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Biomedical subjects

T L Hsu

Publications and source records attributed to T L Hsu.

At least 73 records · Page 4Linked to original sources
PubMed1991

Panoramic transesophageal echocardiography. Clinical application of real-time, wide-angle, transesophageal two-dimensional echocardiography and color flow imaging.

Panoramic transesophageal echocardiography is a new development in transesophageal echocardiography (TEE) technology, which yields a wide-angle imaging field for real-time two-dimensional and color flow imaging. We report our early experience in patients with the use of an annular-array TEE probe that provides a wide, 270 degrees angle imaging field for two-dimensional echocardiographic imaging. The field of view can, however, be narrowed to 15 degrees . The field of view for color flow imaging can be varied from 180 degrees to 10 degrees . Pulsed-Doppler recordings of flow velocity are also possible. This TEE system provides a panoramic vision of cardiac and paracardiac structures from the esophagus and stomach. Besides cardiovascular structures, other thoracic and upper abdominal organs can be visualized. The wide field of view allows a better comprehension of the cardiac anatomy and its relationship with adjacent structures. The initial experience suggests that this method, besides providing the usually required diagnostic information, may have a number of additional applications. Its clinical potential and directions for future developments are reviewed.

Blood Vessels↗
PubMed1991

Intracardiac echocardiography. Experimental observations on intracavitary imaging of cardiac structures with 20-MHz ultrasound catheters.

Recently catheter-based ultrasound devices have become available for obtaining high-resolution images of blood vessels. In this study we evaluated the feasibility of imaging cardiac structures using 20-MHz ultrasound catheters. In 25 dogs, the ultrasound catheter was advanced into the right and left heart chambers percutaneously. The intravascular devices yielded images of the right atrial wall, right and left ventricular myocardia, tricuspid, pulmonic, and aortic valves, and the great vessels. Although the small depth of field inherent to the frequency range of 20 MHz limited the visualization to only portions of the cardiac chambers, the images obtained were of high resolution and allowed easy identification of the various cardiac structures. Intracardiac echocardiography was easy to perform and did not result in damage to the cardiac structures. We conclude that intracardiac echocardiography using ultrasound catheters provides a new approach to cardiac imaging and that the development of lower frequency catheters could aid in extending the potential utility of intracardiac echocardiography.

Animals↗
PubMed1991

Resonance. The missing phenomenon in hemodynamics.

To simulate a short segment of the aorta, we studied wave propagation in an elastic tube with a side branch balloon. The small balloon simulated the organ (group of arterioles). Ligation of this side branch would reduce the moduli of the higher harmonics when the length of the side branch was appropriate. Electrical analogy of vessels was used to analyze this phenomenon. This simulation can explain the ligation results we found in rats. It may also clarify the discrepancies between the prediction of the Womersley equation and the experimental results. We suggest that the aorta and the closely attached organ can produce coupled oscillation; theoretically, this structure is equivalent to a resonance circuit.

Animals↗
PubMed1991

Detection of acute myocardial infarction by evaluation of ultrasonic gray levels in dogs.

The study tested whether an experimental myocardial infarction can be detected from two-dimensional echocardiograms (2DE) by analysis of regional gray levels. The mid-left anterior descending coronary artery was ligated for 3 hours in 14 dogs (group 1) and for 5 hours in 6 dogs (group 2). 2DE were performed before, and after 3 and 5 hours of coronary artery ligation. The ultrasonic amplitude of the control and infarcted regions were obtained from digitized 2DE in the short axis view, at the mid-papillary muscle level. The mean gray levels (+/- SD) of the control and infarcted regions were compared during end-diastolic stop frames. After sacrifice, the hearts were cut into 1 cm thick slices and stained with 1% triphenyl tetrazolium chloride (TTC) solution. The myocardium was then studied by light microscopy. Computerized tomographic scans were also obtained in vitro from 3 hearts of both groups. There was no difference in mean gray levels of the control region during the experiments. However, in the region of wall motion abnormality (area of infarction), the mean gray levels increased from 49.9 +/- 3.5 (before ligation) to 62.0 +/- 7.4 (after 3 hours of ligation, p less than 0.005) in 10 group 1 dogs, but no differences were seen in mean gray levels (49.6 +/- 3.8 vs 50.4 +/- 4.0) in those without a myocardial infarction in 4 group 1 dogs; gray levels also increased from 50.4 +/- 2.9 (before ligation) to 58.6 +/- 6.1 (after 3 hours of ligation, p less than 0.05) and to 65.0 +/- 4.2 (after 5 hours of ligation, p less than 0.005) in group 2 dogs. The area of left ventricular asynergy corresponded precisely to the area of myocardial infarction, determined by both TTC staining and the computerized tomographic scans. The light microscopy of the infarcted area also demonstrated interstitial edema and polymorphonuclear cell infiltration.

