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Biomedical subjects

Hung-Fat Tse

Publications and source records attributed to Hung-Fat Tse.

At least 19 recordsLinked to original sources
PubMed2006

Impaired nitrate-mediated dilatation could reflect nitrate tolerance in patients with coronary artery disease.

AIM: To investigate whether nitrate-mediated dilatation (NMD) of the brachial artery could be impaired by the use of nitrates and reflect nitrate tolerance in coronary artery disease (CAD) patients. METHODS: A total of 243 patients (mean age 61+/-12 years, 146 male) were recruited before coronary angiography. Gensini score was calculated to assess the severity of CAD. Flow-mediated dilatation (FMD) and NMD of the brachial artery were measured. RESULTS: NMD progressively decreased from subjects without CAD (control group, n=71) to non-nitrate users (n=64) and nitrate users (n=108) with CAD (16.2+/-6.01% versus 13.4+/-5.57% versus 9.57+/-4.52%, P<0.001 for all). Multiple linear regression analysis showed that age, FMD, diameter of the brachial artery, hypertension, and nitrate use were independent determinants of NMD. In subgroup analysis of patients with high Gensini score (>10), nitrate users (n=56, 9.00+/-4.00%) had a significant lower NMD than non-users (n=28, 12.4+/-5.45%, P<0.001), but no difference in other parameters including age, prevalence of hypertension, FMD, Gensini score and use of other medications. CONCLUSIONS: The use of nitrates independently impaired NMD in CAD patients. An impaired NMD could be a comprehensive index of nitrate tolerance in patients with CAD.

Adult↗
PubMed2006

Emerging trends of community acquired infective endocarditis.

BACKGROUND: To obtain epidemiological information and to evaluate the emerging trend of incidence and clinical features of community acquired infective endocarditis (IE) in Hong Kong. METHODS: Population-based survey in a regional hospital in Hong Kong which served 0.55 million population over an 11-year period was conducted. 172 patients diagnosed to have IE between 1995 and 2005 were analyzed. Incidence, underlying heart disease, causative microorganisms and clinical outcomes of IE were studied. RESULTS: The standardized annual incidence of community acquired IE was 2.8 cases per 100,000 person-year and remain stable over the past 10 years in Hong Kong (P=0.57 for trends). The most common underlying heart diseases for IE were intravenous drug addict (30%), followed by chronic rheumatic heart disease (18%). There was a time trend of increasing age in patients suffered from IE, both in patients with or without intravenous drug abuse (overall P=0.004). Although there were no significant changes in the overall proportion of IE patients with different underlying etiologies, site of IE involvement and types of microorganisms, non-addict patients showed an increasing trend of staphylococcal IE during the study period (P=0.01). The adverse clinical outcome of IE during the study period remained unchanged (P=0.71). CONCLUSIONS: The results of this study have demonstrated that IE continued to be an important disease with stable incidence and high morbidity and mortality over time in Asia. Furthermore, our study also highlighted that IE is an emerging disease with continuously changing clinical and microbiologic patterns, and significant differences are still present between different countries.

Community-Acquired Infections↗
PubMed2006

A patient with relapsing pacemaker infection due to "Gram-positive bacilli".

Mycobacterium fortuitum infection of pacemaker system is rarely encountered in clinical practice. We reported a case of relapsing M. fortuitum infection of pacemaker system associated with endocarditis which had been erroneously diagnosed to be Gram-positive bacilli. The diagnosis was finally confirmed by detail histological and microbiological examination. This case clearly demonstrated that incomplete removal of pacemaker system resulted in relapsing infection despite appropriate antibiotic therapy.

Aged↗
PubMed2006

Incidence, clinical characteristics and outcome of congestive heart failure as the initial presentation in patients with primary hyperthyroidism.

