Review of all causes of heart attack, risk factors

From this article you will learn: what pathologies and risk factors provoke the development of a heart attack. The most common causes of myocardial infarction: a review.

Contents of the article:

Atherosclerosis
Change in blood viscosity
Hypertension
Diabetes mellitus
Vascular spasm
Pathologies not associated with atherosclerosis
Major risk factors

For the development of acute ischemia( oxygen starvation and death of myocardial cells) - or myocardial infarction -coronary arteries feeding the heart, to the critical state( more than 70%).Under such conditions, the volume of blood required for normal excitability, conduction and contractility of cardiomyocytes drops sharply, which leads to their death in a short period of time( approximately 20-30 minutes after constriction).

In hearths whose blood supply has been disturbed, the heart tissue heals with time, cicatrices, but its properties are not restored - it is unable to impulses and contract. This leads to serious, often menacing deviations in the work of the heart muscle( various arrhythmias, blockades).

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The causes of the narrowing of the coronary vessels can be divided into 2 categories:

Pathology.
Factors contributing to the development of threatening stenosis.

Pathologies require compulsory treatment, factors - elimination, because against their background acute myocardial ischemia may recur.

The most common causes and risk factors( in descending order):

1. Pathologies	2. Factors
Atherosclerotic lesion of vascular walls( 90%)	Exchange disorders( hyperlipidemia)
Changes in rheological( physicochemical) blood quality( viscosity, clotting), the number and properties of platelets( strengthened aggregation)	Smoking
Hypertension	Psychoemotional stresses
Diabetes mellitus	Hypodinamia
Sudden vascular spasms( on a background of heightened sensationviability of the vasoconstrictor)	Physical stress
Coronary artery disease not associated with atherosclerosis	Overweight
Chest injuries	Chronic alcoholism

In myocardial infarction, the causes of its occurrence in men and women are the same, the difference is only in that, that against the background of numerous risk factors( mainly smoking, stress and alcoholism), men begin to suffer from atherosclerosis 10-15 years earlier.

Also in women up to a certain point( up to menopause), there is a kind of protective mechanism - a regularly rising level of estrogen. As a result, in the age group from 40 to 60 years in men, myocardial infarction is diagnosed 5 times more often than in women. After 60 statistics are leveled.

If you suspect a heart attack, you need an emergency hospitalization of the patient in cardiac recovery, in the future( during the recovery period and after) the patient is supervised and supervised by a cardiologist.

1. The main cause of acute ischemia - atherosclerosis

Atherosclerotic vascular lesions are the most common cause of cardiac muscle blood supply disorders. In 90-95% formation of atherosclerotic plaques becomes the reason of critical narrowing of coronary arteries( blood supplying heart) and necrosis of cardiomyocytes.

How does arteriosclerosis of blood vessels lead to insufficient blood supply and ischemia? The mechanism is based on a violation of the permeability of the vascular walls, which leads to the formation of plaques from special lipids( cholesterol) and proteins( fibrin, collagen, elastin) of plasma.

In a combination of metabolic disorders( balance of cholesterol) and risk factors that increase the pathological permeability of the vascular walls( tobacco smoking):

cholesterol plaques increase in size to a critical state, disintegrate, and their contents overlap the bloodstream, creating an obstruction to blood flow( embolism at the contents of the atherosclerotic plaque);
, sometimes the brittleness and friability of the vascular walls causes a disruption in the integrity of the inner layer of the vessel( endothelium);
the plaque protein part( fibrinogen) causes platelets and erythrocytes to adhere to the rupture site;
results in a thrombus that can completely or partially block the vascular bed and cause blood flow disorders.

Sometimes( with vasospastic angina), a critical narrowing of the coronary arteries occurs on an area affected by atherosclerosis that has not yet formed a large plaque: stenosis occurs against the background of increased sensitivity of the vascular walls to substances that are released under the influence of nervous or physical stress( thromboxane, angiotensin).

2. Thrombosis

The second most important cause of myocardial infarction and the formation of critical disorders of the blood supply to the heart - thrombosis on the background of changes in blood properties and a pathological increase in the number of platelets. The process is usually combined with atherosclerotic, any organic or post-traumatic damage of the vascular walls.

