Abstract-Investigation of arterial stiffness, especially of the large arteries, has gathered pace in recent years with the development of readily available noninvasive assessment techniques. These include the measurement of pulse wave velocity, the use of ultrasound to relate the change in diameter or area of an artery to distending pressure, and analysis of arterial waveforms obtained by applanation tonometry. Here, we describe each of these techniques and their limitations and discuss how the measured parameters relate to established cardiovascular risk factors and clinical outcome. We also consider which techniques might be most appropriate for wider clinical application. Finally, the effects of current and future cardiovascular drugs on arterial stiffness are also discussed, as is the relationship between arterial elasticity and endothelial function.
Arterial StiffnessData from the Framingham Heart Study have determined how systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP; the difference between SBP and DBP) change with advancing age. 1 DBP, largely determined by peripheral arterial resistance, increases until middle age and then tends to fall. In contrast, SBP and PP, influenced more by the stiffness of large arteries, as well as peripheral pulse wave reflection and the pattern of left ventricular ejection, increase continuously with age. Changes in the stiffness of the large arteries, such as the aorta and its major branches, largely account for the changes in SBP, DBP, and PP that occur from 50 years of age onward. Although DBP has traditionally been the major focus in the treatment of hypertension, over recent years SBP has become recognized as a stronger cardiovascular risk factor in older people. Thus, SBP has greater predictive value than DBP for coronary heart disease (CHD) in older people (Ͼ60 years). 2,3 Isolated systolic hypertension (ISH; SBP Ն140 mm Hg and DBP Ͻ90 mm Hg), is the most common subtype of hypertension in the middle aged and is overwhelmingly so in the elderly. 4 It is a major risk factor for stroke, 5 CHD, 2,3 and cardiovascular and total mortality. 6,7 Furthermore, measurement of SBP alone identifies Ͼ90% of hypertensives according to the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure VI criteria, whereas DBP alone identifies only Ϸ20%. 8 The treatment of ISH with conventional antihypertensive drugs is of proven clinical benefit. 9,10 However, although it is recognized that few hypertensives are controlled to target pressures, 11 it is much more commonly