The study of the physical parameters of the myocardium is very important in the diagnosis and further treatment of patients suffering from diseases of the cardiovascular system. Heart muscle hypertrophy is a dangerous syndrome that can lead to dangerous complications and death. Therefore, this problem is relevant at the present time and requires careful consideration.
Characteristics of the myocardium and methods for their calculation
The myocardium is the muscle layer of the heart, which consists of mononuclear cells with a special transverse arrangement. This provides the muscle with extreme strength and the ability to evenly distribute work throughout the heart. The interposition of cells by the type of intercalated discs determines the extraordinary properties of the myocardium. These include excitability, contractility, conduction, relaxation, and automatism.
It is possible to assess whether the heart is healthy with the help of additional instrumental examinations. Normal indicators based on the results of echocardiography of the ventricular myocardium (one of the key methods for diagnosing the pathology of blood ejection) are as follows:
- left ventricle (LV): myocardial mass - 135-182 g, 95-141 g; mass index (LVMI) - 71-94 g / m2, 71-84 g / m2 in men and women, respectively;
- right ventricle (RV): wall thickness - 3 mm; size index - 0.75-1.25 cm / m2; the value of diastole at rest is 0.8-2.0 cm.
The left ventricle takes on a greater functional load than any other part of the heart, therefore, it is more likely to be subject to pathological changes. Therefore, we will consider its parameters in more detail.
The calculation of the mass of the left ventricular myocardium is obtained by performing various calculations. The calculator processes numbers using special formulas. At the present stage, 2 forms of calculation are recognized as the most sensitive ones, which are recommended by the American Society of Echocardiography (ASE) and Penn Convention (PC)... The difference between them is only in the inclusion of the thickness of the inner layer of the heart when using the first formula.
So, the formula for determining the mass of the myocardium is as follows:
0.8 x (1.04 x (MLP + KDR + ZSLZh) x 3 - KDR x 3) + 0.6, where
- MVP - this is the interventricular septum in diastole;
- CRA - this is the end-diastolic size of the left ventricle;
- ZSLZH - This is the posterior wall of the left ventricle during the relaxation period.
The norm of the mass of the left ventricular myocardium depends on gender. For men, this value is about 135-182 g. For women, these figures are lower and range from 95 to 141 g.
It has been scientifically proven that the weight of the myocardium is closely dependent on body size (in particular, on the mass-growth rate). In this regard, a special index was introduced, which takes into account all the individual characteristics of the patient, even his age. There are two formulas for calculating it:
- IM = M / H2.7, where M is the mass of the LV myocardium in g; H - height in m. Used in pediatrics;
- IM = M / S, where M is the mass of the heart muscle in g; S - body surface area, m2... Used for adults.
The normal mass index of the left ventricular myocardium is 111 g / m2 and 135 g / m2 in men and women, respectively.
A special table is used, in which the calculation of these parameters is entered, on the basis of which a conclusion is formed.
What are the physical parameters of the heart muscle for and what deviations can they indicate? The growth of the above indicators indicates a probable risk or already acquired myocardial hypertrophy. With pathological proliferation of the myocardium, the thickness of the wall itself, more often of the left ventricle, increases, with the possible involvement of even the interventricular septum in the process. The norm for the thickness of the left ventricular myocardium is no more than 1.0-1.2 cm.
Nevertheless, it is not worthwhile to independently interpret the results of echocardiography. Even after examining all the indicators in detail, you can only compare them with the variants of the norm, and the final diagnosis will be made by a specialist - a cardiologist, evaluating all the parameters in aggregate.
The variant of a normal increase in the heart muscle is possible in athletes, when, under intense loads, the myocardium must adapt in order to deliver oxygen to all organs and tissues. This habituation process is reproduced in the form of muscle tissue growth - the so-called sports heart syndrome. However, this "norm" is relative, since over time, left ventricular hypertrophy can become pathological and lead to the development of heart failure.
