Myocardial infarction (MI is a common abbreviation) is a necrosis (cell death) of a portion of the heart muscle that is fed through a vessel obliterated by a thrombus (blood clot). In common parlance, it is most often called a heart attack. It occurs when one or more coronary arteries become blocked. The heart muscle cells (muscle forming the heart) irrigated by this (or these) artery(ies) are then more oxygenated, which causes their suffering and may lead to their death. Area « infarct » won’t shrink properly.
The number of myocardial infarction decreases significantly (nearly 60% in 25 years), probably due to the improvement of the management factors for cardiovascular risk. It affects about 100,000 to 105,000 people per year in United Kingdom, and 2 ½ million in the United States. Myocardial infarction reached more often men than women and usually before the age of 60. Myocardial infarctions are eight times more common in patients with sleep apnea syndrome, detected by snoring and daytime sleepiness, especially if there is associated hypertension. Studies also indicate a relationship with the importance of the work of breathing, which can be easily reduced with RespiFacile nasal dilator.
Necrosis of cells composing the myocardium (death) resulting from an absence of oxygen results in the release of enzymes in the blood which in turn destroy nearby tissue of the lesion.
Key risk factors now recognized are:
- Tobacco (or passive smoking)
- Excess cholesterol
- Sex (male)
- Heredity (infarction in the family)
The symptom is chest pain. It relates to the retro-sternal region (behind the breastbone). It is violent, usually intense, and long and not (or little) trinitrate-sensitive (trinitrate relieves the pain of angina pectoris). It is called pan-radiant, radiating to the back, the jaw, the shoulders, the arms, the left hand, the upper abdomen (stomach). It is agonizing, oppressive (breathing difficulty).
This description corresponds to the typical form and characterized. In practice, many variations exist until myocardial asymptomatic (no pain, no breathing problem, no anxiety or without discomfort), Myocardial infarction was discovered during an electrocardiogram « systematic », for example during a checkup.
On the symptomatic level, there are misleading forms, with limited pain to one (or severalà irradiation(s), special forms, digestive with epigastric pain (stomach area) and abdominal pain, forms where predominate a particular event (eg vagal, with sweats, malaise, feeling of warmth, belching), limited forms with an agonizing oppression, forms dominated by a complication, discomfort, sudden death, pulmonary edema (acute unexplained shortness of breath), cardiogenic shock (pulse voltage and breathtaking), tamponade (compression of the heart by an effusion), arrhythmias (palpitations, malaise), psychiatric forms (sudden disorientation), isolated fever.
Before any event which we do not have the certainty of the diagnosis and / or in people whose risk factors are predominant, perform an electrocardiogram is used to confirm or refute the diagnosis of myocardial infarction.
It is a medical emergency. The hospitalization must be made in specialized units with equipment for reanimation and continuously monitoring of vital parameters (electrocardiogram).
The patient is in complete rest, possibly in oxygen with an IV infusion. A scope of electrocardiographic monitoring is implemented. Antiplatelet therapy (clopidogrel and aspirin) is implemented, in addition with anticoagulants (heparin). The relief of pain may require the use of opioids. The use of nitrates infusion is common.
Attitude towards the coronary arteries mainly depends on the type of infarction, with or without Q-wave on the electrocardiogram.
Besides managing the pain and possible complications, the crucial issue is to unblock as soon as possible (preferably in the first four hours) the coronary arteries concerned. The more early the unblocking of coronary artery is, the less sequelae there will be. Any suspected myocardial infarction (in practice prolonged chest pain) should lead to the call of medical regulation for taking the fastest possible load.
Two methods are used to unclog an artery:
*By « medical » treatment, using products that are designed to destroy (« lyse ») thrombus (blood clot) occluding the artery : it is the « thrombolysis / fibrinolysis » (injection intravenously – as in a blood collection-. This thrombolysis may be done on the site of care of heart attack, that is to say before arrival in hospital (pre-hospital thrombolysis). The fibrinolytic products the most used are the different forms of TPA (tissue plasminogen activator).
* By « instrumental » unblocking angioplasty, introducing, during coronary angiography (X-ray of the coronary arteries) a micro catheter into the artery to dilate the responsible lesion. The gesture is most often associated with the introduction of a stent (spring) in the artery. The practice of angioplasty however requires hospitalization in a specialized center. The success rate of the gesture is greater than that of fibrinolysis.
The choice between these two methods depends mainly on their availability (nearness a center practicing angioplasty). They are complementary, an emergency angioplasty can be offered in the event of failure of fibrinolysis (judged on the persistence of pain and abnormalities on the electrocardiogram), thus allowing a better chance of favorable outcome. By cons, the systematic use of angioplasty in an emergency, whatever the result of fibrinolysis, has not shown interest.
Mortality is mainly due to heart failure, resulting to the infarct size or, more rarely, to complications such as stroke.