Blood pressure variability and prognosis in acute ischemic stroke with vascular compression on the rostral ventrolateral medulla (RVLM)

Effects of temperature and humidity on cerebrovascular disease hospitalization in a super-aging society

Weather conditions influence the incidence of cardiovascular disease. However, few studies have investigated the association between weather temperature and humidity and cerebrovascular disease hospitalizations in a super-aging society. We included 606,807 consecutive patients with cerebrovascular disease admitted to Japanese acute-care hospitals between 2015 and 2019. The primary outcome was the number of cerebrovascular disease hospitalizations per day. Multilevel mixed-effects linear regression models were used to estimate the association of mean temperature and humidity, 1 day before hospital admission, with cerebrovascular disease hospitalizations, after adjusting for air pollution, hospital, and patient demographics. Lower mean temperatures and humidity < 70% or humidity ≧ 70% are associated with an increased incidence of cerebrovascular disease hospitalization (coefficient, - 1.442 [- 1.473 to - 1.411] per °C, p < 0.001, coefficient, - 0.084 [- 0.112 to - 0.056] per%, p < 0.001, and coefficient, 0.136 [0.103 to 0.168] per %, p < 0.001, respectively). Lower mean temperatures and extremely lower or higher humidity are associated with an increased incidence of cerebrovascular disease hospitalization in a super-aging society.

Effects of vascular compression on the rostral ventrolateral medulla for blood pressure variability in stroke patients

BACKGROUNDS

Vascular compression of the rostral ventrolateral medulla (RVLM) has been associated with hypertension or blood pressure (BP) variability. For acute ischemic stroke patients, increased BP variability may cause poor functional outcomes. We tested the hypothesis that RVLM compression was associated with increased BP variability or stroke outcome in acute ischemic stroke patients.

METHODS

Acute ischemic stroke patients (n = 622) with 24-h ambulatory BP monitoring during the subacute phase of stroke (median 9 days from onset) were retrospectively studied. Variability in BP was evaluated with the SD and coefficient of variation of SBP and DBP. The morning surge was also evaluated. The presence of RVLM compression was evaluated using time-of-flight three-dimensional MRI. A poor outcome was defined as a modified Rankin Scale score of 3-6 at 3 months.

RESULTS

Patients with RVLM compression (n = 213) had significantly higher 24-h SBP mean, 24-h SBP SD, 24-h SBP coefficient of variation, 24-h DBP mean, 24-h DBP SD, and 24-h DBP coefficient of variation values and a higher prevalence of morning surge than those without (n = 409). Multiple regression analysis revealed that RVLM compression was associated with increased SBP variability, DBP variability, and morning surge. Despite the significant association between RVLM compression and BP variability, RVLM compression was not associated with poor stroke outcome.

CONCLUSION

Although RVLM compression was closely associated with BP variability in the subacute ischemic stroke phase, an effect of RVLM compression on stroke outcome was not observed.

Increased blood pressure variability during the subacute phase in patients with ischemic stroke presenting with a low ankle-brachial index

AIM

This study aimed to evaluate the associations of blood pressure (BP) variability in patients with ischemic stroke during the subacute phase using ambulatory blood pressure monitoring and the ankle-brachial index (ABI).

METHODS

We retrospectively examined 831 consecutive patients (women 44.8%, mean age 76 ± 12 years) with acute ischemic stroke who underwent 24-h ambulatory blood pressure monitoring during the subacute phase of stroke (median 9 days from onset) and an ABI examination. BP variability was evaluated by assessing the standard deviation and coefficient of variation of systolic BP and diastolic BP. A low ABI was defined as an ABI <0.9.

RESULTS

Of the 831 patients, 201 (24.2%) had a low ABI. Older age, lower body mass index, diabetes mellitus, chronic kidney disease, atrial fibrillation and a higher National Institutes of Health Stroke Scale score at admission were independently associated with a low ABI. The patients with a low ABI had a higher mean 24-h diastolic BP, higher standard deviation of both BP measurements (systolic BP and diastolic BP) and a higher coefficient of variation in both BP measurements than those with a higher ABI. According to the multivariable linear regression analysis, a low ABI was independently associated with increased BP variability (a high standard deviation or coefficient of variation of both BP measurements) after adjusting for baseline confounders.

CONCLUSIONS

A low ABI was associated with increased BP variability during the subacute ischemic phase. Geriatr Gerontol Int 2020; 20: 448-454.

