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Biomedical subjects

J Ambrose

Publications and source records attributed to J Ambrose.

At least 37 records · Page 2Linked to original sources
PubMed1983

Coronary thrombosis in the absence of angiographically-evident obstructive coronary disease.

A 31-year-old man with an acute myocardial infarction underwent intracoronary thrombolysis with streptokinase. Post-thrombolytic angiography revealed no underlying obstructive coronary disease. This particular syndrome of a documented thrombus in a normal vessel causing infarction has not previously been described. Such a sequence may explain the occurrence of myocardial infarction in some patients with normal coronary arteries. The mechanism by which thrombus occurs in an angiographically-normal coronary artery is at present undefined.

Adult↗
PubMed1982

Angina pectoris before and after myocardial infarction. Angiographic correlations.

Clinical, hemodynamic, and angiographic data were examined in 97 consecutive patients who underwent catheterization within two years of documented acute transmural myocardial infarction. The patients were divided according to the absence or presence of angina pectoris prior to myocardial infarction (groups 1 and 2). Group 1 had more females, was younger, and had a greater prevalence of one-vessel coronary artery disease. Of the patients surviving the myocardial infarction until hospital discharge, group 1 had fewer cases of postinfarction angina pectoris. The following were not statistically different for the two groups: mean time from infarction to catheterization, location of infarction, heart failure, coronary risk factors, mean left ventricular end-diastolic pressure, and mean ejection fraction. The angiographic significance of angina following infarction was analyzed in the 94 survivors. Patients with angina after infarction had a greater prevalence of two- and three-vessel coronary artery disease compared with patients without angina following infarction. Group 1 patients who had developed angina after infarction also had a greater prevalence of two- and three-vessel disease than patients who had no postinfarction angina. One-vessel disease was found in 82 percent of patients who had no angina before and after infarction. Infarction as the first manifestation of coronary artery disease (group 1) is often associated with one-vessel disease, especially if angina does not appear after infraction. Angina before or after infarction suggests two- and three-vessel disease.

Adult↗
PubMed1981

Coronary flow studies in patients with left ventricular hypertrophy of the hypertensive type. Evidence for an impaired coronary vascular reserve.

Increased myocardial blood flow occurs in ventricular hypertrophy, but flow per 100 grams of myocardium remains normal. The increase in flow may be obtained at the expense of the existing coronary vascular reserve or by an increase in the vascular bed. The coronary vascular reserve was studied by analyzing the hyperemic reaction to selective injection of contrast agent into the coronary arteries in 25 patients: a control group (9 patients) with chest pain syndrome, normal coronary arteries and a normal left ventricle (Group I) and 16 patients with aortic stenosis, left ventricular hypertrophy and normal coronary arteries (Group II). The hyperemic response in Groups I and II was 73.3 +/- 2.2 and 65.8 +/- 9.1 percent, respectively (difference not significant). Group II was subdivided into two groups: Group IIA had five patients with a left ventricular mass of less than 200 g (mean 158.8 +/- 25.9); this group had a hyperemic response of 102.3 +/- 9.9 percent. Group IIB had 11 patients with a left ventricular mass of more than 200 g (mean 308.9 +/- 22.5) and a hyperemic response of 49.27 +/- 10.42 percent. The hyperemic response was correlated with the diastolic left ventricular-aortic gradient (r = +0.64, p less than 0.001), left ventricular mass (r = -0.51, p less than 0.01) and aortic diastolic pressure (r = +0.636, p less than 0.001). Group I had a left ventricular mass similar to that of Group IIA (124.9 +/- 9 and 158.8 +/- 26 g, respectively) but a lower hyperemic response (73.3 +/- 2 and 102.3 +/- 10 percent, respectively). These data suggest that severe left ventricular hypertrophy is associated with a reduction in coronary vascular reserve; it is speculated that this decrease in the vascular reserve capacity may be related to the ischemic component of hypertrophic heart disease.

Adult↗
PubMed1980

Coronary artery spasm and perioperative cardiac arrest.

There has been increasing interest in coronary artery spasm as etiopathogenic mechanism for various syndromes associated with myocardial ischemia. A case with documented organic coronary artery disease is presented, in which coronary artery spasm was the probable cause of intraoperative and early postoperative cardiac arrest. We recommend that coronary spasm be considered in the differential diagnosis of perioperative cardiac arrest.

Angina Pectoris, Variant↗
PubMed1978

The double contrast barium enema: improvements to lateral decubitus views including the use of a wedge filter.

The prognostic importance of early detection of colonic carcinoma is emphasised and the contribution of an accurate barium enema technique is stressed. Horizontal beam lateral decubitus films are routine in double contrast barium enemas, and it is still common practice in many departments to support the cassette for these views either in the bucky tray or with sandbags. The lateral decubitus views of 100 patients using these methods of cassette support were reviewed. A large number of the films (67%) were technically so unsatisfactory due to unilateral under- or over-penetration that they did not provide acceptable visualisation of the colon. The cause of these technical faults, and the methods by which they may be overcome, are described. In addition, a wedge filter was designed to reduce the absorption by dependent soft tissues in obese patients.

Barium Sulfate↗
PubMed1976

E.M.I. scan in the management of head injuries.

