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Biomedical subjects

W Chua

Publications and source records attributed to W Chua.

13 recordsLinked to original sources
PubMed2005

Utility of the Health Belief Model in predicting compliance of screening in patients with chronic hepatitis B.

BACKGROUND: Regular surveillance is recommended for patients with chronic hepatitis B, to select candidates for anti-viral therapy and detect early complications. However, factors that determine compliance are not well studied. AIM: To determine the utility of the Health Belief Model in explaining non-compliance, among a group of chronic hepatitis B patients for screening. METHODS: A total of 192 chronic hepatitis B patients who responded to advertisement for free screening took part in a telephonic interview study. Subjects were asked about the five constructs of the Health Belief Model, and factors associated with recent screening were analysed. RESULTS: The mean age of the subjects was 42.1 +/- 0.7 years; 77% white male, and 97% Chinese. About 108 patients (56%) had recent screening. At multivariate analysis, only the ability to remember date of follow-up (OR: 4.37; 95% CI: 2.07-9.17) and the perception of having to wait a long time for venepuncture (OR: 0.38; 95% CI: 0.19-0.79) were significantly associated with recent screening. CONCLUSION: Future public health measures should include improving the logistics of follow-up procedures and providing reminders for screening to improve compliance.

Adult↗
PubMed2004

The majority of hepatitis B carriers are not on regular surveillance in Singapore.

INTRODUCTION: Carriers of hepatitis B virus (HBV) are at risk of developing long-term complications. Regular surveillance helps detect treatable chronic hepatitis, cirrhosis and liver cancer, and is recommended by practice guidelines in the United States, Europe and Singapore. However, there have been few studies evaluating the follow-up of HBV carriers. This study seeks to determine the proportion of HBV carriers on regular follow-up in Singapore and the impact on hepatitis B disease. METHODS: An advertisement was taken in local newspapers advertising for free screening to HBV carriers. 387 persons answered the advertisement. The screening comprised history-taking, physical examination, blood tests (liver panel, alphafoetoprotein, hepatitis B surface antigen (Ag) and hepatitis B eAg) and ultrasonography of liver. Further evaluation was conducted if the screening results were abnormal. RESULTS: Of the 387 HBV carriers, 346 (89 percent) were male and 375 (97 percent) were Chinese. Their mean age was 39 years (range 20-60 years) and 36 percent were positive for HBeAg. 247 (64 percent) were not on regular screening over the past 12 months. 19 (5.4 percent) patients were diagnosed to have complications, namely: 13 had HBeAg-positive chronic hepatitis, two had HBeAg-negative chronic hepatitis, one had early liver cancer who recovered well after a curative resection and three had compensated cirrhosis. CONCLUSION: Our screening programme diagnosed 5.4 percent of complications among 387 asymptomatic HBV carriers. However, 64 percent of the study subjects were not screened regularly and may pose an important public health threat if they develop long-term complications. Further studies are needed to evaluate and improve patient compliance for screening.

Adult↗
PubMed1994

Obstructive sleep apnea. Treatment improves quality of life--and may prevent death.

Obstructive sleep apnea syndrome may be just an annoyance to an affected person's bed partner, or it can be a more serious and even dangerous condition for the person involved. One clue to the condition is daytime somnolence, although not all sleepy patients have the syndrome. If obstructive sleep apnea syndrome is confirmed by a polysomnogram, a trial of nasal continuous positive airway pressure (NCPAP) is warranted. If daytime somnolence is unaffected, then it is unlikely that the syndrome is the sole cause of the patient's sleepiness. Alternative diagnoses (eg, narcolepsy, atypical depression) should then be considered. Surgery, orthodontic devices, and pharmacotherapy are generally less effective than NCPAP and are usually reserved for patients who cannot tolerate NCPAP. Surgical techniques may be best suited for patients who have clearly defined craniofacial abnormalities and those who cannot tolerate NCPAP. Weight reduction to near ideal body weight and avoidance of benzodiazepines, opiates, and alcohol should be emphasized in all patients with suspected or confirmed sleep apnea.

Humans↗
PubMed1987

Falsely elevated CSF total protein due to carryover in a discrete analyzer (Beckman Astra-8).

Falsely elevated values for CSF total protein, as determined in the Beckman Astra-8 Total Protein Module, were shown to be due to a combined effect of sample cross-contamination and reaction cup contamination by serum samples on the same sample tray. Normal CSF may be misdiagnosed as having an abnormally high protein concentration, due to this interference by normal serum samples. To avoid this carryover phenomenon, it is recommended that 3 saline samples be analysed for total protein before the analysis of the CSF samples; alternatively, all the CSF samples should be analysed separately in one batch.

Cerebrospinal Fluid Proteins↗
PubMed1986

Programmed electrical stimulation to determine the need for antiarrhythmic therapy in patients with complex ventricular ectopic activity.

Patients with complex ventricular ectopy (greater than or equal to Lown grade III) and organic heart disease (OHD) are at increased risk for sudden cardiac death. Despite this fact, many such patients will remain free of symptomatic ventricular arrhythmia and thus are unnecessarily exposed to antiarrhythmic drug toxicity and arrhythmic potentiation. Programmed stimulation (PS) was used to direct therapy in 88 patients with asymptomatic ventricular ectopy complicating OHD. Thirty-three had inducible ventricular tachycardia (VT) and underwent treatment. The 55 patients without inducible VT (less than or equal to 6 repetitive ventricular responses) are the focus of this study. Three patients required treatment for persistent cardiac awareness. The remaining 52 have been followed for 22 months off antiarrhythmic drugs and all have remained free of subsequent major arrhythmic events. Therefore, in patients with complex ventricular ectopy, OHD, and absence of prior symptomatic ventricular arrhythmia, PS identifies patients at low risk for future disabling or life-threatening arrhythmic episodes and patients with absence of inducible VT can usually be managed without antiarrhythmic drugs.

