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Biomedical subjects

M H Hwang

Publications and source records attributed to M H Hwang.

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

Initial clinical evaluation of a wheelchair ergometer for diagnostic exercise testing: a technical note.

The purpose of this initial study was to evaluate a new wheelchair ergometer (WCE) and exercise test protocol for the detection of coronary artery disease in men with lower limb disabilities. Forty-nine patients (63 +/- 9 yr) completed WCE tests without complications. Peak heart rate was 84 +/- 15% (mean +/- SD) of age-predicted maximum and peak double product was 223 +/- 62 x 10(2). The specified target heart rate (> or = 80% age-predicted maximal) or a positive result was achieved in 76% of tests. Fourteen tests were rated positive, 21 as negative and 14 as nondiagnostic for exercise-induced ischemia. In 18 patients who underwent coronary angiography, the predictive value was 100% (10/10) for a positive, and 50% (2/4) for a negative WCE test result. These results suggest that WCE is a viable initial diagnostic option for some persons who cannot adequately perform treadmill or cycle ergometry exercise.

Adult↗
PubMed1994

Pain on injection of propofol.

A controlled randomized double-blinded clinical study was undertaken to evaluate and compare the efficacy of three methods of preventing pain during injection of propofol on induction of anesthesia. Patients were randomly allocated to six groups: saline pretreatment, followed by induction with propofol at room temperature plus saline; lidocaine pretreatment, followed by induction with propofol at room temperature plus saline; saline pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus saline; lidocaine pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus saline; saline pretreatment, followed by induction with propofol at room temperature plus lidocaine 40 mg; saline pretreatment, followed by induction with propofol at a temperature of 4 degrees C plus lidocaine 40 mg. Pretreatment with lidocaine reduced the incidence of pain and discomfort significantly compared with unpretreated groups. Groups which received propofol mixed with lidocaine also showed a significant reduced incidence of pain. induction with cold 4 degrees C propofol showed no significant difference in reduction of injection pain.

Adult↗
PubMed1994

Gastroduodenal intussusception due to Peutz-Jeghers syndrome. A case report.

An 18-year-old Chinese male was admitted to our hospital with recurrent abdominal pain, abdominal distension and intermittent non-bilious vomiting of about 2 months standing. A mildly tender mass measuring about 6 x 7 cm was present in the right upper quadrant area, and an abdominal computed tomography scan with enhancement showed a clearly encapsulated mass occupying the right side of the upper intra-abdominal area. Endoscopy revealed two huge cauliflower-like polyps and one small polyp in the stomach, and the biopsy specimens showed hyperplastic polyps. Moreover, multiple pigmentation of the buccal mucosa was also noted. The intra-abdominal mass was found to be a gastroduodenal intussusception following laparotomy. Gastroduodenal intussusception occurring secondarily to Peutz-Jegher syndrome, is a rarely documented condition. Only one case has been reported in Japan during the previous years. We report on another case, and review the literature.

Adolescent↗
PubMed1994

Comparison of the causes of late death following aortic and mitral valve replacement. VA Co-operative Study on Valvular Heart Disease.

This report examines and compares the causes of late non-surgical death in 146 of 690 (21%) patients undergoing isolated aortic valve replacement (AVR) and in 79 of 273 (29%) patients undergoing mitral valve replacement (MVR) over a five year follow up period. The distribution of valve related, cardiac but not valve-related and non-cardiac deaths was 43%, 23% and 34% respectively for AVR and 65%, 29% and 6% respectively for MVR; the difference between these distributions was statistically significant. The specific causes of valve related deaths included bleeding (11% vs. 5% for MVR vs. AVR), systemic embolization (6% vs. 4% for MVR vs. AVR), endocarditis (14% vs. 8% for MVR vs. AVR), valve regurgitation (8% vs. 5% for MVR vs. AVR) and valve obstruction (3% vs. 5% for MVR vs. AVR). Sudden death (less than one hour from the onset of acute symptoms) accounted for 23% of deaths for MVR and 16% for AVR. The deaths due to congestive heart failure with normal prosthetic valve function were 13% and 8% for MVR and AVR respectively. Non-cardiac causes accounted for only 6% of MVR deaths but 34% of AVR deaths (p < 0.001). There was no significant difference in the late mortality between mechanical and bioprosthetic valves in the aortic position (24% vs. 22%), but the cumulative rate of late deaths was higher in patients with the Björk-Shiley than with the Hancock valve in the mitral position (41% vs. 25%, p < 0.02). In conclusion, about one quarter of patients surviving either aortic or mitral valve replacement died within five years.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Regional changes in blood flow, extracellular potassium and conduction during myocardial ischemia and reperfusion.

