The effectiveness and use of calcium channel blockers in the management of angina are well established (see Chapter 17); their benefit in postinfarction stages is less certain. Efficacy in angina is largely derived from their hemodynamic effects, which influence the supply and demand components of the ischemic balance (1) by increasing blood flow directly or by increasing collateral blood flow and (2) by decreasing afterload and reducing oxygen demand. All three agents are useful in the management of stable exertional angina, with their vasodila-tory and cardiac effects making beneficial contributions. Given the differences in their relative effects (Table 19.1), the response of the patient can vary with the agent used and the preexisting cardiac status.
All agents are also effective in the control of variant (Prinzmetal's) angina, in which spasm of the coronary arteries is the main factor. Their usefulness in the more complex unstable (preinfarction) angina is less definite, depending on the hemodynamic status and the susceptibility of the patient to infarction.
Was this article helpful?
If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.