BACKGROUND: There are limited systematic data on the incidence, clinical characteristics and outcomes of congestive heart failure (CHF) in patients with hyperthyroidism. The aim of this study was to investigate the incidence, clinical characteristics and outcome of CHF as the initial presentation in patients with primary hyperthyroidism. METHODS: The prevalence, clinical characteristics and outcome of CHF was studied in 591 consecutive patients (mean (SD) age 45 (1) years, 140 men) who presented with primary hyperthyroidism. RESULTS: CHF was the presenting condition in 34 patients (5.8%) with hyperthyroidism. The presence of atrial fibrillation at presentation (OR 37.4, 95% CI 9.72 to 144.0, p<0.001) was an independent predictor for the occurrence of CHF. Of the 34 patients with CHF, 16 (47%) had systolic left ventricular dysfunction with left ventricular ejection fraction (LVEF)<50%. They were predominantly male (OR 26.6, 95% CI 2.6 to 272.5, p = 0.006) and had a lower serum thyroxine level (OR 0.93, 95% CI 0.87 to 0.99, p = 0.044) than patients with preserved left ventricular systolic function. In these patients, LVEF (55 (4)% vs 30 (2)%, p<0.001) and New York Heart Association functional class (1.2 (0.1) vs 2.5 (0.2), p<0.001) improved significantly 3 months after achieving euthyroid status. Systolic left ventricular dysfunction (mean (SD) LVEF 38 (4)%) persisted on long-term follow-up in five PATIENTS: no clinical parameter could be identified to predict the occurrence of this persistent cardiomyopathy (p>0.05). CONCLUSION: CHF was the initial clinical presentation in approximately 6% of patients with hyperthyroidism, and half of them had left ventricular systolic dysfunction. Symptoms of CHF subsided and LVEF improved after treatment for hyperthyroidism. Nonetheless, one-third of these patients developed persistent dilated cardiomyopathy.

Adolescent↗
PubMed2006

Bioartificial sinus node constructed via in vivo gene transfer of an engineered pacemaker HCN Channel reduces the dependence on electronic pacemaker in a sick-sinus syndrome model.

BACKGROUND: The normal cardiac rhythm originates in the sinoatrial (SA) node that anatomically resides in the right atrium. Malfunction of the SA node leads to various forms of arrhythmias that necessitate the implantation of electronic pacemakers. We hypothesized that overexpression of an engineered HCN construct via somatic gene transfer offers a flexible approach for fine-tuning cardiac pacing in vivo. METHODS AND RESULTS: Using various electrophysiological and mapping techniques, we examined the effects of in situ focal expression of HCN1-DeltaDeltaDelta, the S3-S4 linker of which has been shortened to favor channel opening, on impulse generation and conduction. Single left ventricular cardiomyocytes isolated from guinea pig hearts preinjected with the recombinant adenovirus Ad-CMV-GFP-IRES-HCN1-DeltaDeltaDelta in vivo uniquely exhibited automaticity with a normal firing rate (237+/-12 bpm). High-resolution ex vivo optical mapping of Ad-CGI-HCN1-DeltaDeltaDelta-injected Langendorff-perfused hearts revealed the generation of spontaneous action potentials from the transduced region in the left ventricle. To evaluate the efficacy of our approach for reliable atrial pacing, we generated a porcine model of sick-sinus syndrome by guided radiofrequency ablation of the native SA node, followed by implantation of a dual-chamber electronic pacemaker to prevent bradycardia-induced hemodynamic collapse. Interestingly, focal transduction of Ad-CGI-HCN1-DeltaDeltaDelta in the left atrium of animals with sick-sinus syndrome reproducibly induced a stable, catecholamine-responsive in vivo "bioartificial node" that exhibited a physiological heart rate and was capable of reliably pacing the myocardium, substantially reducing electronic pacing. CONCLUSIONS: The results of the present study provide important functional and mechanistic insights into cardiac automaticity and have further refined an HCN gene-based therapy for correcting defects in cardiac impulse generation.

Animals↗
PubMed2006

Incidence and predictors of upper gastrointestinal bleeding in patients receiving low-dose aspirin for secondary prevention of cardiovascular events in patients with coronary artery disease.

