Long term survival of patients mobilised early after acute myocardial infarction

A Welsh multicentre trial of early (fifth day) compared with late (tenth day) mobilisation in 742 patients after uncomplicated myocardial infarction, reported previously, found that there were no significant differences in survival during the first year, but a partial follow up beyond the first year survival showed a significantly reduced survival during the second and third years among patients mobilised early. A full 10 year follow up of all patients admitted to the trial was therefore carried out. A small difference in survival was confirmed, which reached about 5% at four years; but the difference was not statistically significant. Further analysis suggested the possibility of real differences in survival in certain subgroups, but the present evidence was not sufficient to provide contraindication to mobilisation five days after uncomplicated myocardial infarction.

Isolated perfused rabbit coronary artery and aortic strip preparations: the role of endothelium-derived relaxant factor

Isolated perfused coronary arteries and aortic ring preparations of rabbits were studied, both with intact endothelium and with endothelium removed by K-rich solution and friction respectively. Constrictor dose-responses to histamine, acetylcholine, phenylephrine and 5-hydroxytryptamine (5-HT) were measured. They were greatly depressed by the presence of endothelium in coronary preparations. In aortic preparations endothelium affected dose-responses relatively little, depressing the response to acetylcholine but apparently increasing the responses to the other three agents. Acetylcholine relaxed pre-constricted coronary or aortic preparations but only when endothelium was present. This relaxation was inhibited by quinacrine or hydroquinone. Aortic preparations had resting tone which could be increased by hydroquinone if endothelium was present, suggesting continual release of endothelium-derived relaxant factor (EDRF) at rest. When allowance was made for basal EDRF activity in aortic preparations, the maximal constrictor response to acetylcholine remained lower in the presence of endothelium, consistent with acetylcholine stimulation of EDRF, but maximal constrictor responses to the other three agents were the same with and without endothelium, suggesting that the direct constrictor response overrides EDRF activity.

Ergometrine-induced arterial dilatation: an endothelium-mediated effect

Ergometrine has generally been regarded as a vasoconstrictor and is used clinically to provoke coronary vasospasm in susceptible patients [3, 8, 9]. The ergometrine response appears however to be complex in that it can be biphasic, the constrictor response being preceded by an initial dilator response in experimental models [4]. The explanation for this is unknown, as is the underlying mechanism responsible for the clinical condition of coronary vasospasm. We have investigated this biphasic response in isolated artery preparations and shown that the dilator component is due to ergometrine-induced release of endothelium-derived relaxant factor (EDRF).

The nature of endothelium-derived vascular relaxant factor

The existence of endothelium-derived vascular relaxant factor (EDRF) was postulated by Furchgott and colleagues when they observed that acetylcholine paradoxically relaxed preconstricted aortic strip preparations by an endothelium-dependent mechanism. This phenomenon has since been demonstrated in different blood vessels and mammalian species and it can be elicited by several other agents. EDRF has been thought to be a humoral agent, a lipoxygenase derivative and possibly a free radical. In the study reported here, by using aortic preparations from the rabbit, alone and in cascade experiments with isolated perfused coronary preparations, we demonstrate definitively that EDRF is a humoral agent. It is released from unstimulated aortic preparations containing endothelium, its release can be stimulated for prolonged periods by acetylcholine, and it is not a lipoxygenase derivative or free radical but an unstable compound with a carbonyl group at or near its active site.

The psychological side effects of acebutolol and atenolol

We have measured the psychological effects of acebutolol and atenolol in sixteen patients with essential hypertension. The drugs were administered in a randomized, placebo-controlled, double-blind manner, in single daily doses of 100 mg atenolol, 400 mg acebutolol or placebo for periods of 6 weeks, each drug period being separated by a placebo period. At each 2 weekly clinic visit, a questionnaire designed for assessment of state anxiety and state arousal was administered for self-completion. Arousal was significantly reduced by atenolol over the whole 6 weeks of administration. It was not affected by acebutolol. Anxiety was significantly reduced by acebutolol but only at the first of the three 2 weekly assessments on treatment. It was not affected by atenolol. Differences in the psychological effects of these two beta-adrenoceptor blockers are discussed in terms of their lipid solubility and haemodynamic effects.

beta-Adrenoceptor hypersensitivity after stopping oxprenolol: discrepant findings not attributable to methodology

Using isoprenaline and glyceryl trinitrate (GTN) induced tachycardia we have compared the rebound beta-adrenoceptor hypersensitivity on stopping slow-release and conventional oxprenolol in young normotensive subjects. Heart rate on standing with GTN rose after stopping slow-release and conventional oxprenolol to peak levels on day 2 or 3 significantly greater than corresponding control levels off treatment on day 5. The isoprenaline CD25 (the dose required to increase heart rate by 25 beats/min) fell after stopping conventional oxprenolol to a significantly lower level on day 3 than the control level off treatment on day 5. Contrary to a recent report describing no rebound beta-adrenoceptor hypersensitivity on stopping slow-release oxprenolol we have demonstrated it after stopping slow release as well as conventional oxprenolol.