Animals↗
PubMed1990

Transesophageal Doppler color flow mapping assessment of atrial septal defect.

Transesophageal Doppler color flow imaging was performed in 19 adult patients (mean age 35 years) with an atrial septal defect demonstrated by cardiac catheterization or at surgery, or both. The transesophageal study correctly identified and classified 19 of 19 shunts in contrast to 16 of 18 shunts identified by the transthoracic approach. The area of the atrial septal defect was calculated by assuming it to be circular and taking the maximal Doppler color flow jet width at the defect site as its diameter. The pulsed Doppler sample volume was placed parallel to the shunt flow direction at the defect site to obtain the mean velocity and flow duration. From these values, the shunt volume was calculated as a product of the defect area, mean velocity, flow duration and heart rate. The calculated shunt flow volume obtained by transesophageal study showed a good correlation with shunt flow volume (r = 0.91, p less than 0.001) and pulmonary to systemic blood flow ratio (r = 0.84, p less than 0.001) obtained at cardiac catheterization. The size of the defect by transesophageal Doppler color flow mapping correlated fairly well with the size estimated at surgery (r = 0.73, p = 0.004). It is concluded that transesophageal Doppler color flow imaging is useful in the detection and classification of atrial septal defects and in the assessment of shunt volumes.

Adult↗
PubMed1990

Usefulness of echocardiography in the prediction of early results of catheter balloon mitral valvuloplasty.

Catheter balloon mitral valvuloplasty (BMV) was performed in 50 patients and 32 of them undergoing BMV with double balloon technique were studied to evaluate the usefulness of echocardiography in the prediction of early results of BMV. Five echocardiographic variables including mitral valve motion, mitral valve thickness, subvalvular change, commissural calcification and left atrial dimension were evaluated. Each variable was divided into mild, moderate and severe subgroups. Before valvuloplasty there were no differences in mitral valve area among any subgroup for any variable. After valvuloplasty, variables associated with a greater increase in mitral valve area from mild and moderate subgroups than from severe subgroup included mitral valve motion, mitral valve thickness, and subvalvular change, but not commissural calcification or left atrial dimension. We scored the former 3 variables as 0, 1 and 2 points in the mild, moderate and severe subgroups, respectively. The sums of individual scores in these 3 variables were further divided into 3 groups: 12 patients had a lower score (less than 2), 10 patients had a score of 3-4 and 10 patients had a higher score (greater than 5). Patients with lower scores tended to have greater increases in mitral valve areas after valvuloplasty than those with higher scores. Thus, mitral valve motion, mitral valve thickness and subvalvular change may be useful to predict a greater increase in mitral valve area after valvuloplasty. A lower score of echocardiographic variables anticipates successful balloon mitral valvuloplasty, which may be helpful in patient selection.

Adult↗
PubMed1990

Detection of dysfunctioning mitral prosthetic regurgitation: transesophageal echocardiography in comparison with transthoracic echocardiography and angiography.

Transesophageal echocardiography has been increasingly used in addition to the transthoracic approach. It not only allows an unobstructed window for viewing the left atrium, but also provides high-quality imaging to improve diagnosis of prosthetic valve dysfunction. To determine the value of transesophageal echocardiography in detection of dysfunctioning mitral prosthetic regurgitation, 11 patients clinically suspected of dysfunctioning mitral prosthesis were studies by transthoracic, transesophageal echocardiography and was documented by a left ventricular angiography. There were 7 biological tissue valves and 4 metallic Bjork-Shiley valves. Compared with a left ventricular angiography, the transthoracic approach to 8 patients made an underestimation of the grade of regurgitation. The angiographic grading confirmed the transesophageal approach in all patients except one who was graded as mild regurgitation by left ventricular angiography, moderate regurgitation by transesophageal echocardiography, but no regurgitation by transthoracic echocardiography. Our results indicated that in patients with suspected mitral prosthetic dysfunction, a transesophageal echocardiography is more sensitive than a transthoracic echocardiography in detecting mitral regurgitation.

