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Blood pressure for a normal healthy individual should be 120/80. The upper value is the measure of systolic pressure, while the lower value is the measure for the diastolic pressure. Blood pressure is always expressed as systolic/diastolic pressure. The systolic blood pressure is the pressure that the circulating blood exerts on the arterial wall, when the heart contracts to pump blood into the arteries. On the other hand, diastolic pressure is the pressure with which the circulating blood pushes against the arterial wall, when the heart relaxes after a contraction.

What Causes Diastolic Pressure to Become Low?

Blood pressure, both systolic and diastolic, change over time. The value of diastolic pressure is always lower than the value of systolic blood pressure. Low blood pressure, which is medically referred to as hypotension, occurs when:
  • Diastolic pressure is 60 mm Hg or less
  • Systolic pressure is 90 mm Hg or less
Aging: The diastolic pressure usually rises till midlife, after which it falls. So, for the elderly, a slight drop in diastolic blood pressure is regarded as quite normal. This is because, with age, the aorta stiffens and so, there is less blood available in the arteries when the heart relaxes. Another important cause for low diastolic pressure in the elderly is the use of medications to lower a high systolic blood pressure.

Pregnancy: Both systolic and diastolic blood pressure in pregnant women can fall during the middle of pregnancy, i.e. around 24 weeks of pregnancy. This is however not a cause for concern, and the blood pressure usually returns to its normal level after delivery.

Heart Problems: Heart problems can also lower the diastolic pressure. Slow heart rate, heart failure and pulmonary embolism are some of the heart conditions that can lower diastolic blood pressure. Stiffening of arteries due to arteriosclerosis and diabetes may also cause a drop in the diastolic pressure.

Other contributory factors include:
  • Dehydration
  • Significant loss of blood
  • Severe infection
  • Nutritional deficiency which can result in hypoglycemia (low blood sugar)
  • Anaphylaxis, which is a severe allergic reaction
Symptoms

When the diastolic pressure is too low, the supply of oxygen and nutrients to the body cells reduces. A low diastolic pressure also impedes the removal of waste matter from the cells. This can eventually cause the death of cells. A small drop in diastolic blood pressure may not produce any symptom at times. Sometimes, in the case of a sudden fall in diastolic blood pressure, one can observe symptoms like:
  • Dizziness or lightheadedness
  • Nausea
  • Blurred vision
  • Thirst
  • Cold and pale skin
  • Rapid and shallow breathing
  • Fainting
Treatment

An occasional slight drop in diastolic blood pressure that produces no or only mild symptoms does not require any treatment. However, a consistently low diastolic pressure needs to be properly evaluated by a physician, as it could be a sign of some major health problem. Treatment for such a condition depends on the underlying causes or factors that lower diastolic pressure. Low diastolic blood pressure has been found to be associated with an increased risk for cardiovascular diseases and development of hardened arteries. While drug therapy coupled with lifestyle modifications can certainly prove beneficial for people affected by such conditions, in severe cases medical procedures such as angioplasty or coronary artery bypass grafting may be performed. It would also be in your best interest to quit smoking and avoid excessive consumption of alcohol.

On a concluding note, it is very important to keep track of diastolic blood pressure. If the diastolic blood pressure is persistently low, then the affected individual must seek medical help at the earliest.

Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.