Does it help to undiagnose angina?

We reported recently the results of re-evaluating a series of 64 patients still experiencing pain originally diagnosed as angina but with normal coronary arteriograms. A musculoskeletal cause for the chest pain was established in 38 and an oesophageal cause in 17 of these patients. We here report these patients' self-assessment of their pain 2 years after this diagnostic reclassification. It is clear that the effects of a diagnosis of angina are not easily rescinded even when the non-cardiac cause of the chest pain is identified.

Heart failure in the elderly

The acute and chronic compensatory mechanisms underlying the clinical syndrome of heart failure are summarised. Problems of diagnosing heart failure and causes of heart failure, particularly in the elderly, are noted, against a framework of reference of the determinants of cardiac output. The main approaches to treating heart failure are reviewed against the same framework of reference.

Inotropic beta-blocking potency (pA2) and partial agonist activity of propranolol, practolol, sotalol and acebutolol

The beta-blocking potencies (pA2 values) and cumulative dose responses of the direct effects of dl-propranolol, practolol, acebutolol and sotalol have been characterised in respect of the mechanical performance of isolated cat papillary muscle preparations. pA2 values calculated from antagonism of each of the drugs to the inotropic effect of isoprenaline at 29 degrees C were: dl-propranolol 8.3, practolol 5.6, acebutolol 7.5 and sotalol 4.8. The responses in reserpinized muscles were similar to those in non-reserpinized preparations. dl-Propranolol at concentrations of 10(-5) and 10(-4) M depressed peak developed force (DF) and rate of force development (+dF/dt) by 20% and 60% respectively, with similar but smaller changes in maximum unloaded shortening velocity ('Vmax'). Practolol and sotalol increased DF and +dF/dt by less than 10% at 10(-5) M and by 10-20% at 10(-4) M, with similar but smaller changes in Vmax. Sotalol induced prolonged biphasic contractions at 10(-4) M. Acebutolol had no effect on DF, +dF/dt, or Vmax. Time to peak force and half isometric relaxation time were not altered by any drug. Practolol and acebutolol, generally considered to have partial agonist activity, exerted this to a negligible degree in respect of inotropic effect at less than or equal to 10(-5) M.

Pharmacokinetic studies of various preparations of glyceryl trinitrate

1 The pharmacokinetics and pharmacodynamics of five pharmaceutical preparations of glyceryl trinitrate (GTN) have been studied in six healthy volunteers. 2 Peak plasma GTN levels of 1.4 +/- 0.1 ng/ml were achieved at 3 min after sublingual administration (0.5 mg); 2.8 +/- 0.6 ng/ml and 2.5 +/- 0.3 ng/ml at 2 h and 4 h after Nitrocontin (6.4 mg) and Sustac (6.4 mg) respectively; 2.7 +/- 0.1 ng/ml and 2.5 +/- 0.2 ng/ml at 30 min after the cream (23 mg) and ointment (35 mg) respectively. 3 The mean times to reach half peak plasma GTN levels were 4.2 +/- 0.7 min after sublingual GTN, 6.5 +/- 0.9 h after Nitrocontin, 4.1 +/- 0.7 h after Sustac, 46.1 +/- 10.2 min after the ointment and 50.2 +/- 39.2 min after the cream. 4 Plasma nitrate (NO3) levels were undetectable after sublingual administration; peak NO3 levels were 0.48 +/- 0.03 microgram/ml at 4 h after Nitrocontin, 0.45 +/- 0.02 microgram/ml at 6 h after Sustac, 0.68 +/- 0.04 microgram/ml at 6 h (end of study) after the ointment and 0.63 microgram/ml at 4 h after the cream. 5 Plasma nitrite (NO2) was undetectable after sublingual GTN and peak NO2 levels were 0.48 +/- 0.04 microgram/ml at 2 h after Nitrocontin, 0.48 +/- 0.02 microgram/ml at 2 h after Sustac, 0.69 +/- 0.02 microgram/ml at 1 h after the ointment and 0.64 +/- 0.02 microgram/ml at 1 h after the cream. 6 Blood pressure (BP) declined throughout the 11 min of the study after sublingual GTN but did not change significantly after Nitrocontin or Sustac. After the ointment and the cream BP fell to the lowest level 30-60 min after administration and remained low throughout the 6 h of the study. 7 Heart rate (HR) increased to a maximum 5 min after sublingual administration with no significant increase after Nitrocontin or Sustac. After the ointment and the cream HR increased gradually to a maximum 30-60 min after administration remaining high throughout the rest of the study.

