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Biomedical subjects

T Hawkins

Publications and source records attributed to T Hawkins.

At least 55 records · Page 3Linked to original sources
PubMed1990

Reduction in ST segment elevation after thrombolysis predicts either coronary reperfusion or preservation of left ventricular function.

The usefulness of a reduction in ST segment elevation to predict coronary reperfusion in myocardial infarction remains uncertain. ST segment changes and angiographic findings were compared in 45 patients soon after thrombolysis. The percentage ST segment change 3 hours after treatment (in the lead showing the greatest initial ST elevation) was compared with the TIMI perfusion grade (thrombolysis in myocardial infarction trial) obtained between 90 minutes and 3 hours after treatment. Global ejection fraction and regional wall motion were assessed by cineventriculography (11 (5) days (mean (SD))) and by gated blood pool imaging (44 (11) days). Prediction of coronary patency by a reduction of greater than 25% in ST segment elevation 3 hours after thrombolytic treatment had a sensitivity of 97% but a specificity of only 43%. Where the ST segment elevation was reduced by greater than 25% the global ejection fraction was well maintained whether or not the infarct vessel was patent. In patients with a reduction of less than 25% in ST elevation, the ejection fraction was significantly lower and regional wall motion abnormality more severe. Reduction in ST elevation of greater than 25% within 3 hours of thrombolysis indicates either a patent infarct artery or preservation of left ventricular function. When the ST segment elevation does not fall by greater than 25% persistent coronary occlusion is likely (predictive accuracy 86%) and is associated with a lower ejection fraction. These patients may benefit from further treatment or additional interventions.

Adult↗
PubMed1990

Dipyridamole echocardiography: the bedside stress test for coronary artery disease.

Identification of dipyridamole-induced regional wall motion abnormalities by echocardiography has recently been proposed as an alternative diagnostic stress test for coronary artery disease. This study evaluates this new technique by comparing the results obtained (overall, regionally and by abnormality type) with those of thallium-201 myocardial imaging after dipyridamole stress in 25 patients. Acceptable echocardiograms were obtained in 20 patients (80%). Concordance of echocardiographic abnormalities for both overall and regional thallium abnormalities was 85%. Sensitivity, specificity and predictive value of dipyridamole echocardiography for overall and regional thallium defects were 92%, 71% and 85%, and 91%, 81% and 85% respectively. However, concordance between the two for abnormality type (i.e. ischaemia versus infarction) was only 66% and the sensitivity, specificity and predictive value of dipyridamole echocardiography for identifying ischaemia as opposed to infarction were only 43%, 82% and 63%, respectively. There was substantial agreement between thallium and echocardiographic imaging after dipyridamole infusion in the diagnosis of coronary artery disease. Echocardiography appears less well able to distinguish infarction from active ischaemia. Dipyridamole echocardiography provides a highly versatile, noninvasive bedside stress test for the detection and localization of coronary artery disease.

Adult↗
PubMed1989

A comparison of myocardial thallium-201 image quality after either dipyridamole or exercise stress.

Exercise and dipyridamole provide two mechanistically different stress techniques for thallium-201 imaging. To date, comparisons of the two have relied solely on assessments of clinical results. However, because diagnostic accuracy ultimately depends on image quality, this study was undertaken to compare the image quality obtained by both techniques. The left anterior oblique images of 30 patients, who had thallium imaging after intravenous dipyridamole (0.56 mg kg-1 over 4 min) were compared with those of 30 patients who were imaged after symptom limited, Bruce protocol, treadmill exercise in the same time period. Myocardial and lung-background thallium uptake were compared after stress and on redistribution. The ratio of the best segmental myocardial thallium uptake (M) to that in a fixed lung-background region (B) was taken as an index (M/B) of image quality. Myocardial thallium uptake was significantly higher after dipyridamole than after exercise (P less than 0.001). Lung-background thallium uptake, however, was also higher (P less than 0.001) so that the resulting image quality indices (M/B) were similar (P = NS). The redistribution images gave the same results. In both techniques myocardial and lung-background thallium uptake counts dropped significantly from stress to redistribution images, but because they declined at similar rates, the resulting image quality index (M/B) remained unchanged. Adverse effects occurred less frequently in the dipyridamole stressed group. Thallium images performed after dipyridamole stress are at least equivalent in image quality to those after exercise stress. This technical study further strengthens the clinical case for the use of the dipyridamole stress technique in routine diagnostic imaging.

Dipyridamole↗
PubMed1988

AIDS: knowledge and attitudes in Otago.

A postal questionnaire was sent to 307 people, during July 1987. The questionnaire examined public knowledge, attitudes and strategies for education for future planning by the Southern Region Health Services Association. According to the age group those respondents aged 45-59 years scored best in the knowledge section. The younger ages (18-29) years and 30-44 years scored closely, while the elderly scored least. However, more than 10% of respondents were incorrect in their answers concerning the most basic questions, and an even larger number were unsure about casual contact as a method of AIDS virus transmission. Many people did not realise all blood donations in New Zealand were screened for AIDS virus. Attitudes reflected current controversy concerning the availability of free needles and condoms. Fifty five percent of respondents were definitely in favour of compulsory blood testing even though the question did not specify which groups of people might be tested. The vast majority made a strong plea for more information about AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Neuroleptic malignant syndrome: a review of the Wellington experience.

The neuroleptic malignant syndrome is a potentially lethal complication of central dopamine antagonism. We report five cases, occurring in the Wellington region in the last 4 years. Three of the cases are reported in detail and the diagnostic difficulties and therapeutic strategies are reviewed. Particular attention is drawn to the use of the depot intramuscular phenothiazine formulations which were clearly implicated in our experience.

