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Mitral valvotomy is of established value in improving the clinical condition and life expectancy of patients with rheumatic mitral stenosis. Its value in preventing or reducing the incidence of systemic arterial embolism is less certain. A comparison of pre-and post-operative embolic incidence can only be accepted if it is clear that the method of assessing the pre-operative figure is reliable. It is shown that the figure varies according to the length of the pre-operative study, and evidence is presented to show a changing incidence with increasing length of chronic rheumatic history. By studying patients in whom the time of onset of rheumatic heart disease is accurately known, a rising embolic incidence with the passage of time is shown. A comparison is made between groups of patients who have experienced the same length of chronic rheumatic history but who differ in respect of mitral valvotomy. We conclude from our comparison that this operation does not diminish the incidence of embolism, though only about a quarter of all our patients had atrial appendagectomy at the time of valvotomy. A reduction in the incidence of recurrent embolism in a given patient after mitral valvotomy is shown but may be more apparent than real. Operative embolism, defined here as that occurring either at or within 48 hours of operation, has an incidence of 3-8%. The factors related to pre-operative, operative, and postoperative embolism are presented.

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SummaryThe symptomatic, electrocardiographic, and circulatory effects of intravenous and oral preparations of propranolol, oxprenolol, and practolol were compared in 16 patients with uncomplicated angina pectoris precipitated by exertion. The method of study included treadmill exercise, double-blind assessment, single-blind analysis, with placebo control and randomized serial comparison of each drug in each patient. The doses used were selected to give the same near-maximum suppression of the heart rate response to exercise. The symptomatic, electrocardiographic, and circulatory response of each patient to both preparations of each of the three drugs was similar. Exercise tolerance was increased in two-thirds, unchanged in one-sixth, and significantly worsened in onesixth of the studies. Electrocardiographic evidence of myocardial ischaemia was conspicuously reduced by all three drugs in most studies irrespective of their symptomatic effects. Though the exclusive choice of patients, the single dose design of the trial, and the treadmill method of assessment limit the general application of these results, they do clearly indicate that in doses that induce equal suppression of the exercise heart rate these three drugs have similar distinct anti-anginal activity. Their ancillary pharmacological properties are probably of little importance in this respect. Equally, the similarity in the symptomatic, circulatory, and electrocardiographic response to the intravenous and oral preparations suggests that metabolic breakdown products are probably of therapeutic importance only in so far as they antagonize beta-receptor activity. IntroductionThe beneficial symptomatic effects of the adrenergic betareceptor antagonists in angina pectoris are well known, but there is little information on the comparative effectiveness of different preparations. This is of particular clinical interest, as the most common drugs used-propranolol, oxprenolol, and practolol-differ conspicuously in their secondary pharmacological properties. In addition, the ingestion of these drugs is followed by the formation of metabolic degradation products with potentially different anti-anginal activities to those of the

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SummaryThe symptomatic, electrocardiographic, and haemodynamic effects of two adrenergic beta-blocking drugs, oxprenolol and propranolol, have been compared in equipotent intravenous doses in six patients with uncomplicated angina pectoris during treadmill exercise. The method of comparison included double-blind assessment and analysis with placebo control and randomized serial comparison in each patient. Both drugs produced an equal amelioration in symptoms in most of the patients. This was closely correlated with improvement in the electrocardiographic changes and a significant reduction in the exercising heart rate and systemic arterial pressure. This method of double-blind combined subjective and objective assessment carries distinct advantages in the comparative assessment of drug treatments in angina pectoris.Introduction Though a number of adrenergic beta-blocking drugs are available for the symptomatic treatment of severe angina pectoris there is little information on their comparative effectiveness. This report concerns a comparative study of the symptomatic, electrocardiographic, and circulatory effects of two such drugs, oxprenolol and propranolol, in patients with angina pectoris.

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