Faculty Collaboration Database

Relation of season and temperature to endothelium-dependent flow-mediated vasodilation in subjects without clinical evidence of cardiovascular disease (from the Framingham Heart Study). Am J Cardiol 2007 Aug 01;100(3):518-23

Date

07/31/2007

Pubmed ID

17659939

Pubmed Central ID

PMC1994775

DOI

10.1016/j.amjcard.2007.03.055

Scopus ID

2-s2.0-34547122236 (requires institutional sign-in at Scopus site)   68 Citations

Abstract

Multiple studies have documented an increased incidence of cardiovascular events in the winter, but the pathophysiologic mechanisms remain incompletely understood. It was hypothesized that brachial flow and flow-mediated dilation (FMD) would vary by season and temperature. Season and temperature were related to ultrasonic brachial artery endothelium-dependent FMD% (n = 2,587), baseline flow velocity, and maximal reactive hyperemia (n = 1,973) in the Framingham Offspring Cohort (mean age 61 +/- 10 years, 53% women). Outdoor temperatures were obtained from National Climate Data Center records for Bedford, Massachusetts (about 14 miles from the testing site), and the examination room temperature was measured. In multivariate models, FMD% was highest in summer and lowest in winter (3.01 +/- 0.09% vs 2.56 +/- 0.10%, respectively, p = 0.02 for differences across all 4 seasons). FMD% was highest in the warmest and lowest in the coldest outdoor-temperature quartiles. In stepwise models adjusting for risk factors and selecting among season, outdoor temperature, and room temperature, FMD% was associated with season (p = 0.02); temperature did not enter the model. In contrast, hyperemic flow velocity was significantly lower for cooler and higher for warmer room temperatures (p = 0.02 overall); season did not enter the model. Season and outdoor and room temperature were each retained in a stepwise model of baseline flow velocity (p <0.0001, p = 0.02, and p <0.0001, respectively). In conclusion, a significant association was observed between season and FMD%. Microvascular vasodilator function, as reflected by hyperemic flow velocity, was more strongly related to temperature than season. Endothelial dysfunction may be 1 of the mechanisms influencing seasonal variation in cardiovascular events.

Author List

Widlansky ME, Vita JA, Keyes MJ, Larson MG, Hamburg NM, Levy D, Mitchell GF, Osypiuk EW, Vasan RS, Benjamin EJ

Author

Michael E. Widlansky MD Associate Director, Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Blood Flow Velocity
Brachial Artery
Endothelium, Vascular
Female
Humans
Hyperemia
Male
Middle Aged
Reference Values
Seasons
Temperature
Vasodilation