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Biomedical subjects

I Hutton

Publications and source records attributed to I Hutton.

At least 19 recordsLinked to original sources
PubMed1992

A comparison of maximal exercise and dipyridamole thallium-201 planar gated scintigraphy.

Both symptom-limited maximal exercise and intravenously given dipyridamole stress (0.56 mg/kg over 4 min with a 2 min walk) gated thallium scans were performed in 22 patients undergoing coronary arteriography for the assessment of chest pain. All scans were acquired gated to the electrocardiogram in 3 projections and were reported for the presence and extent of defects in 5 myocardial segments in each view. In addition, left and right ventricular myocardial uptake and estimates of right and left lung and liver to left ventricular uptake were assessed relative to the injected dose of thallium-201. Overall, 190/310 segments were abnormal with exercise compared with 169/310 with dipyridamole. Segments were scored greater in extent in 90/310 cases with exercise, compared with 46/310 in which the defect was more extensive with dipyridamole (P less than 0.0005). Non-attenuation corrected percentage myocardial thallium uptakes were similar for both stresses: anterior percentage uptakes, 0.785% +/- 0.230% with exercise versus 0.870% +/- 0.217% with dipyridamole (NSD). Left and right lung and liver to left ventricle ratios were all significantly higher with dipyridamole than with exercise (1.587 +/- 0.408 versus 1.446 +/- 0.518, P less than 0.02; 1.78 +/- 0.479 versus 1.46 +/- 0.502, P less than 0.002; 2.598 +/- 0.788 versus 1.265 +/- 0.386, P less than 0.001, respectively). High right and left lung uptakes with dipyridamole were strongly correlated with high exercise values (r = 0.756, P less than 0.001; r = 0.809, P less than 0.001). The liver uptake was weakly correlated between the 2 different stress tests (r = 0.483, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Coronary venous lipid peroxide concentrations after coronary angioplasty: correlation with biochemical and electrocardiographic evidence of myocardial ischaemia.

BACKGROUND: Raised lipid peroxide concentrations in coronary venous plasma have been reported after coronary angioplasty in humans. This may reflect increased free radical activity after myocardial ischaemia and reperfusion. If so, it may be possible to correlate lipid peroxide concentrations with the degree of myocardial ischaemia produced during angioplasty. METHODS: 15 patients (age range 42-70; 12 men) with stable angina pectoris undergoing angioplasty of a proximal left anterior descending coronary artery stenosis were studied. Plasma lipid peroxide and lactate concentrations were measured in sequential blood samples taken from the great cardiac vein before and immediately after one to five serial 60 second balloon inflations. The maximum ST segment shift during each balloon inflation was also measured. RESULTS: Lipid peroxide concentrations in coronary venous plasma were raised from pre-angioplasty values by more than 2 SDs of the relevant measurement error after 27 out of 46 (59%) balloon inflations. Lactate concentrations were raised after 43 out of 46 (93%) balloon inflations. No significant difference was found between the peak percentage change of either lipid peroxide or lactate concentrations after any of the first three serial inflations. The maximum ST segment shift after each of the first three serial inflations was also similar. Coronary venous lactate concentrations after balloon inflation correlated positively with the maximum ST segment shift, but did not correlate with lipid peroxide concentrations. CONCLUSIONS: Raised lipid peroxide concentrations in coronary venous plasma can be detected in humans after balloon angioplasty. There is no positive correlation between lipid peroxide concentrations in coronary venous plasma after angioplasty and the degree of preceding myocardial ischaemia as assessed by either ST segment shift or lactate production. These indices showed that one to three serial 60 second balloon inflations each produce a similar degree of myocardial ischaemia. The origin of the raised lipid peroxide concentrations in coronary venous plasma after angioplasty remains unknown.

Adult↗
PubMed1992

Thallium scans in syndrome X.

OBJECTIVE: To review thallium scans in patients with angina and normal coronary arteriograms. DESIGN: Retrospective review of data. SETTING: Regional cardiac centre in Glasgow. PATIENTS: 100 patients selected from those undergoing diagnostic angiography for typical angina who had normal arteriograms (around 10%), no other cardiovascular abnormality, and available thallium scans (performed routinely before angiography). MAIN OUTCOME MEASURES: Coronary arteriography, exercise tests, and gated thallium scans at peak exercise. RESULTS: The exercise test was positive in 30 and negative in 70 patients. Thallium defects were found in 98 patients, but no consistent pattern and no significant correlation existed between the extent of thallium defect and positive exercise test or exercise tolerance. CONCLUSIONS: Thallium defects described in 98 of 100 patients with angina and normal coronary arteriograms suggest that microvascular angina may be commoner than is generally appreciated.

