Nocturnal blood pressure decrease is associated with increased regional cerebral blood flow in patients with a history of ischemic stroke

Impact of night-time blood pressure on cerebral white matter hyperintensity in elderly hypertensive patients

AIM

Cerebral white matter hyperintensity (WMH) is highly prevalent in the elderly population, and increases the risk of dementia and stroke. We investigated the relationship between ambulatory blood pressure monitoring levels and quantitatively measured WMH volumes among elderly hypertensive patients with well-controlled blood pressure (BP) to re-evaluated effective hypertension management methods to prevent the progression of WMH.

METHODS

Participants comprised 84 hypertensive patients aged between 65 and 75 years without symptomatic heart failure, ischemic heart disease, atrial fibrillation, stroke or cognitive dysfunction.

RESULTS

Linear regression analysis showed that office BP was not associated with WMH volume increases. Raised night-time systolic BP (P = 0.013) were associated with greater WMH volumes during ambulatory blood pressure monitoring. To clarify the effect of asleep systolic BP on WML volume, we then classified patients into two systolic BP groups as follows: <125 mmHg (n = 47) and ≥125 mmHg (n = 37). Baseline characteristics were almost similar in both groups, except the dipper type of circadian BP variation was significantly common in the group with night-time systolic BP <125 mmHg. However, WMH volume was greater in the group with night-time systolic BP ≥125 mmHg than that in the <125 mmHg group (9.0 ± 8.4 mL vs 4.1 ± 4.3 mL, P = 0.015).

CONCLUSION

Higher night-time systolic BP levels were observed to contribute greater WMH volumes in elderly hypertensive patients. To prevent the progression of WMH, controlling BP on the basis of ambulatory blood pressure monitoring is important.

Secondary Stroke Prevention: Improving Diagnosis and Management with Newer Technologies

Treatment of hypertension, diabetes, high cholesterol, smoking cessation, and healthy lifestyle have all contributed to the decline in the incidence of vascular disease over the last several decades. Patients who suffer an acute stroke are at a high risk for recurrence. Introduction of newer technologies and their wider use allows for better identification of patients in whom the risk of recurrence following an acute stroke may be very high. Traditionally, the major focus for diagnosis and management has focused on patient history, examination, imaging for carotid stenosis/occlusion, and detection of AF and paroxysmal AF (PAF) with 24-48 h cardiac monitoring. This review focuses on the usefulness of three newer investigative tools that are becoming widely available and lead to better prevention. Continuous ambulatory blood pressure measurements for 24 h or longer and 3D Doppler measures of the carotid arteries provide key useful information on the state of vascular health and enhance our ability to monitor the response to preventive therapies. Furthermore, the detection of PAF can be significantly improved with prolonged cardiac monitoring for 3 weeks or longer, enabling the initiation of appropriate prevention therapy. This review will focus on the potential impact and importance of these emerging technologies on the prevention of recurrent stroke in high-risk patients.

The structural and functional consequences of diurnal variations in blood pressure in treated patients with hypertensive cerebrovascular disease

BACKGROUND

Although hypertension is known to cause brain damage and cognitive impairment, epidemiological studies suggest that lower blood pressure (BP) in patients with established cerebrovascular disease is associated with more rapid cognitive decline. We investigated the relationship between 24-h ambulatory blood pressure (ABP) measurements, cerebrovascular disease load and cognitive performance in patients with hypertensive cerebrovascular disease.

METHODS

Eighty-eight patients (mean age 65+9 years) with hypertensive cerebrovascular disease on MRI were recruited. BP was controlled optimally. ABP monitoring, quantitative MRI analysis of white matter lesion (WML) volume and executive cognitive function tests were performed. The relationships between ABP variables, WML volume and executive test performance were examined using regression analyses to adjust for age, sex, vascular risk profile and premorbid intelligence.