AIM: The use of low-dose aspirin to prevent cardiovascular disease events is well established. However, the incidence and predictors of upper gastrointestinal bleeding (UGIB) with its use are unknown. We studied prospectively the incidence and outcome of peptic ulceration in low-dose aspirin users. METHODS: A total of 991 patients with coronary artery disease (CAD) on low-dose aspirin were prospectively followed-up for two years for the occurrence and clinical features of first hospitalized episode of UGIB. RESULTS: UGIB had a bimodal presentation with 45% occurring within four months of aspirin initiation and had an overall prevalence of 1.5% per year. There was no UGIB-related death. Hypertension (OR = 4.6, 95%CI 1.5-14.7, P = 0.009), history of peptic ulceration (OR = 3.1, 95%CI 1.1-9.0, P = 0.039), tertiary education (OR = 3.08, 95%CI 1.1-9.0, P = 0.039) and higher lean body mass (P = 0.016) were independent factors associated with UGIB. Use of nitrate did not reduce UGIB. CONCLUSION: The incidence of UGIB in patients with CAD on long-term low-dose aspirin is low, but is accompanied with significant morbidity. With prolonged use of aspirin, UGIB continues to be a problem for those with risk factors and especially in patients with a history of peptic ulcers, in which UGIB tends to occur early after aspirin therapy.

Aged↗
PubMed2006

Safety of catheter-based intramyocardial autologous bone marrow cells implantation for therapeutic angiogenesis.

The long-term safety and efficacy of autologous bone marrow cell implantation into the myocardium remains undefined. We studied the long-term clinical outcome of 12 patients with severe coronary artery disease who underwent electromechanical mapping-guided catheter-based autologous bone marrow cell implantation. Magnetic resonance imaging at 3 and 6 months showed no evidence of intramyocardial tumor formation, myocardial damage, or worsening of left ventricular ejection fraction. No sustained arrhythmia was detected on 24-hour Holter monitoring. After 44 +/- 10 months of follow-up, 1 patient had died of stroke at 8 months and another patient had died of myocardial infarction at 20 months. Computed tomography at 36 months or postmortem examination showed no tumor formation or intramyocardial calcification at the treated sites, and no sustained ventricular arrhythmia or sudden death was observed. Autologous bone marrow cell implantation into the ischemic human myocardium was not associated with long-term major adverse events regarding tumor, scar, or calcification formation, and the arrhythmogenic risk was low.

Aged↗
PubMed2006

Effects of oral arsenic trioxide therapy on QT intervals in patients with acute promyelocytic leukemia: implications for long-term cardiac safety.

Ventricular tachyarrhythmias may occur during intravenous arsenic trioxide (As2O3). This has not happened during oral As2O3. Sixteen patients were studied by electrocardiography and 24-hour Holter monitoring at baseline, during and after oral As2O3 (As2O3-ON, As2O3-OFF). QT and corrected QT (QTc) were significantly longer during As2O3-ON than in As2O3-OFF, but QT and QTc dispersions were comparable. The patients' 24-hour heart rates were higher during As2O3-ON than in As2O3-OFF. QTc intervals at each hour were longer during As2O3-ON than in As2O3-OFF. However, QTc prolongation of more than 30 milliseconds only occurred at one time point (2 hours) after oral As2O3, resulting in QTc of more than 500 milliseconds in 3 of 16 patients, all within 4 hours of oral As2O3. Although the standard deviation of normal RR interval was lower during As2O3-ON, ratios of low frequency to high frequency power for As2O3-ON and As2O3-OFF were comparable. No ventricular proarrhythmias were observed. These observations, due to the lower peak plasma arsenic reached during oral As2O3, may explain the relative cardiac safety of oral As2O3.

Administration, Oral↗
PubMed2006

Ion channels in mesenchymal stem cells from rat bone marrow.

Mesenchymal stem cells (MSCs) from bone marrow are believed to be an ideal cell source for cardiomyoplasty; however, cellular electrophysiology is not understood. The present study was designed to investigate ion channels in undifferentiated rat MSCs. It was found that three types of outward currents were present in rat MSCs, including a small portion of Ca(2+)-activated K(+) channel (I(KCa)) sensitive to inhibition by iberiotoxin and/or clotromazole, a delayed rectifier K(+) current (IK(DR)), and a transient outward K(+) current (I(to)). In addition, tetrodotoxin (TTX)-sensitive sodium current (I(Na.TTX)) and nifedipine-sensitive L-type Ca(2+) current (I(Ca.L)) were found in a small population of rat MSCs. Moreover, reverse transcription-polymerase chain reaction revealed the molecular evidence of mRNA for the functional ionic currents, including Slo and KCNN4 for I(KCa); Kv1.4 for I(to); Kv1.2 and Kv2.1 for IK(DR); SCN2a1 for I(Na.TTX); and CCHL2a for I(Ca.L). These results demonstrate for the first time that multiple functional ion channel currents (i.e., I(KCa), I(to), IK(DR), I(Na.TTX), and I(Ca.L)) are present in rat MSCs from bone marrow; however, physiological roles of these ion channels remain to be studied.

