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The validity of using echocardiography to measure the effects of cardiovascular drugs on the heart has been investigated. A standardised method of measuring left ventricular diameters is described and used to measure variability and therefore reproducibility in 20 subjects. Immediate vari- ability was measured in 10 normal subjects. In 5 of these subjects variability was measured every few minutes, hourly, and weekly during control periods of drug studies and also after an interval of 1 year. Estimates were made of the minimum significant change in heart size which could be defined under these circumstances. Reproducibility decreased with increasing time interval between studies but overall was very good (coefficient of variation in diameters from 1 to 8%). Even with a time interval of 1 year the individual absolute difference in the mean ofdiameters was never greater than 0-3 cm. Reproducibility was similar in small groups of patients with hypertension or ischaemic heart disease (without dyskinesia).
Martin et al. (Tue,) studied this question.