Yun Shik Choi

Effect of red ginseng on blood pressure in patients with essential hypertension and white coat hypertension.

The objective of this study is to evaluate the changes of diurnal blood pressure pattern after 8 weeks of red ginseng medication (4.5 g/day) by 24 hour ambulatory blood pressure monitoring. In 26 subjects with essential hypertension, 24 hour mean systolic blood pressure decreased significantly (p = 0.03) while diastolic blood pressure only showed a tendency of decline (p = 0.17). The decrease in pressures were observed at daytime (8 A.M.-6 P.M.) and dawn (5 A.M.-7 A.M.). In 8 subjects with white coat hypertension, no significant blood pressure change was observed. We suggest that red ginseng might be useful as a relatively safe medication adjuvant to current antihypertensive medications.

Takayasu arteritis in Korea: Clinical and angiographic features

SummaryClinical and angiographic features of Takayasu arteritis were investigated in 129 Korean patients. This disease affects females more frequently than males, in a ratio of 6.6 to 1. Of the total number of patients, 51 were in the third decade, 27 in the fourth decade, and 23 in the second decade. Common clinical symptoms were headache (60%), exertional dyspnea (42%), dizziness (36%), and malaise or weakness (34%). Takayasu arteritis affected the abdominal aorta (46%) and descending thoracic aorta (37%) more frequently than the ascending aorta (1%) and aortic arch (2%) According to Uenos classification based on aortographic findings, the 129 patients were divided into type I (37), type II (25), and type III (67). Among the 48 patients who had coronary angiography, 11 (23%) showed coronary arterial involvement. Because the clinical features are determined by the extent and severity of the specific artery involved in the occlusive phase of the disease, total aortography including coronary angiography is very important in the initial evaluation of Takayasu arteritis.

Improvement of Endothelial function by Amlodipine and Vitamin C in Essential Hypertension

Background The effects of antihypertensive agents on endothelial function have not been fully evaluated in human hypertension and data on the forearm circulation of humans are controversial. The aim of this study was (1) to evaluate the endothelial function in hypertensive patients (2) to investigate whether vitamin C administration has any benefit on the endothelial function and (3) to determine whether treatment with calcium antagonist improves endothelial dysfunction in hypertensive patients. Methods The endothelial function was estimated using venous occlusion plethysmography (VOP) in 8 hypertensive patients and 8 healthy volunteers. The patients in the hypertension group were treated with amlodipine, then examined again. The change of forearm blood flow (FBF) was measured with acetylcholine infusion through brachial artery and also with intra-arterial vitamin C. Results Forearm blood flow response to acetylcholine was significantly enhanced with intra-arterial infusion of vitamin C in hypertensive group before antihypertensive treatment. Co-infusion of L-NMMA, an inhibitor of nitric oxide synthase, blunted forearm blood flow response to acetylcholine. After treatment with amlodipine for 2 months in hypertensive group, endothelium-dependent vasorelaxation to acetylcholine was significantly improved compared to pretreatment, and vitamin C did not affect the improved endothelial function by amlodipine treatment. Conclusion Vitamin C (acutely) and amlodipine (chronically) improved endothelial function in hypertensive patients. These results suggest that increased oxidative stress, at least in part, may be involved in the decreased endothelial function in hypertension.

Cough Syncope Caused by Sinus Arrest in a Patient with Sick Sinus Syndrome

Cough syncope is a syndrome in which dizziness or syncope occurs after prolonged bouts of cough. This paper presents a case of 63‐year‐old man with recurrent dizziness and syncope. The 24‐hour ambulatory electrocardiogram and intracardiac electrogram showed sinus node dysfunction with sinas arrest, both spontaneous and inducible by voluntary cough. Sinus arrest was sometimes associated with dizziness. A permanent WI pacemaker was implanted and no further cough syncope has occurred. We suggest that sinus arrest may play a role as a mechanism of cough syncope in a patient with sick sinus syndrome.

Remodeling of Ion Channel Expression in Patients with Chronic Atrial Fibrillation and Mitral Valvular Heart Disease

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. Methods A total of 17 patients (eight males and nine females; mean age, 57 ± 14 years [range, 19 to 77]) undergoing open-heart surgery were included in the study. Twelve patients (seven with coronary artery disease and five with aortic valvular disease) had sinus rhythm, and five patients (all with mitral valvular disease) had chronic, permanent AF. A piece of right atrial appendage tissue (0.5 g) was obtained during surgery. RT-PCR was used to evaluate the expression of L-type Ca2+ channels, ryanodine receptor (RyR2), sarcoplasmic reticular Ca2+-ATPase (SERCA2), gene encoding the rapid component of the delayed rectifier Ikr (HERG), gene encoding calcium-independent transient outward current Ito1 (Kv4.3), gene encoding the ultrarapid component of the delayed rectifier Iku (Kv1.5), K+ channel-interacting protein 2 (KChIP2), hyperpolarization-activated cation channel 2 associated with the pacemaker current If (HCN2), and gene encoding Na+ channel (SCN5A). Results Reduced L-type Ca2+ channel, RyR2, SERCA2, Kv1.5, and KChIP2 expression and borderline increased HCN2 expression were observed in the patients with AF and mitral valvular heart disease. Left atrial diameter was negatively correlated with RyR2 and KChIP2 expression. Fractional area shortening of the left atrium was positively correlated with RyR2 and KChIP2 expression. Conclusions Alterations in ion channel expression and the anatomical substrate may favor the initiation and maintenance of AF in patients with mitral valvular heart disease.

