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I Hutton

Publications and source records attributed to I Hutton.

At least 19 recordsLinked to original sources
PubMed1998

Lung uptake of thallium-201: a marker of defect reversibility?

High lung uptake of thallium-201 at stress is reported to be associated with a large number of perfusion defects and poor prognosis. This study was performed to assess whether the reversibility of stress perfusion defects was related to lung uptake. Gated planar thallium scans at stress and at redistribution from 102 consecutive patients with essentially normal left ventricular ejection fraction (using 99mTc gated blood pool ventriculography) were graded in terms of defect size. Lung and myocardial uptake of thallium were quantitated by region of interest methods relative to the given activity in a previously validated method. There was no significant correlation (non-parametric) between lung uptake and degree of redistribution (p = ns, rs = 0.140). There was a weak but positive correlation between lung uptake and defect size (p < 0.05, rs = 0.188). Both exercise time and double product showed a negative correlation with lung uptake (e.g. for double product, p < 0.0005, rs = -0.541). In conclusion, contrary to our expectation, lung uptake is not related to the degree of redistribution. High lung uptake seems to reflect poor cardiovascular reserve.

Biophysical Phenomena↗
PubMed1998

Single crystal biplane equilibrium radionuclide ventriculography: an improved planar imaging technique.

Radionuclide ventriculography in the best septal view is an established method to assess both global and regional ventricular function. Additional projections may be used to delineate the wall motion of inferior myocardial segments. Radionuclide ventriculography was performed in 65 patients using both a single plane (in the best septal view) and a biplane technique. The biplane collimator allowed simultaneous assessment in two planes 40 degrees apart, allowing simultaneous visualization of all four myocardial walls. Seventeen patients with regional wall motion abnormalities were detected with the single plane best septal view and a further 18 patients with impaired wall motion were identified with the biplane collimator (51% of the abnormal ventricles). The additional abnormal segments were seen in only the steep lateral projection. Left ventricular ejection fraction estimation with the biplane technique remains highly reproducible and correlates well with that derived from the best septal view. Biplane radionuclide ventriculography improves the detection of inferior wall motion abnormalities at no expense of time, and offers the possibility of performing two-view stress ventriculography with inotropic agents.

Coronary Artery Bypass↗
PubMed1996

Small artery structural alterations of patients with microvascular angina (syndrome X).

1. There is increasing evidence that a substantial number of patients who suffer from angina have normal epicardial arteries (Syndrome X), and it has been suggested that these individuals have a generalized disorder of small vessels not confined to the intramyocardial vasculature. 2. Small arteries were therefore obtained from biopsies of skin and subcutaneous fat from nine normotensive patients with Syndrome X and nine matched control subjects. Vessels were dissected and mounted as ring preparations in a myograph for morphological and functional assessment. 3. Morphological measurements revealed a significant increase in media thickness/lumen diameter ratio in arteries from patients with Syndrome X. Contractile responses to U46619 were similar in arteries from patients and control subjects. Endothelium-dependent relaxation induced with acetylcholine and bradykinin was greater in arteries from patients although differences were not statistically significant. Endothelium-independent relaxation induced by forskolin and sodium nitroprusside was not different. 4. In conclusion, these data demonstrate that subcutaneous small arteries from patients with Syndrome X are characterized by increased media thickness/lumen diameter ratios, although contractile responses were normal. Additionally, endothelium-dependent relaxation was not impaired in arteries from these patients. Thus, no significant functional abnormalities were associated with the observed structural differences.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Exercise 201Tl/rest 99Tcm-tetrofosmin myocardial perfusion imaging: a convenient protocol for the assessment of coronary disease.

Standard exercise thallium-201 (201Tl)-redistribution protocols for the detection of coronary artery disease take about 4 h to complete. This is inconvenient for both patients and staff. The higher energy technetium-99m (99Tcm) emissions permit immediate imaging after 201Tl with minimal crosstalk. This study assessed exercise gated planar 201Tl scintigraphy (55 MBq) followed by rest gated planar 99Tcm-tetrofosmin scintigraphy (250 MBq) in 32 patients. The results showed a high sensitivity for the detection of coronary disease (100%) in this highly selective group of patients. In order to diagnose myocardial infarction accurately, it was necessary to view the gated 201Tl images and assess regional wall motion in a defect zone. This gave a specificity of 88% and a sensitivity of 71% for the prediction of myocardial infarction on the angiographic ventriculogram. Stress 201Tl/rest 99Tcm-tetrofosmin is a useful short protocol for patients unable to complete the full 4-h exercise 201Tl-redistribution study.

