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Biomedical subjects

E J Baker

Publications and source records attributed to E J Baker.

At least 55 records · Page 3Linked to original sources
PubMed1991

Double-outlet right ventricle: morphologic demonstration using nuclear magnetic resonance imaging.

Sixteen patients with double-outlet right ventricle, aged 1 week to 29 years (median 5 months), were studied with a 1.5 tesla nuclear magnetic resonance (NMR) imaging scanner. Two-dimensional echocardiography was performed in all patients. Thirteen patients underwent angiography, including nine who underwent subsequent surgical correction. Three patients underwent postmortem examination. Small children and infants were scanned inside a 32 cm diameter proton head coil. Multiple 5 mm thick sections separated by 0.5 mm and gated to the patient's electrocardiogram were acquired with a spin-echo sequence and an echo time of 30 ms. A combination of standard and oblique imaging planes was used. Imaging times were less than 90 min. The NMR images were technically unsuitable in one patient because of excessive motion artifact. In the remaining patients, the diagnosis of double outlet right ventricle was confirmed and correlated with surgical and postmortem findings. The NMR images were particularly valuable in demonstrating the interrelations between the great arteries and the anatomy of the outlet septum and the spatial relations between the ventricular septal defect and the great arteries. Although the atrioventricular (AV) valves were not consistently demonstrated, NMR imaging in two patients identified abnormalities of the mitral valve that were not seen with two-dimensional echocardiography. In one patient who had a superoinferior arrangement of the ventricles, NMR imaging was the most useful imaging technique for demonstrating the anatomy. In patients with double-outlet right ventricle, NMR imaging can provide clinically relevant and accurate morphologic information that may contribute to future improvement in patient management.

Angiography↗
PubMed1991

Transcatheter embolization in the treatment of coronary artery fistulas.

Seven patients with a coronary artery fistula underwent percutaneous transcatheter embolization (five were male and two female; the age range was 2 to 67 years [median 17]). Three patients were symptomatic. The left to right shunt ranged from 1.6 to 2.6:1. In six patients, the fistula was an isolated congenital anomaly; in one, it was acquired. The fistula arose from branches of the left (n = 5) and right (n = 2) coronary arteries and drained to the right ventricle (n = 2), right atrium (n = 2), coronary sinus (n = 1), pulmonary artery (n = 1) and a bronchial artery (n = 1). Different embolization techniques were used to occlude eight feeding arteries. The embolization materials included a detachable balloon (n = 3), coaxial embolization with platinum microcoils (n = 3), a combination of detachable balloon and microcoil (n = 1) and standard steel coils (n = 1). Satisfactory occlusion was achieved in six patients. In one case, the valve of the detachable balloon was damaged, resulting in early balloon deflation and a residual fistula. There were no associated complications in any patient. Follow-up investigation by Doppler ultrasound or coronary angiography 4 months to 4 years later showed that permanent occlusion was achieved in all six patients in whom embolization was initially successful. Transcatheter embolization should be considered the treatment of choice for coronary artery fistulas.

Adolescent↗
PubMed1991

Costal fringe.

Costal fringe consists of a bandlike pattern of venous telangiectases along the anterolateral costal margins. It is a common and easily recognized entity, usually seen in elderly men. Association with underlying disease is not well established. To assess the frequency of costal fringe in a healthy young adult population, we examined 1523 active duty Air Force personnel (1203 men and 320 women) between the ages of 17 and 34 years. All subjects were human immunodeficiency virus seronegative; none had known hyperestrogenic or other disease states. Costal fringe was present in only three individuals, all men, a frequency of 0.2%. Costal fringe is a rare finding in healthy young adults.

Adolescent↗
PubMed1990

Magnetic resonance imaging of the great arteries in infants.

Sixty infants, aged 1-48 (median 8) weeks, with suspected congenital heart disease underwent a morphological evaluation of the great arteries using magnetic resonance imaging at 1.5 Tesla. Cross-sectional echocardiography was performed in all infants, angiography in 33 and surgery in 44. Multiple sections, 5 mm thick and gated to the patients' electrocardiogram were acquired in standard and oblique imaging planes. Ventriculo-arterial connexions were correctly identified in 54 infants (6 did not have intracardiac imaging performed) and an accurate description of the relationships of the great arteries was made in all. Magnetic resonance imaging clearly demonstrated normal and hypoplastic pulmonary arteries to the level of the first hilar branches and was better than echocardiography at confirming the presence or absence of central intrapericardial pulmonary arteries in 4 infants with pulmonary atresia. All parts of the thoracic aorta were accurately demonstrated and, in 23 infants with clinical suspicion of aortic coarctation, magnetic resonance images provided more information than echocardiography. Magnetic resonance imaging accurately demonstrates great arteries non-invasively supplementing echocardiographic and angiographic findings. In many cases, it replaces the need for invasive investigations.

