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Biomedical subjects

C L Hwang

Publications and source records attributed to C L Hwang.

At least 19 recordsLinked to original sources
PubMed1995

Regression of left ventricular aneurysm after delayed percutaneous transluminal coronary angioplasty (PTCA) in patients with acute myocardial infarction.

Two weeks after acute myocardial infarction (AMI), 23 patients received delayed percutaneous transluminal coronary angioplasty (PTCA) and 14 consecutive randomized selected patients received conservative treatment as a control group. Follow up intravenous and/or intraventricular left cine-ventriculography, as well as radionuclide ejection fraction were performed 6-24 months (mean 11.2 months) after the acute phase. The results showed no significant statistical differences between the two groups for age, sex, Killip class, left ventricular end-diastolic pressure, and medication. The PTCA group showed a significant increase in radionuclide left ventricular ejection fraction, when compared to the control group (20.4 +/- 0.3 vs. 2.05 +/- 1.2; P < 0.05), as well as in the cine-global ejection fraction (32.1 +/- 0.4 vs. 3.44 +/- 1.1; P < 0.05). The dyskinetic area and volume were found also to have greater reduction in the PTCA group than in the control group (-84.7 +/- 1.2 vs. -10.5 +/- 1.1 and -86.1 +/- 1.1 vs. -15.4 +/- 0.9; P < 0.05). There were no significant changes in diastolic or systolic circumferences for both group. In conclusion, delayed PTCA after AMI can reduce the left ventricular dyskinetic area, and improve cine-global ejection fraction. Intravenous first pass left ventriculography is a safe, simple, and reproducible method for evaluating left ventricular remodeling after acute myocardial infarction.

Aged↗
PubMed1995

Use of a low profile Doppler angioplasty guidewire to evaluate the effect of percutaneous coronary angioplasty on coronary artery flow velocity.

BACKGROUND: The intracoronary Doppler flow velocity measurement is widely used. The Doppler flow catheter, used in many studies, still cannot always measure distal portions of coronary artery stenosis. However, three years ago, a low profile Doppler angioplasty guide wire (0.018-inch) was started by apply for measurement of changes in proximal and distal flow velocity during coronary angioplasty. METHODS: Blood flow velocity and diastolic/systolic velocity ratio (DSVR) on both proximal and distal portions of the coronary artery were measured with a low profile Doppler angioplasty guide wire in 13 patients with stenosis of the left anterior descending artery (LAD) during coronary angioplasty. RESULTS: Non-significant improvement in maximal peak velocity was noted in the distal portion of the coronary artery immediately after angioplasty (before, 36 +/- 12 cm/s; after, 41 +/- 12 cm/s; p > 0.05); but significant improvement was found after removal of the balloon (from 41 +/- 12 cm/s to 49.5 +/- 15 cm/s, p < 0.01). Increases in proximal maximal peak velocity after angioplasty were less remarkable (before, 38.5 +/- 15 cm/s; after, 45 +/- 13 cm/s; p > 0.05), and there was a significant increase of DSVR on the distal portion of the left anterior descending artery after angioplasty (before, 2.18 +/- 0.51; after, 2.98 +/- 0.44; p < 0.05). However, there was no significant increase of DSVR on the proximal portion of LAD (before, 2.19 +/- 0.16; after, 2.44 +/- 0.1; p > 0.05). The coronary flow reserve ratio showed no significant increase on the distal portion of the LAD (before, 1.03 +/- 0.3; after, 1.02 +/- 0.3) and proximal portion of LAD (before, 1.05 +/- 0.2; after, 1.03 +/- 0.3). CONCLUSIONS: Increase in peak velocity and DSVR of the distal portion of the coronary artery after angioplasty was more significant after removal of the balloon catheter than as if it were assessed immediately, without removing the balloon catheter. No significant increase in flow velocity of the proximal portion of the coronary artery after angioplasty was observed. No significant increase of the coronary flow reserve of the distal and proximal portion of the coronary artery occurred after successful angioplasty.

Adult↗
PubMed1994

U-50,488 blocks the development of morphine tolerance and dependence at a very low dose in guinea pigs.

