Blood pressures in arms don’t have to match

At a routine followup at my doctor’s office, the nurse took my blood pressure on my left arm, and it was 143/73.

This seemed high, so I asked her to check it on my right arm. It was 104/62 on that arm.

She said she had never seen anything like that. Is there a logical reason or explanation for this?

There are several possibilities for having different blood pressures in the arms, all with logical explanations.

The first to come to mind is not the most common in adults, but one we are taught to look for, called coarctation of the aorta.

This is a congenital heart defect where

ANSWER:

there is a narrowing of the aorta (the main blood vessel that comes straight out of the left ventricle).

It can occur in the area between where the blood vessels for the left and right arms originate.

It usually is found in children, but sometimes can be missed until adulthood.

However, since the right side originates closer to the heart than the left, it’s the left side that should have lower blood pressure.

A blockage in the artery going to the arm (there are three: the brachiocephalic, subclavian and brachial arteries; the larger ones, listed first, divide into the smaller ones) can reduce the blood pressure in one arm.

An inflammatory disease of the blood vessel, Takayasu arteritis, can preferentially affect one limb, so it’s important to measure blood pressures in both arms and legs if concerned about this diagnosis.

However, it is prudent to be sure about the measurements before either getting worried or embarking on a search for these conditions.

Blood pressure can change suddenly. I recommend carefully measuring the blood pressure three times in each arm and comparing the average of each arm’s values against the other.

A difference of five to at most 10 points is normal; more than 10 is not normal.

Dr. Keith Roach is a physician and syndicated columnist based in Florida. He regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.

This column appears weekdays.