Bezbolevy ischemia of a myocardium

Description:

Bezbolevy ("mute", silentny) myocardium ischemia — a clinical form of coronary heart disease at which passing disturbance of blood supply of a myocardium is not followed by an attack of stenocardia or its equivalents and comes to light only by means of tool methods of a research.
It is reasonable to give definition of Cohn (1987): "Bezbolevy ischemia of a myocardium is a passing disturbance of perfusion, metabolism, function or electric activity of a myocardium which is not followed by an attack of stenocardia or its equivalent".
Bezbolevy ischemia of a myocardium is a widespread state. According to Tabone and соавт. (1993), Vojacek (1993), it is found in 2 — 5% of almost healthy people, in 30% of patients with a postinfarction cardiosclerosis and in 40 — 100% of the patients having stable and unstable stenocardia. Holterovsky ECG monitoring reveals "mute" ischemia of a myocardium at 2 — 4% of healthy men of average years in the European developed countries (Rutishauser and соавт., 1988).
Thus, the provided data indicate that bezbolevy ischemia of a myocardium can be the ischemic heart disease independent form, and can be combined with other forms of coronary heart disease. M. A. Gurevich (1999) emphasizes that about 82% of patients with stable stenocardia have episodes of bezbolevy ischemia of a myocardium (according to daily monitoring of an ECG). A. L. Vertkin and соавт. (1995) specify that only 1/4-1/5 episodes of ischemia of a myocardium are followed by stenocardia whereas 75 — 80% are made by bezbolevy ischemia of a myocardium.

Symptoms of Bezbolevy ischemia of a myocardium:

Types of bezbolevy ischemia of a myocardium:
I type
The most frequent, completely symptomless type, is observed at patients with heavy obstruction of the coronary arteries which do not have in the anamnesis of attacks of stenocardia. These patients have defects of system of perception of pain.

II type
It is observed at the patients who had a reliable myocardial infarction.

III type
It is observed at the patients suffering from other forms of coronary heart disease (stable, unstable, vasospastic stenocardia). Daily an ECG - monitoring demonstrates that within a day at these patients episodes of both painful, and bezbolevy ischemia of a myocardium are observed.

Classification of Conn is not full as does not consider that circumstance that bezbolevy ischemia of a myocardium can be observed also at other forms of coronary heart disease, in particular, at a circulatory unefficiency and disturbances of a cordial rhythm. According to A. L. Vertkin's data and соавт. (1994), congestive heart failure and disturbances of a cordial rhythm more than in 50% of cases are followed by bezbolevy ischemia of a myocardium.
Prevalence of bezbolevy ischemia of a myocardium at patients with various forms of coronary heart disease fluctuates in the following limits (A. L. Vertkin and соавт., 1995; M. A. Gurevich, 1999; S. G. Sudzhayeva and соавт., 1996, etc.):
at stable stenocardia — at 50 — 85% of patients;
at unstable stenocardia — at 74 — 80% of patients;
at the postponed myocardial infarction — at 53 — 79% of patients;
at congestive heart failure — at 60 — 65% of patients;
at disturbance of a cordial rhythm — at 68 — 74% of patients;
after aortocoronary shunting — at 16 — 20% of patients.

It should be noted that the frequency of detection of bezbolevy ischemia of a myocardium depends on sensitivity and specificity of a diagnostic method, and also time of day in which the research was made. It is established, for example, that the majority of episodes of bezbolevy ischemia of a myocardium is registered in early (7:00 — 10:00) morning hours (B. Vezhinskai соавт., 1990; Rocco and соавт., 1987).
It is important to emphasize that episodes of bezbolevy ischemia of a myocardium, as well as stenocardia, can be provoked by an exercise stress, emotional pressure, smoking, cancellation of nitrates even after short-term treatment by them (S.Yu. Martsevich, 1996).

Reasons of Bezbolevy ischemia of a myocardium:

The etiology and pathogeny of bezbolevy ischemia of a myocardium and stenocardia, are generally identical. At the heart of bezbolevy ischemia of a myocardium, as well as stenocardia, atherosclerotic defeat of coronary arteries lies. According to Carvalho and соавт. (1989), at 50% of ischemic heart disease patients with episodes of "mute" ischemia of a myocardium at a coronary angiography considerable atherosclerotic defeat of proximal departments of coronary arteries, and the researches Kumar and соавт is stated. (1989) showed that 100% of patients with "mute" ischemia of a myocardium have a crushing multiple defeat of coronary arteries. Preferential defeat of the main trunk of the left coronary artery, good development of collaterals in the region of blood supply of the affected arteries and big extent of a coronary stenosis are characteristic of bezbolevy ischemia of a myocardium (And P. Savchenko and соавт., 1991).
Interesting researches were executed by Kunkes and соавт. in 1980. Authors compared results of a daily holterovsky ECG - monitoring at 50 patients with bezbolevy ischemia of a myocardium with
given to coronary angiography. It was established that the frequency of bezbolevy infraplacement from the isoline of an interval of ST increased with increase in extent of stenoses and quantities of the struck coronary arteries. Among patients with normal coronary arteries on a koronaroangiogramma the depression of an interval of ST was observed in 2.2% of cases, at defeat of one coronary artery — in 2.9%, at defeat of two coronary arteries — in 8.2%, at defeat of three coronary arteries — in 10.1% of cases.
Summing up the result of discussion of an etiology of bezbolevy ischemia of a myocardium, it is necessary to refer to results of the researches B. A. Sidorenko, A. A. Kosmachev (1989), Bonaduce and соавт. (1990), Modyn соавт. (1998) which demonstrate that the defeat of coronary arteries atherosclerotic process is heavier and stenosis extent is more expressed, the more often at daily holterovsky EKG-monitori-rovaniya are registered episodes of both painful, and bezbolevy ischemia of a myocardium.

Treatment of Bezbolevy ischemia of a myocardium:

In the presence of a clinical picture of an angina of exertion, unstable stenocardia or the isolated bezbolevy ischemia of a myocardium (without clinical manifestations of an ischemic heart disease) treatment is carried out by the standard methods and means (acetylsalicylic acid, nitrates, b-adrenoblockers, blockers of slow calcium channels). Efficiency of treatment is estimated according to daily monitoring of an ECG or exercise tolerance tests.