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Which Is More Important: Systolic or Diastolic Blood Pressure?

Systolic vs Diastolic Blood Pressure
Key Takeaways
  • Blood pressure is expressed as systolic (top number) over diastolic (bottom number). Systolic measures pressure during heart contraction, while diastolic reflects pressure during relaxation. Both numbers are important in evaluating cardiovascular health.

  • High blood pressure (hypertension) increases the risk of heart disease, stroke, and kidney issues, while low blood pressure (hypotension) can cause dizziness, weakness, and falls. Monitoring blood pressure is crucial for maintaining health.

  • Both systolic and diastolic pressures need attention. If readings are consistently high, lifestyle changes or medication may be required. Regular blood pressure checks and consultation with a healthcare provider are essential for managing hypertension.

Systole and diastole are two phases of the cardiac cycle that occur when the heart beats. Systole is when the heart contracts and pumps blood from the left ventricle (left lower chamber) into the aorta and rest of the body. Diastole is when the heart relaxes and refills with blood.

Blood pressure readings are expressed in millimeters of mercury (mm Hg) and are represented as systolic pressure over diastolic pressure. For example, a blood pressure reading of 120/80 mm Hg indicates that the systolic blood pressure is 120 mm Hg, while the diastolic blood pressure is 80 mm Hg. It's important to know what these numbers mean, as they can give you valuable insights into your health. Please continue reading to understand the difference between systolic and diastolic blood pressure. 

What Is Systolic Blood Pressure? 

The upper number (first number) is your systolic blood pressure reading. It indicates the pressure exerted by blood flow against the walls of your arteries when your heart contracts during systole. 

What Is Diastolic Blood Pressure?

The lower number (second number) is your diastolic blood pressure, which indicates the pressure in your blood vessels during the rest period between heartbeats (diastole).

 

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Why Your Blood Pressure Matters  

High blood pressure (medical term: hypertension) is one of the leading cardiovascular risk factors worldwide. People with untreated hypertension are at increased risk of heart disease and stroke, which are the leading causes of death in the US. Each year, approximately half a million deaths in the country are attributed to hypertension as the primary or contributing cause. It is estimated that some 116 million Americans (half the total adult population) have high blood pressure. But only 1 in 4 adults with hypertension have their condition under control.

Risks of Abnormal Blood Pressure Levels

Hypertension is often called a “silent killer” because most people who have it don’t have any symptoms. But without treatment, high blood pressure can lead to serious health events like heart attack, stroke, and kidney disease. Blood pressure measurements are the only way to detect hypertension. Your doctor can measure your blood pressure with a blood pressure cuff and stethoscope. You can also measure it at home with a home blood pressure machine.

Understanding your blood pressure numbers is the first step towards controlling high blood pressure with lifestyle changes or medication if needed. That’s why it’s important to learn about systolic and diastolic blood pressure, its role in heart health, and which number in the blood pressure reading is more important.

Which Is More Important — Systolic or Diastolic Blood Pressure?  

Many patients and healthcare providers tend to pay more attention to the systolic blood pressure reading. As noted above, the systolic pressure (the first or top number) represents the pressure in your arteries when your heart contracts. The diastolic pressure (the second or bottom number) is always lower because it reflects the pressure in your blood vessels in the resting phase of the heartbeat cycle. 

The truth is that both the systolic and the diastolic blood pressure numbers are equally important. Experts say that any reading in which the systolic blood pressure is over 130 mm Hg and/or the diastolic reading is 80 mm Hg or higher qualifies as high blood pressure or hypertension and puts you at risk of serious health complications.

What Is A Healthy Blood Pressure?  

A healthy blood pressure is systolic between 90 and 120 mm Hg and diastolic between 60 and 80 mm Hg. Blood pressure above 120/80 mmHg is called high blood pressure (hypertension). Blood pressure below 90/60 mmHg is called low blood pressure (hypotension).

What Are Healthy Ranges for Systolic and Diastolic Blood Pressure?

