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Biomedical subjects

K J Chung

Publications and source records attributed to K J Chung.

At least 19 recordsLinked to original sources
PubMed2000

Influential factors affecting prognosis of snakebite patients management: Kaohsiung Chang Gung Memorial Hospital experience.

BACKGROUND: The objective of this study was to determine the most influential factors affecting the prognosis of snakebite patients in Kaohsiung Chang Gung Memorial Hospital. METHODS: A thorough review of the medical records of poisonous snakebite from June 1986 to November 1999 was carried out in this retrospective study. RESULTS: Of the identified snakes in 39 bite victims, 70% of these cases were hemorrhagic type: Trimeresurus stejnegeri 20/27, T. mucrosquamatus 6/27, and Agkistrodon acutus 1/27; 28% were neurotoxic type: Naja naja atra 6/11 and Bungarus multicinctus 5/11; and 2% was mixed type: Vipera russelli formosensis 1/39. Three of four acute renal failure victims were bitten by T. mucrosquamatus. Two of the 5 victims bitten by B. multicinctus required endotracheal intubation to maintain their respiration. Five patients received skin grafting, 3 of whom were bitten by Naja naja atra. Most of our patients (55%) received only a single dose of antivenin, and 83% (29/35) of the antivenin was given within 6 hours after the bite; the antivenin infusion was finished in less than 2 hours in most cases (33/36). CONCLUSION: Bites from Trimeresurus stejnegeri are the most common poisonous snakebite recorded in our emergency department. T. mucrosquamatus is prominent in causing bleeding tendency and acute renal failure. Bungarus multicinctus is more prominent than Naja naja atra in causing acute respiratory failure. The dosage of antivenin used to treat patient bitten by cobra was less than that recommended by the poison control center, and the complication of skin necrosis requiring skin grafting was more severe than that of the other species.

Adolescent↗
PubMed1993

Cine magnetic resonance imaging and color Doppler flow mapping in infants and children with pulmonary artery bands.

Cine magnetic resonance imaging (MRI) and color Doppler flow mapping were performed in 12 infants and children (aged 3 to 35 months) after pulmonary artery banding to define the anatomy and physiology of the right ventricular outflow tract and evaluate the anatomy. MRI was performed using a 1.5 Tesla magnet in the sagittal, axial and oblique views with all patients studied in the 24 cm head coli following adequate sedation. High-resolution cine MRI was obtained in all patients and the narrowest flow diameter on cine MRI correlated well with the pressure gradient measured across the band in 11 patients at cardiac catheterization or surgery (r = -0.95). Signal loss was always seen distal to the band associated with turbulent flow as seen by color Doppler flow mapping. Signal loss in cine MRI was also seen proximal to the band. The length of this proximal signal void also correlated well with the pressure gradient measured across the band (r = 0.91) and was closely matched by the zone of proximal spatial acceleration defined by digital computer analysis of color Doppler flow map images (r = 0.89), which also demonstrated low grade variance associated with the laminar accelerating flow stream. The position of the band was accurately defined by cine MRI which identified inadequate pulmonary artery banding in 2 patients confirmed subsequently at cardiac catheterization and angiography. Cine MRI and color Doppler flow mapping when used together provide high-resolution detail about the right ventricular outflow tract and pulmonary artery band anatomy and function.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1993

Cine magnetic resonance imaging and color Doppler flow mapping displays of flow velocity, spatial acceleration, and jet formation: a comparative in vitro study.

To study the effects of flow acceleration and high-velocity jets on the display characteristics of cine magnetic resonance imaging compared with color Doppler flow mapping, a custom-designed in vitro flow model was developed. This model consisted of a funnel segment tapering to an orifice (0.78 cm2) that leads into a confined receiving chamber with a second, discrete orifice (0.78 cm2) at its distal end. Cine magnetic resonance images obtained at varying flow rates (1.5 to 27.2 L/min) demonstrated loss of signal intensity throughout the tapering zone of spatial acceleration and a small zone of more marked signal loss immediately proximal to the second orifice (always < 50% of the signal intensity within the tapering funnel zone) associated with more rapid spatial acceleration. A formed jet was imaged distal to the first orifice, and the turbulence area surrounding the laminar central jet core correlated well with flow rate (r = 0.98), as did the distance from the orifice to the subsequent onset of flow relaminarization (r = 0.96). A turbulent spray area was always seen distal to the second, discrete orifice. Comparative observations with color Doppler flow mapping and continuous wave Doppler demonstrated that signal intensity on cine magnetic resonance imaging is reduced by both spatial acceleration, and the high-velocity and turbulent jets associated with obstructive and regurgitant lesions. In vitro evaluation of cine magnetic resonance imaging allows comparative observations to be made about the flow characteristics of cine magnetic resonance imaging and color Doppler flow mapping and provides a more rational basis for the interpretation of cine magnetic resonance imaging in the clinical setting.