The E.M.I. scan has much simplified the management of head injuries. The conventional investigations have been supplanted by a safe non-invasive technique, in which lesions of the brain can be demonstrated. Thus high density intracerebral or extracerebral haematoses are readily diagnosed, even when they are in unusual sites. Wherever their location, they appear in sharp contrast to the low density of cerebral contusions or chronic subdural haematomas. The safety of the procedure recommends its sequential use in patients who fail to improve or who deteriorate; and repeated examinations can be useful in monitoring the response to therapy. Under clinical supervision, the quantity and quality of information the method yields during a single comprehensive study is such that it should became the definitive investigation in the victims of cerebral trauma.

Angiography↗
PubMed1976

Computerized axial tomography: estimation of spatial and density resolution capability.

The spatial and density resolution capability of the EMI-Scanner device for computerized axial tomography has been determined in vitro. For density differences greater than +/-1 per cent the spatial resolution is 6 X 6 mm. For density differences of 3 per cent and greater the resolution is 3 X 3 mm. Density resolution is at least +/-1 per cent for objects greater than 1 cm. Preliminary data on in vitro measurement of X-ray linear attenuation coefficients in tissue biopsies and standard solutions are given, together with the early results of enhancement of tissue density differences in vivo. Implications of this new technique for an in vivo neuropathology are suggested.

Brain Diseases↗
PubMed1976

A quantitative study of the EMI values obtained for normal brain cerebral infarction and certain tumours.

A quantitative study has been made of the EMI numbers of normal brain, cerebral infarction and certain tumours. The scans were recorded on magnetic tape and analysed using a minicomuter linked to a graphic display unit. This system not only yielded 16 grey scales compared with the ten currently available, but was programmed to allow selected regions of the scans to be outlined. From these regions the computer calculated the area, the mean EMI number and its standard deviation. It was found that in 15 normal brain scans, the EMI values obtained for normal frontal and temporal lobes were similar, but that the values for the basal ganglia and occipital lobes were significantly different from the first two regions and from each other. Ten cases of cerebral infarction and 30 cases of cerebral tumour were analysed, and it was shown that analysing representative areas was more informative than surveying the whole lesion. Whilst only half of the scans of brain tumours had a significantly altered EMI number compared with that of normal brain, enhancement of tumour density with sodium iothalamate revealed a consistent and significant elevation of the EMI number for all tumours. In particular, the value for enhanced meningiomas was almost double and malignant tumours more than a third larger than normal brain. It was not possible to differentiate quantitatively between astrocytomas and metastases.

Brain↗
PubMed1975

The Lancet - Saturday II October 1975. Sodium iothalamate as an aid to diagnosis of intracranial lesions by computerised transverse axial scanning.

The diagnostic accuracy of computerised transverse axial tomography in conjunction with enhancement of tissue density by sodium iothalamate was assessed in 438 patients, 256 of them having intracranial tumours and 182 having other intracranial disorders. THE 80 X 80 matrix and 20 ml intravenous sodium iothalamate were used in 174 patients, the 160 X 160 matrix and 20 ml sodium iothalamate in 126 patients, and the 160 X 160 matrix and 60 ml sodium iothalamate in 138 patients. The diagnostic accuracy rose from 87% in the first group to 100% in the final group. The proportion of patients showing enhancement of tumour tissue density improved from 64% in the first group to 96% in the third. In the non-tumour patients, excluding those in whom the underlying disease caused no alteration of brain structure or tissue density, the overall accuracy was 96%, being unaffected by the modifications of technique. The enhancement of tissue density in brain abscesses, some cerebral infarcts, and angiomas could be readily distinguished from that seen in tumours.

Astrocytoma↗
PubMed1975

Computerized axial tomography in the detection of orbital space-occupying lesions.

Of 41 patients we examined for a suspected primary orbital tumor, 25 patients had evidence of a lesion either histologically, angiographically, or surgically. We examined nine of the 25 patients by means of an EMI-Scanner and 16 by a fine matrix addition (160 times 160 cells), and compared these results to those we received by axial tomography, orbital venography, and B-scan ultrasound. We also compared the absorption values of the recorded tumors. The EMI-Scanner had a diagnostic accuracy of 84%; orbital venography, 84%; axial hypocycloidal tomography, 71%; and ultrasound, 76%. The fine matrix scanner gave a preoperative diagnostic rate of 93% and defined optic nerve abnormalities accurately. However, EMI, scanning should complement existing noninvasive procedures and orbital venography.

Adolescent↗
PubMed1975

An assessment of the accuracy of computerized transverse axial scanning (EMI scanner) in the diagnosis of intracranial tumour. A review of 366 patients.

The computerized transverse axial (CTA) scans of 366 patients with intracranial tumours and 267 patients without tumours, but with similar presenting features, were analyzed. In all cases the definitive diagnosis was established either by histological or neurological methods. Most tumours were found to be of low tissue density, but a gradation from low through normal to a high density appearance was recognized. Tissue density enhancement with sodium iothalamate was achieved in 63-9% of supratentorial and 62-4% of infratentorial tumours, and usually allowed a more accurate determination to be made of the boundary between the tumour and the surrounding oedema. The accuracy of the CTA scanner as a screening technique was found to be 96%, this being superior to either clinical evaluation or rectilinear isotope scanning. When assessed on the basis of structural abnormalities demonstrated in the same groups of patients, the CTA scans enabled a diagnosis to be made or a lesion excluded in 92-3% of the patients, a figure which bears comparison with arteriography and pneumo-encephalography. It is anticipated that the simplicity and superior sensitivity of the system should decrease the necessity for invasive techniques such as angiography and pneumo-encephalography in the future.

Adenoma↗