Adult↗
PubMed1984

A study of a Caucasian family with variant von Willebrand's disease in association with vascular telangiectasia and haemoglobinopathy.

A family was identified which carries multi-haematological disorders including Type IIA von Willebrand's disease, vascular telangiectasia, and a haemoglobinopathy (haemoglobin S trait). In the affected individuals, the von Willebrand's disease varies in its expression from an asymptomatic form to a severe form especially in those patients with telangiectasia. Some patients have vascular telangiectasia in the mucous membranes of the mouth and lips. In two patients endoscopy disclosed telangiectasia in the mucous membranes of the gastrointestinal tract. All of the patients who had telangiectasia also had von Willebrand's disease. An incidental finding was the presence of an abnormal haemoglobin (haemoglobin S) in some family members. The pattern of inheritance of the haemoglobinopathy was unrelated to the inheritance pattern of von Willebrand's disease. The presence of haemoglobin S did not interfere with the aggregation of platelets in response to ristocetin.

Adult↗
PubMed1977

The syndrome of normal electrocardiograms, accessory pathways and paroxysmal tachycardias.

Tachycardias may be associated with the pre-excitation syndrome, a short PR interval or a prolonged QT interval. This report describes seven patients whose electrocardiograms (ECGs) did not reveal any of the above-named conditions. All of the patients presented with syncopal episodes, and the history of palpitations was elicited in five of the patients. His bundle electrogram studies in all of the patients showed an essentially unchanged AH interval with atrial pacing rates up to 180 beats/min. This can only be explained by a total bypass of the AV node. Two of the patients were also paced from the ventricle, and an unchanged pacing stimulus to A wave interval was observed. This signifies in these patients a functioning bypass pathway in the retrograde direction as well. Thus it would appear that pre-excitation cannot by eliminated as a diagnostic possibility even if the ECG is normal.

Aged↗
PubMed1977

Electrophysiological properties of phentolamine in man.

The effects of phentolamine, 0-3 mg/min given intravenously for 15 minutes, on His bundle electrograms were studied in 11 patients with heart disease. Recordings were made at varied heart rates, using atrial pacing. Phentolamine significantly reduced the AH interval in every patient but it had no effect on the HV interval. Functional and effective refractory periods were measured with the use of the atrial extrastimulus technique. The effective refractory period of the atrium and atrioventricular node as well as the functional refractory period of the atrioventricular node all significantly decreased after phentolamine infusion. This improvement in conduction is probably mediated by a release of catecholamines.

Adolescent↗
PubMed1977

Fibroplastic parietal endocarditis with eosinophilia.

A 44-year-old woman with marked eosinophilia, leukocytosis, congestive heart failure, and the murmur of mitral stenosis had a restrictive type of pulse contour at cardiac catheterization. A right atrial angiogram revealed a huge right atrium, a small right ventricle, and a dilated contractile outflow tract consistent with the diagnosis of Loeffler's endocarditis. A marked conduction delay at the atrial level was demonstrated by His bundle electrogram studies.

Adult↗
PubMed1976

The effect of nitroglycerin on atrioventricular conduction in man.

His bundle electrograms were performed on 10 patients with organic heart disease. Six patients had had a recent myocardial infarction. Recordings were made at various rates utilizing right atrial pacing. Nitroglycerin, 1/150 gr, was administered to all 10 subjects, and the P-A, A-H, H-Q and H-S intervals were determined before, and immediately after the disappearance of the sublingually administered nitroglycerin. A significant decrease in the A-H interval occurred with negligible effects on the P-A, H-Q and H-S intervals. At the atrial pacing rate of 100/min, the average A-H interval fell from the control value of 152 msec to 129 msec after the administration of nitroglycerin (p less than 0.02); at the pacing rate of 130/min, the A-H interval decreased from 194 to 133 msec (p less 0.05). Second degree heart block occurred at higher pacing rates in six patients after nitroglycerin administration as compared to the control value. The average postsuppression sinoatrial recovery time control value of 1,083 msec decreased to 906 msec after nitroglycerin administration (p less than 0.01). These findings demonstrate that nitroglycerin can improve conduction through the A-V node.

Adult↗
PubMed1976

Hemodynamic effects of steroids in cardiac disease.

The hemodynamic effects of intravenous methylprednisolone were documented by right heart catheterization in seven patients with an acute uncomplicated transmural myocardial infarction 1 to 9 days after the onset of symptoms. Intracardiac pressures, brachial artery pressure, and cardiac output were determined before and 1 hour after the termination of the methylprednisolone infusion. Two grams of methylprednisolone were infused over a 20 minute period. The brachial pressure rose from a mean of 82 to 90 mm. Hq (N.S.). The brachial artery mean pressure fell in the one patient with a 1-day-old infarction, and it rose in the six patients with an older infarction, from 83 to 94 mm. Hg (p less than 0.01). As the brachial artery pressure rose in one patient, chest pain and marked ST-segment elevation occurred which were relieved by nitroglycerin. This experience promoted us to terminate the steroid study. There was a nonsignificant increase in the cardiac index and wedge pressure. The raise in the brachial artery pressure with an infarction older than 1 day was an unexpected finding, since steroids are presumed to be vasodilating agents.

Adult↗