Angina pectoris25

An attack of angina pectoris26 occurs when myocardial demand for oxygen exceeds supply from the coronary circulation.

The principal forms relevant to choice of drug therapy are angina of exercise (commonest) and its worsening form, unstable (preinfarction or crescendo) angina (see below), which occurs at rest. Variant (Prinzmetal) angina (very uncommon) results from spasm of a large coronary artery.

Antiangina drugs act as follows:

• Organic nitrates reduce preload and afterload and dilate the main coronary arteries (rather than the arterioles).

• p-adrenoceptor blocking drugs reduce myocardial contractility and slow the heart rate. They may increase coronary artery spasm in variant angina

• Calcium-channel blocking drugs reduce cardiac contractility, dilate the coronary arteries (where

25 Angina pectoris: angina, a strangling; pectoris, of the chest.

26 For a personal account by a physician of his experiences of angina pectoris, coronary bypass surgery, ventricular fibrillation and recovery, see Swyer G I M 1986 British Medical Journal 292: 337. Compelling and essential reading.

there is evidence of spasm) and reduce afterload (dilate peripheral arterioles).

These classes of drug complement each other and can be used together. The combined nitrate and potassium-channel activator, nicorandil, is an alternative when any of the other drugs is contraindicated.

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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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