Calcium channel blocker

Calcium channel blockers relieve coronary spasm, increase myocardial oxygen supply, and reduce myocardial oxygen consumption, thus alleviating the symptoms of variant angina. Although this product can prevent the increase of coronary artery tension, it is not as good as the effect of nitroglycerin on the basic tension. The effect of calcium antagonists on variant angina may be comparable to nitrate and stronger than beta blockers. Nifedipine, diltiazem and verapamil have comparable effects on variant angina. Calcium channel blockers do not appear to reduce the morbidity and mortality of high-risk patients. For classic angina, calcium channel blockers reduce the number of occurrences, reduce the need for nitrates, and improve exercise performance. These effects are mainly due to the reduction of myocardial oxygen demand. To compare the relative efficacy of various calcium antagonists in patients with classic angina, the results have not been consistent. Calcium antagonists are indicated in patients with exertional angina, such as nitrate ineffective or difficult to tolerate, or beta blockers that are contraindicated or have unacceptable side effects. But in fact, calcium channel blockers (especially diltiazem) are often used in first-line treatment. Because calcium channel blockers have no adverse effects on airway resistance, patients with bronchospasm are more desirable than beta blockers. Patients with peripheral vascular disease and diabetes have better tolerance to calcium channel blockers. In some cases where beta blockers fail to control symptoms, a calcium antagonist can be added cautiously. However, combination therapy will also increase the incidence of adverse reactions (heart failure, hypotension, conduction disorders, etc.), and the results may not be better than the careful treatment of individual drugs. The important clinical differences in various myocardial contractile properties, cardiac conduction and peripheral circulation of various calcium channel blockers can affect the selection of drugs. In view of the fact that the direct negative inotropic effect of nifedipine is often masked by the effects of reflex sympathetic nerves (as may be the case with other dihydropyridines), the electrophysiological effects of these drugs on the sinus and atrioventricular node are extremely mild. Therefore, these calcium antagonists are safer than verapamil for patients who are taking beta blockers and patients with left ventricular dysfunction. Diltiazem is also safer than verapamil in patients with beta blockers. In patients with nifedipine and nicardipine, the symptoms of angina are sometimes exacerbated by reflex tachycardia. Verapamil and diltiazem often cause mild bradycardia, which is beneficial for patients with angina. Verapamil has the strongest effect on atrioventricular node conduction, so calcium antagonists are the drug of choice in cases of supraventricular rapid heart rhythm disorder. Diltiazem may also be beneficial to this.