You can measure your blood pressure with an arm or wrist cuff (home blood pressure machine). Once you have your blood pressure reading, you can use this blood pressure chart by the American Heart Association and American College of Cardiology to find out if your blood pressure is normal, low, or high:

Systolic Blood PressureDiastolic Blood PressureRange
Less than 90 mm HgLess than 60 mm HgHypotension or low blood pressure
Between 90 and 120 mm HgBetween 60 and 80 mm HgNormal range
Between 120 and 129 mm HgLess than 80 mm HgElevated blood pressure
Between 130 and 139 mm HgBetween 80 and 89 mm HgStage 1 hypertension
140 mm Hg or above90 mm Hg or aboveStage 2 hypertension
180 mm Hg or above120 mm Hg or aboveHypertensive crisis

Note: Blood pressure readings of 180/120 mmHg or higher are an emergency and require immediate medical attention. If your numbers are 180/120 mmHg or higher, recheck your blood pressure after 5 minutes. If you continue to have elevated blood pressure, contact your doctor immediately.

What Does a Large Gap Between Systolic and Diastolic Mean?

A large gap between systolic and diastolic blood pressure is called wide pulse pressure. Most people have a pulse pressure (difference between systolic vs diastolic) of 40 to 60. Anything above this is considered a wide pulse pressure. Possible causes of wide pulse pressure include:

It’s important to have the cause of wide pulse pressure diagnosed and treated. Peer-reviewed studies have found that possible health complications of untreated wide pulse pressure include atrial fibrillation (irregular heartbeat), coronary artery disease, and heart attack.

What Can Cause High or Low Blood Pressure?  

Risk factors for high blood pressure include obesity, lack of exercise, high-salt diet, smoking, excessive alcohol use, chronic stress, and certain health conditions.

Medical conditions that can cause high blood pressure include:

  • Essential hypertension (no identifiable cause)

  • Atherosclerosis (plaque buildup in the arteries)

  • Pregnancy

  • Congenital heart defects

  • Vascular problems

  • Adrenal gland tumors

  • Thyroid disorders

  • Kidney disease

  • Obstructive sleep apnea

  • Drug abuse (illegal drugs such as cocaine and amphetamines)

  • Medication side effects (for example, pain medications, hormonal birth control, decongestants, certain antidepressants, ADHD medications)

Causes of low blood pressure include:

What Are The Effects of High and Low Blood Pressure? 

Complications of untreated hypertension (high blood pressure) include:

  • Heart attack

  • Stroke

  • Aneurysm

  • Heart failure

  • Kidney problems

  • Eye disease

  • Metabolic syndrome

  • Memory problems, cognitive dysfunction, dementia

Complications of untreated hypotension (low blood pressure) include:

  • Weakness

  • Dizziness

  • Fainting

  • Falls and injuries

Managing Your Blood Pressure

How Often Should You Check Your Blood Pressure?

The American Heart Association (AHA) and American College of Cardiology recommend that people with high blood pressure monitor their blood pressure at home regularly to help manage the condition. Here are some tips on when to check your blood pressure: 

  • Take your blood pressure twice daily, in the morning and evening. 

  • You don’t have to take your blood pressure immediately after waking up. But you should measure it before taking any medications, eating breakfast, or exercising. 

  • Take 2-3 readings each time to ensure the results are consistent. 

  • Avoid caffeine, alcohol, and smoking for at least half an hour before measuring your blood pressure. 

  • Sit still for 5 minutes before checking your blood pressure. Stay still during the monitoring. Make sure your legs and ankles are not crossed and that your back is supported against a chair. Avoid talking or mental stress.

How To Measure Blood Pressure Accurately  

Here are some tips to measure blood pressure accurately at home: 

  • Take your home blood pressure device to your medical appointments and compare the readings to the ones obtained by your healthcare professional. Also, have your doctor show you how to use the device correctly. 

  • Do not use damaged devices. If you drop the device, have it checked to ensure it is working properly. 

  • Position your arm correctly while checking your blood pressure. Your arm should be resting at heart level on a cushion or table. 

  • Place the blood pressure cuff on the skin and not clothing like shirt sleeves. 

  • Take repeat readings a few minutes after the first one.

  • Write down your blood pressure readings if your device does not record them.

Managing High or Low Blood Pressure  

There are effective treatments available for low and high blood pressure, including lifestyle changes and medications. Your healthcare provider will discuss treatment options with you if you are diagnosed with hypotension or hypertension. 

