Publications by authors named "Yun Shik Choi"

Background: Evidence of the long-term outcomes of abandoned leads (ALs) in patients with cardiac implantable electronic devices (CIEDs) is scarce.

Objective: This study aimed to investigate the long-term outcomes of ALs.

Methods: This retrospective cohort study reviewed a single-center CIED registry of 2962 procedures performed from 1984-2018 and identified 130 patients with AL (AL group).

View Article and Find Full Text PDF

Background: The role of J-waves in the pathogenesis of ventricular fibrillation (VF) occurring in structurally normal hearts is important.

Methods: We evaluated 127 patients who received an implantable cardioverter-defibrillator (ICD) for Brugada syndrome (BS, n = 53), early repolarization syndrome (ERS, n = 24), and patients with unknown or deferred diagnosis (n = 50). Electrocardiography (ECG), clinical characteristics, and ICD data were analyzed.

View Article and Find Full Text PDF

Background And Objectives: Implantable cardioverter defibrillator (ICD) therapy is recommended as the primary tool for prevention of sudden cardiac death (SCD) in symptomatic patients with severe left ventricular dysfunction. There is a paucity of information on whether this recommendation is appropriate for the Korean population with severe heart failure.

Subjects And Methods: The study group consisted of 275 consecutive patients (mean age 65 years, 71% male) who met the ICD implantation criteria for primary prevention (left ventricular ejection fraction ≤30% and New York Heart Association functional class II or III).

View Article and Find Full Text PDF

Introduction: The circadian and seasonal patterns of ventricular tachyarrhythmia (VTA) in patients with early repolarization syndrome (ERS) have not been determined. We compared the timing of VTAs in patients with ERS and Brugada syndrome (BS).

Methods And Results: We enrolled patients with ERS (n = 14) and BS (n = 53) who underwent implantable cardioverter defibrillator (ICD) implantation.

View Article and Find Full Text PDF

Background/aims: Underlying cardiac pathology and atrial fibrillation (AF) affect the molecular remodeling of ion channels in the atria. Changes in the expression of these molecules have not been demonstrated in Korean patients with mitral valvular heart disease. Thus, the purpose of this study was to analyze ion channel expression in patients with chronic AF and mitral valvular heart disease.

View Article and Find Full Text PDF

Transvenous left ventricular (LV) lead implantation is on the increase due to cardiac resynchronization therapy (CRT). However, there has been paucity of data on the prognosis of LV lead. Consecutive 32 patients with LV lead for CRT (n=22) or pacemaker (n=10) were subjected.

View Article and Find Full Text PDF

Background And Objectives: Major epicardial fat pads contain cardiac ganglionated plexi (GP) of the autonomic nervous system. Autonomic denervation may improve the success rate of atrial fibrillation (AF) ablation. This study was designed to elucidate the acute effects of blocking the right atrium-pulmonary vein (RA-PV) and left atrium-inferior vena cava (LA-IVC) fat pads on the electrophysiologic characteristics of the atrium and AF inducibility with a botulinum toxin injection.

View Article and Find Full Text PDF

Background: Catheter ablation targeting of complex fractionated atrial electrograms (CFAEs) is one of the techniques used for atrial fibrillation (AF) ablation. The ablation of sites showing a high-frequency spectral component (HFC) during sinus rhythm, known as AF nests, has been introduced as an adjunct to conventional ablation. Known locations of some AF nests are similar to CFAE sites.

View Article and Find Full Text PDF

Maze operation could alter P wave morphology in electrocardiogram (ECG), which might prevent exact diagnosis of the cardiac rhythm of patients. However, characteristics of P wave in patients with sinus rhythm after the operation have not been elucidated systematically. Consecutive patients who underwent the modified Cox Maze operation from January to December 2007 were enrolled.

View Article and Find Full Text PDF

Background: Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired renal failure and affects mortality and morbidity. There has been no study comparing the efficacy of N-acetylcysteine (NAC) and ascorbic acid that have potential for CIN prevention in patients with renal insufficiency.

Methods: We conducted a prospective randomized controlled trial.

View Article and Find Full Text PDF

Background: Contrast media cause oxidative stress, which has been suggested as one possible mechanism responsible for contrast-induced nephropathy. Statins appear to have pleiotropic effects, including antioxidant properties. We investigated to determine whether simvastatin pretreatment reduces the risk of contrast-induced nephropathy in a high-risk population of patients with renal insufficiency undergoing coronary angiography.

View Article and Find Full Text PDF

Background: Afterload is expected to increase with pneumatic compression of the lower extremities. There are left ventricular (LV) wall stress, which is the most important factor determining myocardial oxygen demand, will also increase, leading to an increase in the sensitivity of dobutamine stress echocardiography (DSE) or a shortened time to a positive response.

Methods And Results: In 40 patients who underwent DSE and were anticipating undergoing coronary angiography (CAG), the imaging was repeated with pneumatic compression (100 mmHg) of the lower extremities (DSEcomp) prior to CAG.

