HealthMedicine

Left ventricle of the heart: structure, function, pathology

The heart of man and higher mammals consists of four chambers: two atria and two ventricles. Accordingly, the location of the ventricle, like the atrium, is divided into right and left.

The left ventricle is the beginning of a large circle of blood circulation.

Anatomy

The left ventricle and left atrium are transmitted through the left atrioventricular orifice, from the right ventricle of the ventriculus sinister completely isolated by the interventricular septum. From this chamber of the heart there is an aorta, blood on it that is enriched with oxygen, through smaller arteries gets to internal organs.

The left ventricle looks like an inverted cone, and the only one of all the chambers takes part in the formation of the apex of the heart. Due to the larger than the right ventricle, it is believed that the heart is located on the left, although in fact it occupies the center of the thorax.

The walls of the left ventricle have a thickness of ten to fifteen millimeters, which is several times greater than those of the right ventricular wall. This is due to the more developed myocardium on the left side due to higher loads. That is, the higher the volume of work performed, the thicker the heart wall. The left ventricle pushes blood, which participates in a large circle of blood circulation, whereas the right ventricle provides the volume of blood for a small circle. That is why, under normal conditions, the latter is more weakly developed, and its thickness, respectively, is less.

The atrioventricular (orifice) on the left side is closed by the mitral valve, which consists of the posterior and anterior valves. In this case, the anterior one is located in the immediate vicinity of the interventricular septum, and the posterior one is outside of it.

From both valves go chords - tendon threads, fastening the valves to the papillary muscles. Due to these muscles, the valve performs its functions, that is, during the systole there is no return of blood back to the atrium.

Papillary muscles are attached to special myocardial protuberances (fleshy trabeculae), which are located on the inner plane of the ventricle. Such trabeculae are especially developed in the area of the interventricular septum and the apex of the heart, but the number of them in the ventricle on the left is less than on the right.

The length and number of chords of the left ventricle are individual. With age, their length gradually increases, being inversely related to the length of the papillary muscles. Most often the chords that go from one muscle are attached to one leaf. In addition, chords are found that connect the papillary muscles with the trabeculae.

At the exit of the aorta, there is a semilunar valve, through which blood does not return from the aorta into the heart.

The nervous impulse on the left ventricular myocardium comes through a bundle of Guiss (his left leg). It is worth noting that only to the left ventricle the impulse is directed through two branches - the front and the back.

Features of the left ventricle and its function

Regarding other parts of the heart, the left ventricle is located down, behind and to the left. The outer margin is somewhat rounded and is called the pulmonary surface. In the process of life, the volume of this chamber increases from 5.5 cm 3 (for newborns) to 210 cm 3 (by eighteen to twenty five years).

In comparison with the right, the left ventricle has a more pronounced oval-oblong form, much muscled and slightly longer than it.

In the structure of the left ventricle, several departments are distinguished:

  • The anterior (arterial cone) communicates with the aorta through the arterial opening.
  • The posterior (actually the cavity of the ventricle), which communicates with the right atrium.

As mentioned above, due to the more developed myocardium, the thickness of the left ventricular wall is eleven to fourteen millimeters.

The function of the left ventricle is the release of oxygen-enriched blood into the aorta (respectively, into the large circle of circulation), and then through the network of smaller arteries and capillaries nutrition of the organs and tissues of the whole organism occurs.

Physiology

Under normal conditions, the left and right ventricles function synchronously. Their work takes place in two phases: systole and diastole (respectively, contraction and relaxation). Systole, in turn, is divided into two periods:

  1. Voltage: includes asynchronous and isometric contraction;
  2. Exile: includes rapid and slow exile.

Asynchronous voltage is characterized by uneven contraction of myocardial muscle fibers, due to the uneven distribution of excitation. The atrioventricular valve is closed at this time. After the excitation covers all fibers of the myocardium, and the pressure in the ventricles increases, the valve closes and the cavity closes.