Learn which medications are most commonly prescribed for cardiovascular disease.

FAQs on Systolic vs Diastolic Blood Pressure  

What Is Better: Low Systolic or Low Diastolic?

As mentioned above, it’s important to keep both blood pressure numbers normal for good heart health. It was previously believed that the risk of cardiovascular disease (in particular strokes) was higher in people with high systolic pressure. The general view was that an elevated diastolic pressure was less problematic. 

However, recent findings from 2019, after an 8-year study involving some 1.3 million adults, have shown that while elevated systolic pressure has a greater effect on the heart, elevated diastolic readings can independently affect a person's risk, regardless of the systolic pressure.

Indeed, some people can have a condition called isolated diastolic hypertension. This is defined as a diastolic blood pressure of more than 80 mm Hg with a normal systolic blood pressure. Observational studies have shown that isolated diastolic hypertension is linked to an increased risk of cardiovascular disease. It is more common in younger individuals, males, and those with high body mass index (people above a healthy weight). Other risk factors include high triglycerides, high blood glucose levels, and increased alcohol consumption.

Is Systolic or Diastolic More Important In The Elderly?

Over the years, studies have shown a greater risk of heart disease and stroke in people with elevated systolic pressures compared to high diastolic pressures. This is especially believed to be true in elderly people (age 50 and above). For this reason, doctors tend to pay more attention to the top number. The difference may be related to the immense force exerted on the large arteries when blood is pumped out from the heart.

Is 140 Over 70 a Good Blood Pressure Reading?

A reading of 140/70 mm Hg is not a good blood pressure reading. A systolic blood pressure of 140 mm Hg or higher is considered stage 2 hypertension even though the diastolic blood pressure reading is normal (less than 80 mm Hg). 

Is 41 Diastolic Too Low?

Yes, a diastolic blood pressure of 41 mm Hg is too low and should be evaluated by a healthcare provider. Doctors consider a diastolic blood pressure between 90 and 60 mm Hg as normal. People with diastolic blood pressure below 60 mm Hg, especially elderly patients, can develop tiredness, dizziness, or falls. This can lead to other potential health risks, such as fractures due to brittle bones

Is 90 Diastolic Too High?

Yes, a diastolic blood pressure reading of 90 mm Hg is too high and qualifies as stage 1 hypertension. Any diastolic reading above 80 mm Hg is considered hypertension (high blood pressure). 

What Is An Alarming Diastolic Number?

An alarming diastolic number is above 120 mm Hg or below 60 mm Hg. If you have a diastolic reading of 120 mm Hg or higher or 60 mm Hg or lower, seek immediate medical attention.

What Does It Mean If Systolic Is High But Diastolic Is Low?

If systolic blood pressure is high but diastolic blood pressure is low, it poses a dilemma. This is because the guideline is to treat high systolic blood pressure, but the low diastolic blood pressure is a contraindication to taking antihypertensive drugs. As a result of this dilemma, many patients with high systolic and low diastolic BP remain untreated. In extreme situations (for example, very high systolic 220 mm Hg and very low diastolic 65 mmHg), most physicians proceed with antihypertensive treatment.

What Does It Mean If Systolic Is High, But Diastolic Is Normal?

If your systolic blood pressure is elevated, but your diastolic blood pressure is normal, it is called isolated systolic hypertension. This is defined as a systolic reading of 130 mmHg or higher and a diastolic reading of less than 80 mmHg. 

Isolated systolic hypertension is a common form of hypertension in elderly individuals (people above the age of 65), but it can occur in younger people too. High systolic blood pressure puts you at risk of heart attack, stroke, and chronic kidney disease. Isolated systolic hypertension is believed to occur due to stiff arteries. It may be associated with obesity, diabetes, hyperthyroidism (overactive thyroid gland), and heart valve abnormalities.

The Main Takeaways

In a nutshell, both the systolic and diastolic pressure readings are important. Elevated blood pressure increases your risk of serious health consequences. That’s why it is important to monitor your blood pressure regularly. If either your systolic pressure or your diastolic pressure or both are high, you should consult a healthcare professional who can provide medical advice, diagnosis, or treatment for hypertension, as appropriate.