What Does it Mean When the Bottom Number of Your Blood Pressure is Over 100?

When the bottom number of blood pressure is over 100 mm Hg, it may be called diastolic hypertension (DHT).

Diastolic blood pressure means the blood pressure reading during the phase when your heart relaxes (diastole).

The 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 mm Hg. 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 mm Hg means systolic pressure is 130, whereas diastolic blood pressure is 80.
• A systolic blood pressure of less than 120 mm Hg and a diastolic blood pressure of less than 80 mm Hg is generally regarded as normal.
• A blood pressure reading lower than 90/60 mm Hg 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 mm Hg systolic or 10 mm Hg diastolic increase among people who are 40-89 years of age.

When the bottom number of blood pressure (diastole) is over 100 mm Hg, it may be called diastolic hypertension (DHT). The normal range of diastolic pressure should be 60 to 80 mm Hg in adults. Anything above this is considered abnormal (hypertension). However, when blood pressure readings are above 180/120 mm Hg, they are dangerous and require immediate medical attention.

• A high diastolic reading has been linked to a higher risk of diseases involving the large artery called the aorta that carries blood and oxygen from the heart to the abdomen and chest.
• People with an elevated diastolic reading were more prone to developing an abdominal aortic aneurysm, an enlargement of the aorta that may have serious consequences. The problem with such an enlargement is that it can lead to rupture and a high risk of death.
• Few studies and researchers have reported that elevated DBP appears to be associated with cognitive impairment (memory deficit) in people who are 45 years and older. Each 10-point increase over 90 mm Hg was associated with a 7 percent higher risk of problems with cognition, as per studies conducted at the University of Alabama at Birmingham. Although a causal relationship could not be established, it's possible that by preventing or treating high blood pressure, we could potentially prevent cognitive impairment.
• Diastolic pressure of more than 100 mm Hg (DHT) is associated with a significant incidence of strokes.

Diastolic hypertension (DHT) is most commonly associated with the following:

• Increased body mass index (obesity)
• Increased glucose level
• Increased alcohol consumption
• High triglyceride levels
• Family history of hypertension
• Previous cardiovascular events
• Certain factors, such as the male gender, may put you at a slightly higher risk

The decrease in your diastolic blood pressure (DBP) probably represents age-related stiffening of your arteries. Because diastole is a time when the heart receives blood, low diastolic pressure may compromise the blood flow to the heart.

Causes of low diastolic blood pressure are as follows:

• Prolonged bed rest causes a reduction in the tone of the arteries.
• Dehydration due to excess sweating.
• Reduced water intake.
• Loss of water in stools due to diarrhea.
• Loss of water in urine due to medications such as diuretics, antihypertensive medications, medications for Parkinson's disease, narcotics, and antidepressants.
• Alcohol can cause dilation of the blood vessels, which may lead to lower diastolic blood pressure, lower heart rate, malfunctioning of the heart valves, and a heart attack. These are serious disorders that require care and treatment.
• Hormonal deficiencies and other types of endocrine dysfunction, such as hypothyroidism or excessive blood loss during menstruation.
• Allergic reactions due to drugs, food, or insect bites.
• Nutritional deficiency of B vitamins and iron leads to anemia.
• Prolonged standing may lead to blood pooling in the legs.

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 if you have any symptoms of low blood pressure, such as light-headedness, cold and clammy skin, difficulty in breathing, or fainting.

Studies have shown that very low DBP is associated with an increased risk of heart disease. More importantly, a study found that low DBP was associated with an increased likelihood of coronary heart disease events and mortality. Studies explained that if individuals have DBP that is too low, they might not receive enough blood flow to the heart muscle itself, and this could lead to elevations in troponin (cardiac enzyme). Over time, it's not just elevations in troponin but low DBP that cause actual damage to the heart muscle.

Research, however, shows that high systolic readings are the most predictive of a harmful cardiovascular outcome. As a result, they were given more weight in cardiology guidelines and in estimating risk. Having both numbers within a healthy range is good for you and your heart.

Because the risk of cardiovascular events is low in young people, no treatment is required. However, treatment in elderly people should be individualized in such a way that the underlying cardiovascular disease is addressed and the target diastolic blood pressure (DBP) does not fall below 70 mm Hg. Lifestyle measures and weight loss must be initiated.

A study on diastolic hypertension (DHT) reported that calcium channel blockers are frequently used with success.

Other drugs of choice include:

• Angiotensin-converting enzyme inhibitors
• Angiotensin receptor blockers
• Diuretics

Diastolic pressure lower than 60 mmHg is generally regarded as serious. Thus, a diastolic pressure of 64 mm Hg 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 mm Hg along with a systolic blood pressure of more than or equal to 100 mm Hg.