Biomedical subjects

G R Sutherland

Publications and source records attributed to G R Sutherland.

At least 667 records · Page 37Linked to original sources

PubMedDate not supplied

Ataxia-without-telangiectasia. Progressive multisystem degeneration with IgE deficiency and chromosomal instability.

Three of five siblings developed a progressive neurological disorder during infancy or early childhood characterized by cerebellar ataxia, choreoathetosis and peripheral neuropathy. Immunological studies revealed a marked selective deficiency of serum IgE in all three affected siblings. There was evidence of chromosomal instability in the three affected siblings and in one of the parents. One of the affected siblings also developed acute lymphoblastic leukaemia. In spite of many resemblances, this syndrome differs from classical or complete ataxia telangiectasia in that oculocutaneous telangiectases were lacking, the serum IgA and alpha-fetoprotein levels in this family were normal, there was no gonadal dysgenesis, and the cytogenetic findings were atypical.

Adolescent↗

PubMedDate not supplied

SCE, X-radiation sensitivity and mutation rate in multiple sclerosis.

In order to detect any underlying DNA abnormality that may be present in multiple sclerosis (MS), the incidence of SCE, X-radiation sensitivity and the frequency of 6-thioguanine-resistant cells were determined in the lymphocytes of 34 MS patients. As a group, MS patients showed an increase in the SCE rate compared to control. However, there was no increase in X-radiation sensitivity. The frequency of 6-thioguanine-resistant mutant cells was also normal.

Crossing Over, Genetic↗

PubMedDate not supplied

The role of nucleotides in human fragile site expression.

Fragile sites are points on chromosomes which tend to break non-randomly when exposed to specific chemical agents or conditions of tissue culture. There are 3 groups of rare fragile sites, and carriers of these range in incidence from about 1 in 20 to 1 in several thousand individuals. Rare fragile sites are essentially chromosome variants with no known phenotypic consequence, except for the fragile X which is associated with the commonest inherited form of mental retardation in man. There are also 3 groups of common fragile sites, carried by all or most individuals. These are part of normal chromosomal architecture. Expression of most of the groups of fragile sites is mediated by perturbations of the nucleotide pool and these, as they relate to each group of fragile sites, are discussed. The rare folate-sensitive fragile sites are expressed when thymidylate or deoxycytidine are in limited supply during DNA synthesis. Other rare fragile sites are induced by bromodeoxyuridine (BrdU). Sets of common fragile sites are induced by BrdU, 5-azacytidine and aphidicolin. Various hypotheses on the molecular nature of fragile sites are considered.

Chromosome Fragile Sites↗

PubMedDate not supplied

The variation of integrated backscatter in human hearts in differing ultrasonic transthoracic views.

It has been shown previously that in normal subjects the interventricular septum imaged in the long-axis view (LAX) and the left ventricular posterior wall imaged in both the LAX and the short-axis view (SAX) exhibit cyclic variation of integrated backscatter (IB) throughout the cardiac cycle, with maximum values occurring at end diastole (ED) and minimum at end systole (ES). The ability to demonstrate this cyclic variation within these myocardial regions in only two ultrasonic views has limited the potential clinical utility of an IB imaging system. To determine whether clinically useful information on the variation of IB is available from different myocardial regions in different ultrasonic views, we measured ED to ES variation of IB from the parasternal and apical views in normal subjects with a radiofrequency acquisition technique. Two independent clinical observers analyzed ED to ES variation of IB from 14 normal volunteers (mean age 32 +/- 6 years; range 21 to 45 years) in reconstructed two-dimensional ultrasonic images obtained from the parasternal LAX and SAX and apical two-chamber (2C) and four-chamber (4C) views. ED to ES variation of IB was measured from manually traced regions of interest (ROI) within the myocardium. These ROIs were chosen interactively and were located within the midposterior wall and the midanteroseptum in LAX views; within the midposterior wall, midanteroseptum, midseptum, and midlateral wall in SAX views; within the midseptum and the midlateral wall in 4C views; and within the midinferior wall and the midanterior wall 2C views. In all analyzed ROIs within the parasternal and apical views, ED to ES variation of IB was found. We have shown that the maximum magnitude of IB was at ES within the midseptum and in 10 out of 14 volunteers in the midanteroseptum measured from SAX views, the midanterior wall from 2C views, and the midlateral wall from 4C views. The rest of the ROIs analyzed exhibited the maximum value of IB cyclic variation at ED. We have confirmed that the ED to ES variation of IB is present not only when measured from the two standard parasternal views but also from the two apical views in all analyzed myocardial walls, and the minimum of this cyclic variation was not always coincident with ES nor the maximum with ED.

