using t-test and one-way analysis of variance. Both professors and students recognized the need for character education. Professors were more aware of the need for education than students (t=4.35, p<0.01), and clinical professors were more aware of the need for education than basic medical science professors (t=3.48, p<0.01). Premedical students were more aware of the need for character-centered education than medical students in the later stages of their education (t=3.41, p<0.01). Professors and students commonly referred to ‘consideration and communication’ as the most important factor in building character. Professors considered ‘self-regulation’ more important than the students recognized, while students perceived ‘wisdom’ as more important than the professors did. There was a difference in preference for curriculum development (creating new subjects vs. revising existing subjects) between the two groups. However, both groups agreed on the teaching and evaluation methods. In conclusion, both groups acknowledged the need for character education. However, there were differences in perception on the major factors of character and preference for curriculum development. The results of this study may assist in designing character education in medical education.

PURPOSE: Blood pressure variability (BPV) is emerging as an important cardiovascular prognostic factor in addition to average blood pressure level. While there have been some suggestions for the determinants of the blood pressure variability, little is known about the relationship between the blood pressure variability and health-related quality of life (QOL). MATERIALS AND METHODS: Fifty-six men and women with mild hypertension were enrolled from local health centers in Republic of Korea, from April to October 2009. They self-monitored their blood pressure twice daily for 8 weeks. Pharmacological treatment was not changed during the period. Standard deviation and coefficient of variation of blood pressure measurements were calculated as indices of BPV. Measurements of QOL were done at initial and at 8-week follow-up visits. RESULTS: Study subjects had gender ratio of 39:41 (male:female) and the mean age was 64+/-10 years. The mean home blood pressure's at week 4 and 8 did not differ from baseline. Total score of QOL at follow-up visit and change of QOL among two measurements were negatively correlated to BPV indices, i.e., higher QOL was associated with lower BPV. This finding persisted after adjustment for age, gender and the number of antihypertensive agents. Among dimensions of QOL, physical, mental and hypertension-related dimensions were associated particularly with BPV. CONCLUSION: QOL may be a significant determinant of BPV. Improvement of QOL may lead to favorable changes in BPV.
Antihypertensive Agents ; Blood Pressure* ; Female ; Follow-Up Studies ; Humans ; Hypertension ; Male ; Methods ; Quality of Life* ; Republic of Korea

BACKGROUND AND OBJECTIVES: There has been a need for functional status measurement tool with better validity than the existing tools such as New York Heart Association Functional Class. Duke Activity Status Index (DASI) is a representative example of a tool that was developed to enhance the validity of measurement by asking the patients about the ability to perform specific activities and scoring the response. Because such a tool must be culture-sensitive, it is desirable to use 'Koreanized' version of the tool. No Koreanized version of the functional status measurement tool has been developed yet. The objective of this study is to develop a Korean version of DASI. MATERIALS AND METHOD: In the developmental phase, a pilot questionnaire asking the ability to perform specific activity was made with reference to existing tools, such as Specific Activity Scale and DASI. Substitution, correction and addition of items were done through the pilot study. Ninety-nine patients was asked to fill developmental version of questionnaire, then underwent treadmill exercise test. Weight for each items were assigned to optimize the correlation between the calculated index (KASI) and total treadmill exercise time. Criteria for categorical functional classification were determined to maximize the agreement between KASI-estimated functional class (KASIFC) and functional class estimated by exercise time. In the validation phase, final version of questionnaire was tested in independent group of 159 patients. The questionnaire was self-administered. Canadian Cardiovascular Society Functional Class (CCSFC) was estimated by the physician who is in charge of treadmill exercise test. RESULTS: In the validation phase, Spearman correlation coefficient between KASI and treadmill exercise time was 0.62(p=.0001) and between CCSFC and exercise time -0.48(p=.0001). KASIFC agreed with functional class estimated by exercise time in 77% of cases, disagreed by 1 class in 20% and by 2 classes in 1%. KASIFC agreed with functional class estimated by exercise time in 77% of cases, disagreed by 1 class in 20% and by 2 classes in 1%. These two methods did not differ significantly in categorical classification. CONCLUSION: KASI is more accurate or at least as accurate as the existing tool in estimation of functional status. The characteristics such as self-administration, availability of outcome as a continuous variable are expected to make it a convenient, efficacious and useful tool in various clinical researches.
Classification ; Exercise Test ; Heart ; Humans ; Pilot Projects ; Surveys and Questionnaires

