Pulse pressure and arterial elasticity.

The last decade has seen increased interest in the mechanical interaction between the heart and the arterial system. In particular, it has been suggested that increased arterial stiffness is associated with the development of cardiovascular disease and may even predict its development at an early stage before vascular lesions or external symptoms become evident (reviewed in references 1 and 2). The reasons for this association are not fully understood, although we have known for almost 200 years that pulse pressure is affected by the distensibility of the arterial system, its dimensions and the presence of wave reflections.3 Accordingly, renewed attention has been directed at methods of measuring arterial elasticity, either directly or by way of ‘surrogates’. The review in this issue by Mackenzie and colleagues discusses the clinical value of such measurements. They reiterate the argument outlined by O'Rourke:4 that after the introduction of the sphygmomanometer, the shape of the pressure wave was neglected in favour of a simple numerical representation (i.e. pulse pressure), and that with the development of improved methods, analysis of the pulse wave is back in fashion. Whatever the reasons, it is clear that the long‐term performance of the heart, like that of all machines, depends not only on the average load to which it is exposed, but at least as much on time‐varying and peak loads. It is surprising, at least with the benefit of hindsight, that more attention has not been given to this aspect of the circulation. To explain the relationship between forces generated within the myocardium, pressure within the ventricles, and changes in the shape and height of the pressure pulse as it travels away from the heart, requires a model of the circulation which, constrained by the observed anatomy and mechanical properties of the circulation, is able to predict …