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Aggressive treatment of hypertension in stroke patients could do more harm than good in the long term, according to a new study from researchers at the University of Georgia.
Sixty percent of stroke patients admitted to U.S. emergency rooms have elevated blood pressure, and many studies say that having high blood pressure at the time of stroke can lead to higher rates of death and major disability.
But lowering blood pressure too much with medications may actually be working against the body’s protective response to maintain blood flow into the affected brain tissues.
“This presents a clinical dilemma,” said study author Changwei Li, an assistant professor of epidemiology and biostatistics at UGA’s College of Public Health.
It may be better to keep blood pressure a little higher than normal, closer to 140/90 mmHg rather than a “good” blood pressure of 120/80 mmHg, but that leaves the question of best practices a little open-ended.
“Currently, hypertension treatment for acute stroke patients is based on physicians’ clinical experience and judgement,” said Li. “There is no guideline on how low the blood pressure should be maintained.”
The key is to find the right balance between maintaining blood flow to the brain and reducing negative short- and long-term effects.
To help identify this optimal blood pressure, Li and his co-authors looked at the relationship between blood pressure during stroke and both short- and long-term health outcomes for over 4,000 Chinese stroke patients participating in the China Antihypertensive Trial in Acute Ischemic Stroke study. One group of stroke patients received extensive treatment for high blood pressure while a control group received no treatment at the time of their stroke.
Li and his collaborators tracked blood pressure changes over time in both the treatment and control groups during the first week of hospital admission and compared patient health at one week, three months, one year and two years following the stroke across patients of different blood pressure trajectories.
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Story Source:University of Georgia. “Optimal blood pressure treatment for stroke patients.” ScienceDaily. ScienceDaily, 10 December 2018. <www.sciencedaily.com/releases/2018/12/181210142059.htm>.
First published on ScienceDaily.com
Some patients with coronary artery disease have inadequate blood flow to the heart muscle during periods of mental/emotional stress. This condition — called “mental stress-induced myocardial ischemia” (MSIMI) — is related to the severity of plaque buildup in the coronary arteries in men but not women, reports a study in Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society. The journal is published in the Lippincott Portfolio by Wolters Kluwer.
Mental stress-induced myocardial ischemia occurs in both men and women, although younger women tend to have more of this phenomenon. While MSIMI is linked to worse cardiovascular outcomes in both sexes, there may be sex differences in the mechanism through which stress can trigger MSIMI, according to new research by Viola Vaccarino, Md, PhD, and colleagues, of Emory University School of Public Health and School of Medicine, Atlanta.
Heart Response to Stress Linked to Coronary Plaque Severity in Men, but Not Women
The researchers examined the sex-specific association between coronary plaque buildup (obstructive coronary disease) assessed from angiograms and MSIMI in 276 participants — 141 men and 135 women — with recent myocardial infarction (heart attack). The study targeted young and middle-aged adults (under age 61). All participants underwent conventional stress testing to evaluate myocardial blood flow in response to a physical or pharmacological challenge (either an exercise stress test or a pharmacological stress test) .
The patients also underwent a mental stress test, which evaluated myocardial blood flow in response to a stressful situation (a public speaking task). Based on a reduction in myocardial blood flow during this stressful challenge, 17 percent of patients were classified as having MSIMI.
Women had a higher rate of MSIMI (20 percent) than men (15 percent). Twenty-seven percent of patients had conventional stress-induced myocardial ischemia (CSIMI). Only 10 percent of patients had both MSIMI and CSIMI.
In both men and women, the presence of CSIMI was associated with greater obstructive coronary disease severity. For each one-unit increase in severity score, the likelihood of CSIMI increased by about 50 percent, after adjustment for other factors.
In contrast, the presence of MSIMI was associated with more severe plaque buildup only in men: for each one-unit increase in severity score, the likelihood of MSIMI nearly doubled. For women, MSIMI was unrelated to obstructive coronary disease severity.
