Is a Diastolic Blood Pressure of 64 mmHg too Low?

Medically Reviewed on 5/27/2021
Blood pressure is expressed in mmHg.
Low diastolic pressure in the absence of low systolic pressure is called isolated diastolic hypotension.

Diastolic pressure lower than 60 mmHg is generally regarded as serious. Thus, a diastolic pressure of 64 mmHg is not too low. There may, however, be individual variations. Hence, if you have any symptoms of low blood pressure such as dizziness, confusion, sweating, blurred vision, or unusual thirst, you must seek medical help.

Low diastolic pressure in the absence of low systolic pressure is called isolated diastolic hypotension. It is defined as a diastolic blood pressure of less than 60 mmHg along with a systolic blood pressure of more than or equal to 100 mmHg.

What is diastolic blood pressure?

Diastolic blood pressure means the blood pressure reading during the phase when your heart relaxes (diastole). Force of the blood against the walls of the arteries (the blood vessels carrying blood from the heart to other sites) in the body is called blood pressure. The heart pumps the blood into the arteries as it contracts (systole). This blood pressure reading when the heart is actively contracting to push out blood is called systolic blood pressure. When the heart is relaxing (diastole), some pressure is still exerted on the arterial walls by the blood they contain because of the elastic recoil of the blood vessels. This blood pressure is lower than systolic blood pressure and is called diastolic blood pressure.

Blood pressure is expressed in mmHg. This is because mercury (or Hg) was used in the first accurate pressure gauges and is still being used in medicine today as the standard unit of measurement for pressure. Whenever blood pressure is mentioned, systolic pressure generally precedes diastolic pressure.

  • Thus, a blood pressure of 130/80 mmHg means systolic pressure is 130, whereas diastolic blood pressure is 80.
  • A systolic blood pressure of less than 120 mmHg and diastolic blood pressure of lower than 80 mmHg is generally regarded as normal.
  • A blood pressure reading lower than 90/60 mmHg is generally considered low blood pressure (hypotension).

Both diastolic blood pressure and systolic blood pressure determine the risk of cardiovascular diseases including ischemic heart disease (IHD) such as myocardial infarction or heart attack. According to recent studies, the risk of death from IHD and stroke doubles with every 20 mmHg systolic or 10 mmHg diastolic increase among people who are 40-89 years of age.

Is low diastolic blood pressure dangerous?

Low diastolic blood pressure may cause serious consequences. Diastole is the phase when your heart is relaxing. During this phase, the blood flows through the blood vessels supplying the heart (coronary arteries) to deliver oxygen and nutrients to the heart.

  • Low diastolic pressure may reduce the flow of blood through the coronary arteries thereby increasing the risk of lowered oxygen and nutrient supply to the heart. There is an especially higher risk of reduced oxygen and nutrient delivery to the endocardium or the innermost layers of the heart (endocardial ischemia).
  • Low diastolic blood pressure is also a marker for widened pulse pressure. Pulse pressure is defined as the difference between your systolic blood pressure and diastolic blood pressure. Widened pulse pressure is considered an indicator of increased arterial stiffness and hardening of the arteries caused by fat deposition (atherosclerosis).
  • Furthermore, low blood pressure may increase the risk of falls or accidents because it may cause dizziness or fainting. Thus, it is important to consult a doctor if your blood pressure (diastolic or systolic or both) is low or you have any symptoms of low blood pressure such as light-headedness, cold and clammy skin, difficulty in breathing, or fainting.

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Medically Reviewed on 5/27/2021
References
https://www.medscape.com/viewarticle/480720

https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings