Comparison of arterial stiffness, vagosympathetic activity and risk factors in subjects with exercise hypertension and normotension

• Main Authors: Yu-Lin Chen, 陳育麟
• Other Authors: Mei-Wun Tsai
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/42855745824753640969

碩士 === 國立陽明大學 === 物理治療學系暨研究所 === 94 === Background and purpose : Hypertension is a prevalent worldwide problem. Besides the major risk factors, arterial stiffness and autonomic nervous system (ANS) dysfunction have also important roles on the pathophysiology of hypertension. Exercise hypertension, an exaggerated rising of blood pressure (BP) during physical activity, has been found to be a strong predictor of cardiovascular mortality and may be an early marker of essential hypertension. However, the exact mechanism of exercise hypertension is unclear. The purpose of this study was to compare the differences of arterial stiffness, vagosympathetic activity and risk factors in subjects with exercise hypertension, resting hypertension and normotension. Methods : This was an exploratory cross-sectional study. Sixty-five men (50.6±6.5 years old) with resting BP below 160/100 mmHg were included. Those who had the history of chronic diseases, exercise contraindications and taking any medicines affecting BP or ANS were excluded. All subjects received noninvasive arterial stiffness test, submaximal exercise test, heart rate variability test (HRV) at rest and under mental stress, and were interviewed the related risk factors by questionnaires. All subjects were grouped as resting hypertension (BP≧140/90mmHg, n=10), or not (BP<140/90mmHg, n=55), exercise hypertension (SBP≧200mmHg, n=40), or not (SBP<200mmHg, n=25), and also grouped into normotension (n=25), only exercise hypertension (n=30), or both resting and exercise hypertension (n=10). Results : Thirty of fifty-five subjects (54.5%) with normal resting BP appeared exercise hypertension, while all subjects with resting hypertension had exercise hypertension. Subjects in the resting hypertension group had higher proportion of having hypertensive family history and high-sodium diet, and higher brachial-ankle pulse wave velocity (baPWV) compared to those without resting hypertension (p<0.05). Subjects with exercise hypertension had higher cardiovascular risk factor score, exercise SBP slope, and baPWV compared to those without exercise hypertension (p<0.05). Subjects with both resting and exercise hypertension had higher proportion of hypertensive family history, high-sodium diet, the cardiovascular risk factor score, exercise SBP slope and baPWV than those with only exercise hypertension or normotension. In the results of multiple regression, the higher resting SBP were association with having hypertensive family history and the higher baPWV and cardiovascular risk factor score (adjusted R2=43%). Exercise SBP was significantly associated with cardiovascular risk factor score, baPWV and the change of HRV in normalized low frequency power (LF%) under mental stress and at rest (adjusted R2=32%). In logistic regression, subjects with higher baPWV (OR:1.005, 95%CI:1.001-1.010) and having of hypertension family history (OR:11.4, 95%CI:1.9-68.8) had higher risk to have resting hypertension (adjusted R2=35%). Subjects with exercise hypertension had higher cardiovascular risk factor score (OR:1.7, 95%CI:1.2-2.6), baPWV (OR:1.004, 95%CI:1.001-1.008), and lower change of HRV in the mean of R-R intervals under mental stress and at rest (OR:0.991, 95%CI:0.98-0.999), R2=41%. Conclusion : High prevalence of exercise hypertension could be found in the middle-aged men with normal resting BP. Cardiovascular risk factor score and baPWV were associated with both resting and exercise hypertension. Hypertensive family history was a major risk factor of resting hypertension, but heart rate variability at rest and under mental stress affected exercise hypertension more. Therefore, exercise hypertension may be an early sign of resting hypertension but some different underlying mechanisms may exist between both hypertension. Our results may highlight the clinical significance of exercise hypertension in the early health screening program.