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T S Hsu

Publications and source records attributed to T S Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Noninvasive predictors of systemic embolism in mitral stenosis. An echocardiographic and clinical study of 500 patients.

Few predictors of systemic embolism in patients with mitral stenosis have been identified by noninvasive methods. This study used the most powerful noninvasive diagnostic tool, transthoracic echocardiography, as well as other noninvasive clinical information to look for predictors. Five hundred consecutive patients with a mitral valve area of 2 cm2 or less were studied. They were divided into two groups: group 1 consisted of 143 patients with a history of systemic embolism and group 2 consisted of 357 patients with no history of systemic embolism. Using a stepwise logistic regression on a random subsample of 400 patients, 4 independent predictors were found: the presence of atrial fibrillation (p = 0.003, relative risk [RR] = 2.3, 95% CI = 1.3, 4.2), the absence of significant tricuspid regurgitation (p = 0.008, RR = 2.5, 95% CI = 1.3, 4.9), the absence of aortic regurgitation (p = 0.022, RR = 2.2, 95% CI = 1.1, 4.2), and the presence of left atrial smoky echoes (p = 0.039, RR = 1.7, 95% CI = 1.1, 3.0). When the above model, together with significant interaction terms, was applied to the remaining 100 patients, both the Hosmer-Lemeshow and Brown goodness-of-fit statistics were not significant (p = 0.888 and p = 0.248, respectively), indicating that the fit was adequate and the model was validated. Thus, important noninvasive predictors of systemic embolism in patients with mitral stenosis can easily be obtained. Subgroups of patients with high risk of systemic embolism can be identified. This may refine our therapeutic strategies to prevent the catastrophe of systemic embolism.

Adolescent↗
PubMed1993

Diagnostic use of metoclopramide in hypertension caused by pheochromocytoma.

We studied 5-mg metoclopramide provocation in six pheochromocytomatous patients with different tumor locations, varying secretory patterns and large tumor sizes (> 12 g or equivalently) and in 14 patients with essential hypertension as part of diagnostic work-up, usually after screening with vanillylmandelic acid assay by the colorimetric method. Antihypertensive medication continued in three and five patients, respectively. Despite similar basal blood pressures patients with pheochromocytomas developed more prominent pressor responses in five of six patients than the nonpheochromocytomatous patients (P < 0.01), most (10) of the latter with negligible pressor responses. Basal plasma catecholamines were higher in each of the pheochromocytomatous patients of different secretory patterns. Further rises after provocation were seen in all pheochromocytomatous patients except one with early pressor response, and also in one nonpheochromocytomatous patient. All tests were well tolerated. Thus, we concluded that the metoclopramide test based upon joint pressor response and plasma catecholamine response can be safely used in the diagnosis of pheochromocytoma. A less stringent protocol including a short drug-off preparatory period may be a warranted compromise between feasibility and diagnostic accuracy.

Adrenal Gland Neoplasms↗
PubMed1993

Effect of mitral regurgitation and aortic regurgitation on Doppler-derived mitral orifice area in patients with mitral stenosis.

Traditional Doppler pressure half-time (T1/2) method (mitral valve area = 220/T1/2) is widely used for evaluating the mitral orifice area in patients with mitral stenosis (MS). However, the effect of mitral regurgitation (MR) and aortic regurgitation (AR) on the calculation of the mitral valve area by this method is still controversial. Therefore, we examined 493 consecutive patients with MS to evaluate the effect of MR and AR on Doppler-derived mitral orifice area. The mitral orifice area planimetered from two-dimensional echocardiogram was used as the standard reference. Excluding 16 patients with either unsatisfactory Doppler or echocardiographic tracings, 477 patients were enrolled in the study. There were 162 males and 315 females with a mean age of 49 years. They were divided into 4 groups: group A, 327 patients with MS but no MR and AR; group B, 68 patients with MS + MR but no AR; group C, 64 patients with MS + AR but no MR; group D, 18 patients with MS + MR + AR. The differences between echo and Doppler area were 0.02 +/- 0.02 cm2 (mean +/- SE), p = 0.220, in group A; 0.13 +/- 0.04 cm2, p = 0.004, in group B; 0.11 +/- 0.05 cm2, p = 0.026 in group C; and 0.31 +/- 0.08 cm2, p = 0.001, in group D. Thus, in patients with MS, the associated MR or AR may invalidate the pressure half-time method for the derivation of mitral valve area.

Adult↗
PubMed1992

In-utero sound levels when vibroacoustic stimulation is applied to the maternal abdomen: an assessment of the possibility of cochlea damage in the fetus.

