Pharmacologic management of myocardial ischemia.
Pharmacologic intervention is critical to the management of myocardial ischemia. Four classes of drugs are now used in therapeutic regimens for ischemia. beta-Adrenergic blockers decrease ischemia by blocking beta 1-mediated inotropic and chronotropic effects, thereby decreasing myocardial oxygen consumption. Calcium channel blockers alter fast- and slow-response action potentials by decreasing transmembrane calcium flux, resulting in decreased conduction velocity and heart rate and prolonged effective refractory period. These effects positively influence ischemia and atrial dysrhythmias. Additionally, these agents decrease excitation-contraction coupling in vascular smooth muscle, resulting in coronary and peripheral vasodilation. Organic nitrates and nitrites decrease vascular smooth muscle contraction and preload, and afterload, precipitating a decrease in myocardial oxygen consumption and ischemia. They also improve blood flow to areas of compromised flow. Thrombolytic agents are administered in acute situations to dissolve the occluding thrombus, but they must be used within a few hours of the injury. These drugs activate the conversion of plasminogen to plasmin, which breaks down the clot into fibrin degradation products. The choice of agents is determined by the etiology of the patient's ischemia, his or her response to the drug, and the presence of concomitant disease processes.
Dix-Sheldon
D K
DK
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D003327:Coronary Disease / Q000188:drug therapy* / Q000451:nursing / Q000503:physiopathology; D005343:Fibrinolytic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D014665:Vasodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use
D000319:Adrenergic beta-Antagonists; D005343:Fibrinolytic Agents; D014665:Vasodilator Agents