Blood Flow Velocity↗
PubMed1991

A single intravenous infusion of gamma globulin as compared with four infusions in the treatment of acute Kawasaki syndrome.

BACKGROUND: Treatment of acute Kawasaki syndrome with a four-day course of intravenous gamma globulin, together with aspirin, has been demonstrated to be safe and effective in preventing coronary-artery lesions and reducing systemic inflammation. We hypothesized that therapy with a single, very high dose of gamma globulin would be at least as effective as the standard regimen. METHODS: We conducted a multicenter, randomized, controlled trial involving 549 children with acute Kawasaki syndrome. The children were assigned to receive gamma globulin either as a single infusion of 2 g per kilogram of body weight over 10 hours or as daily infusions of 400 mg per kilogram for four consecutive days. Both treatment groups received aspirin (100 mg per kilogram per day through the 14th day of illness, then 3 to 5 mg per kilogram per day). RESULTS: The relative prevalence of coronary abnormalities, adjusted for age and sex, among patients treated with the four-day regimen, as compared with those treated with the single-infusion regimen, was 1.94 (95 percent confidence limits, 1.01 and 3.71) two weeks after enrollment and 1.84 (95 percent confidence limits, 0.89 and 3.82) seven weeks after enrollment. Children treated with the single-infusion regimen had lower mean temperatures while hospitalized (day 2, P less than 0.001; day 3, P = 0.004), as well as a shorter mean duration of fever (P = 0.028). Furthermore, in the single-infusion group the laboratory indexes of acute inflammation moved more rapidly toward normal, including the adjusted serum albumin level (P = 0.004), alpha 1-antitrypsin level (P = 0.007), and C-reactive protein level (P = 0.017). Lower IgG levels on day 4 were associated with a higher prevalence of coronary lesions (P = 0.005) and with a greater degree of systemic inflammation. The two groups had a similar incidence of adverse effects (including new or worsening congestive heart failure in nine children), which occurred in 2.7 percent of the children overall. All the adverse effects were transient. CONCLUSIONS: In children with acute Kawasaki disease, a single large dose of intravenous gamma globulin is more effective than the conventional regimen of four smaller daily doses and is equally safe.

Acute Disease↗
PubMed1989

Elucidation of the natural history of ventricular septal defects by serial Doppler color flow mapping studies.

Two-dimensional echocardiography has provided information to aid in the diagnosis and management of infants with ventricular septal defect, but its inability to resolve very small ventricular septal defects and problems with defining ventricular septal defect orifice size (because of overlying muscle or tricuspid tissue) have made it unsuitable as a standard for defining the natural history of ventricular septal defect. In this study, 114 serial two-dimensional Doppler color flow mapping studies were performed to define ventricular septal defect anatomy, location and color flow diameter as an indicator of shunt size in 66 patients (over a 40 month period). Twenty-five patients first studied at 6 months of age (mean age at most recent study 15.9 months) had congestive heart failure and 41 (mean age 45 months) did not. In the congestive heart failure group, there were 24 perimembranous and 1 muscular ventricular septal defect and aneurysm formation was present in 17. Mean (+/- SD) color flow diameter was 8.2 +/- 1.9 mm and color flow diameter/aortic root diameter ratio was 0.63. In the 30 patients who underwent cardiac catheterization, color flow diameter bore a close relation to angiographic diameter (r = 0.96) and pulmonary/systemic flow ratio (Qp/Qs) (r = 0.88). In the patients with congestive heart failure, 4 of the 25 ventricular septal defects, all with aneurysm present or positioned adjacent to the tricuspid valve, became smaller but none closed. Of the 41 patients without congestive heart failure, 21 had a perimembranous defect (15 with aneurysm), 18 had a muscular ventricular septal defect and 2 had a supracristal ventricular septal defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables.

