ECG's are a way of picking up abnormalities in cardiac tissue electrial conductivity. The heart uses its own manufactured electrical impulses to contract and operate the heart as a pump. Those electrial impulses must follow certain pathways and gates if the pump is to function properly.
One of the causes of loss or errant activity is tissue death or tissue change, for example scarring or gross enlargement. Chemical imbalances (such as dehydration) cause changes to the electrical activity as well. There are a number of other changes that may be picked up by ECG due to the way they change the conductive pathways in the heart, but if the condition is intermittant, there may be little chance the problem will be picked up on an annual medical. Such intermittant proplems may include palpitations (like when youve drunk way too much coffee or coke and you get that fluttering sensation from your heart and a slight breathlessness with it) and changes in rhythms.
Stenosis of the vessels (or blockages) in the major arteries feeding the heart tissue are usually the result of a number of causal factors. Vascular disease is found to be a result of lifestyle, current or past medical conditions and genetics. Cholesterol is a topic oft referred to as a major culprit. One specific type of cholesterol causing the biggest problem is Low Density Lipid (LDL) as the High density stuff has a number of roles in the bodies chemistry and is used by the body in a munber of ways. Abnormally high levels of anything are not good though. Any imbalances in the way a body deals with chemical balances, blood pressure, infection and so on may contribute to vascular disease. Other culprits are high blood sugar, high sodium (salt) diets, high additive diets (lots of processed foods) and so on.
These chemicals irritate, then start etching the cells away from the vessel walls. The body then treats these areas as it would any other injury. It send clotting factors, white blood cells and so on to repair the area. The result is a swollen part of the blood vessel. As a one off injury, it would repair and no effect would be noted by the vessels owner as body breakdown and repair processes are going on 24/7 in everyones bodies. The continuation of abnormal chemical levels continue to irritate the linings giving no relief. The area also picks up some of the colesterols and deposits the particals as plaques on and under the vessel walls, thus increasing the swelling to the artery. The blood flow no become contricted and like any good venturi, starts interferring with blood flow. Damaged red blood cells cannot carry oxygen as well as a normal cell.
An inflammed, plague laden artery cannot expand and contract like its healthy counterparts, so when placed under stress, pressure continues to errode and scar the lining of the vessel, impedes the flow of blood to the heart muscle, and thus anything down stream of the blockage suffers for lack of oxygen and nutrients initially, then, as the oxygenless environment continues, the acid waste as a result of cells operating without oxygen builds up and is not removed, thus further irritating the surrounding muscle tissue. If the process is allowed to continue, the heart muscle dies, and bit by bit, the pump is rendered useless. If no blood is pumped to the lungs for oxygenation, the body shuts down.
Seeming fit and healthy folks dying as a result of blockages within heart arteries are unnervingly common enough, some resulting from a clot that may have lodged in a narrowed artery, or a burst anuerism (weakened wall in the blood vessel causing a balloon and eventually a blowout something like a tyre inner tube), or gradual blocking of the artery. Some symptoms are usually evident prior to the heart attack such as a feeling of tightness or breathlessness upto a number of days prior. The pain is usually either exercise or stress induced. The clot related ones are usually very sudden. The pain may well not be recognised as being cardiac related as if youve never had heart related pain, youve not much to compare it to....
A close family friend aged 42, (read fitness fanatic!) was suffering a non specific type chest pain for 3 days before his ambo wife finally got him to tell her his symptoms and she rushed rushed him to hospital. He had a double bypass a couple of weeks later. He had put his pain down to a "flu".
His steady western diet mixed with genetics, factor in being a male, slightly above average blood pressure, and he was a recipe for risk. He was one of the lucky ones but now has to be on medication for the remainder of his life to stop clots, as the part of his heart muscle that died will now scar and not operate properly. That will now show up on any ECG...
The best advice to give is, if you or a friend develops breathlessness, a kind of washed out appearance, and aching within the chest cavity, then cease exercise. The pain does not usually change either on breathing in or out but remains fairly constant. The pain can appear to be in the left jaw, around the stomach area or the left arm. Ive had patients say they had nothing more than a back ache! It may go away after a few minutes rest, only to return unpon commencement of activity. If you do develop some of these symptoms or develop a sudden gripping pain, call an ambulance.. fast. Dont get someone to drive you as treament is commenced by the paramedic crew. The earlier intervention is achieved, the better the outcome for the heart tissue and thus the patient.
As a bystander, keep things simple, sit the patient down but dont lie them down unless unconscious (then they go in the "recovery position". Its far easier to breath while sitting upright. Loosen contrictive clothing. Get any details of allergies and current medications and keep an eye on the person for any changes in their condition.