Aorta, Thoracic↗
PubMed1990

Doppler evaluation of superior caval venous pathways after Mustard and Senning operations.

Doppler waveforms from the superior caval vein were analysed to evaluate the patency of superior caval venous pathways following venous redirection (Mustard and Senning) operations for complete transposition. The group consisted of 26 unselected survivors of Mustard (9 patients) and Senning operations (17 patients). Patients were examined a mean of 5.9 (range 0.1-15.3) years following operation and their age at study ranged from 0.4-25.3 years, mean 7.3 years. Doppler waveforms were correlated with digital subtraction angiograms, which were performed in every patient within 24 hours of the Doppler study. Totally occluded superior caval venous pathways were identified in 3 patients with digital subtraction angiography. The remaining patients had angiographically patent pathways. In the 23 patients with patent pathways, Doppler waveforms demonstrated an initial systolic peak smaller than a second diastolic peak. In the 3 patients with totally occluded pathways, the pattern of the waveform was reversed, with the systolic larger than the diastolic peak. Doppler examination of the superior caval vein is a quick and simple bedside method of accurately determining patency of superior caval venous pathways after atrial redirection procedures for complete transposition.

Adolescent↗
PubMed1990

Enhancement of the clinical margins of Bowen's disease by acetowhitening.

Acetic acid was applied preoperatively to 12 lesions of Bowen's disease to determine if acetowhitening could more clearly define clinical margins. Acetowhitening disclosed the true margins better than unenhanced direct visualization, and subclinical extension of Bowen's disease was revealed by acetowhitening in three lesions. Acetowhitening can be a useful adjunct in the surgical management of Bowen's disease.

Acetates↗
PubMed1990

Balloon dilatation of critical stenosis of the pulmonary valve in neonates.

Percutaneous balloon dilatation was attempted in 15 consecutive neonates (mean age 7.3 (range 1-27) days and weight 3.2 (range 2.5-4.1) kg) with critical stenosis of the pulmonary valve. Dilatation was successful in 11 (73%) patients. The mean balloon to annulus ratio was 1.1 (range 0.6-1.77). The ratio of right ventricle to femoral artery systolic pressure decreased from a mean (1 SD) of 1.4 (0.32) before to 0.8 (0.24) after dilatation and the transvalvar gradient decreased from 81 (29.7) mm Hg before to 33 (27.7) mm Hg after dilatation. All four (27%) patients in whom dilatation was unsuccessful underwent surgical valvotomy. Complications of balloon dilatation occurred in three (20%) patients; these included retroperitoneal haematoma (one) and iliofemoral venous occlusion (two). In one (7%) patient severe hypoxia and hypotension developed when the valve was crossed with a guide wire and balloon catheter. Despite successful dilatation he died 7 days after the procedure. During a mean (1 SD) follow up of 2 (1.7) years, seven (64%) of the 11 patients remained free of important restenosis. One patient required repeat dilatation three weeks after the initial procedure. In three (27%) patients restenosis developed 4-9 months after dilatation and all three had surgical valvotomy. Of the four patients initially referred for surgery three required a second operation and one required balloon dilatation. Percutaneous balloon dilatation gave effective relief of critical pulmonary stenosis in most neonates but complications and restenosis requiring surgery were common.

Blood Pressure↗
PubMed1990

Morphological evaluation of atrioventricular septal defects by magnetic resonance imaging.