BACKGROUND AND OBJECTIVES: There has been a need for functional status measurement tool with better validity than the existing tools such as New York Heart Association Functional Class. Duke Activity Status Index (DASI) is a representative example of a tool that was developed to enhance the validity of measurement by asking the patients about the ability to perform specific activities and scoring the response. Because such a tool must be culture-sensitive, it is desirable to use 'Koreanized' version of the tool. No Koreanized version of the functional status measurement tool has been developed yet. The objective of this study is to develop a Korean version of DASI. MATERIALS AND METHOD: In the developmental phase, a pilot questionnaire asking the ability to perform specific activity was made with reference to existing tools, such as Specific Activity Scale and DASI. Substitution, correction and addition of items were done through the pilot study. Ninety-nine patients was asked to fill developmental version of questionnaire, then underwent treadmill exercise test. Weight for each items were assigned to optimize the correlation between the calculated index (KASI) and total treadmill exercise time. Criteria for categorical functional classification were determined to maximize the agreement between KASI-estimated functional class (KASIFC) and functional class estimated by exercise time. In the validation phase, final version of questionnaire was tested in independent group of 159 patients. The questionnaire was self-administered. Canadian Cardiovascular Society Functional Class (CCSFC) was estimated by the physician who is in charge of treadmill exercise test. RESULTS: In the validation phase, Spearman correlation coefficient between KASI and treadmill exercise time was 0.62(p=.0001) and between CCSFC and exercise time -0.48(p=.0001). KASIFC agreed with functional class estimated by exercise time in 77% of cases, disagreed by 1 class in 20% and by 2 classes in 1%. KASIFC agreed with functional class estimated by exercise time in 77% of cases, disagreed by 1 class in 20% and by 2 classes in 1%. These two methods did not differ significantly in categorical classification. CONCLUSION: KASI is more accurate or at least as accurate as the existing tool in estimation of functional status. The characteristics such as self-administration, availability of outcome as a continuous variable are expected to make it a convenient, efficacious and useful tool in various clinical researches.
Classification ; Exercise Test ; Heart ; Humans ; Pilot Projects ; Surveys and Questionnaires

BACKGROUND AND OBJECTIVES: Percutaneous coronary intervention (PCI) is an indispensable treatment modality in coronary artery disease. However, there is still inadequacy of comprehensive knowledge on the Korean status and trend of this important procedure using nation-wide and representative data. METHODS: National Health Insurance Service-National Sample Cohort is a database containing demographic, health insurance reimbursement for patient management and health screening data of about one million Koreans for 12 years (2002–2013). Annual procedure rate for PCI was estimated by bootstrapping as per 100,000 person-years. RESULTS: Among the whole cohort, total 12,186 PCI's were done during the study period. Mean age of subjects who underwent PCI was 57.6±11.2 years and male:female proportion was 68%:32%. Death from all cause occurred in 1,843 (15.1%), death from ischemic heart diseases in 662 (5.4%), death from all cardiovascular cause in 872 (7.2%) during the follow-up. The proportion of the primary PCI for acute myocardial infarction was estimated to be 24.0%. Estimated annual rate of PCI increased from median 29.1 (95% confidence interval [CI], 26.6–32.1) in 2002 to 107.7 (95% CI, 103.0–113.8) per 100,000 person-years in 2013. In this cohort, PCI was performed in total 180 hospitals, which annually increased from 59 in 2002 to 153 in 2013. CONCLUSIONS: PCI had increased in volume from 2002 to 2013. This descriptive data may be considered in policy making and planning further direction of management of coronary artery disease in Korea.
Cohort Studies ; Coronary Artery Disease ; Follow-Up Studies ; Humans ; Insurance, Health, Reimbursement ; Korea ; Mass Screening ; Myocardial Infarction ; Myocardial Ischemia ; National Health Programs ; Percutaneous Coronary Intervention ; Policy Making