Why your heart rate may be low

About low heart rate - or bradycardia - They saywhen the beat rate is less than 60 per minute. The pulse itself is a reflection of the contractions of the heart, which send a shock wave through the vessels. The slower the heart beats, the lower the pulse. And there may be several reasons for this.

1. Exercise stress

The body needs oxygen, and the job of the heart is to circulate blood with this gas throughout the body. When a person engages in sports, the need for oxygen increases, and the load on the heart increases. By adapting, the heart begins to pump blood more efficiently, meaning fewer contractions are required to achieve the desired level of oxygen. This also applies to the state of rest: an already accustomed heart beats less often.

Also from physical activity increases heart volume. Typically, an increase in volume is considered a consequence of increased blood pressure, but in the case of sports it is a “benign” change. Increasing the size and mass of the heart improves its ability to pump blood, which means the heart requires less effort—and less contraction.

And also physical exercise reduce chronic stress levels and anxiety. This, in turn, reduces the activity of the sympathetic nervous system, which is responsible for heart contractions, and the heart rate becomes lower.

2. Age

A decrease in heart rate with age does not always occur and depends from many factors.

• Physiological changes. With age, due to constant pressure on the heart, for example hypertension, the size of the left ventricle increases, and the valves themselves become less elastic. Because of this, the heart contracts more slowly, which leads to a decrease in heart rate.
• Decreased activity of the sympathetic nervous system. This system prepares the body to respond to stress and danger. It accelerates the heart rate, dilates the bronchi to increase the flow of oxygen, increases metabolism, blood pressure and generally prepares the body for physical activity. With age, the activity of this system is decreasing, which can lead to a decrease in heart rate at rest.

3. Effect of drugs

There are several groups of drugs with different mechanisms of action, which reduce pulse. These include:

• beta blockers;
• antiarrhythmic drugs;
• opioid and non-opioid analgesics;
• ACE inhibitors;
• drugs for treatment thyroid gland;
• calcium antagonists.

4. Conduction disorders and other heart diseases

Cardiac conductivity is the ability of cardiomyocytes, that is, heart cells, to generate and transmit electrical impulses that regulate heart contractions. When signal transmission is disrupted Maybe heart rate decreases.

This can happen due to congenital heart abnormalities, and because of acquired ones.

Some diseases also lead to a decrease in heart rate:

• sinus node disease;
• conduction block;
• atherosclerosis;
• acute myocardial infarction;
• acute pericarditis;
• chronic heart failure.

5. Low temperatures

To survive, the body quickly reacts to any changes in the environment, including a decrease in temperature. Exists several mechanisms:

• Vasoconstriction is the narrowing of blood vessels to reduce heat loss. This leads to an increase in pressure in the blood vessels, which signals the sinus node of the heart that the pulse should be slowed down.
• Activation of the sympathetic nervous system - this system initially releases adrenaline, which increases the heart rate, but in the long term leads to vasoconstriction. For example, if a person is in the cold for several hours.
• Slowdown metabolism — the body activates mechanisms aimed at saving energy, including reducing heart activity. This also lowers your heart rate.

6. Injuries

If a part of the body is seriously damaged, the body will try with all its might to neutralize the harmful effect. One of the mechanisms survival - decreased heart rate. This helps slow down bleeding and save energy overall. However, much depends on the location and nature of the injury, and therefore there may be several reasons causing a decrease in heart rate during injury:

• Reduced activity of the sympathetic nervous system - with serious injury, the body can go into a state of shock. The sympathetic nervous system slows down the pulse, preventing the further development of destructive processes in the body.
• Blood loss - during bleeding, the volume of blood circulating throughout the body decreases. Because of this, the heart rate decreases.
• Heart damage is mechanical. In the event of an injury that damages the heart, its conduction and rhythm are disrupted and this can lead to a decrease in heart rate.

7. Lack of oxygen

Hypoxia activates vagal nerve, thereby increasing the production of acetylcholine, which slows the heart rate. This is necessary, because with a lack of oxygen, tissues and organs also lack nutrients. The less cardiac activity, the less oxygen is removed from the body: it remains to circulate in the blood, like other substances needed by the organs.

8. Autoimmune diseases and hypothyroidism

Some autoimmune diseases, e.g. Sjögren's syndrome or systemic lupus erythematosus, can affect the conduction system of the heart, including the sinus node, which regulates the heart rate. In addition, systemic inflammation can affect the heart itself, causing deposition of tissue proteins and subsequent damage to cardiomyocytes. This slows down the conduction of impulses, which leads to a low heart rate.

Autoimmune diseases leading to hypothyroidismdiseases, such as Graves' disease or Hashimoto's disease, interfere with thyroid function. This also causes a decrease in heart rate.

9. Infections

They cause a systemic reaction in the body, that is, activation of several mechanisms to combat them at once. A decrease in heart rate can be a consequence of both the body’s attempt to prevent the further development of a dangerous condition for a person, and the direct effect of infections on the heart. Exists Several reasons for decreased heart rate during infections:

• Inflammation—Some diseases, such as viral and bacterial myocarditis, affect cardiomyocytes. The heart tissue cannot adequately conduct electrical impulses, and the heart rate changes.
• Heat - during fever, the activity of the parasympathetic nervous system increases, which can lead to a decrease in heart rate.
• Toxins in the Bloodstream - Toxic substances circulating in the blood that are released by infections can directly affect the heart and cause changes in rhythm and pulse.
• Dehydration – infections are often accompanied by vomiting and diarrhea, and therefore the volume of blood in the body decreases. This leads to a decrease in heart rate.

10. Toxic substances

Heavy metals, such as lead and mercury, when constantly interacting with them, affect the functioning of the heart, affecting cardiomyocytes and reducing the conduction of electrical impulses.

Some poisons, such as cyanide and insecticides, also can have a toxic effect on the body, including the heart.