What is Unstable angina?
This includes patients with more severe or frequent angina superimposed on chronic stable angina, angina at rest or minimal exertion, or angina of new onset (within I month) which is brought about by minimal exertion.
It is a potentially dangerous condition and patients should be admitted to a coronary care unit and begun on antianginal therapy including beta-blockers, aspirin and intravenous nitrates. Intravenous heparin should be started in patients with rest angina of 48 hours duration and in those with chest pain and ischaemic ECG changes on admission. Most patients stabilize with this treatment, although some may require intra-aortic balloon counterpulsation before cardiac catheterization. A monoclonal antibody 7E3 against platelet glycoprotein llb/IIIa, which prevents platelet adhesion and degranulation, is undergoing evaluation in the treatment of unstable angina.
What do you understand by the term 'syndrome X'?
· Syndrome X, or microvascular angina, is the presence of classic angina and ST depression on exercise stress testing and a normal coronary angiogram in the absence of any other demonstrable cardiac abnormalities.
· Reaven's syndrome or 'endocrine' syndrome X is the association of insulin resistance, hypertension, and increased very low density lipoprotein (VLDL) and decreased high density lipoprotein (HDL) cholesterol concentrations in the plasma.
How is angina graded by the Canadian Cardiovascular Society?
There are four functional classes:
· Class I: Angina occurs only with strenuous or rapid or prolonged exertion.
· Class II: There is slight limitation of ordinary activity (e.g. climbing more than one flight of ordinary stairs at a normal pace and in normal conditions).
· Class III: There is marked limitation of ordinary activity (e.g. climbing more than one flight in normal conditions).
· Class IV: Inability to carry out any physical activity without discomfort - anginal syndrome may be present at rest.
What is the mechanism of angina pectoris?
It commonly results from increased myocardial oxygen demand triggered by physical activity, but it can also be caused by transient decreases in oxygen delivery due to coronary vasospasm. Unstable angina is caused by non-occlusive intra-coronary thrombi.
What is the prognosis of patients with angina?
· Fourteen per cent of patients with newly diagnosed angina pectoris progress to unstable angina, myocardial infarction, or death within I year.
· Mortality at coronary artery bypass grafting with normal ventricular function is 1 %.
What is the significance and the mechanism of postprandial angina?
The presence of postprandial angina indicates severe coronary artery disease; one mechanism is 'intramyocardial steal' with blood being distributed from the stenotic territories to the normal territories. It results from the carbohydrate content of the meal; and can be ameliorated by prior treatment with octreotide, which prevents postprandial vasodilatation of the superior mesenteric artery.
What is Prinzmetal's angina?
It is angina occurring at rest, unpredictably, and associated with transient ST seg-ment elevation on the ECG. Coronary vasospasm is the cause, often in the presence of atherosclerosis.
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