Adult↗

PubMedDate not supplied

Safety and efficacy of computerized closed-loop delivery of arbutamine: a new pharmacologic myocardial stress modality for the assessment of coronary artery disease. The European Arbutamine Study Group.

This study evaluated the efficacy of computer-controlled closed-loop delivery of a new synthetic catecholamine, arbutamine, when given to induce myocardial ischemia detected by electrocardiography and echocardiography with a high (10 beats/min/min) and low (6 beats/min/min) rate of increase in heart rate (heart rate slope) in 70 patients with coronary artery disease. The electrocardiographic sensitivity for the detection of myocardial ischemia was 52% for the low slope and 51% for the high slope. The corresponding figures for echocardiographic sensitivity were 83% and 79% for the low and high slopes, respectively. There were no significant differences in changes from baseline to maximum in pharmacodynamic variables, although the mean times to reach maximum heart rate and systolic blood pressure were 1.4 minutes shorter (p = 0.001) and 3.7 minutes shorter (p < 0.05), respectively, for the high-slope regimen. The duration of the infusion was shorter (p < 0.001) for the high slope. In this study, closed-loop arbutamine administration was effective and safe in the detection of coronary artery disease for both heart rate slope regimens.

Adult↗

PubMedDate not supplied

Doppler tissue imaging: myocardial wall motion velocities in normal subjects.

With a scanner modified for Doppler tissue imaging, mean myocardial velocities (MMV) across the myocardium were measured. The aim of this study was to determine the normal range of the maximum MMV in six standardized phases of the cardiac cycle. The MMV was defined as the average value of the myocardial velocity measured along each M-mode scan line throughout the thickness of the myocardium. The maximum MMV was defined as the maximum value of the MMV during the particular cardiac phase. Simultaneous gray-scale and Doppler tissue imaging M-mode images were taken of the interventricular septum and the left ventricular posterior wall from the parasternal long-axis and short-axis views in 15 normal volunteers (aged 21 to 47 years; mean 32 +/- 6 years). Each cardiac cycle was divided into six phases: atrial contraction, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, rapid ventricular filling, and diastasis. Isovolumetric contraction, isovolumetric relaxation, and diastasis were subdivided into two parts a and b because of changes in the direction of the myocardial movement. For each volunteer, the mean and standard deviation of the maximum MMV were measured for each cardiac phase averaged from 12 cardiac cycles from both long-axis and short-axis views. Finally, the mean and standard deviation were taken for each cardiac phase from 180 cardiac cycles from 15 volunteers. We have found that specific cardiac phases show significant differences in the maximum MMV between the adjoining cardiac phases and significant differences also occur between the maximum MMV measured in the interventricular septum and the left ventricular posterior wall during the same cardiac phases. These normal values provide a standard against which future Doppler tissue imaging M-mode studies of abnormal left ventricular function might be compared.

Adult↗

PubMedDate not supplied

Color Doppler myocardial imaging: a new technique for the assessment of myocardial function.

Color Doppler myocardial imaging is a new technique that has been developed specifically to allow color Doppler imaging of myocardial wall motion rather than blood pool imaging. Such a technique has the potential to interrogate velocities, accelerations, and Doppler signal strength within the myocardial wall. Moreover, the concomitant enhancement of the myocardial Doppler signal after an intravenous injection of a transpulmonary echocardiographic contrast agent could permit the noninvasive assessment of regional myocardial perfusion. Thus this new imaging modality could be a valuable adjunct to the ultrasound assessment of myocardial ischemia.

Animals↗

PubMedDate not supplied

A prospective study of left atrial spontaneous echo contrast and thrombus in 100 consecutive patients referred for balloon dilation of the mitral valve.

