Pulse wave velocity

Value of Pulse Wave Velocity.

Posted by

0


Cardiovascular disease is a major cause of death in patients with a kidney transplant. This should be no surprise as many of these patients get transplanted with a significant history of traditional as well as non-traditional risk factors related to CKD or wait-time on dialysis.  I encourage all my patients to exercise and stay active in the first year after transplant, but don’t know exactly how much or what type of exercise is required to provide an unclear amount of cardiovascular benefit.

In ESRD patients, aerobic training has been shown to reduce the pulse wave velocity (PWV), which is a non-invasive measure of arterial stiffness that has been positively correlated with mortality in kidney transplant recipients.  Several small studies have found that aerobic training or aerobic plus resistance exercise training improves cardiorespiratory fitness, quality of life, and hand strength, but none have evaluated the impact on cardiovascular measures. However, a new study in AJKD by Greenwood et al measured the effect of three exercise programs on pulse wave velocity, cardiorespiratory fitness, and serum inflammatory markers. This trial randomized 60 adult kidney transplant recipients within the first year of transplant to one of three arms: an individualized aerobic training program, a resistance-training program, or usual care. The intervention groups were both required to attend twice-weekly outpatient exercise and education sessions, and to also undergo a home-based exercise session once a week for a total of 12 weeks.  The study measured PWV, VO2peak and serum inflammatory markers before and after the 12-week period.

Copyright: vectomart / 123RF Stock Photo

Compared to usual care, the mean difference in PWV was significantly lower at 12 weeks in patients who completed either the aerobic training or resistance training (both with P<0.001).  Both exercise interventions were also associated with significant improvements in the relative and absolute VO2peak. There were no significant differences in inflammatory markers between the three groups. Overall, this suggests that a supervised exercise program using either aerobic or resistance training improves cardiorespiratory fitness and reduces arterial stiffness. One caveat to this conclusion is that both exercise intervention groups had 7 participants (35% of each arm) who were lost to follow up because they needed to return to work and presumably could not attend the outpatient sessions. This suggests that the exercise program required to meet these outcomes may be too cumbersome for patients who are further from surgery and returning to work. The analysis only included patients who completed the trial, and exclusion of the dropouts may have biased the results. Despite the small sample sizes in this pilot study, it seems that in the short term, adhering to a rigorous exercise program reduces the PWV and improves fitness in kidney transplant recipients. It is unknown if the PWV returned to baseline in those patients who stop exercising. An intense 12-week regimen seems to be beneficial, but we should also think about exercise interventions that are sustainable for the long-term as well.

Structural and biochemical characteristics of arterial stiffness in patients with atherosclerosis and in healthy subjects.

Posted by

0


Arterial stiffness is an independent predictor of vascular morbidity and mortality in patients with atherosclerosis. Angiographic score (ASc) reflects severity of atherosclerosis in patients with peripheral arterial disease (PAD). Osteopontin (OPN) and oxidized low-density lipoprotein (oxLDL) are involved in the pathogenesis of atherosclerosis. The aim of the present study was to evaluate the association between arterial stiffness, ASc, serum OPN and oxLDL in patients with symptomatic PAD, and in clinically healthy subjects. We studied 79 men with symptomatic PAD (mean age 64±7 years) and 84 healthy men (mean age 63±8 years). Calculation of the ASc was based on severity and location of atherosclerotic lesions in the arteries of the lower extremities. Aortic pulse wave velocity (aPWV) was evaluated by applanation tonometry using the Sphygmocor device. Serum OPN and oxLDL levels were determined by enzyme-linked immunosorbent assay. The aPWV (10±2.4 VS. 8.4±1.7 (m s−1); P<0.001), OPN (75 (62.3–85.8) VS. 54.8 (47.7–67.9) (ng ml−1); P<0.001) and oxLDL (67 (52.5–93.5) VS. 47.5 (37–65.5); P<0.001) were different for the patients and for the controls. In multiple regression models, aPWV was independently determined by ASc, log-OPN, log-oxLDL and estimated glomerular filtration rate in the patients (R2=0.44; P<0.001) and by log-OPN, log-oxLDL, age and heart rate in the controls (R2=0.38; P<0.001). The independent relationship of a PWV with serum levels of OPN and oxLDL in the patients with PAD and in the controls indicates that OPN and oxLDL might influence arterial stiffening in patients with atherosclerosis and in clinically healthy subjects.

Source: Hypertension Research/nature.

24-h ambulatory recording of aortic pulse wave velocity and central systolic augmentation: a feasibility study.

Posted by

1


We assessed the feasibility of ambulatory pulse wave analysis by comparing this approach with an established tonometric technique. We investigated 35 volunteers (45.6 years; 51.0% women) exclusively at rest (R study) and 83 volunteers (49.9 years; 61.4% women) at rest and during daytime (1000–2000 h) ambulatory monitoring (R+A study). We recorded central systolic (cSP), diastolic (cDP) and pulse (cPP) pressures, augmentation index (cAI) and pulse wave velocity (PWV) by brachial oscillometry (Mobil-O-Graph 24h PWA Monitor) and radial tonometry (SphygmoCor). We applied the Bland and Altman’s statistics. In the R study, tonometric and oscillometric estimates of cSP (105.6 vs. 106.9 mm Hg), cDP (74.6 vs. 74.7 mm Hg), cPP (31.0 vs. 32.1 mm Hg), cAI (21.1 vs. 20.6%) and PWV (7.3 vs. 7.0 m s−1) were similar (P0.11). In the R+A study, tonometric vs. oscillometric assessment yielded similar values for cSP (115.4 vs. 113.9 mm Hg; P=0.19) and cAI (26.5 vs. 25.3%; P=0.54), but lower cDP (77.8 vs. 81.9 mm Hg; P<0.0001), so that cPP was higher (37.6 vs. 32.1 mm Hg; P<0.0001). PWV (7.9 vs. 7.4 m s−1) was higher (P=0.0002) on tonometric assessment. The differences between tonometric and oscillometric estimates increased (P0.004) with cSP (r=0.37), cAI (r=0.39) and PWV (r=0.39), but not (P0.17) with cDP (r=0.15) or cPP (r=0.13). Irrespective of measurement conditions, brachial oscillometry compared with an established tonometric method provided similar estimates for cSP and systolic augmentation, but slightly underestimated PWV. Pending further validation, ambulatory assessment of central hemodynamic variables is feasible.

Source: Hypertension Research/nature.