Adult↗
PubMed1988

An evaluation of technetium-99m tin colloid--its value in the diagnosis of renal transplant rejection.

The value of the Technetium-99m tin colloid (TTC) scan in the diagnosis of renal transplant rejection occurring more than 1 month following transplantation was assessed. To our knowledge, use of this agent has not previously been reported. Gamma camera imaging was performed on 15 occasions in 14 patients in whom plasma creatinine was rising and in three patients in whom renal function was stable. Both a qualitative and a quantitative assessment of images was made. The radioactivity recorded over the graft at 12-16 min post injection was expressed as a percentage of that recorded at 0-4 min. In the nine patients in whom graft perfusion was adequate to allow interpretation of the TTC scan and in whom rejection was diagnosed by biopsy (six cases) or on clinical grounds (three cases), the index ranged from 45 to 153%. In two patients the graft was poorly perfused and the accumulation of TTC was predictably low despite the presence of rejection. In the seven patients with either a stable creatinine or with rising creatinine not due to rejection, the index ranged from 5 to 43%. Previously reported studies have shown that sulphur colloids may be of value in diagnosing graft rejection. This study suggests that Tc99m tin colloid may be regarded as a suitable alternative scanning agent and that some simplification of data collection and analysis can be achieved.

Colloids↗
PubMed1987

Use of radionuclide scanning in the preoperative estimation of pulmonary function after pneumonectomy.

Twenty eight patients with bronchial carcinoma were studied before pneumonectomy. Measurement of spirometric indices, static lung volumes, transfer factor (TLCO), and transfer coefficient (KCO) was undertaken before and four months after pneumonectomy. Fourteen of the patients also performed a symptom limited progressive exercise test on a cycle ergometer before and four months after pneumonectomy. All patients had standard xenon-133 ventilation and technetium-99m perfusion scans performed before operation. Eleven patients had krypton-81m ventilation scans in addition. Significant correlations were seen between changes in FEV1, TLCO and KCO and the preoperative function of the resected lung as determined by percentage preoperative perfusion to that lung (p less than 0.001). There were mean decreases in FEV1 of 22% and in vital capacity (VC) of 28.7% predicted. Estimation of postoperative FEV1 from the preoperative values showed equally good agreement with measured postoperative values whether 99mTc perfusion or 81mKr ventilation scans were used in the 11 patients in whom both scans were available. Significant correlations were seen between change in maximum exercise ventilation (VEmax) or maximum oxygen uptake (VO2max) after pneumonectomy and percentage preoperative perfusion to the resected lung (p less than 0.001). Estimation of postoperative maximum ventilation and maximum oxygen uptake from the postoperative values on the basis of 99mTc perfusion scans showed good agreement with observed values. Perfusion scans are useful in estimating not only the changes in spirometric indices that follow pneumonectomy for bronchial carcinoma but also changes in carbon monoxide transfer and exercise capacity.

Adult↗
PubMed1985

The role of the ileal conduit in the development of upper tract dilatation.

The purpose of this study was to clarify the role of the conduit in the development of upper tract dilatation after ileal conduit urinary diversion. Twenty-seven patients with a normal upper tract were compared with 17 who had developed upper tract dilatation. Patients were studied by means of a technique to measure pressure and flow under "steady-state" conditions. Pressure activity was classified into two types. Type I pressure activity (frequency 6.2 +/- 3/min; amplitude 4.7 +/- 3 cm H2O) resulted in to-and-fro movement of contrast and the escape into the appliance of small volumes of contrast. In controls, most of the output from the conduit occurred during type I activity (73 +/- 14%). Type III/IV pressure activity resulted in vigorous aboral peristalsis and occurred infrequently in controls (frequency 5 +/- 4/h). In patients with upper tract dilatation, in contrast, type III/IV peristaltic activity occurred frequently (frequency 37 +/- 30/h; P less than 0.001: amplitude 72 +/- 34 cm H2O) and was responsible for most of the output (70 +/- 17%; P less than 0.001). The findings support the hypothesis that high pressure activity in the conduit is an important factor in the aetiology of upper tract dilatation, and they are compatible with the presence in such patients of functionally important obstructions of the distal conduit.

Dilatation, Pathologic↗
PubMed1984

Role of exercise testing early after myocardial infarction in identifying candidates for coronary surgery.

It has been suggested that ST depression in lead V5 or equivalent on early exercise testing after acute myocardial infarction predicts a high risk of death. To evaluate exercise testing and radionuclide ventriculography in this context 103 consecutive patients with myocardial infarction who were able to undertake a limited exercise test before discharge from hospital were exercised and underwent gated blood pool scanning. No serious complications resulted from exercise testing. Twenty nine patients developed ST depression in lead V5, 19 had exertional hypotension, 31 developed a heart rate of greater than or equal to 130 beats/min, and 15 had complex ventricular arrhythmias. Death during the first year after discharge from hospital was associated with exertional hypotension (p less than 0.001) and a heart rate on exercise testing of greater than or equal to 130 beats/min (p less than 0.05); these two variables identified all nine deaths. Inability to complete the exercise protocol for any reason was also predictive of death (p less than 0.01). Ventricular arrhythmias and ST depression in lead V5 induced by exercise were not significantly associated with an increased risk of death. The mean (SD) radionuclide ejection fraction in the patients who died was 29 (16%) compared with 43 (11)% in the patients who survived (p less than 0.001). ST changes on exercise testing after myocardial infarction appear to be less predictive of later complications than haemodynamic signs, which may indicate left ventricular damage rather than ischaemia.

Adult↗