“There is growing evidence that psychosocial stressors may promote the development and progression of cardiovascular disease in susceptible individuals,” according to the authors. However, the relationship between MSIMI and obstructive coronary disease, which means blockages in the major coronary arteries supplying blood to the heart muscle, has been unclear. Women are more likely than men to develop myocardial ischemia without coronary obstruction.
The results support the hypothesis that MSIMI may develop via different mechanisms in women versus men. Consistent with previous findings on sex differences in heart disease, it may be that MSIMI in women mainly reflect abnormalities other than blockage of the coronary arteries, such as malfunction of the smaller coronary blood vessels (microcirculatory dysfunction).
The sex differences may have important implications for understanding sex-specific vascular effects of psychological stress in general and the mechanisms of MSIMI in particular, since most previous studies of this issue have focused on men. Dr. Vaccarino and colleagues conclude, “These results suggest that MSIMI must be driven by alternative mechanisms especially among women, and provide motivation for further research to understand sex-specific mechanisms for the effects of mental stress on myocardial ischemia and long-term outcomes.”
Story Source:Wolters Kluwer Health. “Stress-induced effects on heart blood flow differ for men versus women.” ScienceDaily. ScienceDaily, 26 November 2018. <www.sciencedaily.com/releases/2018/11/181126154101.htm>.
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People who experience migraine with visual aura may have an increased risk of an irregular heartbeat called atrial fibrillation, according to a study published in the November 14, 2018, online issue of Neurology®, the medical journal of the American Academy of Neurology. Migraine with visual aura is when disturbances in vision occur right before head pain begins. Those disturbances may include seeing wavy lines or flashes of light, or having blurry vision or blind spots.
With atrial fibrillation, a form of arrhythmia, the heart’s normal rhythm is out of sync. As a result, blood may pool in the heart, possibly forming clots that may go to the brain, causing a stroke.
“Since atrial fibrillation is a common source of strokes caused by blood clots, and previous research has shown a link between migraine with aura and stroke, we wanted to see if people who have migraine with aura also have a higher rate of atrial fibrillation,” said study author Souvik Sen, MD, MS, MPH, of the University of South Carolina in Columbia. “Atrial fibrillation can be managed through medication, but many people do not realize that they have atrial fibrillation.”
For the study, 11,939 people with an average age of 60 without prior atrial fibrillation or stroke were evaluated for headache. Of those 9,405 did not have headache and 1,516 had migraine. Of those who had migraine, 426 had migraine with visual aura. The participants were followed for up to 20 years.
During the study, 1,623 people without headache, or 17 percent, developed atrial fibrillation while 80 of 440 people with migraine with aura, or 18 percent, developed the condition and 152 of 1,105 people with migraine without aura, or 14 percent.
After adjusting for age, sex, blood pressure, smoking and other factors that could affect risk of atrial fibrillation, people with migraine with aura were found to be 30 percent more likely to develop the condition than people who did not have headaches and 40 percent more likely to develop atrial fibrillation than people with migraine with no aura.
The results translate to an estimated nine out of 1,000 people with migraine with aura having atrial fibrillation compared to seven out of 1,000 people with migraine without aura. Researchers also found that the rate of stroke in the migraine with aura group was four out of 1,000 people annually compared to two out of 1,000 people annually in those with migraine without aura, and three of 1,000 people annually in those with no headache.
“Our research suggests that atrial fibrillation may play a role in stroke in those with migraine with visual aura,” said Sen. “It is important to note that people with migraine with aura may be at a higher risk of atrial fibrillation due to problems with the autonomic nervous system, which helps control the heart and blood vessels. More research is needed to determine if people with migraine with visual aura should be screened for atrial fibrillation.”
A limitation of the study was that the definition of migraine may have left out people who had migraines that lasted less than one year or who had a history of migraine at younger ages. There was also limited information on migraine medications that may influence heart rate.
The study was supported by the National Heart, Lung and Blood Institute and the American Heart Association.
