Air Pollution Hikes Stroke Risk

by: Rita Jenkins

The type of stroke that results when a blood clot travels to the brain — called an ischemic stroke — is more likely to occur on days when the air contains a larger concentration of particulate matter, according to a study published online in Stroke: Journal of the American Heart Association.

Researchers at Beth Israel Deaconess Medical Center (BIDMC) and the Harvard School of Public Health (HSPH) examined air quality on a total of 37,000 days in nine cities. Risk of hospitalization for ischemic stroke was 1 percent higher on days with relatively high levels of air pollution, compared with low-air pollution days, reports lead author Gregory Wellenius, ScD, postdoctoral fellow in cardiology at BIDMC.

Third Cause of Death in US

“Although these effects sound relatively small,” says Wellenius, “given the large number of people exposed to air pollution and the large number of people at risk for stroke … the actual number of strokes could be significant.”

Stroke is the third leading cause of death in the US, affecting more than 700,000 individuals each year.

A “consistent increased risk” for cardiac health problems associated with exposure to ambient air particles was established in earlier research by Wellenius and coauthors Murray Mittleman, MD, DrPH, of BIDMC’s Cardiovascular Epidemiology Research Unit and Joel Schwartz, PhD, of HSPH.

“Air pollution has been shown to trigger heart attacks and to aggravate the conditions of patients with congestive heart failure,” says Mittleman, who is also an associate professor of medicine at Harvard Medical School.

“These new findings, demonstrating that incidence of clot-based strokes also increase, [are] in keeping with our earlier data showing a relationship between air pollution and heart and lung disorders,” he notes.

The researchers also looked at the incidence of hemorrhagic stroke, which is caused by bleeding in the brain, during the same “high pollution” days, notes Wellenius, but found no association between the two.

Reducing Exposure May Lower Risk

The air pollution in question — particulate matter smaller than 10 micrometers in diameter — includes particles from car and truck exhaust, power plants and refineries. The measurements were provided by the US Environmental Protection Agency from nine US cities: Birmingham, Ala., Chicago, New Haven, Conn., Cleveland, Detroit, Minneapolis, Pittsburgh, Salt Lake City and Seattle.

The authors analyzed hospital admissions among a group of Medicare patients with an average age of 79. Seventy-five percent of the patients were white, and 61 percent were female. Their findings showed that during the course of their study, there were 155,503 hospital admissions for ischemic stroke.

The final analysis demonstrated a 1.03 percent rise in ischemic stroke on the days with the highest pollution measures.

“We don’t know exactly what mechanisms are involved that trigger these cardiac events,” says Wellenius. “However, we do know that particulates in the air promote inflammation, which is a significant risk factor for cardiac events; that exposure to particulates can lead to changes in heart rate and blood pressure; and that pollution can cause changes in coaguable states (related to blood clotting abilities).”

The authors say that future research will focus on finding out which pollutants are most toxic, as well as which patients are at greatest risk for health problems stemming from air pollution.

“Taken together with previous work, these latest results support the idea that reducing exposure to particulate matter may reduce the risk of strokes and heart attacks,” they conclude.

Copyright 2005 Daily News Central

About The Author

Rita Jenkins is a health journalist for Daily News Central, an online publication that delivers breaking news and reliable health information to consumers, healthcare providers and industry professionals: www.dailynewscentral.com.

               

Ischemic and Hemorrhagic Stroke

By Jonathon Hardcastle

Hopefully you never had to endure a situation of someone close to you to suffer from transient ischemic attach (TIA), also known as mini stoke, or from a stroke. In any case, you should be familiar with both kinds of stroke as they both destroy brain tissue and can produce similar long-term effects. But there are important differences in what causes them and in the symptoms that tell you which kind of stroke is happening.

Ischemic Stroke:

According to statistics, 80 percent of strokes belong to the ischemic stroke kind. These mini-strokes occur when blood flow to the brain is blocked by plaque-clogged arteries or by blood clots. This means that blood is not circulating properly inside the brain causing brain cells to die if even for a few minutes no oxygen is transmitted to them via the blood.

- Symptoms: Sudden numbness or weakness, especially on one side of the body; difficulty speaking or understanding speech; trouble seeing in one or both eyes; dizziness and a sudden loss of balance; falling in and out of consciousness; chest pain and shortness of breath. These last three symptoms are less-brain-centered and are more commonly experienced by women.

Hemorrhagic Stroke:

These brain hemorrhages happen when a blood vessel in the brain bursts, spilling blood into the surrounding tissue. There are various causes of these bursts. The most frequent is the rupture of an aneurysm, a weak spot on the wall of an artery that happens to be in your brain-aneurysms can occur elsewhere in the body, too. Experts point out that women are twice as likely as men to have an aneurysm in the brain and are more likely to have multiple aneurysms than men. Two other causes for bleeding in the brain are: hypertension, which can create enough pressure to break an artery wall, and arteriovenous malformation (AVM) in the brain. This is a snarl of defective blood vessels and capillaries whose thin walls are prone to rupture.

- Symptoms: A sudden violent headache, as if cracking a fault like through the brain’s delicate architecture. The patient may also suffer from blurred vision or nausea.

If you ever suspect you might be having a TIA or stroke or believe you are witnessing someone else having one, make sure 911 (or your local emergency unit) be called immediately. Tell the dispatcher that, if possible, you want to be transported to a hospital with a stroke center. Do not attempt to drive to the emergency room yourself. Stroke patients who arrive at the hospital by ambulance are evaluated sooner by an ER physician, get the necessary testing and are admitted to the hospital or intensive-care unit more frequently than those who arrive by taxi or car. Most importantly, bring someone prepared to advocate for you or the patient. Be prepared by being informed and act fast!

Jonathon Hardcastle writes articles on many topics including Health, Education, and Alternative Health

Article Source: http://EzineArticles.com/?expert=Jonathon_Hardcastle