Large Difference Between Blood Pressure Numbers

Q.I have a high systolic blood pressure and a low diastolic blood pressure (160/50). What causes this condition and does it require treatment?

A. A systolic pressure reading measures the pressure in the arteries just after the heart contracts; the second number (diastolic pressure) is read as the heart relaxes and refills. Normal blood pressure ranges between about 110/60 and 140/90, and a systolic pressure over 140 is considered high BP, or hypertension.

In most people who develop hypertension, both numbers rise together. But after age 60, the diastolic blood pressure may rise more slowly or even fall. This causes a widening of the pulse pressure (PP) — the difference between the systolic and diastolic readings. Although PP higher than 50 is considered abnormal, some people with PPs greater than 60 have no problems. But in general, the higher the PP, the greater the risk of heart disease.

A leaky aortic valve is another cause of high PP. The faulty valve allows blood to flow backwards into the heart. The result is a lower diastolic BP and a higher systolic BP, because the leaked, extra blood is then re-ejected during the next heartbeat. Clues to this condition include a heart murmur and a wide PP with only a small increase in systolic pressure. Your doctor can confirm this problem with an echocardiogram and recommend specific treatment, which would probably include blood pressure medications (for instance, certain ACE inhibitors or calcium channel-blockers). But if the leakiness is severe, the valve must be surgically replaced.