OBJECTIVE: To measure sound pressure level in utero while a vibro acoustic stimulator is applied to maternal abdomen and to calculate whether the estimated effect on fetal cochlea cilia vibration would be hazardous. DESIGN: Prospective descriptive study. SETTING: Labour ward, National University Hospital, Singapore. SUBJECTS: Eight women undergoing induction of labour. INTERVENTION: A hydrophone was introduced via the cervix into the uterus and placed under ultrasound guidance near the fetal ear. Sound pressure was recorded when a vibroacoustic stimulator was applied directly to the maternal abdomen and also when separated by 2 cm of air. MAIN OUTCOME MEASURES: Sound pressure levels in utero. RESULTS: The sound level recorded from the vibrator diaphragm in air was 107 dB at 2 cm and 74 dB at 1 m. The mean sound pressure level in utero was 90.7 dB (range 75-96 dB) when the vibrator was in contact with the abdominal wall and 80.1 dB (range 70-88 dB) when separated by 2 cm of air. CONCLUSIONS: Analysis of factors affecting displacement of cochlear sensing cilia in utero show that, for equal sound pressures, sound intensity and sound vibration are about 4000 times less in amniotic fluid, compared to that produced in air. Further protection is provided by viscous and hydrodynamic features of the ear. The estimated effect on cilia vibration by the mean sound pressure registered in utero, about 90 dB, corresponds to that produced postnatally by an airborne sound registering about 40 dB, which would not be hazardous.

Cochlea↗
PubMed1991

Endpoints of treadmill exercise testing for functional evaluation of patients with mitral stenosis.

The study was performed on 122 patients proved by catheterization to have dominant mitral stenosis so as to define proper endpoints of exercise testing for functional evaluation. This represents the 14-year experience with mitral stenosis in our exercise laboratory. Of them, we investigated 126 who completed clinically event-free Naughton treadmill exercise tests. Excess peak exercise heart rates (over 150 beats per minute, 63%) and exertional hypotensive responses (59%, probably including factitious responses due to unreliable indirect pressure readings) did not correlate with the severity of mitral stenosis. Without limiting symptoms and major ventricular arrhythmias, either of the above as endpoints may cause the test to be halted prematurely in half the cases. Ventricular arrhythmias (60%; in complex forms, 20%; possibly contaminated by aberrancy in atrial fibrillation and aggravated by digitalis/diuretics) did not correlate with severity of stenosis either, but the only one major complication we met was secondary to ventricular tachyarrhythmia. Limiting symptoms (83%; of them 94% being dyspnea/fatigue correlating with severity at P less than 0.01) and complex ventricular arrhythmias as endpoints terminated 85% of the tests safely in this series. Atrial thrombuses (34%, all non-floating) did not cause any related complications. Thus, we concluded that limiting symptoms and complex ventricular arrhythmias are the proper endpoints in evaluating the exercise capacity of patients with mitral stenosis after prior echocardiographic exclusion of those with potentially risky floating thrombus.

Adolescent↗
PubMed1991

Vibroacoustic stimulation and intrauterine sound pressure levels.

The sound pressure level in amniotic fluid generated by vibroacoustic stimulation, assessed with a hydrophone placed close to the fetal head, was studied in 16 subjects. The mean recorded sound pressure level was 115 dB and the highest level was 129 dB. The range of the background noise was 63.5-80.5 dB. There was no obvious relationship between the distance from the stimulator to the hydrophone and the intrauterine sound pressure level. Although sound pressure levels are high, they are probably reduced before reaching the cochlea of the fetus because of the surrounding amniotic fluid and the fluid in the middle ear.

Acoustic Stimulation↗
PubMed1989

Immediate prognostic significance of complete atrioventricular block in acute myocardial infarction.

To discern the relative prognostic role of complete atrioventricular block (CAVB) in patients with acute myocardial infarction (AMI), 908 consecutive patients with AMI were studied over a 7-year period. Of the 559 patients with anterior wall AMI, 13 (2.3%) demonstrated CAVB, of whom 10 (76.9%) died in the hospital (vs 10.4% in those without CAVB) (p less than 0.001). In 349 patients with inferior wall AMI, 30 (8.6%) developed CAVB, of whom 6 (20%) died (vs 6.3% in those without CAVB) (p less than 0.01). In anterior wall AMI, all 5 patients with narrow QRS complexes (vs 8/11 with wide QRS complexes) (p = NS) died; in inferior wall AMI, 4/25 with narrow QRS complexes (vs 2/5 with wide QRS complexes) (p = NS) died. The mortality rate of patients with an escape frequency of less than or equal to 50/min did not differ significantly from that of patients with greater than 50/min regardless of the site of infarction or whether a pacemaker was used. In anterior wall AMI, the mortality rate of paced patients was 70% (7/10) compared to 100% (3/3) of non-paced patients (p = NS). In inferior wall AMI, the mortality rate of paced (5/25) and non-paced (1/5) patients was both 20%. Thus, none of the clinical parameters such as escape rhythm, the width of escape QRS complexes and pacemaker therapy discriminated the survivors from the deaths. In anterior wall AMI, episodes of cardiac standstill or bradycardia were of short duration, and pacemaker therapy was only one of the therapies applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Early diagnosis of acute myocardial infarction by myoglobin latex agglutination test.