Story Source:American Academy of Neurology. “Migraines that affect vision may increase risk of irregular heartbeat.” ScienceDaily. ScienceDaily, 14 November 2018. <www.sciencedaily.com/releases/2018/11/181114162032.htm>.
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Exposure to environmental noise appears to increase the risk of heart attacks and strokes by fueling the activity of a brain region involved in stress response. This response in turn promotes blood vessel inflammation, according to preliminary research to be presented in Chicago at the American Heart Association’s Scientific Sessions 2018, a premier global exchange of the latest advances in cardiovascular science for researchers and clinicians.
The findings reveal that people with the highest levels of chronic noise exposure — such as highway and airport noise — had an increased risk of suffering cardiovascular events such as heart attacks and strokes, regardless of other risk factors known to increase cardiovascular risk.
The results of the study offer much-needed insight into the biological mechanisms of the well-known, but poorly understood, interplay between cardiovascular disease and chronic noise exposure, researchers said.
“A growing body of research reveals an association between ambient noise and cardiovascular disease, but the physiological mechanisms behind it have remained unclear,” said study author Azar Radfar, M.D., Ph.D., a research fellow at the Massachusetts General Hospital in Boston. “We believe our findings offer an important insight into the biology behind this phenomenon.”
Researchers analyzed the association between noise exposure and major cardiovascular events, such as heart attacks and strokes, among 499 people (average age 56 years), who had simultaneous PET and CT scan imaging of their brains and blood vessels. Diagnostic validation was done in a subset of 281 subjects.
All participants were free of cardiovascular illness and cancer at baseline. Using those images, the scientists assessed the activity of the amygdala — an area of the brain involved in stress regulation and emotional responses, among other functions. To capture cardiovascular risk, the researchers examined the participants’ medical records following the initial imaging studies. Of the 499 participants, 40 experienced a cardiovascular event (e.g., heart attack or stroke) in the five years following the initial testing.
To gauge noise exposure, the researchers used participants’ home addresses and derived noise level estimates from the Department of Transportation’s Aviation and Highway Noise Map.
People with the highest levels of noise exposure had higher levels of amygdalar activity and more inflammation in their arteries. Notably, these people also had a greater than three-fold risk of suffering a heart attack or a stroke and other major cardiovascular events, compared with people who had lower levels of noise exposure. That risk remained elevated even after the researchers accounted for other cardiovascular and environmental risk factors, including air pollution, high cholesterol, smoking and diabetes.
Additional analysis revealed that high levels of amygdalar activity appears to unleash a pathway that fuels cardiac risk by driving blood vessel inflammation, a well-known risk factor for cardiovascular disease.
The researchers caution that more research is needed to determine whether reduction in noise exposure could meaningfully lower cardiovascular risk and reduce the number of cardiovascular events on a population-wide scale.
In the meantime, however, the new study findings should propel clinicians to consider chronic exposure to high levels of ambient noise as an independent risk factor for cardiovascular disease.
“Patients and their physicians should consider chronic noise exposure when assessing cardiovascular risk and may wish to take steps to minimize or mitigate such chronic exposure,” Radfar said.
Story Source:American Heart Association. “Chronic exposure to excess noise may increase risk for heart disease, stroke.” ScienceDaily. ScienceDaily, 5 November 2018. <www.sciencedaily.com/releases/2018/11/181105081749.htm>.
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One of Australia’s biggest health issues could be checked if more people took up yoga or tai chi and reduced their blood pressure, an Australian study has found.
Stroke costs the country $5 billion a year through treatment and loss of productivity, affecting 56,000 Australians in 2017, equivalent to one stroke every nine minutes.
A paper published in Future Neurology by researchers from Monash University, the University of South Australia (UniSA) and the University of Melbourne shows the impact that mindfulness-based interventions (MBIs) such as yoga and tai chi can have on reducing hypertension, fatty acids and blood sugar levels — all risk factors for stroke.