Mechanism of formation of a blood clot capable of blocking the vessel's channel:

an atherosclerotic plaque or other injury( traumatic injury) of the coronary vessel wall creates conditions for slowing blood flow;
increased viscosity provokes aggregation( gluing, clumping) of erythrocytes into "coin bars" or irregularly shaped lumps;
damage to the vascular wall at the site of an atherosclerotic plaque or any other organic lesion promotes the formation of a primary thrombus( from adherent platelets and fibrin), to which individual or adherent erythrocytes are then "glued".

Blood viscosity may increase with high fluid loss and the use of diuretics( rapid diuresis, excessive sweating, vomiting and diarrhea in intestinal infections, etc.).

In thrombogenesis an important role is played by the change in the number of platelets( an increase in tuberculosis, anemia) or their functional defects( increased aggregation).In violation of the integrity of the vascular wall, excess platelets contribute to the formation of a primary thrombus and increased blood coagulation( clotting, clot formation).

3. Arterial hypertension

Increase in blood pressure provokes the appearance of the reaction of smooth muscle walls - contraction, compaction, spasm. This mechanism develops to protect the vascular bed from damage:

Sharp changes( pressure spike) provoke a strong spasm of large vessels, which causes the violation of blood flow and acute myocardial ischemia.
If the pressure keeps( with hypertension), eventually the vascular spasm becomes permanent, the inner layer of vessels( endothelium) increases in size, increases, decreasing the lumen of the vessels.
Conditions are created for the formation of thrombi and blood supply disorders of the organ.

Arterial hypertension in combination with smoking, hypodynamia, obesity and arteriosclerosis leads to the development of a heart attack in 25% within the next 5 years.

4. Diabetes mellitus

In violation of carbohydrate metabolism:

changes the acid-base balance( pH of the internal environment);
under the influence of a complex of chemical processes reduces the ability of smooth muscle muscles to normal metabolism( metabolism);
inhibits the recovery of cells and provokes increased permeability of the walls;
the structure of the vascular walls varies, they become brittle, brittle, their sensitivity to various vasoconstrictors increases;
this contributes to the development of the inflammatory process, the formation of atherosclerotic lesions or blood clots.

Diabetes mellitus and other disorders of carbohydrate metabolism( glucose tolerance) - the cause of diabetic angiopathy of large and small vessels( vascular pathology, which is accompanied by spasms and muscle wall paralysis).

5. Vascular spasm

The narrowing of large vessels to a critical state( more than 70%) causes the development of myocardial infarction in angina pectoris and in some other cases( taking psychotropic drugs):

under the influence of various factors( for example, smoking), the vascular walls acquire an increased sensitivity to vasoconstrictors, which are released into the blood in the case of nervous, physical and psychicm stress( adrenaline, 33%);
vasospasm can provoke a vegetative nervous system( dysfunction of the sympathetic and parasympathetic departments that are responsible for the automatic reactions of the body - regulate breathing, digestion, tension and relaxation of smooth muscle muscles);
in some cases( 12%) the mechanism of development of critical stenosis is unknown, since it is impossible to establish any connection with any provoking factors( physical activity, psychoemotional stress, etc.).

Most pathological narrowing develops on a segment of the coronary vessel with organic( irreversible) changes( 56%).

6. Coronary vascular lesion not associated with atherosclerosis

Sometimes acute oxygen deficiency and myocardial necrosis develops against a background of diseases and vices not associated with atherosclerosis:

Coronaritis( autoimmune, infectious, rheumatic vascular inflammation).
Congenital defects in the development of coronary arteries( narrowing).
Organic( irreversible) lesion of the vascular wall against a background of metabolic disorders( calcinosis, amyloidosis, mucopolysaccharidosis).

Chest injuries

Mechanical injuries, severe strokes and chest damage can cause the development of myocardial infarction:

when the coronary arteries are deformed, damaged or accompanied by deformities;
with direct exposure to any part of the heart( mechanical damage to blood vessels, disruption of work, blood supply, posttraumatic necrosis of myocardial tissue).

