Biomedical subjects

J G Cho

Publications and source records attributed to J G Cho.

24 records · Page 2Linked to original sources

PubMed1997

Atrial fibrillation in patients with permanent VVI pacemakers: risk factors for atrial fibrillation.

OBJECTIVES: Atrial fibrillation (AF) does not only deteriorate the cardiac function and increases the thromboembolic risk but also triggers rapid and irregular ventricular rhythm in patients with atrial synchronous pacing. However, the risk factors for the development of AF in patients with pacemakers are not clearly determined yet. The present study was designed to determine the risk factors for AF in patients with VVI pacemakers. METHODS: This study included 80 patients (41 sick sinus syndrome, 39 AV block) who were followed for more than 6 months or developed AF regardless of the duration of follow-up after implantation of VVI pacemakers. Patients were divided into two groups according to whether or not AF developed during follow-up (mean: 25.7 +/- 2.5 months): group A developed AF and group B did not. The underlying arrhythmias, cardiovascular risk factors, left atrial size, characteristics of P wave were compared between the two groups. RESULTS: The mean age of the patients was 58.9 +/- 11.4 years and 28 (35%) were male. AF developed in 13 (16.3%) of 80 patients with VVI pacemakers. Sick sinus syndrome (SSS) as an underlying arrhythmia was significantly more frequent in group A than group B (84.6% vs. 44.8%, p < 0.01). P wave width was greater in group A (127.6 +/- 24.8 ms) than in group B (110.7 +/- 17 ms) (p < 0.05). There was, however, no significant difference in cardiovascular risk factors, left atrial size, P wave axis and amplitude between the two groups. CONCLUSION: These results suggest that sinus node dysfunction and intra-atrial conduction delay may be the risk factors for AF in patients with VVI pacemakers. Further studies are needed to determine how sick sinus syndrome and intra-atrial conduction delay increase the risk for AF in patients with VVI pacemakers.

Adult↗

PubMed1996

Tsutsugamushi myocarditis with congestive heart failure and persistent atrial standstill.

Acute infectious myocarditis is primarily by viruses and bacteria, but sometimes by rickettsia. Tsutsugamushi disease is a febrile illness caused by Rickettsia tsutsugamushi, and has been prevalent in Korea since 1985. Characteristics of tsutsugamushi disease are fever, rash and eschar. Tsutsugamushi myocarditis is rare. Cardiac involvement may include ST-T changes, PR prolongation, mild mitral regurgitation, and perivascular inflammation with myocardial necrosis. We describe here a 50-year-old woman who complained of fever, orthopnea and chest pain. Work-up of the patient revealed abdominal scar, positive tsutsugamushi antibody, congestive heart failure with severe mitral and tricuspid regurgitation, persistent atrial standstill on electrophysiologic study, junctional rhythm and ST-T changes mimicking anterior myocardial infarction and myocardial inflammation with perivasculitis on endomyocardial biopsy. The patient's condition improved with doxycycline and inotropics. Persistent atrial standstill during was found at the one-year follow-up.

Arrhythmias, Cardiac↗

PubMed1996

Head-up tilt test with isoproterenol provocation in syncope of unknown origin.