Early elevation of the serum myoglobin level in acute myocardial infarction (AMI) has been noted for years. In this study, 39 patients admitted to the Coronary Care Unit with acute chest pain within 72 hours (mean 12 +/- 15 hours) or electrocardiographic changes suspected of acute myocardial infarction had a serum myoglobin latex agglutination test to evaluate its diagnostic accuracy in acute myocardial infarction. Of these 39 patients, 24 had documented acute myocardial infarction as their final diagnosis. By the time of admission, 18 of the 24 cases with infarction had positive myoglobin tests (sensitivity 75%). Of those 15 cases without myocardial infarction, 13 had negative myoglobin tests (specificity 87%). If only those 17 cases admitted within 5 hours of the onset of chest pain were analyzed, the serum myoglobin test became positive in 8 of 10 cases with documented AMI but the 2 cases with negative results turned positive 2 hours later (sensitivity 80% to 100%). Due to the fact that myoglobin tests were negative in all other 7 cases without infarction, the specificity was 7/7 (100%). In contrast, the creatine phosphokinase isoenzyme study was positive only in 3 of these 10 patients with documented AMI in the first blood sample taken during admission. In conclusion, the serum myoglobin latex agglutination test is a quick and reliable method that helps in the early diagnosis of acute myocardial infarction.

Adult↗
PubMed1988

[Evaluation of the apical seal produced by a hybrid root canal filling method, combining lateral condensation and thermomechanical compaction].

The present study measured apical leakage to a dye in roots filled by a hybrid root canal filling method, combining lateral condensation and thermomechanical compaction. The canals of 52 extracted human maxillary anterior teeth were endodontically prepared and divided into 3 groups. Lateral condensation was used in one group. The roots of the second one were filled using thermomechanical compaction. The roots of the third group were filled using hybrid method. After immersion in Procion Brilliant Green, the roots were cleared for measuring the depth of penetration of the dye under stereomicroscope. The roots filled with the hybrid method leaked less than the lateral condensation group, yet the difference was not significant (P greater than 0.05). The roots filled with both hybrid method and lateral condensation leaked significantly less (p less than 0.05) than the thermomechanical compaction group.

Dental Leakage↗
PubMed1987

Relationship between reestablishment of sarcolemma-glycocalyx ultrastructures and restoration of transmembrane potentials in cultured rat heart cells.

Simultaneous studies on sarcolemma-glycocalyx ultrastructures and electrophysiological properties of the trypsin-released rat heart cells were carried out in order to define the relationship between sarcolemmal membrane repair and transmembrane potential recovery in the long-term cultured heart cells. Based on electron microscopic observations of the trypsinized heart cells maintained in the long-term culture, serial alterations of sarcolemma-glycocalyx complex could be divided into three successive stages. A defective stage of the sarcolemma-glycocalyx complex was present in the cultured cells between day 3 and day 6 of incubation. A repaired stage of the sarcolemma-glycocalyx complex was observed in the cells from day 7 to day 9 of incubation. A well-organized stage of the sarcolemma-glycocalyx complex was seen in the cells after ten days of incubation. Sequential measurements of electrophysiological parameters of the cultured heart cells showed a diphasic evolution of maximum diastolic potential and action potential amplitude, with an initial decrease from day 3 to day 9 of incubation and a later return to normal range after ten days of incubation. There seemed a good correlation between electrophysiological properties and sarcolemma-glycocalyx ultrastructures. Thus, we conclude that restoration of the electrophysiological properties of the cultured cells is closely related to the reorganization of the defective sarcolemmal membrane.

Action Potentials↗
PubMed1986

Importance of adequate gas-mixing in contrast echocardiography.

Microbubble formation has been accepted as the mechanism producing contrast echoes. Comparisons of the contrast effects of various agents have been studied extensively, but the importance of gas-mixing has been less appreciated. To test the hypothesis that good gas-mixing, by facilitating microbubble formation, would enhance contrast effect, this study compared the contrast echocardiograms of ten adult patients before and after mixing carbon dioxide with various contrast agents. Contrast agents tested included a 5 percent glucose in water, vitamin B complex, vitamin C, and Cardiogreen solutions. First, we recorded echocardiograms by injecting each diluted contrast solution alone, then repeated the examinations using 10 ml of each diluted solution with 1 ml of carbon dioxide (CO2), mixed by means of a four-way stopcock. Satisfactory or excellent results were obtained in seven of ten, ten of ten, ten of ten, and ten of ten tests, respectively, after thorough gas-mixing, vs one of ten, seven of ten, eight of ten, and six of ten, respectively, before gas-mixing. We conclude that the addition of sufficient amounts of gas, followed by thorough mixing, is of great importance in contrast echocardiography. Consistently good results can be achieved with vitamin C, vitamin B or Cardiogreen solutions by this simple and safe method.

Adolescent↗