View Article and Find Full Text PDF

Background: Positive longitudinal pre-ejectional velocity (+PEVL) was recently reported to be a reliable index of myocardial recovery early after successful revascularization in myocardial infarction (MI); that is, it recognizes the transmural extent of viable myocardium. The applicability of PEVL in the real-world clinical setting for identifying the transmural extent of viable myocardium in reperfused recent MI was assessed.

Methods And Results: Using tissue Doppler imaging, the resting basal and mid myocardial PEVLs were determined within 3 days after revascularization in 41 consecutive patients with recent MI.

View Article and Find Full Text PDF

Chronic atrial fibrillation (AF) is common in patients with mitral stenosis (MS). Because AF induces electrical and mechanical remodeling of the left atrium, left atrial (LA) compliance is likely to be changed in its presence. This study was performed to investigate the influence of AF on LA compliance in patients with moderate to severe MS.

View Article and Find Full Text PDF

We report a 34-year-old female patient with preexcitation electrocardiogram and recurrent paroxysmal palpitations. Standard 12-lead electrocardiogram showed minimal preexcitation with normal PR interval and normal frontal QRS axis. The electrophysiologic study showed normal AH intervals, short HV intervals, and no change in the degree of preexcitation by rapid atrial pacing.

View Article and Find Full Text PDF

Background: Recent studies suggest that natriuretic peptides are potential biomarkers for myocardial ischemia. However, little is known about the value of NT-proBNP as a predictor of repeat revascularization (RR) at follow-up angiography in patients with normal LV systolic function.

Methods: We collected and analyzed the clinical and angiographic data from 445 consecutive patients (62.

View Article and Find Full Text PDF

Background: The effect of adjunctive heparin for primary angioplasty in patients with ST-elevation myocardial infarction (STEMI) is not well established, so the authors investigated the effect of early heparin administration in the emergency room (ER) on initial patency of the infarct-related artery (IRA) and on the clinical outcome in STEMI patients.

Methods And Results: One hundred and twenty consecutive patients who presented with STEMI less than 12 h from pain onset and who were eligible for primary percutaneous coronary intervention were allocated to an early heparin group (heparin administered in ER) or a late heparin group (heparin administered after angiography). In the early heparin group, unfractionated heparin (60 U/kg bolus IV, then 14 U .

View Article and Find Full Text PDF

Background: Prevention of tachycardia is an important therapeutic strategy in patients with relaxation abnormality.

Methods: Eleven patients with stable relaxation abnormality (group 1) and 8 healthy individuals (group 2) were enrolled. Left ventricular (LV) mean diastolic pressure, LV dimensions, stroke volume (SV), and LV ejection, filling, and isovolumic times between right atrial pacing rates of 80 and 120/min were compared.

View Article and Find Full Text PDF

Background: Speckle tracking echocardiography (STE) has a unique feature of angle independence and, thus, may provide a powerful means of assessing left ventricular (LV) torsion (LVtor). The aims of this study were to assess: (1) the feasibility of 2-dimensional STE in the measurement of LVtor; and (2) the relationship of LVtor with age and conventional echocardiographic parameters.

Methods: We consecutively recruited 160 healthy volunteers.

View Article and Find Full Text PDF

This study was performed to identify echocardiographic parameters related to postoperative clinical outcome in patients who undergo surgery for severe tricuspid regurgitation after mitral valve surgery. Eighteen patients (2 men, 16 women; mean age 58 years) were prospectively enrolled. Echocardiographic examinations were performed before and 15 +/- 7 months after surgery.

View Article and Find Full Text PDF

Beta-catenin is a transcriptional regulator of several genes involved in survival and proliferation. Although previous studies suggest that beta-catenin may be involved in the process of preconditioning and healing after myocardial infarction (MI), little is known regarding the role of beta-catenin in cardiomyocytes and cardiac fibroblasts. We investigated the role of beta-catenin in cardiomyocytes and cardiac fibroblasts and whether beta-catenin overexpression could reduce MI size.

View Article and Find Full Text PDF

We performed a prospective study of patients with chronic right ventricular (RV) dilation to determine the factors associated with the degree of functional tricuspid regurgitation (FTR). We prospectively enrolled 64 patients with chronic RV dilation and measured right atrial (RA) area, RV area and its fractional area change (RVFAC), tricuspid annular diameter and contraction, tricuspid valve (TV) tethering area, and systolic pulmonary artery pressure. We also measured the RV eccentricity index and the RV sphericity index for simple presentation of RV geometry.

View Article and Find Full Text PDF

Background: Previous studies demonstrated impaired coronary vasodilatory response (VR) to nitroglycerin (NG) in patients with coronary atherosclerosis. We hypothesized that the effect of the NG on the coronary blood flow (CBF) is negligible compared with its effect on the epicardial coronary artery dilatation and, therefore, that CBF velocity reduction after NG can reflect the magnitude of epicardial coronary artery dilatation.

Methods: Quantitative coronary angiography was performed at the left anterior descending coronary artery (LAD) before and after intracoronary NG (200 mug) infusion in 18 patients with normal-looking coronary angiogram.

View Article and Find Full Text PDF