U-50,488, (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzeneacetamide hydrochloride), is a selective kappa-opioid receptor agonist. In this study, we found that U-50,488 antagonized morphine-induced antinociception in morphine-naive guinea pigs at doses which did not have any antinociceptive effect by themselves (0.01-3 mg/kg). On the other hand, U-50,488 (3 mg/kg) partially restored morphine-induced antinociception in morphine-tolerant guinea pigs (8 mg/kg/day i.p. morphine HCl for 6 days). Furthermore, the development of tolerance to morphine antinociception was completely blocked by coadministration of U-50,488 at a very low dose (0.003 mg/kg i.p.) which neither exerted an antinociceptive effect by itself nor affected the antinociception induced by 8 mg/kg of morphine HCl. The withdrawal signs induced by 8 mg/kg (i.p.) naloxone HCl on the 7th day were also depressed by coadministration of 0.003 mg/kg U-50,488 with morphine HCl (8 mg/kg i.p.) every day for 7 days. These effects of U-50,488 could be applied to humans to prevent morphine tolerance and dependence.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1994

Comparison of the effects of nifedipine and nitroglycerin on coronary blood flow using intracoronary Doppler catheter.

Different effects of nifedipine and nitroglycerin on large coronary arteries measured by the Xenon washout method are well documented in early reports, but results of direct measurements of the flow velocity of the large vessels were inconsistent. The goal of this investigation was to compare the effects of nifedipine and nitroglycerin on coronary blood flow using an intracoronary Doppler catheter. Fourteen patients with normal coronary arteries (group 1) and eight (group 2) with coronary artery diseases (more than 75% concentric stenosis over the left anterior descending artery in the middle portion) were presented on diagnostic procedure for evaluation of chest pain or abnormal exercise tests after written informed consents. We compared the effects of nitroglycerin (0.6 mg) and nifedipine (10 mg) given sublingually on coronary blood flow velocity using a Doppler coronary catheter. The results indicated that the maximal increase in large coronary arterial diameter induced by nifedipine was similar to that induced by nitroglycerin. Nifedipine increased diastolic and systolic velocity area indices (DVAI and SVAI), and reduced diastolic and systolic coronary vascular resistance (DCVRI and SCVRI). In contrast, nitroglycerin reduced DVAI and SVAI and minimally increased DCVRI and decreased SCVRI in group 2 patients. The increased heart rate and decreased blood pressure induced by both drugs were similar. The differences in the rate-pressure product between the two drugs were not significant. Nifedipine increased flow velocity and decreased coronary vascular resistance, but nitroglycerin achieved the opposite effect, especially in patients with coronary artery disease.

Aged↗
PubMed1994

Percutaneous excimer laser coronary angioplasty: animal models and the first human experience in Taiwan.

BACKGROUND: Clinical studies with excimer laser coronary angioplasty (ELCA) have been published in USA and Germany for lesions too difficult for use of routine balloon angioplasty. The purpose of the study was to evaluate the safety and short-term effects of excimer laser radiation applied to canine coronary angioplasty, and to report the first experience with percutaneous coronary excimer laser angioplasty and adjunctive percutaneous transluminal coronary angioplasty (PTCA) in a human subject on Taiwan. METHODS: Twelve canine subjects were studied. An excimer laser (Technolas Inc. Max-10), 20 Hz, 35 mJ/mm2, and 60 ns pulse was used. RESULTS: There were no perforations, with minimal dissection on the arterial intimal layer after using the bare-tip (crude single fiber-optic) fiber laser. The human subject showed partially successful recanalization after ELCA, with no residual stenosis after adjunctive PTCA for an occluded left anterior descending (LAD) artery (proximal lesion). A 0.014-in guide wire was used. There were no complications except for premature ventricular contractions during the procedure. CONCLUSIONS: The percutaneous excimer laser angioplasty is an effective and safe tool for treating coronary artery disease.

Angioplasty, Balloon, Coronary↗
PubMed1993

Proposed healing and consolidation mechanisms of rock salt revealed by ESEM.