Adipogenesis↗
PubMed2006

Prediction of aortic augmentation index using radial pulse transmission-wave analysis.

OBJECTIVE: Current arterial transfer functions have low capability in predicting aortic augmentation index (AIx) from radial pulse contour (RPC), because of the difficulty in accurately identifying the merging point (inflection point) in the derived aortic pulse contour (APC). We hypothesize that the formation time between each characteristic wave in APC is about one-third of ejection duration (ED/3). We sought to assess the accuracy of ED/3 in identifying the merging point in APC as compared to the conventional differential method. In addition, we sought to derive the AIx from RPC based on an arterial transfer function and the ED/3 method. METHODS: APC and RPC sequences were measured digitally and simultaneously in 60 subjects (37 males; aged 60 +/- 10 years). An ensemble-averaged RPC-to-APC transfer function was determined from 30 randomly selected subjects and was used to derive APC sequences in the 30 additional subjects. The accuracy of AIx predicted from RPC was determined. RESULTS: In patients with a clearly identifiable merging point in APC, the ED/3 method identified the merging point of measured APC within 1.97 +/- 0.60 ms of that identified by the conventional differential method, with identical AIx. The AIx and merging point of derived APC using the ED/3 method were also within 0.22 +/- 1.01% and 1.81 +/- 1.64 ms, respectively, of those of the measured APC using the conventional differential method. The accuracy of the predicted AIx was independent of age, sex, body-mass index and presence of hypertension. CONCLUSION: In a quiet resting state, the ED/3 is an alternative method for identifying the merging point in APC. In conjunction with transfer-function technique, AIx can be derived accurately from RPC.

Adult↗
PubMed2006

Endocardial visualization of esophageal-left atrial anatomic relationship by three-dimensional multidetector computed tomography "navigator imaging".

BACKGROUND: The close proximity of left atrium (LA) and esophagus during radiofrequency ablation for atrial fibrillation (AF) predisposes to thermal injury resulting in atrio-esophageal fistula. This work proposes to study the anatomic relationship between the esophagus and the LA wall using multidetector computed tomography (MDCT) three-dimensional (3D) "Navigator" reconstruction technique. METHODS: Forty-five consecutive patients (37 men, mean age 52.7+/-14.1 years) with preradiofrequency ablation MDCT scans of the thorax for AF were recruited. Length and type (continuous or interrupted) of fat pad between esophagus and LA were evaluated. The position, width, and length of the esophagus in contact (without fat pad) with the LA were determined by using "Navigator" software on the endocardial view of LA. RESULTS: The fat pad was continuous in 4% (2 of 45) and interrupted in 96% (43 of 45) patients. The mean width and length of esophageal-LA contact in 43 cases with interrupted fat pad was 24.0+/-5.8 mm (range 10.5-35.3 mm) and 41.9+/-11.6 mm (5.4-64 mm), respectively. There was an inverse relationship between the lengths of the esophageal-LA contact and the upper fat pad (r=-0.50, P=0.001). The esophagus was located to the left, right, and midline of the LA in 40, 2, and 1 patients, respectively, and the esophagus was in contact with and overrode the PV orifice in 22 and 4 patients, respectively. CONCLUSION: Direct esophageal-LA contact without the intervening fat pad was present in 96% of the cases, with 93% of esophagi lying to the left of the LA and 51% in contact with a PV orifice. Three-dimensional Navigator imaging technique has enhanced the visualization of the anatomical information of the esophagus, LA wall, and PV orifices that may be used to avoid thermal injury to the esophagus during LA ablation procedure.

Adult↗
PubMed2006

Avoidance of electromagnetic interference to implantable cardiovertor-defibrillator during atrioventricular node ablation for atrial fibrillation using transvenous cryoablation.