The aim of this study was to determine the clinical, echocardiographic, and hemodynamic predictors of left atrial spontaneous echo contrast (SEC) and thrombus, respectively, in patients referred for balloon dilation of the mitral valve and to establish the relationship between the two phenomena in this group of patients. One hundred consecutive patients (mean age 57 +/- 14 years) referred for mitral balloon (Inoue) dilation were studied prospectively with transthoracic and transesophageal (83 biplane and 17 single plane) echocardiography (TEE) combined with spectral and color Doppler modalities, immediately before the procedure. TEE was repeated within 24 hours of valvotomy in the first 55 patients. All patients also underwent comprehensive left- and right-sided heart catheterization. TEE was performed successfully in 96 patients. SEC was detected in all 65 patients in atrial fibrillation and in 14 (45%) of 31 patients in sinus rhythm. Patients with SEC were significantly older (61 +/- 13 vs 45 +/- 12 years; p < 0.001) and had larger left atrial volume (98 +/- 48 vs 64 +/- 24 ml; p < 0.001), higher mitral valve echocardiographic scores (7.4 +/- 3.2 vs 5.3 +/- 2.6; p = 0.016), lower cardiac output (3.5 +/- 1.1 versus 4.6 +/- 0.9 L/min; p < 0.001), lower peak systolic pulmonary vein flow velocity (SVm) (24 +/- 12 versus 45 +/- 11 cm/sec; p < 0.001), and correspondingly lower systolic velocity-time integral (4.0 +/- 2.6 vs 7.9 +/- 2.9 cm; p < 0.001) than had patients without SEC. There were no significant associations between SEC and either mitral valve area or anticoagulant therapy. SVm and atrial fibrillation were found to be independent predictors of SEC. In patients in sinus rhythm, SVm was the only independent predictor of SEC. After mitral balloon dilation, SEC disappeared in only two of 35 patients in atrial fibrillation and in five of eight patients in sinus rhythm. Significant mitral regurgitation occurred in the two patients in atrial fibrillation. TEE detected left atrial thrombus in 14 patients. Thrombus was significantly associated with age, mitral valve area, and the severity of SEC. The latter was found to be an independent predictor of thrombus. Two patients in sinus rhythm had evidence of left atrial mechanical dysfunction. Both patients had left atrial SEC and one had thrombus in the appendage. It is concluded that SEC in patients with severe mitral stenosis is dependent on left atrial systolic function and peak systolic pulmonary vein velocity. It is not related to mitral valve area or anticoagulant therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMedDate not supplied

Reference systems in echocardiographic quantitative wall motion analysis with registration of respiration.

Registration of respiration allows analysis at the end-expiratory phase and may thus favor the use of the fixed-reference system versus the floating-reference system in echocardiographic quantitative wall motion analysis. Analysis is performed on two-dimensional echocardiograms of 44 normal subjects, 38 patients with anterior myocardial infarction, and 17 patients with posterior myocardial infarction. Two different models for wall motion analysis are applied, each using the fixed-reference system and the floating-reference system, respectively. In patients with anterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the anterior, septal, and apical walls, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. In patients with posterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the posterior wall, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. These findings indicate that the fixed-reference system is superior to the floating-reference system in quantification of wall motion of end-expiratory two-dimensional echocardiograms.

Adult↗

PubMedDate not supplied

Intraoperative transesophageal versus epicardial ultrasound in surgery for congenital heart disease.

Twenty-eight patients (age range, 0.7 to 65 years; median age, 6.1 years) who were undergoing correction for congenital heart disease were entered into a prospective study with both intraoperative transesophageal and epicardial ultrasound to determine the relative values of these techniques before and after bypass surgery. Introduction of the transesophageal probe was successful in 26 patients (93%); children were studied with use of dedicated pediatric transducers. Epicardial studies were performed in all 28 patients. Epicardial studies allowed for higher resolution imaging and a more complete assessment before bypass surgery of the intracardiac morphological condition (ventricular septum and right ventricular outflow tract) than the assessment that was obtained by the transesophageal approach. In the period immediately after bypass surgery, the transesophageal technique allowed a more detailed insight into atrioventricular valve function (valvar regurgitation [five patients] and ventricular inflow patterns) and the continuous monitoring of left ventricular function and volume. Residual interventricular shunting (three patients) or residual outflow tract obstruction (four patients) could not be reliably documented by transesophageal studies. It is concluded that intraoperative transesophageal and epicardial ultrasound in surgery for congenital heart disease are complementary rather than alternative techniques.

Adolescent↗

PubMedDate not supplied

Posterior left ventricular pseudoaneurysm after aortic valve replacement in a patient with rheumatoid arthritis: diagnosis by transesophageal echocardiography.

