• The Journal of the Acoustical Society of Korea
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• v.26 no.4
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• pp.144-152
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• 2007

Conventional research works on the classification of the heart sound signal have been done mainly with the artificial neural networks. But the analysis results on the statistical characteristic of the heart sound signal have shown that the HMM is suitable for modeling the heart sound signal. In this paper, we model the various heart sound signals representing different heart diseases with the HMM and find that the classification rate is much affected by the clustering of the heart sound signal. Also, the heart sound signal acquired in real environments is a continuous signal without any specified starting and ending points of time. Hence, for the classification based on the HMM, the continuous cyclic heart sound signal needs to be manually segmented to obtain isolated cycles of the signal. As the manual segmentation will incur the errors in the segmentation and will not be adequate for real time processing, we propose a variant of the ergodic HMM which does not need segmentation procedures. Simulation results show that the proposed method successfully classifies continuous heart sounds with high accuracy.

• Applied Microscopy
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• v.33 no.4
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• pp.325-333
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• 2003

Fine structural characteristics of the heart tube and its cardiac muscle cells in spider, Araneus ventricosus are investigated by both of scanning and transmission electron microscopes. The heart tube of the spider is extended mid-dorsally along the anterior part of the abdomen, and is consisted of the thin outer layer of connective tissue (epicardium) and the thick muscle layer (myocardium). The myocardium in the spider has a typical fanlike spiral structure toward anterior part put across between the muscle fibers. Therefore, it did not give rise to the intima, and muscle cells are in direct contact to the hemolymph. The heart tube appeared to be three pairs of ostia and numerous hemocytes accumulated at the inner surface of the myocardial layer. Among several kinds of the hemocytes, the oenocytoids are the most predominant hemocytes accumulated along the myocardial folds which stretched toward heart lumen. The heart muscle cells are cross striated, branched, and multinucleated. They contain a lot of mitochondria, which provide for the continuous energy demands of the heart. Thread-like ganglion on the dorsal side of the heart tube gives off axons that innervate the heart muscle cells.

• BMB Reports
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• v.52 no.8
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• pp.526-531
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• 2019

The vertebrate body plan is accomplished by left-right asymmetric organ development and the heart is a representative asymmetric internal organ which jogs to the left-side. Kupffer's vesicle (KV) is a spherical left-right organizer during zebrafish embryogenesis and is derived from a cluster of dorsal forerunner cells (DFCs). Cadherin1 is required for collective migration of a DFC cluster and failure of DFC collective migration by Cadherin1 decrement causes KV malformation which results in defective heart laterality. Recently, loss of function mutation of A-kinase anchoring protein 12 (AKAP12) is reported as a high-risk gene in congenital heart disease patients. In this study, we demonstrated the role of $akap12{\beta}$ in asymmetric heart development. The $akap12{\beta}$, one of the akap12 isoforms, was expressed in DFCs which give rise to KV and $akap12{\beta}$-deficient zebrafish embryos showed defective heart laterality due to the fragmentation of DFC clusters which resulted in KV malformation. DFC-specific loss of $akap12{\beta}$ also led to defective heart laterality as a consequence of the failure of collective migration by cadherin1 reduction. Exogenous $akap12{\beta}$ mRNA not only restored the defective heart laterality but also increased cadherin1 expression in $akap12{\beta}$ morphant zebrafish embryos. Taken together, these findings provide the first experimental evidence that $akap12{\beta}$ regulates heart laterality via cadherin1.

• Journal of Korean Critical Care Nursing
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• v.6 no.2
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• pp.51-64
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• 2013

Purpose: This study was to analyze adherence to self-care behaviors and identify factors affecting the adherence behaviors among inpatients with heart failure. Methods: A total 94 hospitalized inpatients from three hospitals participated in a survey. Data were collected using structured self-reported questionnaire from November 28, 2011 to March 31, 2013 and analyzed using frequency, t-test, ANOVA, Pearson's correlation coefficients and stepwise multiple regression. Results: The score of adherence to self-care behaviors among inpatients with heart failure was $26.02({\pm}8.84)$. Factors related to the adherence to self-care behaviors were living with spouse (t=-2.47, p=.019), functional state (t=2.18, p=.034), heart failure knowledge (r=-.49, p<.001), social support (r=-.35, p<.001), self-control (r=-.25, p=.016), and self-care confidence (r=-.24, p=.019). The factors affecting adherence to self-care behaviors were heart failure knowledge, self-care confidence, and social support. These factors explained 32% of the variance in adherence to self-care behaviors. Conclusion: The adherence to self-care behaviors with heart failure can be improved if heart failure knowledge, self-care confidence, and social support are improved. Therefore, developing a nursing intervention program for patient with heart failure that is considered these factors leads to improve quality of life and prevent readmission.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.22-28
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• 2013

