Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3720_Библиотеки_им_академика_М_И_Перельмана

The distinction between NSTEMI and STEMI is based on the clinical presentation with chest pain, the presence of positive cardiac biomarkers, and the presence or absence of ST-segment elevations on the electrocardiogram (ECG). Unstable angina is a purely clinical diagnosis in a patient with chest pain, without positive cardiac biomarkers, and without ST-segment elevation on ECG. The patient may have other ECG changes such as ST-segment depressions and/or T-wave changes, which support the diagnosis, but ultimately the diagnosis of unstable angina is a clinical diagnosis based primarily on history and physical examination. While unstable angina is most commonly chest pain at rest, new-onset exertional angina in the previous 2 months and exertional angina of increasing frequency at the same or lower level of exertion are also grouped with unstable angina. These classifications are based on clinical observations in the past that certain patterns of angina were heralds of more serious events such as myocardial infarction and death. For these reasons, what we call unstable angina used to be called preinfarction angina or crescendo angina [3]. With the advent of increasingly sensitive cardiac biomarker tests, we have recognized that most people presenting with chest pain who have high pretest probability for myocardial injury have some degree of positive enzym es, and thus the incidence of NSTEMI has increased while the incidence of unstable angina has decreased [4,5] (Fig. 10 .1). This chapter will focus on unstable angina caused by a thrombus at the site of a ruptured unstable plaque or by erosion of a plaque. The thrombus causes partial or intermittently complete obstruction of flow and ischemia that is pronounced enough to cause symptoms but not prolonged enough to cause myocardial necrosis and abnormal biomarkers.