Adult↗
PubMed1992

Balanced triple-vessel disease: enhanced detection by estimated myocardial thallium uptake.

Maximal stress thallium scans may prove to be 'normal' in some patients with triple-vessel disease due to global reduction in flow resulting in no focal perfusion defect. The aim of this study was to attempt to identify patients with global reduction in flow by estimating total thallium delivery to the left ventricle. Myocardial thallium uptake was calculated as a percentage of injected dose as a mean of three projections in 90 patients undergoing diagnostic arteriography and in 10 normal volunteers. These volunteers and nine patients who proved to have normal coronary arteries established a normal range. Values for myocardial thallium uptake were: 1.166 +/- 0.352% in normals (n = 19); 0.671 +/- 0.184% in patients with single- or double-vessel disease (n = 26); 0.708 +/- 0.245% in patients with triple-vessel disease (n = 55). Thallium scans were normal in 11 of 55 patients with triple-vessel disease and eight of 26 with single- or double-vessel disease. However, eight of these 11 and 5 of the eight proved to have abnormal myocardial thallium uptake. Thus combining the tests improved sensitivity from 76.5% for the scan alone to 94.5% for the scan and myocardial thallium uptake, with no reduction in specificity. Measurement of myocardial thallium uptake is a readily and reliably quantified parameter from a thallium scan which leads to enhanced detection of coronary artery disease.

Adult↗
PubMed1991

Acute and chronic effects of once-daily isosorbide-5-mononitrate on the exercise capacity of patients with angina pectoris treated with a beta-blocking drug.

Forty-four patients with stable effort angina pectoris were included in a double-blind, randomised, placebo-controlled, parallel group study to compare the effect of two slow-release forms of isosorbide-5-mononitrate ('Ismo-Retard' 40 mg and 'Imdur' 60 mg) on exercise capacity when given as an adjunctive treatment to beta adrenoreceptor blocking therapy. In a symptom-limited exercise test performed three hours after the first dose, Ismo-retard increased the total duration of exercise by 92 seconds (confidence interval (CI) 5.1-116.9) p less than 0.006, and the time of onset to anginal pain by 117 seconds (CI 27.8, 156.1) p less than 0.004. A similar improvement in total duration of exercise (by 87 seconds) was noted three hours following 15 consecutive once-daily doses (CI 16.8-128) p less than 0.02, and in the time of onset to anginal pain by 101 seconds (CI 19.8-139.6) p less than 0.01. For Imdur the corresponding results were 53 seconds (CI 12.7-56.3), 84 seconds (CI 15.4-103.7), p less than .02, 54 seconds (CI 1.4-78.4) and 85 seconds (CI 6.9-120.5) respectively. These results would suggest that both active treatments were effective anti-anginal agents.

Adrenergic beta-Antagonists↗
PubMed1990

Quantification of aortic regurgitation using continuous and pulsed wave Doppler echocardiography.

In a prospective blind study, continuous and pulsed wave Doppler echocardiography were used to predict the severity of angiographically assessed aortic regurgitation in 36 patients. High quality continuous wave spectral recordings of the regurgitant jet were obtained in 32 patients but four patients with mild aortic regurgitation had dropout of high velocity signals precluding accurate assessment. The deceleration slope of the peak to end-diastolic velocity measured by continuous wave Doppler, and pulsed wave Doppler mapping of the regurgitant jet in the left ventricle were compared with angiographic severity. The deceleration slope was significantly steeper in patients with severe rather than mild or moderate aortic regurgitation (3.65 +/- 1.04 vs. 1.89 +/- 0.42 vs. 1.52 +/- 0.59 m sec-2). A decay slope of greater than 3 m sec-2 was observed only in patients with 3+ or 4+ aortic regurgitation and a decay slope less than 1.2 m sec-2 was seen only in mild 1+ aortic regurgitation but there was considerable overlap between groups, making it difficult in individual cases to assess severity on the basis of the continuous wave deceleration slope. The pulsed wave Doppler technique was more time consuming, added little to the continuous wave Doppler assessment and underestimated severe regurgitation in almost 50% of cases. Hence, there are significant problems using either Doppler technique in quantitatively assessing aortic regurgitation.

Adolescent↗
PubMed1990

Doppler echocardiographic characteristics of normal and dysfunctioning prosthetic valves in the tricuspid and mitral position.