Temperature-guided radiofrequency cathether ablation of slow pathway in atrioventricular nodal reentrant tachycardia☆

During the last several years, catheter ablation techniques with radiofrequency current have developed dramatically and have become the method of choice for curative therapy of atrioventricular (AV) nodal reentrant tachycardia. Initial reports have achieved AV nodal fast-pathway ablation with excellent results, but AV nodal slow-pathway ablation is currently the alternative to fast-pathway ablation because of an excellent success rate of 90 % to 100 % and the lower risk of AV block. 13 The ablative effect of radiofrequency energy is based on direct electric (resistive) heating and passive (conductive) heating of the tissue adjacent to the ablating electrode. 4 Assuming that only temperature is the basis for the ablative effects of radiofrequency energy, the temperature of the electrode-tissue interface is more reliable and a better predictor of radiofrequency lesion volume than other variables such as power output, duration of energy delivery, contact pressure of ablation electrode, size of electrode tip, and cavity blood flow. 57 Very few published studies were performed carefully to investigate the effects of temperature-guided radiofrequency catheter ablation on the treatment of AV nodal reentrant tachycardia. This investigation was performed to evaluate the efficacy and safety of temperature-guided radiofrequency catheter ablation of slow pathway for the treatment of AV nodal reentrant tachycardia. The study population consisted of 34 consecutive patients with symptomatic AV nodal reentrant tachycardia for 12 _+ 10 years (range 1 to 40 years). The 10 men and 24 women had a mean age of 44 _+ 16 years (range 14 to 72 years). Structural heart disease was present in four patients: mitral valve prolapse in 2, mitral stenosis in 1, and aortic valve regurgitation in 1. Electrophysiologic study and catheter ablation were performed with quadripolar

Steady state photoconductivity of poly(2-styryl-1, 4- phenylene vinylene) (PSPV)

Abstract The steady state photoconductivities of poly(2-styryl-1,4-phenylene vinylene) (PSPV) and its oxidized form poly(2-methoxy-5-styryl 1, 4-phenyIene vinylene) (PMSPV) are studied. PSPV contains styryl radical in PPV backbone chain. The spectral response of the photocurrent of PSPV shows a peak at 2.7 eV with no additional peak structure near 2.4 eV. PMSPV made by the substitution of methoxy radical to PSPV shows somewhat unusual feature. The spectral response of PMSPV does not show any peak near the absorption edge and the magnitude of the photocurrent is decreased compared to that of the PSPV. The results are discussed in terms of the different interchain distances of the two polymers as well as the existence of a conjugated double bond in the styryl radical in these PPV derivatives.

Short-Term Autonomic Denervation of the Atria Using Botulinum Toxin

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. Materials and Methods Eight mongrel dogs were studied. The RA-PV and LA-IVC fat pads were exposed through a median thoracotomy. Botulinum toxin (BT, 50 U to each fat pad, n=6) or normal saline (NS, n=2) was injected in the entire area of two fat pads. The study protocol was applied before injection and repeated at 1, 2, 3, 4, and 5 hours thereafter. The sinus rate, ventricular rate during rapid atrial pacing with a cycle length of 50 ms, and AF inducibility were measured with and without vagal stimulation (VS). Bilateral cervical VS was applied (20 Hz, 0.2 ms, 5.6±2.0 V). AF inducibility was evaluated with burst pacing with 200 impulses at a 50-ms cycle length. Results VS effects on the sinus node and AF inducibility were eliminated a few hours after injection of BT; these changes were not observed after injection of NS. Conclusion Short-term autonomic denervation of the atria was achieved by blocking the major epicardial GP with BT.

Successful Management of Mechanical Complications Following Acute Myocardial Infarction -A Case Report-

Rupture of the heart as a complication of myocardial infarction is one of the most common causes of in-hospital mortality. Rupture of the free wall of the ventricle or interventricular septum has a poor prognosis when treated conservatively. So, rupture of the heart after infarction requires prompt diagnosis and early surgical repair despite the high overall incidence of early operative mortality before hemodynamic deterioration and multiorgan failures develop. Rupture of the left ventricle results in pseudoaneurysm if the overlying pericardium adhers to the surface of the heart. Pseudoaneurysms which rarely develop after infarction, tend to rupture. Their presence alone is an indicator for operation because of the very poor prognosis following rupture. We experienced successful management of 2 rare complications after acute myocardial infarction: ventricular septal defect and pseudoaneurysm. The first patient was a 49-year-old man who had an apical septal defect. His electrocardiogram showed Q wave in leads V2–V6, II, III, and aVF but a coronary angiogram showed normal findings. He was successfully treated by patch closure of the septal defect. The second patient was a 65-year-old female who had false aneurysm of the left ventricle. She had neither chest pain nor abnormality on the electrocardiogram. A coronary angiogram showed complete occlusion of the distal circumflex artery. Under cardiopulmonary bypass, the neck of the aneurysmal sac was successfully closed with a prolene suture.

Electrical transport properties of ZrFe2−xCrxHy

Abstract We have measured the electrical resistivity for ZrFe 2− x Cr x as a function of temperature between 20 K and 300 K. We have found that the dominant scattering mechanism for conduction electrons is changed from scattering by phonons to that due to the disordered atomic potentials as Cr composition is increased. We have also measured the thermoelectric power (TEP) for ZrFe 2− x Cr x and the hydrides of x = 0.6and1.5 as a function of temperature in the same range of temperature. For the alloys before hydrogenation, the non-linear temperature dependence of TEP is changed into the linear temperature dependence as Cr composition is increased. TEP for the hydride of x = 0.6and1.5 exhibits a positive hump at low temperatures. From these results, we have found that the hydrogen plays the role of an attractive scattering centre for the conduction electrons.