However, as a result of their chemical heterogeneity, each of the calcium blocking agents manifests the noted properties to different degrees. Diltiazem is intermediate in action between nifedipine and verapamil. The major benefit of diltiazem is a reduction in myocardial oxygen consumption. Diltiazem acts as a systemic vasodilator, lowering afterload and reducing ventricular wall tension, as well as contractility. Through its effect on specialized cardiac cells, diltiazem also has minimal effect on heart rate and A-V conduction rate. The above mechanisms work to reduce myocardial oxygen requirement as the primary therapeutic effect of diltiazem. The vasodilatory effect of diltiazem on coronary arteries also enhances delivery of oxygen and favorably affects the balance of oxygen supply and demand. All three classes of antianginal drugs improve oxygen delivery or reduce oxygen consumption to different degrees. However, their net effect is a favorable influence on the balance of myocardial oxygen supply and demand. buy antibiotics online
In summary, the concept of supply and demand attempts to simplify the complex and dynamic process of oxygen delivery and consumption. It underlines the regulators of coronary blood flow and myocardial metabolism. With greater emphasis on the physiologic significance of a coronary lesion, this concept s extension into clinical practice is foreseeable in the near future. Familiarity with these principles will therefore become essential for physicians caring for patients with coronary artery disease.