The Doppler echocardiographic characteristics of 70 prosthetic valves in 35 patients are reported. Twenty nine patients had a Björk-Shiley prosthesis in both mitral and tricuspid positions and six had Carpentier-Edwards valves in both sites. Five of the patients had abnormal tricuspid prostheses on the basis of clinical and echocardiographic criteria. Pulsed wave Doppler echocardiography was used in all examinations. The pressure half times for the normal tricuspid prosthetic valves, 105 (40) ms (Björk-Shiley) and 97 (53) ms (Carpentier-Edwards), were significantly longer than those of normal mitral prosthetic valves, 75 (18) ms (Björk-Shiley) and 83 (15) ms (Carpentier-Edwards). The range of pressure half times for the abnormal tricuspid valves (237-530 ms) was distinct from that of the apparently normal tricuspid prosthetic valves (38-197 ms). There was an increase in the peak velocity of the obstructed tricuspid prosthetic valves (1.69 (0.12) m/s) in comparison with normal prostheses (1.06 (0.26) m/s). The normal range of pressure half times for the Björk-Shiley and Carpentier-Edwards valves in the mitral position is not applicable to the same valves in the tricuspid position. The valve appears to function well with very long pressure half times but a pressure half time of greater than 200 ms coupled with a peak velocity of greater than 1.60 ms without significant valve regurgitation indicates tricuspid obstruction of the tricuspid prosthetic valve.

Adult↗
PubMed1989

Improved detection of coronary artery disease by estimated myocardial thallium uptake.

Myocardial thallium uptake has been assessed at the time of thallium scanning in a group of 50 male patients undergoing coronary arteriography and 10 young healthy volunteers. The net thallium dose injected was obtained by counting the dose prior to injection using the gamma camera and counting the syringe and IV cannula after injection. Significantly higher levels of myocardial thallium uptake were obtained in both the volunteers and patients with normal coronary anatomy (1.36% +/- 0.32%, n = 10 and 0.93% +/- 0.26%, n = 9, respectively) compared to patients with single, double or triple vessel coronary artery disease (0.63% +/- 0.19%, n = 11; 0.70% +/- 0.20%, n = 15; 0.67 +/- 0.18, n = 15, respectively). Exercise tests were positive in 46% of patients with coronary artery disease with an overall predictive accuracy of 56%. Thallium scans were positive in 68% of patients at a specificity of 89%. If the range of myocardial thallium uptake from the patients with normal coronary arteries is used to define a lower limit of normal, then the sensitivity of the thallium scan with thallium uptake is 90% with a predictive accuracy of 90% in the detection of significant coronary artery disease in this group of patients. Thus, estimation of total % thallium uptake is a simple index which yields useful diagnostic clinical information.

Adult↗
PubMed1989

Assessment of right ventricular function in acute inferior myocardial infarction using 133-xenon imaging.

UNLABELLED: The detection of right ventricular dysfunction in acute inferior myocardial infarction is important because of its potentially serious consequences which may be remediable with the appropriate therapeutic manoeuvres. A technique has been developed to assess right ventricular function using 133-xenon. This technique was applied to 26 patients who had sustained an acute inferior myocardial infarction. Right ventricular ejection fractions ranged from 7-54%, mean 30 +/- 11%, which was significantly lower than values obtained from normal volunteers (n = 21), mean 43 +/- 5%, and patients with arteriographically proven coronary artery disease without previous myocardial infarction (n = 12), mean 39 +/- 9%, P less than 0.001, and P less than 0.001, respectively. In the patients with acute inferior myocardial infarction 18 patients (69%) had evidence of right ventricular dysfunction (right ventricular ejection fraction less than 35%). 13/26 patients (50%) had clinical evidence of right ventricular dysfunction with a mean right ventricular ejection fraction 26 +/- 11% (range 7-54%) which was significantly lower than the patients without evidence of right ventricular dysfunction, mean 35 +/- 9% (range 16-49%), P less than 0.001. The clinical signs had a sensitivity of 72% (13/18), a specificity of 87.5% (7/8) and a predictive accuracy of 76% (20/26) when compared to the imaging data. IN CONCLUSION: (1) gated 133-xenon imaging provides a method for assessing right ventricular function in the setting of acute myocardial infarction; (2) a wide spectrum of right ventricular dysfunction occurs following inferior myocardial infarction which may not manifest itself clinically.

Adult↗
PubMed1989

Long term haemodynamic, pulmonary function and symptomatic effects of pirbuterol in COPD.

