Systolic and diastolic pressures
Last reviewed: 07.06.2024
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Systolic and diastolic pressure are two key parameters used to measure blood pressure in the body.
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Systolic pressure (upper blood pressure): Systolic pressure measures the pressure in the arteries at the moment of heart contraction, when blood is ejected from the left ventricle into the aorta and travels through the arteries in the body. It is the highest pressure in the arteries during the cardiac cycle. Typically, systolic pressure is measured in millimeters of mercury (mmHg) and is written as the first number in blood pressure, such as 120 mmHg.
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Diastolic pressure (lower blood pressure): Diastolic pressure measures the pressure in the arteries while the heart is resting and relaxing between heartbeats. It is the lowest pressure in the arteries during the heart cycle. Diastolic pressure is also measured in millimeters of mercury and is recorded as the second number in blood pressure, such as 80 mmHg.
Typically, blood pressure is expressed as the ratio of systolic pressure to diastolic pressure, such as 120/80 mm Hg. These numbers provide information about how the cardiovascular system is functioning. High blood pressure values can indicate hypertension (high blood pressure), which can be a risk factor for cardiovascular disease, while low values can be a sign of hypotension (low blood pressure). Monitoring blood pressure is important for maintaining heart and vascular health.
Normal blood pressure values according to WHO
Normal blood pressure values may vary slightly with age, but it should be noted that "normal" BP values may have different ranges in different medical sources and recommendations. Common target ranges for healthy adults may be as follows:
For adults (age 18 and older):
- Systolic blood pressure: Usually less than 120 mmHg.
- Diastolic pressure: Usually less than 80 mmHg.
However, it is important to realize that optimal blood pressure values can vary slightly from person to person depending on their overall health, heredity, and other factors. It is also important to note that BP readings can fluctuate throughout the day and can be influenced by various factors such as physical activity, stress, diet and others.
Blood pressure levels are usually monitored by a physician or other qualified health care professional.
Symptoms of high blood pressure
High blood pressure (hypertension) is often asymptomatic, especially in its early stages. This means that many people can have high blood pressure and not know it until they have a medical checkup. However, in some cases, high blood pressure can manifest itself with the following signs and symptoms:
- Headache: Frequent, throbbing headache, especially in the back of the head. Hypertension may cause migraines or tension headaches.
- Shortness of breath: Shortness of breath or a feeling of shortness of breath may occur with physical activity or at rest.
- Eye hemorrhage: Uncontrolled bleeding from theblood vessels of the eye fundus can be a sign of high blood pressure.
- Heart palpitations: A fast or irregular heartbeat (arrhythmia) may be associated with high blood pressure.
- Dizziness: Feeling like the room is spinning can sometimes be associated with hypertension.
- Tinnitus: No ise or whistling in the ears (tinnitus) can be caused by high blood pressure.
- Visionloss: High blood pressure can affect vision, causing changes in the visual field or even vision loss in case of complications such as hypertensive retinopathy.
- Tingling in the arms and legs: High blood pressure can cause a decrease in blood supply to the extremities and lead to a tingling or numbness sensation.
- Feelingtired: Hypertension can cause feelings of fatigue and general weakness.
- Increased need to urinate: Some people with high blood pressure may experience frequent urination.
Symptoms of low blood pressure
Low blood pressure, also known as hypotension, can manifest itself with a variety of symptoms. Symptoms of low blood pressure can vary depending on your individual body, the degree of low blood pressure, and the causes of hypotension. Here are some common symptoms of low blood pressure:
- Dizziness: This is one of the most common symptoms of low blood pressure. Dizziness can be a feeling of unsteadiness or loss of balance.
- Feeling weak: Patients with low blood pressure may feel weak and tired, sometimes even to the point of having difficulty getting out of bed or performing normal daily tasks.
- Drowsiness: Hypotension can cause drowsiness and fatigue during the day.
- Loss of consciousness (syncope): In some cases, low blood pressure can lead to loss of consciousness. This can happen, for example, if you change your body position suddenly, such as getting up from sitting or lying down (orthostatic hypotension).
- Feeling heavy in the head: Patients may feel pressure or heaviness in the head area.
- Skin pallor: The skin may become pale due to insufficient blood circulation.
- Cold extremities: Hands and feet may be cold to the touch due to decreased blood flow.
- Visual disturbances: Low pressure can cause blurred vision, "flies" in front of the eyes, or even a brief vision of blackness.
- Palpitations: Some people with hypotension may experience palpitations (tachycardia) in an attempt to compensate for the lowered blood pressure.
- Nausea and vomiting: Low blood pressure may cause nausea and vomiting in some patients.
Symptoms of low blood pressure can be temporary and intermittent, especially when changing body position or if you are not adequately hydrated. If you experience frequent symptoms of hypotension or have reason to believe that you have low blood pressure, it is important to consult a physician to diagnose and manage the condition. Your doctor can perform an evaluation and, if necessary, prescribe treatment or recommendations for lifestyle changes.
Causes of blood pressure deviation from the norm
High systolic and low diastolic blood pressure can be caused by a variety of factors and medical conditions. This condition is sometimes called "isolated systolic hypertension" and means that the top number (systolic pressure) is elevated while the bottom number (diastolic pressure) remains normal or low. Here are some of the possible causes of high systolic and low diastolic blood pressure:
- Aging: Older people often have an increase in systolic blood pressure, while diastolic blood pressure may decrease.
- Elevated cardiac output: A high systolic reading may be associated with increased blood output by the heart, such as increased cardiac activity.
- Aortic contractility: Increased systolic pressure may be associated with changes in aortic contractility, which increases the force of blood ejection.