Increased blood pressure variability during the subacute phase of ischemic stroke is associated with poor functional outcomes at 3 months

Thus far, it is well known that increased blood pressure variability may exacerbate stroke outcomes. Blood pressure in the acute phase would be influenced by both reactive hypertension to stroke and intrinsic blood pressure reactivity. Thus, we aimed to evaluate the association between blood pressure variability and outcomes at 3 months using ambulatory blood pressure monitoring in ischemic stroke patients in the subacute phase after reactive hypertension subsided. We retrospectively examined 626 consecutive patients with acute ischemic stroke who underwent 24-hour ambulatory blood pressure monitoring during the subacute phase of stroke (median, 9 days from onset). The variability in blood pressure was evaluated by assessing the standard deviation and coefficient of variation of systolic and diastolic blood pressure. The primary outcome was functional status at 3 months. A poor outcome was defined as a modified Rankin scale score of 3 or more and a good outcome as 2 or less. We assessed the functional outcome at 3 months in 497 patients (79.4%). The mean systolic and diastolic blood pressure levels were not associated with functional outcome. The multivariable analysis revealed that increases in the standard deviations of systolic and diastolic blood pressure, coefficient of variation of diastolic blood pressure, and morning blood pressure surge were associated with poor outcome. Blood pressure variability during the subacute phase of ischemic stroke can be a useful prognostic indicator of poor functional outcome at 3 months in patients with acute ischemic stroke.

Blood pressure characteristics in patients with acute basilar artery occlusion undergoing endovascular thrombectomy

Acute basilar artery occlusion (BAO) is a rare but potentially life-threatening neurological condition. While endovascular therapy (EVT) has been shown to improve outcome, there is limited knowledge about prognostic factors beyond early recanalization. We studied whether blood pressure (BP) exceeds or falls below suggested thresholds during intervention and whether these changes are associated with complications and outcome. BP measurements mostly with one-minute intervals were available in 39 patients. An individual systolic blood pressure (SBP) reference value was defined as the median of the first five intra-procedural measurements. Half of the patients (51.3%) received drugs for BP augmentation and two a BP lowering drug (5.1%). Thrombolysis in cerebral infarction grade 2b and 3 (TICI) was achieved in 29 (74.4%) and 23 patients (58.9%) had good outcome at three months. We observed a continuous intra-procedural increase of median SBP (+11%) and mean arterial pressure (MAP, +10%, both p < 0.001), and a unique temporal pattern of intermittent peaks and troughs. Successful recanalization was more common in patients whose intra-procedural duration with SBP under 140 mmHg was shorter (p = 0.009). Patients with isolated tip of basilar artery (TBA) occlusion had significantly more BP excursion of 20% below the reference SBP and required more frequent use of sympathomimetic drugs compared to vertebrobasilar occlusion (p = 0.008 and p = 0.041, respectively). Brain hemorrhage was more prevalent in patients who experienced SBP excursions at least 20% above the individual reference value (p = 0.038) and a longer duration of time spent with SBP above 180 mmHg (p = 0.029). Patients with higher pre-procedural mean SBP had a greater chance of a good outcome (p = 0.03). This study using high resolution BP monitoring suggests a relationship between intra-procedural BP characteristics and recanalization, hemorrhagic complications and outcome in patients receiving EVT for acute posterior circulation cerebrovascular syndromes. Differences with regard to BP regulation during recanalization therapy for vertebrobasilar and TBA occlusion deserves further attention.

Dynamic cerebral autoregulation measurement using rapid changes in head positioning: experiences in acute ischemic stroke and healthy control populations

The ideal technique for dynamic cerebral autoregulation (dCA) assessment in critically ill patients should provide considerable variability in blood pressure (BP) but without the need for patient cooperation. We proposed using rapid head positioning (RHP) over spontaneous BP fluctuations for dCA assessment in patients with acute ischemic stroke (AIS). Cerebral blood velocity (transcranial Doppler), beat-to-beat BP (Finometer), and end-tidal CO2 (capnography) were recorded during 5-min baseline and RHP in 16 controls (8 women and 8 men, mean age: 57 ± 16 yr) and 15 patients with AIS (7 women and 8 men, mean age: 69 ± 8 yr) at two (12 ± 8 days) and three visits (13.3 ± 6.9 h, 4.8 ± 3.2 days, and 93.9 ± 11.5 days from the symptom onset), respectively. All participants were able to complete the RHP protocol without difficulty. Compared with controls, patients with AIS were hypocapnic (all visits, P < 0.0024) and hypertensive ( visit 1, P = 0.011), although BP gradually reduced after the acute phase. RHP demonstrated greater beat-to-beat BP variability (BPV) in controls ( visits 1 and 2, P < 0.001) but not in patients with AIS at any visit. Compared with controls, a reduced autoregulation index (ARI) was demonstrated in patients with AIS, at visit 2 for the baseline recording but not at other visits or during RHP. The area under the receiver-operating curve was 0.53 and 0.54 for baseline and RHP, respectively. The RHP paradigm required minimal patient cooperation and could be considered a feasible alternative for assessing dCA, mainly in conditions leading to increased BPV. The lack of BPV increase in AIS with RHP deserves further investigation.

