title: Impact of seasonality and air pollutants on carotid-femoral pulse wave velocity and wave reflection in hypertensive patients.
abstract: OBJECTIVE
  The effects of seasonality on blood pressure (BP) and cardiovascular (CV) events are well established, while the influence of seasonality and other environmental factors on arterial stiffness and wave reflection has never been analyzed. This study evaluated whether seasonality (daily number of hours of light) and acute variations in outdoor temperature and air pollutants may affect carotid-femoral pulse wave velocity (PWV) and pressure augmentation.
  
  
  METHODS
  731 hypertensive patients (30-88 years, 417 treated) were enrolled in a cross-sectional study during a 5-year period. PWV, central BP, Augmentation Index (AIx) and Augmentation Pressure (AP) were measured in a temperature-controlled (22-24°C) room. Data of the local office of the National Climatic Data Observatory were used to estimate meteorological conditions and air pollutants (PM10, O3, CO, N2O) exposure on the same day.
  
  
  RESULTS
  PWV (mean value 8.5±1.8 m/s) was related to age (r = 0.467, p<0.001), body mass index (r = 0.132, p<0.001), central systolic (r = 0.414, p<0.001) and diastolic BP (r = 0.093, p = 0.013), daylight hours (r = -0.176, p<0.001), mean outdoor temperature (r = -0.082, p = 0.027), O3 (r = -0.135, p<0.001), CO (r = 0.096, p = 0.012), N2O (r = 0.087, p = 0.022). In multiple linear regression analysis, adjusted for confounders, PWV remained independently associated only with daylight hours (β = -0.170; 95% CI: -0.273 to -0.067, p = 0.001). No significant correlation was found between pressure augmentation and daylight hours, mean temperature or air pollutants. The relationship was stronger in untreated patients and women. Furthermore, a positive, independent association between O3 levels and PWV emerged in untreated patients (β: 0.018; p = 0.029; CI: 0.002 to 0.034) and in women (β: 0.027; p = 0.004; CI: 0.009 to 0.045).
  
  
  CONCLUSIONS
  PWV showed a marked seasonality in hypertensive patients. Environmental O3 levels may acutely reduce arterial stiffness in hypertensive women and in untreated patients.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Di Pilla
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Bruno
authors.affiliation: Institute of Clinical Physiology, National Research Council, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Stea
authors.affiliation: Institute of Biometeorology, National Research Council, Florence, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Massetti
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Taddei
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Ghiadoni
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.
authors.forename: Pietro Amedeo
authors.initials: PA
authors.lastname: Modesti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D001794:Blood Pressure / Q000187:drug effects; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D063177:Pulse Wave Analysis; D012621:Seasons
chemical_list: D000393:Air Pollutants