- Highpulse pressure: This is the difference between systolic and diastolic blood pressure. If pulse pressure is high, it can lead to high systolic pressure and low diastolic pressure.
- Arterial stiffness: Increased arterial wall stiffness can increase systolic pressure and decrease diastolic pressure.
- Pathologic conditions: Certain medical conditions such as arteriosclerosis, vascular disease, endocrine disorders (e.g., hyperthyroidism), and other diseases can cause changes in blood pressure.
- Medications: Some medications can affect blood pressure and cause changes in systolic and diastolic blood pressure.
It is important to note that high systolic blood pressure, especially with low diastolic blood pressure, may be associated with an increased risk of cardiovascular complications, so it is important to seek medical attention for diagnosis and treatment. Blood pressure levels should be considered in the context of other risk factors and overall health.
High diastolic pressure with normal systolic pressure can also be a medical condition that requires attention and diagnosis. This condition is sometimes called "isolated diastolic hypertension" and means that the lower number (diastolic pressure) is elevated while the upper number (systolic pressure) remains normal.
Causes of high diastolic pressure with normal systolic pressure may include:
- Arteriosclerosis: Thickening and stiffness of arterial walls that can lead to increased diastolic pressure.
- Aging: As we age, blood vessels can lose their elasticity and this can affect diastolic blood pressure.
- Pathologic conditions: Certain diseases such as chronic kidney disease, endocrine disorders (e.g., hypothyroidism), and other medical conditions can affect diastolic blood pressure.
- Medications: Some medications, including steroids and some blood pressure medications, can increase diastolic blood pressure.
High diastolic blood pressure may also be associated with an increased risk of cardiovascular complications, including stroke and heart disease. Therefore, it is important to consult with a physician for diagnosis and to develop a treatment plan, which may include lifestyle changes, diet, exercise, and medication if necessary. Controlling blood pressure and following your doctor's recommendations are important for maintaining cardiovascular health.
High diastolic pressure with low systolic pressure is unusual and can be caused by a variety of medical conditions or factors. This condition is not as common as high systolic pressure with low diastolic pressure and requires a more detailed medical evaluation to determine the cause. Some of the possible causes include:
- Hypotension: Hypotension, or low blood pressure, can lead to low systolic blood pressure. High diastolic pressure with low systolic pressure may be the result of an uncontrolled decrease in diastolic pressure.
- Acute heart failure: An uncontrolled drop in systolic blood pressure may be a sign of acute heart failure, when the heart cannot effectively contract and squeeze blood out.
- Heart valve disease: Heart valve problems can alter blood pressure characteristics, including systolic and diastolic pressures.
- Complications of medications: Some medications, such as diuretics, can affect blood pressure in different ways and lead to these abnormal readings.
- Other diseases: Rare diseases such as aortic dissection or arteriovenous malformation may also cause unusual pressure values.
You should see your doctor immediately to determine the exact cause and develop a treatment plan. Your doctor will perform further evaluation, including a physical exam, tests, and possibly instrumental tests, to determine what is causing the unusual blood pressure values and how to treat the condition.
Low diastolic blood pressure (lower blood pressure value) with normal systolic blood pressure (upper blood pressure value) can have different causes and may be called isolated diastolic hypotension. This condition can result from a variety of factors and can be temporary or chronic. It is important to see a doctor to evaluate and determine the cause of low diastolic blood pressure. Below are some possible causes:
- Physical activity: After physical activity, diastolic blood pressure may temporarily decrease in some people while systolic blood pressure remains normal.
- Decreased blood volume: If the circulating blood volume decreases, for example due to dehydration or blood loss, this can lead to a decrease in diastolic pressure.
- Stress and anxiety: Emotional stress and anxiety can cause a temporary decrease in diastolic blood pressure.
- Medications: Some medications, such as diuretics or blood pressure medications, can lower both systolic and diastolic blood pressure.
- The "white coat" effect: Some people's blood pressure rises in the clinic or when they see a doctor (white coat syndrome), and this can lower diastolic blood pressure in a normal environment.
- Medical Conditions: Low diastolic blood pressure can be the result of certain medical conditions such as heart failure or shock.
If you find low diastolic blood pressure and are worried about it, it is important to consult your doctor. Your doctor will review your medical history, perform a physical exam and, if necessary, perform additional tests to determine the cause and decide if treatment or lifestyle adjustments are needed.
Causes of low and high pulse pressure
A large difference between systolic and diastolic pressure, also known as "pulse pressure", is a normal physiological parameter. Pulse pressure is the difference between the maximum (systolic) and minimum (diastolic) pressure in the arteries and is usually between 30 and 40 mmHg. For example, if your systolic pressure is 120 mmHg and your diastolic pressure is 80 mmHg, your pulse pressure would be 40 mmHg (120 - 80).
Pulse pressure plays an important role in circulatory regulation and has several important physiologic functions:
- An indicator of cardiac function: An increase in pulse pressure may indicate a stronger heart contraction and a better ability to pump blood.
- Dependence on circulatory volume: Pulse pressure affects perfusion (blood flow) in organs and tissues. A large difference between systolic and diastolic pressures can mean that the organs are getting enough oxygen and nutrients.
- Regulation of vascular tone: Pulse pressure helps regulate vascular tone and pressure in the arteries, which is important for adequate blood flow.
However, it is extremely important that your pulse pressure is within normal limits. Too high a pulse pressure (a large difference between systolic and diastolic, more than 40 mm Hg) may be associated with an increased risk of cardiovascular disease, including heart disease and stroke, and arterial stiffness. On the other hand, too low a pulse pressure (less than 30 mm of mercury column) may also indicate circulatory problems such as heart failure, shock, decreased circulating blood volume, arrhythmias, and other factors