NEW & NOTEWORTHY This study used rapid head positioning (RHP) to enhance blood pressure (BP) variability (BPV) to improve BP signal-to-noise ratio and reliability of dynamic cerebral autoregulation (dCA). RHP was well accepted by controls and acute ischemic stroke (AIS); the increased BPV induced in controls was not observed in AIS, suggesting BPV at rest was already elevated. RHP did not improve detection of impaired CA in AIS; further work is needed to understand the different responses observed.

Increased blood pressure variability following acute stroke is associated with poor long-term outcomes: a systematic review

BACKGROUND

Blood pressure variability (BPV) in acute ischemic stroke (AIS) may be of prognostic significance. However, methodological heterogeneity of studies may contribute to inconsistent findings, and study findings are therefore not readily comparable. We investigated study methodologies which have assessed the long-term outcomes (≥7 days) of BPV post-AIS.

MATERIALS AND METHODS

The literature search was conducted in OVID Medline, Embase, The Cochrane Library, and Web of Science following a predefined search strategy. Two reviewers independently assessed study eligibility and quality, and source data were extracted.

RESULTS

Of 2044 studies identified, 19 observational studies and one case-control study were included; seven studies were additionally included. Twenty-two studies obtained good risk of bias ratings. Key findings were methodological heterogeneity and significant variability in the reporting of key criteria. Twenty-four studies reported intervals between blood pressure assessments; although 19 studies reported the monitoring device used, only eight studies reported the number of blood pressure measurements taken per visit. The majority measured supine blood pressure (n=13), and eight studies reported whether this was in the hemiparetic or unaffected arm. Sixteen studies defined BPV using SD and seven studies used only a single blood pressure parameter to quantify BPV. Increased BPV was associated with poorer neurological and functional outcomes, and death (n=23); other unfavorable outcomes included irregularly shaped lacunar infarcts, and impaired cognition (n=3).

CONCLUSION

Methodological heterogeneity is frequently observed in studies, primarily because of incomplete study reporting. However, increased BPV is associated with adverse long-term outcomes. There is a need for prospective studies investigating BPV post-AIS to report full methodologies according to standardized criteria.

Blood Pressure Variability in Acute Ischemic Stroke: Influence of Infarct Location in the Insular Cortex

Background: The aim of this study was to elucidate the influence of insular infarction on blood pressure (BP) variability and outcomes according to the region of the insular cortex affected. Methods: A total of 90 patients diagnosed with acute unilateral ischemic stroke were registered. The BP variability was calculated over 24 h after admission (hyperacute) and for 2–3 days after admission (acute). Patients were classified into groups of right and left, and then right anterior, right posterior, left anterior, and left posterior insular infarction. Results: Patients with insular infarction showed a significantly larger infarct volume, higher modified Rankin scale scores, and lower SD and coefficient of variation (CV) of ­systolic BP in the hyperacute phase than shown by patients without insular infarction (p < 0.01, p < 0.01, p = 0.02, and p = 0.03, respectively). The SD and CV of systolic BP in the hyperacute phase showed significant differences among the 3 groups with right insular infarction, with left insular infarction, and without insular infarction (p < 0.05 and p < 0.05, respectively). There was a tendency for the systolic BP variability to be lower in patients with right anterior insular infarction than in patients with infarcts in other areas. Conclusion: The right insular cortex, especially the anterior part, might be a hub for autonomic nervous regulation.

Mid-Term Blood Pressure Variability Is Associated With Clinical Outcome After Ischemic Stroke

BACKGROUND

The aim of this study was to investigate the relation between mid-term blood pressure (BP) variability (BPV) within 7 days of onset and the prognosis in acute stroke patients.

METHODS

Total 873 acute ischemic stroke patients were included in this study. Mid-term BPV was evaluated through the calculations of coefficient of variation (CV) of the systolic BP (SBP) and diastolic BP (DBP) within 7 days of onset. Clinical outcomes were assessed using the recovery situations of neurological function at 3 months, the primary outcome (symptomatic recurrent stroke) and the secondary outcomes (recurrent stroke, all-cause mortality, and the composite of cardiovascular events) within 12 months.

RESULTS

Among 873 patients with ischemic stroke, 83 died, 125 developed recurrent stroke, and 212 developed cardiovascular events during 12 months' follow-up. At 3 months, systolic or diastolic BPV (within 7 days of onset) was associated with the recovery situations of neurological function in three models (all P < 0.05). Both higher CV of SBP and CV of DBP were significantly correlated with the increased risk of recurrent stroke (hazard ratio [HR] = 2.32, 95% confidence interval [CI]: 1.29-4.18, P = 0.005 for CV of SBP; HR = 2.33, 95% CI: 1.29-4.19, P = 0.005 for CV of DBP) and composite cardiovascular events (HR = 2.22, 95% CI: 1.41-3.48, P = 0.001 for CV of SBP; HR = 2.21, 95% CI: 1.41-3.47, P = 0.001 for CV of DBP) during 12 months' follow-up.

