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Biomedical subjects

T Hindmarsh

Publications and source records attributed to T Hindmarsh.

At least 19 recordsLinked to original sources
PubMed1992

Magnetic resonance imaging of the brain before and after open heart operations.

Magnetic resonance imaging of the brain was performed in 29 adult male patients before and 1 week after elective coronary artery bypass grafting to study the cerebral effect of cardiopulmonary bypass. The mean age of the patients was 60 years (range, 45 to 69 years). During cardiopulmonary bypass, either a bubble oxygenator without an arterial line filter (n = 9), a bubble oxygenator with a depth adsorption filter (n = 10), or a flat-sheet membrane oxygenator without a filter (n = 10) was used. The mean bypass time was 88 minutes (standard deviation, 31 minutes) and did not differ significantly between the three groups. Preoperative magnetic resonance imaging revealed high signal intensity foci on T2-weighted images (white matter abnormalities) in 17 (59%; 95% confidence limits, 39% to 76%) of the 29 patients, all of which were nonspecific and of the common type considered to be related to aging, and all were unchanged at the postoperative examination. Preoperative and postoperative frontal horn indices, bicaudate diameters, and third ventricle widths did not differ significantly regardless of oxygenator type or whether or not an arterial line filter was used during cardiopulmonary bypass. Two patients (7%; 95% confidence limits, 1% to 23%), both receiving bubble oxygenation (1 without a filter and 1 with an arterial line filter) sustained a cerebral infarction during cardiopulmonary bypass.

Aged↗
PubMed1979

Left ventricular pump function in effort angina.

The successive deterioration of left ventricular pump function during exercise-induced angina pectoris was studied in 20 candidates for aortocoronary bypass surgery. Left ventricular stroke work and power were calculated from continuous left ventricular pressure recordings and repeated measurements of cardiac output every 30 sec using the thermodilution technique. The average left ventricular enddiastolic pressure (LVEDP) increased continuously during exercise whereas stroke work index (SWI) did so only in the beginning of the exercise period up to a maximum value and then fell towards the end of exercise. The onset of angina occurred at an average LVEDP of 34 mm Hg when SWI had already started to fall in most patients. During exercise all patients had markedly lower SWI than normals. Patients with high coronary arteriographic score and patients with a previous myocardial infarction had significantly lower SWI during exercise than those with low score or those without a previous infarct. At rest there were no differences between these groups which emphasises the importance of haemodynamic measurements under stress conditions in patients with ischaemic heart disease.

Adult↗
PubMed1978

Attenuation values of the cerebrospinal fluid (CSF).

The attenuation value of CSF, obtained by lumbar puncture, was determined with computed tomography in 25 patients. Measurement of the protein content in the same samples showed no correlation with the attenuation value. It is concluded that in the normal range of protein concentrations, the effect on the attenuation is insignificant and that the attenuation value of the CSF might be used to check large deviations in the CT numbers due to artifacts.

Brain↗
PubMed1978

Attenuation changes of the ventricular CSF after intravenous injection of contrast material.

The CT attenuation change of the intraventricular CSF after i. v. administration of contrast material has been studied in 20 patients. A very small increase of attenuation was observed in the entire material. The method does not seem to be appropriate at present for the study of small attenuation changes in the CSF reflecting the passage of contrast material.

Adolescent↗
PubMed1978

Lumbo-omental shunt for drainage of cerebrospinal fluid in hydrocephalus.

A new cerebrospinal fluid (CSF) shunting procedure is presented. By transposing a pedicle graft of the greater omentum to the lumbar CSF compartment, the CSF absorption capacity of the omentum is utilized. The operation is applicable to the treatment of communicating hydrocephalus. The technical problems and physiological effects of the operation have been studied earlier in dogs. This paper presents the first case of an intended clinical series. The patient was studied for 18 months postoperatively by different examinations, including psychometric tests, cisternography, computer tomography, echo-ventriculography, and carotid angiography with measurement of the cerebral blood flow. A gradual improvement in his clinical state was registered after the operation.

Cerebrospinal Fluid Shunts↗
PubMed1977

Metrizamide in selective cervical myelography.

