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In this video, we are going to talk about angina, and the use of glyceryl trinitrate or GTN as part of the management of that. Angina is a chronic condition. We all develop narrowing of the arteries as we go through life. Male is more at risk than female until the post menopause stage where the risk then becomes equal between male and female.

Angina is the build-up of atherosclerotic plaques inside the blood vessels. What we must remember is, this almost takes you back to your mathematics lessons at school. If you reduce the diameter of a tube, you reduce the amount of fluid that can pass through that tube, not by half but by 16 times. So it's easier to see that in that narrowed artery how much less blood and oxygen and nutrients can get through to the cells beyond. In a normal resting heart, this often does not cause a problem. This is adequate in the early stages of angina. The blood flow is still adequate to supply the myocardium with the oxygen that it needs. But in times of stress or exercise, where the workload of the myocardium increases, not enough oxygen can get beyond the occlusion caused by the plagues. This causes lactic acid to build up inside the cells of the heart and this is what causes the pain.

So as a management regime for angina, and the chest pain associated with angina, we must first look at reducing the workload of the heart. This will involve reassuring our patients, making our patients relaxed and getting them comfortable. We need to carry out an ECG, and if the oxygen saturation are less than 95%, then we need to administer some supplemental oxygen, as well. If the patient's blood pressure is high enough, IE, over 100 millimetres of mercury systolic, then we may administer GTN spray or a tablet to place underneath the tongue.

In the pre-hospital setting, we use a spray which delivers 400 micrograms. We ask the patient to lift up their tongue, give one spray under the tongue and then to close the mouth immediately, and explain that this may well cause a throbbing headache as it's one of the side effects of GTN. What this does is it's distributed around the vascular system and it causes the arteries, the muscles inside the arteries, to relax, therefore reducing the amount of blood returning back to the heart, therefore reducing the workload of the heart, therefore reducing its oxygen requirement. This on its own is enough to alleviate the angina pain, but what we must remember in that if angina on at rest, then it may well be that the chronic condition of angina is now changing to an acute coronary syndrome, which may well lead to a heart attack or a myocardial infarction.