It is important to begin left ventricular assist device (LVAD) treatment at appropriate time for heart failure patients who expect cardiac recovery after the therapy. In order to predict the optimal timing of LVAD implantation, we predicted pumping efficacy of LVAD according to the severity of heart failure theoretically. We used LVAD-implanted cardiovascular system model which consist of 8 Windkessel compartments for the simulation study. The time-varying compliance theory was used to simulate ventricular pumping function in the model. The ventricular systolic dysfunction was implemented by increasing the end-systolic ventricular compliance. Using the mathematical model, we predicted cardiac responses such as left ventricular peak pressure, cardiac output, ejection fraction, and stroke work according to the severity of ventricular systolic dysfunction under the treatments of continuous and pulsatile LVAD. Left ventricular peak pressure, which indicates the ventricular loading condition, decreased maximally at the 1st level heart-failure under pulsatile LVAD therapy and 2nd level heart-failure under continuous LVAD therapy. We conclude that optimal timing for pulsatile LVAD treatment is 1st level heart-failure and for continuous LVAD treatment is 2nd level heart-failure when considering LVAD treatment as "bridge to recovery".

• Child Health Nursing Research
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• v.25 no.3
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• pp.262-272
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• 2019

Purpose: We aimed to identify factors influencing physical activity in adolescents with complex congenital heart disease. Methods: We recruited 92 adolescents with complex congenital heart disease from a tertiary medical center in Seoul, measured their levels of physical activity, and identified factors that influenced their physical activity levels using the Global Physical Activity Questionnaire, the New York Heart Association classification, congenital heart disease complexity, the Self-Efficacy Scale, and the Parental Bonding Instrument scale. Stepwise multiple linear regression was used to determine factors influencing physical activity. Results: Total physical activity was higher in males than in females (t=4.46, p<.001). Adolescents who participated in school physical education classes engaged in more physical activity than those who did not (t=6.77, p<.001). Higher self-efficacy (${\beta}=.41$, p<.001), male gender (${\beta}=.37$, p<.001) and participation in school physical education classes (${\beta}=.19$, p=.042) were associated with a higher likelihood of engagement in physical activity. Conclusion: It is necessary to develop nursing interventions that enhance self-efficacy in order to promote physical activity in adolescents with complex congenital heart disease. Physical activity should also be promoted in an individualized manner, taking into account gender, disease severity, and parental attitude.

• BMB Reports
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• v.43 no.6
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• pp.432-437
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• 2010

LBH is a transcription factor as a candidate gene for CHD associated with partial trisomy 2p syndrome. To identify potential LBH-interacting partners, a yeast two-hybrid screen using LBH as a bait was performed with a human heart cDNA library. One of the clones identified encodes ${\alpha}B$-crystallin. Co-immunoprecipitation and GST pull-down assays showed that LBH interacts with ${\alpha}B$-crystallin, which is further confirmed by mammalian two-hybrid assays. Co-localization analysis showed that in COS-7 cells, ${\alpha}B$-crystallin that is cytoplasmic alone, accumulates partialy in the nucleus when co-transfected with LBH. Transient transfection assays indicated that overexpression of LBH or ${\alpha}B$-crystallin reduced the transcriptional activities of p53 and p21, respectively, Overexpression of both ${\alpha}B$-crystallin and LBH together resulted in a stronger repression of the transcriptional activities of p21 and p53. These results showed that the interaction of LBH and ${\alpha}B$-crystallin may inhibit synergistically the transcriptional regulation of p53 and p21.

