Vascular Damage in Exaggerated Morning Surge in Blood Pressure

Abstract

R ecent clinical studies demonstrated that an exaggerated morning blood pressure (BP) surge is a risk for cardiovascular events, such as ischemic and hemorrhagic stroke. [1][2][3] Simultaneously, neurohumoral factors and various cardiovascular risk factors are exaggerated in the morning. Although the precise molecular mechanisms remain unclear, exaggerated morning BP surge has been closely associated with other cardiovascular risk factors potentiated in the morning (Figure). The main mechanisms of morning BP surge and associated neurohumoral activation on cardiovascular disease consist of progression of cardiovascular remodeling and atherosclerosis, as well as direct effects of BP surges that may trigger cardiovascular events.An exaggerated morning BP surge may advance vascular remodeling from the larger arteries to the small resistance vessel through increased mechanical pressure and shear stress of an exaggerated fluctuation of blood flow on the vessel wall. In hypertensive patients, morning BP surge and time of morning BP variability in the morning were significantly correlated with increased carotid intima-media thickness, and these associations were independent of 24-hour BP levels. 4 On the other hands, increased stiffness of large arteries increases BP variability through impaired baroreceptor sensitivity. This increase in BP variability is pronounced particularly in the morning, when compared with the other periods, 5 leading to cardiac hypertrophy. 6 In addition, small artery disease may also be associated with exaggerated morning BP surge. In our previous study on elderly hypertensive patients, silent cerebral infarcts, assessed by brain MRI, were significantly associated with exaggerated morning BP surge. 7 This association was prominent between multiple cerebral infarcts and morning BP surge and appeared to depend on ␣-adrenergic sympathetic activity. The reactivity of morning BP surge depends on the ␣-adrenergic vasoconstrictor response of small resistance vessel, and it may be closely related to remodeling of the small vessel. Thus, morning BP surge and vascular remodeling of various arterial sizes could form a vicious cycle of cardiovascular risk.As shown in the Figure, the morning BP surge also seems to have some role in the initial stage and the progression of atherosclerosis. In the model of sinoaortic denervation rat, which exhibits the marked BP variation, the neointimal formation after vascular injury was significantly increased. 8 In healthy subjects without atherosclerotic disease, flow-mediated vasodilation, which reflects endothelial function, was reduced early in the morning. Reduced endothelial function could contribute to the high BP reactivity in the morning. 9 In addition, because activity of the sympathetic nervous system and renin-angiotensin-aldosterone system is the highest in the morning, the impact of exaggerated BP variability in the morning to lead to endothelial cell damage and subsequent atherosclerosis would be greater than in other periods of the day.In this issue, Marfe...

Association Between Ambulatory Systolic Blood Pressure During the Day and Asymptomatic Intracranial Arterial Stenosis

“…32 Under circumstances of enhanced inflammation and oxidative stress, 31,32 increased activity of platelet aggregation, 33 and greater activity of the sympathetic and renin-angiotensin-aldosterone systems in the morning, the effect of morning BP on endothelial cells and subsequent atherosclerosis might be greater than at other periods of the day. 34 However, patients with intracranial atherosclerosis may have stiffer arteries 9 and hence more pronounced morning BP surge. 24 We acknowledge that our study has some limitations.…”

Short-term and long-term repeatability of the morning blood pressure in older patients with isolated systolic hypertension

“…The morning surge is the rise in BP on awakening and might be a predictor of cardiovascular complications [1][2][3][4][5]. Japanese hypertensive patients with mean age of 72 years had a higher risk of multiple brain infarcts and stroke if the morning surge in systolic BP was above the 90th percentile [2], or if the difference of systolic BP between morning and evening was above the top quartile (>20 mmHg) [6].…”

Seasonal Influence on Blood Pressure in Elderly Normotensive Subjects

“…A rapid increase in BP in the morning, referred to as a morning surge, is thought to be related to cardiovascular disease and cerebrovascular disease (20)(21)(22)(23)(24)(25). We observed a difference between pre-wake-up-time SBP and wake-up-time SBP, and the morning surge was greater in the cold seasons than in the warm seasons.…”