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Biomedical subjects

D N Croft

Publications and source records attributed to D N Croft.

At least 37 records · Page 2Linked to original sources
PubMed1984

Assessment of pulmonary ventilation scans using xenon-127 in the diagnosis of pulmonary embolism.

Pulmonary ventilation scans using 127Xe were compared with scans using 133Xe in the diagnosis of pulmonary embolism. A perfusion scan using 99mTc -microspheres and ventilation scans with each of the xenon isotopes were performed on 44 patients referred for lung scanning to confirm or exclude a suspected clinical diagnosis of pulmonary embolism. No significant difference was found in the frequency of diagnosis of pulmonary embolism when comparing each of the ventilation scans with the corresponding perfusion scan. For reasons discussed, 127Xe may be more useful than 133Xe for pulmonary ventilation scanning.

Humans↗
PubMed1983

Recovery of renal function after prolonged dialysis and transplantation.

Out of 250 patients with renal failure, seven (2.8%) treated by regular haemodialysis alone (four) or given cadaveric allografts (three) later showed recovery of function of their own kidneys lasting from one to four years. In the patients receiving haemodialysis alone recovery was easily recognised from their serum creatinine concentrations, but in those with transplants recovery was discovered unexpectedly during radionuclide scanning. These findings suggest that recovery of renal function may be more common than generally recognised, which should be borne in mind when beginning renal replacement treatment and particularly when contemplating bilateral nephrectomy.

Female↗
PubMed1983

Effect of beta adrenergic blockade on thallium-201 myocardial perfusion imaging.

Nine patients with stable angina (group 1) underwent maximal treadmill stress testing and thallium-201 (201T1) myocardial scintigraphy after intravenous propranolol hydrochloride, and after placebo. Though seven of the nine patients exercised longer after propranolol than after placebo, this difference did not reach statistical significance. Propranolol, however, significantly reduced the mean maximum rate pressure product. Comparison of the perfusion scans on and off propranolol showed that in 36 out of 90 of the myocardial segments recorded (nine patients, five segments scanned twice per patient), only one of the scans showed a defect. In 24 out of 36 of these the propranolol scan was negative, the defect appearing in the placebo scan. Defects present on both scans but differing significantly in size occurred in 22 out of 54 view pairs (nine patients, three views after exercise and three views after redistribution on propranolol and on placebo), and in 19 of these the smaller defect was seen in the propranolol scan. In one of the nine patients, the propranolol scan was normal (false negative), whereas defects corresponding to angiographically proven coronary artery lesions were seen on the placebo scan. Six patients (group 2) were maximally exercised after propranolol and then re-exercised to the same rate pressure product on placebo. Again 16 out of 60 of the segment pairs disagreed and in 10 of these the unmatched defect was present on the placebo scan. In 10 out of 14 discrepant view pairs, the smaller defect occurred on the propranolol scan. Thus in patients taking propranolol, negative results do not exclude coronary artery disease, and perfusion defects (if present) though accurately reflecting the presence of disease may underestimate its true extent.

Adult↗
PubMed1982

Effects of early administration of a highly purified hyaluronidase preparation (GL enzyme) on myocardial infarct size.

79 patients with suspected myocardial infarction entered a randomised trial to establish the safety of early intravenous administration of a highly purified hyaluronidase preparation (GL enzyme) and to assess its effects on eventual infarct size as measured by electrocardiographic, enzymatic, and scintigraphic criteria. Of the 71 patients with infarction, 35 received GL enzyme and 36 placebo within 6 h of the onset of chest pain. GL enzyme injected into a peripheral vein produced no adverse changes in the clinical, haemodynamic, biochemical, or haematological variables studied. GL enzyme reduced precordial electrocardiographic indices of infarct size as reflected by a diminution (p less than 0.02) in the degree of both R wave loss and Q wave development. In addition, the number of leads developing pathological Q waves (N delta Q greater than or equal to 2), a sign of progression from ischaemia to necrosis, was reduced (p less than 0.05) after GL enzyme treatment. However, there were no significant differences in infarct size as measured by cumulative creatine kinase MB isoenzyme release or technetium-99m pyrophosphate scintigraphic infarct area, or in clinical outcome during the hospital stay. Interpretation of the enzymatic and scintigraphic data was complicated by chance bias in pre-treatment randomisation which resulted in more (p less than 0.05) patients with severe haemodynamic impairment (and hence probably larger infarct sizes) entering the GL enzyme group. Nonetheless, a favourable effect of GL enzyme on infarct size was demonstrated by precordial electrocardiographic QRS mapping, here each patient acts as his or her own control.

Clinical Trials as Topic↗
PubMed1981

Advantages of technetium pyrophosphate scintigraphy over plasma enzyme analysis in estimation of anterior myocardial infarct size.

Infarct size was estimated by cumulative creatine kinase MB isoenzyme (CKMB-r) release and by technetium 99m stannous pyrophosphate (TcPYP) scintigraphy in 27 patients with acute anterior myocardial infarction. In eight patients, scintigraphy showed a central area of reduced tracer uptake surrounded by a peripheral rim of increased TcPYP accumulation ("doughnut" pattern). This appearance occurred only in large infarcts and the maximal scintigraphic area (51.3 +/- 2.8 cm2, mean +/- SEM) in this group was significantly greater than that in the remainder (28.1 +/- 2.5 cm2). Correlation between CKMB-r and maximal scintigraphic infarct area was moderate in the whole group. Exclusion of patients, however, with "doughnut" scintigrams in which correlation was very poor, resulted in substantial improvement in the remainder. It is suggested that in the central regions of large "doughnut" infarcts, reduced blood flow hinders the efflux of CKMB from the centre causing an underestimate of infarct size. Pyrophosphate scintigraphy appears to be more accurate than CKMB release in measuring the size of these large anterior infarcts.

Adult↗
PubMed1980

Carbenoxolone and gastric Technetium-99m pertechnetate uptake in patients with gastric ulceration.

Technetium-99m pertechnetate is known to concentrate in the stomach following intravenous injection, but there is controversy on the cellular site of this uptake, with evidence for both the mucous and parietal cells being primarily responsible. Gastric uptake following intravenous pertechnetate has been studied in patients with non-ulcer dyspepsia and peptic ulcer, using a gamma camera and computer processing with regions of interest. Under identical conditions in any one patient, quantification of uptake at 20 min is reproducible to an accuracy of +/- 6%. Six patients with gastric ulcer were studied before and 3 weeks after starting treatment with carbenoxolone. There was a rise in uptake in 5 subjects with a mean percentage increase of 25%. The effect of cimetidine was studied in six patients with either gastric or duodenal ulcer. There was little change in uptake (mean 6%). These preliminary data would support the hypothesis that concentration of pertechnetate occurs primarily in the mucous cell.

Adult↗