Sometimes, the same consequences are caused by postoperative complications( overlapping of the lumen of blood vessels with thrombus after angioplasty, aortocoronary shunting, installation of pacemakers).

Risk Factors

It is impossible to name risk factors as the direct cause of heart attack in men or women. However, it can be confidently asserted that their influence:

is gradually preparing the "soil" for the development of the disease;
in the presence of any pathological processes of the cardiovascular system, a combination of negative factors stimulates rapid progress from mild to severe stages.

Men are at risk before women( approximately 10-15 years) because of smoking, alcohol addiction and lipid metabolism disorders.

Disorders of metabolism - hyperlipidemia

Approximately a quarter of the world's population has a disturbed balance of blood lipoproteins( a percentage of high and low density cholesterol), which leads to the development of atherosclerosis.

Usually the causes are:

An unbalanced diet, a food rich in animal fats and triglycerides.
Smoking.
Pancreatic and carbohydrate metabolism.
Overweight.
Hormonal reorganization of the body during pregnancy.
Thyroid dysfunction.
Heredity.
Sexual accessory( in men more often than in women).
Hypodinamy.

Some of these factors can not be eliminated( sex, heredity, age), but adjusting the daily diet, reduce excess weight, quit smoking - is vital.

Addiction to nicotine

Smoking is the second most common risk factor, against which a variety of damage to the vascular walls.47% of smokers are guaranteed to develop ischemic disease of different severity, including myocardial infarction.

Nicotine in cigarettes and tobacco:

increases the sensitivity of vessels to vasoconstrictors( adrenaline, aldosterone);
affects the permeability of the walls;
binds active iron in the hemoglobin( the result - with increased hemoglobin, iron deficiency anemia develops);
negatively affects the cellular metabolism;
provokes short-term spasms and relaxation of blood vessels, which eventually leads to a steady narrowing of the vascular bed.

In heavy smokers after extensive myocardial infarction, heart functions are restored worse, and complications develop more often( repeated infarction, malignant arrhythmias).

Psychoemotional stresses

The mechanism of development of vascular spasm in nervous stress is caused by the neurohumoral regulation of the process:

under the influence of stress, the protective mechanisms of the central and autonomic nervous system are included;
they stimulate the release of substances that cause vascular spasm( adrenaline) to increase blood pressure, stimulate heart function and strengthen blood supply to the brain and other organs;
in a state of stress, the body uses reserves and adapts the body( increases its resistance, cellular metabolism, reaction rate, etc.);
with repeated psychoemotional stress reserves of the body are exhausted, stress leads to dysfunction of the nervous system and the regulation of numerous processes, including the reduction and relaxation of blood vessels.

The same happens when excessive physical overload, professional hours of training: the regular release of chemicals( adrenaline), spurring blood pressure, over time can lead to the development of vascular spasm and myocardial ischemia.

Hypodynamia and physical activity

Lack of movement:

Brakes cellular metabolism, provokes metabolic disorders.
Negatively affects the work of any body systems( reduces the contractile function of the heart, reduces muscle tone, vessels and intestines, develops dysfunction of the autonomic nervous system).
Weakened muscle tone leads to the development of vascular insufficiency and violations of blood supply to organs, bone osteoporosis.
On the background of hypodynamia, any physical load can provoke a critical vascular spasm, because due to metabolic disorders, the vascular walls become more sensitive to vasoconstrictors( adrenaline, the release of which accompanies physical stress).

For moderate hypodynamia moderate, but regular exercise is recommended.

Chronic alcoholism

Chronic alcoholism as a disease affects the development of vascular pathologies no less than other risk factors.

Mechanism of damage to the vascular bed with constant use:

the result of oxidation of ethanol( ethyl alcohol) is a toxic chemical compound - acetaldehyde;
acetaldehyde negatively affects the walls of blood vessels of the circulatory system( their permeability increases, cellular metabolism and regeneration of damaged surfaces are delayed);
progresses the general intoxication of the body, atherosclerotic lesion of large and small vessels, excessive sensitivity of the vascular walls to vasoconstrictors;
with time develops dysfunction of the central and autonomic nervous system.

As a result, any dose of alcohol or post-alcohol intoxication may result in a critical vasospasm and the development of acute myocardial ischemia.