• Korean Circulation Journal
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• v.53 no.7
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• pp.425-451
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• 2023

Most patients with heart failure (HF) have multiple comorbidities, which impact their quality of life, aggravate HF, and increase mortality. Cardiovascular comorbidities include systemic and pulmonary hypertension, ischemic and valvular heart diseases, and atrial fibrillation. Non-cardiovascular comorbidities include diabetes mellitus (DM), chronic kidney and pulmonary diseases, iron deficiency and anemia, and sleep apnea. In patients with HF with hypertension and left ventricular hypertrophy, renin-angiotensin system inhibitors combined with calcium channel blockers and/or diuretics is an effective treatment regimen. Measurement of pulmonary vascular resistance via right heart catheterization is recommended for patients with HF considered suitable for implantation of mechanical circulatory support devices or as heart transplantation candidates. Coronary angiography remains the gold standard for the diagnosis and reperfusion in patients with HF and angina pectoris refractory to antianginal medications. In patients with HF and atrial fibrillation, longterm anticoagulants are recommended according to the CHA₂DS₂-VASc scores. Valvular heart diseases should be treated medically and/or surgically. In patients with HF and DM, metformin is relatively safer; thiazolidinediones cause fluid retention and should be avoided in patients with HF and dyspnea. In renal insufficiency, both volume status and cardiac performance are important for therapy guidance. In patients with HF and pulmonary disease, beta-blockers are underused, which may be related to increased mortality. In patients with HF and anemia, iron supplementation can help improve symptoms. In obstructive sleep apnea, continuous positive airway pressure therapy helps avoid severe nocturnal hypoxia. Appropriate management of comorbidities is important for improving clinical outcomes in patients with HF.

• Current Optics and Photonics
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• v.3 no.1
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• pp.1-7
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• 2019

Optical stimulation provides a promising alternative to electrical stimulation to selectively modulate tissue. However, developing noninvasive techniques to directly stimulate excitable tissue without introducing genetic modifications and minimizing cellular stress remains an ongoing challenge. Infrared (IR) light has been used to achieve optical pacing for electrophysiological studies in embryonic quail and mammalian hearts. Here, we demonstrate optical stimulation and pacing of the embryonic chicken heart using a pulsed infrared thulium laser with a wavelength of 1927 nm. By recording stereomicroscope outputs and quantifying heart rates and movements through video processing, we found that heart rate increases instantly following irradiation with a large spot size and high radiant exposure. Targeting the atrium using a smaller spot size and lower radiant exposure achieved pacing, as the heart rate synchronized with the laser to 2 Hz. This study demonstrates the viability of using the 1927 nm thulium laser for cardiac stimulation and optical pacing, expanding the optical parameters and IR lasers that can be used to modulate cardiac dynamics.

• Korean Circulation Journal
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• v.53 no.9
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• pp.635-644
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• 2023

Background and Objectives: The History, Electrocardiography, Age, Risk factors, and Troponin (HEART) pathway was developed to identify patients at low risk of a major adverse cardiac event (MACE) among patients presenting with chest pain to the emergency department. Methods: We modified the HEART pathway by replacing the Korean cut-off of 25 kg/m² with the conventional threshold of 30 kg/m² in the definition of obesity among risk factors. The primary outcome was a MACE within 30 days, which included acute myocardial infarction, primary coronary intervention, coronary artery bypass grafting, and all-cause death. Results: Of the 1,304 patients prospectively enrolled, MACE occurred in 320 (24.5%). The modified HEART pathway identified 37.3% of patients as low-risk compared with 38.3% using the HEART pathway. Of the 500 patients classified as low-risk with HEART pathway, 8 (1.6%) experienced MACE, and of the 486 low-risk patients with modified HEART pathway, 4 (0.8%) experienced MACE. The modified HEART pathway had a sensitivity of 98.8%, a negative predictive value (NPV) of 99.2%, a specificity of 49.0%, and a positive predictive value (PPV) of 38.6%, compared with the original HEART pathway, with a sensitivity of 97.5%, a NPV of 98.4%, a specificity of 50.0%, and a PPV of 38.8%. Conclusions: When applied to Korean population, modified HEART pathway could identify patients safe for early discharge more accurately by using body mass index cut-off levels suggested for Koreans.