Adult↗
PubMed1987

Endomyocardial fibrosis with massive endocardial calcific deposits.

Massive endocardial calcific deposits in the left ventricular chamber is such an uncommon lesion that only three cases have been reported previously. This report describes an apparently asymptomatic patient with endomyocardial fibrosis and massive endocardial calcific deposits. The results of electrocardiography, echocardiography, angiography, and endomyocardial biopsy findings are presented, and the pathogenesis of massive endocardial calcification is speculated upon. The interesting point is that the clinical history and manifestation of this patient suggests that endomyocardial fibrosis may occur in a benign form and long-term survival may be expected.

Biopsy↗
PubMed1985

Echocardiographic study of cardiac abnormalities in families of patients with Marfan's syndrome.

Twelve patients (5 male and 7 female; mean age 17.7 +/- 12.3 years, range 5 to 42) with Marfan's syndrome and 48 of their first degree relatives (16 male and 22 female; mean age 29.8 +/- 17.3 years, range 4 to 60) were evaluated for cardiac abnormalities by echocardiography. Of the patients with Marfan's syndrome, aortic valve prolapse was present in 1, tricuspid valve prolapse in 4, mitral valve prolapse in 12 and aortic root dilation in 10. Of the 48 first degree relatives of these 12 patients, tricuspid valve prolapse was diagnosed in 3, mitral valve prolapse in 15 and aortic root dilation in 12; aortic valve prolapse was not observed in any of these subjects. Of the 60 persons studied in these 12 kindreds, 28 (47%) had cardiac involvement. Among the 28 with cardiac involvement, aortic valve prolapse was observed in 1 (3.5%), tricuspid valve prolapse in 7 (25%), mitral valve prolapse in 27 (96%) and aortic root dilation in 22 (79%). Mitral valve prolapse was also present in the seven subjects with tricuspid valve prolapse and one with aortic valve prolapse. In 32 of the 60 persons studied in the 12 families, at least one abnormality of the cardiac, skeletal or ophthalmologic system was observed. Nineteen subjects were younger than 18 years of age; all had cardiac involvement associated with Marfan's syndrome. The notably earlier presentation of cardiac involvement in young persons may be responsible for a shorter life span in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

Leukocyte migration-inhibition agarose test in swine after vaccination and challenge with inactivated and activated pseudorabies virus.

Cell-mediated immunity to pseudorabies virus (PrV) was studied by means of the leukocyte migration-inhibition (LMI) agarose test. Migration of leukocytes from swine vaccinated with 10 TCID50 inactivate PrV and from normal control swine was not inhibited in the presence of specific PrV antigen. Cellular immune responses were detected in 80% of the vaccinated and 40% of the control group animals at the 1st week after challenge exposure. At the 2nd week, both groups of swine showed a peak level (p less than 0.001) immune response in the LMI test. This level of response remained until the 3rd week in the vaccinated group and the 2nd week in the control group. The averages of migration indices at the 1st, 2nd, 3rd and 4th weeks after challenge exposure were 0.74, 0.22, 0.60 and 0.89 in the vaccinated and 0.82, 0.29, 1.01 and 1.12 in the control group, respectively. Low concentrations of virus-neutralizing (VN) antibodies were present in 30% of the vaccinated swine at the 1st week, and 60% at the 2nd week after vaccination. Anamnestic antibody and primary VN antibody responses occurred after challenge in vaccinated and normal swine, respectively.

Animals↗
PubMed1980

Glucose transport carrier of human erythrocytes. Radiation-target size of glucose-sensitive cytochalasin B binding protein.

Apparent molecular sizes of D-glucose-sensitive cytochalasin B binding protein of human erythrocyte membranes are assessed by applying classical target theory to irradiation-inactivation data. Molecular weights of this protein as it occurs in untreated ghosts, EDTA-treated ghosts, and reconstituted vesicles of Triton extract of ghosts are 220,000, 180,000, and 220,000, respectively. These results, in conjunction with other findings in the literature, suggest that the native form of the glucose transport carrier of human erythrocytes is a tetrameric assembly of a 50,000-dalton monomer or is a dimer of 100,000 daltons.

Biological Transport, Active↗