La diastolic pressurethe minimum pressure, is the blood pressure value when the heart is in the relaxation phase; in other words, it is the blood pressure between two heartbeats.
Diastolic blood pressure can suffer, permanently, drops (low minimum pressure) or increases (high minimum pressure), which are indicative of something that, in the human body, is no longer functioning perfectly.
Brief review of what blood pressure is
La blood pressure it is the force that the blood exerts against the walls of the blood vessels, as a result of the pumping action carried out by the heart.
Measured in millimeters of mercury (mmHg) and in the resting state, blood pressure is usually defined through the values of systolic pressure e diastolic pressure.
In humans, blood pressure depends on factors, such as:
- Force of contraction of the heart;
- Systolic output (i.e. the amount of blood leaving the heart with each ventricular contraction);
- Heart rate (i.e. the number of heartbeats per minute);
- Peripheral resistances (ie the opposing resistances to the circulation of the blood by the state of constriction of the small arterial vessels);
- Elasticity of the aorta and great arteries (vascular compliance);
- Volemia (i.e. the total volume of blood circulating in the body).
What is diastolic blood pressure?
La diastolic pressure - also called minimum pressure or simply "minima”- is the value of the blood pressure when the heart of an individual relaxes. In other words, it is the value that blood pressure takes when the heart rests between one beat and the next (to understand the mechanism by which the heart works, see the article on cardiac mechanics).
Diastolic blood pressure counteracts the systolic pressure, which is, instead, the value of the arterial pressure at the moment in which the heart of an individual contracts, therefore the pressure value at each heartbeat.
How is blood pressure reported numerically?
Said already of the unit of measurement used, in reporting the blood pressure of a person, doctors compare the systolic pressure with the diastolic pressure. From this it follows that, in the ratio, the upper value is the maximum pressure, while the lower value is the minimum pressure.
Now, if in an individual the systolic pressure is 120 mmHg and the diastolic pressure is 80 mmHg, the pressure ratio (therefore the total arterial pressure) of the subject in question will be written 120/80 mmHg and it will read "120 on 80 mm of mercury ".
Normal diastolic blood pressure
Blood pressure measurement in an individual in excellent health can present
- systolic blood pressure values between 90 and 120 mmHg,
- diastolic blood pressure values between 60 and 80 mmHg.
Hence the so-called normal diastolic pressure it falls within a range of values not lower than 60 mmHg and not higher than 80 mmHg.
Almost always, in association with the systolic pressure, the diastolic pressure can be subject, in a permanent way, to drops or increases that go beyond the normal limits. These alterations generally represent something that, in the human organism, does not work perfectly.
Going into more detail:
- When the diastolic blood pressure is consistently below 60mmHg and the systolic blood pressure is consistently below 90mmHg (so the ratio is <90/60 mmHg), doctors speak of a hypotension o low pressure.
- When the diastolic blood pressure is consistently above 80mmHg but below 90mmHg and when the systolic blood pressure is consistently above 120mmHg but below 140mmHg (so the maximum / minimum ratio is between 120/80 and 139/89 mmHg ), doctors talk about pre-hypertension.
- Finally, when the diastolic pressure is consistently above 90 mmHg and the systolic pressure is consistently above 140 mmHg (so the maximum / minimum ratio is> 140/90 mmHg), doctors speak of hypertension o high pressure.
As readers can note, when you want to evaluate the blood pressure of an individual and any abnormalities, it is necessary to consider, to get a complete picture of the situation, both the maximum pressure and the minimum pressure.
Hypotension or low blood pressure
The state of hypotension can have different origins; in fact, it can be:
- A physiological condition due to genetic factors or the regular practice of physical activity (constitutional hypotension). In these circumstances, the pressure drop is slight in both systolic and diastolic values and lacks any real symptoms.
Generally, constitutional hypotension is not a dangerous condition; indeed, according to some experts, it seems to protect against cardiovascular risk.
- A condition due to a particular disease (pathological hypotension). In such situations, the degree of maximum low pressure and minimum low pressure can be extremely marked and, therefore, cause symptoms and complications.
Pathological hypotension requires ad hoc treatment.
Diseases that can cause a substantial reduction in blood pressure include: Addison's disease, folate or vitamin B12 deficiency anemia, anaphylactic shock, dehydration, myocardial infarction, congestive heart failure, some forms of arrhythmia, bradycardia, valvulopathies, pulmonary embolism, septic shock, acidosis, severe brain trauma and spinal cord injuries.
- A condition resulting from taking certain medications (drug hypotension o iatrogenic hypotension). In these situations, the drop in systolic and diastolic blood pressure is variable, meaning that it can be more or less marked.
Drugs potentially capable of causing hypotension include: drugs with antihypertensive power (diuretics, calcium channel blockers, angiotensin II receptor antagonists, alpha-blockers, beta-blockers, etc.), trinitrine (or nitroglycerin), anesthetics used for spinal anesthesia, narcotics, tricyclic antidepressants, levodopa combined with carbidopa and some erectile dysfunction drugs (e.g. Viagra, Levitra or Cialis) in combination with nitroglyerine.
- A condition due to pregnancy, specifically to the hormonal changes that gestation involves in the woman (gestational hypotension).
Normally, in the first 24 weeks of pregnancy, pregnant women experience an average drop in systolic blood pressure of approximately 5-10 mmHg and an average decrease in diastolic blood pressure greater than 10 mmHg.
To learn more, readers can consult the article: Low Blood Pressure in Pregnancy.
Pre-hypertension is not exactly a pathological state - as is hypertension or intermediate / severe level hypotension - but it is rather a condition to be monitored, as if it were a sort of alarm bell that warns of the presence of something abnormal.
Those suffering from hypertension do not need a drug treatment, but they must change their lifestyle (which is often wrong) and pay attention to:
- Physical activity.
If timely, adopting a healthy lifestyle allows you to control pre-hypertension and bring systolic and diastolic pressure values back to normal.
Hypertension or high blood pressure
Hypertension is a clinically relevant condition which, if not treated appropriately and promptly, can lead to serious complications, sometimes even life-threatening.
In fact, high levels of systolic pressure and diastolic pressure cause arterial blood to flow in such a way as to produce micro-lesions in the arteries in which it circulates, which, precisely for this reason, slowly undergo a process of atherosclerosis (i.e. they undergo a hardening and are the site of atheromas).
Atherosclerosis increases the risk of thromboembolism and affects the blood supply of important organs, such as the brain, heart, kidneys and eyes.