OBJECTIVES: Head-up tilt test (HUT) has been reported to be useful in the evaluation of syncope of unknown origin (SUO). However, the sensitivity of HUT with no pharmacologic provocation was relatively low and variable, ranging 32 approximately 70%. Therefore, several protocols of HUT with different degrees and durations of the tilt and modes of provocation were proposed. The purpose of this study was to determine the value of the multi-stage head-up tilt test with isoproterenol provocation (HUT-isp) in the evaluation of SUO and drug efficacy. METHODS: Sixty-seven patients presenting with SUO and 30 control subjects with no history of syncope underwent the HUT-isp. Blood pressure (BP) was measured every 2 min and whenever the patient complained of any symptom, and cardiac rhythm was continuously monitored. The HUT-isp consisted of 3 stages: first for 20 min with no provocation, second and third stages with infusion of isoproterenol for 10 min each at a rate of 2 micrograms/min and 5 micrograms/min, respectively. A positive HUT-isp was defined when syncope or presyncope was reproduced, accompanied by hypotension (< 80 mmHg) or bradycardia (< 40/min) or both, and positive responses were classified into vasodepressive, cardioinhibitory and mixed type. RESULTS: The HUT-isp was positive in 56 (83.6%) of 67 patients with SUO and 10 (33.3%) of 30 control subjects. The type of positive responses was vasodepressive in 41 (73.2%), cardioinhibitory in 4 (7.1%) and mixed in 11 (19.6%). The sensitivity of the HUT-isp in diagnosing vasovagal syncope was 83.6%, specificity 66.7% and positive predictive value 84.8%. Positive responses were developed most frequently in the 3rd stage: 76.8% in patients, 70% in controls. The effect of 3 drugs (carteolol, aminophylline and disopyramide) was evaluated in 27 patients with a repeat HUT-isp. Carteolol was effective in 12 (85.7%) of 14 patients, disopyramide in 7 (58. 3%) of 12 and aminophylline in 1 (14.3%) of 7. During the follow-up period of 175 +/- 212 days (26 approximately 623 days), none of the 20 patients with a negative repeat HUT-isp developed a recurrent syncope. CONCLUSION: The HUT-isp is thought safe and useful to evaluate syncope of unknown origin and to guide effective drug therapy.

Adult↗

PubMed1994

Effects of incremental doses of procainamide in patients with sustained uniform ventricular tachycardia.

INTRODUCTION: Although intravenously administered procainamide has been used extensively during electropharmacologic testing for more than 10 years, there is little information available on the effects of incremental dosing of procainamide in patients with inducible, monomorphic ventricular tachycardia (VT). METHODS AND RESULTS: Twenty-nine patients with coronary artery disease had sustained monomorphic VT reproducibly induced in the baseline, drug-free state. Programmed stimulation was repeated 5 minutes after loading infusion (50 mg/min) of 7.5 and 15 mg/kg (all patients) and 22.5 mg/kg of procainamide (15 patients), while maintaining continuous infusion of 0.055, 0.11, and 0.165 mg/kg per minute after each increment in dose, respectively. Corresponding procainamide plasma concentrations were 5.6 +/- 2, 10.5 +/- 3, and 14.5 +/- 3 mg/L before, and 4.7 +/- 2, 9.6 +/- 3, and 14.6 +/- 4 mg/L after electrophysiologic study at each increment in dose of procainamide, respectively. Each incremental dose of procainamide resulted in significant prolongation of tachycardia cycle length and QRS duration during sinus rhythm and right ventricular pacing. Five (17%), 7 (24%), and 1 (7%) patients, respectively, had no inducible sustained VT following the incremental dosing of procainamide. Three of five patients who had no inducible VT at 7.5 mg/kg had VT induced again at a higher dose of procainamide. Four of 24 patients whose VT remained inducible at 7.5 mg/kg of procainamide had no VT induced at 15 mg/kg of procainamide. Twelve (41%), 15 (52%), and 6 (40%) patients, respectively, no longer had VT with baseline morphology induced following the incremental dosing of procainamide. VT with new morphology compared to baseline was induced in more than 40% of patients at one or more of the three different procainamide dosing regimens. The mean cycle length of VTs with new morphology was significantly shorter than the cycle length of tachycardias with baseline morphology at each particular dose of procainamide. CONCLUSION: Similar serum procainamide concentrations before and after programmed stimulation can be achieved at the described dosing regimen. Although 7.5 and 15 mg/kg of procainamide are both effective in suppressing induction of all VT in 20% to 25% of patients, non-inducibility at a particular dose of procainamide does not predict noninducibility at a respectively higher or lower dose. New morphologies of VT that are frequently faster than VTs with baseline morphology at a particular dose of procainamide can be induced in approximately half of the patients, and the clinical significance of these arrhythmias remains to be determined.