The spatial distribution of simulated regurgitant jets imaged by Doppler color flow mapping was evaluated under constant flow and pulsatile flow conditions. Jets were simulated through latex tubings of 3.2, 4.8, 6.35 and 7.9 mm by varying flow rates from 137 to 1,260 cc/min. Color jet area was linearly related to flow rate at each orifice (r = 0.96, SEE = 3.4; r = 0.99, SEE = 1.6; r = 0.97, SEE = 2.3; r = 0.97, SEE = 3.2, respectively), but significantly higher flow rates were required to maintain the same maximal spatial distribution of the jet at the larger regurgitant orifices. Constant flow jets were also simulated through needle orifices of 0.2, 0.5 and 1 mm, with a known total volume (5 cc) injected at varying flow rates and with differing absolute volumes injected at the same flow rate (0.2, 1.0 and 2.0 cc/s, respectively). Again, maximal color jet area was linearly related to flow rate at each orifice (r = 0.97, SEE = 2.3; r = 0.97, SEE = 2.4; r = 0.92, SEE = 3.9, respectively), but was not related to the absolute volume of regurgitation. Color encoding of regurgitant jets on Doppler color flow maps was demonstrated to be highly dependent on velocity and, hence, driving pressure, such that color encoding was obtained from a constant flow jet injected at a velocity of 4 m/s through an orifice of 0.04 mm diameter with flow rates as low as 0.008 cc/s. Mitral regurgitant jets were also simulated in a physiologic in vitro pulsatile flow model through three prosthetic valves with known regurgitant orifice sizes (0.2, 0.6 and 2.0 mm2). For each regurgitant orifice size, color jet area at each was linearly related to a regurgitant pressure drop (r = 0.98, SEE = 0.15; r = 0.97, SEE = 0.20; r = 0.97, SEE = 0.23, respectively), regurgitant stroke volume (r = 0.77, SEE = 0.55; r = 0.94, SEE = 0.30; r = 0.91, SEE = 0.41, respectively) and peak regurgitant flow rate (r = 0.98, SEE = 0.16; r = 0.97, SEE = 0.21; r = 0.93, SEE = 0.37, respectively), but the spatial distribution of the regurgitant jets was most highly dependent on the regurgitant pressure drop. Jet kinetic energy calculated from the summation of the individual pixel intensities integrated over the jet area was closely related to driving pressure (r = 0.84), but integration of the power mode area times pixel intensities provided the best estimation of regurgitant stroke volume (r = 0.80).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Factors influencing the structure and shape of stenotic and regurgitant jets: an in vitro investigation using Doppler color flow mapping and optical flow visualization.

To evaluate factors influencing the structure and shape of stenotic and regurgitant jets, Doppler color flow mapping and optical flow visualization studies were performed with use of a syringe model with a constant rate of ejection to simulate jets of valvular regurgitation and a pulsatile flow model of the right heart chambers to simulate jets of mild, moderate and severe valvular pulmonary stenosis. Ink-(0 to 40%) glycerol-water jets (viscosity 1 to 3.5 centiPoise) were produced by injecting the fluid at a constant rate into a 10 gallon rectangular reservoir of the same still fluid through 1.4 and 3.4 mm needles. The Doppler color flow scanners imaged the laminar jet length within 3 mm of actual jet length (2 to 6 cm) and the jet width within 2 to 3 mm of the actual jet width. Jet flows with Reynolds numbers ranging from 230 to 1,200 injected into still fluid yielded jet length/width ratios that decreased with increasing Reynolds numbers and leveled off to a length/width ratio of 5-6:1 at a Reynolds number near 600. When the fluid reservoir was swirled to better mimic the effect of flow entering the same cardiac chamber from a second source, the jets showed diminution of the jet length/width ratio and a clearly defined zone of turbulence. Studies of the pulsatile flow model were performed at cardiac outputs of 1 to 6 liters/min for the normal and each stenotic valve. Mild stenosis had an orifice area of 2.8 cm2, moderate stenosis an area of 1.0 cm2 and severe stenosis an area of 0.5 cm2. Laminar jet length represented the length of the total jet, which had a symmetric width and was measured from the valve opening to a region where the jet exhibited a spray effect. Laminar jet lengths (0.2 to 1.1 cm) were imaged by Doppler color flow mapping and optical visualization only in the moderate and severely stenotic valves and only at flows less than or equal to 3 liters/min (mean Reynolds numbers less than or equal to 3,470). Beyond this flow rate the jets exhibited a spray effect. Laminar jet length/width ratio approached unity with an increased amount of valvular stenosis and higher flow volumes (cardiac output). Proximal aliasing was present in each valve studied. the length of aliasing (0 to 3.2 cm) proximal to the valve was longer with increased flow rates and increased amounts of stenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Flow Velocity↗
PubMed1989

Cardiac function, substrate utilization, and myocardial energy metabolism studied with 31-P NMR spectroscopy during acute hypoglycemia and hyperketonemia.

