Central aortic pressure and clinical outcomes.

Conventional brachial blood pressure (BP) measurement by sphygmomanometry is simple and has remained the gold standard for the measurement of BP for over a century. Moreover, it is well established that brachial BP levels are predictive of cardiovascular morbidity and mortality. When we measure brachial BP, we do so with the assumption that the pressure measured over the brachial artery accurately reflects the pressures at the ‘business end’ of the circulation, notably the larger ‘central arteries’, that is, the aorta. Intuitively, it seems reasonable to assume that if we could routinely and reliably measure pressures in the central arteries, these central aortic pressures should be more predictive of target organ damage and clinical outcomes than brachial BP. On the other hand, if brachial BP measurements always faithfully reflected the pressures in these central arteries, then there would be no need to consider measurement of central aortic pressures and the measurement of brachial BP would suffice. Alas, brachial BP is not the perfect surrogate for central aortic pressure, and brachial BP levels do differ from those recorded contemporaneously for the central circulation, either directly at cardiac catheterization or derived noninvasively by analysis of the radial pressure waveform.