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Biomedical subjects

C Layton

Publications and source records attributed to C Layton.

At least 19 recordsLinked to original sources
PubMed1994

Failure of epoprostenol (prostacyclin, PGI2) to inhibit platelet aggregation and to prevent restenosis after coronary angioplasty: results of a randomised placebo controlled trial.

OBJECTIVE: To study the effect of epoprostenol (prostacyclin, PGI2) given before, during, and for 36 h after coronary angioplasty on restenosis at six months and to evaluate the transcardiac gradient of platelet aggregation before and after percutaneous transluminal coronary angioplasty (PTCA) in treated and placebo groups. DESIGN: Double blind placebo controlled randomised study. PATIENTS: 135 patients with successful coronary angioplasty. METHODS: Intravenous infusion of PGI2 (4 ng/kg/ml) or buffer was started before balloon angioplasty and continued for 36 hours. Platelet aggregation was measured in blood from the aorta and coronary sinus before and after PTCA in each group. Routine follow up was at six months with repeat angiography and there was quantitative assessment of all angiograms (those undertaken within the follow up period and at routine follow up). PRESENTATION OF RESULTS: Restenosis rates in treated and placebo groups determined according to the National Heart, Lung and Blood Institute definition IV. Comparison at follow up between the effect of treatment on mean absolute luminal diameter and mean absolute follow up diameter in the placebo group. Comparison of acute gain and late loss between groups. RESULTS: Of 125 patients available for assessment 23 were re-admitted because of angina within the follow up period. Quantitative angiography showed restenosis in 15 (10 in the PGI2 group and five in the placebo group). Of 105 patients evaluated at six month angiography there was restenosis in nine more in the PGI2 group and 18 more in the placebo group. Total restenosis rates (for patients) were 29.2% for PGI2 and 38.3% for placebo (NS). The mean absolute gain in luminal diameter was 1.84 (0.76) mm in the PGI2 group and 1.58 (0.56) mm in the placebo group (p = 0.04); the late loss in the PGI2 group was also greater (0.65 (0.94) mm vs 0.62 (0.89) mm (NS) and there was no significant difference in final luminal diameter at follow up between the two groups (1.83 (0.88) mm v 1.59 (0.60) mm). The transcardiac gradient of quantitative platelet aggregation increased after PTCA in both groups, indicating that PGI2 in this dose did not affect angioplasty-induced platelet activation. Mean (SD) platelet activation indices in the PGI2 group were pre PTCA aorta 8.4 (4.1) v coronary sinus 8.8 (4.0) (p = 0.001) and post PTCA aorta 8.9(3.0) v coronary sinus 12.9 (5.7) (p = 0.001). In the placebo group the values were pre PTCA aorta 7.6 (3.3) v coronary sinus 7.4 (3.6) (p = 0.001) and post PTCA aorta 7.6(2.8) v coronary sinus 11.2(4.3) (p = 0.001). CONCLUSION: The dose of PGI2 given was designed to limit side effects and as a short-term infusion did not significantly decrease the six month restenosis rate after PTCA. The sample size, which was determined by the original protocol and chosen because of the potency of the agent being tested, would have detected only a 50% reduction in restenosis rate. There was, however, no effect in the treated patients on the increased platelet aggregation seen in placebo group as a result of angioplasty. Angioplasty is a powerful stimulus to blood factor activation. Powerful agents that prevent local platelet adhesion and aggregation are likely to be required to reduce restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1994

Clinical experience with the Wiktor stent in native coronary arteries and coronary bypass grafts.

OBJECTIVES: To evaluate the results of implantation of Wiktor tantalum wire coronary stents in stenosed or occluded coronary vessels or in saphenous vein bypass grafts. DESIGN: A retrospective analysis of clinical and angiographic data from patients treated with tantalum wire stents implanted by one operator at two centres. PATIENTS: 52 patients undergoing conventional balloon angioplasty had 67 lesions treated by stents after acute or threatened closure of the target vessel, or because the lesions concerned were considered to be at particularly high risk of becoming restenosed, or because the result of primary angioplasty was inadequate. RESULTS: 65 of the 67 lesions were successfully stented although in two cases the first attempt failed and a second stent was then implanted successfully. There were no cases of stent occlusion and no myocardial infarctions in hospital or in the follow up period of 1-20 months. Eight patients had haemorrhagic complications that were minor in 4. One patient later had coronary bypass surgery after failure to stent a lesion. Angiographic follow up at a mean of 6 months after stenting showed restenosis associated with 4 of 47 stents studied. All patients with chest pain had had repeat angiography, and 84% of those without symptoms also agreed to reinvestigation after about 6 months. CONCLUSIONS: The Wiktor tantalum wire stent is an effective means of treating acute complications during angioplasty and seems to offer hope of a significant reduction in the rate of late restenosis in both native coronary vessels and saphenous vein bypass grafts. A prospective comparison of balloon angioplasty and stenting is needed.

Adult↗
PubMed1994

Emergency surgical revascularisation for coronary angioplasty complications.