A 58-year-old man with seropositive rheumatoid arthritis underwent successful aortic valve replacement because of severe aortic regurgitation. One year later, prosthetic valve endocarditis was suspected clinically and he was referred for echocardiography. On transthoracic echocardiography an unusual echo-free space adjacent to the inferobasal segments of the left ventricle and extending behind the left atrium was visible. No further diagnostic information could be obtained from precordial examinations. Biplane transesophageal echocardiography demonstrated the presence of a pulsatile pseudoaneurysm of the left ventricle arising posteriorly, close to the anulus of the mitral valve. There was no evidence of endocarditis.

Aortic Valve↗

PubMedDate not supplied

Echocardiographic identification of infective endocarditis within a congenital left sinus of Valsalva-right atrial communication.

A rare case is described of infective endocarditis within a congenital left sinus of Valsalva aneurysm to right atrial communication diagnosed by a combination of precordial and transesophageal echocardiography. The respective roles of precordial and transesophageal echocardiography in this case are discussed with regard to both diagnosis and surgical decision making.

Adult↗

PubMedDate not supplied

Transgastric imaging: a valuable addition to the assessment of congenital heart disease by transverse plane transesophageal echocardiography.

Multiview transgastric imaging was performed with standard single transverse plane transesophageal probes in 16 patients to assess its potential additional value in defining the complexities of congenital heart disease. The age of patients studied ranged from 1.1 to 32 years (mean of 10.4 years). Their body weight ranged from 8.3 kg to 69 kg (mean of 29 kg). In all studies, a complete range of transesophageal and transgastric views could be obtained. The information thus obtained was correlated with the findings of prior precordial echocardiography and subsequent cardiac catheterization or surgical inspection. The pathologic conditions studied included tetralogy of Fallot, (4), isolated ventricular septal defect (4), valvular aortic stenosis (1), subvalvular and valvular aortic stenosis (1), supraaortic stenosis (1), total atrioventricular septal defect (1), secundum atrial septal defect (1), double-outlet right ventricle (1), double-chambered right ventricle (1), and pulmonary atresia, ventricular septal defect, and superoinferior ventricles (1). The single-plane data provided by transgastric scanning were compared and contrasted with that obtained from transesophageal scanning. Transgastric views were shown to be superior to transesophageal imaging in demonstrating the anatomy of the right ventricular outflow tract, the left ventricular outflow tract, and the apical and anterior aspects of the ventricular septum. In addition, these views offered a favorable angle of incidence for spectral wave Doppler studies of flow in both outflow tracts. We conclude that transverse plane transgastric imaging is an important addition to the transesophageal assessment of congenital cardiac disease. Its main additional benefit is in the study of lesions that involve either the right or left ventricular outflow tract or the anteroapical ventricular septum. Its main clinical value is likely to be in the evaluation of the perioperative patient in whom diagnostic precordial imaging is frequently impossible.

Adolescent↗

PubMedDate not supplied

Quantitative echocardiographic analysis of global and regional left ventricular function: a problem revisited.

We recorded two-dimensional echocardiograms simultaneously with the respiration measurements of 20 normal subjects and 20 patients with anterior myocardial infarction. The apical long-axis and four-chamber views were quantitatively analyzed. Measurement variability of global ejection fraction and regional ejection fraction of 100 regions was calculated during inspiration and at end-expiration for two observers. To minimize variability, the endocardial contour was redefined and traced with an improved computer-assisted tracing system. Variability (absolute mean difference) between two beats at end-expiration was significantly less than during inspiration (p less than 0.05): for ejection fraction the variability at end-expiration was 3.4% and the variability during inspiration was 6.4% (mean, 54%; SD, 7%); for regional ejection fraction the variability at end-expiration was 11.8% and the variability during inspiration was 21.5% (mean, 56%; SD, 15%). Intraobserver and interobserver variability values of one beat at end-expiration for ejection fraction were 3.1% and 3.8%, respectively, and 9.5% and 12.8%, respectively, for regional ejection fraction. Variability in patients with myocardial infarction was comparable. This method of recording respiration and analyzing left ventricular function at end-expiration, with a new contour definition and tracing system, provides a measurement variability that is considerably less than that reported in previous echocardiographic studies and that is comparable to angiographic methods.

Adult↗

PubMedDate not supplied

Intraoperative epicardial echocardiography: early experience with a newly developed small surgical transducer.