RESULTS

Patients had a mean daytime ABP of 96+10 mmHg and mean night-time ABP of 88+11 mmHg (P = 0.001). Median WML volume was 8464 mm3. There were no significant associations between ABP variables and supratentorial WML volumes. Infratentorial WML volume correlated negatively with night-time mean BP (r = -0.6, P = 0.002) and positively with nocturnal dipping (r = 0.6, P = 0.002). Higher night-time mean BP was an independent predictor of reduced infratentorial WML volume (R2: 0.460, P = 0.008).Infratentorial WML volume correlated with impairments of phonemic verbal fluency (r = 0.5, P < 0.001) and choice reaction time (r = 0.7, P < 0.005).

CONCLUSION

Physiological falls in nocturnal BP may be associated with increased infratentorial WML volume and cognitive dysfunction in optimally controlled hypertensive patients with cerebrovascular disease.

The relationship between nighttime dipping in blood pressure and cerebral hemodynamics in nonstroke patients

Inadequate dipping in nighttime blood pressure (BP) is associated with cerebrovascular disease. The authors aimed to determine whether inadequate nocturnal dipping was associated with abnormalities in cerebrovascular hemodynamics in individuals without stroke. Participants in this study underwent 24-hour ambulatory BP monitoring followed by morning transcranial Doppler measurements of blood flow velocities (BFVs) in the middle cerebral artery during supine rest, head-up tilt, hypocapnia, and hypercapnia. Nighttime BP decline by <10% was considered nondipping. Of the 102 nonstroke participants (mean age, 53.6 years), 35 (34%) were dippers. Although nondippers had similar BFV and cerebrovascular resistance (CVR) while supine, they had a lower BFV (P=.04) and greater CVR (P=.02) during head-up tilt compared with dippers. Moreover, greater nighttime dipping in both systolic BP (P=.006) and diastolic BP (P=.03) were associated with higher daytime BFV and lower CVR (P=.01 for systolic BP; P=.02 for diastolic BP). Inadequate nocturnal BP dipping is associated with lower daytime cerebral blood flow, especially during head-up tilt.

Drug therapy for the secondary prevention of stroke in hypertensive patients: current issues and options

Hypertension is the major risk factor for ischaemic and haemorrhagic clinical strokes as well as for silent brain infarcts with a continuous association between both systolic and diastolic blood pressures. Epidemiological data highlight the increasing burden to come over the next decades. Without any doubt, antihypertensive treatment is the most important therapy to reduce the risk of stroke by approximately 30-40%. International guidelines recommend antihypertensive treatment for primary prevention with evidence level A. Recurrent strokes or transient ischaemic attack (TIA) are an important practical, clinical and economic problem, and have a major impact on the development of vascular dementia. All stroke patients and patients with TIA have to be regarded as very high-risk patients. Hypertension increases the risk of recurrent strokes. Only limited data directly address the role of blood pressure treatment among individuals with stroke or TIA. There is a general lack of definitive data regarding when to start antihypertensive treatment in the initial phase, and treatment of hypertension in the acute period after stroke is still under debate. Experimental and clinical data suggest that reducing the activity of the renin-angiotensin aldosterone system (RAAS) may have beneficial effects beyond the lowering of blood pressure. There is increasing evidence of cerebroprotective effects for medication influencing the RAAS, such as angiotensin receptor antagonists or ACE inhibitors. The MOSES study showed for the first time superiority of an angiotensin receptor antagonist compared with a calcium channel antagonist in antihypertensive treatment for secondary stroke prevention. Optimal blood pressure range in secondary prevention seems to be 120-140/80-90 mm Hg, but questions about a J- or U-shaped curve are still not answered sufficiently. The effects of additional antihypertensive treatment in the evening for stroke patients with 'non-dipping' blood pressure need to be investigated.Currently, the most important goal in primary and secondary prevention of stroke is a strict normotensive blood pressure control. Antihypertensive treatment is recommended for both prevention of recurrent stroke and prevention of other vascular events in individuals who have had an ischaemic stroke or TIA (class I, level of evidence A). Many open questions remain and funding of stroke research needs to be increased in the near future.