The grain boundary healing behavior of crushed rock salt was mainly studied by employing the environmental scanning electron microscope (ESEM) to study the consolidation mechanism of rock salt backfill. Dedicated miniature round rock salt specimens were prepared for observation of the water trapping effect by using a cold stage in the ESEM to reach saturation conditions. Comparable high pressure pellets were prepared for measuring the crystal growth. Consolidation tests using materials made at different pressures and containing different moisture levels were conducted in order to construct the proposed mechanism. Direct observation of specimens in the ESEM resulted in viewing water trapped on the surface and the formation of a water meniscus between two particles. The concentration of brine at the grain boundary was observed as contributing to the amount of recrystallization. From aforementioned observations, a schematic drawing of the dissolution and recrystallization process may be redrawn. The amount of water therefore has a great effect on the consolidation of rock salt and is possibly due to the sliding, rotation, or crushing of the contact zone of the granular material. From such a study, tentative healing and consolidation mechanisms can be deduced.

Microscopy, Electron, Scanning↗
PubMed1993

99mTc-sestamibi can improve the inferior attenuation of TL-201 myocardial spect imaging.

Tl-201 myocardial scintigraphy (Tl study) tends to be attenuated by soft tissues (such as the diaphragm) due to its low energy emission. 99mTc-sestamibi (2-methoxy isobutyl isonitrile) is a relatively new agent with a higher energy emission and this characteristic accounts for the higher quality of 99mTc-sestamibi images. The purpose of this study is to evaluate the ability of 99mTc-sestamibi in alleviating the inferior attenuation of Tl studies. 99mTc-sestamibi SPECT myocardial scintigraphy was performed on 13 patients with inferior wall perfusion defects as determined by Tl study (but with normal coronary artery as evidenced by cardiac catheterization). All patients underwent Tl SPECT study using a standard procedure. Same-day protocol (rest-stress sequence) was used for 99mTc-sestamibi SPECT imaging. All images were analyzed by two independent observers. The results of our study reveal that 99mTc-sestamibi produced better images. The inferior wall perfusion defects in the T1 study were noted in one case only (1/13) in the 99mTc-sestamibi study. Our study suggests that 99mTc-sestamibi can remarkably reduce the inferior attenuation of Tl study.

Angina Pectoris↗
PubMed1992

Pericardiocentesis: a 20 patients study.

Emergency pericardiocentesis, guided by a two-dimensional echocardiography, was performed on twenty patients with symptomatic pericardial effusion of various types and causes. There were fourteen men and six women. The underlying causes were: primary lung cancer (6 cases), metastatic cardiac tumors (3 cases), tuberculosis (4 cases), complicated interventional procedures with cardiac chamber or vessel perforations (2 cases), dissecting aortic aneurysm (1 case), systemic lupus erythematous (1 case), idiopathic pericarditis (1 case), bacterial pericarditis (1 case), and myxedema heart disease (1 case). Seventeen cases were performed through the left xipho-sternal approach and 3 cases through the apical approach. None of the patients died as a result of these procedures. A two-dimensional echocardiogram is useful in diagnosing cardiac tamponade as well as in guiding pericardiocentesis, and obtaines highly positive results (20/20). The positive rate of pericardial fluid cytology for malignant cells was 89% (8/9), however, pericardial fluid cultures or direct smear for tuberculosis were negative (0/4). In cancer patients, the mean survival time following pericardiocentesis was 4.2 months (range, 1-7.8 months). We concluded that neoplastic involvement of the pericardium is the most frequent cause of symptomatic pericardial effusion. Pericardiocentesis assisted by a two-dimensional echocardiogram is safe and easy. In addition, pericarditis caused by TB is still significant and must be considered in every case in our nation.

Adult↗
PubMed1990

Suppression of hemodynamic change before extubation--lidocaine through modified endotracheal tube.

Twenty females, aged 31 to 49 years, scheduled for abdominal total hysterectomy were randomly divided into two groups in this study. An epidural catheter was placed at T11-12 before general anesthesia. All patients receive the combination of epidural anesthesia and general anesthesia for the operation and relief of pain postoperatively. The modified endotracheal tube we used is shown in Fig. 1. For patients in group I (Lidocaine group), 2 mL 4% lidocaine solution was injected through the catheter to desensitize the tracheal mucosa around the cuff after the surgeon had removed the uterus. In group II (Control group), no special management was made. All patients were not extubated until they were considered to be awake. Systolic blood pressure at three and one minute before extubation and pulse rate recorded at one minute before extubation showed in patients of group I were statistically smoother than those recorded in group II (p less than 0.01). All patients had gag reflex just after awake extubation.