Whether severe hypoglycemia alone or in combination with hyperketonemia might cause deterioration of cardiac function has been controversial. Therefore, the influence of acute hypoglycemia (mean 33 mg/dL) with and without hyperketonemia (mean 1.3 and 3.3 mM) on cardiac function, substrate utilization, and myocardial high energy phosphate levels was studied in 10 mongrel dogs. After 45 min of hypoglycemia, mean aortic pressure, total peripheral resistance, and myocardial oxygen consumption had increased significantly, but other hemodynamic parameters and regional myocardial function had not changed. Additional infusion of 3-hydroxybutyrate did not affect hemodynamic variables significantly. During both metabolic interventions in vivo phosphorus-31 nuclear magnetic resonance spectroscopy showed stable levels of myocardial phosphocreatinine, ATP, as well as the phosphocreatinine/ATP (3.0-3.2) ratio. Biochemical measurements revealed that hyperketonemia led to significant alterations in arterial concentrations and arteriocoronary venous differences of selected citric acid cycle intermediates, thus confirming previous reports which suggested a blockade of the 2-oxoglutarate-dehydrogenase reaction induced by ketone body oxidation. However, despite this blockade, the energy supply to the heart was not impaired as shown by normal nuclear magnetic resonance spectroscopy and cardiac performance. It is speculated, that the blockade might be due to an enhanced NADH/NAD ratio.

Adenosine Triphosphate↗
PubMed1988

One-year follow-up of cardiac and coronary artery disease in infants and children with Kawasaki disease.

Of 75 patients meeting clinical criteria for Kawasaki disease, 67 patients were followed with serial ECG and echocardiograms (echo) for at least 1 year. Sixteen patients had coronary artery aneurysms and three had dilated coronary arteries as assessed by initial two-dimensional (2D) echo and/or angiocardiographic studies. ECG findings of first and second-degree heart block and ST-T wave changes (36%) as well as M-mode echo abnormalities (45%) including pericardial effusion, decreased ventricular septal motion, and decreased left ventricular function were all normalized by 6 months, except in two infants who continued to have decreased function and flat ventricular septal motion. In four patients with single proximal coronary aneurysm and two with dilated coronary artery, resolution of lesions occurred by 1 year. Among 11 patients with multiple coronary aneurysms discovered by initial studies, the 2D echo became normal in seven and showed aneurysms in four as corroborated by angiogram. One patient with an isolated distal coronary aneurysm, not seen by initial or serial echo, had a normal follow-up angiogram. Our study suggests that in Kawasaki disease careful, serial, 2D echo is sufficient to monitor the course of coronary artery disease that tends to regress and follow a benign course. However, the long-term effects of this disease on cardiac and coronary arteries remain to be elucidated.

Child↗
PubMed1988

Cine magnetic resonance imaging for evaluation of congenital heart disease: role in pediatric cardiology compared with echocardiography and angiography.

Cine magnetic resonance imaging was used for preoperative and postoperative evaluation of 91 patients with congenital heart disease. Their ages ranged from 6 weeks to 14 years. The quality of study was excellent in 81% of the cases, in which it provided complete documentation of diagnostic features; substantial diagnostic information was provided in another 14%, and the study was nondiagnostic in only 5%. This technique was most useful for evaluating areas of the right ventricle (95%), great arteries (95%), vena cava (94%), and pulmonary venous system (91%). The anatomic delineation of these areas was comparable to that obtained by cineangiography and was superior to echocardiography, especially in postoperative patients. For complex venous anomalies, magnetic resonance imaging provided better anatomic details than did angiography or echocardiography. The capability of multiplanar imaging allows complex angled views through the desired planes of the heart and great vessels. Proper sedation is essential to obtain maximum diagnostic information. Our preliminary experience suggests that this new modality provides excellent anatomic information in infants and children with congenital cardiac defects and will play an increasing role in pediatric cardiac diagnosis.

