Is the blood pressure same on both arms?

Is the blood pressure same on both arms?

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Guidelines on hypertension (high blood pressure) generally recommend measurement of blood pressure in both arms in the initial visit. They also suggest that the arm with higher blood pressure recording should be used to record blood pressure in subsequent visits. It is often mentioned that there is a small difference in the blood pressure between the arms and usually it is the right arm blood pressure which is higher.

Blood vessels to both arms arise from the largest blood vessel in the body supplying oxygenated blood known as aorta. The origin of the blood vessel to the right arm is in line with initial part of the aorta. It is presumed that the force of ejection of the left ventricle is conveyed more to the right arm blood vessel for this reason. Left ventricle is the lower muscular chamber of the heart which pumps blood to the whole body.

When there is a significant difference in the blood pressure between the arms, this explanation is not enough. Partial obstruction to one blood vessel is an important reason for lower blood pressure in that arm. Obstruction of blood vessel in the arm is a pointer to disease of blood vessels elsewhere in the body. They are more prone to have heart attack and stroke (brain attack), due to disease of their blood vessels.

Important risk factors of blood vessel disease are high blood pressure and sugar, high blood fat levels, overweight/obesity and smoking. Advancing age, heredity and male gender are also risk factors for diseases of blood vessels. Difference in blood pressure between the arms is more likely in the presence of risk factors.

Another important serious disease which has to be thought of in a person with pain in the chest or upper back is aortic dissection. Aortic dissection is break in the inner lining of the aorta. Blood seeps into the wall of the aorta and spreads along the wall of the aorta. As this progresses, it can obstruct the openings of the major branches. In those coming to emergency department with severe chest pain or upper back pain, if there is a large difference in the blood pressure between the arms, this serious condition has to be thought of.

Among the blood vessel diseases, an important variety is obstruction due to inflammation of the aorta, known as aortoarteritis. The disease is also known as Takayasu arteritis, after the person who described it. It is also known as pulseless disease as arm pulses may be absent due to obstruction of the blood vessels. It is a progressive disease with more and more blood vessels getting affected as time passes.