To test the feasibility of performing intraoperative echocardiography with a specially designed epicardial transducer, 20 adult patients were studied. All patients were undergoing coronary bypass surgery and had structurally normal intracardiac anatomy. The surgical transducer has 48 elements and a size at the tip of 10 x 12 x 5 mm. The scan plane has been set at 90 degrees to the cable axis to allow scanning from lateral positions. The terminal 10 cm of the cable has been reinforced to act as a malleable and steerable handle. Good quality images were obtained with the new transducer, and many different imaging planes were identified compared to imaging with the standard transducers. These include the right ventricular apex, the right and left lateral aspects of the heart, the aortic arch, and the pulmonary artery and its branches. The limitation of the probe was the difficulty in obtaining left ventricular apical views because of ventricular arrhythmias sustained when the transducer was placed between the left ventricular apex and the diaphragm. We conclude that this new transducer has a promising future in the application of intraoperative epicardial echocardiography.

Adult↗

PubMedDate not supplied

The value of transesophageal echocardiography in children with congenital heart disease.

With the use of dedicated pediatric single-plane probes, transesophageal echocardiography was performed prospectively in 102 children to determine the potential value of this new technique in the diagnosis (40 patients) and the follow-up of congenital heart disease (29 patients) and as a monitoring technique during the perioperative period or interventional cardiac catheterization (33 patients). The findings were correlated with precordial studies (102 patients), cardiac catheterization (82 patients), epicardial ultrasound findings (18 patients), or surgical inspection (34 patients). The age at investigation ranged from 2.5 months to 14.9 years (mean age, 5.2 years); weight ranged from 3.7 to 52 kg (mean weight, 19.1 kg). Additional information was obtained in 49 patients (48.4%) and was relevant for patient management in 21 patients (20.6%). Major areas of improved diagnostic insight included the following: (1) systemic and pulmonary venous return, (2) atrial morphology, (3) atrioventricular junction abnormalities, (4) left ventricular outflow tract disease, (5) atrial baffle function, and (6) the Fontan circulation. Inherent limitations were as follows: (1) the semiinvasive character of the procedure, (2) the need for heavy sedation or general anesthesia, and (3) the limited imaging planes provided. Transesophageal echocardiography in children can provide important additional diagnostic information on a wide spectrum of congenital heart lesions. The technique would appear to be a highly valuable adjunct to the diagnostic armentarium of the pediatric cardiologist.

Adolescent↗

PubMedDate not supplied

Transesophageal echocardiography.

Two-dimensional transesophageal echocardiography generally has superior sensitivity and image quality compared with precordial echocardiography. Its unique anatomic perspective posterior to the heart often provides important clinical information not obtainable by other imaging approaches and technologies. It is particularly useful in the diagnosis of mitral valve disease, left atrial masses, endocarditis and its sequelae, and aortic dissections. It is also useful for examination of the left main coronary artery, left ventricular outflow tract, atrial and ventricular septa, and congenital defects. In addition to its application as a diagnostic tool in conscious patients, it can be employed intraoperatively to evaluate and guide surgical intervention. Detection of ventricular wall motion abnormalities by transesophageal echocardiography has been shown to be the most sensitive indicator of myocardial ischemia available in the clinical setting. It has potential for wide application for safely monitoring left ventricular function in patients in intensive care or under anesthesia.

Echocardiography↗

PubMedDate not supplied

Doppler myocardial imaging: a new method of data acquisition for three-dimensional echocardiography.

The precise morphologic characteristics of any intracardiac tumor have important implications regarding surgical planning and operative repair. Three-dimensional echocardiography has proved to be a valuable clinical technique in this field. Current methods of three-dimensional reconstruction of two-dimensional images are based on the standard gray-scale imaging technique. However, precordial gray-scale data-set information is frequently of suboptimal quality because of data degradation caused by ultrasound attenuation by chest wall structures. This has limited the use of the transthoracic three-dimensional technique to "echogenic" patients. Doppler myocardial imaging (DMI), a new ultrasound technique based on the Doppler principle, is influenced less by chest wall attenuation and in addition offers a better boundary detection algorithm for the cardiac structures. To determine if there may be a potential benefit of DMI to acquire data for three-dimensional reconstruction, a 33-year-old woman with a large intracardiac mass was studied. In this case three-dimensional gray-scale and DMI data sets were compared and contrasted with pathologic information. DMI allowed both the qualification of mass volume and the correct definition of the morphology of the mass. It was also possible to identify the precise site of attachment of the mass to the mitral valve leaflets. The information thus obtained was correlated with both operative and pathologic findings.

Adult↗