Adolescent↗
PubMed1988

Cine magnetic resonance imaging after surgical repair in patients with transposition of the great arteries.

Cine magnetic resonance imaging (MRI) was used for postoperative evaluation of eight patients who underwent intra-atrial baffle procedure for surgical repair of D-transposition of the great arteries (D-TGA). Their ages ranged from 9 months to 8 years. Younger patients were sedated with chloral hydrate (80 to 100 mg/kg) orally. MRI was performed with use of a General Electric Signa system operating at a field strength of 1.5 tesla. A body or head coil was used depending on the size of the patient. Images were obtained by use of a technique of gradient-recalled acquisition in steady state (GRASS) that utilizes a low flip angle and shorter repetition and echo times. Five patients had widely patent venae cavae and three had superior vena caval obstruction at the junction of the right atrium with a dilated azygos vein. There was no evidence of pulmonary venous obstruction in any of the patients. Right ventricular function was assessed in four patients and their ejection fractions ranged from 58% to 81%. Tricuspid and mitral regurgitation were observed in three and two patients, respectively. Both right and left ventricular outflow tracts were well visualized and showed no evidence of obstruction. Cine MRI is an entirely noninvasive, nonionizing, and safe procedure in young patients and appears to be a valuable alternative method for evaluating patients after surgical repair of D-TGA. With advancing technologies and an accumulation of experience with cine MRI, it appears that this new technique will play an important role in patient care for children with congenital heart disease.

Child↗
PubMed1988

Color Doppler flow mapping in patients with coarctation of the aorta: new observations and improved evaluation with color flow diameter and proximal acceleration as predictors of severity.

We performed color Doppler flow mapping in 15 patients, 1 week to 17 years old (mean 42 months), with coarctation of the aorta that was confirmed subsequently by angiography and/or surgery. Twelve patients had native coarctation and three had mild recoarctation after surgical repair. Color Doppler flow maps were analyzed with a digital analysis package and a Sony computer system. The diameter in the region of coarctation from the color Doppler flow map (mean = 2.0 +/- 0.8 mm [SD]) correlated well with the coarctation diameter measured at angiography (mean = 1.8 +/- 0.8 mm; r = .83, SEE 0.43 mm) in the 10 patients with native coarctation undergoing angiography, but the coarctation diameter measured by two-dimensional echocardiography (3.9 +/- 1.5 mm) was poorly predictive of the angiographic severity (r = .23). Additionally, spatial acceleration was seen in all patients proximal to the coarctation site, with an aliased and accelerating stream narrowing progressively as it proceeded toward the coarctation site, a pattern that is not seen in healthy subjects. Computer analysis of the color Doppler images provided pseudo three-dimensional and digital velocity maps for blue, red, and green (turbulent) flow velocities to allow an enhanced appreciation of the accelerating stream, easily separating this from normal descending aortic aliasing patterns. The narrowing of the acceleration area in the proximal descending aorta (distal/proximal acceleration zone ratio) was also predictive of the angiographic severity of coarctation (r = .83). The distribution of low-level turbulence seen proximally paralleled the distribution of the proximal accelerating stream.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1988

Cine magnetic resonance imaging for evaluation of anatomy and flow relations in infants and children with coarctation of the aorta.

Sixteen cine magnetic resonance imaging (MRI) studies were performed in 14 patients aged 1 week to 17 years (mean age, 46 months), who had coarctation of the aorta confirmed at angiography or surgery. Conventional echocardiographic-gated MRI was first performed in axial and rotated sagittal views and was used to identify the slice locations for cine MRI. Cine MRI was performed by gradient-recalled acquisition in steady state with a 30 degree flip angle, 12-msec echo time, 22-msec pulse repetition time, and a 128 x 256 acquisition matrix. Coarctation anatomy was extremely well defined in all but one patient who had vascular clips at the coarctation repair site. The smallest descending aortic flow diameter on cine MRI showed excellent agreement with angiography (r = 0.90). Lucent jets of high-velocity flow through the site of coarctation were imaged in eight patients, and jet length correlated well with the angiographic severity of coarctation (r = -0.81). Two patients were restudied after surgery, and they exhibited excellent repair and normal flow patterns. Cine MRI provides high-resolution imaging of coarctation anatomy with a dynamic spatial and temporal visualization of flow and with excellent detail of vascular anatomy and flow both proximal and distal to the coarctation.

Adolescent↗