The various techniques of cervical myelography are discussed and a technique is described to examine the cervical region after lumbar injection of the contrast medium. This technique is considered less hazardous than other techniques including application of the contrast medium by direct puncture in the cervical region and is advocated for use in patients who have free circulation of CSF and who do not have marked deformity or marked rigidity of the spine.

Humans↗
PubMed1977

Myelography with metrizamide in infants and children.

Technical aspects on myelography in pediatric patients with the water-soluble contrast medium metrizamide (Amipaque) are reviewed. Special interest is paid to site of puncture, positioning of the patients and concentration and dosage of the medium.

Adolescent↗
PubMed1977

Computer cisternography for evaluation of CSF flow dynamics. Further experiences.

Technical aspects of computer cisternography are discussed and the clinical results obtained are reported. The physiologic and morphologic information gained with computer cisternography is superior to that obtained with isotope cisternography. Some recent observations concerning the penetration of the medium into the central nervous system are also discussed.

Cerebrospinal Fluid↗
PubMed1977

Radiopaque marker in the tilting disc of the Björk-Shiley heart valve. Evaluation of in vivo prosthetic valve function by cineradiography.

This paper describes a new, noninvasive method for evaluating the in vivo function of the Björk-Shiley tilting disc valve in the aortic, mitral, and tricuspid positions. The tilting disc was equipped with a ring-shaped radiopaque marker, which permits visualization of the motion of the disc by both cineradiographic and fluoroscopic studies. A beam direction corresponding to the axis of motion of the disc should be sought for calculation of the prosthetic opening angle, whereas prostehtic valve closure is demonstrated by a beam direction deviating 20 to 30 degrees from the valve ring plane. Complete opening to 60 degrees and closure of the prosthetic valve, indicating free motility of the tilting disc, were confirmed by cineradiograms. The error of estimation of the in vivo opening angle is small with deviations of less than 15 degrees from the ideal beam direction and negligible for opening angles approaching 60 degrees. Deviations in two planes simultaneously cause less error than deviation in one plane. The radiopaque marker was designed to detect mechanical valve failure owing to thrombotic obstruction. The incidence of this particular complication was 8.1 per 100 patient-years after aortic valve replacement without anticoagulation treatment. With anticoagulation, this incidence was zero after aortic and 2.5 after mitral valve replacement. In our clinical experience to date, which comprises over 1,250 implants, we have not encountered a single case of primary mechanical valve dysfunction. Our current program includes a change-over to the radiopaque tilting-disc model of the Björk-Shiley prosthesis, which was introduced at this clinic in March, 1975.

Aortic Valve↗
PubMed1975

Lumbar myelography with meglumine iocarmate and metrizamide.

Metrizamide and meglumine iocarmate (Dimer-X), which at present are the contrast media for myelography best tolerated by central nervous system, were compared in a double-blind test comprising a total of 86 patients, all with symptoms of lumbar or sacral root involvement. Symptoms appearing were recorded using a standard interview formula 24 hoaurs after myelography. EEG, routine laboratory analyses of CSF and neurologic examinations were also made. In some cases CSF paper electrophoresis, CSF pressure recordings and determination of CSF iodine content were obtained.

Adult↗
PubMed1975

Myelography in metastatic lesions.

The radiologic appearances at gas myelography were analysed in 57 metastatic lesions, all histologically verified, or having known primary tumours. Five of these cases were also examined with a water-soluble contrast medium, metrizamide. The results were correlated to the findings at surgery and to tumour pathology. It is concluded that myelographic findings simulating juxtamedullary growth are usually due to local indentation of the dura by the extradural tumour, and not to intradural extension.

Adolescent↗
PubMed1975

Elimination of water-soluble contrast media from the subarachnoid space. Investigation with computer tomography.

Contrast media injected into the subarachnoid space may be eliminated in two different ways, by diffusion through the meningeal membranes or by transport through these CSF pathways. The latter mode of transport may be examined using computer assisted tomography of the head. Diffusion predominants with contrast media of low molecular weight, such as methiodal sodium. The transport through the CSF cihculation increases when contrast media of high molecular weight such as meglumine iocarmate and metrizamide are used.

Diagnosis, Computer-Assisted↗