Haemodynamic studies at rest and during exercise together with radionuclide ventriculography, pulmonary function and clinical well-being assessment were evaluated in ten patients with COPD and secondary pulmonary hypertension (mean PAP 25 mm Hg), before and after 6 months therapy with pirbuterol 20 mg thrice daily. Despite the continued pharmacological action of pirbuterol on the heart and systemic circulation during peak pirbuterol levels at 6 months, no significant effect on the pulmonary circulation was observed. Seven patients reported an improvement in the level of fatigue, the partial pressure of carbon dioxide fell significantly (6.5 +/- 0.9 to 6.1 +/- 0.9 kPa: P less than 0.01) and there was a slight bronchodilator effect [forced expiratory volume in 1s (FEV1) 0.60 +/- 0.18 to 0.71 +/- 0.2 1s-1: P less than 0.02] after 6 months. The drug was generally well tolerated but three patients with pre-existing biliary tract disease developed obstructive jaundice.

Aged↗
PubMed1989

An automated analysis technique for thallium images.

The use of stress thallium-201 scans in the non-invasive assessment of myocardial perfusion is well established, despite several reports of considerable inter-observer variability in the assessment of perfusion defects. By applying a simple statistical algorithm to a set of normal thallium images and using a well defined criterion of abnormality, the threshold of normality in these 'statistical images' was obtained for each of four projections. Subsequently a test set of images from both normal volunteers and patients with arteriographically documented coronary artery disease were reported using statistical images at four levels (70, 75, 80 and 85% of the mean of the hottest pixels) and standard thallium images viewed on the computer monitor in both colour and black and white. Significant reductions in the inter-observer disagreement and enhanced predictive accuracy in the detection of significant coronary artery disease were obtained using the statistical images. The technique described and assessed would permit the reporting of thallium scans at a preselected value of sensitivity and specificity depending on the requirements of the particular study. It could be readily implemented, after local validation, in any department performing thallium scans where the gamma camera is interfaced to a computer.

Adult↗
PubMed1989

Perfusion imaging.

The term perfusion has varied connotations in different situations. The word perfusion comes from the Latin to pour or diffuse through or over. Myocardial perfusion depends on (a) coronary artery or vessel flow, and (b) myocardial or muscle flow. The factors which determine perfusion at rest and during stress in coronary vessels and within the myocardium are clearly related but not with a predictable linear relationship. In animals there is extensive literature concerning the regulation of coronary flow and perfusion obtained by many sophisticated methods. In contrast, the techniques that are applicable to humans are relatively crude. To date, the clinical data available suggests that the normal control of coronary flow in man and in dogs is fairly similar but that models of pathology in animals bear little relation to the compensatory changes found in the coronary circulation in man. Although the data available is limited and subject to many technical inaccuracies, this article is confined to the assessment of myocardial perfusion in clinical practice.

Coronary Circulation↗
PubMed1989

The evaluation of right ventricular function in acute myocardial infarction by xenon-133.

Right ventricular performance was assessed in 37 patients with acute myocardial infarction within two hours of admission to Coronary Care and compared to results in 21 normal volunteers and 12 patients undergoing coronary arteriography. Right ventricular ejection fraction (RVEF) was measured from gated xenon-133 scans. The normal range of RVEF (42.8 +/- 5.1%) was significantly higher than in the 30 patients with inferior infarction (26.3 +/- 10.9%; p less than 0.001) and was similar to that in patients with anterior infarct (40.6 +/- 5.4%; ns) and patients undergoing coronary arteriography (39.3 +/- 4.9%; ns). Fifteen of the patients with inferior infarct had clinical evidence of right ventricular dysfunction with a mean RVEF of 18.9 +/- 7.9%, significantly below the fifteen patients with no clinical evidence of right ventricular dysfunction (34.3 +/- 8.3%; p less than 0.001).

Adult↗
PubMed1988

Sustained haemodynamic effects of felodipine in patients with chronic cardiac failure.

1. The efficacy of felodipine a new calcium channel blocker with selective vasodilator activity in the management of severe low output cardiac failure, secondary to coronary heart disease, was determined in 10 patients. 2. Haemodynamic measurements were made at rest and during dynamic exercise and left ventricular function was assessed by radionuclide ventriculography. 3. Significant increases in cardiac index, stroke volume index and ejection fraction were found particularly during exercise, both acutely and following 4 weeks administration of felodipine therapy. 4. Felodipine could well have a significant role in the long term management of the patient with chronic cardiac failure.

Adult↗