Twelve patients aged between 2 weeks and 22 months (median 6 weeks) with atrioventricular septal defects were examined with a 1.5 T, whole body, magnetic resonance imaging system. Ten patients had a common atrioventricular orifice (complete defect) while two patients had separate right and left valve orifices (partial defect). Associated cardiac malformations included the tetralogy of Fallot in two, isomerism of the right atrial appendages and pulmonary atresia in two, and right isomerism and double outlet right ventricle in one. All had previously been examined by cross sectional echocardiography. Eight subsequently had angiography and six underwent surgical correction. There was one operative death and three other deaths. Three of these patients underwent postmortem examinations. Small children and infants were scanned inside a 32 cm diameter head coil. Multiple electrocardiographically gated sections 5 mm thick, separated by 0.5 mm, were acquired using a spin echo sequence with echo time of 30 ms. A combination of standard and oblique imaging planes was used. Magnetic resonance imaging was more accurate than echocardiography in predicting the size of the ventricular component of the defect. It was also better than either echocardiography and angiography in identifying the presence of ventricular hypoplasia. All these findings were confirmed by surgical or postmortem examinations or both. Magnetic resonance imaging is capable of providing detailed morphological information in children with atrioventricular septal defects which is likely to be of value in their management.

Abnormalities, Multiple↗
PubMed1990

An evaluation of right and left ventricular function after anatomical correction and intra-atrial repair operations for complete transposition of the great arteries.

Anatomical correction of complete transposition of the great arteries has the potential advantage over intra-atrial repair in that the left ventricle becomes the systemic pump. To investigate the importance of this, we evaluated right and left ventricular function in 21 patients after anatomical correction and in 21 patients after Mustard or Senning operations. First-pass and equilibrium-gated radionuclide angiography were used to measure right and left ventricular ejection fractions between 17 and 78 (mean, 47) months after anatomical correction and between 3 and 187 (mean, 67) months after intra-atrial repair. The mean age of the patient groups at the time of study was 52 and 84 months, respectively. The right ventricular ejection fraction ranged from 35% to 78% (mean, 58%) in patients after anatomical correction and from 27% to 68% (mean, 51%) after intra-atrial repair (p = 0.066). The left ventricular ejection fraction ranged from 39% to 74% (mean, 58%) after anatomical correction and from 35% to 74% (mean, 58%) after intra-atrial repair (p = 0.86). The mean right and left ventricular ejection fractions of both groups were significantly lower than those of normal children. Individuals with systemic ventricular dysfunction were identified after both types of operations; however, symptomatic dysfunction occurred only after intra-atrial repair (p = 0.24).

Cardiac Surgical Procedures↗
PubMed1989

Accelerated poly(A) loss on alpha-tubulin mRNAs during protein synthesis inhibition in Chlamydomonas.

Detachment of flagella in Chlamydomonas reinhardii stimulates a rapid accumulation of tubulin mRNAs. The induced tubulin mRNAs are normally rapidly degraded following flagellar regeneration, but inhibition of protein synthesis with cycloheximide prevents their degradation. alpha-Tubulin poly(A) tail lengths were measured during normal accumulation and degradation, and in cycloheximide-treated cells. To measure alpha-tubulin mRNA poly(A) chain lengths with high resolution, specific 3' fragments of alpha 1- and alpha 2-tubulin mRNAs, generated by RNase H digestion of mRNA-oligonucleotide hybrids, were sized by Northern analysis. Both alpha-tubulin mRNAs have a newly synthesized poly(A) chain of about 110 adenylate residues. The poly(A) tails shorten with time, and show an average length of 40 to 60 adenylate residues by 90 minutes after deflagellation, at which time induced alpha-tubulin mRNA is being rapidly degraded. Poly(A) loss is significantly accelerated in cycloheximide-treated cells, and this loss is not attributible simply to the longer time the stabilized molecules spend in the cytoplasm. A large fraction of alpha-tubulin mRNA accumulates as mRNA with very short poly(A) tails (less than 10 residues) in the presence of cycloheximide, indicating that deadenylated alpha-tubulin mRNAs can be stable in vivo, at least in the absence of protein synthesis. The rate and extent of poly(A) loss in cycloheximide are greater for alpha 2-tubulin mRNA than for alpha 1-tubulin mRNA. This difference cannot be attributed to differential ribosome loading. This finding is interesting in that the two mRNAs are very similar in sequence with the exception of their 3' untranslated regions.

Base Sequence↗
PubMed1989

Magnetic resonance imaging of coarctation of the aorta in infants: use of a high field strength.