Therefore, regardless of the reason, the person who, as a result of the examination, revealed a hypertrophied myocardium, must necessarily be under the supervision of a doctor.
Why determine the myocardial mass index
LVH is a rather lengthy process of the compensatory reaction of the heart muscle. Myocardial hypertrophy is not a disease, but a syndrome that can lead to serious complications. The development of this condition can be due to both hereditary predisposition and lifestyle.
Genetic factors include gender (the risk is higher in the male population) and angiotensin-converting enzyme gene polymorphism. This, in turn, causes further pathophysiological changes in LVH. They are in direct proportion to the amount of angiotensin in the body. Also, uncontrolled arterial hypertension can be attributed to risk factors.
According to the classification of the American scientist Robbins, the formation of health in 51-52% depends on the way of life. The negative aspects include alcohol abuse, smoking, an increase in body mass index (BMI) above 30 and, oddly enough, professional sports.
Unfortunately, the child can also be susceptible to myocardial hypertrophy. This is possible if there is a history of congenital heart defects (coarctation and stenosis of the aorta, patent ductus arteriosus, IVS defect, stenosis of the pulmonary artery, etc.), endocrine diseases, and various kidney pathologies.
From an anatomical point of view, concentric hypertrophy of the left ventricle is distinguished, which is characterized precisely by the thickening of its walls, and eccentric, in which the wall thickness is relatively preserved, but its mass and cavity dimensions increase.
Diagnosing hypertrophy is easy. It can be suspected in routine electrocardiography, where it manifests itself as a deviation of the axis to the hypertrophied area, impulse conduction disturbance, ischemic changes, etc. But only a specialist can correctly interpret these data. An ultrasound of the heart will show a digital characteristic that will help determine the severity of the pathology. With an increase in wall thickness from 11 to 21 mm, one speaks of moderate hypertrophy. 21-25 mm is already an average severity. More than 25 mm indicates pronounced LVH.
The danger of this condition is that even when the mass of the left ventricular myocardium is increased, there are still no clinical manifestations. This can continue until the exhaustion of the compensatory capabilities of the heart. Nonspecific symptoms include weakness, dizziness, and fainting. In the future, angina attacks often occur, as there is a mismatch between the delivery of oxygen to the enlarged heart and its needs. Edema appears in the late afternoon, shortness of breath, arrhythmias.
All this indicates the beginning of the stage of decompensation and requires compulsory treatment.
Left ventricular hypertrophy is fortunately a reversible condition. Treatment for this syndrome should begin with lifestyle modifications.It is necessary to give up bad habits, optimize the exercise regimen, and bring your weight back to normal. A diet with limited salt and animal fats is recommended. The daily diet should be enriched with vegetables and fruits, fermented milk products and herbs.
The actual treatment of LVH occurs in two stages. At the beginning, it is necessary to prevent the deterioration of the condition, and then try to remodel the heart muscle, up to the normalization of the indicators of myocardial mass, wall thickness and cavity dimensions.
You cannot do without the use of medicines. In this situation, the prescription of the following drugs is justified:
- beta-blockers - reduce myocardial oxygen demand and reduce the negative effects of the sympathoadrenal system;
- ACE inhibitors - recommended for hypertension, reduce the progression of hypertrophy;
- calcium channel blockers - reduce the contractile function of the heart, which also improves subjective manifestations;
- antiarrhythmic drugs - this drug recommendation is relevant in the presence of complications;
- the criteria for the effectiveness of therapy are an improvement in the quality and an increase in life expectancy, the absence of further development of heart failure.
The study of the physical parameters of the myocardium is very important in the diagnosis and further treatment of patients suffering from diseases of the cardiovascular system. Myocardial hypertrophy is a dangerous syndrome that can lead to complications and death, even if you are an athlete. To this end, one should carefully monitor blood pressure indicators, twice a year, even in the absence of complaints, consult a cardiologist, undergo a preventive examination. Hypertrophy detected in time is always amenable to correction, which reduces the threat of complications and contributes to a favorable prognosis for recovery.