Adult↗

PubMed1993

Early outcome of PTCA in totally occluded coronary arteries.

BACKGROUND: Since percutaneous transluminal coronary angioplasty (PTCA) was first introduced in 1977 by Gruentzig as a treatment for proximal short-segmental, non-calcified, concentric isolated coronary stenosis, it has been used with increasing frequency in patients of symptomatic coronary artery disease with broader indications, including patients with multi-vessel disease, unstable angina, acute myocardial infarction and totally occluded coronary arteries. Among these, total coronary occlusion constitutes a subdivision with specific features that require separate evaluation. The purpose of this study was to determine the initial results of PTCA for total coronary occlusion. METHODS: Thirty-five patients with manifested ischemic heart disease with totally occluded coronary arteries, documented by coronary angiography, underwent recanalization procedure by PTCA between Jan. 1990 and Oct. 1991. RESULTS: Thirty-five patients were comprised of 20 acute myocardial infarction (MI), 7 old MI and 8 unstable angina. Eighteen (50.1%) patients had one major atherosclerosis risk factor and 10 (29.4%) had two or more. PTCA for total coronary artery occlusion was attempted in the left anterior descending artery (LAD) in 16 patients, right coronary artery (RCA) in 11, left circumflex artery (LCx) in 2 and protected left main in one. PTCA was successful in 23 patients (66%): LAD in 11/18 (61%) and RCA 11/14 (79%), showing significantly higher success rate with RCA than LAD (p < 0.05). Primary success rate of PTCA in accordance with the duration of the total occlusion estimated on the basis of clinical and angiographic data was 71% (15/21) when less than two weeks, 63% (5/8) when between 2 to 12 weeks, and 50% (3/6) longer than 12 weeks. Mean duration of the total occlusion in successful PTCA was 1.4 months (range; 10 days-5 months) and, 1.7 months (range; 3 weeks-3 years) in failed PTCA. Diameter stenosis of the lesions was significantly decreased from 100% to 19.7% after successful PTCA. There was no death but 2 patients were complicated with coronary artery embolization occluding major distal branches. CONCLUSION: The study suggested that PTCA of total coronary artery occlusion can be performed safely and effectively in selected cases and might be more successful in the lesion with shorter duration of occlusion.

Adult↗

PubMed1989

Suprasternal M-mode echocardiography of the right pulmonary artery as a model for investigation of pulmonary hemodynamics in essential hypertension.

The right pulmonary artery (RPA) dimensions of 85 asymptomatic mild or moderate hypertension (HT) patients, divided into 6 subgroups according to the left ventricular (LV) mass index (125g/m2 BSA) left atrial (LA) dimension index (2.2cm/m2 BSA), and 40 normal subjects were studied utilizing suprasternal M-mode echocardiography in order to examine the consistency of the elevated PA pressure in essential HT and to understand its pathogenesis. The RPA dimension at late diastole, at the end of the right ventricular isovolumic contraction, and at systole in the subgroup of HT without LV hypertrophy and LA enlargement was significantly increased compared with those of the normal group (18.4 +/- 2.8 vs 16.2 +/- 2.3mm, 19.6 +/- 3.0 vs 17.2 +/- 1.3mm, 22.5 +/- 2.5 vs 20.8 +/- 1.9mm, p less than 0.05, respectively) and varied in close correlation with systolic and diastolic BP and the dimension of the aorta. The dimensions in the other 5 subgroups were the same and were not further affected by the LV mass and LA dimension. The above results suggest that elevated systemic BP per se is associated with the dilation of the RPA supposedly caused by increased PA resistance, besides the backward effect of the increased LV and/or LA pressure which may affect the increase of PA pressure.

Adult↗