Chapter 46: Antianginal Agents

Antianginal Agents focuses on Antianginal Agents used in nursing pharmacology to manage cardiovascular conditions, primarily Coronary Artery Disease (CAD), which is characterized by the progressive narrowing of coronary arteries due to atherosclerosis—the buildup of fatty plaques, or atheromas, leading to loss of elasticity and responsiveness in the vessels. This narrowing disrupts the critical supply-and-demand ratio of oxygen in the heart muscle, a balance normally maintained because the myocardium receives blood supply during diastole. The resulting lack of oxygen manifests as chest pain, known as angina pectoris. The three types of angina covered are stable angina (pain relieved by rest), unstable angina (ischemia occurring unpredictably or at rest), and Prinzmetal angina (caused by coronary artery vasospasm). When occlusion is complete, it results in a myocardial infarction (MI), leading to tissue necrosis and permanent scar tissue formation. Antianginal therapy aims to restore balance either by increasing oxygen supply via vessel dilation or by decreasing myocardial oxygen demand by reducing heart rate, preload (venous return), afterload (arterial resistance), or contractility. The pharmacological agents utilized include Nitrates (e.g., nitroglycerin), which cause direct smooth muscle relaxation, profound vasodilation, and a subsequent decrease in preload and afterload, making them effective for treating acute angina attacks. Beta-adrenergic blockers (e.g., metoprolol) are used for long-term management of stable angina by blocking sympathetic influence, thereby decreasing heart excitability and workload, though they are contraindicated for Prinzmetal angina. Calcium channel blockers (CCBs) (e.g., diltiazem, amlodipine) inhibit calcium movement into muscle cells, leading to vasodilation, decreased workload, and effectiveness in relieving the vasospasm associated with Prinzmetal angina. Finally, the newer class, the piperazine acetamide agent ranolazine, is used for chronic angina and decreases myocardial workload through an unknown mechanism without decreasing heart rate or blood pressure, but it does prolong the QT interval. Nursing considerations emphasize careful assessment for contraindications (like severe hypotension or head trauma), monitoring for adverse effects such as reflex tachycardia and severe hypotension, providing patient education on proper administration techniques (especially for sublingual and transdermal nitroglycerin), and advising patients on lifestyle modifications to decrease CAD risk.