Transient or permanent malfunction of implantable device may result from electromagnetic interference during delivery of radiofrequency energy for treatment of cardiac arrhythmias. Therefore, there is a clinical need for an alternative energy source for cardiac arrhythmia ablation in patients with implantable device. This report presents a case of the absence of electromagnetic interference to an implantable cardioverter defibrillator during atrioventricular nodal ablation for atrial fibrillation to avoid inappropriate shock.

Aged↗
PubMed2005

The incremental benefit of rate-adaptive pacing on exercise performance during cardiac resynchronization therapy.

OBJECTIVES: The purpose of this research was to investigate the effect of using rate-adaptive pacing and atrioventricular interval (AVI) adaptation on exercise performance during cardiac resynchronization therapy (CRT). BACKGROUND: The potential incremental benefits of using rate-adaptive pacing and AVI adaptation with CRT during exercise have not been studied. METHODS: We studied 20 patients with heart failure, chronotropic incompetence (<85% age-predicted heart rate [AP-HR] and <80% HR reserve), and implanted with CRT. All patients underwent a cardiopulmonary exercise treadmill test using DDD mode with fixed AVI (DDD-OFF), DDD mode with adaptive AVI on (DDD-ON), and DDDR mode with adaptive AVI on (DDDR-ON) to measure metabolic equivalents (METs) and peak oxygen consumption (VO2max). RESULTS: During DDD-OFF mode, not all patients reached 85% AP-HR during exercise, and 55% of patients had <70% AP-HR. Compared to patients with >70% AP-HR, patients with <70% AP-HR had significantly lower baseline HR (66 +/- 3 beats/min vs. 80 +/- 5 beats/min, p = 0.015) and percentage HR reserve (27 +/- 5% vs. 48 +/- 6%, p = 0.006). In patients with <70% AP-HR, DDDR-ON mode increased peak exercise HR, exercise time, METs, and VO2max compared with DDD-OFF and DDD-ON modes (p < 0.05), without a significant difference between DDD-OFF and DDD-ON modes. In contrast, there were no significant differences in peak exercise HR, exercise time, METs, and VO2max among the three pacing modes in patients with >70% AP-HR. The percentage HR changes during exercise positively correlated with exercise time (r = 0.67, p < 0.001), METs (r = 0.56, p < 0.001), and VO2max (r = 0.55, p < 0.001). CONCLUSIONS: In heart failure patients with severe chronotropic incompetence as defined by failure to achieve >70% AP-HR, appropriate use of rate-adaptive pacing with CRT provides incremental benefit on exercise capacity during exercise.

Adaptation, Physiological↗
PubMed2005

Mast cell contributes to cardiomyocyte apoptosis after coronary microembolization.

Coronary microembolization (CME) is associated with progressive myocardial dysfunction despite restoration of coronary flow reserve (CFR). The potential pathophysiological role of mast cells (MCs) remains unclear. Therefore, we induced CME in 18 miniswines and determined whether MC accumulation occurs and their effects on local cytokine secretion [interleukin (IL)-6, IL-8, tumor necrosis factor-alpha (TNF-alpha)]; cardiomyocyte apoptosis; and collagen formation at day 1 (D1), day 7 (D7), and day 30 (D30) after CME. Four sham-operated animals without CME (controls) and six animals treated with a MC stabilization agent (tranilast) for 30 days after CME were also studied. CFR decreased at D1 but returned to baseline level at D7 and D30. Coronary sinus levels of IL-6, IL-8, and TNF-alpha increased significantly at D1 and D7 (p<0.01 vs baseline). Levels of IL-6 and IL-8 at D30 returned to baseline level, but not those of TNF-alpha. The numbers of total and degranulating MCs, % apoptotic cardiomyocytes, and collagen volume fraction (CVF) over CME myocardium at D1, D7, and D30 were significantly higher than controls (p<0.01). Treatment with tranilast significantly reduced the serum level of TNF-alpha, numbers of total and degranulating MCs, % apoptotic cardiomyocytes, and CVF at D30 (all p<0.05). There was a significant positive correlation between the numbers of MCs with % apoptotic cardiomyocytes (r = 0.77, p<0.001) and CVF (r = 0.75, p<0.001) over the CME myocardium. Despite restoration of CFR, cardiomyocyte apoptosis persisted after CME and was positively correlated with the number of MCs but was prevented with tranilast treatment. These findings suggest that MCs contribute to cardiomyocyte apoptosis after CME.

Animals↗