Where would I find Why take bp from left arm??

In the right arm, the sub clavian artery is 90 degrees from the aorta, so the pressure is a little less. In the left hand, the sub clavian artery from the aorta has a better angle, around 170 degrees, so it is more trusted as a source of measuring BP and works for most people.

The next time you have your blood pressure checked, don't be surprised if your doctor, nurse, or other health-care provider measures it twice—once in each arm. A significant difference in the pressure recorded in the right and left arms can signal circulatory problems that may lead to stroke, peripheral artery disease, or other cardiovascular problems.

British researchers looked at the results of 20 studies in which blood pressure was measured in both arms. People with an arm-to-arm difference of 15 points or more were twice as likely to have peripheral artery disease—essentially cholesterol-clogged arteries in the arms, legs, or other non-heart parts of the body. The name may sound dismissive, but the disease isn't. Peripheral artery disease affects at least 12 million Americans, more than heart disease and stroke combined. It kills some, maims others, and makes life painful for countless more.

A blood pressure difference of 10 to 15 points or more between arms also boosted the chances of having a stroke or dying from cardiovascular disease.

Different blood pressure readings in the right and left arms that vary by a few points aren't anything to worry about. It's actually quite normal. A difference of more than 10 points, though, could suggest trouble.

In younger people, side-to-side differences in blood pressure can occur when a muscle or something else compresses an artery supplying the arm, or by a structural problem that prevents smooth blood flow through an artery.

In older people, it's usually due to a blockage arising from atherosclerosis, the artery-clogging disease process at the root of most heart attacks, strokes, peripheral artery disease, and other cardiovascular conditions.

A less common cause of blood pressure that is different in each arm is an aortic dissection. This is a tear inside the wall of the aorta, the main pipeline of oxygenated blood from the heart to the body.

At your next doctor's visit, ask to have your blood pressure checked in both arms. If there's a difference greater than 10 point, another test called the ankle-brachial index might be in order to check for peripheral artery disease. It might also be a good time to get serious about taking care of your heart and arteries.

If you take your blood pressure at home, you can do it yourself. There are many good reasons to check your blood pressure at home. The result might be closer to your usual blood pressure than the result in a doctor's office, and you might do a better job of measuring your blood pressure.

That's why the Harvard Heart Letter urges people to check their own. All it takes is a home blood pressure monitor, a few simple instructions, and a few minutes (watch our video on taking your blood pressure).

Here are a few tips to help you start monitoring your blood pressure at home: