Thyrocardiac heart

Description:

Thyrocardiac heart is a complex of the disturbances of activity of cardiovascular system caused by toxic action of excess of thyroid hormones, which is characterized by development of hyperfunction, hypertrophy, dystrophy, a cardiosclerosis and heart failure.

Reasons of thyrocardiac heart:

Heart hyperfunction (i.e. increase in contractility of a myocardium) is caused by increase in activity of a sympathetic nervous system at which the number of beta adrenoceptors increases in a myocardium and their sensitivity to adrenergic substances increases. Besides, thyroid hormones also directly affect a myocardium. Small doses of thyroid hormones possess anabolic, and big - catabolic effect.

Therefore the strengthened synthesis of protein at the easy course of a thyrotoxicosis leads to a myocardium hypertrophy whereas at a heavy long current synthesis of protein is suppressed, myocardium dystrophy progresses, the miodistrofichesky cardiosclerosis and heart failure develop.

Increase in heart rate, minute volume and change of arterial pressure are characteristic of a thyrotoxicosis. Systolic pressure moderately increases, and diastolic remains normal or lowered owing to what pulse pressure increases. A syndrome of high cordial emission - it is so possible to characterize arterial hypertension at a thyrotoxicosis.

The thyrotoxicosis is followed also by increase in volume of the circulating blood and a packed red cells. Change of serumal level of erythropoetin in response to increase in serumal level of thyroxine is the reason of increase in volume of the circulating blood that leads to increase in mass of erythrocytes.

As a result of increase in minute volume and mass of the circulating blood, on the one hand, and decrease in peripheric resistance, with another, increase the pulse pressure and load of heart in a diastole.

Symptoms of thyrocardiac heart:

The main clinical manifestations of thyrocardiac heart are sinus tachycardia, atrial fibrillation, heart failure and a metabolic form of stenocardia.

Expressiveness of tachycardia against the background of a thyrotoxicosis does not depend neither from emotional, nor on an exercise stress, in particular, it does not decrease during sleep. At a severe disease there is a takhisistolichesky form of a ciliary arrhythmia. At the same time premature ventricular contraction at a thyrotoxicosis meets seldom - its emergence is connected not with a thyrotoxicosis, and with any heart disease postponed before.

In rare instances the sinus bradycardia meets. It can be connected with inborn changes or with exhaustion of function of a sinus node with development of a syndrome of its weakness.

From other disturbances of a rhythm at a thyrotoxicosis on frequency atrial fibrillation is on the second place - it meets in 10-22% of cases. The ischemic heart disease, a hypertension, heart diseases can in itself cause disturbance of a rhythm. In such cases the thyrotoxicosis only accelerates this process. There is a direct dependence of atrial fibrillation on severity and duration of a disease.

Atrial disturbances of a rhythm are more characteristic of a thyrotoxicosis, and ventricular arrhythmias can be revealed only at heavy severity of a disease.

Atherosclerosis of coronary arteries with a thyrotoxicosis occurs at patients less than in the general population that is connected with decrease in level of cholesterol, beta lipoproteids and triglycerides at them in blood. The stenocardia attacks which are noted at patients with a thyrotoxicosis are not a consequence of defeat of coronary arteries, and are caused by excess of hormones of a thyroid gland. And stenocardia in such cases does not disappear during sleep.

The myocardial infarction at a thyrotoxicosis meets seldom. More often the nekoronarogenny necroses of a cardiac muscle connected with direct toxic effect of thyroid hormones on a myocardium come to light.

Dysfunctions of heart can be revealed, including, at a subclinical thyrotoxicosis when for lack of pituitary insufficiency concentration of thyritropic hormone (TTG) is reduced, and concentration of thyroid hormones - is normal. In one of large researches it is revealed that in group of patients the ciliary arrhythmia met with the TTG reduced level in 10 years authentically more often, and mortality was higher.

Treatment of thyrocardiac heart:

Treatment of thyrocardiac heart is directed first of all to decrease in excess products of thyroid hormones, but some changes of cardiovascular system can have irreversible character.