Maintenance of the inotropic effect of digoxin on long-term treatment

M-mode echocardiograms and systolic time intervals were recorded before and six weeks after stopping digoxin in 11 patients in sinus rhythm to see whether the inotropic effect of digoxin was maintained with long-term treatment. Significant changes indicating a reduction in inotropic state on stopping digoxin were observed in the group. Clinical deterioration occurred in only one patient, associated with evidence of initially impaired cardiac function rather than an atypical response to digoxin. This study provides evidence that chronic digoxin treatment does continue to exert a positive inotropic effect.

Diagnosis of oesophageal spasm by ergometrine provocation

Oesophageal spasm may mimic the pain of myocardial ischaemia. Forty-two patients who were thought to have angina until investigations failed to show any cardiovascular abnormality, were examined for oesophageal disease. Ergometrine provocation during oesophageal manometry caused significant deterioration in oesophageal motility, associated with familiar pain, in 24 patients. Ten age-matched controls were examined in a similar way and ergometrine produced motility changes in four and pain in two. Six volunteers with coronary artery stenosis and exercise-induced angina did not develop oesophageal motility changes during the pain. Ergometrine provocation is useful in establishing the diagnosis of oesophageal spasm in patients with recurrent angina-like pain but no cardiac abnormality.

Perverse T waves and chronic beta-blocker treatment

Images

The effect of chronic propranolol treatment on overnight plasma levels of anterior pituitary and related hormones

1 Treatment of eight healthy males with propranolol (80 mg twice daily) for 6 weeks resulted in a significant reduction in overnight plasma levels of prolactin and LH. 2 Plasma testosterone levels were elevated whilst GH and cortisol were unchanged by such treatment. 3 Measurement of overnight hormone levels 48 h after discontinuing treatment showed no evidence of a 'rebound' phenomenon. 4 Cortisol, GH, prolactin, and testosterone plasma levels all showed time dependent changes: propranolol treatment significantly altered the time course of cortisol but not of the other hormones. 5 The effects of chronic propranolol treatment are discussed in terms of a probable direct central action of the drug. In addition the lowered plasma prolactin levels may directly contribute to the hypotensive action of propranolol.

The effects of propranolol and acebutolol on the overnight plasma levels of anterior pituitary and related hormones

1 The effects of single evening doses of the beta-adrenoceptor blocking agents propranolol (80 mg orally) and acebutolol (200 mg orally) on plasma levels throughout the night of prolactin, growth hormone, luteinising hormone, follicle stimulating hormone, cortisol and testosterone have been studied in seven healthy male volunteers. 2 Three way analysis of variance showed that acebutolol significantly reduced circulating levels of prolactin and follicle stimulating hormone, but did not alter the levels of the other hormones studied. 3 Propranolol significantly reduced follicle stimulating hormone and testosterone, and significantly increased circulating levels of cortisol, but caused no change in the other hormones studied. 4 Prolactin, luteinising hormone, testosterone and cortisol showed a significant variation with time indicating the existence of a diurnal rhythm in the pattern of their secretion. 5 There was a significant inter-subject variability in all the hormones studied. 6 There was a significant between-subject variation in response to both propranolol and acebutolol. 7 Different subjects showed significant variations with respect to time in prolactin, growth hormone and cortisol levels. 8 Neither propranolol nor acebutolol significantly altered the time course of secretion of any of the hormones studied. 9 Possible relationships of these beta-adrenoceptor blocker-induced changes in anterior pituitary and related hormones to the antihypertensive mechanism of acebutolol and propranolol are discussed.

Just a pinch between the cheek & gum

At least in part, through a skillful manipulation of the public by the tobacco industry, the use of smokeless tobacco is rapidly increasing, especially among young male athletes and students in high school and colleges. Advertising implies that smokeless tobacco habits are innocuous and safe, but existing scientific evidence indicates that dipping and chewing are potentially harmful to one's health. Health professionals are urged to advise patients and students concerning the potential hazards of using smokeless tobacco. Further, health professionals should take a strong public stance in opposition to the current dipping and chewing advertising campaigns aimed at youth. These advertisements totally ignore the possible health hazards of smokeless tobacco. If the tobacco companies are allowed to continue to advertise smokeless tobacco in the same manner that they use to promote cigarette smoking, then some effort should be directed to require health warnings in these advertisements. In fact, some serious consideration should most likely be given to banning this new wave of tobacco marketing in the interest of public health, just as was the case with cigarette advertisements, especially in light of the fact that these ads are primarily targeted to young boys and men.