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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 research.
It is reasonable to give definition of Cohn (1987): "Bezbolevy ischemia of a myocardium is a passing disturbance of perfusion, a 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 soavt. (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 soavt., 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 soavt. (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.
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 soavt. (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 soavt 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 soavt., 1991).
Interesting researches were executed by Kunkes and soavt. 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 soavt. (1990), Modyn soavt. (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.