Adult↗
PubMed1996

Rest or redistribution thallium myocardial imaging for resting myocardial perfusion: a detailed comparison with regional wall motion.

Redistribution thallium-201 (201T1) imaging is the most common method of assessing resting myocardial perfusion. However, the equivalence of a redistribution image and a separate rest injection is unclear. Although the presence of a defect on rest imaging has normally been equated with the presence of a myocardial infarction, it has recently been shown that a significant proportion of fixed defects on exercise-redistribution 201T1 actually represent areas of viable myocardium. This study was a detailed comparison of rest and redistribution imaging in 30 patients undergoing routine exercise 201T1 scanning for the assessment of coronary artery disease. A small dose (15 MBq) of 201T1 was administered at rest following the imaging in three standard planar views. Similar stress images were acquired using a further 50-55 MBq of 201T1 administered at peak effort. Redistribution images were acquired 3-4 h later and equilibrium blood pool ventriculography performed using in vivo labelling with 600 MBq 99Tcm-pertechnetate. Of 150 abnormal segments on the exercise scans, 74 (49%) were identified as being reversible on the redistribution scans and 58 (39%) on the rest images. Only 39 (53%) of these reversible defects were identified on both the redistribution and rest scans. Only 41% of the fixed defects on the redistribution images (32% of fixed defects on the rest images) had abnormal wall motion. Therefore, rest and redistribution images are not equivalent. Both rest and redistribution images significantly overestimate myocardial infarction. This may have significant effects on patient selection for revascularization procedures and therefore all patients having perfusion scintigraphy should also have additional assessment of regional wall motion to allow accurate classification of the functional status of myocardial segments.

Coronary Circulation↗
PubMed1996

Planning for coronary angioplasty: guidelines for training and continuing competence. British Cardiac Society (BCS) and British Cardiovascular Intervention Society (BCIS) working group on interventional cardiology.

The following recommendations are made: 1 Existing centres undertaking angioplasty should increase their activity, and the target figure of 400 PTCA procedures per million of the United Kingdom population should be achieved by the end of 1996-97, or immediately thereafter. 2 Angioplasty centres should be appropriately equipped to undertake PTCA safely and effectively and provide a reliable emergency service. They should have a minimum of two trained PTCA operators jointly undertaking a minimum of 200 procedures per year at that centre, and have regular meetings to share experience. 3 Angioplasty operators should ensure that where the need arises patients undergoing PTCA can receive immediate attention from a trained operator at any time until discharge from hospital. 4 Trained operators should undertake at least 1-2 PTCA procedures per week (> 60 procedures per year) to maintain competence, and those undertaking so few procedures should increase their activity over the next three years to more than 100 a year. 5 Trainers should have performed at least 500 procedures before formally training others and should undertake a minimum of 125 procedures a year to maintain accreditation as a trainer. 6 Surgical cover for PTCA procedures should be mandatory and on site cover remains the strongly preferred option. Where surgical cover is provided off site, this should be at a centre less than 30 minutes away by road. Whether provided on or off-site it should be possible to establish cardiopulmonary bypass within 90 minutes of the decision being made to refer the patient for surgery. 7 All operators and interventional centres should audit their activity and results, review these data locally with colleagues, and provide regular audit returns to the national database run by BCIS. This will allow future recommendations concerning standards to take more account of risk stratification and actual outcomes, and not place such emphasis merely on volumes of activity. 8 These recommendations should be reviewed in three years.

Angioplasty, Balloon, Coronary↗
PubMed1994

A clinical and in vitro study on the possible interaction of intravenous nitrates with heparin anticoagulation.

It has been reported that intravenous nitrates inhibit the anticoagulant effect of heparin. This possible interaction has potentially serious implications for the management of patients with acute coronary ischemic syndromes. This possible interaction was assessed prospectively in a clinical and in an in vitro study involving 24 patients receiving both drugs for the management of unstable angina pectoris. There was a small inhibitory effect of intravenous glyceryl trinitrate or isosorbide dinitrate on the anticoagulant effect of heparin in 3 of 24 cases in vivo, as assessed by activated partial thromboplastin time measurements. Nitrates or propylene glycol had no effect on heparin activity in vitro. It was concluded that there may be an inhibitory effect of nitrates on anticoagulation in a small minority of patients, but close attention to detail in monitoring heparin anticoagulation is far more important.

Angina, Unstable↗
PubMed1994

Breathlessness in microvascular angina.