After the blood pressure acting on the walls of the ventricle increases to eighty mm Hg. And the difference with the pressure on the aorta is 2 mm Hg. The semilunar valve opens and blood rushes into the aorta. If there is a reverse blood flow from the aorta, the valves of the semilunar valves collapse.

After this, the ventricular myocardium relaxes and through the mitral valve from the atrium the blood enters the ventricle. Then the process repeats.

Left ventricular dysfunction

Isolate systolic and diastolic dysfunction of this chamber of the heart.

With systolic dysfunction, the ability of the ventricle to push blood from the cavity into the aorta is reduced, which is the most common cause of heart failure.

Such dysfunction, as a rule, arises from the decline of contractility, which leads to a decrease in the shock volume.

Diastolic dysfunction of the left ventricle is a decrease in its ability to fill its cavity with blood (i.e., providing diastolic filling). This condition can lead to secondary hypertension (both venous and arterial), which is accompanied by shortness of breath, cough and paroxysmal night dyspnea.

Heart diseases

There are acquired and congenital. The latter are a consequence of developmental disorders in the embryonic period. In the category of congenital malformations included incorrectly formed valves, additional in the left ventricle or with an inappropriate chord length, an unbraced septum between the ventricles, transposition (abnormal arrangement) of the main vessels.

If the child has a defect of the interventricular or interatrial septa, the venous and arterial blood are mixed. Children with similar defects when combined with transposition of blood vessels have a cyanotic skin, which is the only symptom in the beginning.

If transposition is present as an isolated defect, then hypoxia leads to the onset of instant death. In some cases (if a defect is detected before birth), an operation is possible.

Conducting surgical treatment is necessary for other left ventricular defects (eg, aortic valve defects or mitral valve).

Left ventricular hypertrophy

It is characterized by compaction of the ventricular wall.

The reasons for this condition can be:

  • Permanent long-term training (professional sports).
  • Hypodinamy.
  • Smoking of tobacco.
  • Alcoholism.
  • Pharby's disease.
  • Muscular dystrophy.
  • Stress.
  • Pathology of peripheral vessels.
  • Obesity.
  • Atherosclerosis.
  • Diabetes.
  • Ischemia.
  • Hypertension.

Initially, the disease is asymptomatic, and as the process progresses, cardialgia, fainting, dizziness, fatigue occur. Then, heart failure, characterized by shortness of breath (including rest), is added.

Left ventricular failure

Often occurs against the background:

  • Aortic defects.
  • Glomerulonephritis.
  • Hypertonic disease.
  • Myocardial infarction.
  • Syphilitic aortitis.
  • Cardiosclerosis of atherosclerotic.

This pathology is characterized by increasing cyanosis, dyspnea, weakness, pain in the heart, violation of the work of other organs and so on.

Diagnosis of left ventricular pathologies

  • Ultrasound (definition of congenital malformations);
  • ECG;
  • MRI;
  • CT;
  • Chest X-ray;
  • FCG;
  • Echocardiography.

How to treat the left ventricle of the heart

As mentioned above, heart defects most often require surgical treatment.

Hypertrophy of the left ventricle of the heart can be treated with a combination of beta-blockers and "Verapamil". This method allows to reduce the clinical manifestations of pathology. In addition to medicines, it is recommended that the diet and avoid bad habits, weight loss and a decrease in the amount of salt consumed.

The diet should be enriched with sour-milk and dairy products, fruits, seafood and vegetables. In addition, reducing the amount of fats, sweets and flour is mandatory. We recommend moderate exercise.

In addition to conservative therapy, operative treatment aimed at removing the site of hypertrophied myocardium is also used. It should be remembered that this pathology develops for several years.

If it is a case of left ventricular failure, then in this case, use special "heart" drugs: Korglikon, Korazol, Strofantin, Camphora, Kordiamin, as well as oxygen inhalation and bed rest.

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