CONCLUSIONS

After acute ischemic stroke, high systolic or diastolic BPV within 7 days of onset was associated with the recovery situations of neurological function at 3 months, and recurrent stroke and composite cardiovascular events within 12 months.

CLINICAL TRIAL REGISTRATION

URL: http://www.chictr.org.cn. Unique identifier: ChiCTR-TRC-14004804.

Various meteorological conditions exhibit both immediate and delayed influences on the risk of stroke events: The HEWS-stroke study

We hypothesized that meteorological conditions on the onset day and conditions on the former days may play important roles in the modulation of physical conditions. Associations of meteorological factors and their changes in former days with stroke onset are of interest. We conducted a multicenter retrospective study to evaluate the frequency of stroke events and their interaction with meteorological conditions and their daily changes. Acute stroke patients (n = 3935, 73.5±12.4 years, 1610 females) who were admitted to 7 stroke hospitals in three restricted areas were enrolled in this study. Poisson regression models involving time-lag variables was used to compare daily rates of stroke events with mean thermo-hydrological index (THI), atmospheric pressure, and their daily changes. We divided onset days into quintiles based on the THI, atmospheric pressure, and their daily changes for the last 7 days. The frequencies of ischemic stroke significantly increased when THI varied either cooler or warmer from a previous day (extremely cooler, risk ratio (RR) 1.19, 95% confidence interval (CI) 1.05 to 1.34; extremely warmer, RR 1.16, 95% CI 1.03 to 1.31; r2 = 0.001 for the best regression, p = 0.001). Intracerebral hemorrhage frequencies significantly decreased on high-THI days (extremely high, RR 0.72, 95% CI 0.54 to 0.95; r2 = 0.013 for the best regression, p<0.001) and increased in high atmospheric pressure days (high, RR 1.31, 95% CI 1.04 to 1.65; r2 = 0.009 for the best regression, p<0.001). Additionally, even after adjusting for the THI on the onset day and its changes for the other days, intracerebral hemorrhage increased when THI got extremely cooler in 4 days prior (RR 1.33, 95% CI 1.03 to 1.71, r2 = 0.006 for the best regression, p<0.001). Various meteorological conditions may exhibit influences on stroke onset. And, when temperature cooled, there may be a possibility to show delayed influence on the frequency of intracerebral hemorrhage 4 days later.

Interplay between brain stem angiotensins and monocyte chemoattractant protein-1 as a novel mechanism for pressor response after ischemic stroke

Pressor response after stroke commonly leads to early death or susceptibility to stroke recurrence, and detailed mechanisms are still lacking. We assessed the hypothesis that the renin-angiotensin system contributes to pressor response after stroke by differential modulation of the pro-inflammatory chemokine monocyte chemoattractant protein-1 (MCP-1) in the rostral ventrolateral medulla (RVLM), a key brain stem site that maintains blood pressure. We also investigated the beneficial effects of a novel renin inhibitor, aliskiren, against stroke-elicited pressor response. Experiments were performed in male adult Sprague-Dawley rats. Stroke induced by middle cerebral artery occlusion elicited significant pressor response, accompanied by activation of angiotensin II (Ang II)/type I receptor (AT1R) and AT2R signaling, depression of Ang-(1-7)/MasR and Ang IV/AT4R cascade, alongside augmentation of MCP-1/C-C chemokine receptor 2 (CCR2) signaling and neuroinflammation in the RVLM. Stroke-elicited pressor response was significantly blunted by antagonism of AT1R, AT2R or MCP-1/CCR2 signaling, and eliminated by applying Ang-(1-7) or Ang IV into the RVLM. Furthermore, stroke-activated MCP-1/CCR2 signaling was enhanced by AT1R and AT2R activation, and depressed by Ang-(1-7)/MasR and Ang IV/AT4R cascade. Aliskiren inhibited stroke-elicited pressor response via downregulating MCP-1/CCR2 activity and reduced neuroinflammation in the RVLM; these effects were potentiated by Ang-(1-7) or Ang IV. We conclude that whereas Ang II/AT1R or Ang II/AT2R signaling in the brain stem enhances, Ang-(1-7)/MasR or Ang IV/AT4R antagonizes pressor response after stroke by differential modulations of MCP-1 in the RVLM. Furthermore, combined administration of aliskiren and Ang-(1-7) or Ang IV into the brain stem provides more effective amelioration of stroked-induced pressor response.