In patients with microvascular angina (MA), there is some evidence from studies of plethysmography, that there are widespread microvascular abnormalities. In addition to exertional chest pain, all these patients complain of breathlessness, with no evidence of airways obstruction or resting left ventricular dysfunction. Progressive exercise testing was performed in 12 age and sex matched controls and 12 patients (three males), in whom the diagnosis of MA was established on the basis of exertional chest pain, abnormal thallium scans, and an attenuated myocardial flow response to a vasodilator challenge, with angiographically entirely normal epicardial vessels. Symptom limited exercise was performed with on line ventilation and expired gas analysis, measuring minute ventilation, oxygen consumption and carbon dioxide production and arterial blood gas values using a transcutaneous system. Anaerobic threshold was calculated by curve fitting a plot of oxygen consumption against carbon dioxide production. Compared to controls (49.7 +/- 7.3 SD% predicted maximum VO2) in patients with MA, the anaerobic threshold was reduced (41.6 +/- 5.82; P < 0.02) although still within accepted normal limits. Maximal (symptom limited) oxygen consumption, as a percentage of predicted, was reduced 60.73 +/- 16.51 compared to 87.21 +/- 5.2 (P < 0.003). The ventilatory response (VE/VCO2 l l-1 CO2 output) was significantly increased in the MA patients compared to controls (35.9 +/- 8.01 and 27.5 +/- 3.08, respectively; P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A comparison of adenosine and exercise stress 201T1 scintigraphy.

A detailed comparison of stress thallium images utilizing exercise (symptom-limited bicycle ergonometer) and adenosine (infused at 50 micrograms kg-1 min-1 increasing by 25 micrograms kg-1 min-1 every 2 min to a maximum tolerated dose) was performed in 20 patients with angiographically documented coronary disease. Ten patients were receiving beta-blockade at the time of both tests. Triple-, double- and single-vessel disease was present in eight, seven and five patients, respectively. Exercise produced a large increase in double product (8970 +/- 288 to 20,-984 +/- 690 mm Hg min-1) while adenosine produced no significant change (8440 +/- 280 to 9086 +/- 600 mm Hg min-1). Each of the three gated planar images (anterior 40 degrees and 70 degrees left anterior oblique) was divided into five equal segments. Exercise produced 44/90, 44/95 and 45/95 abnormal segments in the anterior, 40 degrees and 70 degrees views while adenosine produced 53/100, 44/100 and 52/100 abnormal segments for the same views. The total number of abnormal segments was similar in both groups (133/280 exercise and 149/300 adenosine). Each abnormal segment was analysed for degree of change between stresses using a five-point scoring system. Exercise produced eight segments which were larger by one point and 44 segments larger by two points while adenosine produced 17 and 44 segments larger by one and two points respectively. Left ventricular uptake (as % injected dose) was significantly greater in the adenosine group (1.12 +/- 0.06% versus 0.64 +/- 0.05%, P < 0.01) but right ventricular uptake was similar (0.15 +/- 0.1% versus 0.14 +/- 0.09%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1993

A comparison of dobutamine and maximal exercise as stress for thallium scintigraphy.

In the assessment and evaluation of patients with suspected coronary artery disease there is a need for pharmacological stress combined with thallium scintigraphy. Thallium images were obtained following stress both with dobutamine infusion (5-20 micrograms kg-1 min-1) and with symptom-limited bicycle ergometry in 20 patients (age 39-70 years) with chest pain who had been admitted for coronary angiography. Percentage thallium uptake was calculated using a region of interest technique. Detailed comparison was performed of the presence, size and distribution of left ventricular thallium perfusion defects; the percentage thallium uptake in ventricles, lung and liver; and the haemodynamic response to stress. Each stress produced a similar number of abnormal segments in each of three views (total EX 166/300; DOB 167/295), but exercise produced larger defects in the anterior view (P < 0.025). Thallium uptake in left and right ventricles and relative uptake to lungs were similar, but dobutamine produced higher relative liver uptake [EX 1.55 (0.67); DOB 2.97 (1.23) P < 0.0001]. Fourteen patients were able to tolerate dobutamine 20 micrograms kg-1 min-1. The ratio of peak stress to rest double product was smaller with dobutamine in both patients with (DOB 1.3; EX 2.0; P < 0.0047) and patients without beta-blockade (DOB 1.5; EX 2.4; P < 0.008). Dobutamine produced fewer conventional stress endpoints of chest pain and ST depression. In conclusion, dobutamine produces a well-tolerated incremental pharmacological stress with thallium images similar to maximal exercise, and provides a useful alternative stress in patients unable to perform adequate dynamic exercise.

Coronary Angiography↗
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↗