OBJECTIVES: We postulated that ventricular arrhythmias may arise from the heterogeneous washout of ischemic metabolites. Our objective was to investigate the distribution of extracellular potassium concentration ([K+]o) during myocardial ischemia and reperfusion and to correlate this distribution with regional differences in myocardial blood flow. BACKGROUND: Our previous study showed that reperfusion after a brief period of ischemia resulted in heterogeneous reflow of the ischemic myocardium. METHODS: The changes in regional myocardial blood flow, midmyocardial [K+]o and electrogram duration were quantitated in 14 dogs undergoing 20 min of left anterior descending coronary artery occlusion and 1 min of reperfusion. Regional myocardial blood flow was measured by using 15-microns radioactive microspheres in 1- to 1.5-g full thickness myocardial samples. The [K+]o was measured with intramyocardial K(+)-sensitive electrodes. RESULTS: During coronary occlusion, the ischemic zone exhibited a reduction in regional blood flow to 0.13 +/- 0.06 ml/g per min and increases in [K+]o to 9.3 +/- 2.6 mmol/liter and electrogram duration to 131.8 +/- 38.6% of control. Heterogeneous reduction in regional blood flow at various sites in the ischemic zone had fair correlations with variable increases in [K+]o (r = -0.70) and electrogram duration (r = -0.75). During min 1 of reperfusion, regional blood flow ranged from two to more than seven times baseline, resulting in a disorganized spatial distribution of perfusion with islands of high and low blood flows. Associated with the heterogeneous early reperfusion regional myocardial blood flow, [K+]o and electrogram duration changed at different rates toward normal. Whereas correlation between regional blood flow and [K+]o or standardized electrogram duration was fair during ischemia, this correlation was poor during early reperfusion. CONCLUSIONS: Spatial heterogeneity in regional myocardial blood flow during myocardial ischemia and early reperfusion is associated with heterogeneity in [K+]o and electrophysiologic characteristics, which in turn may play an important role in the genesis of arrhythmias arising from the ischemic and reperfused myocardium.

Animals↗
PubMed1993

Percutaneous choledochoscopic biliary tract stone removal: experience in 645 consecutive patients.

Our experience in non-operative retrieval of biliary tract stones through PTCS (percutaneous transhepatic cholangioscopy, n = 103) and POC (post-operative choledochoscopy, n = 542) plus the use of Dormia basket and EHL (electrohydraulic lithotripsy) is presented. The results of transhepatic and T-tube routes are compared, with emphasis on the technical difficulties encountered. The success rates were 96% and 97% in POC and PTCS, respectively. No mortality was related to these procedures. Intrahepatic duct angulation and stricture were the factors most often responsible for failure. Postoperative choledochoscopic stone removal is safe and the method of choice for retained biliary tract calculi, while PTCS is highly indicated for those high-risk patients with or without previous biliary surgery. POC and PTCS have, therefore, their own indications and differ in their clinical applications.

Adult↗
PubMed1993

Percutaneous transcystic cholangioscopy for combined treatment of gallbladder and bile duct stones.

A procedure for percutaneous transcystic cholangioscopy requiring only one percutaneous transhepatic fistulous tract to remove stones located in both the gallbladder and bile ducts is described. The procedure begins with percutaneous transhepatic drainage of the gallbladder or bile duct. Stones in the gallbladder and bile duct can be removed under direct vision on transhepatic cholangioscopy. Larger stones can be fragmented by electrohydraulic lithotripsy before removal. In a preliminary trial the procedure proved to be a feasible method for treatment of 13 patients with both gallbladder and bile duct stones as well as septic cholangitis who either refused operation or were considered poor candidates for surgery. On long-term follow-up (mean period 28 months) stone recurrence was observed in three patients.

