One day Uncle Chan felt unwell while hiking with friends.
He was experiencing chest tightness and chest pain accompanied by sweating.
Fortunately, one of his companions is a doctor, who instructed him to rest for a while and take a tablet of glyceryl trinitrate, which helped relieve his symptoms in 10 minutes.
Uncle Chan was later diagnosed by a cardiologist with angina pectoris.
Angina is a type of chest pain that is caused by restricted blood supply to the muscles of the heart. Since Chan’s pain was triggered by physical activity, it was referred to as an angina attack.
What should we do when someone is having an angina attack?
A. Take a rest. When someone is having a chest pain, advise them to stop what they are doing and sit down straight away. The patient should feel comfortable and stay calm as much as possible so that the pain could be reduced or even relieved as the muscles of the heart are not subjected to further stress amid the restricted supply of oxygen and blood.
B. Patients who have been diagnosed with angina should always carry with them emergency cardiac drugs like glyceryl trinitrate or isosorbide dinitrate.
When they are having an angina attack, they should put a tablet of glyceryl trinitrate under the tongue, which would then quickly dissolve and start easing the symptoms in two to five minutes. But the effect of the medicine will go away after about 30 minutes. If the pain is not reduced, take another pill after five minutes. Generally, glyceryl trinitrate should be taken three to five times consecutively.
Alternatively, patients could put a 5mg or 10mg tablet of isosorbide dinitrate under the tongue, which should reduce the pain in two to five minutes. Its effectiveness could be up to two or three hours.
Glyceryl trinitrate is another drug that can relieve the symptoms of angina and patients with the condition should have this drug available at all times.
However, patients and their families and friends should take note of the following:
1. Common side-effects of glyceryl trinitrate include headache, dizziness, palpitations, rapid heart beat, low blood pressure and feeling light-headed. Patients should lie down for the time being and oxygen therapy might be applied if necessary.
2. For high-risk individuals who have frequent chest pain, they may have to take the drug before defecation or doing vigorous physical activities. Such a preventive measure could last five to 15 minutes.
3. Patients with glaucoma or intracranial hypertension should not take glyceryl trinitrate as it would increase blood pressure in the eyes and the brain.
4. Glyceryl trinitrate has to be dissolved under the tongue, and each administration should include no more than three tablets. Patients should be sitting down while taking it. The medicine should be kept in the manufacturer’s bottle, and it has to be replaced every six months.
5. Resistance to glyceryl trinitrate is unlikely to develop, given that the dosage is low and taken intermittently. Frequent application might reduce its effectiveness. Taking other angina drugs in between chest pains could restore the body’s sensitivity to glyceryl trinitrate.
6. Medication for angina has to be prescribed by doctor and patients should follow the instructions. For unstable angina, which is a medical emergency, patients should receive medical attention and treatment at once.
This article appeared in the Hong Kong Economic Journal on July 4
Translation by John Chui with additional reporting
[Chinese version 中文版]
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