Adult↗
PubMed1990

A new approach to suppress bucking before extubation--lidocaine through modified endotracheal tube.

The conventional endotracheal tube was modified with an epidural catheter adhered on the concave aspect of it. The opening of the catheter is at the proximal margin of the cuff. Local anesthetic can be injected into the trachea, then desensitize the tracheal mucosa nearby the cuff. Thirty-four female gynecological patients underwent abdominal total hysterectomy were studied and divided into three groups. In group 1, anesthesia was maintained without special management. In groups 2 and 3, 2 mL gentian violet stained 4% lidocaine solution was administered intratracheally by two different methods 60-120 minutes before the conclusion of the surgery. The peak cuff pressures generated by the awakening patients were 53.8 +/- 2.2 cm H2O (mean +/- SE) in group 1, 47.3 +/- 2.5 cmH2O (Group 2) and 36.4 +/- 1.6 cmH2O Group 3) respectively. Bucking before awakening was also evaluated clinically and showed 100%, 73% and 0% in each group. Intratracheal administration of lidocaine in dose of 2 mL 4% showed significant effect for the suppression of bucking during the recovery of general anesthesia in group 2 and 3 compared with the group 1. Lidocaine administered through the catheter of modified endotracheal tube also resulted in less increase in the peak cuff pressure and even no clinically observed bucking than direct administered through the endotracheal tube. Gag reflex was preserved in all patients and none had suffered from aspiration postoperatively.

Adult↗
PubMed1990

The application of pulse oximeter for supraclavicular brachial block.

The subclavian artery is the most important landmark of the supraclavicular brachial block. However, it is difficult to locate the artery by palpation in the patients with poor landmark. The present study was aimed to compare two localizing methods of the subclavian artery by a pulse oximeter or by palpation. One hundred patients were divided into three groups. Group A (Slim Group): 6 patients, Group B (Normal Weight Group): 75 and Group C (Obese Group): 19. All patients received both methods to locate the subclavian artery. The first method was by palpating the pulsation of the subclavian artery. The second was by observing the wave depression of the pulse oximeter while pressing supraclavicular area. It was found that the detection rate of the first method was 83.3% in Group A, 52.0% in Group B, 26.3% in Group C and 49.0% in overall patients. However, the detection rate of the second method was 100% in each group. It shows a significant difference between the two methods in Group B, Group C and all patients (P less than 0.001), but no difference in Group A (P = 0.68). There were 13 patients among the 100 patients undergoing surgery of the upper extremity. Seven of them whose pulsation was not clearly palpated but could be located exactly by pulse oximeter. Supraclavicular brachial block was still completed successfully in these 13 patients. No pneumothorax was found. Utilizing pulse oximeter in supraclavicular block provides a high detection rate of the pulsation of the subclavian artery and improves the reliability of the block, especially in the patients with poor landmark.

Adult↗
PubMed1990

Estimation of the length of nasopharyngeal airway in Chinese adults.

Nasopharyngeal airway should be placed to reach the tongue base without contact with the epiglottis. The correct length of the nasopharyngeal airway in Chinese adults was estimated in seventy-three surgical patients under general anesthesia (30 males and 43 females, aged 18-82 yr). Measurements were performed with a soft, uncuffed, ID 6.0 mm endotracheal tube (Portex) introduced through the nasopharyngeal passage. The proper tip placement of the tube was evaluated under direct laryngoscopy. The Nostril-epiglottis distance (N-E distance) is 15.31 +/- 1.09 cm (mean +/- SD) for all cases, 16.03 +/- 1.04 cm for male cases and 14.97 +/- 0.95 cm for female cases. There are correlation between the N-E distance and the height (p less than 0.001, r = 0.41), and between the N-E distance and the N-A distance (The distance from nose tip to mandibular angle) (p less than 0.004, r = 0.324). Linear regression analysis relating the N-E distance to the height and the N-E distance to the N-A distance were also statistically significant (p less than 0.001 and p less than 0.01, respectively).

Adolescent↗