Aged↗
PubMed1993

The role of ERCP and therapeutic biliary endoscopy in laparoscopic cholecystectomy.

The widespread use of laparoscopic cholecystectomy for the treatment of symptomatic gallstones has been associated with an increased use of diagnostic and therapeutic biliary endoscopy to treat common bile duct stones and postoperative complications. In 250 patients with successful laparoscopic cholecystectomy, 35 were selected for preoperative ERCP evaluation after fitting the criterion of clinical evidence with common bile duct stones (ultrasound and biochemical data). Stones were found in 16 of 35 patients (45.7%). Endoscopic sphincterotomy with stone removal was successfully carried out during the procedure. Laparoscopic cholecystectomy was performed 1 or 2 days after endoscopic sphincterotomy with good result. Only one patient without clinical evidence of common bile duct stones developed postoperative retained stone; he was successfully treated by endoscopic sphincterotomy. Three patients with postoperative bile leakage were successfully treated with endoscopic nasobiliary drainage. Diagnostic and therapeutic ERCP procedures should incorporate the newly developed method of laparoscopic cholecystectomy in order to provide a more safe and minimal invasive therapy.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1993

[The study of anatomic factors in difficult intubations].

Endotracheal intubation is a common procedure in anesthesia which can usually be accomplished easily. However if the attempt is unexpectedly difficult the patient may be seriously at risk. If all difficult airways can be predicted confidently in the pre-operative period, anesthesiologists can plan the safest and most effective way of managing tracheal intubation. The purpose of this study was to analyze not only the incidence, anatomic factors, immediate complications and management of difficult intubation cases but also the view obtained at laryngoscope which was graded according to the Cormack's and Lehane's description. Patients who received general anesthesia with endotracheal tube within 1 year's period from November 1, 1991 to October 31, 1992 in Show Chwan Memorial Hospital were collected. All difficult intubations were performed by senior anesthesiologists. 3925 patients were intubated, 92 cases were noted to have difficult intubations and their overall incidence were 2.3%. Among the 92 patients, those with 2 anatomic factors (41 patients, 44.6%) represented the majority for patients with difficult intubations. On the other hand, the four most common anatomic factors and their incidences in order of frequency included short neck (48.9%), protruding teeth (38.0%), receding mandible (27.2%) and limited opening mouth (26.1%). According to Cormack's and Lehane's laryngoscopic grading, the results were shown respectively as follow: 4 cases (4.4%) for grade 1;2 cases (2.2%) for grade 2;82 case (89%) for grade 3 and 4 cases (4.4%) for grade 4. We also found that tachycardia/hypertension (70.7%), bleeding (37.0%) and esophageal intubation (33.7%) were the three most frequent immediate complications during difficult intubations.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1993

Diagnostic and therapeutic interventions in post-laparoscopic cholecystectomy biliary complications.

Radiological imaging and therapeutic interventions were performed in eight patients with biliary complications following laparoscopic cholecystectomy. The diagnostic approach and the outcome of the therapeutic procedures were evaluated. Complications observed were bile leakage from the cystic duct stump (n = 2); erroneous identification of the cystic duct leading to common hepatic duct transection (n = 1) and hepatic duct ligation (n = 2); liver abscess (n = 1); and retained common duct stones (n = 2). Diagnostic ultrasonography is capable of detecting the presence of abnormal fluid collection and the diameter of the common duct with or without the presence of a stone, although bile leaks and retained common duct stones can only be demonstrated by either endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. Once a bile leak had been confirmed, therapeutic endoscopic biliary stenting was successfully applied in one patient while the other received percutaneous transhepatic biliary drainage. Definitive diagnosis of retained common duct stone was established by endoscopic retrograde cholangiopancreatography, and immediate endoscopic sphincterotomy with stone extraction was performed. Follow-up radiological imaging was done to determine the effectiveness of the therapeutic procedures applied in each patient. All our patients improved clinically, and further surgical intervention was not needed.

