ABSTRACT
Angina pectoris is a distressing symptom resulting from temporary shortage of blood flow to the heart muscle. Patients may describe it as pain, tightness, pressure, aching or choking, mainly in the middle front of the chest. Myocardial oxygen requirements increase when there is an increase in heart rate, myocardial contractility, arterial blood pressure or ventricular volume. Beta-adrenoceptor antagonists are used in the treatment of angina pectoris because they reduce myocardial oxygen demand by decreasing heart rate, myocardial contractility and systemic blood pressure, especially after exercise. The therapeutic effects of relieving chest pain last for about 30 minutes, so there have been various formulations produced to prolong the anti-anginal effects of organic nitrates. Nitrate tolerance occurs when continuous administration results in reduced effectiveness. Beta-blockers are more likely to precipitate heart failure and heart block in patients with angina pectoris compared with those with uncomplicated hypertension.
