AMBULATORY BLOOD-PRESSURE

Indirect methods of recording blood pressure suffer from all the known methodological inaccuracies of the Riva Rocci-Korotkoff technique, are slow-moving and are difficult to use for repeated measurements. Nevertheless, the causal indirect blood pressure has powerful predictive value for cardiovascular disease in populations. It is not known if the same applies to individuals, but it is thought that repeated measurements of ambulatory subjects are more likely to provide accurate prognostic information. There are some indications that this may be true, but the most valuable information on blood pressure and its variation has been provided by the Oxford technique for direct intra-arterial recording of blood pressure. The application of coherent averaging to data from these studies has allowed the description of a circadian rhythm of blood pressure and its reversal in central and peripheral autonomic denervation. Studies in chronic stable angina have outlined the essential differences between ‘spontaneous’ and induced angina, and studies in congestive heart failure have directed attention to the heart as a central regulator of the circulation. Attempts to develop indirect techniques which can match the direct technique for accuracy and speed have not been very successful, but indirect techniques must be the ultimate object of the research and development in this field.