Biliary Tract Diseases↗
PubMed1992

Therapeutic embolization of post-cholecystectomy hepatic artery aneurysm.

A "sandwich" technique employing steel coils and gelfoam embolization was applied in two cases of hepatic artery aneurysms. Immediate cessation of the bleeding was evident clinically and the post-embolization angiogram showed occlusion of the vascular lesion. Cholecystectomy is one of the most common abdominal operations and it is generally well tolerated, particularly in young and middle-aged patients. Morbidity rates of 5% to 32% and mortality rates of 0.4% to 2.5% have been reported, depending on such factors as age, underlying illness, etc. (1-4). The most frequent complications of cholecystectomy are wound infection, abscess, ductal injury or ligation, and bleeding. This paper describes two cases of hepatic pseudoaneurysm following iatrogenic damage during cholecystectomy which was treated with transarterial embolization.

Aneurysm↗
PubMed1992

Effects of intracoronary administration of contrast media on myocardial high-energy phosphate. A comparison of sodium meglumine diatrizoate and iohexol.

Myocardial ATP, ADP, and AMP were measured from cardiac biopsy in 11 dogs after intracoronary injection of 6 mL of sodium-meglumine diatrizoate (SMD), iohexol (IOH), or 0.9% sodium chloride (NaCl), and in three of the dogs at baseline before any injection. The ATP at baseline and after SMD, IOH, and 0.9% NaCl were 5.39 +/- 0.41, 3.72 +/- 0.70, 5.52 +/- 0.82, and 5.44 +/- 1.40 mumol/g wet weight, respectively. There were significant differences between SMD and IOH (P less than .02), and between SMD and 0.9% NaCl (P less than .05). The energy charge of SMD was 0.82 +/- 0.08, which differed from 0.89 +/- 0.02 for NaCl or 0.9 +/- 0.05 for baseline (P less than .05), but not from 0.85 +/- 0.04 for IOH. In conclusion, diatrizoate caused significant depletions in ATP stores in comparison with iohexol, but there was no significant difference with respect to energy charge. Nonionic contrast media would be preferable for coronary arteriography in patients whose high-energy stores might be depleted from severe ischemia.

Adenosine Diphosphate↗
PubMed1991

Effects of intracoronary administration of contrast media on coronary hemodynamics in a canine post ischemic reperfusion model.

Hemodynamic changes due to intracoronary injections of nonionic contrast medium Omnipaque-350 (OM), ionic dimer Hexabrix (HB), and ionic contrast medium Renografin-76 (R76) were compared at baseline and during reperfusion after a 30-minute left anterior descending coronary artery (LAD) occlusion. In 11 open chest, anesthetized, and atrially paced dogs, 4 ml of either OM, HB, R76, or 0.9% NaCl were injected into the carotid-LAD bypass system. Coronary blood flow (CBF) and coronary vascular resistance (CVR) were measured before, during and after the intracoronary injection. The maximal hyperemic change (in percentage) from the preinjection value of CBF and CVR were calculated. The results at baseline and during reperfusion for CBF were: 104 +/- 14% vs. 85 +/- 10% for OM (NS); 76 +/- 11% vs. 39 +/- 9% for R76 (p less than 0.05); 57 +/- 8% vs. 33 +/- 5% for HB (P less than 0.05); and 30 +/- 7% vs. 9 +/- 4% for 0.9% NaCl (p less than 0.05). Consequently, the hyperemic changes of CVR at baseline and during reperfusion were: -49 +/- 3 vs. -42 +/- 4% for OM (NS); -44 +/- 3% vs. -24 +/- 6% for R76 (p less than 0.01); -36 +/- 3% vs. -24 +/- 4% for HB (p less than 0.05); and -18 +/- 4% vs. -7 +/- 3% for 0.9% NaCl (p less than 0.05). Thus, ischemia and reperfusion significantly dampened the coronary hemodynamic and vascular response to R76, HB, and 0.9% NaCl but not to OM. The preserved coronary vascular reserve with high flow in this canine post-ischemic reperfusion model may explain the advantage of nonionic over ionic contrast media used in emergency coronary angiography following thrombolysis.

