Necrosis confined to a more or less tissue myocardial ischemia resulting from a sudden coronary artery. During a myocardial infarction, irrigation is no longer; deprived of blood and oxygen, the myocardial cells suffer and die, releasing their cardiac enzymes, with destruction of surrounding tissue. Men are affected twice as often as women. Myocardial infarction is one of the most common causes of death.
Today, the very definition of myocardial infarction tends to disappear in favor of acute coronary syndrome ST more versus acute coronary syndrome not included ST.
The occlusion of one or more coronary arteries is almost always due to the formation of a thrombus (clot) on a plaque consisting of cholesterol deposits against the inner arterial wall. This condition occurs most often in patients with risk factors such as smoking, hypertension, high cholesterol, diabetes, sedentary lifestyle.
In half the cases, infarction occurs after a period shorter or longer during which the subject suffers from angina.
The pain (tightness, burning, sometimes crushing) are felt behind the breastbone (retrosternal), and can radiate to the left arm to the jaw, sometimes in the back. They disappear in a few minutes rest, sometimes with the use of a spray nitro.
In the other half of the cases, stroke is opening, that is to say that there are no warning signs. It manifests itself by severe pain sharp retro sternal (such as angina but longer and more intense). The pain may radiate to the arm, jaw and back. It is often constrictive and accompanied by anxiety and feeling of impending death.
About 20% of patients with myocardial infarction have little or no pain (silent infarction). Often in people with diabetes or the elderly.
Other signs may include:
- Nausea, vomiting
- Pale, grayish, cold sweats
- Death anxiety
- Sudden collapse with loss of consciousness
- Cardiogenic shock
- Pill in women, smoking is associated with prothrombotic
- Sedentary lifestyle
- Coronary personal history or family
- Age> 65 years
- Male but caught by the female menopausal
The diagnosis is made in the presence of the following factors:
ECG qualifying myocardial typical of Pardee wave, Q wave of necrosis (ischemia old), in addition to raising at least 2 bypass the ST segment with sub-pass in the territories opposite (mirror) and loss of asymmetry of the T wave
Typical clinical symptoms but inconstant
Elevation of cardiac enzymes in the blood (enzymes released from myocardial cells, when destroyed):
- CPK MB: Threshold 10ng/ml (nonspecific)
- CTnI, the more specific negative short of 0.4 ng / ml, suspected angina between 0.4 and1 ng / ml, confirmed diagnosis beyond 1ng/ml. However, standards can vary between laboratories and sensitivity tests. Always ask about the standards of your lab
- Myoglobin (nonspecific), as advocated: threshold to 150ng/ml
Note that the threshold of detectability of these markers have a long and kinetic it is unnecessary to achieve within 2 hours after onset of pain.
Note also the need to take blood pressure in both arms to eliminate pain may find its origin in an aortic dissection, and temperature, to eliminate an infectious process such pericarditis, and this before therapy.
Care and treatment:
The No. 1 objective is to minimize the area of ischemia, to limit the loss of myocardial tissue and, ultimately, preserve ejection fraction of left ventricle.
- Emergency hospitalization in an intensive care unit with cardiac angiography table.
- Installation of 2 large peripheral venous channels (14-16G)
- ECG Monitoring 18 leads (devices, precordial, and right posterior), continues.
- Oxygenation systematically according to some authors, or SpO2> 95% according to other
- Antiplatelet therapy varies schools:
- Aspirin 150 to 300mg IVD
- clopidogrel 300 to 600mg depending on the orientation (trhombolyse gesture or angioplasty)
- LMWH, sodium enoxarapine average 100ui/kg
- Or unfractionated heparin in elderly patients (> 75 years) or renal inssufisant
- Use of nitrates and unless hypotension or infringement of the right ventricle
- Support for analgesia (morphine titration)
- Management of anxiety (1 to 2mg/kg hydroxyzine, alprazolam)
- The use of beta-blockers is possible if after the initial charge, the patient remained tachycardic and hypertensive, eg Atenolol 5mg / 5 minutes. However, the use of beta blockers should remain cautious (contraindicated in the COPD, the bronchospastic, AVB II or III, conduction disturbances, impaired ejection fraction …), as may unmask heart failure.
The focus of treatment will then be followed by availability of a table angioplasty.
If angioplasty quickly achievable, a preparation that will be conducted with a antiGpIIbIIIa: abciximab bolus of 0.25 mg / kg and then relay the 0,125 ug / kg / min in SAP (Tentative doses).
If the angioplasty is not feasible, thrombolysis in TNK-tPA (tenecteplase) 1000UI/10kg weight on a dedicated channel (interest VVP 2)
However, thrombolysis is subject to many cons-indications:
- hemorrhage less than a year
- Severe head injury less than three months
- Process active bleeding
- Abnormal hemostasis congenital or acquired
- Recent major surgery (<3 weeks)
- Pregnancy or recent birth (<1 week)
- Arterial dissection
- Severe uncontrolled hypertension
- Maneouvre resuscitation (external cardiac massage in prehospital example)
In addition, the nurse (e) will monitor this thrombolysis: bleeding from the puncture, gingival bleeding, epistaxis, neurological changes (pupillary reactivity, Isocore).
It goes without saying that the patient should remain at rest + + + to minimize oxygen consumption.
- The disappearance of pain
- The normalization of ST segment (low excess delay, disappearance of the mirror effect, resumed the asymmetry of the T wave)
- The appearance of a RIVA, Ventricular Rhythm Accelerated Idio is a rhythm disorder that does not deal with: there is indeed a good indicator of reperfusion. Other arrhythmias can be observed (extrasystoles, salvos of TV …)
- 15% of patients die before reaching hospital, 10% during hospitalization and 10% in the months that follow.
- After 3 to 6 hours, irreversible necrosis of muscle tissue reached settled.
- Necrosis can affect all layers of the heart wall (poor prognosis) or be limited to one part
- The evolution depends lesions. (Reached by 8% of akinetic muscle: reduced compliance, achieving 10% ejection fraction, 23% clinical heart failure)
- heart failure
- heart rhythm disorder
- malfunction of the heart pump
- rupture of the myocardial wall by formation of aneurysm on the scars of scar tissue, or tamponade
- Cardiogenic shock
- Recurrence in 1 / 4 to 1 / 3 cases
Removing risk factors:
- Quitting smoking
- Treatment of hypertension, diabetes and hypercholesterolemia
- Treatment of possible angina
After myocardial infarction, treatment with beta-blockers and aspirin 100mg daily reduces the risk of recurrence.
+ / – Administration of inhibitors of angiotensin converting enzyme and digitalis.