Further Discussion on Angina Pectoris, July 5, 1987

Further Discussion on Angina Pectoris, July 5, 1987

The pain of angina pectoris is located in the left anterior chest and radiates to the left shoulder and left arm. It occurs after exercise, overeating, or exposure to cold. Occasionally, it occurs at rest. It can be relieved within a few minutes after taking nitroglycerin. Persistent chest tightness without any other explanation is also diagnosed as angina pectoris. The duration of an angina attack should be from a few seconds to 20 minutes. Attacks lasting longer than that may not be angina.

Treatment: The analgesic effect of nitroglycerin has been proven reliable through 200 years of practice. Its mechanism of action is not to dilate coronary arteries, but to reduce cardiac preload (since it dilates both arterial and venous systems, it can also reduce cardiac afterload). Dinitro nitroglycerin, marketed as Isordil, is a medium-effect nitrate; trinitro nitroglycerin is a fast-effect nitrate; tetranitro nitroglycerin (also known as pentyl nitrate), is a long-effect nitroglycerin. During an angina attack, it is advisable to hold nitroglycerin or Isordil under the tongue, with dosages of 0.5 mg and 10 mg respectively. Pentyl nitrate cannot be held under the tongue; it is absorbed in the gastrointestinal tract, 20 mg, taken orally three times daily. Additionally, amyl nitrite is best administered by inhalation, 0.12–0.18 mL per handkerchief, but since this drug can cause severe hypotension or even shock, it is now rarely used. Beta-blocker propranolol usually slows the heart rate and reduces cardiac contractility, which can also relieve angina. When combined with Isordil, the therapeutic effect is doubled because the former can eliminate the latter’s side effects.