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Systolic or Diastolic Blood Pressure

Gabe Mirkin, M.D.

You have two blood pressures: the systolic that measures blood pressure when your heart contracts, and the much lower diastolic reading that measures the pressure when your heart relaxes. When your heart contracts, it pushes a huge amount of blood forward to your arteries. Your arteries are supposed to act like balloons and expand to accept the blood and prevent your blood pressure from rising too high. Having plaques in your arteries stiffens them and prevents them from expanding when your heart contracts, causing your blood pressure to rise higher than normal. The stiffer your arteries, the higher your blood pressure rises. Intense pressure on artery walls can cause damage that provides places for even more plaque to accumulate. It's a vicious circle: high blood pressure continues to cause plaque buildup, which narrows the arteries and increases blood pressure even more.

The Framingham study has shown that the systolic (heart contraction) blood pressure is far more important than the diastolic (relaxation) blood pressure in estimating your risk for a heart attack or stroke. Diastolic blood pressure is a weaker predictor of your susceptibility for a heart attack. Your risk is increased further if you have high blood cholesterol, sugar or insulin levels; an enlarged heart; or if you are overweight. Over time, high blood pressure can cause serious damage to your cardiovascular system, kidneys and other organs.

Anyone with blood pressure over 120/80 should be on my modified DASH Diet. Your doctor will help you decide whether you should also use medication.

WB Kannel.Historic perspectives on the relative contributions of diastolic and systolic blood pressure elevation to cardiovascular risk profile.American Heart Journal, 1999, Vol 138, Iss 3, Part 2, Suppl. S, pp S205-S210.

Checked 5/8/08