Nineteen infants with suspected coarctation of the aorta were studied with electrocardiographically gated magnetic resonance imaging on a 1.5 T whole body imaging system. In all cases imaging was successful and produced diagnostic images of high resolution. Coarctation was shown in 12 cases. The position and shape of the coarctation were well displayed by the magnetic resonance images. In addition, they clearly showed the relation of the coarctation to arteries arising from the aortic arch and to the length and diameter of the aortic isthmus and the distal aortic arch. The anatomy was confirmed at operation in all 12 patients, except for two with a small ductus arteriosus (arterial duct), which was not seen in the magnetic resonance images. In the seven remaining patients, coarctation was excluded. Magnetic resonance imaging produced high quality images that showed the anatomy better than other non-invasive methods. It provided all the anatomical information required for surgical correction.

Aorta, Thoracic↗
PubMed1989

Magnetic resonance imaging at a high field strength of ventricular septal defects in infants.

Magnetic resonance imaging at a high field strength has potential benefits for the study of the heart in infants, which is when most congenital heart disease presents. Seventeen infants with various anatomical types of ventricular septal defect were studied by this technique. Good quality, high resolution, images were obtained in every case. There were no major practical problems. The morphology of the defects in all 17 hearts was displayed in great detail. In some instances, the interpretation of the images resembled that of equivalent images from cross sectional echocardiography. But this new technique allowed imaging in planes that cannot be obtained by echocardiography. One particularly valuable plane gave a face on view of the inlet and trabecular components of the septum. This allowed very precise localisation of defects in these areas. The relation between the defects and the atrioventricular and arterial valves was exceptionally well shown in various different imaging planes. One patient in the series had multiple trabecular defects that were clearly shown. Magnetic resonance imaging gives detailed morphological information about ventricular septal defects.

Heart Septal Defects, Ventricular↗
PubMed1988

Cineangiographic spectrum of Ebstein's malformation: its relevance to clinical presentation and outcome.

Eight heart specimens were examined that had concordant connections of the cardiac segments and exhibited Ebstein's malformation. The displacement of the leaflets of the tricuspid valve from the atrioventricular junction varied from minimal and isolated involvement of the septal leaflet to involvement of the mural and anterosuperior leaflets as well. This resulted in a wide range of physiologic "atrialization" of the right ventricle. The distal insertion of the valve leaflets also exhibited a spectrum of malformation. At one end the insertion was the normal focal variety, allowing free communication between the atrialized and functional parts of the right ventricle. At the other end there was abnormal linear attachment of the anterosuperior and mural leaflets to an anomalous muscular shelf at the junction between the inlet and apical trabecular portions of the right ventricle. The anteromedial commissure between the anterosuperior and the displaced septal leaflets provided a "keyhole" communication between the two ventricular compartments. Between these extremes were cases in which hyphenations along a locus of linear attachment allowed additional communications between the ventricular compartments. In light of these anatomic observations, cineangiograms of 26 patients with Ebstein's malformation were reviewed retrospectively. It was possible to classify the patients into three groups with focal, hyphenated and linear attachment, respectively. Size, ejection and displacement indexes of the functional right ventricle measured from the angiograms suggested that the severity of the malformation increased from focal attachment through hyphenated to linear attachment. Clinical observations relative to symptoms (cyanosis at rest, reduced exercise tolerance) and outcome supported this morphologic-angiographic grading.

Child↗
PubMed1988

A quantitative evaluation of aortic regurgitation after anatomic correction of transposition of the great arteries.

Twenty patients who had undergone anatomic correction of transposition of the great arteries were assessed by Doppler echocardiography or cardiac catheterization, or both, to identify the presence of aortic regurgitation. The severity of aortic regurgitation was evaluated by radionuclide angiographic measurement of the stroke volume index a mean of 47.1 months postoperatively. The stroke volume index was defined as the ratio of the stroke counts between the left and right ventricles. A value greater than 1.8 was considered to indicate significant left ventricular volume overload. Eight patients (40%) were shown to have various degrees of aortic regurgitation by Doppler echocardiography or cardiac catheterization, or both. The mean (+/- SD) stroke volume index was 1.03 +/- 0.15 in these patients and 1.01 +/- 0.21 in the 12 patients without aortic regurgitation (p = NS). The stroke volume index was not above the normal range in any patient, indicating that the degree of aortic regurgitation present was trivial. This medium-term study indicates that trivial or mild aortic regurgitation is a frequent finding after anatomic correction of transposition of the great arteries. However, it rarely results in an audible cardiac murmur or significant left ventricular volume overload. Long-term evaluation is required to determine its importance.

Aortic Valve Insufficiency↗