Researchers say both Eastern practices have the potential to mitigate stroke risk as well as help support stroke survivors.
UniSA Senior Lecturer in Human Movement, Dr Maarten Immink, says physical activity plays an important role in preventing recurrent stroke but many stroke survivors may have limited mobility.
“This is where yoga and tai chi are so helpful. They are gentle, movement-based MBIs which help people focus — a state of mind which stroke survivors often lose — and be active at the same time,” Dr Immink says.
The researchers analysed 26 studies published between 1985 and 2017 which examined how yoga and tai chi moderated key stroke risk factors, including blood pressure, cholesterol, diabetes, atrial fibrillation, smoking and alcohol consumption, obesity, anxiety and depression.
UniSA Dean of Health Research, Professor Susan Hillier, says there is increasing evidence that MBIs can be an effective and noninvasive way of reducing hypertension — the biggest stroke risk factor.
“Some evidence suggests that MBIs such as yoga and tai chi regulate blood pressure by teaching people to breathe deeply, balancing and stabilising their autonomic nervous system and lowering their heart rate,” Prof Hillier says.
The stroke specialist says nearly one third of adults around the world suffer from high blood pressure, with 23 million additional strokes projected in the next 12 years.
“Survivors of stroke are at an increased risk of another one — 43 per cent likely within 10 years, 32 per cent within five years and 16 per cent within one year — so it is important we find interventions to help reduce the major risk factors,” she says.
Apart from reducing blood pressure, the research shows that MBIs can help improve diabetics’ health by increasing blood and oxygen supply to the tissues, helping to produce insulin, and boosting anti-oxidants.
Story Source: University of South Australia. “Stroke survivors and those at risk urged to focus on yoga and tai chi.” ScienceDaily. ScienceDaily, 5 November 2018. <www.sciencedaily.com/releases/2018/11/181105105417.htm>.
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About 6 million Australians aged 18 years and over have high blood pressure. Of these, more than two thirds had uncontrolled or unmanaged high blood pressure (not taking medication), representing 4 million adult Australians.
High blood pressure, or hypertension, is suggested to be one of the leading risk factors for heart disease.
The process in which high blood pressure causes heart disease is not completely understood.
But now scientists at the Baker Heart and Diabetes Institute have found that high blood pressure caused by specific signalling from the brain promotes heart disease by altering stem cells with the bone marrow.
The results, published in Haematologica demonstrate how an overactive sympathetic nervous system that causes elevated blood pressure can instruct bone marrow stem cells to produce more white blood cells that clog up blood vessels.
The Baker Institute’s Head of Haematopoiesis and Leukocyte Biology, Associate Professor Andrew Murphy says the findings represent a new era of heart disease research.
“Hypertension is a major, independent risk factor of atherosclerotic cardiovascular disease, but we need more information to determine how it is resulting in heart attacks and strokes,” said Associate Professor Murphy.
Atherosclerotic cardiovascular disease is a build-up of cholesterol plaque in the walls of arteries, causing obstruction of blood flow.
“We now know that significance changes in the immune system contributes significantly to heart disease,” he said. “We aimed to determine how the sympathetic nervous system through the brain directly promotes atherosclerosis in the setting of hypertension.”
“We have discovered that this form of high blood pressure, often associated with stress, causes changes within the bone marrow leading to increased white blood cells circulating though our vessels. This is significant as the general view of hypertension is that it is mainly a disease of the blood vessels, which means other heart damaging events are missed.”
The team is now exploring the specific molecules involved, which may shed light as to why some current therapies are ineffective. They also suggest that managing stress, anxiety and pain are likely to help in controlling this form of hypertension and the effects it has on the body’s bone marrow stem cells.
Story Source: Baker Heart and Diabetes Institute. “Dangerous blood pressure caused by specific signalling in the brain.” ScienceDaily. ScienceDaily, 1 November 2018. <www.sciencedaily.com/releases/2018/11/181101085147.htm>.