Aortic Pulse Wave Velocity as a Biomarker in Chronic Dialysis Patients

Abstract

Cardiovascular mortality is considered the main cause of death in patients receiving dialysis and is 10–20 times higher in such patients than in the general population. A high percentage of all cardiovascular mortality diseases are associated with stiffening of the arteries, a direct consequence of atherosclerosis. Increased central arterial stiffening is a hallmark of the aging process and consequence of many disease states, such as diabetes, atherosclerosis, and chronic renal compromise. Accelerated arteriosclerosis is a major risk to long-term survivors on maintenance hemodialysis.

Measuring of the pulse wave velocity provides useful information regarding the mechanical properties of the arterial tree and can be used to assess the stiffness and endothelial function. From all the different methods to assess arterial stiffness, carotid to femoral pulse wave velocity has emerged as the gold standard method. Two Doppler waves are recorded transcutaneously at the base of the neck for the right common carotid artery and over the right common femoral artery. After that, the Doppler waves are identified and their time delay diversity is measured simultaneously with electrocardiography. Time delay (transition time, ΔT) is the time from the R wave to the foot of the carotid or femoral Doppler waveform.

There is a high prevalence of increased pulse wave velocity in a relatively young hemodialysis patient population. Vascular stiffening likely begins much earlier and progresses more rapidly in hemodialysis patients. Accelerated arteriosclerosis is a major risk to long-term survivors on maintenance hemodialysis. The pulse wave velocity measured at baseline was markedly higher in chronic hemodialysis patients than in general population patients, with a greater than twofold higher annual increase. In the general population group, only factors associated with the progression of arterial stiffness in the elderly were evident (traditional risk factors), but in chronic kidney disease patients, arterial stiffness (i.e. pulse wave velocity) is accelerated due to synergism between age and traditional risk factors plus factors related to renal comorbidity (nontraditional risk factors). Patients with end stage renal disease face a particularly high risk of cardiovascular disease and total mortality. It is now known that pulse wave velocity, C-reactive protein and serum albumin are strongly and independently predictive of outcome in chronic hemodialysis patients. Whether enhanced arterial stiffness is a risk factor contributing to the development of cardiovascular disease or a marker of established cardiovascular disease is a matter of debate. The pulse wave velocity is a strong independent predictor of over-all and cardiovascular mortality with high-level performance values, assessed by simple, indirect, reproducible and noninvasive evaluation of regional arterial stiffness.