OBJECTIVES: To evaluate trends in referrals for emergency operations after percutaneous transluminal coronary angioplasty (PTCA) complications; to analyse morbidity and mortality and assess the influence of PTCA backup on elective surgery. DESIGN: A retrospective analysis of patients requiring emergency surgical revascularisation within 24 hours of percutaneous transluminal coronary angioplasty. PATIENTS: Between January 1980 and December 1990, 75 patients requiring emergency surgery within 24 hours of percutaneous transluminal coronary angioplasty. SETTING: A tertiary referral centre and postgraduate teaching hospital. RESULTS: 57 patients (76%) were men, the mean age was 55 (range 29-73) years, and 30 (40%) had had a previous myocardial infarction. Before PTCA, 68 (91%) had severe angina, 59 (79%) had multivessel disease, and six (8%) had a left ventricular ejection fraction of less than 40%. A mean of 2.1 grafts (range one to five) were performed; the internal mammary artery was used in only one patient. The operative mortality was 9% and inhospital mortality was 17%. There was a need for cardiac massage until bypass was established in 19 patients (25%): this was the most important outcome determinant (P = 0.0051) and was more common in those patients with multivessel disease (P = 0.0449) and in women (P = 0.0388). In 10 of the 19 cases a vacant operating theatre was unavailable, the operation being performed in the catheter laboratory or anaesthetic room. These 19 patients had an operative mortality of 32% and inhospital mortality of 47%, compared with 2% and 7% respectively for the 56 patients who awaited the next available operating theatre. Complications included myocardial infarction, 19 patients (25%); arrhythmias, 10 patients (3%); and gross neurological event, two patients (3%). The mean intensive care unit stay was 2.6 days (range 1 to 33 days) and the mean duration of hospital admission was 13 days (range 5-40 days). CONCLUSIONS: Patients undergoing emergency surgery after PTCA complications have a substantially increased inhospital mortality and morbidity. PTCA in this unit continues to require surgical cover. Delays in operating on stable patients in centres which operate a "next available theatre" backup policy may not differ from some units performing PTCA with offsite cover for PTCA complications. Particularly in the presence of multivessel disease, however, PTCA complications may be associated with the need for "crash" bypass and such patients are unlikely to survive hospital transfer. The proportion of patients requiring "crash" bypass has increased during the period reviewed because of the extent of disease in the emergency surgical group increased. These results indicate that surgery should not be denied to these patients.

Adult↗
PubMed1993

Blocking and countering in traditional Shotokan karate kata.

Analysis of the 1183 techniques forming the twenty-seven Shotokan karate kata (forms) widely practised today shows a significant preference for blocking over counter-offensive techniques. This may be interpreted as evidence to support Karate-do as a Way of self-defense and non-violence.

Female↗
PubMed1993

Speed of technique and age in Shotokan karateka.

Correlations between reaction-time + movement-time and age on two punching and two kicking techniques were nonsignificant. This was interpreted as providing some evidence to support the contention that the very practice of Shotokan karate keeps speed of technique at a fast level.

Adolescent↗
PubMed1993

Reaction + movement-time and sidedness in Shotokan karate students.

Reaction + movement-times on four counter-offensive techniques of Shotokan karate were found not to differ with regard to sidedness, despite right-sided bias in such techniques in Shotokan kata (forms) previously recorded, and with no attempt to correct the bias in basics and/or sparring over a long period.

Adult↗
PubMed1993

Karate for self-defense: an analysis of Goju-ryu and Kyokushinkai kata.

12 Goju-ryu and 24 Kyokushinkai kata (forms) widely practised today were analysed for blocking and counter-offensive techniques. A statistically significant preference was found for blocking in Goju-ryu kata and a significant preference for counter-offensive techniques in Kyokushinkai kata. The kata from both styles were seen as fostering nonviolence in their practitioners, however.

Aggression↗
PubMed1993

Sidedness in Shotokan karate kata.

The 1183 techniques forming the 27 kata (forms) of Shotokan karate, were analysed for left/right bias. Punches/spear-hands, strikes and kicks showed a significant right-sided bias, but not for blocks and the major stances.

Adult↗
PubMed1989

Phase and amplitude analysis of exercise digital left ventriculograms in patients with coronary disease.

Phase and amplitude analysis was applied to intravenous digital left ventriculograms to avoid the artefacts associated with image subtraction. Eight controls and 40 patients with known coronary artery disease underwent digital left ventriculography before and after a symptom limited supine bicycle exercise test. The resultant images were subjected to phase and amplitude analyses. In the control group there was no deterioration in left ventricular wall motion after exercise. In 30 of the 40 patients there was a deterioration in wall motion on exercise. This group contained all eight patients with three vessel disease and 12 of the 17 patients with two vessel disease. Ten patients showed no change in wall motion--five with one vessel disease and five with two vessel disease. Phase and amplitude analysis of digital left ventriculograms is a method of detecting exercise induced myocardial ischaemia that may help in the assessment of patients with coronary artery disease.

Coronary Disease↗
PubMed1988

Responses of neonates to parents' and others' voices.

Infants stimulated with 8-s recordings of speech and voices reading numbers showed a discrimination between their own mothers' and alien voices. In general, the infants' heart rates rose more in response to their mothers' than to an alien voice. However, infants tested less than 24 h after birth responded with significant heart rate deceleration to the mother's spontaneous speech and to the mother reading numbers. Response to the father's voice was also deceleration but to all alien voices was acceleration. Older infants' responses also tended to be acceleratory to most stimuli. Results support the suggestion that sounds which are repeatedly experienced before birth (especially the mother's voice) become familiar to the fetus so that the neonate responds selectively by orienting to them during the first few hours after birth.

Arousal↗
PubMed1988

Arrival-time analysis of intravenous digital aortograms in aortic dissection.

Arrival-time analysis was applied to intravenous digital aortograms. A single static image was produced by representing the time to 90% maximum density for each image pixel on a grey scale. Arrival-time analysis confirmed the diagnosis in four of six patients with aortic dissection that had been shown by image subtraction. In a further three patients with no dissection the arrival-time images were normal. In two patients with surgical repair of the ascending aorta, residual false lumens were shown by both subtraction and arrival-time analysis. In one of these cases arrival-time analysis prompted reanalysis of the subtraction image that had previously been interpreted as showing a normal aorta. Arrival-time analysis provides a static image of aortic dissection, which helps to overcome subtraction artefact.

Aortic Dissection↗