by Amelia Walker

Created on: June 21, 2010

A 55 year old woman had been complaining of chest pains on physical exertion relieved by rest. She was diagnosed to be suffering from ischemic heart disease. Part of her treatment included taking aspirin tablets daily. She noticed gastric pain on and off after starting aspirin but thought nothing of it. One day she suddenly vomited huge amounts of blood. On examination she appeared pale, heart rate was 100 beats per min and BP was 90 / 60 mm Hg lying down. On standing up, her heart rate was 140 beats per min and 75/50 mm Hg. Her hematocrit was 30% (normal = 35-45%). A gastroscopy was performed which showed a bleeding ulcer.

 How physical exertion caused chest pains in the patient.

 Exercise leads to increased oxygen demand from muscles. This leads to the body responding by causing sympathetic stimulation with the concomitant suppression of the parasympathetic system. This caused the contractility and heart rate to go up, so that the muscles could receive enough oxygen. However, an increase in contractility and rate of contraction increases the oxygen demand of the heart. At the same time, diastolic time is more reduced than systolic time during an increase in heart rate. Because the cardiac muscle is perfused by the coronary arteries, and blood flow in the cardiac arteries is the greatest during diastole, reducing the time for diastole reduces the blood flow to the myocardium. These two factors of increasing oxygen demand and lower coronary artery perfusion time leads to lower perfusion pressure, and insufficient oxygen demand to meet the metabolic demand. The heart then undergoes ischemia, which is a shortage of oxygen. This ischemia causes the local release of chemicals like prostaglandins or bradykinins in order to cause coronary artery dilation. This also causes triggering of the pain receptors, which causes chest to feel painful.

Why was aspirin prescribed?

Aspirin inhibits cyclooxygenase as well as prevents the adhesion of platelets. Cyclooxygenase catalyzes the formation of prostaglandins as well. This stops the pain. It also has an effect on platelet adhesion. If the patient is suffering from coronary heart disease due to the deposition of cholesterol and the narrowing of coronary blood vessels. Aspirin prevents the formation of a platelet plug which would cause further restriction of blood flow. Thus, it helps to prevent cardiac ischemia by ensuring that blood clotting does not occur such that oxygen is adequately delivered to the tissues

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