The dicrotic notch as alternative time-reference point to measure local pulse wave velocity in the carotid artery by means of ultrasonography

In recent years, great emphasis has been placed on the role of arterial stiffness in the development of cardiovascular diseases. Indeed, the assessment of arterial stiffness is increasingly used in the clinical assessment of patients. Although several papers have previously addressed the methodological issues concerning the various indices of arterial stiffness currently available, and their clinical applications, clinicians and researchers still report difficulties in selecting the most appropriate methodology for their specific use. This paper summarizes the proceedings of several meetings of the European Network for Non-invasive Investigation of Large Arteries and is aimed at providing an updated and practical overview of the most relevant methodological aspects and clinical applications in this area.

Although various studies reported that pulse pressure, an indirect index of arterial stiffening, was an independent risk factor for mortality, a direct relationship between arterial stiffness and all-cause and cardiovascular mortality remained to be established in patients with essential hypertension. A cohort of 1980 essential hypertensive patients who attended the outpatient hypertension clinic of Broussais Hospital between 1980 and 1996 and who had a measurement of arterial stiffness was studied. At entry, aortic stiffness was assessed from the measurement of carotid-femoral pulse-wave velocity (PWV). A logistic regression model was used to estimate the relative risk of all-cause and cardiovascular deaths. Selection of classic risk factors for adjustment of PWV was based on their influence on mortality in this cohort in univariate analysis. Mean age at entry was 50+/-13 years (mean+/-SD). During an average follow-up of 112+/-53 months, 107 fatal events occurred. Among them, 46 were of cardiovascular origin. PWV was significantly associated with all-cause and cardiovascular mortality in a univariate model of logistic regression analysis (odds ratio for 5 m/s PWV was 2.14 [95% confidence interval, 1.71 to 2.67, P<0.0001] and 2.35 [95% confidence interval, 1.76 to 3.14, P<0.0001], respectively). In multivariate models of logistic regression analysis, PWV was significantly associated with all-cause and cardiovascular mortality, independent of previous cardiovascular diseases, age, and diabetes. By contrast, pulse pressure was not significantly and independently associated to mortality. This study provides the first direct evidence that aortic stiffness is an independent predictor of all-cause and cardiovascular mortality in patients with essential hypertension.

Pulse pressure is a stronger predictor of cardiovascular events than systolic or diastolic blood pressure in large cohorts of French and North American patients. However, its influence on stroke is controversial. Large-artery stiffness is the main determinant of pulse pressure. The influence of arterial stiffness on the occurrence of stroke has never been demonstrated. Our aim was to establish the relationship between aortic stiffness and stroke death in hypertensive patients. We included, in a longitudinal study, 1715 essential hypertensive patients who had a measurement of arterial stiffness at entry (ie, between 1980 and 2001) and no overt cardiovascular disease or symptoms. Mean follow-up was 7.9 years. At entry, aortic stiffness was assessed from the carotid-femoral pulse wave velocity. A Cox proportional hazard regression model was used to estimate the relative risk (RR) of stroke and coronary deaths. Mean+/-SD age at entry was 51+/-13 years. Twenty-five fatal strokes and 35 fatal coronary events occurred. Pulse wave velocity significantly predicted the occurrence of stroke death in the whole population. There was a RR increase of 1.72 (95% CI, 1.48 to 1.96; P<0.0001) for each SD increase in pulse wave velocity (4 m/s). The predictive value of pulse wave velocity remained significant (RR=1.39 [95% CI, 1.08 to 1.72]; P=0.02) after full adjustment for classic cardiovascular risk factors, including age, cholesterol, diabetes, smoking, mean blood pressure, and pulse pressure. In this population, pulse pressure significantly predicted stroke in univariate analysis, with a RR increase of 1.33 (95% CI, 1.16 to 1.51) for each 10 mm Hg of pulse pressure (P<0.0001) but not after adjustment for age (RR=1.19 [95% CI, 0.96 to 1.47]; P=0.10). This study provides the first evidence, in a longitudinal study, that aortic stiffness is an independent predictor of fatal stroke in patients with essential hypertension.