Animals↗
PubMed1991

A semiinvasive method for articular Colles' fractures.

An external fixation device that allows limited motion of the wrist joint without disruption of the anatomic alignment was used for the articular Colles' fractures in this study. From July 1985 to April 1989 during a 45-month period, 87 patients with 90 articular Colles' fractures (three cases with bilateral involvement) were treated with a modified dynamic external skeletal device after a closed reduction in full supination of the forearm. Excellent anatomic reduction near 91% of the sound wrist as well as satisfactory functional results around 90.5% of the sound wrist were gained during the 24-month follow-up period. Forearm muscles exert compression forces on distal radial metaphyseal fractures throughout the healing period. Any procedure or device that cannot provide constant counterforce to the action of forearm muscles during fracture healing will result in the loss of anatomic reduction. Adequate distraction counter-force was provided by an external fixation device that was superior to other conventional methods because of its simple application, low rate of complications, and excellent anatomic and functional results.

Adolescent↗
PubMed1990

Effect of heparin in nonionic contrast media on blood coagulation and its dose response curve.

To investigate the local effect of heparin on blood clot formation and partial thromboplastin time (PTT), blood was withdrawn into the catheters filled with iopamidol and heparin at 0, 1, 2, 3, 5, and 10 U per ml concentrations as debubbling. After 30 min incubation, blood clotting was observed in all 8 experiments with heparin concentrations of 0 and 1 U per ml; in 3 of 8 with 2 U per ml; and in none with greater than or equal to 3 U per ml. PTT of blood and contrast mixture in catheters increased significantly when heparin concentrations were increased from 2 to 3 U per ml and reached a level of greater than 110 sec at 5 or more U per ml. Thus, the addition of heparin to nonionic contrast media at concentrations of 5 U per ml may be an easy measure with which to prevent blood clotting and reduce thromboembolic complications during coronary arteriography.

Blood Coagulation↗
PubMed1990

Progression of native coronary artery disease at 10 years: insights from a randomized study of medical versus surgical therapy for angina.

Repeat coronary angiography was performed in 42 patients 10 years after randomization to medical (n = 21) or surgical (n = 21) therapy for chronic angina. The native coronary arteries were classified into 15 angiographic segments and 3 arterial trunks for analysis of progression of coronary artery disease. The incidence rate of disease progression in coronary segments was 24% and 28% in medically and surgically treated patients, respectively (p = NS). Grafted segments showed a 38% rate of disease progression, which was higher than the 18% rate of for nongrafted segments (p less than 0.001) and the overall rate of 24% for medically treated patients (p less than 0.01). Similarly, 29 (94%) of 31 grafted arteries exhibited disease progression compared with 19 (59%) of 32 nongrafted arteries (p less than 0.01) and 42 (67%) of 63 arteries in medically treated patients (p less than 0.01). In grafted vessels, disease progression occurred more often in arteries proximal (84%) to the anastomosis than in arteries distal (16%) to graft insertion (p less than 0.001). Progression occurred in 46% of proximal segments compared with 23% of distal segments (p less than 0.02). Progression was seen in 23 (55%) of 43 segments with an occluded graft compared with 30 (31%) of 96 segments with a patent graft (p less than 0.02). Ten years after randomization, medically and surgically treated patients showed a comparable rate of disease progression in coronary segments. However, surgical therapy appeared to significantly accelerate atherosclerotic progression in the grafted vessels, especially in the proximal portions. Occluded grafts also correlated with an adverse effect on disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1990

Cardiac hemangioma.

Hemangiomas are uncommon primary tumors of the heart. Most of them are found incidentally at autopsy, during clinical evaluation, or cardiac surgery. Occasionally, a protean clinical picture is manifested, including valvular disorder, arrhythmias, obstruction of coronary artery and other significant vasculature, pericardial effusion, and embolic phenomena. Catheterization, angiography, and echocardiography all play some important role in the antemortem diagnosis of this cardiac tumor. The treatment of choice is simple complete excision. In this review, we add our experience with cardiac hemangiomas: one incidentally discovered at autopsy and another found during coronary artery bypass surgery.

Adolescent↗